Amphiphilic sodium alginate-polylysine hydrogel with high antibacterial efficiency in a wide pH range

Photothermally Responsive Hydrogel Releases Basic Fibroblast Growth Factor to Promote the Healing of Infected Wounds

The treatment of infected wounds is often complicated by bacterial infection and impaired scar healing. Antibiotics and growth factors are typically utilized to address these clinical challenges and expedite wound healing. However, the use of hydrogels containing these therapeutic agents is often restricted to complex cases and increases treatment costs considerably. In this study, we developed a quaternized-chitosan-based hybrid hydrogel dressing (SQFB) with intrinsic antibacterial properties to address these limitations. The hybrid hydrogel contained interpenetrating polymer networks of basic fibroblast growth factor and black phosphorus nanosheets, facilitating a photothermal response that triggers the release of basic fibroblast growth factor upon near-infrared irradiation. In vitro experiments demonstrated that SQFB exhibits superior antibacterial, hemostatic, enhanced cell proliferation, and angiogenesis functions. Importantly, the results showed that SQFB can promote the healing of infected wounds by accelerating all 4 stages of wound repair while preventing scarring formation. RNA sequencing analysis revealed that combined treatment with SQFB and near-infrared irradiation can effectively modulate genes primarily associated with epithelial regeneration pathways and metabolic processes. Collectively, our findings suggest that this hybrid hydrogel holds great promise for the effective management of infected wounds.

Injectable polyethylene glycol/methacrylated polylysine double cross-linked hydrogel releases neuropeptides for infected wound healing

Wound infections caused by microorganisms often give rise to extensive inflammation and vascular damage that compromise the wound healing process. Designing approaches to more effectively controlling wound infections and accelerating this healing process are urgently needed. This study was designed with the goal of synthesizing an injectable, double cross-linked hydrogel suitable for use when treating infected wounds. After initially synthesizing methacrylated polylysine (PLMA) through polylysine grafting with methacrylic anhydride, CGRP and PLMA were incorporated into a PEG hydrogel network through reactions between NHS-activated carboxyl esters and amino groups (NH₂). PLMA was also employed to enhance the self-crosslinking activity, culminating in the production of PEG/PLMA/CGRP double cross-linked hydrogels. After injection these hydrogels were capable of undergoing rapid molding such that they were able to conform to the irregularly shaped wound contours. This PEG/PLMA/CGRP formulation was capable of mimicking nerve ending-mediated CGRP secretion to control wound healing, while also exhibiting robust antioxidant, anti-inflammatory, and pro-angiogenic properties. In addition, PEG/PLMA/CGRP hydrogels in vitro showed robust resistance to S. aureus and E. coli. In a rat model of S. aureus-mediated wound infection, this hydrogel markedly promoted wound healing. PEG/PLMA/CGRP hydrogels are thus an effective tool for use in the context of infected wound healing.

Self-adhesive poly-l-lysine/tannic acid hybrid hydrogel for synergistic antibacterial activity against biofilms

Biomedical implants are crucial for enhancing various human physiological functions. However, they are susceptible to microbial contamination after implantation, posing a risk of implant failure. To address this issue, hydrogel-based coatings are used, but achieving both effective antibacterial properties and stable adhesion remains challenging. This study introduces a hybrid hydrogel network made from Tannic Acid (TA) and Poly-l-Lysine (PLL), cross-linked through ionic and hydrogen bonds, which imparts adhesive and anti-infective properties. The physicochemical analysis revealed that the hydrogels exhibited significant porosity, favorable mechanical characteristics, and demonstrated in vitro enzymatic biodegradation. Moreover, the hydrogels demonstrated adhesion to various substrates, including Ti alloy with an adhesive strength of 42.5 kPa, and retained their integrity even after immersion in water for a minimum of 10 days. The modified Ti surfaces significantly reduced protein adsorption (∼70 %), indicating antifouling properties. The hydrogels prevented bacterial adhesion on titanium surfaces through a "contact-kill" mode of action and inhibited biofilm formation by around 94.5 % for Staphylococcus aureus and 90.8 % for Pseudomonas aeruginosa. The modified Ti retained biofilm inhibitory effects for at least six days without significant performance decline. In vitro cytotoxicity assay confirmed the biocompatibility of the hydrogels with NIH3T3 cells. Overall, these results highlight the competence of hybrid hydrogels as effective coatings for Ti implants, offering strong adhesion and biofilm prevention to mitigate implant-related infections.

