The Interference Effect of Silica Colloidal Crystal Films and Their Applications on Biosensing

With the aim to develop better and reliable interference effective substrates, silica colloidal crystal films with different sphere di-ameters and film thicknesses were successfully made by an improved vertical deposition method and a systematic investigation of their reflectometric interference spectroscopy (RIfS) properties was presented in this work. The influence of silica sphere diameter and film thickness on the RIfS signals was studied. Results showed that the film thickness is the key factor of RIfS signals. A RIfS system was set up by using the silica colloidal crystal film as interference effective substrates. The influence of film thickness on response to refractive index changes of the proposed system was also investigated. Considering the influence of film thickness on RIfS signals and refractive index response together, silica colloidal crystal films with a thickness between 4 and 6 μm were chosen for sensor construction. Monitoring the digestive process of gelatin with trypsin was also demo...