Controlled Fabrication of Functional Capsules Based on theSynergistic Interaction between Polyphenols and MOFs under WeakBasic ConditionHui Wang,†,‡,⊥ Wei Zhu,†,‡,§ Yuan Ping,†,∥,# Chen Wang,‡ Ning Gao,‡ Xianpeng Yin,‡ Chen Gu,‡

Dan Ding,¶ C. Jeffrey Brinker,*,§ and Guangtao Li*,‡

‡Key Lab of Organic Optoelectronic and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 10084,People’s Republic of China§Advanced Materials Laboratory, Sandia National Laboratories, Albuquerque, New Mexico 87185, United States⊥College of Chemical Engineering, Shijiazhuang University, Shijiazhuang 050035, P. R. China∥School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore#School of Pharmaceutical Sciences, Higher Education Mega Center, Sun Yat-Sen University, Panyu, Guangzhou 510006, China¶State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin 300071, People’s Republic of China

*S Supporting Information

ABSTRACT: Metal−organic coordination materials with controllable nanostructures are of widespread interest due to thecoupled benefits of inorganic/organic building blocks and desired architectures. In this work, based on the finding of a synergisticinteraction between metal−organic frameworks (MOFs) and natural polyphenols under weak basic condition, a facile strategyhas been developed for directly fabricating diverse phenolic-inspired functional materials or metal-phenolic frameworks (MPFs)with controlled hollow nanostructures (polyhedral core−shell, rattle-like, hollow cage, etc.) and controllable size, morphology,and roughness, as well as composition. By further incorporating the diverse functionalities of polyphenols such as low toxicity andtherapeutic properties, catalytic activity, and ability to serve as carbon precursors, into the novel assemblies, diverse artificiallydesigned nanoarchitectures with target functionalities have been generated for an array of applications.

KEYWORDS: polyphenol, metal−organic framework, synergistic interaction, capsule, nanostructure

1. INTRODUCTION

Metal−organic coordination materials with hollow nanostruc-tures have spurred considerable interest because of their uniquestructure-/composition-dependent properties, such as selectivepermeability, high mechanical strength, good thermal stability,adjustable pH-responsive disassembly, etc.1−6 Up to now,numerous methods including liquid−liquid interfacial growth,1

spray-drying,2 and sacrificial template-mediated etching strat-egies4−7 have been developed to fabricate the hollownanoarchitectures based on metal-coordination interactions.Specifically, metal−organic frameworks (MOFs),8−17 formedby the association of metal ions/clusters and organic ligands,have been recently proposed as an effective sacrificial template

to construct hollow nanostructures. So far, a wide range ofexamples such as single-compositional Fe(OH)3 microboxes,multicompositional SnO2−Fe2O3 microboxes, double-shelledCo3O4−NiCo2O4 nanostructured cages, and bimetallic sulfideMxCo3-xS4 hollow polyhedrons have been reported based onMOF-template engaged strategies.18−20 Whereas, many currentstudies mainly focused on formation of inorganic hollowmaterials, the construction of MOF-inspired metal−organiccoordination materials with controlled hollow structures and

Received: February 8, 2017Accepted: April 11, 2017Published: April 11, 2017

Research Article

www.acsami.org

© 2017 American Chemical Society 14258 DOI: 10.1021/acsami.7b01788ACS Appl. Mater. Interfaces 2017, 9, 14258−14264

the further integration of highly functionalities of organicligands into the novel assemblies for targeted functions is lesswell studied but of potentially high interest.Polyphenols, a structural class of natural organic chemicals

consisting of large multiples of phenolic structural units, areubiquitous and diverse in nature.5,21 Because of their uniquefeatures (antioxidant, anticarcinogenic, therapeutic, etc.), theyoffer various applications in biological systems, such as servingas scavengers of free redicals to promote human health,mediating cell-to-cell signaling, and perturbing the associationof certain proteins into toxic arrangements.22,23 Furthermore,because of their ability to coordinate with metals, polyphenolscould also be used as building blocks to fabricate exoticstructures with advanced functionalities.24−30 Along these lines,the Tsukruk group incorporated tannins into capsulemembranes to confer antioxidant and metal-reducing proper-ties.24 The Messersmith group described the use of plantpolyphenols for multifunctional coatings,25 and most recently,the Caruso group reported the synthesis of hollow MOFs withthe assistance of phenolic acid binding to the outlayer surface26

and the fabricated capsules were employed for drug deliveryand biomedical imaging.27 Nevertheless, until now the

fabrication of phenolic-based or phenolic-inspired functionalmaterials remains in its infancy.31

