Nanofiber Hydrogel Drug Delivery System for Prevention of Postsurgical Intestinal Adhesion.

Intestinal adhesion is one of the complications that occurs more frequently after abdominal surgery. Postsurgical intestinal adhesion (PIA) can lead to a series of health problems, including abdominal pain, intestinal obstruction, and female infertility. Currently, hydrogels and nanofibrous films as barriers are often used for preventing PIA formation; however, these kinds of materials have their intrinsic disadvantages. Herein, we developed a dual-structure drug delivery patch consisting of poly lactic-co-glycolic acid (PLGA) nanofibers and a chitosan hydrogel (NHP). PLGA nanofibers loaded with deferoxamine mesylate (DFO) were incorporated into the hydrogel; meanwhile, the hydrogel was loaded with anti-inflammatory drug dexamethasone (DXMS). The rapid degradation of the hydrogel facilitated the release of DXMS at the acute inflammatory stage of the early injury and provided effective anti-inflammatory effects for wound sites. Moreover, PLGA composite nanofibers could provide sustained and stable release of DFO for promoting the peritoneal repair by the angiogenesis effects of DFO. The in vivo results indicated that NHP can effectively prevent PIA formation by restraining inflammation and vascularization, promoting peritoneal repair. Therefore, we believe that our NHP has a great potential application in inhibition of PIA.

Synthesis of curcumin-quaternized carbon quantum dots with enhanced broad-spectrum antibacterial activity for promoting infected wound healing.

With the increasing incidence of multidrug-resistant antibacterial infections worldwide, developing new antibiotics to fight bacterial infections is urgent. The natural product curcumin has favorable antioxidant and anti-inflammatory effects, but poor water solubility greatly limits its bioavailability, bioactivity and clinical application. Herein, to improve the bioactivity and enhance broad-spectrum antibacterial of curcumin, we synthesized quaternized carbon quantum dots (Q-CQDs) derived from the natural curcumin and 2,3-epoxypropyltrimethylammonium chloride (GTA) with highly solubility and stability by "double-thermal" method. It is proposed that the surfaces of Q-CQDs would still remain the active groups of curcumin and quaternary ammonium to boost the antibacterial activity. Experimental results reveal that the Q-CQDs possess excellent broad-spectrum antibacterial activity and the activity is significantly higher than that of natural curcumin. Investigation of the antibacterial mechanism of Q-CQDs showed that Q-CQDs functionalized with -N+(CH3)3 had strong adherence behavior on the bacterial cell membrane. Like a "Trojan Horse", the bacterial cells lost their integrity, and the entry of Q-CQDs caused ROS generation and the efflux of cytoplasmic DNA and RNA, leading to the death of bacteria. The bacterial resistance of Q-CQDs was not observed, and Q-CQDs did not cause hemolysis and cytotoxicity. In vivo, the S. aureus-infected wounds, E. coli-infected wounds and mixed bacteria infected wounds healing tests with mice model indicate that Q-CQDs inhibited the bacterial population at the wound site, reduced inflammation and promoted wound healing. These results suggested that the Q-CQDs are a potential antibacterial candidate for clinical infected-wound healing applications and even bacteria resistant infections.

Boosting the oxidase-like activity of platinum nanozyme in MBTH-TOOS chromogenic system for detection of trypsin and its inhibitor.

Nanozymes, as a new type of artificial enzyme, have recently become a research hotspot in the field of catalysis and biomedicine. However, the application of nanozyme is limited by catalytic activity changes of different substrates and low specificity. This work shows that citrate-capped platinum nanoparticles (Cit-PtNPs) exhibit stronger oxidase-like activity than other platinum nanozymes at different pH when 3-methyl-2-benzothiazolinonehydrazone hydrochloride (MBTH) and n-ethyl-n- (2-hydroxy-3-sulfopropyl)-m-toluidine sodium salt (TOOS) were used as chromogenic substrates. This phenomenon has important reference value for different nanozymes to choose chromogenic substrates in catalysis. In MBTH-TOOS chromogenic system, MBTH (-NH) radical is first produced during the reaction through catalytic oxidation of Cit-PtNPs, which reacts with TOOS to produce a colorless compound. The blue-purple quinoid dye was produced through the dismutation of the colorless compound. The catalytic mechanism of the oxidase-like activity of Cit-PtNPs is that two-electron reduction process and four-electron reduction process are simultaneously carried out in the catalytic process. Furthermore, to solve the problem of low specificity of metal nanozymes, protamine is designed as aggregation promoter of Cit-PtNPs and the specifichydrolysis substrate of trypsin. In this work, it can achieve one-step detection of trypsin by the boosting oxidase activity of Cit-PtNPs at pH8. The catalytic activity of Cit-PtNPs is proportional to the concentration of trypsin. The linear range for trypsin is 1.0-70.0 ngmL-1 and the limit of detection is measured to be 0.6 ngmL-1. This novel method has also been successfully applied to the detection of inhibitors and trypsin in urine samples.