Effects of Antibiotics on the Surface Properties of Bovine Serum Albumin Solutions

Abstract

Antibiotics, as widely used antibacterial agents, are commonly delivered through the bloodstream, where they bind to plasma proteins and may alter the surface and rheological properties of blood, thereby influencing drug transport and absorption. Serum albumin, the most abundant carrier protein in plasma, is a well-established model for studying drug–protein interactions. Taking bovine serum albumin (BSA) as the research subject, this study measured the surface tension and contact angle on a silicon nitride substrate of mixed solutions of BSA with three classes of antibioticsquinolones (sparfloxacin, ofloxacin, gatifloxacin), tetracyclines (oxytetracycline, doxycycline, chlortetracycline hydrochloride), and macrolides (erythromycin, erythromycin ethylsuccinate, azithromycin) at two concentrations. The solid surface free energy of silicon nitride was calculated using the Fowkes, OWRK, and Wu methods, and the solid–liquid interfacial tension was obtained via the Young equation. Results show that quinolones exert little influence on the surface properties of BSA solutions; tetracyclines mainly increase surface tension through competitive adsorption and electrostatic effects but do not alter the contact angle; macrolides, owing to the strong hydrophobicity of their 14-membered lactone ring, enhance BSA hydrophobicity, reduce surface tension at high concentration, and lower the solid–liquid interfacial tension on silicon nitride. The findings indicate that hydrophilic–hydrophobic interactions play a decisive role in shaping the surface behavior of antibiotic–BSA systems.