review article nanobiosensors: concepts and variations · 2019. 7. 31. · nanobiosensors: concepts...

Hindawi Publishing CorporationISRN NanomaterialsVolume 2013 Article ID 327435 9 pageshttpdxdoiorg1011552013327435

Review ArticleNanobiosensors Concepts and Variations

Parth Malik1 Varun Katyal2 Vibhuti Malik3 Archana Asatkar4

Gajendra Inwati1 and Tapan K Mukherjee5

1 Center for Nano Sciences Central University of Gujarat Gandhinagar India2Department of Chemical Technology Delhi Technological University Delhi India3 Department of Phramaceutics Hindu College of Pharmacy Sonepat Haryana India4 School of Chemical Sciences Central University of Gujarat Gandhinagar India5 Indian Institute of Science Education and Research Mohali Chandigarh India

Correspondence should be addressed to Tapan K Mukherjee tapanmuyahoocom

Received 11 June 2013 Accepted 21 August 2013

Academic Editors K C Hwang and D Pissuwan

Copyright copy 2013 Parth Malik et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Biosensing has been one of the hottest topic attracting scientific minds since long back It is so as biological entities are verycomplex and are directly associated with the existence of a healthy environment The design of biosensors also has witnessedsignificant changes in the recent past Biosensors for applications as diverse as food quality estimation environmental monitoringand diagnosis of clinical and metabolic complications have come to the fore Nanotechnology has bestowed some highly excitingingredients for the improvement of sensing phenomenonThe use of diverse nanomaterials ranging from nanoparticles nanotubesnanorods and nanowires has enabled faster detection and its reproducibility in a much better way The unique properties ofnanomaterials such as high electrical conductivity better shock bearing ability and the sensitive responses such as piezoelectric andversatile color based detection mechanisms are only the results of congregation of nanomaterial properties This paper highlightsthe different types of biosensors based on different types of nanomaterials and their developmental and implicational aspects

1 Introduction

Sensing the biological responses has assumed great signif-icance in the current scenario of ever dynamic environ-mental developments and corresponding altered homeostatichappenings occurring at both in vivo as well as ex vivolevelsThe analysis of behavior of the ever changingmaterialshas assumed great significance in areas like pharmaceuticaldiagnosis screening food quality and environmental appli-cations In this reference the development of efficient biosen-sors which can analyze the minutest details of the biologicalinteractions even at a very small scale and with extremeprecision and maximum ever possible sensitivities deservesurgent attention [1] A key component of the biosensingis the transduction mechanisms which are responsible forconverting the responses of bioanalyte interactions in anidentifiable and reproducible manner using the conversion ofspecific biochemical reaction energy into an electrical form

through the use of transduction mechanisms Nanomaterialscan be wonderful incumbents in this dimension as they havehigh surface area to volume ratios which allow the surface tobe used in a better and far more diversely functional mannerMoreover their electromechanical properties are the won-derful assets for the biosensor technology Nanostructuralwonders provided by nanotechnology have revolutionizedthe happenings in the domain of molecular biology whichhave provided an opportunity for manipulation of atomsand molecules and monitored the biological phenomenonat the physiological level with far greater precision Theterminology nanobiosensors a misnomer in the sense that ithas the word nano prefixed to it To get to the real technologyone must soundly gather the idea of what a biosensor is Asnanoscience is interdisciplinary in nature so putting the wordnano as prefix often implies the use or manipulation at a scaleequivalent to one-billionth of a meter

2 ISRN Nanomaterials

analyzes)

Biosensor components (in order)

Bioreceptor(material which

Transducer(signal

conversion)

Detector (reproducible

response)

Figure 1 Depiction of the block diagram of a biosensor

2 Definition and Conceptual Idea

A biosensor can be defined as a sensing device or a measure-ment system designed specifically for estimation of a mate-rial by using the biological interactions and then assessingthese interactions into a readable form with the help of atransduction and electromechanical interpretation Figure 1gives us information about the three main components of abiosensor In terms of the conceptual and fundamental modeof operation these components are namely bioreceptortransducer and the detector The main function or purposeof a biosensor is to sense a biologically specific materialOften these materials are antibodies proteins enzymesimmunological molecules and so on

It is done by using another biologically sensitive materialthat takes part in the making of bioreceptor So a bioreceptoris that component of a biosensor which serves as a templatefor the material to be detectedThere can be several materialswhich can be used as bioreceptors For instance an antibodyis screened using antigen and vice versa a protein is screenedusing its corresponding selective substrate and so on Thesecond component is the transducer system The main func-tion of this device is to convert the interaction of bioanalyteand its corresponding bioreceptor into an electrical formThe name itself defines the word as trans means change andducer means energy So transducer basically converts oneform of energy into another The first form is biochemical innature as it is generated by the specific interaction betweenthe bioanalyte and bioreceptor while the second form isusually electrical in nature This conversion of biochemicalresponse into electrical signal is achieved through transducerThe third component is the detector system This receivesthe electrical signal from the transducer component andamplifies it suitably so that the corresponding response can beread and studied properly In addition to these componentsa very essential requirement of the nanobiosensors is theavailability of immobilization schemes which can be used toimmobilize the bioreceptor so as to make its reaction withbioanalyte much more feasible and efficient Immobilizationmakes the overall process of biological sensing cheaper andthe performance of the systems based on this technology isalso affected by changes in temperature pH interference bycontaminants and other physicochemical variations [2]

3 Nanobiosensors The Merging ofNanotechnology with Biosensors

The understanding of biosensing concept lays the foun-dation for studying and developing the nanobiosensorsNanobiosensors are basically the sensors which are madeup of nanomaterials and interestingly these are not thespecialized sensors which can detect the nanoscale eventsand happenings The question that sustains interest from theabove description is that why nanomaterials are intended tobe used in making biosensors or whether they are going todrive in any significant difference in the overall technologyNanomaterials are a unique gift of nanotechnology to themankind these are the materials which have one of theirdimensions between 1 and 100 nanometers The size con-straints of these materials makes them very special as theyhave most of their constituent atoms located at or near theirsurface and have all vital physicochemical properties highlydifferent from the same materials at the bulk scale Theycan play very efficient roles in the sensing mechanism of thebiosensor technology Integrated devices of the nanomateri-als with electrical systems give rise to nanoelectromechanicalsystems (NEMS) which are very active in their electricaltransduction mechanisms Several nanomaterials have beenexplored on the basis of their electronic and mechanicalproperties for their use in improved biological signaling andtransduction mechanisms Some of such materials that arewidely employed include nanotubes nanowires nanorodsnanoparticles and thin films made up of nanocrystallinematter [3] Amongst these the use of nanoparticles is beststudied and analyzed till date Nanobiosensors have servedas very potent developmental inroads in the biosensor tech-nology which has been possible only due to the wondersof nanotechnological implications of the matter A widevariety of biosensing devices that employ nanoparticles ornanostructures have been investigated in a number of studiesthroughout the world These can be as diverse as usingamperometric devices for enzymatic detection of glucose tousing quantum dots as fluorescence agents for the detectionof binding and even using bioconjugated nanomaterialsfor specific biomolecular detection These include colloidalnanoparticles which can be used to conjugate with antibodiesfor immunosensing and immunolabelling applicationsThesematerials can also be used to enhance the electron micro-scopic detections Furthermetal based nanoparticles are veryexcellent materials for electronic and optical applications andcan be efficiently used for detection of nucleic acid sequencesthrough the exploitation of their optoelectronic properties

