The document summarizes Hannah Barber's presentation on using nanofibrous texturizing of biomedical implants to prevent bacterial infection. The presentation described how biofilms pose problems for implants, motivated developing new non-antibiotic treatments, and showed how nature inspired using topography to reduce bacterial attachment. Barber's team fabricated polystyrene fibers to mimic skin and tested their ability to reduce Pseudomonas aeruginosa attachment and clustering, finding 59-62% less attachment and 17-24% smaller clusters versus flat surfaces. Future work will analyze topography effects on bacterial gene expression.

1. BMES Annual Meeting 2011
10/15/2011
Hannah Barber
Nanofibrous Texturizing for Prevention of
Bacterial Infection on Biomedical Implants
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

2. 2
Hannah Barber, MicroN BASE 10/15/11
Introduction- The Biofilm Problem
Image courtesy of MedScape.com
A biofilm developing around the eyehole of a latex catheter. The
catheter had been removed from a patient 5 days after insertion.

3. 3
Hannah Barber, MicroN BASE 10/15/11
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.

4. 4
Hannah Barber, MicroN BASE 10/15/11

5. 5
Hannah Barber, MicroN BASE 10/15/11
Inspiration- Taking a Queue from Nature
A B A:The naturally
antifouling
surface of M.
edulis;
B: the sub-
micron
topography of
the priostracum
of M. edulis.
Bers, A. V. and Wahl, M., Biofouling, 2004. 20(1): 43-51.
C: The C D
Image courtesy of medGadget.com
Galapagos
shark;
D: the
micro-
topography
features of
the shark’s
skin. Image courtesy of FlickRiver.com

6. 6
Hannah Barber, MicroN BASE 10/15/11
Objective- Aspiration for a Design
• To investigate and characterize the antifouling
properties of varying nanofibrous surface
topographies.
• We used polystyrene (PS) fibers with diameter
500 nm, spaced 2000 nm apart on PS substrates.

7. 7
Hannah Barber, MicroN BASE 10/15/11
STEP Fiber Manufacturing*
200 µm
Pseudo-dry spinning
200 µm
method, STEP, manufacturing platform used
for fabrication of nanofibrous surfaces. *Nain, A. S., et al. Macromolecular Rapid
Communications, 2009. 30(16) : 1406-1412.

8. 8
Hannah Barber, MicroN BASE 10/15/11
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.

9. 9
Hannah Barber, MicroN BASE 10/15/11
Imaging- Illuminating the Data
bare single-layer double-layer
5 μm 5 μm 5 μm
ImageJ was used to quantify:
1. Areal density of attached
bacteria
2. Areal density of bacterial
colonies
3. Cluster size

10. 10
Hannah Barber, MicroN BASE 10/15/11
Results- Understanding the Information
Bacterial Attachment
0.05
areal density (bacteria/µm2)
0.045
0.04
0.035 • Change in bacterial attachment:
0.03
0.025
▫ 59% decrease from bare to single
0.02
0.015
▫ 62% decrease from bare to double
0.01
0.005
0
bare single double
Bacterial Cluster Formation
• Change in number of clusters: 10
9
▫ 17% decrease from bare to single 8
and to double 7
6 number of
clusters
5
4
• Change in bacteria per cluster: 3
bacteria per
cluster
▫ 21% decrease from bare to single 2
1
▫ 24% decrease from bare to double 0
bare single double

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Hannah Barber, MicroN BASE 10/15/11
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.