Here, we present a novel strategy to prepare functional MPFswith controllable nanostructures based on a simple combina-tion of natural polyphenols and MOFs (Scheme 1). The keypoint is the synergistic interactions between polyphenols andMOFs under weak basic condition. On one side, due to thehigher priority of phenol units for metal-coordination,polyphenol molecules adsorb conformally to the MOF surfaceand then progressively replace the original organic linkers fromthe exterior to the interior. On the other side, the reducedstability of the parent MOF templates in basic solution speedsthe etching and replacement process. This newly discoveredsynergistic effect provides an opportunity to directly fabricatediverse phenolic-inspired functional materials for wideapplications. Especially, this strategy is generally applicable fordifferent MOFs. As a demonstration, through careful control ofboth etching time and pH conditions, we have synthesized avariety of novel nanoarchitectures with tunable surfaceroughness and hollow interiors including polyhedral core−shell, rattle-like, and hollow cages, and even complexmultishelled structures. Moreover, the great variety of

Scheme 1. Schematic Illustration of the Construction of Phenolic-Inspired Functional Materials by Template-EngagedCoordination Etching of MOF Nanoparticles

Figure 1. TEM and SEM image of (a, b) ZIF-8 crystals and (c, d) Zn-EA hollow cages; (e) EDX elemental mapping of Zn-EA hollow cages. Scalebar is 500 nm in e. (f) Wide-angle PXRD patterns of the simulated ZIF-8 crystals, as-synthesized ZIF-8 nanoparticles (1), and core−shell (2),rattlelike (3), and hollow (4) Zn-EA cages.

ACS Applied Materials & Interfaces Research Article

DOI: 10.1021/acsami.7b01788ACS Appl. Mater. Interfaces 2017, 9, 14258−14264

14259

polyphenols (>4000 species) combined with the diverse rangeof MOFs promise infinite combinations. By incorporating thediverse functionalities of polyphenols (low toxicity andtherapeutic property, catalytic activity, and ability to serve ascarbon precursors) into the novel assemblies, various artificiallydesigned nanoarchitectures with target functionalities have alsobeen generated for an array of applications, including catalysis,drug delivery, biomedical imaging, and the further generation offunctional nanoporous carbons. We believe our new strategywould not only bridge the field of phenolic-based materials withinfinite MOFs but also open new avenues for artificiallydesigned phenolic-inspired nanoarchitectures with targetfunctionalities.

2. RESULT AND DISCUSSIONMPFs with hollow structures were formed simply by mixingMOF particles and natural polyphenols in basic solution. Todemonstrate the structure replication process, we first usedZIF-8 particles as sacrificial templates and ellagic acid (EA) asan etching agent. EA, a well-known natural polyphenol found infruits and vegetables, shows strong, divalent coordinationbinding to various metal ions. Polyhedra ZIF-8 particles withsize of 2.6 μm were synthesized according to literatureprocedures.32 Scanning electron microscopy (SEM), trans-mission electron microscopy (TEM), and wide-angle X-raydiffraction (XRD) confirmed the well-defined rhombicdodecahedral shape with cubic I4 3 m space group (Figure 1a,b, f). After the addition of ZIF-8 particles into an EA containingsolution under basic conditions, phenol coordination of metalaccompanied by etching/dissolution of the sacrificial MOF coreresulted after 4 h in polyhedra hollow cages that replicate theparent MOF (Figure 1c, d). The shell thickness was ∼100 nm(Figure 1d). Fourier transform infrared spectrophotometry(FT-IR) of the Zn2+-EA cage proved the metal-phenoliccoordination by the disappearance of characteristic O−Hvibration peaks of the EA (3500 cm−1) and the almostdisplacement of imidazole linkers, as evidenced by the absenceof the entire ring stretching band in the range 1350−1500 cm−1

(Figure S1). Energy-dispersive X-ray (EDX) mapping analysisdemonstrated that the Zn2+ distribution patterns matched wellwith high-angle annular dark-field images (HAADF) and thedistribution of C and O maps (Figure 1e), while the N elementwas absent after etching (Figure S2). Compared with theamorphous films resulting from direct metal-phenolic coordi-nation, the MPFs in our case still maintained partially orderedarrangements, analogous to graphite (Figure 1f).27 Todetermine the BET surface area and pore volume of theprepared polyphenol capsules, standard nitrogen adsorption−desorption measurement was also carried out. However, due tothe soft and hollow structure of the capsules that leads to thecollapse of the polyphenol capsules under vacuum, the BETsurface area of the hollow cage is quite low (Figure S3e, f).Nevertheless, from the HR-TEM image in Figure S3a, c, theshell of the metal-polyphenol capsules is full of pores, provingthe porous structures of the polyphenol capsules. These resultsclearly proved the top-down replication process.Because of the diverse metal-chelation abilities of polyphenol,

