Highly luminescent biocompatible doped nano carbon dot composites as efficient antibacterial agents

Abstract

ABSTRACT Highly luminescent nitrogen andsulfur-doped carbon dots were synthesized by a microwave-assisted greener synthetic strategy and the anti-bacterial activity of the carbon dot (C-dots) composites were analyzed. The obtained gel-like C-dots were found to be highly fluorescent in very dilute solutions emitting blue light even in the visible range. The formation of N and S doped C-dots were confirmed from theUV-visible spectral studies, EDS analysis, fluorescence measurements, and the morphology and size of the C-dots were established by High-resolution TEM. The synthesized C-dots were dispersed in three biologically relevant and biocompatible polymeric matrices and the composites of C-dots were fabricated. It was interestingly noticed that the introduction of C-dots in the water-soluble polymeric networks like polyvinyl alcohol (PVA), chitosan, and poly sulfonatestyrene, i.e., the composites of C-dots enhanced the stability and the photoluminescent properties. The morphology of the composites was analyzed using SEM. The antimicrobial studies reveal the potential application of carbon dot composites as an excellent anti-bacterial agent against gram-positive and gram-negative bacteria. The composite having the highest antibacterial activity was checked for the cytotoxicity studies. The results revealed that the C-dot composite has a minimal impact on cell viability and have an IC50value of 118.4 µg/ml. This IC 50 value was highly significant and was very low compared to other C-dots reported in the literature so far. This surely confirmed their low toxicity and excellent biocompatibility for the in vivo and in-vitro studies and will explore the potential application of the composites for targeted drug delivery, development of drug delivery devices, and bioimaging studies.