Liquefied Polysaccharides-Based Polymer with Tunable Condensed State Structure for Antimicrobial Shield by Multiple Processing Methods

A Photocurable Polysaccharide-Based Hydrogel Delivery of Polydeoxyribonucleotide-Loaded Vectors for Wound Treatment

The wounds caused by war, accidents, and diseases require timely and effective treatment. Polysaccharides, as natural macromolecules, have good biocompatibility and unique functions, and are excellent substrates for constructing new wound dressings. Short-chain chitosan (SCS) has good water solubility and, importantly, retains a large number of active amino groups. We first introduce double bonds to SCS. This chitosan derivative can be entangled with sodium alginate (SA) through electrostatic interaction. The flowing sol can be applied to a wound with an irregular shape. Under the initiation of a photoinitiator, the internal double bonds are broken and cross-linked to form a gel. The prepared hydrogel wound dressing exhibited good antibacterial properties and can provide a microenvironment conducive to wound repair. A polydeoxyribonucleotide (PDRN) has been proven to have encouraging therapeutic effects for wound healing. PDRN can be condensed by branched polyethylenimine (PEI) to form a nucleic acid delivery system, which can be efficiently uptaken by cells. The cooperation of hydrogel and nucleic-acid-based therapy presented good results in a mouse full-thickness skin wound model.

A Cascade BIME-Triggered Near-IR Cyanine Nanoplatform for Enhanced Antibacterial Photodynamic Therapy

The long-standing misuse of antibiotics has accelerated the emergence of drug-resistant bacteria, which gives rise to an urgent public health threat. Antibacterial photodynamic therapy (aPDT), as a burgeoning and promising antibacterial strategy, plays an essential role in avoiding the evolution of drug-resistant microbes. However, it is hard for conventional photosensitizers to achieve satisfactory antibacterial efficacy because of the complex bacterial infectious microenvironment (BIME). Herein, a cascade BIME-triggered near-infrared cyanine (HA-CY) nanoplatform has been developed via conjugating cyanine units to biocompatible hyaluronic acid (HA) for enhanced aPDT efficacy. The HA-CY nanoparticles can be dissociated under the overexpressed hyaluronidase in BIME to release a cyanine photosensitizer. Meanwhile, cyanine can be protonated under acidic BIME, where protonated cyanine can efficiently adhere to the surface of a negatively charged bacterial membrane and increase singlet oxygen production due to intramolecular charge transfer (ICT). Experiments in the cellular level and animal model proved that the BIME-triggered activation of aPDT could remarkably boost aPDT efficacy. Overall, this BIME-triggered HA-CY nanoplatform presents great promise for overcoming the dilemma of drug-resistant microbes.

One-step curing process of conductive paste based on a UV pulse laser for a frequency selective surface

A frequency selective surface (FSS) is a two-dimensional periodic array structure, in which a common structure is composed of conductive paste and metal film. An ultraviolet (UV) pulse-laser-induced curing of conductive paste towards FSS was used to simultaneously realize the efficient curing of conductive paste and the removal of surplus materials. Through simple defocus control of the UV pulse laser when irradiating the workpiece, this technology was capable of reducing the energy density and increasing the irradiation range, thus preventing the conductive paste from being ablated and achieving efficient curing. In this context, the curing process of UV curable conductive paste was systematically studied through the Ohmic resistance and bonding force of the cured conductive paste. The curing effects of various conductive paste thicknesses and different laser scanning times at a certain laser scanning speed were also analyzed. The results showed that, after a controllable defocusing treatment, the UV pulse laser could effectively solidify the conductive paste and realize the electrical connection of materials on both sides of the pattern. The peel strength of the conductive paste was greater than 7.1 N/cm. However, the pulse laser curing method needs a longer curing time when compared with the continuous UV curing method.