Table 1 shows the main types of nanomaterials beingemployed for further improvising upon the sensing mecha-nisms that are conventionally being employed in the biosen-sor technology It highlights the potential advantages of sev-eral nanomaterials employed and some evidence witnessedtheir use so far (encoded by corresponding references)The details of different biosensors developed by the use ofdifferent materials at the nanoscale are mentioned further inthe text Even magnetic nanoparticles made up of iron andits oxides have been used for specific and efficient detectionof magnetism based events and interactions like those of

ISRN Nanomaterials 3

Table 1 Depiction the overview of nanomaterials used for improv-ing biosensor technology

Sr no Nanomaterialused Key benefits References

(1)Carbon

nanotubes

Improved enzyme loadinghigher aspect ratios abilityto be functionalized andbetter electricalcommunication

[4ndash6]

(2) nanoparticles

Aid in immobilizationenable better loading ofbioanalyte and also possessgood catalytic properties

[7ndash10]

(3)Quantum

dots

Excellent fluorescencequantum confinement ofcharge carriers and sizetunable band energy

[11ndash13]

(4) Nanowires

Highly versatile goodelectrical and sensingproperties for bio- andchemical sensing chargeconduction is better

[14ndash16]

(5) Nanorods

Good plasmonic materialswhich can couple sensingphenomenon well and sizetunable energy regulationcan be coupled withMEMS and induce specificfield responses

[17ndash19]

magnetic resonance imaging (MRI) These particles can becoupled with fluorescent molecules or can be made to deliverspecific responses by coupling with externally applied mag-netic fields Similarly zinc and zinc oxide based nanostruc-tures have been extensively used for sensing of biochemicalphenomenon in a much more precise and sensitive mannerThese have been used in optimized detection of cholesteroland many other metabolic intermediates Continuing alongthe same direction carbon nanotubes have also been used tooptimize the biosensing events with reference to their abilityto allow for rapid detection and much better interactionsbetween the analyte and the bioreceptor molecule Carbonnanotube based biosensors have been actively in use for thedetection of glucose [20] and insulin [21] The text aheadmentions the advantages and outcomes of the use of differentnanomaterials and their inherent benefits and the criticalparameters in which they can have significant impacts andyield significantly better results

4 Selection and Optimization ofNanomaterials for Sensor Technology

There is a multitude factors which govern or decide theuse of a particular kind of nanomaterials for biosensingapplications These factors are the chief ingredients of theirphysical and chemical properties alongwith their energy sen-sitive and selective responses Table 1 has already mentioned

the main important nanomaterials employed for biosens-ing applications Before exactly implementing or adding ananomaterial for the sensing applications we first focuson their desired manufacturing which is a part of experi-mental design known as ldquoNanofabricationrdquo The techniqueof nanofabrication targets two vital operations namely themanufacturing and design of nanoscale adhesive surfaces viathe technology of integrated circuits and the engineering ofnanomaterial surfaces through the process of micromachin-ing This technique thus developed for biosensing uses thevariations of four basic processes namely photolithographythin film etchinggrowth surface etching strategies andchemical bonding parameters

Nanoscale electrodes which have come into pictureas a result of lithography technique have enhanced thebiosensing accuracy by providing much better and greatersurface areas that in turn enable the immobilization to beachieved with greater precision [22] Glucose biosensorsmaking use of enzyme glucose oxidase have been developedusing these innovations The strategies involving the use ofactive nanoparticles of platinum over the sheets of carbonnanotubes have significantly enhanced the immobilizationof enzyme systems required for the detection of the analytematerialsThese systems have significantlymuchwider appli-cations to biosensing technology enabling the detection ofglucose from several sources other than blood In a similarmanner couples of immunosensors have also been developedwhich involve coating of thin films over the sensing surfacethat enables faster and better detection of the correspondinganalytes [23]

Highly sensitive electrical and electromechanical prop-erties are incorporated into several materials by engineer-ing them with nanoelectromechanical systems (NEMS)which have enabled the generation of complex electricalmechanical fluidic thermal opticalandmagnetic propertiesof the materials with sizes down to the nanometer levelNEMS technology has thus provided many materials withnovel properties due to their nanoscale functionalizationNEMS and MEMS devices have enabled better and bettersophisticated performance of the mechanical materials as themechanical properties of a material are a critical functionof its size In addition these devices have been coupledwith biological systems and molecules to improve their bioadhesion characteristics and the response to a wide rangeof stimuli With the implementation of NEMS and MEMSsurface forces like friction adhesion cohesive forces andviscous drag forces can be controlled in a very precisemannerthat enables the bestmodeling of the biochemical interactionstaking part in the biosensing technology [24]

Another important factor considered while using nano-materials for sensing application is the monitoring andoptimization of their optical properties The phenomena likesurface plasmon resonance are very interesting and in partic-ular expected from nanoparticles so as tomaximize the sharpand precise scale optical response of the sensing materialswith the incident light The surface plasmon resonance effectis concerned with the excitation of particle surface with theionic species and charged particles which create ions andresult in excitation of the fluidic state of charged particles


This property is highly suitable in case of nanoparticles dueto their unique optical properties which give them photoniccharacter and excellent ability to be used as fluorophoresThisphenomenon makes use of total internal reflection whichtakes place for angle of incidence reaching beyond a criticalvalue Here the reflection of light through a thin film ofmetallic nanoparticles coated over a surface is optimizedby the corresponding adjustment of the critical angle ofreflection In case of nanomaterials this phenomenon ishighly logical and is especially named as localized surfaceplasmon resonance [25] Surface plasmon resonance effect isalso dependent upon the refractive index of a medium and itis the most fundamental property governing the flow of lightthrough a medium Due to the phenomenon of surface plas-mon resonance a nanobiosensor is better equipped to detectthe minutest interacting phenomenon which enables a fargreater and much reliable degree of estimation of biologicalinteractions through a nanobiosensor in comparison with abiosensor [26ndash28]