Microbead-Encapsulated Luminescent Bioreporter Screening of P. aeruginosa via Its Secreted Quorum-Sensing Molecules

Pseudomonas aeruginosa is an opportunistic Gram-negative bacterium that remains a prevalent clinical and environmental challenge. Quorum-sensing (QS) molecules are effective biomarkers in pinpointing the presence of P. aeruginosa. This study aimed to develop a convenient-to-use, whole-cell biosensor using P. aeruginosa reporters individually encapsulated within alginate-poly-L-lysine (alginate-PLL) microbeads to specifically detect the presence of bacterial autoinducers. The PLL-reinforced microbeads were prepared using a two-step method involving ionic cross-linking and subsequent coating with thin layers of PLL. The alginate-PLL beads showed good stability in the presence of a known cation scavenger (sodium citrate), which typically limits the widespread applications of calcium alginate. In media containing synthetic autoinducers-such as N-(3-oxo dodecanoyl) homoserine lactone (3-oxo-C12-HSL) and N-butanoyl-L-homoserine lactone (C4-HSL), or the cell-free supernatants of planktonic or the flow-cell biofilm effluent of wild P. aeruginosa (PAO1)-the encapsulated bacteria enabled a dose-dependent detection of the presence of these QS molecules. The prepared bioreporter beads remained stable during prolonged storage at 4 and -80 °C and were ready for on-the-spot sensing without the need for recovery. The proof-of-concept, optical fiber-based, and whole-cell biosensor developed here demonstrates the practicality of the encapsulated bioreporter for bacterial detection based on specific QS molecules.

Advanced-design cross-linked binder enables high-performance silicon-based anodes through in-situ crosslinking based on sodium carboxymethyl cellulose and poly-lysine

Practical employment of silicon (Si) electrodes in lithium-ion batteries (LIBs) is limited due to the severe volume changes suffered during charging-discharging process, causing serious capacity fading. Here, a composite polymer (CP-10) containing sodium carboxymethyl cellulose (CMC-Na) and poly-lysine (PL) is proposed for the binder of Si-based anodes, and a multifunctional strategy of "in-situ crosslinking" is achieved to alleviate the severe capacity degradation effectively. A cross-linked three-dimensional (3D) network is established through the strong hydrogen bonding interaction and reversible electrostatic interactions within CP-10, offering favorable mechanical tolerance for the extreme volume expansion of Si. Moreover, hydrogen bonding interaction along with ion-dipole interaction formed between CP-10 and Si surface enhance the bonding capability of Si-based anodes, promoting the maintenance of anodes' integrity. Consequently, over 800 cycles are achieved for the Si@CP-10 at 0.5C while maintaining a fixed discharge specific capacity of 1000 mAh g-1. Moreover, the Si/C@CP-10 can stably operate over 500 cycles with a capacity retention of 77.12 % at 1C. The prolonged cycling lifetime of Si/C and Si anodes suggests great potential for this strategy in promoting the implementation of high-capacity LIBs.

Design and characterization of tannic acid/ε-polylysine biocomposite packaging films with excellent antibacterial and antioxidant properties for beef preservation

The shelf life of beef is shortened by microbial infection, which limits its supply in the market. Active packaging film is expected to overcome this difficulty. In this study, an antibacterial/antioxidant SS-ε-PL-TA biocomposite film made by soy protein isolate/sodium alginate/ε-polylysine/tannic acid was designed and prepared. Due to the formation of hydrogen bonds and enhanced hydrophobic interactions, the biocomposite film showed enhanced mechanical property. Tensile strength increased from 22.8 ± 2.59 MPa to 64.34 ± 6.22 MPa, and elongation at break increased from 7.70 ± 1.07 % to 13.98 ± 0.22 %. The composite film displayed excellent antibacterial activity owing to the damage to cell membranes and biofilms of bacteria. Furthermore, the antioxidant activity also significantly increased (DPPH ∙ scavenging activity was 78.0 %). The shelf life of beef covered with the SS-ε-PL-TA film was extended by 3 days compared to the control group by decreasing lipid oxidation and inhibiting bacterial growth, showing a good application potential in food packaging.

