Near-infrared light-controllable on-demand antibiotics release using thermo-sensitive hydrogel-based drug reservoir for combating bacterial infection

Photothermal enhanced antibacterial chitosan-based polydopamine composite hydrogel for hemostasis and burn wound repairing

Bleeding and bacterial infection are common problems associated with wound treatment, while effective blood clotting and vessel regeneration promotion are the primary considerations to design the wound dressing materials. This research presents a chitosan-based hydrogel with grafted quaternary ammonium and polyphosphate (QCSP hydrogel) as the antibacterial hemostatic dressing to achieve burn wound treatment. The tissue adhesion of the hydrogel sealed the blood flow and the polyphosphate grafted to the chitosan promoted the activation of coagulation factor V to enhance the hemostasis. At the same time, the grafted quaternary ammonium enhanced the antibacterial ability of the biodegradable hydrogel wound dressing. In addition, the polydopamine as a photothermal agent was composited into the hydrogel to enhance the antibacterial and reactive oxygen scavenging performance. The in vivo hemostasis experiment proved the polyphosphate enhanced the coagulation property. Moreover, this photothermal property of the composite hydrogel enhanced the burn wound repairing rate combined with the NIR stimulus. As a result, this hydrogel could have potential application in clinic as dressing material for hemostasis and infection prone would repairing.

Progress in chitin/chitosan and their derivatives for biomedical applications: Where we stand

Chitin and its deacetylated form, chitosan, have demonstrated remarkable versatility in the realm of biomaterials. Their exceptional biocompatibility, antibacterial properties, pro- and anticoagulant characteristics, robust antioxidant capacity, and anti-inflammatory potential make them highly sought-after in various applications. This review delves into the mechanisms underlying chitin/chitosan's biological activity and provides a comprehensive overview of their derivatives in fields such as tissue engineering, hemostasis, wound healing, drug delivery, and hemoperfusion. However, despite the wealth of studies on chitin/chitosan, there exists a notable trend of homogeneity in research, which could hinder the comprehensive development of these biomaterials. This review, taking a clinician's perspective, identifies current research gaps and medical challenges yet to be addressed, aiming to pave the way for a more sustainable future in chitin/chitosan research and application.

Iodine/soluble starch cryogel: An iodine-based antiseptic with instant water-solubility, improved stability, and potent bactericidal activity

Iodine (I2) as a broad-spectrum antiseptic has been widely used for treating bacterial infections. However, I2 has low water-solubility and sublimes under ambient conditions, which limits its practical antibacterial applications. The highly specific and sensitive reaction between I2 and starch discovered 200 years ago has been extensively applied in analytical chemistry, but the antibacterial activity of the I2-starch complex is rarely investigated. Herein, we develop a novel type of iodine-based antiseptics, iodine-soluble starch (I2-SS) cryogel, which can dissolve in water instantly and almost completely kill bacteria in 10 min at 2 μg/mL of I2. Although KI3 and the commercially available povidone‑iodine (I2-PVP) solutions show similar antibacterial efficacy, the high affinity of I2 to SS largely enhances the shelf stability of the I2-SS solution with ∼73 % I2 left after one-week storage at room temperature. In sharp contrast, ∼8.5 % and ∼2.5 % I2 are detected in KI3 and I2-PVP solutions, respectively. Mechanistic study reveals that the potent antibacterial effect of I2-SS originates from its attack on multiple bacterial targets. The outstanding antibacterial activity, capability of accelerating wound healing, and good biocompatibility of I2-SS are verified through further in vivo experiments. This work may promote the development of next-generation iodine-based antiseptics for clinical use.

Molybdenum disulfide nanosheets based non-oxygen-dependent and heat-initiated free radical nanogenerator with antimicrobial peptides for antimicrobial, biofilm ablation and wound healing

Chronic refractory wounds caused by multidrug-resistant (MDR) bacterial and biofilm infections are a substantial threat to human health, which presents a persistent challenge in managing clinical wound care. We here synthesized a composite nanosheet AIPH/AMP/MoS2, which can potentially be used for combined therapy because of the photothermal effect induced by MoS2, its ability to deliver antimicrobial peptides, and its ability to generate alkyl free radicals independent of oxygen. The synthesized nanosheets exhibited 61 % near-infrared (NIR) photothermal conversion efficiency, marked photothermal stability and free radical generating ability. The minimal inhibitory concentrations (MICs) of the composite nanosheets against MDR Escherichia coli (MDR E. coli) and MDR Staphylococcus aureus (MDR S. aureus) were approximately 38 μg/mL and 30 μg/mL, respectively. The composite nanosheets (150 μg/mL) effectively ablated >85 % of the bacterial biofilm under 808-nm NIR irradiation for 6 min. In the wound model experiment, approximately 90 % of the wound healed after the 4-day treatment with the composite nanosheets. The hemolysis experiment, mouse embryonic fibroblast (MEFs) cytotoxicity experiment, and mouse wound healing experiment all unveiled the excellent biocompatibility of the composite nanosheets. According to the transcriptome analysis, the composite nanosheets primarily exerted a synergistic therapeutic effect by disrupting the cellular membrane function of S. aureus and inhibiting quorum sensing mediated by the two-component system. Thus, the synthesized composite nanosheets exhibit remarkable antibacterial and biofilm ablation properties and therefore can be used to improve wound healing in chronic biofilm infections.

Mild Thermotherapy-Assisted GelMA/HA/MPDA@Roxadustat 3D-Printed Scaffolds with Combined Angiogenesis-Osteogenesis Functions for Bone Regeneration

Early reconstruction of the vascular network is a prerequisite to the effective treatment of substantial bone defects. Traditional 3D printed tissue engineering scaffolds designed to repair large bone defects do not effectively regenerate the vascular network, and rely only on the porous structure within the scaffold for nutrient transfer and metabolic waste removal. This leads to delayed bone restoration and hence functional recovery. Therefore, strategies for generation scaffolds with the capacity to efficiently regenerate vascularization should be developed. This study loads roxarestat (RD), which can stabilize HIF-1α expression in a normoxic environment, onto the mesopore polydopamine nanoparticles (MPDA@RD) to enhance the reconstruction of vascular network in large bone defects. Subsequently, MPDA@RD is mixed with GelMA/HA hydrogel bioink to fabricate a multifunctional hydrogel scaffold (GHM@RD) through 3D printing. In vitro results show that the GHM@RD scaffolds achieve good angiogenic-osteogenic coupling by activating the PI3K/AKT/HSP90 pathway in BMSCs and the PI3K/AKT/HIF-1α pathway in HUVECs under mild thermotherapy. In vivo experiments reveal that RD and mild hyperthermia synergistically induce early vascularization and bone regeneration of critical bone defects. In conclusion, the designed GHM@RD drug delivery scaffold with mild hyperthermia holds great therapeutic value for future treatment of large bone defects.

Preparation strategies of mussel-inspired chitosan-based biomaterials for hemostasis

Chitosan (CS) has been extensively studied in wound care for its intrinsic hemostatic and antibacterial properties. However, CS has limiting hemostasis applications on account of its drawbacks such as poor adhesion in humid environments and water solubility at neutral pH. CS-based biomaterials, inspired by mussel-adhesive proteins, serve as a suggested platform by biomedical science. The reports show that the mussel-inspired CS-based hemostatic structure has negligible toxicity and excellent adhesiveness. Biomedicine has witnessed significant progress in the development of these hemostatic materials. This review summarizes the methods for the modification of CS by mussel-inspired chemistry. Moreover, the general method for preparation of mussel-inspired CS-based biomaterials is briefly discussed in this review. This work is expected to give a better understanding of opportunities and challenges of the mussel-inspired strategy for the functionalization of CS-based biomaterials in hemostasis and wound healing. This review is hoped to provide an important perspective on the preparation of mussel-inspired CS-based hemostatic materials.

Polydopamine-Based Targeted Nanosystem for Chemo/Photothermal Therapy of Retinoblastoma in a Mouse Orthotopic Model

Background

At present, the few photothermal/chemotherapy studies about retinoblastoma that have been reported are mainly restricted to ectopic models involving subcutaneous implantation. However, eyeball is unique physiological structure, the blood-retina barrier (BRB) hinders the absorption of drug molecules through the systemic route. Moreover, the abundant blood circulation in the fundus accelerates drug metabolism. To uphold the required drug concentration, patients must undergo frequent chemotherapy sessions.

