Sustainable Biorefinery Strategy for Synthesis of Nanostructured Materials from Fish Waste and Assessment of Their Cytocompatibility on Colon Cells

Fish waste is commonly thrown away as discarded garbage from the fish processing sector, contributing to environmental pollution and resource depletion. Due to its variable decay rate and pungent odor, fish waste poses an ecological threat. Thus, effective management strategies are required to minimize its impact. In this present study, we have utilized the Nemipterus japonicus fish scale as a sustainable and greener precursor to synthesizing carbon quantum dots (C-QDs) and hydroxyapatite nanostructures (HA-Ns) through a biorefinery strategy. The prepared C-QDs and HA-Ns crystalline phase and structural properties were studied using X-ray diffractometer and transmission electron microscopy, respectively. TEM observations clearly indicate that C-QDs possessed a spherical size of 10–35 nm. Also, HA-Ns have irregular morphological features with a 45–60 nm diameter. The impact of fish waste-derived C-QDs and HA-Ns on colon cells was assessed using in vitro assays. According to the cell viability results, around 18% and 14% of cell death were found in 400 µg/mL of C-QDs and HA-Ns exposure, respectively. Interestingly, these nanostructures do not cause cellular and nuclear morphological changes in colon cells. Additionally, the mitochondria membrane potential and ROS level were not changed significantly in C-QDs and HA-Ns cells compared to untreated cells. Overall, these study results revealed that C-QDs and HA-Ns are cytocompatible and non-toxic, which can potentially be applied in biomedical or food industry applications.