Rational Design of PMPC/PDMC/PEGDA Hydrogel Micropatterns onto Polylactic Acid with Enhanced Biological Activity

The Optimization of Culture Conditions for Injectable Recombinant Collagen Hydrogel Preparation Using Machine Learning

Injectable recombinant collagen hydrogels (RCHs) are crucial in biomedical applications. Culture conditions play an important role in the preparation of hydrogels. However, determining the characteristics of hydrogels under certain conditions and determining the optimal conditions swiftly still remain challenging tasks. In this study, a machine learning approach was introduced to explore the correlation between hydrogel characteristics and culture conditions and determine the optimal culture conditions. The study focused on four key factors as independent variables: initial substrate concentration, reaction temperature, pH level, and reaction time, while the dependent variable was the elastic modulus of the hydrogels. To analyze the impact of these factors on the elastic modulus, four mathematical models were employed, including multiple linear regression (ML), decision tree (DT), support vector machine (SVM), and neural network (NN). The theoretical outputs of NN were closest to the actual values. Therefore, NN proved to be the most suitable model. Subsequently, the optimal culture conditions were identified as a substrate concentration of 15% (W/V), a reaction temperature of 4 °C, a pH of 7.0, and a reaction time of 12 h. The hydrogels prepared under these specific conditions exhibited a predicted elastic modulus of 15,340 Pa, approaching that of natural elastic cartilage.

Tailored chitosan/glycerol micropatterned composite dressings by 3D printing for improved wound healing

Wound infection control is a primary clinical concern nowadays. Various innovative solutions have been developed to fabricate adaptable wound dressings with better control of infected wound healing. This work presents a facile approach by leveraging 3D printing to fabricate chitosan/glycerol into composite dressings with tailored micropatterns to improve wound healing. The bioinks of chitosan/glycerol were investigated as suitable for 3D printing. Then, three tailored micropatterns (i.e., sheet, strip, and mesh) with precise geometry control were 3D printed onto a commercial dressing to fabricate the micropatterned composite dressings. In vitro and in vivo studies indicate that these micropatterned dressings could speed up wound healing due to their increased water uptake capacity (up to ca. 16-fold@2 min), benign cytotoxicity (76.7 % to 90.4 % of cell viability), minor hemolytic activity (<1 %), faster blood coagulation effects (within 76.3 s), low blood coagulation index (14.5 % to 18.7 % @ 6 min), enhanced antibacterial properties (81.0 % to 86.1 % against S. aureus, 83.7 % to 96.5 % against E. coli), and effective inhibition of wound inflammation factors of IL-1β and TNF-α. Such tailored micropatterned composite dressing is facile to obtain, highly reproducible, and cost-efficient, making it a promising implication for improved and personalized contaminated wound healing.

In Situ Forming Hydrogel as a Tracer and Degradable Lacrimal Plug for Dry Eye Treatment

Lacrimal plug is an effective and widely therapeutic strategy to treat dry eye. However, almost all commercialized plugs are fixed in a certain design and associated with many complications, such as spontaneous plug extrusion, epiphora, and granuloma and cannot be traced in the long-term. Herein, a simple in situ forming hydrogel is developed as a tracer and degradable lacrimal plug to achieve the best match with the irregular lacrimal passages. In this strategy, methacrylate-modified silk fibroin (SFMA) is served as a network, and a self-assembled indocyanine green fluorescence tracer nanoparticle (FTN) is embedded as an indicator to develop the hydrogel plug using visible photo-crosslinking. This SFMA/FTN hydrogel plug has excellent biocompatibility and biodegradability, which can be noninvasively monitored by near-infrared light. In vivo tests based on dry eye rabbits show that the SFMA/FTN hydrogel plug can completely block the lacrimal passages and greatly improve the various clinical indicators of dry eye. These results demonstrate that the SFMA/FTN hydrogel is suitable as an injectable and degradable lacrimal plug with a long-term tracking function. The work offers a new approach to the development of absorbable plugs for the treatment of dry eye.

Highly Permeable Polylactic Acid Membrane Grafted with Quaternary Ammonium Salt for Effective and Durable Water Disinfection

Given the increasing usage of drinking water purifiers, highly permeable membranes with strong antimicrobial functions are desperately desirable for effective and durable water disinfection. Hereby, we prepared such antimicrobial membranes by chemical grafting of quaternary ammonium salt (QAS) molecules, 3-(trimethoxysilyl)propyldimethyloctadecyl ammonium chloride (TPMMC), onto air plasma pretreated biodegradable polylactic acid (PLA) substrates. The high chemical grafting density promoted very strong and positive zeta potential charge of the resulted PLA-QAS membrane, contributing to effective and broad-spectrum antimicrobial efficiencies (>99.99%) against different microbes, including fungi and conventional and drug-resistant bacteria. The solid grafting of QAS molecules produced a durable antimicrobial performance of the PLA-QAS membrane. In addition, the pleated filter (0.45 m²) of PLA-QAS membrane showed outstanding bacteria rejection properties (>99.99%) and excellent washing durability (up to 20 m³ water) even at very high water filtration rates (up to 4 L/min). The disinfection mechanism was clarified that negatively charged bacteria could be rapidly adsorbed to positively charged PLA-QAS spinnings, followed by devastating cell membrane damage to bacterial debris, leaving a clean environment without significant biofilm and biofouling formation.