our top-down etching strategy should be also suitable for otherMOF systems, such as ZIF-67, prussian blue (PB), andHKUST-1 particles with different metal ions (Figure S4).Following the same etching process, MPF hollow cages withvarious morphologies, sizes, and compositions were alsoachieved (Figure 2 and Figure S5). Furthermore, compounds

showing multivalent binding to metal ions as an etching agent,similar etching behaviors were also observed resulting in MPFhollow cages (Figure S6). Additionally, as a control experiment,MOF nanostructured particles were also soaked in basic buffersolutions at different pH without polyphenols. We found thatwith increasing pH, the MOF surface became rougher (FigureS7), indicating the reduced stability of the parent MOF oreasier cleavage of metal−organic coordination bonds in basicconditions. On the other side, the etching of MOF particles inpolyphenol solutions under neutral condition exhibits a quiteslow etching rate (Figure S8). Also by adding differentinorganic salts in the etching solution, the similar hollowstructures could also been achieved (Figure S9), indicating theionic strength has no influence on the final structure during theetching process. These above observations clearly proved thesynergistic interaction between MOF and polyphenol. Summa-rizing, we believe the fundamental driving force for creatinghollow cavities is the higher binding affinities between phenolunits and metal ions and the reduced stability of the MOFtemplate in basic solution. Because of the porous structure ofincipient two-dimensional (2D) EA-metal networks or 3D TA-metal networks,33 the inward diffusion of phenolic moleculesand outward diffusion of metal ions and previous organiclinkers allow the formation of MPFs with hollow structures.Further, we can systematically vary the diffusion-controlledetching process allows us to tune the hollow interiors. Due tothe short etching time, EA molecules have a short diffusionlength and so ZIF-8@Zn-EA MPF with a core−shell structurewas achieved (Figure 3a). The relative intensity and peakpositions in XRD patterns (Figure 1f) are in agreement withthe simulated one, further confirming the obtained inwardetching process (Figure 3b, c). Because of the slow etchingspeed, the size of the detached interior MOF core could beprecisely controlled down to the nanoscale level (Figure S10a−c). By subsequently removing the MPF shell in organic solvent,nano-MOFs with controlled size were easily achieved (FigureS10d−f), indicating a new strategy for nano-MOF preparation.On the other hand, the pH value was found to play animportant effect, where the higher pH resulted in roughersurfaces (Figure S11). In some cases, surface roughnessstrongly influences the performance of nano-objects such as

Figure 2. TEM images of diverse MPFs with hollow structures derivedfrom (a) ZIF-67, (b) PB, and (c) HKUST-1; (d, e) ZIF-8 withdifferent sizes as sacrificial templates; polyphenol EA as etching agent.

ACS Applied Materials & Interfaces Research Article

DOI: 10.1021/acsami.7b01788ACS Appl. Mater. Interfaces 2017, 9, 14258−14264

14260

in interactions with cell surfaces.34 But to date there is noefficient method to control roughness. Here due to theindependent process of etching and surface roughnessgeneration, we have an ability to prepare phenolic-inspiredmaterials with diverse structures. Moreover, for the case of PB-type MOFs, coupled with the synergistic effect of OH− topromote the etching kinetics, the shell thickness could beprecisely controlled. As shown in Figure 3d−f, Fe3+/2+-EApolyhedra with different thicknesses from 21 to 57 nm and withphase purity (confirmed by XRD in Figure S12) were clearlyobserved. Furthermore, through use of FeFe@FeCo particleswith bilayer structure,35−37 more advanced architectures such asnanostructured boxes with multishelled structures could also besynthesized (Figure 3g−i). HR-TEM imaging showed that theshell was constructed of soft sheetlike subunits (Figure S13).Nanoscale MOFs, because of their high drug loading

capabilities, biodegradability, and versatile functionality, havebeen considered as a promising platform for drug delivery.38

Nevertheless, due to their unnegligible cytotoxicity, the numberof existing MOFs that can be applied as drug carriers are stillvery limited.39 Here, because of the nontoxic properties of thenatural polyphenols, in most cases, the replacement of theoriginal organic linkers by phenolic ligands may greatly reducecytotoxicity making the resultant phenolic-inspired MPFmaterials to be of potential interest for drug delivery. Todemonstrate the biocompatibility of MPF hollow cages,weconducted 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) assays to examine the cytotoxicity against ofJAWS II cells after 2h treatment.40 As shown in Figure 4a, forthe traditional MOF particles, HKUST-1, ZIF-8, and PB, theaverage relative cell viability (%) at a cell-to-MPF ratio of 1:25was determined to be 88.1, 79.2, and 96.4, respectively.However, after the conversion to MPF particles, except PB, therelative cell viability for HKUST-1, ZIF-8 was increased to 94.5and 89.8, respectively. Also, for other cell-to-MPF ratios (1:50;