In this way nanomaterials irrespective of their natureneed to be optimized for their performance and effect asper the desired goal before being actually implementedfor the biosensing purpose Nanostructured semiconductorcrystals can be efficiently used to improve the detectionof neurological responses via coupling through the sensingmolecule of biological nature These can be coupled withpeptide assembly of a range of nanomaterials so that efficientinteraction can be generated by means of self-assembly andthis also saves a lot of time that is being involved in thecurrently available technologies and methods Moreoverthese can rapidly detect the biological stimulus such as thatof a DNA segment or a characteristic nucleotide sequencepertaining to proteins or even RNA [29] Moreover a keystrategy into shaping-up of nanomaterials for desired applica-tions involves the tuning and engineering of their surface bysophisticated inroads collectively termed as micromachiningprocedures Factors like aspect ratios functionalization withother materials and compatibility issues with respect to thematerial being analyzed for are highly critical for the use ofnanomaterials in biosensing applications

5 Nanobiosensors Variations and Types

The classification of nanobiosensors is a very diverse areaThis is so as it is based on the nature of nanomaterialsincorporated in the biosensing operation Moreover theclassification here is not as simple as it is in the case ofbiosensors In case of biosensors we classify the sensors ontwo criteria namely the type of material to be analyzedand the other one is on the basis of signal transductionmechanism employed For instance if we are screeningany antigen or enzyme through the biosensors we namethem as antigen biosensors or enzyme biosensors as perthe convention of naming a biosensor through the natureof the analyte Similarly if we arrive at the classificationof biosensors with respect to their sensing mechanism themain types are electrochemical calorimetric optical andacoustic Each of these classes is based on the transduction

mechanism involved and includes a series of overlappingsensor categories under it For instance amperometric andpotentiometric biosensors come under the category of elec-trochemical sensors likewise optical biosensors carry opticalfiber based sensors and surface plasmon resonance basedsensors under them [30]

Considering the classification of nanobiosensors weobserve that the criteria for classification are the natureof nanomaterials being involved for improving the sensingmechanism For instance nanoparticle based biosensorsinclude all the sensors which employ metallic nanoparticlesas the enhancers of the sensing biochemical signals Sim-ilarly nanobiosensors are called nanotube based sensors ifthey involve carbon nanotubes as enhancers of the reactionspecificity and efficiency while biosensors using nanowiresas charge transport and carriers are termed as nanowirebiosensors Likewise there are quantum dots based sensorswhich employ quantum dots as the contrast agents forimproving optical responses The text ahead enlists some ofthe major classes of nanobiosensors developed till date andthose which are in practical use

51 Nanoparticle Based Sensors

511 Acoustic Wave Biosensors Acoustic wave biosensorshave been developed to amplify the sensing responses so as toimprove the overall preciseness of the limits of biodetectionThere can be so many stimulus based effects in these kindsof sensors The mass based variant of these sensors involvesthe conjugation of antibody modified sol particles whichbind themselves on the electrode surface that has beencomplexed with the particles of analyte conjugated in amanner that antibody molecules are immobilized over theelectrode surfaceThe large mass of bound sol particles of theantibody results in a change in the vibrational frequency ofthe quartz based sensing platform and this change acts as thebasis of detection In general the preferred diameter of the solbased antibody particles is between 5 and 100 nm Particles ofgold platinum cadmium sulphide and titanium dioxide aregenerally preferred [31 32]

512 Magnetic Biosensors Magnetic biosensors utilize thespecially designed magnetic nanoparticles These are mostlyferrite based materials either used individually or in com-bined form These types of sensors are very useful withreference to the biomedical applicationsThemagnetic mate-rials enable a great deal of diversity for several analyticalapplications This is so because the magnetic compoundsinvolved in screening constituted of iron coupled with othertransition metals which have different properties With theincorporation of magnetic nanoparticles the conventionallyused biodetection devices have further become more sensi-tive and powerful Alloys of transition metals with iron andother materials having unpaired electrons in their d-orbitalshave been highly versatile in their magnetic behaviors Avery popular kind of materials that have come to the foreinvolving these employs magnetic bioassay techniques thatare used for specific isolation of magnetically labeled targets


with the help of a magnetometer [33] Special devices suchas superconducting quantum interference devices (SQUID)have been used for rapid detection of biological targets usingthe super paramagnetic nature of magnetic nanoparticlesThese devices are used to screen the specific antigens fromthemixtures by using antibodies bound tomagnetic nanopar-ticles [34] These make use of super paramagnetic effectof magnetic materials which is particularly observed in thenanoscale particles

513 Electrochemical Biosensors These sensors basicallywork to facilitate or analyze the biochemical reactions withthe help of improved electrical means These devices aremostly based on metallic nanoparticles The chemical reac-tions between the biomolecules can be easily and efficientlycarried out with the help of metallic nanoparticles whichsignificantly help in achieving immobilization of one of thereactants This ability makes these reactions very specificand eliminates any possibility of getting undesirable sideproducts In this reference colloidal gold based nanoparticleshave been used to enhance the immobilization of DNAon gold electrodes which has significantly increased theefficiency of an overall biosensor by further lowering thedetection limit [35] Biosensors have been designed usingenzyme conjugated gold nanoparticles for the identificationof glucose xanthine and hydrogen peroxide [36ndash38] In asignificant study by Xu et al the analysis of electrochemistryof enzyme systems comprising of horse reddish peroxidaseimmobilized on gold electrodes loaded with nanoparticlesof carbon has been put forward [38] The study predicteda faster amperometric response and faster and much betterelectrocatalytic reduction ability for horse reddish peroxi-dase As a result the biosensor developed showed improvedsensitivity andmuch lower detection limit as compared to theone without using nanoparticles

In a similar trend nanosized semiconductor crystalscan be used to improve the efficiency of photochemicalreactions and can be tagged to biological entities like thoseof enzymes and precursors to design novel photo electro-chemical systems In this dimension Curri et al (2002) haveused immobilized nanocrystalline CdS using self-assemblyapproach so as to prepare an enzymatic detection systembased on immobilized formaldehyde dehydrogenase onto thegold electrodes in order to carry out the catalytic oxidationof formaldehyde [39] In several other studies metal basednanoparticles have been used for coupling themselves withbiological probes and then carry out useful detection of thespecificmolecules from amixture Bioassays based on biotin-streptavidin specificity have been designed in this regard [40]

