Responsive PEI-Fe ₃ O ₄ @CaCO ₃ Nanoparticles: A New Material for Efficient Protein Adsorption and Fast Release

To address the need for rapid protein desorption in protein adsorption applications, we developed and characterized polyethyleneimine-functionalized calcium carbonate nanoparticles coated with ferrosoferric oxide (PEI-Fe 3 O 4 @CaCO[Formula: see text]. This hybrid nanostructure integrates the pH-sensitive properties of calcium carbonate with the magnetic responsiveness of Fe 3 O 4 , enabling quick separation by an external magnetic field within 1[Formula: see text]min. In adsorption experiments with bovine serum albumin (BSA) as a model protein, PEI-Fe 3 O 4 @CaCO 3 achieved a notable adsorption capacity of 197.6[Formula: see text]mg/g at 1[Formula: see text]h, representing 77% of its maximum adsorption potential. Saturation was reached at 256.1[Formula: see text]mg/g within 4[Formula: see text]h. Importantly, the pH-responsive nature of the calcium carbonate component facilitated efficient desorption, achieving a release efficiency of 95.67%[Formula: see text]2.41% within 1[Formula: see text]min in a sodium acetate–acetic acid buffer at pH[Formula: see text]6.2. This pH-responsive and magnetically responsive system demonstrates significant potential for applications requiring fast, controlled protein adsorption and desorption, offering a promising tool for targeted protein recovery in various biochemical and industrial processes.