Abstract:
Controlling bacterial growth using artificial nanostructures inspired from natural species is of immense importance
in biomedical applications. In the present work, a low cost, fast
processing, and scalable anisotropic wet etching technique is
developed to fabricate the densely packed disordered silicon
nanopyramids (SiNPs) with nanosized sharp tips. The bactericidal
characteristics of SiNPs are assessed against strains implicated in
nosocomial and biomaterial-related infections. Compared to the
bare silicon with no antibacterial activities, SiNPs of 1.85 ± 0.28 μm height show 55 and 75% inhibition of Escherichia coli (Gramnegative) and Bacillus subtilis (Gram-positive) bacteria, whereas the silicon nanowires (SiNWs) fabricated using a metal-assisted
chemical etching method show 50 and 58% inhibition of E. coli and B. subtilis. The mechanistic studies using a scanning electron
microscope and live/dead bacterial cell assay reveal cell rupture and predominance of dead cells on contact with SiNPs and SiNWs,
which confirms their bactericidal effects. Chemical stability and cell viability studies demonstrate the biocompatible nature of SiNP
and SiNW surfaces. Owing to their capability to kill both Gram-negative and positive bacteria and minimal toxicity to murine
fibroblast cells, SiNPs can be used as an antibacterial coating on medical devices to prevent nosocomial and biomaterial-related
infections.
