Polymeric assembled nanoparticles through kinetic stabilization by confined impingement jets dilution mixer for fluorescence switching imaging

Traditional fluorescence switching molecules achieving the state change between on and off states commonly based on UV irradiation. However, it is worth noting that UV irradiation is harmful to both the cancer cells and the normal cells. To achieve fluorescence switching under visible wavelength and avoid complicate molecular design, a fluorophore of 2,4,5,6-tetrakis(carbazol-9-yl)-1,3-dicyanobenzene(4Cz IPN) and a quencher of diarylethene(DAE) were physically incorporated within the biocompatible block copolymer poly(lactic-co-glycolic acid)-b-poly(ethylene glycol)(PLGA-b-PEG) to form 4Cz IPNDAE nanoparticles(NPs) through flash nanoprecipitation(FNP). By using the FNP method, the NPs were prepared within milliseconds in a confined impingement jets dilution(CIJ-D) mixer. Quenching and recovery of fluorescence could achieve in the presence of DAE under 475 nm and 560 nm irradiation.Appropriate structure and fluorescent properties of the nanoparticles can be tuned by external conditions for their efficient fluorescence resonance energy transfer(FRET) in a kinetic stabilization process. This NPs formation process was further optimized by varying the dilution ratio, Reynolds number(Re) and polymer concentration to modulate the mixing and particle nucleation and growth process. The size and fluorescence switching properties of the NPs were systematically investigated in solution and in cellular uptake experiments. This work is anticipated to provide a simple and highly effective engineering strategy for the modulation of fluorescence switching nanoparticles and beneficial to its engineering application.

Noble metal-based high-entropy alloys as advanced electrocatalysts for energy conversion

Noble metal-based high-entropy alloy nanoparticles(NM-HEA NPs) have exhibited brilliant catalytic performance toward electrocatalytic energy conversion and attracted increasing attention. The near-equimolar mixed elements of NM-HEA NPs may result in the unique properties including cocktail effect, high entropy effect and lattice distortion effect, which are beneficial for improving the catalytic performance and reducing the amount of noble metal. Herein, several advanced NM-HEA NPs as electrocatalysts for energy conversion are systematically summarized. The preparation methods of NM-HEA NPs are evaluated as well as the catalytic properties and mechanism are discussed classified by electrocatalytic reactions. Finally,the challenges and prospects in this field are carefully discussed. This review provides an overview on recent advances of NM-HEA electrocatalysts for energy conversion and draws more attention in this infant research field.