Photodynamic chitosan sponges with dual instant and enduring bactericidal potency for treating skin abscesses

Facile preparation of fatigue-resistant Mxene-reinforced chitosan cryogel for accelerated hemostasis and wound healing

The development of highly effective chitosan-based hemostatic materials that can be utilized for deep wound hemostasis remains a considerable challenge. In this study, a hemostatic antibacterial chitosan/N-hydroxyethyl acrylamide (NHEMAA)/Ti3C2Tx (CSNT) composite cryogel was facilely prepared through the physical interactions between the three components and the spontaneous condensation of NHEMAA. Because of the formation of strong crosslinked network, the CSNT cryogel showed a developed pore structure (~ 99.07 %) and superfast water/blood-triggered shape recovery, enabling it to fill the wound after contacting the blood. Its capillary effect, amino groups, negative charges, and affinity with lipid collectively induced rapid hemostasis, which was confirmed by in vitro and in vivo analysis. In addition, CSNT cryogel showed excellent photothermal antibacterial activities, high biosafety, and in vivo wound healing ability. Furthermore, the presence of chitosan effectively prevented the oxidation of MXene, thus enabling the long-term storage of the MXene-reinforced cryogel. Thus, our hemostatic cryogel demonstrates promising potential for clinical application and commercialization, as it combines high resilience, rapid hemostasis, efficient sterilization, long-term storage, and easy mass production.

A hyaluronic acid hydrogel as a mild photothermal antibacterial, antioxidant, and nitric oxide release platform for diabetic wound healing

Hyaluronic acid (HA)-based biopolymer hydrogels are promising therapeutic dressings for various wounds but still underperform in treating diabetic wounds. These wounds are extremely difficult to heal and undergo a prolonged and severe inflammatory process due to bacterial infection, overexpression of reactive oxygen species (ROS), and insufficient synthesis of NO. In this study, a dynamic crosslinked hyaluronic acid (HA) hydrogel dressing (Gel-HAB) loaded with allomelanin (AMNP)-N, N'-dis-sec-butyl-N, N'-dinitroso-1, 4-phenylenediamine (BNN6) nanoparticles (AMNP-BNN6) was developed for healing diabetic wounds. The dynamic acylhydrazone bond formed between hydrazide-modified HA (HA-ADH) and oxidized HA (OHA) makes the hydrogel injectable, self-healing, and biocompatible. The hydrogel, loaded with AMNP-BNN6 nanoparticles, exhibits promising ROS scavenging ability and on-demand release of nitric oxide (NO) under near-infrared (NIR) laser irradiation to achieve mild photothermal antibacterial therapy (PTAT) (∼ 48 °C). Notably, the Gel-HAB hydrogel effectively reduced the oxidative stress level, controlled infections, accelerated vascular regeneration, and promoted angiogenesis, thereby achieving rapid healing of diabetic wounds. The injectable self-healing nanocomposite hydrogel could serve as a mild photothermal-enhanced antibacterial, antioxidant, and nitric oxide release platform for the treatment of diabetic wounds.

Ternary heterostructure-driven photoinduced electron-hole separation enhanced oxidative stress for triple-negative breast cancer therapy

