The invention provides for compositions and process for fabricating an optical reflector constructed from biocompatible and bioresorbable silk fibroin proteins. For example, the silk retroreflectors may be built based on millimeter size microprism arrays to rotate the image plane of imaged cortical layers, thus enhancing the amount of photons that are detectable in the reflected direction when inserted in a sample to be analyzed, and ultimately increasing in contrast ratio in multiphoton microscopy. Such device can be used as a label-free, biocompatible, bioresorbable, implantable device for various applications ranging from medical imaging/diagnostics, drug/therapeutic delivery, to food chain safety and environmental monitoring.