52 Nanotube Based Sensors Carbon nanotubes are one ofthe most popular nanomaterials known right now in theworld of material science and optoelectronic applicationsSince their discovery in 1990rsquos they have attracted interestworldwide because of their extraordinary properties themost vital of which are the electronic conductivity flexiblephysical geometric features and the ever dynamic physi-comechanical properties ranging from high aspect ratios to

very good functionalization abilities along with having highmechanical strength and folding abilities Because of theseattributes both single walled nanotubes as well as multi-walled nanotubes have been used in designing biosensors forbetter and better performances [41 42]

The most popular sensing advances that have come tothe fore are the developments in the design of glucosebiosensors that involve the use of nanotubes as immobi-lizing surfaces for enzyme glucose oxidaze this enzymeis used for estimation of glucose from the several bodyfluids In convention the sensors using enzymes predictedthe presence of glucose from major body tissues but theuse of nanotubes as assemblies for immobilization has ledto the estimation of glucose from even scarce body fluidssuch as tears and even saliva In one such arrangementsingle walled nanotubes have been wonderfully employed forenzymatic detection of glucose and this innovation has alsoyielded significant increase in the enzyme activity [43] Theenhanced performance of the biosensor was analyzed andfound so largely due to the high enzyme loading and betterelectrical conductivities of the nanotubes Not only withtheir structural flexibilities carbon nanotubes have also beenused for enhancing the electrical detection of the sensingphenomenon owing to their better and smoother electrontransfer flow characteristicsThe significant improvements inthe catalytic biosensors have been widely exploited in severalstudies and in one such study this innovation resulted inbetter oxidoreductase performance in both glucose oxidaseand flavin adenine dinucleotide precursors binding to theirsubstrates more efficiently and in a much more controllablemanner [44] Likewise chemoelectroluminiscence effect hasbeen improved by coupling CNTs to the sensing moleculesof a sensor through better conductance of charge carriersand controlling their required flow characteristics In asignificant and comprehensive review biosensors based oncarbon nanotubes have been extensively summarized for keybreakthroughs and advantages that they get bestowed withby the incorporation of nanostructured arrays of carbonnanotubes and the related structure sensitive assembliesThisreview highlights the functionalization potential of carbonnanotubes and their rapid friendliness for being coupled withbiomolecules likeDNA proteins oligonucleotide probes andtheir corresponding benefits in an excellent manner [45]

53 Nanowire Based Sensors Nanowires are cylindricalarrangements just like those of carbon nanotubes havinglengths in the order of few micrometers to centimeters anddiameters within the nanorange Nanowires are the one-dimensional nanostructures with very good electron trans-port properties Significantly the motion of charge carriersin the nanowires is vigorously improved and different fromthose in bulk materials Sensors based on nanowires arevery less in number but literature reports some excitingexamples where use of nanowires has significantly improvedthe performance and detection of biological materials Inone such study Cui and Lieber group have reported theperformance of biosensors based on silicon nanowires dopedwith boron and used them for the detection of biological


and chemical species [46] Semiconductor nanowires havebeen exploited in a great detail and have also been usedfor coupling a number of biomolecules for identifying theirspecifically linked substrates In a study silicon nanowirescoated with biotin have been used for the detection andisolation of streptavidin molecules from a mixtureThe smallsize and capability of these nanowires make them idealcandidates to be used for biodetection of pathogens andmany other real time analysis of a wide range of biologicaland chemical species thus vastly improvising the currentaccuracies of presently used in vivo diagnostic proceduresAs these sensing materials work on very precisely defineddimensions they can also be used to accomplish in vivoapplications and operate in the smallest environments withinthe living cells In one such study Wang et al have usedoptical fibers with diameters in the nanosize and coated withantibodies to detect the presence of toxicantswithin the singlecells [47] In another very closely related study Cullum et alhave reported the synthesis of ZnO nanowires coated themover the gold electrodes and then used them for detectionof hydrazine using amperometric responses [48] They haveproposed a high sensitivity low detection limit and farlower response times response times than those reportedin the conventionally used reported in the conventionallyused sensor systems Nanowires are very versatile in theirperformance and are significantly better than nanotubes intwo major ways First they allow a range of modificationsin their design by control of operational parameters duringtheir synthesis Secondly they possess a lot muchmore scopefor the development of functionalized assemblies by virtueof the existence of compatible materials on their surfacesDespite very well-known synthesis procedure for nanowiresynthesis their use in the development of sensing devices hasmet several challenges [49] It has been reported by severalrelated studies that it is difficult to incorporate nanowiresinto the sensing systems for the overall improvement in theirelectrical conductivities to be realized In a very advancedstudy Lieber group have rigorously worked on semiconduc-tor nanowires and synthesized thembyusing combinations ofpreviously known methods They have developed a complexone dimensional architecture comprising of at least 200independent electrical nanowire assemblies and have usedthem to perform a low level detection of serum-bone cancerantigens [46] For the best analysis of rationale behind usingnanowires or knowing about their qualities that can improvesensing mechanism Yang et al provided a valuable insightby rigorously talking about nanowires and nanobelts as wellas their structural aspects and features through which theycan be used in sensing applications [50] In a couple ofrelated advancements both Cui et al and Huang et al haveexplored the salient attributes of nanowires and explainedtheir utility in better conduction and detection of biologicalstimulus [51 52] Huang et al have particularly focused onsurface plasmon resonance ability of nanowires throughwhich these can be incorporated into the sensing probesand significantly improve the sensitivity of sensing eventTo make the process little more simplified Stern et alhave developed nanowires through the complementarymetaloxide semiconductor (CMOS) approach This approach has

proved to be very easy in terms of controlling and regulatingthe synthesis procedures for nanowires and has been used foranalysis of serum fluids so as to enable the isolation of severalpathogens and proteins in crude form [53]

In this way nanomaterials have proved to be highlyprosperous for brightening the sensing technology and haveimproved the diagnostic and detection procedures by leapsand bounds The faster and quicker diagnosis enabled by stillfaster analysis and evaluation protocols through the nano-materials has just revolutionized the biosensing mechanismThere are many other nanomaterials except those mentionedabove that have been capitalized upon and made use of inbiosensing applications Nanodots resembling the morphol-ogy of quantum dots nanosheets and many other structuresof altered geometries such as nanocombs nanobelts andnanoribbons have been used for improving the conventionalprocedures of sensing The coupling of piezoelectric andcantilever systems has further added a new charm to thistechnology Nanomaterials like quantum dots have beenadded as labels coupled with sensitive dyes and they haveyielded thermochromic photochromic and electro chromicmaterials which can show highly sensitive detections thatcan be monitored easily They have significantly helped inimproving electron transport mechanisms and also in thedevelopment of much more efficient actuating mechanismsto impose a particular state of observation on a system Thetext ahead mentions some impact provoking applications ofnanobiosensors in the different walks of life

