Bilayer hydrogel dressing with lysozymeenhanced photothermal therapy for biofilm eradication and accelerated chronic wound repair

Biofilms are closely associated with the tough healing and dysfunctional inflammation of chronic wounds.Photothermal therapy(PTT)emerged as a suitable alternative which could destroy the structure of biofilms with local physical heat.However,the efficacy of PTT is limited because the excessive hyperthermia could damage surrounding tissues.Besides,the difficult reserve and delivery of photothermal agents makes PTT hard to eradicate biofilms as expectation.Herein,we present a GelMA-EGF/Gelatin-MPDA-LZM bilayer hydrogel dressing to perform lysozyme-enhanced PTT for biofilms eradication and a further acceleration to the repair of chronic wounds.Gelatin was used as inner layer hydrogel to reserve lysozyme(LZM)loaded mesoporous polydopamine(MPDA)(MPDA-LZM)nanoparticles,which could rapidly liquefy while temperature rising so as to achieve a bulk release of nanoparticles.MPDA-LZM nanoparticles serve as photothermal agents with antibacterial capability,could deeply penetrate and destroy biofilms.In addition,the outer layer hydrogel consisted of gelatin methacryloyl(GelMA)and epidermal growth factor(EGF)promoted wound healing and tissue regeneration.It displayed remarkable efficacy on alleviating infection and accelerating wound healing in vivo.Overall,the innovative therapeutic strategy we came up with has significant effect on biofilms eradication and shows promising application in promoting the repair of clinical chronic wounds.

Fabrication of Biomimetic Transparent and Flexible Pectin/PEG Composite Film for Temperature Sensing Applications

In the field of robotics to enhance the interaction with humans in real-time and in the bioengineering field to develop prosthetic devices, the need for artificial skin is in high demand. In this work, the hydrogen-bonded complex network structure of the Pectin/PEG composite has been designed, resulting in the free-standing film functioning as a temperature-sensing device. With the gelation technique and the addition of PEG, the film’s flexibility and conductivity were enhanced. The fabricated device worked at a low voltage of 1 V supply with high throughput. With different dimensions, three devices were fabricated, and the maximum-induced ionic current was 34 µA ± 5%. The device has an average sensitivity of 1.3–2.7 µA/°C over the range of 30 °C to 42 °C. The device's fastest response time to sense the temperature change was 2 s ± 5%. The present device exhibits good stability for a long duration of time. These pectin/PEG films can be used as biomimetic skin to improve the efficiency in sensing the temperature.

An Injectable Hydrogel with or without Drugs for Prevention of Epidural Scar Adhesion after Laminectomy in Rats

Epidural scarring occurs inevitably in the defect after spinal laminectomy, and thus how to prevent or reduce it becomes a challenging topic. In the present study, an injectable hydrogel and its dexamethasone （DEX）-loaded hydrogel systems were adopted to prevent epidural scarring in a postlaminectomy rat model. The hydrogel system composed of poly（D,L-lactic acid-co-glycolic acid）-poly（ethylene glycol）-poly（D,L-lactic acid-co-glycolic acid） （PLGA-PEG-PLGA） triblock copolymers was a free-flowing sol at room temperature, and spontaneously turned into a semi-solid gel at body temperature. A lumbar 3 total laminectomy was performed on Sprague Dawley （SD） rats, and the efficacy of the injectable hydrogel with or without drugs in preventing epidural scar formation was evaluated via the gross anatomical observation and histological examination at one month post-surgery. The results demonstrate that the use of hydrogel alone reduced epidural scarring significantly, whereas the efficacy of the DEX-loaded hydrogels presented an irregular dose-dependency of drug and even the inappropriate drug doses resulted in the negative results. Therefore, the present study confirms that the PLGA-PEG- PLGA hydrogel holds potential as a barrier device to decrease peridural scarring, and reveals that the sustained delivery of the steroid hormone DEX to prevent surgery-related adhesions in the laminectomy defect is complex. Moreover, our in vivo studies also remind the researchers to pay attention to the irregular dose-dependency of the hormone drugs.