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Interpreting macroscopic stimulus into visible signals with nanomaterials is crucial for the development of smart nanoprobes for in situ monitoring or imaging. Building nanoprobes to translate pH and temperature stimuli into a single-color signal with a “turn-on” feature is a great challenge. Here, we aim to interpret temperature and pH stimuli into a single-color signal via aggregation-induced emission (AIE) active reversible micelles. The dual-responsive block copolymers, PNIPAM-b-P­(DPA-co-TPE) and P­(NIPAM-co-TPE)-b-PDPA, were conveniently prepared with similar block length but different TPE position through reversible addition–fragmentation chain-transfer (RAFT) polymerization. Both dual-responsive polymers could self-assemble into reversible micelles with AIE-active turn-on fluorescence under the stimulus of pH or temperature, respectively. The fluorescence intensity enhanced 7-fold for PNIPAM-b-P­(DPA-co-TPE) and 3-fold for P­(NIPAM-co-TPE)-b-PDPA by tuning the solution pH or temperature, which further showed a robust “on–off” reversibility of fluorescence signal. Through coassembly, the stimulus of either pH or temperature could be identified based on the different intensity and expansion of the emission spectra, which was further confirmed in vitro for cell imaging. Definitely, this work provides a promising approach to interpret minor pH or temperature changes in solutions and in cells.

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To obtain a self-disinfecting surface to combat nosocomial infections, in situ synthesis of the MoO 3-SiO 2-Ag 2 O nanocomposite antibacterial coating was prepared onto Ti-6Al-4V substrate via a double cathode glow discharge technique conducted in a Ar + O 2 gas mixture. The phase composition, microstructure and chemical structure of the as-prepared coating were systematically characterized by means of a series of microscopic examination methods. The microstructure of the coating exhibited an amorphous/nanocrystalline architecture, and both the MoO 3 and Ag 2 O crystallites were evenly embedded in an amorphous SiO 2 matrix. Photocatalytic activities of the coating were evaluated by photodegradation of rhodamine B (RhB) dye. The results showed that the introduction of Ag 2 O enhanced photocatalytic activity of the MoO 3-SiO 2 nanocomposite coating. In vitro antibacterial activity of the MoO 3-SiO 2-Ag 2 O coating against Gram-negative bacteria, Gram-positive bacteria and fungi were investigated and compared with that of the MoO 3-SiO 2 coating under both dark and visible light conditions. The MoO 3-SiO 2-Ag 2 O coating possessed higher bactericidal activities than the MoO 3-SiO 2 coating, due to the combined effects of surface hydrophobicity, the release of Ag + ions, surface acidic reaction and photocatalytic activity.

Distributed acoustic sensing techniques based on Rayleigh scattering have been widely used in many applications due to their unique advantages, such as long-distance detection, high spatial resolution, and wide sensing bandwidth. In this paper, we provide a review of the recent advancements in distributed acoustic sensing techniques. The research progress and operation principles are systematically reviewed. The pivotal technologies and solutions applied to distributed acoustic sensing are introduced in terms of polarization fading, coherent fading, spatial resolution, frequency response, signal-to-noise ratio, and sensing distance. The applications of the distributed acoustic sensing are covered, including perimeter security, earthquake monitoring, energy exploration, underwater positioning, and railway monitoring. The potential developments of the distributed acoustic sensing techniques are also discussed.

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