Current status of development and biomedical applications of peptide-based antimicrobial hydrogels

Microbial contamination poses a serious threat to human life and health. Through the intersection of material science and modern medicine, advanced bionic hydrogels have shown great potential for biomedical applications due to their unique bioactivity and ability to mimic the extracellular matrix environment. In particular, as a promising antimicrobial material, the synthesis and practical biomedical applications of peptide-based antimicrobial hydrogels have drawn increasing research interest. The synergistic effect of peptides and hydrogels facilitate the controlled release of antimicrobial agents and mitigation of their biotoxicity while achieving antimicrobial effects and protecting the active agents from degradation. This review reports on the progress and trends of researches in the last five years and provides a brief outlook, aiming to provide theoretical background on peptide-based antimicrobial hydrogels and make suggestions for future related work.

Mussel-inspired "all-in-one" sodium alginate/carboxymethyl chitosan hydrogel patch promotes healing of infected wound

Hydrogels have been widely used as wound dressings to accelerate wound healing. However, due to the impaired skin barrier at the wound site, external bacteria can easily invade the wound and cause infection. In this study, we designed a dopamine-modified sodium alginate/carboxymethyl chitosan/polyvinylpyrrolidone (CPD) hydrogel, which was able to promote wound healing while preventing wound infection. Due to the high content of catechol groups, the CPD hydrogel exhibited good tissue adhesion ability and a significant scavenging ability for DPPH• and PTIO• radicals. Under near-infrared laser irradiation, the temperature of CPD hydrogel increased significantly, which significantly killed the Staphylococcus aureus and Escherichia coli. The cell migration test confirmed that CPD hydrogel could promote the cell migration ratio. In the in vivo wound healing test for infected full-thickness skin defect, CPD hydrogel significantly inhibited bacterial proliferation and enhanced wound healing rate. Therefore, the multifunctional hydrogel is expected to be applied to wound healing.

Double-network cellulose-based hybrid hydrogels with favourable biocompatibility and antibacterial activity for wound healing

Bacterial infections are among the leading causes of delayed wound healing. At present, a series of antibacterial materials, such as antibiotics, antimicrobial peptides (AMPs), metals and metal oxides (MMOs), have been used to fabricate antibacterial wound dressings. However, their translational potential is limited owing to their poor biocompatibility. ε-Polylysine (ε-PL) is a natural macromolecule with excellent biocompatibility and broad-spectrum antibacterial activity. Herein, ε-PL was incorporated into a cellulose/γ-polyglutamic acid (γ-PGA) composite hydrogel to form a novel double-network hydrogel termed as CGLH. The elastic modulus of CGLH increased from 0.097 ± 0.015 MPa to 0.441 ± 0.096 MPa, and the equilibrium swelling ratio increased from 382.7 ± 24.3 % to 611.2 ± 8.6 %. Several preclinical models were used to investigate the translational potential of this hydrogel. CGLH exhibited good biocompatibility and antibacterial activity, which promoted the healing of infected and critical-size wounds within 12 days. CGLH had positive effects on collagen synthesis, vascularization and cell proliferation. As a result, this study not only provided an effective alternative for wound healing but also proposed a double-network strategy for creating biocompatible and antibacterial biomaterials.

Recent Advances of Natural-Polymer-Based Hydrogels for Wound Antibacterial Therapeutics

Hydrogels have a three-dimensional network structure and high-water content, are similar in structure to the extracellular matrix, and are often used as wound dressings. Natural polymers have excellent biocompatibility and biodegradability and are commonly utilized to prepare hydrogels. Natural-polymer-based hydrogels can have excellent antibacterial and bioactive properties by loading antibacterial agents or being combined with therapeutics such as phototherapy, which has great advantages in the field of treatment of microbial infections. In the published reviews of hydrogels used in the treatment of infectious wounds, the common classification criteria of hydrogels include function, source of antibacterial properties, type of antibacterial agent, etc. However, there are few reviews on the classification of hydrogels based on raw materials, and the description of natural-polymer-based hydrogels is not comprehensive and detailed. In this paper, based on the principle of material classification, the characteristics of seven types of natural polymers that can be used to prepare hydrogels are discussed, respectively, and the application of natural-polymer-based hydrogels in the treatment of infectious wounds is described in detail. Finally, the research status, limitations, and prospects of natural-polymer-based hydrogels are briefly discussed.