1:75; 1:100), the cell viability (Figure S14) follows a similartrend as to that in Figure 4a, indicating the low cytotoxicity ofphenolic-based materials for drug delivery. As a proof-of-concept, drug release experiment for Zn-MPF hollow capsuleloading of fluorescein isothiocyanate (FITC) dye as a modelwas carried out in PBS buffer solution (pH 7.4) at roomtemperature. From the release curve (Figure S15), the releasespeed was steady and only ca. 11% of the loaded “drugs” wasreleased out at 24 h. The slow release may be due to the slowdiffusion rate of FITC caused by the strong interaction betweenLewis acid sites in zinc and carboxylic group of FITC.Nevertheless, the drug delivery capability of Zn-MPF hollowcages loaded with model cargo (dextran-fluorescein isothiocya-nate, FITC-dextran) was also investigated. The drug-loadedcages were incubated with JAWS II cells for different timeinterval to evaluate cellular internalization of the MPFmaterials. The cellular membranes were stained withAlexaFluor (AF) 594-wheat germ agglutinin, and the internal-ization process was verified by deconvolution fluorescencemicroscopy (Figure 4b). At the first 2 h, only a few internalizedZn-MPF cages were observed. However, after the incubationtime for 24 h, a large number of cages were effectivelyinternalized by JAWS II cells (Figure 4b). Moreover, the similarinternalization behavior can be also found for Cu- or Fe-basedMPFs by HeLa cells (Figure S16). All these informationsuggest that the uptake of drug-loaded MPF cages in our case istime-dependent and MPFs are able to deliver drugs into cellsefficiently. Because of the thicker shell (ca. 100 nm) of thecages to reinforce the mechanical strength, the majority of theinternalized hollow cages still retained their polyhedralmorphology with little deformation. Interestingly, due to thedisassembly feature of metal-phenolic network under weaklyacidic conditions, the disassembled feature of Zn-MPF cagescould also be observed (Figure S17). The intracellulardisassembly of MPF cages may provide the potential fortriggered drug release at intracellular endosomal or tumoracidic pH, which is of importance for advanced drug delivery.In addition, by exploring the FeIII/II, MnII, or CoII/MnII-based

Figure 3. TEM images of (a−c) ZIF-8-based MPF with polyhedracore−shell, rattlelike, and hollow cage structure; (d−f) PB-based MPFwith controlled thickness; (g) FeFe-PB particle, (h) FeFe@FeCo-PBparticle, and (i) FeFe@FeCo-based MPF with multishelled structure.

Figure 4. (a) Cell viability of JAWS II cells measured by MTT assaysfor various MOF particles and the related MPFs. (b) Fluorescencedeconvolution microscopy images of Zn-MPF hollow cages loadedwith dextran-FITC internalized by JAWS II cells at different timeintervals. The scale bars represents 15 μm. (c) MRI phantom imagesof CoMn-, Fe-, and Co-MPFs immobilized in agarose. T2-weightedspin echo images of samples with three different metal concentrations.

ACS Applied Materials & Interfaces Research Article

DOI: 10.1021/acsami.7b01788ACS Appl. Mater. Interfaces 2017, 9, 14258−14264

14261

MOFs as the template, the coordination of these metal ionsinto the MPF materials offers an opportunity for magneticresonance imaging (MRI). As a demonstration, we carried outMR relaxometry experiments with the related MPFs anddetermined their relaxivities on a 9.4 T animal MRI system(Figure 4c). As shown in Figure S18, the relaxivity r2 of CoII−MnII-MPF hollow cages reached an order of 80 ± 5 s−1 mM−1,which is higher than the other two samples and should besufficient for in vivo use.27 Combined with the drug deliverycapacity of MPFs and the potential to incorporate therapeuticproperties into MPFs, the demonstration of MRI suggestsMPFs could represent a promising new class of theranosticnanocarriers. Right now, the related work is still ongoing in ourlab.Nanostructured porous carbons (NPCs) have attracted

considerable attentions for applications in global energy andenvironmental issues.41,42 Motivated by resorcinol or dopaminethat have been used as carbon precursors, polyphenols, becauseof their abundant content in many plants, renewability,diversity, and especially low cost, should also be an excellentcandidate for carbon resources.43 In our case, through a simplethermal conversion, metal-phenolic networks with diversestructures were efficiently converted into carbons. For thecase of Co-EA hollow cages, as shown in Figure 5a, polyhedra

