New insights in the adsorption of Bovine Serum Albumin onto carbon nanoparticles derived from organic resin: Experimental and theoretical studies

Abstract Organic resin and its derived carbon nanoparticles (CNPs) were prepared and used to adsorb Bovine Serum Albumin (BSA). Characterization by Boehm titrations and X-ray photoelectron spectroscopy showed that resin has the largest densities of oxygen groups with a higher O/C atomic ratio (0.381) compared to CNPs (0.059). Field Emission Scanning Electron Microscopy indicated a spherical shape for both adsorbents with a mean diameter of about 50 nm and 100 nm for CNPs and resin, respectively. The nitrogen adsorption-desorption isotherms showed that CNPs present a high specific surface area, (S BET  = 662 m 2 /g) and total pore volume (V T  = 1.33 cm 3 /g) compared to the resin. A stepwise shape was observed in the adsorption isotherms indicating two different processes. At low concentration, the resin presented a higher adsorbed uptake (0.38 mg/mg) compared to CNPs (0.21 mg/mg) due to its higher amount of oxygen groups. At high concentration, the adsorbed quantity for CNPs (1.30 mg/mg) was higher than the one for the resin (0.97 mg/mg) which is probably due to the porosity effect. To better understand this adsorption behavior, a new approach based on statistical physics was developed. This theoretical model led us to evaluate the adsorption energy distribution and to confirm the two steps adsorption phenomenon.