Converting silicon hydride (–SiH) to oxygen backed silicon hydride (–OSiH) on porous silicon leads to a shift in the wavelength of photoluminescence (PL) maximum from 670 to 605 nm, corresponding to an increase of 0.2 eV on emission energy. The results implied that silicon hydride, which links to the surfaces of silicon nano-crystals (SiNCs) via oxygen atoms, is directly responsible for the wavelength change of the PL peak.
Cesium lead halide (CsPbX3, X = Cl, Br, and I) perovskite nanocrystals (PNCs) have become attractive materials for fluorescence sensing in recent years due to their excellent photoluminescent properties. Because of their ionic properties, PNCs are unstable in polar solvents, making it difficult for them to detect substances in water. Some methods are useful, such as non-homogeneous phase sensing and wrapping an inert layer around the surface of PNCs. However, these methods reduce the sensing efficiency and hinder the interaction of PNCs with sensing substances. In addition, the encapsulated PNCs are more likely to undergo fluorescence quenching and decreased storage stability. In this work, (3-aminopropyl)trimethoxysilane (APTMS) was used to synthesize APTMS PNCs (A-PNCs) by a hot injection one-pot method, and they exhibited satisfactory fluorescence properties, stability, and monodispersity. By introducing ethanol to form a water–ethanol–hexane homogeneous system, the A-PNCs were able to increase their anion-exchange capacity after directly interacting with chloride ions (Cl−) in water. Based on the fluorescence wavelength variation of the A-PNCs, testing for Cl− in human sweat was accomplished in 1 minute, with the advantages of fast speed, high precision, and satisfactory stability. On this basis, the reacted A-PNCs were immobilized on the film with bright fluorescence and color stability, and their tricolor (RGB) values were extracted for visual sensing. Thus, well-dispersed A-PNCs in hexane can rapidly detect chloride ions in water, which will enhance the application of perovskite materials for sensing in polar solvents.
Cardiac microphysiological systems are accurate in vitro platforms that reveal the biological mechanisms underlying cardiopathy, accelerating pharmaceutical research in this field. Current cardiac microphysiological devices and organs-on-chips consist of several layers prepared with complex, multi-step processes. Incorporating inorganic photonic crystals may cause long-term biocompatibility issues. Herein, micropatterned hydrogels with anisotropic structural colors are prepared by locking shear-oriented tunicate cellulose nanocrystals (TCNCs) in hydrogel networks through in situ polymerization, allowing the visualization and monitoring of cardiomyocytes. The anisotropic hydrogels are composed of highly ordered TCNCs with bright interference color and micro-grooved methacrylated gelatin with excellent biocompatibility. The microgroove patterns induce cardiomyocyte alignment and the autonomous beating of cardiomyocytes causes the hydrogels to deform, dynamically shifting the interference color. These micropatterned hydrogels could noninvasively monitor real-time changes of cardiomyocytes under pharmaceutical treatment and electrical stimulation through wavelength shifts in the transmittance spectra. This system provides a new way to detect the beat rate of cardiac tissue and it may contribute to high throughput develop.
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