Purpose

To address these challenges above, we need to develop a secure and effective drug delivery system (FA-PEG-PDA-DOX) for the fundus.

Methods

We offered superior therapeutic efficacy with minimal or no side effects and successfully established orthotopic mouse models. We evaluated cellular uptake performance and targeting efficiency of FA-PEG-PDA-DOX nanosystem and assessed its synergistic antitumor effects in vitro and vivo. Biodistribution assessments were performed to determine the retention time and targeting efficiency of the NPs in vivo. Additionally, safety assessments were conducted.

Results

Cell endocytosis rates of the FA-PEG-PDA-DOX+Laser group became 5.23 times that of the DOX group and 2.28 times that of FA-PEG-PDA-DOX group without irradiation. The fluorescence signal of FA-PEG-PDA-DOX persisted for more than 120 hours at the tumor site. The number of tumor cells (17.2%) in the proliferative cycle decreased by 61.6% in the photothermal-chemotherapy group, in contrast to that of the saline control group (78.8%). FA-PEG-PDA-DOX nanoparticles(NPs) exhibited favorable biosafety and high biocompatibility.

Conclusion

The dual functional targeted nanosystem, with the effects of DOX and mild-temperature elevation by irradiation, resulted in precise chemo/photothermal therapy in nude mice model.

A New Nanoplatform Under NIR Released ROS Enhanced Photodynamic Therapy and Low Temperature Photothermal Therapy for Antibacterial and Wound Repair

Purpose

Skin injury, often caused by physical or medical mishaps, presents a significant challenge as wound healing is critical to restore skin integrity and tissue function. However, external factors such as infection and inflammation can hinder wound healing, highlighting the importance of developing biomaterials with antibiotic and wound healing properties to treat infections and inflammation. In this study, a novel photothermal nanomaterial (MMPI) was synthesized for infected wound healing by loading indocyanine green (ICG) on magnesium-incorporated mesoporous bioactive glass (Mg-MBG) and coating its surface with polydopamine (PDA).

Results

In this study, Mg-MBG and MMPI was synthesized via the sol-gel method and characterized it using various techniques such as scanning electron microscopy (SEM), the energy dispersive X-ray spectrometry (EDS) system and X-ray diffraction (XRD). The cytocompatibility of MMPI was evaluated by confocal laser scanning microscopy (CLSM), CCK8 assay, live/dead staining and F-actin staining of the cytoskeleton. The antibacterial efficiency was assessed using bacterial dead-acting staining, spread plate method (SPM) and TEM. The impact of MMPI on macrophage polarization was initially evaluated through flow cytometry, qPCR and ELISA. Additionally, an in vivo experiment was performed on a mouse model with skin excision infected. Histological analysis and RNA-seq analysis were utilized to analyze the in vivo wound healing and immunomodulation effect.

Conclusion

Collectively, the new photothermal and photodynamic nanomaterial (MMPI) can achieve low-temperature antibacterial activity while accelerating wound healing, holds broad application prospects.

Stimuli-Responsive Hydrogels Potentiating Photothermal Therapy against Cancer Stem Cell-Induced Breast Cancer Metastasis

The self-renewal and differentiation properties of cancer stem cells (CSCs) result in chemoresistance in breast cancer. Even though numerous drugs have been developed to target CSCs, they have suffered from inefficient delivery and accumulation at the focal site. Here, a thermoresponsive hydrogel is developed by coencapsulating aggregation-induced emission (AIE)-active photothermal agent and thioridazine (THZ), demonstrating a controllable delivery system triggered by the AIE agent to augment THZ-mediated CSC ablation. Upon near-infrared laser stimuli, the photothermal effect from the AIE agent induces hydrogel deformation for burst drug release. The precise in situ tumor administration of the hydrogel accelerates drug diffusion and accumulation in deep breast cancer lesions. Thus, THZ can invade tumors and provoke massive CSC apoptosis via dopamine receptor blockage and oxidative stress induction. Consequently, effective CSC inhibition and significant suppression of tumor recurrence and metastasis are demonstrated in mice with breast cancer. We believe that this intelligent hydrogel-based delivery system represents a promising treatment strategy for metastatic breast cancer with clinical potential.

Tailor-Made Polysaccharides for Biomedical Applications

Polysaccharides (PSAs) are carbohydrate-based macromolecules widely used in the biomedical field, either in their pure form or in blends/nanocomposites with other materials. The relationship between structure, properties, and functions has inspired scientists to design multifunctional PSAs for various biomedical applications by incorporating unique molecular structures and targeted bulk properties. Multiple strategies, such as conjugation, grafting, cross-linking, and functionalization, have been explored to control their mechanical properties, electrical conductivity, hydrophilicity, degradability, rheological features, and stimuli-responsiveness. For instance, custom-made PSAs are known for their worldwide biomedical applications in tissue engineering, drug/gene delivery, and regenerative medicine. Furthermore, the remarkable advancements in supramolecular engineering and chemistry have paved the way for mission-oriented biomaterial synthesis and the fabrication of customized biomaterials. These materials can synergistically combine the benefits of biology and chemistry to tackle important biomedical questions. Herein, we categorize and summarize PSAs based on their synthesis methods, and explore the main strategies used to customize their chemical structures. We then highlight various properties of PSAs using practical examples. Lastly, we thoroughly describe the biomedical applications of tailor-made PSAs, along with their current existing challenges and potential future directions.

Dental Caries Management with Antibacterial Silver-Doped Prussian Blue Hydrogel by the Combined Effects of Photothermal Response and Ion Discharge

Caries is a destructive condition caused by bacterial infection that affects the hard tissues of the teeth, significantly reducing the quality of life for individuals. Photothermal therapy (PTT) offers a noninvasive and painless treatment for caries, but the use of unsafe laser irradiance limits its application. To address this challenge, we prepared nanoparticles of silver ion-doped Prussian blue (AgPB), which was encased within cationic guar gum (CG) to form the antibacterial PTT hydrogel CG-AgPB with a photothermal conversion efficiency of 34.4%. When exposed to an 808 nm laser at a power density of 0.4 W/cm2, the hydrogel readily reached a temperature of over 50 °C in just 3 min, synchronized by the discharge of Ag+ ions from the interstitial sites of AgPB crystals, resulting in broad-spectrum and synergistic antibacterial activities (>99%) against individual oral pathogens (Streptococcus sanguinis, Streptococcus mutans, and Streptococcus sobrinus) and pathogen-induced biofilms. In vivo, CG-AgPB-mediated PTT demonstrated a capability to profoundly reduce the terminal number of cariogenic bacteria to below 1% in a rat model of caries. Given the outstanding biocompatibility, injectability, and flushability, this CG-AgPB hydrogel may hold promise as a next-generation oral hygiene adjunct for caries management in a clinical setting.

Hydrogel-Based Oxygen and Drug Delivery Dressing for Improved Wound Healing

Herein, we propose a Carbopol hydrogel-based oxygen nanodelivery "nanohyperbaric" system as a wound dressing material for an enhanced wound healing process. Oxygen nanobubbles (ONBs) were used to supply oxygen, and collagenase was added in the gel as a drug model. Both oxygen and collagenase would benefit the wound healing process, and the Carbopol hydrogel serves as the matrix to load ONBs and collagenase in the wound dressing. The obtained ONB-embedded Carbopol hydrogel with collagenase (ONB-CC) could provide 12.08 ± 0.75 μg of oxygen from 1 mL of ONB-CC and exhibited a notable capacity to prolong the oxygen holding for up to 3 weeks and maintained the enzymatic activity of collagenase at more than 0.05 U per 0.1 mL of ONB-CC for up to 17 days. With HDFa cells, the ONB-CC did not show a notable effect on the cell viability. In a scratch assay, the oxygen from ONBs or collagenase aided cell migration; further, the ONB-CC induced the most obvious scratch closure, indicating an improvement in wound healing as a cocktail in the ONB-CC. The mRNA expression further demonstrated the effectiveness of the ONB-CC. Studies in rats with punched wounds treated with the ONB-CC dressing showed improved wound closure. Histopathological images showed that the ONB-CC dressing enhanced re-epithelization and formation of new blood vessels and hair follicles. The proposed ONB-CC has excellent potential as an ideal wound dressing material to accelerate wound healing by integration of multiple functions.

