Radical copolymerization of acrylamide (Am) (90 mol%) with N-acryloyl-m-aminophenylboronic acid (NAAPBA) (10 mol%) carried out on the surface of glass slides in aqueous solution and in the absence of chemical cross-linkers, resulted in the formation of thin semitransparent gels. The phenylboronic acid (PBA) ligand density was ca. 160 micromol/ml gel. The gels exhibited a macroporous structure and displayed optical response to sucrose, lactose, glucose and fructose in 50 mM sodium phosphate buffer, in the pH range from 6.5 to 7.5. The response was fairly reversible and linearly depended on glucose concentration in the wide concentration range from 1 to 60 mM at pH 7.3. The character of response was explained by the balance of two competing equilibrium processes: binding of glucose to phenylboronate anions and binary hydrophobic interactions of neutral PBA groups. The apparent diffusion coefficient of glucose in the gels was ca. 2.5 x 10(-7) cm(2)/s. A freshly prepared gel can be used daily for at least 1 month without changes in sensitivity. Autoclaving (121 degrees C, 1.2 bar, 10 min) allows for the gels sterilization, which is important for their use as glucose sensors in fermentation processes.
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.
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