6 Applications of Nanobiosensors

The definition and description of the concept of operation ofnanobiosensors do not leave any room for their applicationsas they are highly versatile and multifunctional so many andperhaps endless From the estimation and diagnosis in thehealth related in vivo aspects biosensors can also be usedfor environmental monitoring of pollutants toxicants andphysical aspects like humidity heavy metal toxicity and evenpresence of carcinogens

(1) Biomedical and Diagnostic Applications Biosensors havebeen used for biological detection of serum antigens andcarcinogens and causative agents of so many metabolicdisorders since time immemorial The routine applicationsin diagnosis are best described by the use of biosensorsin the detection of disorders like diabetes cancer allergicresponses and so many other disorders on the basis of serumanalysis To talk about most of the studied and effectualapplications of nanobiosensors from clinical point of viewthere are numerous clinical applications that are principallybeing enabled using biosensors in routineThese applicationsinclude the detection of glucose in diabetic patients [5455] detection of urinary tract bacterial infections [47 56]detection of HIV-AIDS [57 58] and the diagnosis of cancer[59ndash61] Indeed all of these are highly critical health problemsaffecting the mankind at present throughout the world Priorto the use of biosensors the detection and diagnosis of thesediseases were very difficult time consuming and costly Theadvent of biosensors has really improved the diagnosis of all


these diseases and related malfunctions With the additionof nanoscale interventions this diagnosis has further beenbenefitted and made more precise The incorporation ofnanomaterials has enabled the detecting enzyme systems tobe immobilized and this has allowed the recycling and reuseof costly enzymes Besides they have improved sensitivityand accuracies that make them hot candidates for beingtapped upon The implementation of nanoscale innovationslike NEMS and MEMS has enabled several advantages tothe overall testing procedures Extremely sensitive inroadslike those of lab-on-a-chip based assays have been developedusing smart sensing nanoscale materials only Biochips andmicroarray based testing have enabled the testing of morethan one disease in perhaps no timeWith controlled synthe-sis even magnetic nanoparticles have been synthesized andused for isolating and heavy metals resembling in propertieswith iron from the blood serum of living organisms Theevaluation of biochemical responses has been highly versatileand it has been so selective with the use of magneticnanoparticles This argues well for blood related disordersconsidering the involvement of iron protein hemoglobinSuch invasions have been collectively termed as diagnosticmagnetic resonance as they use the optimization of magneticcoupling to the in vivo antigens of the body [62] Much moresophisticated responses have been observed for detection viananobiosensors using different ways of their incorporation insensing mechanisms

(2) Environmental Applications This is a relatively broaderarea of application This is so as environment undergoes somany rapid scale changes almost every secondThe detectionof pollutants toxic intermediates heavy metals from wastestreams and the monitoring of weather conditions like theestimation of humidity and many other vital features arereally highly detailed and comprehensive tasks The sensorsbased on nanomaterials can be very versatile in terms oftheir detection and monitoring The use of devices such ascantilever based electronic probes and the provisions whichrequire very little amount of analyte are very good invadersof the technology The nanomaterials based sensing toolscan be used to find the particular kind of damaging extentof a material present or prevailing in the environment Inone such study a Chinese hamster ovary cell line has beencoupledwith fluorescent reporter system and used tomonitorvarious toxicants in highly diverse aqueous environmentsCarcinogens and harmful intermediates leading to the dis-ruption of proper hormonal systems in the living beingshave been isolated through the use of highly sophisticatedand specific compounds particularly named as endocrine-disrupting compounds [63] Similarly in one such studyPurohit et al have used biosensors to monitor the abioticconditions that are essential for optimization of biologicalrecovery applications like those of bioremediation [64] Inthis way the technique of bioremediation can be scaledup and used to optimize the environmental quality anddecontaminate the hazardous contaminants These applica-tions when engineered with the use of nanomaterials can befar more useful and beneficial Using the substrate specificdetection mechanism biosensors have been developed for

detection of nitrates [65] inorganic phosphates [66 67] andbiological oxygen demand like parameters and have beenproved to be environmentally restoring in their workingmechanisms These applications can be integrated and asingle sensor can be developed by the use of nanomaterialswhich can sense the different contaminants equally well inonly a single operation In this manner there are endlessenvironmental parameters for the evaluation of which thenanobiosensors can be used and developed These applica-tions are highly energy saving economical and time savingin nature

(3) Miscellaneous Applications Nanobiosensors can also beemployed to optimize several other detections In the indus-trial operations feeding of nutrient media and substratemixtures into the bioreactors for diverse applications can beregulated using these sensors On an industrial scale manycommercial preparations and separations can be enhancedwith these sensors For instance in the metallurgical oper-ations requiring separation of impurities existing in a com-plexed form combined in the form of ores nanobiosen-sors can be used to separate the impurities selectively bytrying out different configurations of the sensing enzymesDeveloping microbiological and biochemical assays coupledwith bioengineering based innovations are really very handyapplications of these sensing materials

7 Conclusion and Future Prospects

Nanotechnology has really proved to be a very signif-icant blessing in the development of biosensors It hasrevolutionized the case of biological detection The over-all mechanisms have become quicker smarter less costlyand user friendly The transduction mechanisms have beensignificantly improved with the use of nanomaterials andnanostructures like those of quantum dots nanoparticlesfor enzyme immobilization and hybrid nanostructures withmultiple functionalities Future argues very well for thesedynamic versatile and quick recognition systems consid-ering their multidimensional potential These materials areright now being increasingly considered for the merging ofchemical and biological sensors to make the overall processfast easy to execute and better in terms of performance[68 69] The increasing advancement of miniaturizationand nanomaterials research has stimulated the applicationof these materials for sensing several key pathways andregulatory events With the current progress and exhaustiveresearch pace of nanomaterial exploration the sensing tech-nology has become more and more versatile robust anddynamic No doubt biosensor development for a task is stillvery cumbersome and costly due to its technical complexitiesbut the incorporation of nanomaterials has proved to be a bigboon for this technology chiefly due to its friendly and resultoriented experimental support

References

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Biocapteurs enzymatiques a transduction amperometriquepasse present futurrdquo Intermediate-Range Ballistic Missile vol29 pp 171ndash180 2008

[2] P T Kissinger ldquoBiosensorsmdasha perspectiverdquo Biosensors andBioelectronics vol 20 no 12 pp 2512ndash2516 2005

