Synthesis And Application In Medical Diagnostic Reagents Of Homogeneous Titania Microspheres

Titanium dioxide（TiO₂）was widely used in coating,photo catalyst,cosmetics and so on.TiO₂ microspheres with homogeneous diameter have been extensively used in the preparation of reflection/filtration/diffusion muiltfunctional layer of dry chemical diagnostic reagents in vitro（dry slices）because of its high reflectivity and homogeneous secondary micron holes of stacking between particles which were used for reflecting,filtering and spreading of serum.Therefore,synthesis of TiO₂ microspheres with homogeneous diameter is one of the key to develope the dry chemical diagnostic reagents in vitro in our country.In this paper,homogeneous diameter TiO₂ microspheres were synthesized by precipitation method.The factors such as ratio of raw materials,reaction solvents,substrate concentration,synthesis time,reaction temperature and calcination temperature were investigated and optimized.The yield of TiO₂ microspheres was 87.7%.The monodisperse particles were TiO₂ and the diameter could reach 2～3μm with an excellent uniformity which were characterized by SEM.The effects of urea on the nucleation rate,growth rate and the time point of the coagulation of colloidal particles of the microspheres were investigated.The TiO₂ reflection/filtration/diffusion muiltfunctional layers were prepared with the TiO₂ microspheres.The factors such as cellulose acetate（CA）dosage,stiring time,surfactant（trixon-100）and serum diffusion time were investigated and optimized.The apertures of TiO₂ multifunction layer prepared at the optimal condition were 4～6 μm and the pore distribution were uniform and dense characterized by SEM;The reflectance of multifunctional layer was greater than 92%in the range of 500～700 nm characterized by reflectance spectrometer;The structure of TiO₂ multifunctional layer prepared by self-made homogeneous TiO₂ microspheres was better than that prepared by commercially available amorphous TiO₂ powder characterized by SEM.Glucose and uric acid dry slices were obtained by covering TiO₂ multifunctional layers on laboratory-made glucose and uric acid reagent layers,respectivity.The results indicated a homodisperse of serum and an excellent reproducibility of this multifunctional layer,and The standard deviation（SD）of reaction spot of parallel samples was 0.04.It formed a significant gradient of color spot after serum spread through multifunctional layer and reacted in reagent layer.Therefore,the homogeneous diameter TiO₂ microspheres synthesized by this route laid a solid experimental foundation for the further application in dry chemical diagnostic reagents in vitro.