Dissolving microneedle system containing Ag nanoparticle-decorated silk fibroin microspheres and antibiotics for synergistic therapy of bacterial biofilm infection.

Most cases of delayed wound healing are associated with bacterial biofilm infections due to high antibiotic resistance. To improve patient compliance and recovery rates, it is critical to develop minimally invasive and efficient methods to eliminate bacterial biofilms as an alternative to clinical debridement techniques. Herein, we develop a dissolving microneedle system containing Ag nanoparticles (AgNPs)-decorated silk fibroin microspheres (SFM-AgNPs) and antibiotics for synergistic treatment of bacterial biofilm infection. Silk fibroin microspheres (SFM) are controllably prepared in an incompatible system formed by a mixture of protein and carbohydrate solutions by using a mild all-aqueous phase method and serve as biological templates for the synthesis of AgNPs. The SFM-AgNPs exert dose- and time-dependent broad-spectrum antibacterial effects by inducing bacterial adhesion. The combination of SFM-AgNPs with antibiotics breaks the limitation of the antibacterial spectrum and achieves better efficacy with reduced antibiotic dosage. Using hyaluronic acid (HA) as the soluble matrix, the microneedle system containing SFM-AgNPs and anti-Gram-positive coccus drug (Mupirocin) inserts into the bacterial biofilms with sufficient strength, thereby effectively delivering the antibacterial agents and realizing good antibiofilm effect on Staphylococcus aureus-infected wounds. This work demonstrates the great potential for the development of novel therapeutic systems for eradicating bacterial biofilm infections.

Novel thermo and ion-responsive copolymers based on metallo-base pair directed host-guest complexation for highly selective recognition of Hg2+ in aqueous solution.

The development of materials with highly selective recognition towards Hg2+ is of great significance in environmental monitoring. Herein, a novel thermo-responsive copolymer with Hg2+ recognition property is prepared via thermally-initiated copolymerization of 5'-O-Acryloyl 5-methyl-uridine (APU) and N-isopropylacrylamide (NIPAM). The chemical structure and stimuli-sensitive properties of poly(N-isopropylacrylamide-co-5-methyl-uridine) (P(NIPAM-co-APU)) linear polymers and hydrogel are thoroughly investigated. At the supramolecular level, P(NIPAM-co-APU) linear polymers could respond to both temperature and Hg2+ stimuli with highly selective recognition towards Hg2+ over other 18 metal ion species (at least 5 fold difference) and common anions. Upon capturing Hg2+ by APU units as host metal receptors, the lower critical solution temperature (LCST) of P(NIPAM-co-APU, PNU-7 and PNU-11) linear polymers are significantly shifted more than 10 °C due to the formation of stable APU-Hg2+-APU directed host-guest complexes. Accordingly, at the macroscopic level, P(NIPAM-co-APU) hydrogel display selective and robust recognition of Hg2+ under optimum conditions, and its maximum Hg2+ uptake capacity was 33.1 mg g-1. This work provides a new option for Hg2+ recognition with high selectivity, which could be facilely integrated with other smart systems to achieve satisfactory detection of environmental Hg2+.