Droplet microfluidics technology is recently a highly interesting platform in material fabrication. Droplets can precisely monitor and control entire material fabrication processes and are superior to conventional bulk techniques. Droplet production is controlled by regulating the channel geometry and flow rates of each fluid. The micro-scale size of droplets results in rapid heat and mass-transfer rates. When used as templates, droplets can be used to develop reproducible and scalable microparticles with tailored sizes, shapes and morphologies, which are difficult to obtain using traditional bulk methods. This technology can revolutionize material processing and application platforms. Generally, microparticle preparation methods involve three steps: (1) the formation of micro-droplets using a microfluidics generator; (2) shaping the droplets in micro-channels; and (3) solidifying the droplets to form microparticles. This review discusses the production of microparticles produced by droplet microfluidics according to their morphological categories, which generally determine their physicochemical properties and applications.

Quantification of trace serum circulate microRNAs is extremely important in clinical diagnosis but remains a great challenge. Herein we developed an ultrasensitive platform for microRNA 141 (miR-141) detection based on a silver coated gold nanorods (Au@Ag NRs) etching process accompanied by surface plasmon resonance (SPR) shift. Both SPR absorption and scattering responses were monitored. Combined amplification cascades of catalyzed hairpin assembly (CHA) and hybridization chain reaction (HCR) with the sensitive SPR responses of plasmonic Au@Ag NRs, the proposed bioassay exhibited ultrahigh sensitivity toward miRNA-141 with dynamic range from 5.0 × 10 M to 1.0 × 10 M. With target concentration higher than 1.0 × 10 M, the color of the solution changed obviously that could be observed with naked eyes. Under dark-field microscopy observation of individual particle, a limit of detection down to 50 aM could be achieved. Owing to the superior sensitivity and selectivity, the proposed method was applied to detecting trace microRNA in serum. Similar SPR assays could be developed simply by redesigning the switching aptamer for the detections of other microRNAs or targets such as small molecule, DNA, or protein. Considering the convenient operation, good performance and simple observation modes of this method, it may have great potential in trace bioanalysis for clinical applications.

Photoluminescence ͑PL͒ spectra of as-made porous Si samples were obtained in a wide peak-wavelength range. After exposure to air or coupling with C 60 molecules, the PL peak shifts to a pinning wavelength within the range of 610-630 nm. This pinning wavelength is almost independent of the size of the original porous Si nanocrystallites and both redshifting and blueshifting can occur for different sizes. A self-consistent effectivemass calculation shows that the SivO binding states are responsible for the radiation of this pinning wavelength and the blueshift for the large nanocrystallites is due to the additional potential modulation within the Si nanocrystallite by the long-range Coulomb interaction of oxygen ions.

Perovskites have attracted intensive attention as promising materials for the application in various optoelectronic devices due to their large light absorption coefficient, high carrier mobility, and long charge carrier diffusion length. However, the performance of the pure perovskite nanocrystals-based device is extremely restricted by the limited charge transport capability due to the existence of a large number of the grain boundary between perovskite nanocrystals. To address these issues, a high-performance photodetector based on all-inorganic CsPbBr 3 perovskite nanocrystals/2D non-layered cadmium sulfide selenide heterostructure has been demonstrated through energy band engineering with designed typed-II heterostructure. The photodetector exhibits an ultra-high lightto-dark current ratio of 1.36 × 10 5 , a high responsivity of 2.89 × 10 2 A W −1 , a large detectivity of 1.28 × 10 14 Jones, and the response/recovery time of 0.53s/0.62 s. The enhancement of the optoelectronic performance of the heterostructure photodetector is mainly attributed to the efficient charge carrier transfer ability between the all-inorganic CsPbBr 3 perovskites and 2D cadmium sulfide selenide resulting from energy band alignment engineering. The charge carriers' transfer dynamics and the mechanism of the CsPbBr 3 perovskites/2D non-layered nanosheets interfaces have also been studied by state-state PL spectra, fluorescence lifetime imaging microscopy, time-resolved photoluminescence spectroscopy, and Kelvin probe force microscopy measurements.

Great effort has been made in exploring techniques and catalysts for O2•− production but they always work efficiently in either acidic or base environment. Presented here is the design of a unique oxidase mimic catalyst comprising self‐assembled hemin molecules on graphdiyne (hemin/GDY) for efficient O2•− generation in wide pH ranges. Hemin molecules anchor uniformly across the carbon frame of GDY to enable atomic distribution of the active metal sites, delivering a O2•− production rate of 35.7 and 2.3 times than that of hemin and hemin/graphene, respectively. In particular, hemin/GDY can efficiently produce O2•− in acidic, alkaline, and neutral environments, delivering a wide pH behavior. Its oxidase mimic ability is demonstrated for sensing glutathione molecules in cell assays, exhibiting high selectivity, long linear range. This work opens a promising design strategy toward efficient oxidase mimic catalysts for various applications.