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

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, (SBET = 662 m2/g) and total pore volume (VT = 1.33 cm3/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. [Display omitted] •New attempts on estimating adsorption energy distribution (AED) were reported.•New approach based on statistical mechanics was developed to understand protein adsorption.•Adsorption isotherms of protein onto resin and its carbon nanoparticles with two steps were found.•The statistical physics approach supports the adsorption behavior in each step.