Study On The Interactions Between Proteins And Polystyrene-polyacrylic Acid(PS-PAA)Spherical Polyelectrolyte Brushes With Different PAA Chain Lengths

The interactions between polystyrene-polyacrylic acid (PS-PAA) spherical polyelectrolyte brushes with different PAA chain lengths and Bovine Serum Albumin (BSA) were studied by physical adsorption in phosphate buffer solution (PBS) in this paper. It was discovered that the amount of BSA physically adsorbed on per milligram PS-PAA spherical polyelectrolyte brushes decreased to a minimum of 33μg/mg brushes as the PAA chain lengths increase to 25nm and remained unchanged when the chain lengths get longer.Then, the interactions between PS-PAA spherical polyelectrolyte brushes with different PAA chain lengths and streptavidin (SA) were studided systemically through chemical coupling.The carboxyl of PS-PAA spherical polyelectrolyte brushes were activated by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-Hydroxysuccinimide (NHS). SA was chemically coupled to the PS-PAA spherical polyelectrolyte brushes via amide bond formed between carboxyl and amino on SA in PBS. The carboxyl quantity per PS-PAA spherical polyelectrolyte brushes was determined by conductance titration. It was shown that the amount of SA chemically immobilized on PS-PAA spherical polyelectrolyte brushes increased with the increase of PAA chain length and carboxyl quantity. Besides, the growing trend of SA immobilization amount becomes more prominent with the increase of PAA chain length and the quantity of carboxyl groups on PS-PAA brushes.Finally, the biotin binding capacity of chemically coupled SA on PS-PAA spherical polyelectrolyte brushes was evaluated via enzyme competitive inhibition experiment in PBS.?It was revealed that the chain length has little to do with the biotin binding capacity of SA when the SA density on PS-PAA was low. When the PAA chain length was short (12.5nm), every SA chemically coupled could bind about 2 biotins averagely no matter how many SAs were immobilized on PS-PAA spherical polyelectrolyte brushes.