TiO_2 Optical Sensor for Amino Acid Detection

摘要

A novel optical sensor based on TiO_2 nanoparticles for Valine detection has been developed. In the presented work, commercial TiO_2 nanoparticles (Sigma Aldrich, particle size 32 run) were used as sensor templates. The sensitive layer was formed by a porphyrin coating on a TiO_2 nanostructured surface. As a result, an amorphous layer between the TiO_2 nanostructure and porphyrin was formed. Photoluminescence (PL) spectra were measured in the range of 370-900 ran before and after porphyrin application. Porphyrin adsorption led to a decrease of the main TiO_2 peak at 510 nm and the emergence of an additional peak of high intensity at 700 nm. Absorption spectra (optical density vs. wavelenght, measured from 300 to 1100 nm) showed IR shift Sorret band of prophiryn after deposition on metal oxide. Adsorption of amino acid quenched PL emission, related to porphyrin and increased the intensity of the TiO_2 emission. The interaction between the sensor surface and the amino acid leads to the formation of new complexes on the surface and results in a reduction of the optical activity of porphyrin. Sensitivity of the sensor to different concentrations of Valine was calculated. The developed sensor can determine the concentration of Valine in the range of 0.04 to 0.16 mg/ml.