Comparative study of the characteristics and fluorescent properties of three different biochar derived‑carbonaceous nanomaterials for bioimaging and heavy metal ions sensing

Abstract Three types of biochar (microalgae, rice straw and sorghum straw) from biomass thermal conversion production were tested for producing biochar-derived carbonaceous nanomaterials (BCN). BCN were obtained after using chemical depolymerisation and solvent extraction, NanoRefinery process. Microalgae biochar-derived carbonaceous nanomaterials (MAB-CN), rice straw biochar-derived carbonaceous nanomaterials (RSB-CN) and sorghum straw biochar-derived carbonaceous nanomaterials (SSB-CN) were characterised using spectroscopic and microscopic techniques. This characterisation evidenced significant differences among the three BCN with MAB-CN exhibiting greater structural differences compared to RSB-CN and SSB-CN. Biocompatibility, cellular uptake, and cellular localisation were evaluated using three yeast species, Saccharomyces cerevisiae, Candida albicans, and Yarrowia lipolytica. While all BCN were biocompatible, the degree of biocompatibility for each species was dependent on pH, BCN concentration and BCN type. Additionally, BCN were evaluated as transducers for the detection of 12 heavy metal ions. MAB-CN, RSB-CN, and SSB-CN had different responses to the 12 heavy metal ions. The SSB-CN/Cu (II) and the MAB-CN/Zn (II) combinations evidenced selectivity over the other metal ions with these combinations having limits of detection of 0.0125 μM and 9 μM, respectively. The results from this research pave the way for BCN novel applications for bioimaging and heavy metal ions sensing probes.