Zinc oxide nanoparticles (ZnO NPs) stand as among the most significant metal oxide nanoparticles in trigger the formation of reactive oxygen species (ROS) and induce apoptosis. Nevertheless, the utilization of ZnO NPs has been limited by the shallowness of short-wavelength light and the constrained production of ROS. To overcome these limitations, a strategy involves achieving a red shift towards the near-infrared (NIR) light spectrum, promoting the separation and restraining the recombination of electron-hole (e--h+) pairs. Herein, the hybrid plasmonic system Au@ZnO (AZ) with graphene quantum dots (GQDs) doping (AZG) nano heterostructures is rationally designed for optimal NIR-driven cancer treatment. Significantly, a multifold increase in ROS generation can be achieved through the following creative initiatives: (i) plasmonic Au nanorods expands the photocatalytic capabilities of AZG into the NIR domain, offering a foundation for NIR-induced ROS generation for clinical utilization; (ii) elaborate design of mesoporous core-shell AZ structures facilitates the redistribution of electron-hole pairs; (iii) the incorporation GQDs in mesoporous structure could efficiently restrain the recombination of the e--h+ pairs; (iv) Modification of hyaluronic acid (HA) can enhance CD44 receptor mediated targeted triple-negative breast cancer (TNBC). In addition, the introduced Au NRs present as catalysts for enhancing photothermal therapy (PTT), effectively inducing apoptosis in tumor cells. The resulting HA-modified AZG (AZGH) exhibits efficient hot electron injection and e--h+ separation, affording unparalleled convenience for ROS production and enabling NIR-induced PDT for the cancer treanment. As a result, our well-designed mesoporous core-shell AZGH hybrid as photosensitizers can exhibit excellent PDT efficacy.

Functional nanomaterials as photosensitizers or delivery systems for antibacterial photodynamic therapy

Bacterial infection is a global health problem that closely related to various diseases threatening human life. Although antibiotic therapy has been the mainstream treatment method for various bacterial infectious diseases for decades, the increasing emergence of bacterial drug resistance has brought enormous challenges to the application of antibiotics. Therefore, developing novel antibacterial strategies is of great importance. By producing reactive oxygen species (ROS) with photosensitizers (PSs) under light irradiation, antibacterial photodynamic therapy (aPDT) has emerged as a non-invasive and promising approach for treating bacterial infections without causing drug resistance. However, the insufficient therapeutic penetration, poor hydrophilicity, and poor biocompatibility of traditional PSs greatly limit the efficacy of aPDT. Recently, studies have found that nanomaterials with characteristics of favorable photocatalytic activity, surface plasmonic resonance, easy modification, and high drug loading capacity can improve the therapeutic efficacy of aPDT. In this review, we aim to provide a comprehensive understanding of the mechanism of nanomaterials-mediated aPDT and summarize the representative nanomaterials in aPDT, either as PSs or carriers for PSs. In addition, the combination of advanced nanomaterials-mediated aPDT with other therapies, including targeted therapy, gas therapy, and multidrug resistance (MDR) therapy, is reviewed. Also, the concerns and possible solutions of nanomaterials-based aPDT are discussed. Overall, this review may provide theoretical basis and inspiration for the development of nanomaterials-based aPDT.

High-Density Dynamic Bonds Cross-Linked Hydrogel with Tissue Adhesion, Highly Efficient Self-Healing Behavior, and NIR Photothermal Antibacterial Ability as Dressing for Wound Repair

Multifunctional hydrogels with tissue adhesion, self-healing behavior, and antibacterial properties have potential in wound healing applications. However, their inefficient self-healing behavior and antibacterial agents can cause long-term cytotoxicity and drug resistance, considerably limiting their clinical use. Herein, we reported a PDA@LA hydrogel constructed by introducing polydopamine nanoparticles (PDA-NPs) into a high-density dynamic bonds cross-linked lipoic acid (LA) hydrogel that was formed by the polymerization of LA. Because of its rich carboxyl groups, the LA hydrogel could adhere firmly to various tissues. Owing to the high-density dynamic bonds, the cut LA hydrogel exhibited highly inefficient self-healing behavior and recovered to its uncut state after self-healing for 10 min. After the introduction of the PDA-NPs, the hydrogel was able to heat up to more than 40 °C to kill approximately 100% of the Escherichia coli and Staphylococcus aureus under near-infrared (NIR) laser, thus resisting wound infections. Because no toxic antibacterial agent was used, the PDA@LA hydrogel caused mild long-term cytotoxicity or drug resistance. Consequently, the adhesive, highly efficient self-healing, and NIR photothermal antibacterial PDA@LA hydrogel exhibits considerable potential for clinical use.

