Investigation of physicochemical and biological properties of boron-doped biochar

Boron doping of biochar leads to the formation of activated oxygen species and pores and defects in the carbon structure Therefore, boron-containing biochar was prepared by treating boric acid (H3BO3) solutions in different concentrations of hazelnut shells before pyrolysis. DSC results showed that treatment of biomass with solutions containing a low concentration (0.1 wt. %) of H3BO3 increased the degradation of cellulose and hemicellulose, but also increased char formation. However, treatment with solutions containing 2% and 5% H3BO3 increased biochar oxidation with the formation of boron oxide (B2O3). The FT-IR and XPS results showed the presence of B-B, B-O, and B-O-B in the H3BO3 treatment, which is due to the formation of B2O3. The examination of the proliferation of L929 mouse fibroblast cells in response to different concentrations of boron-containing biochars using the MTT assay revealed that biochar treated with 2% H3BO3 promoted cell growth (100.32 +/- 1.93). However, above this concentration, the formation of polycrystalline B2O3 species exhibited an inhibitory effect on cell proliferation (81.98 +/- 1.26) in the samples of H3BO3-doped biochar with 5% concentration. The results of the in vitro hemolysis tests for undoped biochar and high boron-containing (% 5) biochar sample showed mild hemolytic activity, with percentages of 2.46 +/- 0.02 and 3.08 +/- 0.04, respectively, according to the reported standards. Antimicrobial studies have shown that Candida albicans (a yeast, ATCC 10231) is more sensitive to H3BO3 than Staphylococcus aureus (Gram-positive bacteria, ATCC 29213). Boron-containing biochar can be used in a variety of applications, including biosensing, drug delivery, biological scaffolds, and biological imaging, as well as an adsorbent in the removal of pollutants and a catalyst in oxidation and electrochemical reactions.