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Vi Khanh Truong, PhDOctober 7‐10, 2012 • Atlanta, Georgia, USA
Investigation of bacterial attachment patterns on micro‐ and
nano‐ restricted surface topographies
Vi Khanh Truong, PhDOctober 7‐10, 2012 • Atlanta, Georgia, USA
Outline of presentation• Overview• Aims• Outcomes
Bacterial attachment behaviours on ultrafine grained titaniumBacterial attachment behaviours on subnano‐ and nano‐scale
topographyBacterial attachment behaviour on self‐cleaning surfacesImprovement of anti‐biofouling properties
• Conclusion• Practical outcomes
Vi Khanh Truong, PhDOctober 7‐10, 2012 • Atlanta, Georgia, USA
Utilisation of titanium in biomedical industry• Benefits:
Biocompatible – non‐toxic
Light
Strong
Corrosion resistant
• Medical applications:
Dental implants
Orthopaedic implants
Surgical instruments
Vi Khanh Truong, PhDOctober 7‐10, 2012 • Atlanta, Georgia, USA
Infections associated with implants
Staphylococcus aureus (34%)
1 µm diameter; non‐motile; cell surface adhesin proteins, other EPS
Pseudomonas aeruginosa (8%)
0.5‐0.8 µm x 1.5‐3.0 µm; flagellum; fimbriae, polysaccharide capsule, EPS Frequency of main pathogenic species among
orthopaedic clinical isolates of implant‐associated infections (Campocia, 2006)
Vi Khanh Truong, PhDOctober 7‐10, 2012 • Atlanta, Georgia, USA
Theoretical model of biofilm formation
Biofilm formation model (Greenberg, 2002)
Factors influencing biofilm formation on non‐biological surfaces
• Surface charges
• Hydrophobicity: thermodynamic approach, DLVO or extended DLVO theories.
• Surface topography
Vi Khanh Truong, PhDOctober 7‐10, 2012 • Atlanta, Georgia, USA
Aims of the research• Fabricate and investigate surfaces with topographic features ranging from
micro‐scale to sub‐nanometric‐scale
• Conduct systematic and comprehensive studies to investigate the impact of micro‐/nano‐topography on of bacterial attachment
• Explicate bacterial attachment response to changes of the surface topography
• Development of anti‐biofouling coatings for titanium surfaces
Vi Khanh Truong, PhDOctober 7‐10, 2012 • Atlanta, Georgia, USA
Production of ultrafine‐grained titaniumPressure
Punch
SleeveHeater
Shaping insert
Preform
Stopper plate
ECAPAs‐received
Following with mechanical polishing and the combination of chemical and mechanical polishing
Vi Khanh Truong, PhDOctober 7‐10, 2012 • Atlanta, Georgia, USA
Bacterial attachment on ultrafine‐grained titanium
As-r
ecei
ved
Ti
EC
AP
Ti
SEM
1 µm4 µm
10 µm
1 µm4 µm
10 µm 10 µm
10 µm
AFM CLSM
P. aerug
inosa
S. aureus
S: S. aureusP: P. aeruginosa
Mechanical polishingChemico‐mechanical polishing
How does surface topography modulate bacterial attachment?
Vi Khanh Truong, PhDOctober 7‐10, 2012 • Atlanta, Georgia, USA
Fabrication of Ti thin films
To control Ti thin film thicknesses at atomic scale, withaverage roughness
ranging from1.2 nm—0.2 nm
Vi Khanh Truong, PhDOctober 7‐10, 2012 • Atlanta, Georgia, USA
Surface topography
Ra = 1.22 ± 0.27 nm
Rq = 1.61 ± 0.34 nm
Ra = 0.92 ± 0.06 nm
Rq = 1.16 ± 0.06 nm
Ra = 0.58 ± 0.08 nm
Rq = 0.73 ± 0.14 nm
Vi Khanh Truong, PhDOctober 7‐10, 2012 • Atlanta, Georgia, USA
Attachment of bacteria on Ti thin films P. aeruginosa S. aureus
Red: bacterial cells; Green: exopolysaccharide produced by bacteria
Ra (nm)
0.0 0.2 0.4 0.6 0.8 1.0 1.2
Per
cent
age
of a
ttche
d ce
lls (%
)
0
2
4
6
8
10
S. aureus
P. aeruginosa
Vi Khanh Truong, PhDOctober 7‐10, 2012 • Atlanta, Georgia, USA
P. aeruginosa and S. aureus on the surfaces with nano‐topographic features
Vi Khanh Truong, PhDOctober 7‐10, 2012 • Atlanta, Georgia, USA
Fabrication of hierarchical structures on titanium surfaces
Schematic of femtosecond laser ablation setup (Courtesy of Elena Fadeeva, Hannover Laser Zentrum)
10 pulses 20 pulses
Ripple effect
Vi Khanh Truong, PhDOctober 7‐10, 2012 • Atlanta, Georgia, USA
Surface topography and self‐cleaning effectAs‐received Structured