Recent Progress in Implantable Drug Delivery Systems

In recent years, tremendous effort is devoted to developing platforms, such as implantable drug delivery systems (IDDSs), with temporally and spatially controlled drug release capabilities and improved adherence. IDDSs have multiple advantages: i) the timing and location of drug delivery can be controlled by patients using specific stimuli (light, sound, electricity, magnetism, etc.). Some intelligent "closed-loop" IDDS can even realize self-management without human participation. ii) IDDSs enable continuous and stable delivery of drugs over a long period (months to years) and iii) to administer drugs directly to the lesion, thereby helping reduce dosage and side effects. iv) IDDSs enable personalized drug delivery according to patient needs. The high demand for such systems has prompted scientists to make efforts to develop intelligent IDDS. In this review, several common stimulus-responsive mechanisms including endogenous (e.g., pH, reactive oxygen species, proteins, etc.) and exogenous stimuli (e.g., light, sound, electricity, magnetism, etc.), are given in detail. Besides, several types of IDDS reported in recent years are reviewed, including various stimulus-responsive systems based on the above mechanisms, radio frequency-controlled IDDS, "closed-loop" IDDS, self-powered IDDS, etc. Finally, the advantages and disadvantages of various IDDS, bottleneck problems, and possible solutions are analyzed to provide directions for subsequent research.

Engineering Platelet Membrane-Coated Bimetallic MOFs as Biodegradable Nanozymes for Efficient Antibacterial Therapy

Nanocatalytic-based wound therapeutics present a promising strategy for generating reactive oxygen species (ROS) to antipathogen to promote wound healing. However, the full clinical potential of these nanocatalysts is limited by their low reactivity, limited targeting ability, and poor biodegradability in the wound microenvironment. Herein, a bio-organic nanozyme is developed by encapsulating a FeZn-based bimetallic organic framework (MOF) (MIL-88B-Fe/Zn) in platelet membranes (PM@MIL-88B-Fe/Zn) for antimicrobial activity during wound healing. The introduction of Zn in MIL-88B-Fe/Zn modulates the electronic structure of Fe thus accelerating the catalytic kinetics of its peroxidase-like activity to catalytically generate powerful ROS. The platelet membrane coating of MOF innovatively enhanced the interaction between nanoparticles and the biological environment, further developing bacterial-targeted therapy with excellent antibacterial activity against both gram-positive and gram-negative bacteria. Furthermore, this nanozyme markedly suppressed the levels of inflammatory cytokines and promoted angiogenesis in vivo to effectively treat skin surface wounds and accelerate wound healing. PM@MIL-88B-Fe/Zn exhibited superior biodegradability, favourable metabolism and non-toxic accumulation, eliminating concerns regarding side effects from long-term exposure. The high catalytic reactivity, excellent targeting features, and biodegradability of these nanoenzymes developed in this study provide useful insights into the design and synthesis of nanocatalysts/nanozymes for practical biomedical applications.

Recent advances on thermosensitive hydrogels-mediated precision therapy

Precision therapy has become the preferred choice attributed to the optimal drug concentration in target sites, increased therapeutic efficacy, and reduced adverse effects. Over the past few years, sprayable or injectable thermosensitive hydrogels have exhibited high therapeutic potential. These can be applied as cell-growing scaffolds or drug-releasing reservoirs by simply mixing in a free-flowing sol phase at room temperature. Inspired by their unique properties, thermosensitive hydrogels have been widely applied as drug delivery and treatment platforms for precision medicine. In this review, the state-of-the-art developments in thermosensitive hydrogels for precision therapy are investigated, which covers from the thermo-gelling mechanisms and main components to biomedical applications, including wound healing, anti-tumor activity, osteogenesis, and periodontal, sinonasal and ophthalmic diseases. The most promising applications and trends of thermosensitive hydrogels for precision therapy are also discussed in light of their unique features.

Synergistic quorum sensing inhibition and mild-temperature photothermal therapy of integrated nanoplatform for implant-associated biofilm infections

In current clinical practice, the presence of biofilms poses a significant challenge in the effective elimination of bacterial infections because of the physical and chemical barriers formed by biofilms, which offer persistent protection to bacteria. Here, we developed hollow mesoporous polydopamine (hMP) nanoparticles (NPs) loaded with luteolin (Lu) as a quorum sensing inhibitor, which were further coated with hyaluronic acid (HA) shells to create hMP-Lu@HA NPs. We observed that upon reaching the infection site, the HA shells underwent initial degradation by the hyaluronidase enzyme present in the bacterial infection's microenvironment to expose the hMP-Lu NPs. Subsequently, Lu was released in response to the acidic conditions characteristic of bacterial infections, which effectively hindered and dispersed the biofilm. Moreover, when subjected to near-infrared irradiation, the robust photothermal conversion effect of hMP NPs accelerated the release of Lu and disrupted the integrity of the biofilms by localized heating. This dual action enhanced the eradication of the biofilm infection. Importantly, hMP-Lu@HA NPs also promoted tissue regeneration and healing at the implantation site, concurrently addressing biofilm infection. Taken together, this nanosystem, combined with mild-temperature photothermal therapy and quorum sensing inhibition strategy, holds significant potential for applications in the treatment of implantation-associated infections.

Fighting bacteria with bacteria: A biocompatible living hydrogel patch for combating bacterial infections and promoting wound healing

Bacterial infections are among the most critical global health challenges that seriously threaten the security of human. To address this issue, a biocompatible engineered living hydrogel patch was developed by co-embedding engineered photothermal bacteria (EM), photosensitizer (porphyrin) and reactive oxygen species amplifier (laccase) in a protein hydrogel. Remarkably, the genetice engineered bacteria can express melanin granules in vivo and this allows them to exhibit photothermal response upon being exposed to NIR-II laser (1064 nm) irradiation. Besides, electrostatically adhered tetramethylpyridinium porphyrin (TMPyP) on the bacterial surface and encapsulated laccase (Lac) in protein gel can generate highly toxic singlet oxygen (1O2) and hydroxyl radical (·OH) in the presence of visible light and lignin, respectively. Interestingly, the engineered bacteria hydrogel patch (EMTL@Gel) was successfully applied in synergistic photothermal, photodynamic and chemodynamic therapy, in which it was able to efficiently treat bacterial infection in mouse wounds and enhance wound healing. This work demonstrates the concept of "fighting bacteria with bacteria" combining bacterial engineering and material engineering into an engineered living hydrogel path that can synergistically boost the therapeutic outcome. STATEMENT OF SIGNIFICANCE: Genetically engineered bacteria produce melanin granules in vivo, exhibiting remarkable photothermal properties. These bacteria, along with a photosensitizer (TMPyP) and a reactive oxygen species amplifier (laccase), are incorporated into a biocompatible protein hydrogel patch. Under visible light, the patch generates toxic singlet oxygen (1O2) and hydroxyl radical (·OH), demonstrates outstanding synergistic effects in photothermal, photodynamic, and chemodynamic therapy, effectively treating bacterial infections and promoting wound healing in mice.

NF-κB-Signaling-Targeted Immunomodulatory Nanoparticle with Photothermal and Quorum-Sensing Inhibition Effects for Efficient Healing of Biofilm-Infected Wounds

The development of therapeutics with high antimicrobial activity and immunomodulatory effects is urgently needed for the treatment of infected wounds due to the increasing danger posed by recalcitrant-infected wounds. In this study, we developed light-controlled antibacterial, photothermal, and immunomodulatory biomimetic N/hPDA@M nanoparticles (NPs). This nanoplatform was developed by loading flavonoid naringenin onto hollow mesoporous polydopamine NPs in a π-π-stacked configuration and encasing them with macrophage membranes. First, our N/hPDA@M NPs efficiently neutralized inflammatory factors present within the wound microenvironment by the integration of macrophage membranes. Afterward, the N/hPDA@M NPs effectively dismantled bacterial biofilms through a combination of the photothermal properties of PDA and the quorum sensing inhibitory effects of naringenin. It is worth noting that N/hPDA@M NPs near-infrared-enhanced release of naringenin exhibited specificity toward the NF-κB-signaling pathway, effectively mitigating the inflammatory response. This innovative design not only conferred remarkable antibacterial properties upon the N/hPDA@M NPs but also endowed them with the capacity to modulate inflammatory responses, curbing excessive inflammation and steering macrophage polarization toward the M2 phenotype. As a result, this multifaceted approach significantly contributes to expediting the healing process of infected skin wounds.

