| The binding interaction between drug and serum albumin determines the effective blood concentration of drug,which is critical to the pharmacokinetics and pharmacodynamics of the drug.Therefore the binding parameters between drug and serum albumin are important in the research and development of a drug.The most commonly adopted methods to investigate the interaction between a drug and serum albumin are fluorescence measurement,high-performance liquid chromatography(HPLC)and capillary electrophoresis(CE).Among them,CE has attracted extensive attention because of its inherent advantages,such as high separation efficiency,low cost,small sample consumption,and so forth.However the problem of protein non-specifical adsorption onto fused-silica capillary inner surface is detrimental to peak shapes,separation performances and accuracy.Thus,in this work a poly(2-methyl-2-oxazoline)-based(PMOXA-based)protein-resistant coating was immobilized onto capillary inner surface via polydopamine-assisted(PDA-assisted)co-deposition strategy.The as-obtained coated capillary was further used for frontal analysis capillary electrophoresis(FACE)investigation on the interaction between acetaminophen(APAP)and bovine serum albumin(BSA).In this study,a star-shaped copolymer,poly(ethylene imine)-graft-poly(2-methyl-2-oxazoline)(PEI-g-PMOXA)was synthesized.The star-shaped polymer was deposited onto fused-silica capillary inner wall with the assistance of PDA,yielding the PEI-g-PMOXA/PDA coating.SEM measurement on the coated surface and the electroosmotic flow(EOF)in the coated capillary both validated the success in immobilization of the PEI-g-PMOXA/PDA hybrid coating onto capillary inner wall.The coated capillary made good performs on separation of the mixture of four model basic proteins,i.e.cytochrome c,lysozyme,a-trypsinogen A and rinbonuclease A.Theoretical plate numbers were of the magnitude of five orders,about ten-fold larger than those obtained in bare capillary,and the relative standard deviation values(RSDs)in migration time of 30 consecutive runs were less than 0.7%,which were much smaller than those obtained in bare capillary(c.a.5.7%).The results illustrated that the coated capillary possessed great stability and protein-repellant capacity.The PEI-g-PMOXA/PDA-coated capillary was therefore applied to the investigation on the interaction between APAP and BSA by FACE.The binding parameters of APAP-BSA system were 1.39×104 M-1 and 1.08 for binding constant(Ka)and the number of binding site(n),respectively(at 25 ℃ and in 25 mM Tris/HCl butter of pH 7.4).Moreover,in repeatability assessments,the RSDs in Ka and n were 5.1%and 1.4%(n=3)for run-to-run repeatability and 9.0%and 2.4%(n=3)for day-to-day repeatability.The results in FACE investigation were validated by fluorescence measurement(Ka and n were 3.18 ×104 M-1 and 1.19),and the parameters in both methods were similar to those reported by other papers.The results showed that the strategy proposed in this work was in good precision. |