[3] C Jianrong M Yuqing H Nongyue W Xiaohua and L SijiaoldquoNanotechnology and biosensorsrdquo Biotechnology Advances vol22 no 7 pp 505ndash518 2004

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[5] S Sotiropoulou V Gavalas V Vamvakaki and N A Chanio-takis ldquoNovel carbonmaterials in biosensor systemsrdquo Biosensorsand Bioelectronics vol 18 no 2-3 pp 211ndash215 2003

[6] Y-D Zhao W-D Zhang H Chen Q-M Luo and S F Y LildquoDirect electrochemistry of horseradish peroxidase at carbonnanotube powdermicroelectroderdquo Sensors and Actuators B vol87 no 1 pp 168ndash172 2002

[7] X Luo A Morrin A J Killard and M R Smyth ldquoApplicationof nanoparticles in electrochemical sensors and biosensorsrdquoElectroanalysis vol 18 no 4 pp 319ndash326 2006

[8] E Katz I Willner and J Wang ldquoElectroanalytical and bio-electroanalytical systems based on metal and semiconductornanoparticlesrdquo Electroanalysis vol 16 no 1-2 pp 19ndash44 2004

[9] J Wang ldquoNanoparticle-based electrochemical DNA detectionrdquoAnalytica Chimica Acta vol 500 no 1-2 pp 247ndash257 2003

[10] A Merkoci M Aldavert S Marın et al ldquoNew materials forelectrochemical sensing V nanoparticles for DNA labelingrdquoTrAC Trends in Analytical Chemistry vol 24 pp 341ndash349 2005

[11] J Wang G Liu R Polsky and A Merkoci ldquoElectrochemicalstripping detection of DNA hybridization based on cadmiumsulfide nanoparticle tagsrdquo Electrochemistry Communicationsvol 4 no 9 pp 722ndash726 2002

[12] N Zhu A Zhang P He and Y Fang ldquoCadmium sulfidenanocluster-based electrochemical stripping detection of DNAhybridizationrdquo Analyst vol 128 no 3 pp 260ndash264 2003

[13] Y Huang W Zhang H Xiao and G Li ldquoAn electrochemicalinvestigation of glucose oxidase at aCdSnanoparticlesmodifiedelectroderdquo Biosensors and Bioelectronics vol 21 no 5 pp 817ndash821 2005

[14] Y Cui Q Wei H Park and C M Lieber ldquoNanowire nanosen-sors for highly sensitive and selective detection of biologicaland chemical speciesrdquo Science vol 293 no 5533 pp 1289ndash12922001

[15] E Stern J F Klemic D A Routenberg et al ldquoLabel-free immunodetection with CMOS-compatible semiconduct-ing nanowiresrdquo Nature vol 445 no 7127 pp 519ndash522 2007

[16] R MacKenzie V Auzelyte S Olliges et al ldquoNanowire devel-opment and characterization for applications in biosensingrdquoNanosystems Design and Technology pp 143ndash173 2009

[17] F A Rahim Tunable Surface Assembly of Gold Nanorods forBiosensor Applications Division of Bioengineering NanyangTechnological University

[18] A V Kabashin P Evans S Pastkovsky et al ldquoPlasmonicnanorod metamaterials for biosensingrdquo Nature Materials vol8 no 11 pp 867ndash871 2009

[19] S Ramanathan S Patibandla S Bandyopadhyay J D Edwardsand J Anderson ldquoFluorescence and infrared spectroscopy ofelectrochemically self assembled ZnO nanowires evidence ofthe quantum confined Stark effectrdquo Journal of Materials Sciencevol 17 no 9 pp 651ndash655 2006

[20] L Chen B Gu G Zhu Y Wu S Liu and C Xu ldquoElectrontransfer properties and electrocatalytic behavior of tyrosinaseon ZnO nanorodrdquo Journal of Electroanalytical Chemistry vol617 no 1 pp 7ndash13 2008

[21] F Qu M Yang Y Lu G Shen and R Yu ldquoAmperometricdetermination of bovine insulin based on synergic action ofcarbon nanotubes and cobalt hexacyanoferrate nanoparticlesstabilized by EDTArdquo Analytical and Bioanalytical Chemistryvol 386 no 2 pp 228ndash234 2006

[22] P Van Gerwen W Laureyn W Laureys et al ldquoNanoscaledinterdigitated electrode arrays for biochemical sensorsrdquo Sensorsand Actuators B vol B49 no 1-2 pp 73ndash80 1998

[23] S C Pak W Penrose and P J Hesketh ldquoAn ultrathin platinumfilm sensor to measure biomolecular bindingrdquo Biosensors andBioelectronics vol 16 no 6 pp 371ndash379 2001

[24] B Bhushan ldquoNanotribology and nanomechanics of MEMSNEMS and BioMEMSBioNEMSmaterials and devicesrdquoMicro-electronic Engineering vol 84 no 3 pp 387ndash412 2007

[25] S Zeng K-T Yong I Roy X-Q Dinh X Yu and F LuanldquoA review on functionalized gold nanoparticles for biosensingapplicationsrdquo Plasmonics vol 6 no 3 pp 491ndash506 2011

[26] K L Kelly E Coronado L L Zhao and G C Schatz ldquoTheoptical properties of metal nanoparticles the influence ofsize shape and dielectric environmentrdquo Journal of PhysicalChemistry B vol 107 no 3 pp 668ndash677 2003

[27] A J Haes and R P Van Duyne ldquoA nanoscale optical biosensorsensitivity and selectivity of an approach based on the localizedsurface plasmon resonance spectroscopy of triangular silvernanoparticlesrdquo Journal of the American Chemical Society vol124 no 35 pp 10596ndash10604 2002

[28] N Nath and A Chilkoti ldquoA colorimetric gold nanoparticlesensor to interrogate biomolecular interactions in real time on asurfacerdquo Analytical Chemistry vol 74 no 3 pp 504ndash509 2002

[29] R Chakrabarti and A M Klibanov ldquoNanocrystals modifiedwith peptide nucleic acids (PNAs) for selective self-assemblyand DNA detectionrdquo Journal of the American Chemical Societyvol 125 no 41 pp 12531ndash12540 2003

[30] J I Reyes De Corcuera and R P Cavalieri ldquoEncyclopedia ofAgricultural Food and Biological Engineeringrdquo

[31] X Su F T Chew and S F Y Li ldquoDesign and applicationof piezoelectric quartz crystal-based immunoassayrdquo AnalyticalSciences vol 16 no 2 pp 107ndash114 2000