carbon was clearly observed. The apparent oriented multi-layered domains and graphene sheets stacked in parallel revealthe high degree of graphitization (Figure 5b). The interplane(002) spacing of the lattice is measured as 0.34 nm, inagreement with the interlayer spacing of graphite. The sharp(002) peak in XRD patterns also proves the high graphiticdegree (Figure S19). The intensity ratio (ID/IG) of the peaksroughly at 1351 cm−1 (D band) and 1591 cm−1 (G band) in theRaman spectra was calculated as 1.21 (Figure S20). All theseresults support topotactic conversion of polyphenols intocarbons. We believe that because of the partially ioniccharacteristic of the metal-phenol complex, the carbonizationprocess was efficiently promoted.42 Also using other MOFparticles as templates and following the same thermaltreatment, all the metal-phenolic cages or even the rattle-likecages in Figure 5c−f and S21 were converted into metalnanoparticles-doped NPCs with preservation of the hollow

interior. The surface area (SBET) and pore volume (Vpore) ofthese NPCs are summarized in Table S1. Obviously all thephenolic-inspired carbon materials showed high surface areas.These results clearly prove that polyphenols are good carbonsources that can be used to tailor both the nanostructures andelectronic properties of MPF-based NPCs.We further extended the investigation of phenolic-inspired

MPFs for catalysis by incorporating the polyphenol shell and adetached catalytic core to integrate the individual functions ofpermselectivity and catalysis. The gold-catalyzed reduction of 4-nitrophenol by NaBH4 to 4-aminophenol was chosen as amodel reaction to evaluate the catalytic ability of thesynthesized Au@Co-MPF rattle-type particles. As shown inFigure 6a, each ZIF-67 crystal contains several Au nanoparticles

with the diameter of 20 nm. Using the synergistic etchingprocess described previously, corresponding Au@Co-MPFnanorattles structures were obtained (Figure 6b). When theAu@Co-MPF yolk−shell catalyst was introduced to thesolution, the absorption at 400 nm quickly decreased and theabsorption at 295 nm increased accordingly (Figure 6d).Because of the enrichment effect of polyphenol for 4-nitrophenol, whose solubility in water is very low, based onπ−π hydrophobic interactions and the porous nature of theshell, 4-nitrophenol can be accumulated inside the core to allowthe fast reduction by Au nanoparticles. The reduction ofnitrobenzene into aminobenzene was completely finished at 5min, which is faster than that in Au doped ZIF-67 particle(Figure 6c and Figure S22a) and pure Co-MPF (Figure S22a).After each use, the Au@Co-MPF catalyst could be recycled bysimple centrifugation, followed by washing with distilled water,and importantly still keeps highly active even after foursuccessive cycles of reactions (Figure S22b). Also from theTEM image in Figure S23, the nanostructure of Au@Co-MPFremained almost the same, indicating the stability of the catalystfor repetitive reactions. The combined catalytic performance ofAu and the selective permeability of the MPF shell create inessence a nanoscale catalytic reactor, which could furtherpotentially avoid poisoning and coarsening of the catalyst.

Figure 5. (a, b) TEM images of C-ZIF-67-EA at differentmagnifications; (c) TEM images of ZIF-8-based NPC with core−shell structure, and NPCs with different morphologies: (d) PB, (e)HKUST-1, and (f) ZIF-8 as template. For all cases, polyphenol EA wasthe etching agent.

Figure 6. TEM images of (a) Au@ZIF-67 and (b) Au@Co-MPF, TAas etching agent; (c) photograph and (d) UV/vis spectra of the 4-nitrophenol solution after the reduction by Au@Co-MPF particles.

ACS Applied Materials & Interfaces Research Article

DOI: 10.1021/acsami.7b01788ACS Appl. Mater. Interfaces 2017, 9, 14258−14264

14262

3. CONCLUSIONIn summary, based on a synergistic interaction between MOFsand natural polyphenols under weak base condition, a facilestrategy for the direct fabrication of functional MPFs has beendeveloped. MPFs with novel structures and controllable size,morphology, roughness as well as compositions, have beensuccessfully achieved. By incorporating the diverse function-alities of polyphenols, including low toxicity and therapeuticproperties, catalytic activity, and ability to serve as carbonprecursors, into the novel assemblies, the resultant materialsshow high potential for nanoscale catalytic reactors and newclasses of theranostic nanoparticles. Different from the reportedmethods, our strategy described here is very generallyapplicable. Because of the essentially unlimited variety ofboth polyphenols and MOFs, we believe our findings shouldopen new avenues for artificially designed phenolic-inspiredfunctional materials for wide ranging applications.

