Promoting Electrochemical Nitrate Reduction to Ammonia on Silver Nanocrystals Doped with Iron Series Elements.

Electrochemical nitrate reduction to ammonia (NRA) is a promising approach to remove environmental pollutants while producing green NH3 under ambient conditions. Ag-based nanomaterials have been used in NRA but their iron series elements (Fe, Co, Ni) doping has not been explored yet. Herein, an effective and versatile doping strategy of Ag nanocrystals by iron series elements for efficient NRA is presented. Experimental results show that doping with Fe, Co or Ni can improve the NRA activity. Among the catalysts, AgCo delivers the best performance with a Faraday efficiency (FE) of 88.3 % and ammonia selectivity of 97.4 % at-0.23 V vs RHE, which is 1.9 and 6.2 times higher than that of plain Ag (46.4 % FE and 15.8 % selectivity), respectively. A highest NO3 - conversion rate of AgCo (91.8 %) is achieved, which maintains 16.4 ppm NO3 --N in 4 hours, meeting the drinking water level (~15 ppm NO3 --N). Moreover, the FE, selectivity, conversion rate of AgCo do not decay after the four consecutive cycles. It is found that Co doping can effectively induce the change of Ag d-band center for optimized NRA. This work reveals doping effects of iron series elements on Ag-based catalysts, and shows potential practical application in NRA.

Smart zwitterionic coatings with precise pH-responsive antibacterial functions for bone implants to combat bacterial infections.

Hydrophilic antifouling coatings based on zwitterionic polymers have been widely applied for the surface modification of bone implants to combat biofilm formation and reduce the likelihood of implant-related infections. However, their long-term effectiveness is significantly limited by the lack of effective and precise antibacterial activity. Here, a pH-responsive smart zwitterionic antibacterial coating (PSB/GS coating) was designed and robustly fabricated onto titanium-base bone implants by using a facile two-step method. First, dopamine (DA) and a poly(sulfobetaine methacrylate-co-dopamine methacrylamide) (PSBDA) copolymer were deposited on implants via mussel-inspired surface chemistry, resulting in a hydrophilic base coating with abundant catechol residues. Next, an amino-rich antibiotic, gentamicin sulfate (GS), was covalently linked to the coating through the formation of acid-sensitive Schiff base bonds between the amine groups of GS and the catechol residues present in both the zwitterionic polymer and the DA component. During the initial implantation period, the hydrophilic zwitterionic polymers demonstrated the desired anti-fouling properties that could effectively reduce protein and bacterial adhesion by over 90%. With time, the bacterial proliferation led to a decrease in the microenvironment pH value, resulting in the hydrolysis of the acid-sensitive Schiff base bonds, thereby releasing GS on demand and effectively enhancing the anti-biofilm properties of coatings. Benefiting from this synergistic antifouling and smart antibacterial activities, the PSB/GS coating exerted an excellent anti-infective activity in both in vivo preoperative and postoperative infection rat models. This proposed facile yet effective coating strategy is expected to provide a promising solution to combat bone implant-related infections.

Effect of mPEG-PLGA on Drug Crystallinity and Release of Long-Acting Injection Microspheres: In Vitro and In Vivo Perspectives.

PURPOSE: Traditional progesterone (PRG) injections require long-term administration, leading to poor patient compliance. The emergence of long-acting injectable microspheres extends the release period to several days or even months. However, these microspheres often face challenges such as burst release and incomplete drug release. This study aims to regulate drug release by altering the crystallinity of the drug during the release process from the microspheres. METHODS: This research incorporates methoxy poly(ethylene glycol)-b-poly(lactide-co-glycolide) (mPEG-PLGA) into poly(lactide-co-glycolide) (PLGA) microspheres to enhance their hydrophilicity, thus regulating the release rate and drug morphology during release. This modification aims to address the issues of burst and incomplete release in traditional PLGA microspheres. PRG was used as the model drug. PRG/mPEG-PLGA/PLGA microspheres (PmPPMs) were prepared via an emulsification-solvent evaporation method. Scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), and differential scanning calorimetry (DSC) were employed to investigate the presence of PRG in PmPPMs and its physical state changes during release. RESULTS: The addition of mPEG-PLGA altered the crystallinity of the drug within the microspheres at different release stages. The crystallinity correlated positively with the amount of mPEG-PLGA incorporated; the greater the amount, the faster the drug release from the formulation. The bioavailability and muscular irritation of the long-acting injectable were assessed through pharmacokinetic and muscle irritation studies in Sprague-Dawley (SD) rats. The results indicated that PmPPMs containing mPEG-PLGA achieved low burst release and sustained release over 7 days, with minimal irritation and self-healing within this period. PmPPMs with 5% mPEG-PLGA showed a relative bioavailability (Frel) of 146.88%. IN CONCLUSION: In summary, adding an appropriate amount of mPEG to PLGA microspheres can alter the drug release process and enhance bioavailability.

Co-delivery of Brinzolamide and Timolol from Micelles-laden Contact Lenses: In vitro and In Vivo Evaluation.