Biopolymer based nanoparticles and their therapeutic potential in wound healing - A review

Nanoparticles (NPs) have been extensively investigated for their potential in nanomedicine. There is a significant level of enthusiasm about the potential of NPs to bring out a transformative impact on modern healthcare. NPs can serve as effective wound dressings or delivery vehicles due to their antibacterial and pro-wound-healing properties. Biopolymer-based NPs can be manufactured using various food-grade biopolymers, such as proteins, polysaccharides, and synthetic polymers, each offering distinct properties suitable for different applications which include collagen, polycaprolactone, chitosan, alginate, and polylactic acid, etc. Their biodegradable and biocompatible nature renders them ideal nanomaterials for applications in wound healing. Additionally, the nanofibers containing biopolymer-based NPs have shown excellent anti-bacterial and wound healing activity like silver NPs. These NPs represent a paradigm shift in wound healing therapies, offering targeted and personalized solutions for enhanced tissue regeneration and accelerated wound closure. The current review focuses on biopolymer NPs with their applications in wound healing.

AgNPs loaded adenine-modified chitosan composite POSS-PEG hybrid hydrogel with enhanced antibacterial and cell proliferation properties for promotion of infected wound healing

Wound healing is a dynamic and complex process, it's urgent to develop new wound dressings with excellent performance to promote wound healing at the different stages. Here, a novel composite hydrogel dressing composed by silver nanoparticles (AgNPs) impregnated adenine-modified chitosan (CS-A) and octafunctionalized polyhedral oligomeric silsesquioxane (POSS) of benzaldehyde-terminated polyethylene glycol (POSS-PEG-CHO) solution was presented to solve the problem of wound infection. Modification of chitosan with adenine, not only can improve the water solubility of chitosan, but also introduce bioactive substances to promote cell proliferation. CS-A and POSS-PEG-CHO were cross-linked by Schiff-base reaction to form the injectable self-healing hydrogel. On this basis, AgNPs were added into the hydrogel, which endows the hydrogel with better antibacterial activity. Moreover, this kind of hydrogel exhibits excellent cell proliferation properties. Studies demonstrated that the hydrogel can significantly accelerate the closure of infected wounds. The histological analysis and immunofluorescence staining demonstrated that the wounds treated with the composite hydrogel exhibited fewer inflammatory cells, more collagen deposition and angiogenesis, faster regeneration of epithelial tissue. Above all, adenine-modified chitosan composite hydrogel with AgNPs loaded was considered as a dressing material with great application potential for promoting the healing of infected wounds.

Antioxidant and antibacterial hydrogel formed by protocatechualdehyde-ferric iron complex and aminopolysaccharide for infected wound healing

To better treat bacteria-infected wounds and promote healing, new wound dressings must be developed. In this study, we obtained PA@Fe by chelating iron trivalent ions (Fe3+) with protocatechualdehyde (PA), which has a catechol structure. Subsequently, we reacted it with ethylene glycol chitosan (GC) via a Schiff base reaction and loaded vancomycin to obtain an antibacterial Gel@Van hydrogel with a photothermal response. The as-prepared Gel@Van hydrogel exhibited good injectability, self-healing, hemostasis, photothermal stability, biocompatibility, and antioxidant and antibacterial properties. Moreover, Gel@Van hydrogel achieved highly synergistic antibacterial efficacy through photothermal and antibiotic sterilization. In a mouse skin-damaged infection model, Gel@Van hydrogel had a strong ability to promote the healing of methicillin-resistant Staphylococcus aureus (MRSA)-infected wounds, indicating the great potential application value of Gel@Van hydrogel in the field of treating and promoting the healing of infected wounds.

Intra-Articular Injection of PLGA/Polydopamine Core-Shell Nanoparticle Attenuates Osteoarthritis Progression

Osteoarthritis (OA) is a common joint disease characterized by progressive cartilage degeneration. Unfortunately, currently available clinical drugs are mainly analgesics and cannot alleviate the development of OA. Kartogenin (KGN) has been found to promote the differentiation of bone marrow mesenchymal stem cells (BMSCs) into chondrocytes for the treatment of cartilage damage in early OA. However, KGN, as a small hydrophobic molecule, is rapidly cleared from the synovial fluid after intra-articular injection. This study synthesized a KGN-loaded nanocarrier based on PLGA/polydopamine core/shell structure to treat OA. The fluorescence signal of KGN@PLGA/PDA-PEG-E7 nanoparticles lasted for 4 weeks, ensuring long-term sustained release of KGN from a single intra-articular injection. In addition, the polyphenolic structure of PDA enables it to effectively scavenge reactive oxygen species, and the BMSC-targeting peptide E7 (EPLQLKM) endows KGN@PLGA/PDA-PEG-E7 NPs with an effective affinity for BMSCs. As a result, the KGN@PLGA/PDA-PEG-E7 nanoparticles could effectively induce cartilage in vitro and protect the cartilage and subchondral bone in a rat ACLT model. This therapeutic strategy could also be extended to the delivery of other drugs, targeting other tissues to treat joint diseases.

Turning Polysaccharides into Injectable and Rapid Self-Healing Antibacterial Hydrogels for Antibacterial Treatment and Bacterial-Infected Wound Healing

Great efforts have been devoted to the development of novel and multifunctional wound dressing materials to meet the different needs of wound healing. Herein, we covalently grafted quaternary ammonium groups (QAGs) containing 12-carbon straight-chain alkanes to the dextran polymer skeleton. We then oxidized the resulting product into oxidized quaternized dextran (OQD). The obtained OQD polymer is rich in antibacterial QAGs and aldehyde groups. It can react with glycol chitosan (GC) via the Schiff-base reaction to form a multifunctional GC@OQD hydrogel with good self-healing behavior, hemostasis, injectability, inherent superior antibacterial activity, biocompatibility, and excellent promotion of healing of methicillin-resistant Staphylococcus aureus (MRSA)-infected wounds. The biosafe and nontoxic GC@OQD hydrogel with a three-dimensional porous network structure possesses an excellent swelling rate and water retention capacity. It can be used for hemostasis and treating irregular wounds. The designed GC@OQD hydrogel with inherent antibacterial activity possesses good antibacterial efficacy on both S. aureus (Gram-positive bacteria) and Escherichia coli (Gram-negative bacteria), as well as MRSA bacteria, with antibacterial activity greater than 99%. It can be used for the treatment of wounds infected by MRSA and significantly promotes the healing of wounds. Thus, the multifunctional antibacterial GC@OQD hydrogel has the potential to be applied in clinical practice as a wound dressing.

Leveraging the Recent Advancements in GelMA Scaffolds for Bone Tissue Engineering: An Assessment of Challenges and Opportunities

The field of bone tissue engineering has seen significant advancements in recent years. Each year, over two million bone transplants are performed globally, and conventional treatments, such as bone grafts and metallic implants, have their limitations. Tissue engineering offers a new level of treatment, allowing for the creation of living tissue within a biomaterial framework. Recent advances in biomaterials have provided innovative approaches to rebuilding bone tissue function after damage. Among them, gelatin methacryloyl (GelMA) hydrogel is emerging as a promising biomaterial for supporting cell proliferation and tissue regeneration, and GelMA has exhibited exceptional physicochemical and biological properties, making it a viable option for clinical translation. Various methods and classes of additives have been used in the application of GelMA for bone regeneration, with the incorporation of nanofillers or other polymers enhancing its resilience and functional performance. Despite promising results, the fabrication of complex structures that mimic the bone architecture and the provision of balanced physical properties for both cell and vasculature growth and proper stiffness for load bearing remain as challenges. In terms of utilizing osteogenic additives, the priority should be on versatile components that promote angiogenesis and osteogenesis while reinforcing the structure for bone tissue engineering applications. This review focuses on recent efforts and advantages of GelMA-based composite biomaterials for bone tissue engineering, covering the literature from the last five years.

