Preparation of Dopamine/Titania Hybrid Nanoparticles through Biomimetic Mineralization and Titanium(IV)–Catecholate Coordination for Enzyme Immobilization

Abstract

In this study, a facile approach is proposed to prepare dopamine/titania hybrid nanoparticles (DTHNPs), which are synthesized via directly blending titanium(IV) bis(ammonium lactato) dihydroxide (Ti-BALDH) and dopamine aqueous solution. The amino group in dopamine is mainly in charge of inducing the hydrolysis and condensation of titanium precursor to form titania, and the catechol group in dopamine acts as an organic ligand to form titanium(IV)–catecholate coordination. These DTHNPs were characterized by tranmission electron miscroscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The morphology of DTHNPs is changed from slightly cotton-shaped aggregates to monodisperse nanoparticles with the increase of dopamine concentration. As a model enzyme, catalase (CAT) is entrapped in the DTHNPs during the nanoparticle preparation process. Surprisingly, the entrapment efficiency of CAT can be high up to nearly 100%, and no enzyme leakage could be detected. Moreover, immobilized CAT possesses 90% the catalytic activity of free enzyme.