Synthesis, morphostructure, surface chemistry and preclinical studies of nanoporous rice husk-derived biochars for gastrointestinal detoxification

This article summarizes the methodology of synthesis, surface functionalization and structural properties of rice husk-derived nanostructured carbon enterosorbents (biochars) in connection with the preliminary in vitro study results of uraemic toxin adsorption in model experiments, as well as preclinical trials in vivo. The obtained nanostructured carbon sorbents were studied using a number of modern physicochemical methods of investigation: low-temperature nitrogen adsorption, isotherms recording and calculation of the specific surface area, pore volumes were carried out using the Autosorb-1 "Quantachrome" device. Scanning electron microscopy and EDS-analysis. Mercury intrusion porosimetry analysis of the ACs were accomplished using "Quantachrome Poremaster" data analysis software. In vitro adsorption results assessed by use of HPLC and UV-spectroscopy for the nanostructured carbon sorbents with respect to the investigated low-molecule toxins suggest that the rice husks-derived carbon enterosorbents modified with the functional groups are able to reduce clinically significant levels of uraemic toxins and are comparable to the commercial enterosorbents. Based on the results of the comparative analysis for biocompatibility of canine kidney epithelial cells it was determined that the samples of the modified sorbents CRH-P-450 and CRH-475-KOH-850-N do not exhibit cytotoxicity in comparison with the commercial carbon enterosorbent «Adsorbix Extra». According to the results of the in vivo studies, it was determined that there was a positive effect of the enterosorbent CRH-P-450 on uremia and intoxication.