Two kinds of unique pH-dependent magnetic nanoadsorbents based on silicacoated magnetic nanoparticles (SMNPs) and amino-silica coated magneticnanoparticles (ASMNPs) have been exploited for selective separation of proteins.With different isoelectric points, silica coated magnetic nanoadsorbents (SMNAs)and amino-silica coated magnetic nanoadsorbents (ASMNAs) can respectivelyadsorb proteins with different charges. The interactions between proteins andmagnetic nanoadsorbents changed with the solution pH. Thus, the adsorption ordesorption between proteins and magnetic nanoadsorbents can be controlled bychanging the solution pH according to the charge of the proteins. And the magneticnanoadsorbents can be separated and recycled simply with a magnet. As modeladsorbates, Cyt-c and BSA are selectively separated from simple protein mixtures withSMNAs and ASMNAs respectively. Cyt-c was adsorbed on SMNAs at pH 8.0 at0.160 mg mg−1. And BSA was adsorbed on ASMNAs at pH 5.0 at0.142 mg mg−1.
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