The idea of creating photonics tools for sensing, imaging and material characterization has long been pursued and many achievements have been made. Approaching the level of solutions provided by nature however is hindered by routine choice of materials. To this end recent years have witnessed a great effort to engineer mechanically flexible photonic devices using polymer substrates. On the other hand, biodegradability and biocompatibility still remains to be incorporated. Hence biomimetics holds the key to overcome the limitations of traditional materials in photonics design. Natural proteins such as sucker ring teeth (SRT) and silk for instance have remarkable mechanical and optical properties that exceed the endeavors of most synthetic and natural polymers. Here we demonstrate for the first time, toroidal whispering gallery mode resonators (WGMR) fabricated entirely from protein structures such as SRT of Loligo vulgaris (European squid) and silk from Bombyx mori. We provide here complete optical and material characterization of proteinaceous WGMRs, revealing high quality factors in microscale and enhancement of Raman signatures by a microcavity. We also present a most simple application of a WGMR as a natural protein add-drop filter, made of SRT protein. Our work shows that with protein-based materials, optical, mechanical and thermal properties can be devised at the molecular level and it lays the groundwork for future eco-friendly, flexible photonics device design.
A highly accurate, real-time multisensor agent monitor for biomarker detection is required for early detection of kidney diseases. Urine creatinine level can provide useful information on the status of the kidney. We prepare nanostructured surface-enhanced Raman spectroscopy (SERS) substrates without template or lithography, which provides controllable, well-organized nanostructures on the surface, for the quantitative analysis of creatinine concentration in urine. We present our work on sensitivity of the SERS substrate to urine samples collected from diabetic patients and healthy persons. We report the preparation of a new type of SERS substrate, which provides fast (<10 s), highly sensitive (creatinine concentration <0.5 µg/mL) and reproducible (<5% variation) detection of urine. Our method to analyze the creatinine level in urine is in good agreement with the enzymatic method.
Materials surfaces mimic cell like architecture and proteins can be encapsulated by these material surfaces (e.g. a porous glass or gold). Depending on the number and types of surface interactions, this confine environment could destroy the protein or help it maintain its bioactivity. We developed computer models and simulation tools for the understanding of surface-protein interaction at the atomistic levels. At the molecular level, molecular dynamics simulations are very powerful, but the high computational cost of molecular simulations is a drawback. A viable alternative method to study protein-surface interactions is the coarse-grained molecular simulations of simplified models, such as elastic network model. At the atomic interaction level, we used ab initio simulations to calculate the potential between surface and protein atoms.