Nanofibrous Texturizing for Prevention of Bacterial Infection on Biomedical Implants

Hannah Barber

Hannah Barber1,4, Mehdi Kargar2, John Haught2, Amrinder Nain, Ph.D. 2,3, and Bahareh Behkam, Ph.D.

2,3

Biological Sciences Department1, Mechanical Engineering Department2, School of Biomedical Engineering and Sciences3,

Scieneering Program4 Virginia Tech, Blacksburg VA

BMES Annual Meeting 2011

10/15/2011

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Introduction- The Biofilm Problem

A biofilm developing around the eyehole of a latex catheter. The catheter had been removed from a patient 5 days after insertion.

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Hannah Barber, MicroN BASE 10/15/11

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Motivation- Catalyst for a Solution• Current treatment for biofilm-associated infections:

▫Surgical replacement of the implant; ▫Long-term antibiotic therapy.

• We need NEW treatments because:▫Current treatments are expensive;▫They compound the antibiotic-resistance problem.

Hannah Barber, MicroN BASE 10/15/11

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Hannah Barber, MicroN BASE 10/15/11

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Inspiration- Taking a Queue from Nature A:The naturally antifouling surface of M. edulis; B: the sub-micron topography of the priostracum of M. edulis.

A B

C DC: The Galapagos shark; D: the micro-topography features of the shark’s skin. Im

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Image courtesy of FlickRiver.com

Bers, A. V. and Wahl, M., Biofouling, 2004. 20(1): 43-51.

Hannah Barber, MicroN BASE 10/15/11

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Objective- Aspiration for a Design•To investigate and characterize the

antifouling properties of varying nanofibrous surface topographies.

Hannah Barber, MicroN BASE 10/15/11

•We used polystyrene (PS) fibers with diameter 500 nm, spaced 2000 nm apart on PS substrates.

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STEP Fiber Manufacturing*

Pseudo-dry spinning method, STEP, manufacturing platform used for fabrication of nanofibrous surfaces.

200 µm

200 µm

Hannah Barber, MicroN BASE 10/15/11

*Nain, A. S., et al. Macromolecular Rapid Communications,  2009. 30(16) : 1406-1412.

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Bacterial Assay

•Experimental parameters:▫ Model organism is

Pseudomonas aeruginosa (PAO1 strain)

▫ Culture is presented to samples at OD600 = 0.65

▫ Incubated at 37°C▫ Incubated for 16 hours

Retention assay with suspended sample substrate.

Hannah Barber, MicroN BASE 10/15/11

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Imaging- Illuminating the Databare single-layer double-layer

ImageJ was used to quantify:

1.Areal density of attached bacteria

2.Areal density of bacterial colonies

3.Cluster size

Hannah Barber, MicroN BASE 10/15/11

5 μm

5 μm 5 μm

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Results- Understanding the Information

• Change in number of clusters:▫ 17% decrease from bare to

single and to double

• Change in bacteria per cluster:▫ 21% decrease from bare to

single▫ 24% decrease from bare to

double

• Change in bacterial attachment:▫ 59% decrease from bare to

single▫ 62% decrease from bare to

double

Hannah Barber, MicroN BASE 10/15/11

bare single double0

1

2

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9Bacterial Cluster Formation

number of clusters

bacteria per cluster

bare single double0

0.005

0.01

0.015

0.02

0.025

0.03

0.035

Bacterial Attachment

are

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sity

(b

acte

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m2)

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Conclusions and Future Work• We can conclude that both the single-

layer and double-layer topographies are capable of decreasing both bacterial attachment and cluster formation.

• In the future, our team will study the effects of surface topography on gene expression in pathogenic bacteria.

Hannah Barber, MicroN BASE 10/15/11