The study of titanium dioxide modification by glutaraldehyde and its application of immobilized penicillin acylase

Abstract In this work, titanium dioxide particle was firstly modified with glutaraldehyde, and modification conditions, i.e. particle size ( d ), active temperature ( T a ), modification temperature ( T m ), modification time ( t m ), pH value, aldehyde ethanol ratio ( R a ) and ethanol ratio ( R e ), were studied and optimized adopting grafting rate ( G r ) as the optimizing index, the ultraviolet-visible spectrophotometry as characterization method, and the obtained optimal modification conditions were d  = 3.3 μm, T a  = 120 °C, T m  = 45 °C, t m  = 30 h, pH = 6.0, R a  = 1:10 and R e  = 100%. Under the optimal conditions, G r of glutaraldehyde arrived at 50%. Thereafter, a series of modified titanium dioxide with G r in the range of [8%, 46%] and with G r  = 30% obtained from different modification conditions were adopted to study the immobilization of penicillin G acylase (PGA), during this process, the ultraviolet-visible spectrophotometry of 6-aminopenicillanic acid was conscripted as characterization method, the enzyme loading capacity ( ELC ), the enzyme activity ( EA ) and enzyme activity retaining ratio ( EAR ) were explored, and results documented with the increase of G r , ELC , EA and EAR increased. As G r kept as a similar level, ELC, EA and EAR also showed a similar value. Finally, the structure of titanium dioxide, glutaraldehyde modified titanium dioxide and PGA immobilized titanium dioxide was characterized by the flourier transform infrared spectroscopy (FTIR), and results exhibited aimed samples were obtained successfully.