Absolute reaction rate and kinetics of protein adsorption at solid-liquid interfaces

Area of Science:

• Surface chemistry
• Physical chemistry
• Biomaterials science

Background:

• Protein adsorption is crucial in biomaterial applications and biological interactions.
• Understanding the kinetics and thermodynamics of protein adsorption provides insights into surface-protein interactions.

Purpose of the Study:

• To investigate the adsorption kinetics of bovine serum albumin (BSA) on alumina, silica, carbon, and chromium powders.
• To elucidate the thermodynamic mechanisms governing BSA adsorption under varying conditions.
• To explore the influence of external factors like pH, ionic strength, temperature, and additives on adsorption.

Main Methods:

• Kinetic studies of BSA adsorption over time.
• Analysis using first-order rate equations to determine rate constants (Ka1, Ka2).
• Thermodynamic analysis using Arrhenius and Eyring equations to calculate activation parameters (Ea, ΔH*, ΔS*, ΔG*).
• Investigation of the effects of SDS, CTAB, and neutral salts.

Main Results:

• BSA adsorption rates consistently fit a first-order kinetic model with two distinct rate constants.
• Adsorption was found to be enthalpy-controlled for initial anchorage and binding (Ka1).
• Surface denaturation and rearrangement processes were entropy-controlled (Ka2).
• Additives like SDS and CTAB, along with neutral salts, influenced the adsorption rate constants.

Conclusions:

• BSA adsorption kinetics are complex, involving distinct stages with different rate-determining steps.
• The mechanism transitions from enthalpy-driven to entropy-driven processes as adsorption progresses.
• Surface properties and solution conditions significantly modulate protein adsorption behavior, impacting surface denaturation and folding.