Visual Detection of Dopamine with CdS/ZnS Quantum Dots Bearing by ZIF-8 and Nanofiber Membranes.

Dopamine (DA) is a widely present, calcium cholinergic neurotransmitter in the body, playing important roles in the central nervous system and cardiovascular system. Developing fast and sensitive DA detection methods is of great significance. Fluorescence-based methods have attracted much attention due to their advantages of easy operation, a fast response speed, and high sensitivity. This study prepared hydrophilic and high-performance CdS/ZnS quantum dots (QDs) for DA detection. The waterborne CdS/ZnS QDs were synthesized in one step using the amphiphilic polymer PEI-g-C14, obtained by grafting tetradecane (C14) to polyethyleneimine (PEI), as a template. The polyacrylonitrile nanofiber membrane (PAN-NFM) was prepared by electrospinning (e-spinning), and a metal organic frame (ZIF-8) was deposited in situ on the surface of the PAN-NFM. The CdS/ZnS QDs were loaded onto this substrate (ZIF-8@PAN-NFM). The results showed that after the deposition of ZIF-8, the water contact angle of the hydrophobic PAN-NFM decreased to within 40°. The nanofiber membrane loaded with QDs also exhibited significant changes in fluorescence in the presence of DA at different concentrations, which could be applied as a fast detection method of DA with high sensitivity. Meanwhile, the fluorescence on this PAN-NFM could be visually observed as it transitioned from a blue-green color to colorless, making it suitable for the real-time detection of DA.

Bienzymatic synergism of vanadium oxide nanodots to efficiently eradicate drug-resistant bacteria during wound healing in vivo.

Antibiotic resistance is a common phenomenon observed during treatment with antibacterials. Use of nanozymes, especially those with synergistic enzyme-like activities, as antibacterials could overcome this problem, but their synthesis is limited by their high cost and/or complex production process. Herein, vanadium oxide nanodots (VOxNDs) were prepared via a one-step bottom-up ethanol-thermal method using vanadium trichloride as the precursor. VOxNDs alone possess bienzyme mimics of peroxidase and oxidase. Accordingly, highly efficient antibacterials against drug-resistant bacteria can be obtained through synergistic catalysis; the oxidase-like activity decomposes O2 to generate superoxide anion radical (O2-) and hydroxyl radicals (OH), and the intrinsic peroxidase-like activity can further induce the production of OH from external H2O2. Consequently, H2O2 concentration could decrease up to four magnitude orders with VOxNDs to achieve an antibacterial efficacy similar to that of H2O2 alone. Wound healing in vivo further confirms the high antibacterial efficiency, good biocompatibility, and application potential of the synergistic antibacterial system due to the "nano" structure of VOxNDs. The method of synthesis of nanodot antibacterials described in this paper is inexpensive, and the results of this study reveal the multi-enzymatic synergism of nanozymes.

Intestinal alkaline phosphatase release is not associated with chylomicron formation.

Intestinal alkaline phosphatase (IAP) is one of the major sources of alkaline phosphatase in circulation. It is secreted into the intestinal lumen, serum, and lymph. After the ingestion of lipid, lymphatic alkaline phosphatase secretion increases significantly. We have found that the nonabsorbable fat olestra is unable to stimulate lymphatic alkaline phosphatase secretion. We also found that the hydrophobic surfactant Pluronic L-81, which blocks chylomicron formation, fails to inhibit this increase in lymphatic alkaline phosphatase secretion. These results suggest that it is the lipid uptake into the mucosa and/or reesterification to form triacylglycerols, but not the formation of chylomicrons, that is necessary for the stimulation of the secretion of alkaline phosphatase into the lymph.