Iron-Single-Atom Nanozyme with NIR Enhanced Catalytic Activities for Facilitating MRSA-Infected Wound Therapy

Patients with methicillin-resistant Staphylococcus aureus (MRSA) infections may have higher death rates than those with non-drug-resistant infections. Nanozymes offer a promising approach to eliminating bacteria by producing reactive oxygen species. However, most of the conventional nanozyme technologies encounter significant challenges with respect to size, composition, and a naturally low number of active sites. The present study synthesizes a iron-single-atom structure (Fe-SAC) via nitrogen doped-carbon, a Fe-N5 catalyst (Fe-SAC) with a high metal loading (4.3 wt.%). This catalyst permits the development of nanozymes consisting of single-atom structures with active sites resembling enzymes, embedded within nanomaterials. Fe-SAC displays peroxidase-like activities upon exposure to H2O2. This structure facilitates the production of hydroxyl radicals, well-known for their strong bactericidal effects. Furthermore, the photothermal properties augment the bactericidal efficacy of Fe-SAC. The findings reveal that Fe-SAC disrupts the bacterial cell membranes and the biofilms, contributing to their antibacterial effects. The bactericidal properties of Fe-SAC are harnessed, which eradicates the MRSA infections in wounds and improves wound healing. Taken together, these findings suggest that single Fe atom nanozymes offer a novel perspective on the catalytic mechanism and design, holding immense potential as next-generation nanozymes.

Polysaccharide hydrogel containing silver nanoparticle@catechol microspheres with photothermal, antibacterial and anti-inflammatory activities for infected-wounds repair

Anti-infection hydrogels have recently aroused enormous attraction, particularly in the treatment of chronic wounds. Herein, silver nanoparticle@catechol formaldehyde resin microspheres (Ag@CFRs) were fabricated by one-step hydrothermal method and subsequently encapsulated in hydrogels which were developed by Schiff base reaction between aldehyde groups in oxidized hyaluronic acid and amino groups in carboxymethyl chitosan. The developed polysaccharide hydrogel exhibited microporous structure, high swelling capacity, favorable mechanical strength, enhanced tissue adhesion and photothermal activities. Additionally, the hydrogel not only ensured long-term and high-efficiency antibacterial performance (99.9 %) toward E. coli and S. aureus, but also realized superior cytocompatibility in vitro. Moreover, based on the triple antibacterial strategies endowed by chitosan, silver nanoparticles and the photothermal properties of catechol microspheres, the composite hydrogel exhibited excellent anti-infection function, significantly downregulated inflammatory factors (TNF-α and IL-1β) and promoted in vivo infected-wound healing. These results demonstrated that the polysaccharide hydrogel containing Ag@CFRs has great potential for infected-wounds repair.

Tailored gelatin methacryloyl-based hydrogel with near-infrared responsive delivery of Qiai essential oils boosting reactive oxygen species scavenging, antimicrobial, and anti-inflammatory activities for diabetic wound healing

The management of diabetic wounds poses a substantial economic and medical burden for diabetic patients. Oxidative stress and persistent bacterial infections are considered to be the primary factors. Qiai essential oil (QEO) exhibits various pharmacological characteristics, including inflammatory-reducing, antibacterial, and antioxidant properties. Nevertheless, the hydrophobic nature and propensity for explosive release of this substance present constraints on its potential for future applications. Here, we developed a stimulus-responsive hydrogel to overcome the multiple limitations of QEO-based wound dressings. The QEO was encapsulated within graphene oxide (GO) through repeated extrusion using an extruder. Subsequently, QEO@GO nanoparticles were incorporated into a Gelatin-methacryloyl (GelMA) hydrogel. The QEO@GO-GelMA hydrogel demonstrated controlled release ablation, photothermal antibacterial effects, and contact ablation against two representative bacterial strains. It effectively reduced reactive oxygen species (ROS) generation, promoted angiogenesis, and decreased levels of the pro-inflammatory cytokine interleukin-6 (IL-6), thereby accelerating the healing process of diabetic wounds. In addition, in vitro and in vivo tests provided further evidence of the favorable biocompatibility of this multifunctional hydrogel dressing. Overall, the QEO@GO-GelMA hydrogel provides numerous benefits, encompassing antimicrobial properties, ROS-scavenging abilities, anti-inflammatory effects, and the capacity to expedite diabetic wound healing. These attributes make it an optimal choice for diabetic wound management.

Microwave Encounters Ionic Liquid: Synergistic Mechanism, Synthesis and Emerging Applications

Progress in microwave (MW) energy application technology has stimulated remarkable advances in manufacturing and high-quality applications of ionic liquids (ILs) that are generally used as novel media in chemical engineering. This Review focuses on an emerging technology via the combination of MW energy and the usage of ILs, termed microwave-assisted ionic liquid (MAIL) technology. In comparison to conventional routes that rely on heat transfer through media, the contactless and unique MW heating exploits the electromagnetic wave-ions interactions to deliver energy to IL molecules, accelerating the process of material synthesis, catalytic reactions, and so on. In addition to the inherent advantages of ILs, including outstanding solubility, and well-tuned thermophysical properties, MAIL technology has exhibited great potential in process intensification to meet the requirement of efficient, economic chemical production. Here we start with an introduction to principles of MW heating, highlighting fundamental mechanisms of MW induced process intensification based on ILs. Next, the synergies of MW energy and ILs employed in materials synthesis, as well as their merits, are documented. The emerging applications of MAIL technologies are summarized in the next sections, involving tumor therapy, organic catalysis, separations, and bioconversions. Finally, the current challenges and future opportunities of this emerging technology are discussed.

Fibronectin Connecting Cell Sheet Based on Click Chemistry for Wound Repair

As a living repair material, cell sheet exhibits significant potential in wound repair. Nonetheless, wound healing is a complicated and protracted process that necessitates specific repair functions at each stage, including hemostasis and antibacterial activity. In this work, on the basis of harvesting the cell sheet via a photothermal response strategy, a fibronectin attached cell sheet (FACS) is prepared to enhance its wound repair capability. For this purpose, the azide group (N3 ) is initially tagged onto the cell surface through metabolic glycoengineering of unnatural sugars, and then the conjugate (DBCO-fibronectin) comprises of the dibenzocyclooctyne (DBCO) and fibronectin with multiple wound repair functions is linked to N3 using click chemistry. Biological evaluations following this demonstrates that the FACS preparation exhibits excellent biocompatibility, and the fibronectin modification enhances the capacity for cell proliferation and migration. Moreover, in vivo wound healing experiment confirms the reparative efficacy of FACS. It not only has a wound closure rate 1.46 times that of a conventional cell sheet but also reduces inflammatory cell infiltration, promotes hair follicle and blood vessel regeneration, and encourages collagen deposition. This strategy holds enormous clinical potential and paves the way for advanced functional modifications of cell sheets.

Generation of a photothermally responsive antimicrobial, bioadhesive gelatin methacryloyl (GelMA) based hydrogel through 3D printing for infectious wound healing

Recently, photothermal nanomaterials has attracted enormous interests owing to their enhanced therapeutic effects and less adverse effects in the treatment of infectious diseases. Herein, this work presents a photothermally responsive antimicrobial, bioadhesive hydrogel through three dimensions (3D) printing technology for treatment the wound infection. The hydrogel is based on a visible-light-activated naturally derived polymer (GelMA), GelMA grafted with dopamine (GelMA-DA) and the polydopamine coated reduced graphene oxide (rGO@PDA), which can provide the multifunctional such as photothermal antibacterial, antioxidant, conductivity, adhesion and hemostasis performance to accelerate wound healing. The developed hydrogel shown the excellent adhesion capability to adhere the in vitro physiological tissues and glass surface. Moreover, the fabricated hydrogel also exhibited excellent cytocompatibility to L929 cells which is a vital biofunction for efficiently promoting cell proliferation and migration in vitro. The hydrogel also showed remarkable photothermally responsive antimicrobial capability against two strains (99.3 % antibacterial ratio for E. coli and 98.6 % antibacterial ratio for S. aureus). Furthermore, it could support the wound repair and regeneration of S. aureus infected full-thickness wound defects in rats. Overall, the 3D printed hydrogel could be used as a photothermal platform for the development of more effective therapies against the infected wound.

