Preparation Of Heme-Chitosan-SiO₂ Particles And Their Catalytic Activity

Chitosan with biodegradable,non-toxic,good biocompatibility,excellent mechanical properties,chemical stability,excellent performance characteristics,is a good carrier for immobilized enzyme.In particular,the existence of its amino groups in molecule,not only makes it easy to bind with enzyme or protein,but also combine well with metal ions to protect the activity of enzyme from the inhibition by metal ions.These excellent properties make chitosan in the pharmaceutical,chemical,paper marking,agriculture,environmental protection,textile and other fields to have been widely used.In this study,based on the characteristics of chitosan that can be combined with many biological molecules,the chitosan was firstly combined with hemin to form a new composite organic material.Due to the active nature of hemin, this material has the catalytic activity of peroxidase,as an enzyme mimetic.In order to make this mimic enzyme more stable and can be used in a wider pH range,this material was fixed in SiO₂ particles to form a more stable complex with hemin.The experimental results show that the complex of hemin and chitosan could be formed under acidic conditions and be precipitated under alkaline conditions.This complex possessed the catalytic activity of peroxidase,and dissolved under pH 6.45.The successful preparation of heme-Chitosan-SiO₂ particles,which were proved by absorption spectrum analysis and microscopic observation,has resolved the problem that the mimic enzyme expanded and dissolved in acidic solution.Some properties of Hemin-Chitosan-SiO₂ particles had been determined.