■ ASSOCIATED CONTENT*S Supporting InformationThe Supporting Information is available free of charge on theACS Publications website at DOI: 10.1021/acsami.7b01788.

Experimental Section and Figures S1−S21 (PDF)

■ AUTHOR INFORMATIONCorresponding Authors*E-mail: LGT@mail.tsinghua.edu.cn.*E-mail: .cjbrink@sandia.gov.ORCIDC. Jeffrey Brinker: 0000-0002-7145-9324Guangtao Li: 0000-0003-4127-1715Author Contributions†H.W., W.Z., and Y.P. contributed equally. The manuscript waswritten through contributions of all authors. All authors havegiven approval to the final version of the manuscript.NotesThe authors declare no competing financial interest.

■ ACKNOWLEDGMENTSWe appreciate the support from the National ScienceFoundation of China (21473098, 21421064, 21121004),MOST Program (2013CB834502 and 2011CB808403) andTransregional Project (TRR61). W.Z. and C.J.B. acknowledgesupport from the U.S. DOE Office of Science, Divisions ofCatalysis and Materials Science and Engineering.

■ REFERENCES(1) Ameloot, R.; Vermoortele, F.; Vanhove, W.; Roeffaers, M. B.;Sels, B. F.; De Vos, D. E. Interfacial Synthesis of Hollow Metal−Organic Framework Capsules Demonstrating Selective Permeability.Nat. Chem. 2011, 3, 382−387.(2) Carne-Sanchez, A.; Imaz, I.; Cano-Sarabia, M.; Maspoch, D. ASpray-Drying Strategy for Synthesis of Nanoscale Metal−OrganicFrameworks And Their Assembly Into Hollow Superstructures. Nat.Chem. 2013, 5, 203−211.(3) Pang, M.; Cairns, A. J.; Liu, Y.; Belmabkhout, Y.; Zeng, H. C.;Eddaoudi, M. Synthesis and Integration of Fe-soc-MOF Cubes intoColloidosomes via a Single-Step Emulsion-Based Approach. J. Am.Chem. Soc. 2013, 135, 10234−10237.(4) Shi, J.; Zhang, L.; Jiang, Z. Facile Construction of Multicompart-ment Multienzyme System through Layer-by-Layer Self-Assembly and