Vi Khanh Truong, PhDOctober 7‐10, 2012 • Atlanta, Georgia, USA
Attachment of bacteria on lotus‐like Ti surfaces
As‐received Ti Structured Ti As‐received Ti Structured TiP. aeruginosa S. aureus
Low attachment of P. aeruginosa on structured Ti Induced attachment of S. aureus on
structured Ti
Vi Khanh Truong, PhDOctober 7‐10, 2012 • Atlanta, Georgia, USA
Localisation of spherical S. aureuson nano‐restricted surface topography
Attachment behaviour of S. aureus and P. aeruginosa on micro‐/nano‐topography
Increased surface area favourable for the attachment of spherical S. aureus, not of rod‐shaped P. aeruginosa
Vi Khanh Truong, PhDOctober 7‐10, 2012 • Atlanta, Georgia, USA
Improving anti‐biofouling properties for titanium surfaces
Plasma‐enhanced chemical vapour deposition system
Terpinen‐4‐ol
Vi Khanh Truong, PhDOctober 7‐10, 2012 • Atlanta, Georgia, USA
Performance of polyterpenol coatings on titanium surfaces
Green: viableRed: dead
Vi Khanh Truong, PhDOctober 7‐10, 2012 • Atlanta, Georgia, USA
ConclusionSurface topography with dimensions ranging from micro‐ to subnano‐features may control the extent of bacterial attachment
The extent of bacterial attachment on hierarchic structures of superhydrophobic surfaces is variable and dependant on the bacterial morphology
Bacterial attachment on the subnano‐/nano‐smooth surfaces cannot be explained by previously known mechanisms, e.g. flagella, fimbriae, production of EPS, which are believed facilitating the bacterial attachment
Vi Khanh Truong, PhDOctober 7‐10, 2012 • Atlanta, Georgia, USA
Practical outcomesImprovement of anti‐biofouling properties achieved using polymerised terpinen‐4‐ol, main constitute of antibacterial tea tree oil
Understanding the relationship between bacterial attachment and surface roughness assisting in the design of biomaterials with minimum risk of bacterial infections
To optimize the process of osseointegration on modified titanium surfaces, investigation of competitive colonization between eukaryotic and prokaryotic cells required in the future direction
Vi Khanh Truong, PhDOctober 7‐10, 2012 • Atlanta, Georgia, USA
Acknowledgements
My supervisorsProf. Elena IvanovaDr. Francois MalherbeProf. Russell CrawfordProf. Christopher Berndt
Faculty of Life and Social SciencesDr. Hayden WebbMr. Jafar Hasan
Faculty of Engineering and Industrial SciencesDr. James Wang
Centre for MicrophotonicsProf. Saulius JuodkazisMr. Gediminas Gervinskas
Prof. Robert LambDr. Alex Wu
Dr. Mark TobinDr. Ljiljana Puskar
Dr. Manoj SridharMr. Douglas Mair
Prof. Yuri EstrinDr. Rimma Lapovok
Prof. Boris ChichkovMs. Elena Fadeeva
A/Prof. Jacob MohanDr. Katia Bazaka
Vi Khanh Truong, PhDOctober 7‐10, 2012 • Atlanta, Georgia, USA
References• VK Truong, HK Webb, E Fadeeva, BN Chichkov, AHF Wu, R Lamb, RJ Crawford, J Wang, EP Ivanova (2012)
Biofouling, 28:539:550.• RJ Crawford, HK Webb, VK Truong, J Hasan, EP Ivanova (2012) Advances in Colloids and Interface Science,
179‐182:142‐149.• HK Webb, VK Truong, J Hasan, C Fluke, RJ Crawford, EP Ivanova (2012) Scanning, in press.• EP Ivanova, VK Truong, HK Webb, VA Baulin, JY Wang, N Mohammodi, F Wang, C Fluke, RJ Crawford (2011)
Scientific Reports (Nature Publishers), • HK Webb, J Hasan, VK Truong, RJ Crawford, EP Ivanova (2011) Current Medicinal Chemistry, 18:3367‐3375.• K Bazaka, MV Jacob, VK Truong, RJ Crawford, EP Ivanova (2011) Polymers, 3:388‐404. • E Fadeeva, VK Truong, M Stiesch, BN Chichkov, RJ Crawford, J Wang, EP Ivanova. (2011) Langmuir,
27:3012‐3019.• Y Estrin, EP Ivanova, A Michalska, VK Truong, R Lapovok, R Boyd. (2011) Acta Biomaterialia, 7:900‐906.• K Bazaka, MV Jacob, VK Truong, F Wang, WAA Pushpamali, JY Wang, AV Ellis, CC Berndt, RJ Crawford, EP
Ivanova. (2010) Biomacromolecules, 11:2016‐2026.• VK Truong, R Lapovok, Y Estrin, S Rundell, JY Wang, D Barnes, C Fluke, RJ Crawford, EP Ivanova (2010)
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