Facile synthesis of highly fluorescent nitrogen-doped carbon quantum dots and their role in bioimaging of some pathogenic microorganisms

Carbon quantum dots (CQDs) with outstanding fluorescence properties have shown enormous applications in bioimaging due to their biocompatibility and nano size attribute. However, the toxicity of QDs may hinder their implementation in biomedical use. Here, nitrogen-doped carbon quantum dots (N-CQDs) were produced by employing a microwave-assisted approach and then their in vivo and in vitro toxicity has been investigated. An in vitro toxicity study was conducted against human breast adenocarcinoma cell lines (MDA-MB-361) by considering the concentration of 0–600μg mL−1 of the N-CQDs and the in vivo toxicity examination was done in Swiss albino mice for 30 days by considering two concentrations of N-CQDs, i.e., 10mg/kg BW (body weight) and 20mg/kg BW. Several parameters have been inspected by these studies like cell viability, antioxidant enzymes studies, and hematological and histopathological studies, and concluded that the synthesized NCQDs are non-toxic and can be used safely for bioimaging. Furthermore, the luminescence properties of N-CQDs were inquired by labeling them on a variety of fungal and bacterial cells. When the N-CQD-labeled cells were excited at two wavelengths, it leads to the emission of green and red fluorescence enabling them ideal for bioimaging. Briefly, there is a production of inexpensive and biocompatible N-CQDs of an average particle size of ~3.16 nm that can serve as universal fluorescent agents for the detection of diverse groups of pathogenic microorganisms.