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Gradient Protein Thin-Film-Based Bragg's Mirror
Fei Tao1,2,3, Yali Li1,2,3, Qian Han1,2,3
1Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710119, China.
Abstract:
Conventional structural color sensors with an even thickness can hardly detect tiny structural changes caused by analytes at extremely low concentrations. Herein, we construct a gradient protein thin-film-based Bragg's mirror, which reveals a highly effective signaling translation from the 3D gradient surface to 2D interference patterns and thus realizes an extremely high sub 0.5 Å of spatial resolution by using a simple CCD camera, exhibiting 1000-fold improvement than the color recognition. Bragg's mirror consists of responsive "core-shell" structural protein nanocrystals, which is applied for sensing humidity and putrescine vapor through adsorption-swelling and crystallization-swelling mechanisms, respectively. Through an exposure-development strategy, we successfully demonstrated the real-time monitoring of seafood spoilage in high-humidity environments. Compared to professional spectrometer-based reflectance measurements, our Bragg pattern analysis shows 2.6-5× sensitivity improvement in both detection modes. This work introduces a means to open the door to types of high-performance and low-cost colorimetric sensors that are competitive with and offer greater functionality than bulky/expensive modern optical sensors.
