The Use of Functionalized Silk Fibroin Films as a Platform for Optical Diffraction-Based Sensing Applications

A set of bioactive diffractive optical elements (DOEs) microfabricated were reported using functionalized silk fibroin films and proof-of-principle demonstrations for optical diffraction-based sensing applications including hydration sensing, biological concealment, therapeutic treatment, in vitro and in vivo drug release monitoring upon degradation. To generate a diffractive diffuser, computer simulations were performed by the commercial optical simulation software LightTrans VirtualLab 5. Diffractive diffusers enabled deterministic scattering of light into an arbitrary 2D light pattern. The intensity of the desired light pattern was imported from bitmap files to get the diffractive diffusers presented in GDSII format. In the simulation, the wavelength of input beam was set as 650 nm, and the optical setup was selected as paraxial far-field. The number of phase levels was set as 2 for simplification, which required only a single phase mask. Visual examination of the animals indicated the effectiveness of the therapy, revealing healing wounds at distinct time points of 2, 3, and 4 d, respectively. Further analysis was performed by excising the infected tissue site and assessing the normalized number of colony forming units (CFU) in the homogenate using standard plate counting. A reduction in bacterial count was found for the treated rats.