[32] T Liu J Tang and L Jiang ldquoThe enhancement effect of goldnanoparticles as a surface modifier on DNA sensor sensitivityrdquoBiochemical and Biophysical Research Communications vol 313no 1 pp 3ndash7 2004

[33] J Richardson P Hawkins and R Luxton ldquoThe use of coatedparamagnetic particles as a physical label in a magneto-immunoassayrdquo Biosensors and Bioelectronics vol 16 no 9ndash12pp 989ndash993 2001

[34] Y R Chemla H L Grossman Y Poon et al ldquoUltrasensitivemagnetic biosensor for homogeneous immunoassayrdquo Proceed-ings of the National Academy of Sciences of the United States ofAmerica vol 97 no 26 pp 14268ndash14272 2000

[35] H Cai C Xu P He and Y Fang ldquoColloid Au-enhanced DNAimmobilization for the electrochemical detection of sequence-specific DNArdquo Journal of Electroanalytical Chemistry vol 510no 1-2 pp 78ndash85 2001

[36] A L Crumbliss S C Perine J Stonehuerner K R Tubergen JZhao and R W Henkens ldquoColloidal gold as a biocompatibleimmobilization matrix suitable for the fabrication of enzyme


electrodes by electrodepositionrdquo Biotechnology and Bioengi-neering vol 40 no 4 pp 483ndash490 1992

[37] J Zhao J P OrsquoDaly R W Henkens J Stonehuerner andA L Crumbliss ldquoA xanthine oxidasecolloidal gold enzymeelectrode for amperometric biosensor applicationsrdquo Biosensorsand Bioelectronics vol 11 no 5 pp 493ndash502 1996

[38] X Xu S Liu and H Ju ldquoA novel hydrogen peroxide sensor viathe direct electrochemistry of horseradish peroxidase immo-bilized on colloidal gold modified screen-printed electroderdquoSensors vol 3 no 9 pp 350ndash360 2003

[39] M L Curri A Agostiano G Leo AMallardi P Cosma andMDellaMonica ldquoDevelopment of a novel enzymesemiconductornanoparticles system for biosensor applicationrdquo Materials Sci-ence and Engineering C vol 22 no 2 pp 449ndash452 2002

[40] M B Gonzalez-Garcıa C Fernandez-Sanchez and ACosta-Garcıa ldquoColloidal gold as an electrochemical label ofstreptavidinmdashbiotin interactionrdquo Biosensors and Bioelectronicsvol 15 no 5-6 pp 315ndash321 2000



[43] B R Azamian J J Davis K S Coleman C B Bagshawand M L H Green ldquoBioelectrochemical single-walled carbonnanotubesrdquo Journal of the American Chemical Society vol 124no 43 pp 12664ndash12665 2002

[44] A Guiseppi-Elie C Lei and R H Baughman ldquoDirect electrontransfer of glucose oxidase on carbon nanotubesrdquoNanotechnol-ogy vol 13 no 5 pp 559ndash564 2002

[45] J Wang ldquoCarbon-nanotube based electrochemical biosensorsa reviewrdquo Electroanalysis vol 17 no 1 pp 7ndash14 2005

[46] Y Cui and C M Lieber ldquoFunctional nanoscale electronicdevices assembled using silicon nanowire building blocksrdquoScience vol 291 no 5505 pp 851ndash853 2001

[47] J Wang ldquoElectrochemical nucleic acid biosensorsrdquo AnalyticaChimica Acta vol 469 no 1 pp 63ndash71 2002

[48] B M Cullum G D Griffin G H Miller and T Vo-DinhldquoIntracellular measurements in mammary carcinoma cellsusing fiber-optic nanosensorsrdquoAnalytical Biochemistry vol 277no 1 pp 25ndash32 2000

[49] A UmarMM Rahman A Al-Hajry and Y-B Hahn ldquoHighly-sensitive cholesterol biosensor based on well-crystallizedflower-shaped ZnO nanostructuresrdquo Talanta vol 78 no 1 pp284ndash289 2009

[50] S Yang ldquoNanowires and nanobelts materials properties anddevicesrdquo inNanowires and Nanobelts of Functional Materials ZL Wang Ed vol 2 pp 209ndash238 Kluwer Academic New YorkNY USA 2003


[52] B Huang F Yu and R N Zare ldquoSurface plasmon resonanceimaging using a high numerical aperturemicroscope objectiverdquoAnalytical Chemistry vol 79 no 7 pp 2979ndash2983 2007


[54] J C Pickup F Hussain N D Evans and N Sachedina ldquoInvivo glucose monitoring the clinical reality and the promiserdquoBiosensors andBioelectronics vol 20 no 10 pp 1897ndash1902 2005

[55] J Bolinder U Ungerstedt and P Arner ldquoMicrodialysis mea-surement of the absolute glucose concentration in subcutaneousadipose tissue allowing glucosemonitoring in diabetic patientsrdquoDiabetologia vol 35 no 12 pp 1177ndash1180 1992

[56] T G DrummondMGHill and J K Barton ldquoElectrochemicalDNA sensorsrdquoNature Biotechnology vol 21 pp 1192ndash1199 2003

[57] L G Fagerstam A Frostell R Karlsson et al ldquoDetection ofantigen-antibody interactions by surface plasmon resonanceApplication to epitope mappingrdquo Journal of Molecular Recog-nition vol 3 no 5-6 pp 208ndash214 1990

[58] M Alterman H Sjobom P Safsten et al ldquoP1P11015840modifiedHIVprotease inhibitors as tools in two new sensitive surface plas-mon resonance biosensor screening assaysrdquo European Journalof Pharmaceutical Sciences vol 13 no 2 pp 203ndash212 2001

[59] X Gao Y Cui R M Levenson L W K Chung and S NieldquoIn vivo cancer targeting and imaging with semiconductorquantum dotsrdquo Nature Biotechnology vol 22 no 8 pp 969ndash976 2004

[60] M G Harisinghani J Barentsz P F Hahn et al ldquoNoninvasivedetection of clinically occult lymph-nodemetastases in prostatecancerrdquo The New England Journal of Medicine vol 348 no 25pp 2491ndash2499 2003

[61] J Grimm J M Perez L Josephson and R Weissleder ldquoNovelnanosensors for rapid analysis of telomerase activityrdquo CancerResearch vol 64 no 2 pp 639ndash643 2004

[62] J B Haun T-J Yoon H Lee and R Weissleder ldquoMagneticnanoparticle biosensorsrdquoWiley Interdisciplinary Reviews vol 2no 3 pp 291ndash304 2010

[63] E J KimY Lee J E Lee andMBGu ldquoApplication of recombi-nant fluorescentmammalian cells as a toxicity biosensorrdquoWaterScience and Technology vol 46 no 3 pp 51ndash56 2002

