Fabrication of Buoyancy-Assisted Separable HGM@SiO ₂ -NH ₂ Composite and Its Application in Protein Adsorption-Desorption

To address the need for efficient and readily separable adsorbents in protein purification, this study developed a novel amino-functionalized silica-coated hollow glass microsphere composite (HGM@SiO 2 -NH 2 ) using commercially available hollow glass microspheres as the substrate. This material integrates the buoyancy of hollow glass microspheres with a functional silica-amine shell designed for electrostatic protein capture. Characterization via scanning electron microscopy, dynamic light scattering, zeta potential measurement, Fourier transform infrared spectroscopy, and acid.base titration confirmed the successful layered construction of the material, revealing a surface amino group density of 15.99 mmol/g along with excellent dispersion and buoyancy-driven separation characteristics in aqueous media.Adsorption experiments using bovine serum albumin (BSA) as a model protein demonstrated a high adsorption capacity of 43.7 mg/g. The adsorption process was rapid, reaching a approximately 38 mg/g (about 86% of the equilibrium capacity) within 30 min, and was primarily governed by electrostatic interactions, as evidenced by optimal performance at pH 6.5. Kinetic studies showed strong adherence to the pseudo-second-order kinetic model, while equilibrium data fitted well with the Langmuir isotherm model, indicating monolayer adsorption onto homogeneous sites. Furthermore, efficient desorption (84.5%) was achieved within 30 min using a high-concentration salt solution. The material also exhibited good stability over multiple cycles, retaining approximately 70% of its initial adsorption capacity after six consecutive adsorption.desorption cycles.This work demonstrates that HGM@SiO 2 -NH 2 is a promising and reusable adsorbent platform that combines efficient protein binding via electrostatic interactions with convenient buoyancy-assisted separation. These findings lay a solid foundation for its potential application in bioseparation processes.