Biomimetic Mineralization. ACS Appl. Mater. Interfaces 2011, 3, 881−889.(5) Ejima, H.; Richardson, J. J.; Liang, K.; Best, J. P.; van Koeverden,M. P.; Such, G. K.; Cui, J.; Caruso, F. One-Step Assembly ofCoordination Complexes for Versatile Film and Particle Engineering.Science 2013, 341, 154−156.(6) Wang, X.; Jiang, Z.; Shi, J.; Liang, Y.; Zhang, C.; Wu, H. Metal−Organic Coordination-Enabled Layer-by-Layer Self-Assembly toPrepare Hybrid Microcapsules for Efficient Enzyme Immobilization.ACS Appl. Mater. Interfaces 2012, 4, 3476−3483.(7) Lee, H. J.; Cho, W.; Oh, M. Advanced fabrication of metal−organic frameworks: template-directed formation of polystyrene@ZIF-8 core−shell and hollow ZIF-8 microspheres. Chem. Commun. 2012,48, 221−223.(8) Furukawa, H.; Cordova, K. E.; O’Keeffe, M.; Yaghi, O. M. TheChemistry and Applications of Metal-Organic Frameworks. Science2013, 341, 1230444.(9) Wang, C.; Liu, D.; Lin. Metal−Organic Frameworks as A TunablePlatform for Designing Functional Molecular Materials. W. J. Am.Chem. Soc. 2013, 135, 13222−13234.(10) Betard, A.; Fischer, R. A. Metal-Organic Framework Thin Films:From Fundamentals to Applications. Chem. Rev. 2012, 112, 1055−1083.(11) Cohen, S. M. Postsynthetic Methods for the Functionalizationof Metal-Organic Frameworks. Chem. Rev. 2012, 112, 970−1000.(12) Stock, N.; Biswas, S. Synthesis of Metal-Organic Frameworks(MOFs): Routes to Various MOF Topologies, Morphologies, andComposites. Chem. Rev. 2012, 112, 933−969.(13) Murray, L. J.; Dinca, M.; Long, J. R. Hydrogen storage inmetal−organic frameworks. Chem. Soc. Rev. 2009, 38, 1294−1314.(14) Li, J.; Sculley, J.; Zhou, H. Metal-Organic Frameworks forSeparations. Chem. Rev. 2012, 112, 869−932.(15) Ma, L.; Abney, C.; Lin, W. Enantioselective catalysis withhomochiral metal−organic frameworks. Chem. Soc. Rev. 2009, 38,1248−1256.(16) Farha, O. K.; Hupp, J. T. Rational Design, Synthesis,Purification, and Activation of Metal-Organic Framework Materials.Acc. Chem. Res. 2010, 43, 1166−1175.(17) Zhang, Z.; Chen, Y.; Xu, X.; Zhang, J.; Xiang, G.; He, W.; Wang,X. Well-Defined Metal−Organic Framework Hollow Nanocages.Angew. Chem., Int. Ed. 2014, 53, 429−433.(18) Zhang, L.; Wu, H. B.; Lou, X. W. Metal−Organic-Frameworks-Derived General Formation of Hollow Structures with HighComplexity. J. Am. Chem. Soc. 2013, 135, 10664−10672.(19) Hu, H.; Guan, B. Y.; Xia, B. Y.; Lou, X. W. Designed Formationof Co3O4/NiCo2O4 Double-Shelled Nanocages with EnhancedPseudocapacitive and Electrocatalytic Properties. J. Am. Chem. Soc.2015, 137, 5590−5595.(20) Huang, Z. F.; Song, J. J.; Li, K.; Tahir, M.; Wang, Y. T.; Pan, L.;Wang, L.; Zhang, X. W.; Zou, J. J. J. Hollow Cobalt-Based BimetallicSulfide Polyhedra for Efficient All-pH Value Electrochemical andPhotocatalytic Hydrogen Evolution. J. Am. Chem. Soc. 2016, 138,1359−1365.(21) Lee, H.; Dellatore, S. M.; Miller, W. M.; Messersmith, P. B.Mussel-Inspired Surface Chemistry for Multifunctional Coatings.Science 2007, 318, 426−430.(22) Quideau, S.; Deffieux, D.; Douat-Casassus, C.; Pouysegu, L.Plant Polyphenols: Chemical Properties, Biological Activities, andSynthesis. Angew. Chem., Int. Ed. 2011, 50, 586−621.(23) Del Rio, D.; Rodriguez-Mateos, A.; Spencer, J. P. E.; Tognolini,M.; Borges, G.; Crozier, A. Dietary (Poly)phenolics in Human Health:Structures, Bioavailability, and Evidence of Protective Effects AgainstChronic Diseases. Antioxid. Redox Signaling 2013, 18, 1818−1892.(24) Kozlovskaya, V.; Kharlampieva, E.; Drachuk, I.; Cheng, D.;Tsukruk, V. V. Responsive microcapsule reactors based on hydrogen-bonded tannic acid layer-by-layer assemblies. Soft Matter 2010, 6,3596−3608.(25) Sileika, T. S.; Barrett, D. G.; Zhang, R.; Lau, K. H. A.;Messersmith, P. B. Colorless Multifunctional Coatings Inspired by

