L-cysteine and poly-L-arginine grafted carboxymethyl cellulose/Ag-In-S quantum dot fluorescent nanohybrids for in vitro bioimaging of brain cancer cells

Although noticeable scientific and technological progress, cancer remains one of the deadliest diseases worldwide and advancements in diagnosis, targeting and treating cancer cells are an urgency. In this study, we designed and synthesized novel amino acid and polypeptide modified polysaccharide derivatives associated with fluorescent nanomaterials for producing nanohybrids with functionalities for bioimaging and cell penetrating. Carboxymethylcellulose (CMCel) was chemically biofunctionalized with L-cysteine (CMCelCys) or poly-L-arginine (CMCelPolyArg) and the conjugates were used as capping ligands for synthesizing fluorescent AgInS2 quantum dots (AIS-QDs) in aqueous colloidal media. These systems were characterized by FTIR, NMR, UV-Vis, TEM-EDX, DLS, zeta potential and PL for assessing physicochemical properties, structural and morphological features. Mitochondrial activity assay (MTT) was used for evaluating preliminary cytotoxicity and confocal laser microscopy for investigating cellular uptake of the nanohybrids. Results confirmed the biofunctionalization of CMCel through amide bonds formation and indicated the formation of water-dispersed fluorescent nanocolloids with core-shell nanostructures composed by semiconductor cores stabilized by shell layers of CMCelCys or CMCelPolyArg. The nanohybrids' optical properties were affected by the grafting of functionalities into CMCel. All nanohybrids demonstrated no in vitro cytotoxicity based on MTT results and were successfully internalized by glioma cells, behaving as fluorescent nanoprobes for bioimaging and biolabeling.