Carbon quantum dots derived from agro waste biomass for pioneering bioanalysis and in vivo bioimaging

Waste to Wealth's mission aims to develop valuable products for choice of environmental and biological purposes, especially from agricultural wastes. A vast variety of organic and inorganic elements that are left over from agricultural activities like crop cultivation or livestock raising are referred to as agricultural waste, for example, pista shell (PS) and groundnut shell (GNS). These agricultural waste materials can be effectively utilized for preparing wealth materials depending on materials and their composition. Owing to the presence of high carbon content in these waste materials, preparing carbon-based nanostructured wealth materials for environmental and biological applications is significant, interestingly, it also fulfills the sustainable approach along with a cost-effective strategy. This hypothesis led us to prepare one such type of carbon-based nanostructured material, carbon quantum dots (CQDs), from PS and GNS agro-wastes. These agro-wastes derived CQDs were formulated by hydrothermal method and their distinct structural, morphological, functional, optical, and bioactive properties were determined. The XRD data divulges the amorphous nature of CQDs with interlayer spacing (similar to 0.30 nm) similar to graphite. HRTEM images express spherical morphology with a particle size of ca. 5 nm and ca. 12 nm for PSE and GNSE CQDs, respectively. Raman spectra divulge a doublet D band (1335 and 1447 cm(-1)) with I-D/I-G ratio of 1.6 and 1.2 for PSE and GNS CQDs, respectively. Using UV-Vis and photoluminescence (PL) spectroscopy data reveals that PSE and GNS CQDs show excitation at 370 and 309 nm, and emission at 456 and 440 nm, respectively. Further, high fluorescence quantum yield (9.5 % for PSE and 9.0 % for GNS), virtuous cell viability (90 % for both CQDs), high hemocompatibility (0.3 for PSE and 0.1 % for GNS), accelerated anti-bacterial activity, protein denaturation, bacteria interaction, and growth factors (IGF-1, Col-1) expression levels enable these CQDs to function as a probe for live quantitative bioimaging in Zebrafish.