ACS Applied Materials & Interfaces Research Article

DOI: 10.1021/acsami.7b01788ACS Appl. Mater. Interfaces 2017, 9, 14258−14264

14263

Polyphenols Found in Tea, Chocolate, and Wine. Angew. Chem., Int.Ed. 2013, 52, 10766−10770.(26) Hu, M.; Ju, Y.; Liang, K.; Suma, T.; Cui, J.; Caruso, F. VoidEngineering in Metal−Organic Frameworks via Synergistic Etchingand Surface Functionalization. Adv. Funct. Mater. 2016, 26, 5827−5834.(27) Guo, J.; Ping, Y.; Ejima, H.; Alt, K.; Meissner, M.; Richardson, J.J.; Yan, Y.; Peter, K.; von Elverfeldt, D.; Hagemeyer, C. E.; Caruso, F.Engineering Multifunctional Capsules through the Assembly of Metal-Phenolic Networks. Angew. Chem., Int. Ed. 2014, 53, 5546−5551.(28) Bothma, J. P.; de Boor, J.; Divakar, U.; Schwenn, P. E.;Meredith, P. Device-Quality Electrically Conducting Melanin ThinFilms. Adv. Mater. 2008, 20, 3539−3542.(29) Zhou, J.; Wang, P.; Wang, C.; Goh, Y. T.; Fang, Z.;Messersmith, P. B.; Duan, H. Versatile Core−Shell Nanoparticle@Metal−Organic Framework Nanohybrids: Exploiting Mussel-InspiredPolydopamine for Tailored Structural Integration. ACS Nano 2015, 9,6951−6960.(30) Zhou, J.; Xiong, Q.; Ma, J.; Ren, J.; Messersmith, P. B.; Chen, P.;Duan, H. Polydopamine-Enabled Approach toward Tailored Plas-monic Nanogapped Nanoparticles: From Nanogap Engineering toMultifunctionality. ACS Nano 2016, 10, 11066−11075.(31) Bentley, W. E.; Payne, G. F. Nature’s Other Self-Assemblers.Science 2013, 341, 136−137.(32) Cravillon, J.; Nayuk, R.; Springer, S.; Feldhoff, A.; Huber, K.;Wiebcke, M. Controlling Zeolitic Imidazolate Framework Nano- andMicrocrystal Formation: Insight into Crystal Growth by Time-Resolved In Situ Static Light Scattering. Chem. Mater. 2011, 23,2130−2141.(33) Rahim, M. A.; Kempe, K.; Mullner, M.; Ejima, H.; Ju, Y.; vanKoeverden, M. P. K.; Suma, T.; Braunger, J. A.; Leeming, M. G.;Abrahams, B. F.; Caruso, F. Surface-Confined Amorphous Films fromMetal-Coordinated Simple Phenolic Ligands. Chem. Mater. 2015, 27,5825−5832.(34) Lavenus, S.; Ricquier, J.; Louarn, G.; Layrolle, P. Cell interactionwith nanopatterned surface of implants. Nanomedicine 2010, 5, 937−947.(35) Hu, M.; Belik, A. A.; Imura, M.; Yamauchi, Y. Tailored Design ofMultiple Nanoarchitectures in Metal-Cyanide Hybrid CoordinationPolymers. J. Am. Chem. Soc. 2013, 135, 384−391.(36) Yu, X. Y.; Feng, Y.; Jeon, Y.; Guan, B. Y.; Lou, X. W.; Paik, U.Formation of Ni−Co−MoS2 Nanoboxes with Enhanced Electro-catalytic Activity for Hydrogen Evolution. Adv. Mater. 2016, 28, 9006−9011.(37) Zhang, J. T.; Hu, H.; Li, Z.; Lou, X. W. Double-ShelledNanocages with Cobalt Hydroxide Inner Shell and Layered DoubleHydroxides Outer Shell as High-Efficiency Polysulfide Mediator forLithium−Sulfur Batteries. Angew. Chem., Int. Ed. 2016, 55, 3982−3986.(38) Horcajada, P.; Chalati, T.; Serre, C.; Gillet, B.; Sebrie, C.; Baati,T.; Eubank, J. F.; Heurtaux, D.; Clayette, P.; Kreuz, C.; Chang, J.;Hwang, Y.; Marsaud, V.; Bories, P.; Cynober, L.; Gil, S.; Ferey, G.;Couvreur, P.; Gref, R. Porous metal−organic-framework nanoscalecarriers as a potential platform for drug delivery and imaging. Nat.Mater. 2010, 9, 172−178.(39) Zhuang, J.; Kuo, C.; Chou, L.; Liu, D.; Weerapana, E.; Tsung, C.Optimized Metal-Organic-Framework Nanospheres for Drug Delivery:Evaluation of Small-Molecule Encapsulation. ACS Nano 2014, 8,2812−2819.(40) Ping, Y.; Guo, J.; Ejima, H.; Chen, X.; Richardson, J. J.; Sun, H.;Caruso, F. pH-Responsive Capsules Engineered from Metal-PhenolicNetworks for Anticancer Drug Delivery. Small 2015, 11, 2032−2036.(41) Tang, J.; Salunkhe, R. R.; Liu, J.; Torad, N. L.; Imura, M.;Furukawa, S.; Yamauchi, Y. Thermal Conversion of Core−ShellMetal−Organic Frameworks: A New Method for Selectively Function-alized Nanoporous Hybrid Carbon. J. Am. Chem. Soc. 2015, 137,1572−1580.(42) Yang, S. J.; Antonietti, M.; Fechler, N. Self-Assembly of MetalPhenolic Mesocrystals and Morphosynthetic Transformation toward

Hierarchically Porous Carbons. J. Am. Chem. Soc. 2015, 137, 8269−8273.(43) Liu, R.; Mahurin, S. M.; Li, C.; Unocic, R. R.; Idrobo, J. C.; Gao,H.; Pennycook, S. J.; Dai, S. Dopamine as a Carbon Source: TheControlled Synthesis of Hollow Carbon Spheres and Yolk-StructuredCarbon Nanocomposites. Angew. Chem., Int. Ed. 2011, 50, 6799−602.

ACS Applied Materials & Interfaces Research Article

DOI: 10.1021/acsami.7b01788ACS Appl. Mater. Interfaces 2017, 9, 14258−14264

14264