Multicargo-loaded inverse opal gelatin hydrogel microparticles for promoting bacteria-infected wound healing

Nowadays, many strategies have been developed to design biomaterials to accelerate bacteria-infected wound healing. Here, we presented a new type of multicargo-loaded inverse opal hydrogel microparticle (IOHM) for regulating oxidative stress, antibiosis, and angiogenesis of the bacteria-infected wound. The methacrylate acylated gelatin (GelMA)-based inverse opal hydrogel microparticles (IOHMs) were obtained by using the colloidal crystal microparticles as templates, and fullerol, silver nanoparticles (Ag NPs), and vascular endothelial growth factor (VEGF) were loaded in IOHMs. The developed multicargo-loaded IOHMs displayed good size distribution and biocompatibility, and when they were applied in cell culture, bacteria culture, and animal experiments, they exhibited excellent anti-oxidative stress properties, antibacterial properties, and angiogenesis. These characteristics of the developed multicargo-loaded IOHMs make them ideal for bacteria-infected wound healing.

Hydrogel-Based Biosensors for Bacterial Infections

Hydrogels are known to have the advantages such as good biodegradability, biocompatibility, and easy functionalization, making them ideal candidates for biosensors. Hydrogel-based biosensors that respond to bacteria-induced microenvironmental changes such as pH, enzymes, antigens, etc., or directly interact with bacterial surface receptors, can be applied for early diagnosis of bacterial infections, providing information for timely treatment while avoiding antibiotic abuse. Furthermore, hydrogel biosensors capable of both bacteria diagnosis and treatment will greatly facilitate the development of point-of-care monitoring of bacterial infections. In this review, the recent advancement of hydrogel-based biosensors for bacterial infection is summarized and discussed. First, the biosensors based on pH-sensitive hydrogels, bacterial-specific secretions-sensitive hydrogels, and hydrogels directly in contact with bacterial surfaces are presented. Next, hydrogel biosensors capable of detecting bacterial infection in the early stage followed by immediate on-demand treatment are discussed. Finally, the challenges and future development of hydrogel biosensors for bacterial infections are proposed.

Cowberry extract loaded chitosan hydrogel with photothermal and antioxidant properties promotes infected wound healing

Bacterial infection and oxidative stress impede clinical wound healing. Herein, the plant-derived cowberry extract (CE) was first explored as a natural photothermal agent and antioxidant to deal with bacterial infection and oxidative stress. After loading in the carboxymethyl chitosan (CMCs)/oxidized dextran (Odex) hydrogel, the photothermal effect of CE was highly enhanced by CMCs. The controlled temperature induced by CE-containing hydrogel under NIR laser irradiation could rapidly (10 min) and effectively kill Staphylococcus aureus (S. aureus, 99.3 %) and Escherichia coli (E. coli, 94.6 %). Besides, this hydrogel exhibited a fast gelation and hemostasis abilities, high stability, adhesion and ROS scavenging capabilities, as well as good injectability and biocompatibility. Above superior properties make this hydrogel to accelerate the wound healing in S. aureus-infected mice, and it is expected to be a potential clinical wound dressing.

Multifunctional polydopamine/hemin-cyclodextrin reinforced chitosan nanocomposite hydrogel: A synergistic platform for wound healing

Chronic cutaneous wounds present a significant challenge for healthcare providers globally, with the risk of bacterial infections emerging as a particularly concerning issue. There is an increasing need to employ a combination of diverse antibacterial strategies to address infections comprehensively in chronic wounds. This study introduces a highly efficient antibacterial platform that encapsulates the NO precursor (BNN6) into β-cyclodextrin-modified hemin-bearing polydopamine nanoparticles called NO/CHPDA. These nanoparticles are seamlessly integrated into a hydrogel composite comprised of L-arginine grafted chitosan (Arg-CS) and oxide dextrans (oDex). The amalgamation of photothermal therapy (PTT), chemodynamic therapy (CDT), and nitric oxide (NO) antibacterial strategies within the NO/CHPDA@Arg-CS/oDex nanocomposite hydrogel demonstrates a synergistic and highly effective capacity to eradicate bacteria and accelerate the wound healing process in vivo. Remarkably, this nanocomposite hydrogel maintains excellent biocompatibility and induces minimal side effects. The resulting nanocomposite hydrogel represents a promising therapeutic solution for treating bacterial infections in wound healing applications.

Advancements in hydrogel-based drug delivery systems for the treatment of inflammatory bowel disease: a review

Inflammatory bowel disease (IBD) is a chronic disorder that affects millions of individuals worldwide. However, current drug therapies for IBD are plagued by significant side effects, low efficacy, and poor patient compliance. Consequently, there is an urgent need for novel therapeutic approaches to alleviate IBD. Hydrogels, three-dimensional networks of hydrophilic polymers with the ability to swell and retain water, have emerged as promising materials for drug delivery in the treatment of IBD due to their biocompatibility, tunability, and responsiveness to various stimuli. In this review, we summarize recent advancements in hydrogel-based drug delivery systems for the treatment of IBD. We first identify three pathophysiological alterations that need to be addressed in the current treatment of IBD: damage to the intestinal mucosal barrier, dysbiosis of intestinal flora, and activation of inflammatory signaling pathways leading to disequilibrium within the intestines. Subsequently, we discuss in depth the processes required to prepare hydrogel drug delivery systems, from the selection of hydrogel materials, types of drugs to be loaded, methods of drug loading and drug release mechanisms to key points in the preparation of hydrogel drug delivery systems. Additionally, we highlight the progress and impact of the hydrogel-based drug delivery system in IBD treatment through regulation of physical barrier immune responses, promotion of mucosal repair, and improvement of gut microbiota. In conclusion, we analyze the challenges of hydrogel-based drug delivery systems in clinical applications for IBD treatment, and propose potential solutions from our perspective.

In vitro and in vivo studies on biodegradable Zn porous scaffolds with a drug-loaded coating for the treatment of infected bone defect

Additively manufactured biodegradable zinc (Zn) scaffolds have great potential to repair infected bone defects due to their osteogenic and antibacterial properties. However, the enhancement of antibacterial properties depends on a high concentration of dissolved Zn2+, which in return deteriorates osteogenic activity. In this study, a vancomycin (Van)-loaded polydopamine (PDA) coating was prepared on pure Zn porous scaffolds to solve the above dilemma. Compared with pure Zn scaffolds according to comprehensive in vitro tests, the PDA coating resulted in a slow degradation and inhibited the excessive release of Zn2+ at the early stage, thus improving cytocompatibility and osteogenic activity. Meanwhile, the addition of Van drug substantially suppressed the attachment and proliferation of S. aureus and E. coli bacterial. Furthermore, in vivo implantation confirmed the simultaneously improved osteogenic and antibacterial functions by using the pure Zn scaffolds with Van-loaded PDA coating. Therefore, it is promising to employ biodegradable Zn porous scaffolds with the proposed drug-loaded coating for the treatment of infected bone defects.

Progress in injectable hydrogels for the treatment of incompressible bleeding: an update

Uncontrollable haemorrhage from deep, noncompressible wounds remains a persistent and intractable challenge, accounting for a very high proportion of deaths in both war and disaster situations. Recently, injectable hydrogels have been increasingly studied as potential haemostatic materials, highlighting their enormous potential for the management of noncompressible haemorrhages. In this review, we summarize haemostatic mechanisms, commonly used clinical haemostatic methods, and the research progress on injectable haemostatic hydrogels. We emphasize the current status of injectable hydrogels as haemostatic materials, including their physical and chemical properties, design strategy, haemostatic mechanisms, and application in various types of wounds. We discuss the advantages and disadvantages of injectable hydrogels as haemostatic materials, as well as the opportunities and challenges involved. Finally, we propose cutting-edge research avenues to address these challenges and opportunities, including the combination of injectable hydrogels with advanced materials and innovative strategies to increase their biocompatibility and tune their degradation profile. Surface modifications for promoting cell adhesion and proliferation, as well as the delivery of growth factors or other biologics for optimal wound healing, are also suggested. We believe that this paper will inform researchers about the current status of the use of injectable haemostatic hydrogels for noncompressible haemorrhage and spark new ideas for those striving to propel this field forward.

