Antimicrobial Biomaterials Based On Single Walled Carbon Nanotubes and Charged Polymers

Biomedical implant infection represents a significant health care problem. We investigate here the possibility of single walled carbon nanotubes (SWNT), together with aqueous polymers, as antimicrobial thin film biomaterials. To address the SWNT solubility problem, we investigate two methods: i) assembly with the non-toxic surfactant Tween-20 and ii) encapsulation within polysiloxane shells. SWNT in aqueous solution is then combined with linear polyelectrolytes to form thin films via layer-by-layer (LbL) assembly. SWNT solubility and SWNT-polymer film properties are characterized via transmission electron microscopy (TEM), scanning electron microscopy (SEM), zeta potential analysis, optical waveguide lightmode spectroscopy (OWLS), and dissipative quartz crystal microgravimetry (QCMD).  We observe both surfactant and polysiloxane coatings to result in highly soluble single and small bundle SWNT, that readily assemble via LbL with charged polymers to form films of controlled nanoscale thickness and nanotube  content. We find films containing SWNT to be highly antimicrobial and cytocompatible: > 90% of E. coli are inactivated on SWNT containing films (vs. ca. 10% for control films), and MC3T3-E1 osteoblast-like cells exhibit increased attachment and metabolic activity on SWNT containing versus control films.