Cellulose nanofibers embedded chitosan/tannin hydrogel with high antibacterial activity and hemostatic ability for drug-resistant bacterial infected wound healing

Millions of patients annually suffer life-threatening illnesses caused by bacterial infections of skin wounds. However, the treatment of wounds infected with bacteria is a thorny issue in clinical medicine, especially with drug-resistant bacteria infections. Therefore, there is an increasing interest in developing wound dressings that can efficiently fight against drug-resistant bacterial infections and promote wound healing. In this work, an anti-drug-resistant bacterial chitosan/cellulose nanofiber/tannic acid (CS/CNF/TA) hydrogel with excellent wound management ability was developed by electrospinning and fiber breakage-recombination. The hydrogel exhibited an outstanding antibacterial property exceeding 99.9 %, even for drug-resistant bacteria. This hydrogel could adhere to the tissue surface due to its abundant catechol groups, which avoided the shedding of hydrogel during the movement. Besides, it exhibited extraordinary hemostatic ability during the bleeding phase of the wound and then regulated the wound microenvironment by absorbing water and moisturizing. Moreover, the CS/CNF/TA also promoted the regrowth of vessels and follicles, accelerating the healing of infected wound tissue, with a healing rate exceeding 95 % within a 14-day timeframe. Therefore, the CS/CNF/TA hydrogel opens a new approach for the healing of drug-resistant bacterial infected wounds.

Advances in chitosan and chitosan derivatives for biomedical applications in tissue engineering: An updated review

In recent years, chitosan (CS) has received much attention as a functional biopolymer for various applications, especially in the biomedical field. It is a natural polysaccharide created by the chemical deacetylation of chitin (CT) that is nontoxic, biocompatible, and biodegradable. This natural polymer is difficult to process; however, chemical modification of the CS backbone allows improved use of functional derivatives. CS and its derivatives are used to prepare hydrogels, membranes, scaffolds, fibers, foams, and sponges, primarily for regenerative medicine. Tissue engineering (TE), currently one of the fastest-growing fields in the life sciences, primarily aims to restore or replace lost or damaged organs and tissues using supports that, combined with cells and biomolecules, generate new tissue. In this sense, the growing interest in the application of biomaterials based on CS and some of its derivatives is justifiable. This review aims to summarize the most important recent advances in developing biomaterials based on CS and its derivatives and to study their synthesis, characterization, and applications in the biomedical field, especially in the TE area.

A Versatile Chitosan-Based Hydrogel Accelerates Infected Wound Healing via Bacterial Elimination, Antioxidation, Immunoregulation, and Angiogenesis

Drug-resistant bacterial infection of cutaneous wounds causes great harm to the human body. These infections are characterized by a microenvironment with recalcitrant bacterial infections, persistent oxidative stress, imbalance of immune regulation, and suboptimal angiogenesis. Treatment strategies available to date are incapable of handling the healing dynamics of infected wounds. A Schiff base and borate ester cross-linked hydrogel, based on phenylboronic acid-grafted chitosan (CS-PBA), dibenzaldehyde-grafted poly(ethylene glycol), and tannic acid (TA), is fabricated in the present study. Customized phenylboronic acid-modified zinc oxide nanoparticles (ZnO) are embedded in the hydrogel prior to gelation. The CPP@ZnO-P-TA hydrogel effectively eliminates methicillin-resistant Staphylococcus aureus (MRSA) due to the pH-responsive release of Zn2+ and TA. Killing is achieved via membrane damage, adenosine triphosphate reduction, leakage of intracellular components, and hydrolysis of bacterial o-nitrophenyl-β-d-galactopyranoside. The CPP@ZnO-P-TA hydrogel is capable of scavenging reactive oxygen and nitrogen species, alleviating oxidative stress, and stimulating M2 polarization of macrophages. The released Zn2+ and TA also induce neovascularization via the PI3K/Akt pathway. The CPP@ZnO-P-TA hydrogel improves tissue regeneration in vivo by alleviating inflammatory responses, stimulating angiogenesis, and facilitating collagen deposition. These findings suggest that this versatile hydrogel possesses therapeutic potential for the treatment of MRSA-infected cutaneous wounds.