Bletilla Striata polysaccharides thermosensitive gel for photothermal treatment of bacterial infection

Skin is the most important defense shield which touched external environment directly. Effectively clearing microbes in infected wound via non-antibiotic therapy is crucial for the promotion of recovery in complex biological environments, and the wound healing is a crucial process after sterilization to avoid superinfection. Herein, a kind of Prussian blue-based photothermal responsive gel, Bletilla striata polysaccharide-mingled, isatin-functionalized Prussian blue gel (PB-ISA/BSP gel) was reported for effective treatment of bacterial infection and wound healing. The introduction of effective components of traditional Chinese medicine (TCM), isatin (ISA), enhanced the efficiency of sterilization synergistically. Furthermore, the process of wound healing was promoted by Bletilla striata polysaccharides (BSP). PB-ISA@BSP had a considerable antibacterial rate with 98.5 % under an 808 nm laser for 10 min in vitro. Besides, PB-ISA/BSP gel showed an effective antibacterial efficacy in vivo and a fast wound healing rate as well. The as-prepared functional particles can invade and destroy bacteria membrane to kill microbes. This work highlights that PB-ISA/BSP gel is a promising antibacterial agent based on synergistically enhanced photothermal effect and wound healing promotion ability and provides inspiration for future therapy based on the synergy between photothermal agent and active components in TCM.

Fluorescent bioinspired albumin/polydopamine nanoparticles and their interactions with Escherichia coli cells

Inspired by the eumelanin aggregates in human skin, polydopamine nanoparticles (PDA NPs) are promising nanovectors for biomedical applications, especially because of their biocompatibility. We synthesized and characterized fluorescent PDA NPs of 10-25 nm diameter based on a protein containing a lysine-glutamate diad (bovine serum albumin, BSA) and determined whether they can penetrate and accumulate in bacterial cells to serve as a marker or drug nanocarrier. Three fluorescent PDA NPs were designed to allow for tracking in three different wavelength ranges by oxidizing BSA/PDA NPs (Ox-BSA/PDA NPs) or labelling with fluorescein 5-isothiocyanate (FITC-BSA/PDA NPs) or rhodamine B isothiocyanate (RhBITC-BSA/PDA NPs). FITC-BSA/PDA NPs and RhBITC-BSA/PDA NPs penetrated and accumulated in both cell wall and inner compartments of Escherichia coli (E. coli) cells. The fluorescence signals were diffuse or displayed aggregate-like patterns with both labelled NPs and free dyes. RhBITC-BSA/PDA NPs led to the most intense fluorescence in cells. Penetration and accumulation of NPs was not accompanied by a bactericidal or inhibitory effect of growth as demonstrated with the Gram-negative E. coli species and confirmed with a Gram-positive bacterial species (Staphylococcus aureus). Altogether, these results allow us to envisage the use of labelled BSA/PDA NPs to track bacteria and carry drugs in the core of bacterial cells.

Acid-Responsive Aggregation of Gold Nanoparticles for the Photothermal Treatment of Bacterial Infections

Photothermal therapy (PTT) is considered to be one of the promising methods to combat pathogenic bacteria. However, traditional PTT is prone to generate undesired temperature increase to surrounding normal tissues, which limits the application of PTT. Herein, an acid-responsive PTT system (Au nanoparticles system: AuNPs-S) was constructed based on the photothermal feature of spherical gold nanoparticles (AuNPs) and the low pH of the bacterial infected site. AuNPs-S is composed of two kinds of AuNPs: AuNPs modified with Asp-Asp-Asp-Asp-Asp-Cys (peptide A) were denoted as AuNPs-A; AuNPs modified with 2,3-dimethylmaleic anhydride (DA) grafted Lys-Gly-Gly-Lys-Gly-Gly-Lys-Cys (peptide B) were denoted as AuNPs-B/DA. AuNPs-B/DA with an acid-responsive moiety showed a charge-convertible feature. The negatively charged AuNPs-B/DA became positively charged AuNPs-B at low pH, aggregating with the negatively charged AuNPs-A via an electrostatic interaction, reaching the threshold to the interparticle plasmonic coupling effect among AuNPs, thereby killing bacteria precisely under the irradiation of near-infrared (NIR) light through the elevated temperature at the targeted area. This acid-responsive PTT strategy supplies an excellent mode for combating bacterial infections with no vital damage to normal tissues.

Functional fluorescent nanomaterials for the detection, diagnosis and control of bacterial infection and biofilm formation: Insight towards mechanistic aspects and advanced applications

Infectious diseases resulting from the high pathogenic potential of several bacteria possesses a major threat to human health and safety. Traditional methods used for screening of these microorganisms face major issues with respect to detection time, selectivity and specificity which may delay treatment for critically ill patients past the optimal time. Thus, a convincing and essential need exists to upgrade the existing methodologies for the fast detection of bacteria. In this context, increasing number of newly emerging nanomaterials (NMs) have been discovered for their effective use and applications in the area of diagnosis in bacterial infections. Recently, functional fluorescent nanomaterials (FNMs) are extensively explored in the field of biomedical research, particularly in developing new diagnostic tools, nanosensors, specific imaging modalities and targeted drug delivery systems for bacterial infection. It is interesting to note that organic fluorophores and fluorescent proteins have played vital role for imaging and sensing technologies for long, however, off lately fluorescent nanomaterials are increasingly replacing these due to the latter's unprecedented fluorescence brightness, stability in the biological environment, high quantum yield along with high sensitivity due to enhanced surface property etc. Again, taking advantage of their photo-excitation property, these can also be used for either photothermal and photodynamic therapy to eradicate bacterial infection and biofilm formation. Here, in this review, we have paid particular attention on summarizing literature reports on FNMs which includes studies detailing fluorescence-based bacterial detection methodologies, antibacterial and antibiofilm applications of the same. It is expected that the present review will attract the attention of the researchers working in this field to develop new engineered FNMs for the comprehensive diagnosis and treatment of bacterial infection and biofilm formation.

Molecular design of an ultra-strong tissue adhesive hydrogel with tunable multifunctionality

Designing adhesive hydrogels with optimal properties for the treatment of injured tissues is challenging due to the tradeoff between material stiffness and toughness while maintaining adherence to wet tissue surfaces. In most cases, bioadhesives with improved mechanical strength often lack an appropriate elastic compliance, hindering their application for sealing soft, elastic, and dynamic tissues. Here, we present a novel strategy for engineering tissue adhesives in which molecular building blocks are manipulated to allow for precise control and optimization of the various aforementioned properties without any tradeoffs. To introduce tunable mechanical properties and robust tissue adhesion, the hydrogel network presents different modes of covalent and noncovalent interactions using N-hydroxysuccinimide ester (NHS) conjugated alginate (Alg-NHS), poly (ethylene glycol) diacrylate (PEGDA), tannic acid (TA), and Fe³⁺ ions. Through combining and tuning different molecular interactions and a variety of crosslinking mechanisms, we were able to design an extremely elastic (924%) and tough (4697 kJ/m³) multifunctional hydrogel that could quickly adhere to wet tissue surfaces within 5 s of gentle pressing and deform to support physiological tissue function over time under wet conditions. While Alg-NHS provides covalent bonding with the tissue surfaces, the catechol moieties of TA molecules synergistically adopt a mussel-inspired adhesive mechanism to establish robust adherence to the wet tissue. The strong adhesion of the engineered bioadhesive patch is showcased by its application to rabbit conjunctiva and porcine cornea. Meanwhile, the engineered bioadhesive demonstrated painless detachable characteristics and in vitro biocompatibility. Additionally, due to the molecular interactions between TA and Fe³⁺, antioxidant and antibacterial properties required to support the wound healing pathways were also highlighted. Overall, by tuning various molecular interactions, we were able to develop a single-hydrogel platform with an "all-in-one" multifunctionality that can address current challenges of engineering hydrogel-based bioadhesives for tissue repair and sealing.

