Polyvinylpyrrolidone wrapped single walled carbon nanotubes: solid state characterization and superior antimicrobial activity / Mazzura Wan Chik

Single walled carbon nanotubes (SWNTs) are special in a way that they perform varies physical and chemical characteristics with diverse applications in many fields of scientific research. Despite their outstanding characteristics, SWNTs is challenged by its poor aqueous solubility property due to its super hydrophobicity that becomes a hindrance for their application in many important areas including pharmaceutical life sciences. Previously, the functionalization (f-) and non-covalent functionalization (non-covalent-f) methods have been explored to increase solubility of SWNTs. However, the f- method is said to affect the intrinsic properties of SWNTs while the non-covalent-f by polymer wrapping does not. This study shall elucidate the solid state characterization, the probable antimicrobial and antiphysiologic effects of the synthesized polymer polyvinylpyrrolidone wrapped SWNTs (PVP-SWNTs) on bacterial Escherichia coli (E. coli). First, the characterization of pure SWNTs, PVP and PVP-SWNTs in solid state was determined. These powdered materials were brought to spectral analysis, and thermophysical assay. Results indicated that the solubility of SWNTs in water had increased when aided with PVP wrapping. Results of the spectral analysis revealed that the unprocessed PVP spectra appeared dominantly in the PVP-SWNTs spectral analysis indicating wrapping of PVP over SWNTs. While, the thermophysical study showed formation of endothermic melting peaks of PVP appeared on PVP-SWNTs thermogram which could be interpreted as engagement between PVP and SWNTs. The second part of the study looked at antimicrobial and antiphysiologic activities of dispersed PVP-SWNTs and naked SWNTs on E. coli. The conventional antimicrobial study revealed that at 1 mg/ml PVP-SWNTs were able to inhibit the growth of E. coli and reduced 95 % of optical density (OD) readings. Finally, increased concentration of PVP-SWNTs and SWNTs showed better antiphysiologic activities towards E. coli (maximum concentration is 11.5 v/v % equivalents to 300 μg). The one-way ANOVA showed significant results between groups (p = 0.002).