Protein nanoparticle interaction: A spectrophotometric approach for adsorption kinetics and binding studies

• The strong affinity of BSA for GNPs were confirmed by the high value of binding constant (Ks = 2.2 × 1011 L/mol).
• GNPs are excellent adsorbent for the model protein BSA, the percentage adsorption increased monotonically with time.
• Adsorption of BSA on GNPs surface is directly proportional to pH and BSA concentration and inversely related to temperature.
• Values of ΔH0, ΔG0 and Ea suggested that the adsorption process was spontaneous and governed by chemisorptions interaction.

Investigating the protein nanoparticle interaction is crucial to understand how to control the biological interactions of nanoparticles. In this work, Model protein Bovine serum albumin (BSA) was used to evaluate the process of protein adsorption to the gold nanoparticles (GNPs) surface. The binding of a model protein (BSA) to GNPs was investigated through fluorescence quenching measurements. The strong affinities of BSA for GNPs were confirmed by the high value of binding constant (Ks) which was calculated to be 2.2 × 1011 L/mol. In this consequence, we also investigated the adsorption behavior of BSA on GNPs surface via UV–Vis spectroscopy. The effect of various operational parameters such as pH, contact time, initial BSA concentration, and temperature on adsorption of BSA was investigated using batch adsorption experiments. Kinetics of adsorption was found to follow the pseudo-second order rate equation. The suitability of Freundlich and Langmuir adsorption models to the equilibrium data was investigated. The equilibrium adsorption was well described by the Freundlich isotherm model. The maximum adsorption capacity for BSA adsorbed on GNPs was 58.71 mg/g and equilibrium constant was 0.0058 calculated by the Langmuir model at 298 K and pH = 11.0. Thermodynamic parameters showed that the adsorption of BSA onto GNPs was feasible, spontaneous, and exothermic.

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