An integrated quorum quenching biocatalytic nanoplatform for synergistic chemo-photothermal eradication of P. aeruginosa biofilm infections

Decontamination of biofilm-associated infections presents a significant challenge due to the physical and chemical barrier created by the formation of extracellular matrices. This barrier restricts the access of antibiotics to the bacterial communities within the biofilm and provides protection to the persister cells, potentially leading to antibiotic resistance. In this study, we have developed an integrated quorum quenching biocatalytic nanoplatform for the synergistic chemo-photothermal eradication of P. aeruginosa biofilm infections. Ciprofloxacin (Cip), a model antibiotic, was absorbed onto PDA NPs through π-π stacking. Additionally, acylase (AC) was immobilized on PDA NPs through Schiff base reaction and Michael addition, resulting in the formation of the biocatalytic nanoplatform (PDA-Cip-AC NPs). This biocatalytic nanoplatform was able to enzymatically degrade AHL signaling molecules, thus achieving efficient quorum quenching activity to prevent biofilm formation. Furthermore, the NIR light-triggered on-demand Ciprofloxacin release further enhanced the eradication of P. aeruginosa biofilm infections with a synergy of local hyperthermia. We envision that this integrated quorum quenching nanoplatform provides a reliable tool for combating P. aeruginosa biofilm infections. STATEMENT OF SIGNIFICANCE: An integrated quorum quenching biocatalytic nanoplatform has been developed for the eradication of P. aeruginosa biofilm infections. Quorum-sensing signals play a crucial role in modulating bacterial cell-to-cell communication, biofilm formation, and secretion of virulence factors. This biocatalytic nanoplatform efficiently degrades AHL signaling molecules, thereby blocking cell-to-cell communication and preventing biofilm formation. Additionally, local hyperthermia and on-demand Ciprofloxacin release were achieved through NIR irradiation, working synergistically to eradicate P. aeruginosa biofilm infections.

Tailored biomedical materials for wound healing

Wound healing is a long-term, multi-stage biological process that mainly includes haemostatic, inflammatory, proliferative and tissue remodelling phases. Controlling infection and inflammation and promoting tissue regeneration can contribute well to wound healing. Smart biomaterials offer significant advantages in wound healing because of their ability to control wound healing in time and space. Understanding how biomaterials are designed for different stages of wound healing will facilitate future personalized material tailoring for different wounds, making them beneficial for wound therapy. This review summarizes the design approaches of biomaterials in the field of anti-inflammatory, antimicrobial and tissue regeneration, highlights the advanced precise control achieved by biomaterials in different stages of wound healing and outlines the clinical and practical applications of biomaterials in wound healing.

Applications of Degradable Hydrogels in Novel Approaches to Disease Treatment and New Modes of Drug Delivery

Hydrogels are particularly suitable materials for loading drug delivery agents; their high water content provides a biocompatible environment for most biomolecules, and their cross-linked nature protects the loaded agents from damage. During delivery, the delivered substance usually needs to be released gradually over time, which can be achieved by degradable cross-linked chains. In recent years, biodegradable hydrogels have become a promising technology in new methods of disease treatment and drug delivery methods due to their many advantageous properties. This review briefly discusses the degradation mechanisms of different types of biodegradable hydrogel systems and introduces the specific applications of degradable hydrogels in several new methods of disease treatment and drug delivery methods.

Smart and versatile biomaterials for cutaneous wound healing

The global increase of cutaneous wounds imposes huge health and financial burdens on patients and society. Despite improved wound healing outcomes, conventional wound dressings are far from ideal, owing to the complex healing process. Smart wound dressings, which are sensitive to or interact with changes in wound condition or environment, have been proposed as appealing therapeutic platforms to effectively facilitate wound healing. In this review, the wound healing processes and features of existing biomaterials are firstly introduced, followed by summarizing the mechanisms of smart responsive materials. Afterwards, recent advances and designs in smart and versatile materials of extensive applications for cutaneous wound healing were submarined. Finally, clinical progresses, challenges and future perspectives of the smart wound dressing are discussed. Overall, by mapping the composition and intrinsic structure of smart responsive materials to their individual needs of cutaneous wounds, with particular attention to the responsive mechanisms, this review is promising to advance further progress in designing smart responsive materials for wounds and drive clinical translation.

Two-dimensional TiO nanosheets with photothermal effects for wound sterilization

To combat multidrug-resistant bacteria, researchers have poured into the development and design of antimicrobial agents. Here, low-cost two-dimensional (2D) antibacterial material titanium monoxide nanosheets (TiO NSs) were prepared by an ultrasonic-assisted liquid-phase exfoliation method. When cultured with bacteria, TiO NSs showed intrinsic antimicrobial capacity, possibly due to membrane damage caused by the sharp edges of TiO NSs. Under near-infrared (NIR) laser irradiation, TiO NSs showed high photothermal conversion efficiency (PTCE) and sterilization efficiency. By combining these two antibacterial mechanisms, TiO NSs exhibited a strong killing effect on Gram-negative Escherichia coli (E. coli) and Gram-positive methicillin-resistant Staphylococcus aureus (MRSA). Especially after treatment with TiO NSs (150 μg mL-1) +near-infrared (NIR) light irradiation, both bacteria were completely killed. In vivo experiments on wound repair of bacterial infection further confirmed its antibacterial effect. In addition, TiO NSs had no obvious toxicity or side effects, so as a kind of broad-spectrum 2D antibacterial nanoagent, TiO NSs have broad application prospects in the field of pathogen infection.

Multifunctional Double-Layer and Dual Drug-Loaded Microneedle Patch Promotes Diabetic Wound Healing

Chronic nonhealing diabetic wounds are a serious complication of diabetes, with a high morbidity rate that can cause disability or death. The long period of inflammation and dysfunctional angiogenesis are the main reasons for wound-healing difficulty in diabetes. In this study, a multifunctional double-layer microneedle (DMN) is constructed to control infection and promote angiogenesis, meeting the multiple demands of the healing process of a diabetic wound. The double-layer microneedle is consisted in a hyaluronic acid substrate and a mixture of carboxymethyl chitosan and gelatin as the tip. The antibacterial drug tetracycline hydrochloride (TH) is loaded into the substrate of the microneedle to achieve rapid sterilization and promote resistance to external bacterial infections. The microneedle tip loaded with recombinant human epidermal growth factor (rh-EGF) is inserted into the skin, in response to gelatinase produced by resident microbe and disassociate to achieve the enzymatic response release. The double-layer drug-loaded microneedles (DMN@TH/rh-EGF) have antibacterial and antioxidant effects, and promote cell migration and angiogenesis in vitro. In an in vivo diabetic wound model, using rats, the DMN@TH/rh-EGF patch is able to inhibit inflammation, promote angiogenesis, collagen deposition, and tissue regeneration during the wound healing process, promoting its healing.

NIR-responsive carrier-free nanoparticles based on berberine hydrochloride and indocyanine green for synergistic antibacterial therapy and promoting infected wound healing

Bacterial infections cause severe health conditions, resulting in a significant economic burden for the public health system. Although natural phytochemicals are considered promising anti-bacterial agents, they suffer from several limitations, such as poor water solubility and low bioavailability in vivo, severely restricting their wide application. Herein, we constructed a near-infrared (NIR)-responsive carrier-free berberine hydrochloride (BH, phytochemicals)/indocyanine green (ICG, photosensitizer) nanoparticles (BI NPs) for synergistic antibacterial of an infected wound. Through electrostatic interaction and π-π stacking, the hydrophobic BH and amphiphilic ICG are initially self-assembled to generate carrier-free nanoparticles. The obtained BI NPs demonstrated NIR-responsive drug release behavior and better photothermal conversion efficiency of up to 36%. In addition, BI NPs stimulated by NIR laser exhibited remarkable antibacterial activity, which realized the synergistic antibacterial treatment and promoted infected wound healing. In summary, the current research results provided a candidate strategy for self-assembling new BI NPs to treat bacterial infections synergistically.

Injectable, antibacterial, and oxygen-releasing chitosan-based hydrogel for multimodal healing of bacteria-infected wounds

Bacterial infection is one of the main challenges of wound healing. It imposes financial and healthcare costs. The emergence of antibiotic-resistant bacteria has increased concerns about this challenge, and made finding alternative solutions a crucial aim. We created a new, antibacterial, multifunctional hydrogel with synergistic chemodynamic and photothermal features for wound-healing applications. We fabricated a chitosan (CT)-based hydrogel containing tannic acid (TA), Fe, and MnO2 nanosheets (CT-TA-Fe-MnO2) via a simple method and characterized it. The antibacterial features (resulting from the production of reactive oxygen species within bacterial cells) and healing ability (via anti-inflammatory and hemostatic features) of the hydrogel were confirmed in vitro. In vivo results revealed the effectiveness of the CT-TA-Fe-MnO2 hydrogel in decreasing the hemostatic time, improving anti-inflammatory effects, and promoting wound healing during 14 days by enhancing the deposition and maturation of collagen fibers without affecting the vital organs. The fabricated CT-TA-Fe-MnO2 hydrogel could be a promising candidate with antibacterial and anti-inflammatory activities suitable for wound-healing applications.