[64] H J Purohit ldquoBiosensors as molecular tools for use in bioreme-diationrdquo Journal of Cleaner Production vol 11 no 3 pp 293ndash301 2003

[65] L H Larsen T Kjaeligr and N P Revsbech ldquoA microscaleNO3- biosensor for environmental applicationsrdquo Analytical

Chemistry vol 69 no 17 pp 3527ndash3531 1997[66] J Kulys I J Higgins and J V Bannister ldquoAmperometric

determination of phosphate ions by biosensorrdquo Biosensors andBioelectronics vol 7 no 3 pp 187ndash191 1992

[67] U Wollenberger F Schubert and F W Scheller ldquoBiosensor forsensitive phosphate detectionrdquo Sensors and Actuators B vol 7no 1ndash3 pp 412ndash415 1992

[68] J Ponmozhi C Frias T Marques and O Frazao ldquoSmartsensorsactuators for biomedical applications reviewrdquo Mea-surement vol 45 no 7 pp 1675ndash1688 2012

[69] T Pradeep andAAnshup ldquoNoblemetal nanoparticles forwaterpurification a critical reviewrdquo Thin Solid Films vol 517 no 24pp 6441ndash6478 2009

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of



CeramicsJournal of


CompositesJournal of

NanoparticlesJournal of



International Journal of

Biomaterials


NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials


analyzes)

Biosensor components (in order)

Bioreceptor(material which

Transducer(signal

conversion)

Detector (reproducible

response)

Figure 1 Depiction of the block diagram of a biosensor

2 Definition and Conceptual Idea

A biosensor can be defined as a sensing device or a measure-ment system designed specifically for estimation of a mate-rial by using the biological interactions and then assessingthese interactions into a readable form with the help of atransduction and electromechanical interpretation Figure 1gives us information about the three main components of abiosensor In terms of the conceptual and fundamental modeof operation these components are namely bioreceptortransducer and the detector The main function or purposeof a biosensor is to sense a biologically specific materialOften these materials are antibodies proteins enzymesimmunological molecules and so on

It is done by using another biologically sensitive materialthat takes part in the making of bioreceptor So a bioreceptoris that component of a biosensor which serves as a templatefor the material to be detectedThere can be several materialswhich can be used as bioreceptors For instance an antibodyis screened using antigen and vice versa a protein is screenedusing its corresponding selective substrate and so on Thesecond component is the transducer system The main func-tion of this device is to convert the interaction of bioanalyteand its corresponding bioreceptor into an electrical formThe name itself defines the word as trans means change andducer means energy So transducer basically converts oneform of energy into another The first form is biochemical innature as it is generated by the specific interaction betweenthe bioanalyte and bioreceptor while the second form isusually electrical in nature This conversion of biochemicalresponse into electrical signal is achieved through transducerThe third component is the detector system This receivesthe electrical signal from the transducer component andamplifies it suitably so that the corresponding response can beread and studied properly In addition to these componentsa very essential requirement of the nanobiosensors is theavailability of immobilization schemes which can be used toimmobilize the bioreceptor so as to make its reaction withbioanalyte much more feasible and efficient Immobilizationmakes the overall process of biological sensing cheaper andthe performance of the systems based on this technology isalso affected by changes in temperature pH interference bycontaminants and other physicochemical variations [2]

3 Nanobiosensors The Merging ofNanotechnology with Biosensors

The understanding of biosensing concept lays the foun-dation for studying and developing the nanobiosensorsNanobiosensors are basically the sensors which are madeup of nanomaterials and interestingly these are not thespecialized sensors which can detect the nanoscale eventsand happenings The question that sustains interest from theabove description is that why nanomaterials are intended tobe used in making biosensors or whether they are going todrive in any significant difference in the overall technologyNanomaterials are a unique gift of nanotechnology to themankind these are the materials which have one of theirdimensions between 1 and 100 nanometers The size con-straints of these materials makes them very special as theyhave most of their constituent atoms located at or near theirsurface and have all vital physicochemical properties highlydifferent from the same materials at the bulk scale Theycan play very efficient roles in the sensing mechanism of thebiosensor technology Integrated devices of the nanomateri-als with electrical systems give rise to nanoelectromechanicalsystems (NEMS) which are very active in their electricaltransduction mechanisms Several nanomaterials have beenexplored on the basis of their electronic and mechanicalproperties for their use in improved biological signaling andtransduction mechanisms Some of such materials that arewidely employed include nanotubes nanowires nanorodsnanoparticles and thin films made up of nanocrystallinematter [3] Amongst these the use of nanoparticles is beststudied and analyzed till date Nanobiosensors have servedas very potent developmental inroads in the biosensor tech-nology which has been possible only due to the wondersof nanotechnological implications of the matter A widevariety of biosensing devices that employ nanoparticles ornanostructures have been investigated in a number of studiesthroughout the world These can be as diverse as usingamperometric devices for enzymatic detection of glucose tousing quantum dots as fluorescence agents for the detectionof binding and even using bioconjugated nanomaterialsfor specific biomolecular detection These include colloidalnanoparticles which can be used to conjugate with antibodiesfor immunosensing and immunolabelling applicationsThesematerials can also be used to enhance the electron micro-scopic detections Furthermetal based nanoparticles are veryexcellent materials for electronic and optical applications andcan be efficiently used for detection of nucleic acid sequencesthrough the exploitation of their optoelectronic properties

Table 1 shows the main types of nanomaterials beingemployed for further improvising upon the sensing mecha-nisms that are conventionally being employed in the biosen-sor technology It highlights the potential advantages of sev-eral nanomaterials employed and some evidence witnessedtheir use so far (encoded by corresponding references)The details of different biosensors developed by the use ofdifferent materials at the nanoscale are mentioned further inthe text Even magnetic nanoparticles made up of iron andits oxides have been used for specific and efficient detectionof magnetism based events and interactions like those of




(1)Carbon

nanotubes


[4ndash6]

(2) nanoparticles


[7ndash10]

(3)Quantum

dots


[11ndash13]

(4) Nanowires


[14ndash16]

(5) Nanorods


[17ndash19]








































References


















































































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






(1)Carbon

nanotubes


[4ndash6]

(2) nanoparticles


[7ndash10]

(3)Quantum

dots


[11ndash13]

(4) Nanowires


[14ndash16]

(5) Nanorods


[17ndash19]








































References


















































































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



































References


















































































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



















































































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



review article nanobiosensors: concepts and variations · 2019. 7. 31. · nanobiosensors: concepts...

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