PURPOSE: Traditional eye drops exhibit a modest bioavailability ranging from 1 to 5%, necessitating recurrent application. Thus, a contact lens-based drug delivery system presents substantial benefits. Nonetheless, pharmaceutical agents exhibiting poor solubility may compromise the quintessential characteristics of contact lenses and are, consequently, deemed unsuitable for incorporation. To address this issue, the present study has engineered a novel composite drug delivery system that amalgamates micellar technology with contact lenses, designed specifically for the efficacious conveyance of timolol and brinzolamide. METHODS: Utilizing mPEG-PCL as the micellar material, this study crafted mPEG-PCL micelles loaded with brinzolamide and timolol through the film hydration technique. The micelle-loaded contact lens was fabricated employing the casting method; a uniform mixture of HEMA and EGDMA with the mPEG-PCL micelles enshrouding brinzolamide and timolol was synthesized. Following the addition of a photoinitiator, 50 µL of the concoction was deposited into a contact lens mold. Subsequently, the assembly was subjected to polymerization under 365 nm ultraviolet light for 35 min, resulting in the formation of the micelle-loaded contact lenses. RESULTS: In the present article, we delineate the construction of a micelle-loaded contact lens designed for the administration of brinzolamide and timolol in the treatment of glaucoma. The study characterizes crucial properties of the micelle-loaded contact lenses, such as transmittance and ionic permeability. It was observed that these vital attributes meet the standard requirements for contact lenses. In vitro release studies revealed that timolol and brinzolamide could be gradually liberated over periods of up to 72 and 84 h, respectively. In vivo pharmacodynamic evaluation showed a significant reduction in intraocular pressure and a relative bioavailability of 10.84 times that of commercially available eye drops. In vivo pharmacokinetic evaluation, MRT was significantly increased, and the bioavailability of timolol and brinzolamide was 2.71 and 1.41 times that of eye drops, respectively. Safety assessments, including in vivo irritation, histopathological sections, and protein adsorption studies, were conducted as per established protocols, confirming that the experiments were in compliance with safety standards. IN CONCLUSION: The manuscript delineates the development of a safe and efficacious micelle-loaded contact lens drug delivery system, which presents a novel therapeutic alternative for the management of glaucoma.

Sprayable Zwitterionic Antibacterial Hydrogel With High Mechanical Resilience and Robust Adhesion for Joint Wound Treatment.

Wound healing in movable parts, including the joints and neck, remains a critical challenge due to frequent motions and poor flexibility of dressings, which may lead to mismatching of mechanical properties and poor fitting between dressings and wounds; thus, increasing the risk of bacterial infection. This study proposes a sprayable zwitterionic antibacterial hydrogel with outstanding flexibility and desirable adhesion. This hydrogel precursor is fabricated by combining zwitterionic sulfobetaine methacrylate (SBMA) with poly(sulfobetaine methacrylate-co-dopamine methacrylamide)-modified silver nanoparticles (PSBDA@AgNPs) through robust electrostatic interactions. About 150 s of exposure to UV light, the SBMA monomer polymerizes to form PSB chains entangled with PSBDA@AgNPs, transformed into a stable and adhesion PSB-PSB@Ag hydrogel at the wound site. The resulting hydrogel has adhesive strength (15-38 kPa), large tensile strain (>400%), suitable shape adaptation, and excellent mechanical resilience. Moreover, the hydrogel displays pH-responsive behavior; the acidic microenvironment at the infected wound sites prompts the hydrogel to rapidly release AgNPs and kill bacteria. Further, the healing effect of the hydrogel is demonstrated on the rat neck skin wound, showing improved wound closing rate due to reduced inflammation and enhanced angiogenesis. Overall, the sprayable zwitterionic antibacterial hydrogel has significant potential to promote joint skin wound healing.

Injectable hydrogel with antimicrobial and anti-inflammatory properties for postoperative tumor wound care.

Clinically, tumor removal surgery leaves irregularly shaped wounds that are susceptible to bacterial infection and further lead to excessive inflammation. Injectable hydrogel dressings with antimicrobial and anti-inflammatory properties have been recognized as an effective strategy to care for postoperative tumor wounds and prevent recurrence in recent years. In this work, we constructed a hydrogel network by ionic bonding interactions between quaternized chitosan (QCS) and epigallocatechin gallate (EGCG)-Zn complexes which were coordinated by EGCG and zinc ions. Because of the synergistic effect of QCS and EGCG-Zn, the hydrogel exhibited outstanding antimicrobial capacity (>99.9% inhibition), which could prevent infections caused byEscherichia coli and Staphylococcus aureus. In addition, the hydrogel was able to inhibit the growth of mice breast cancer cells (56.81% survival rate within 72 h) and reduce inflammation, which was attributed to the sustained release of EGCG. The results showed that the hydrogel was effective in inhibiting tumor recurrence and accelerating wound closure when applied to the postoperative tumor wounds. This study provided a simple and reliable strategy for postoperative tumor wound care using antimicrobial and anti-inflammatory injectable dressings, confirming their great potential in the field of postoperative wound dressings.