A bionic cellulose nanofiber-based nanocage wound dressing for NIR-triggered multiple synergistic therapy of tumors and infected wounds

Renewable biomass-based aerogels: from structural design to functional regulation

Global population growth and industrialization have exacerbated the nonrenewable energy crises and environmental issues, thereby stimulating an enormous demand for producing environmentally friendly materials. Typically, biomass-based aerogels (BAs), which are mainly composed of biomass materials, show great application prospects in various fields because of their exceptional properties such as biocompatibility, degradability, and renewability. To improve the performance of BAs to meet the usage requirements of different scenarios, a large number of innovative works in the past few decades have emphasized the importance of micro-structural design in regulating macroscopic functions. Inspired by the ubiquitous random or regularly arranged structures of materials in nature ranging from micro to meso and macro scales, constructing different microstructures often corresponds to completely different functions even with similar biomolecular compositions. This review focuses on the preparation process, design concepts, regulation methods, and the synergistic combination of chemical compositions and microstructures of BAs with different porous structures from the perspective of gel skeleton and pore structure. It not only comprehensively introduces the effect of various microstructures on the physical properties of BAs, but also analyzes their potential applications in the corresponding fields of thermal management, water treatment, atmospheric water harvesting, CO2 absorption, energy storage and conversion, electromagnetic interference (EMI) shielding, biological applications, etc. Finally, we provide our perspectives regarding the challenges and future opportunities of BAs. Overall, our goal is to provide researchers with a thorough understanding of the relationship between the microstructures and properties of BAs, supported by a comprehensive analysis of the available data.

Flexible, biodegradable ultrasonic wireless electrotherapy device based on highly self-aligned piezoelectric biofilms

Biodegradable piezoelectric devices hold great promise in on-demand transient bioelectronics. Existing piezoelectric biomaterials, however, remain obstacles to the development of such devices due to difficulties in large-scale crystal orientation alignment and weak piezoelectricity. Here, we present a strategy for the synthesis of optimally orientated, self-aligned piezoelectric γ-glycine/polyvinyl alcohol (γ-glycine/PVA) films via an ultrasound-assisted process, guided by density functional theory. The first-principles calculations reveal that the negative piezoelectric effect of γ-glycine originates from the stretching and compression of glycine molecules induced by hydrogen bonding interactions. The synthetic γ-glycine/PVA films exhibit a piezoelectricity of 10.4 picocoulombs per newton and an ultrahigh piezoelectric voltage coefficient of 324 × 10-3 volt meters per newton. The biofilms are further developed into flexible, bioresorbable, wireless piezo-ultrasound electrotherapy devices, which are demonstrated to shorten wound healing by ~40% and self-degrade in preclinical wound models. These encouraging results offer reliable approaches for engineering piezoelectric biofilms and developing transient bioelectronics.

Multimodal Imaging-Guided Synergistic Photodynamic Therapy Using Carbonized Zn/Co Metal-Organic Framework Loaded with Cytotoxin Against Liver Cancer

Purpose

The study aimed to address the non-specific toxicity of cytotoxins (CTX) in liver cancer treatment and explore their combined application with the photosensitizer Ce6, co-loaded into carbonized Zn/Co bimetallic organic frameworks. The goal was to achieve controlled CTX release and synergistic photodynamic therapy, with a focus on evaluating anti-tumor activity against human liver cancer cell lines (Hep G2).

Methods

Purified cobra cytotoxin (CTX) and photosensitizer Ce6 were co-loaded into carbonized Zn/Co bimetallic organic frameworks, resulting in RGD-PDA@C-ZIF@(CTX+Ce6). The formulation was designed with surface-functionalization using polydopamine and tumor-penetrating peptide RGD. This approach aimed to facilitate controlled CTX release and enhance the synergistic effect of photodynamic therapy. The accumulation of RGD-PDA@C-ZIF@(CTX+Ce6) at tumor sites was achieved through RGD's active targeting and the enhanced permeability and retention (EPR) effect. In the acidic tumor microenvironment, the porous structure of the metal-organic framework disintegrated, releasing CTX and Ce6 into tumor cells.

Results

Experiments demonstrated that RGD-PDA@C-ZIF@(CTX+Ce6) nanoparticles, combined with near-infrared laser irradiation, exhibited optimal anti-tumor effects against human liver cancer cells. The formulation showcased heightened anti-tumor activity without discernible systemic toxicity.

Conclusion

The study underscores the potential of utilizing metal-organic frameworks as an efficient nanoplatform for co-loading cytotoxins and photodynamic therapy in liver cancer treatment. The developed formulation, RGD-PDA@C-ZIF@(CTX+Ce6), offers a promising avenue for advancing the clinical application of cytotoxins in oncology, providing a solid theoretical foundation for future research and development.

Cellulose nanofiber-mediated manifold dynamic synergy enabling adhesive and photo-detachable hydrogel for self-powered E-skin

Self-powered skin attachable and detachable electronics are under intense development to enable the internet of everything and everyone in new and useful ways. Existing on-demand separation strategies rely on complicated pretreatments and physical properties of the adherends, achieving detachable-on-demand in a facile, rapid, and universal way remains challenging. To overcome this challenge, an ingenious cellulose nanofiber-mediated manifold dynamic synergy strategy is developed to construct a supramolecular hydrogel with both reversible tough adhesion and easy photodetachment. The cellulose nanofiber-reinforced network and the coordination between Fe ions and polymer chains endow the dynamic reconfiguration of supramolecular networks and the adhesion behavior of the hydrogel. This strategy enables the simple and rapid fabrication of strong yet reversible hydrogels with tunable toughness ((Valuemax-Valuemin)/Valuemax of up to 86%), on-demand adhesion energy ((Valuemax-Valuemin)/Valuemax of up to 93%), and stable conductivity up to 12 mS cm-1. We further extend this strategy to fabricate different cellulose nanofiber/Fe3+-based hydrogels from various biomacromolecules and petroleum polymers, and shed light on exploration of fundamental dynamic supramolecular network reconfiguration. Simultaneously, we prepare an adhesive-detachable triboelectric nanogenerator as a human-machine interface for a self-powered wireless monitoring system based on this strategy, which can acquire the real-time, self-powered monitoring, and wireless whole-body movement signal, opening up possibilities for diversifying potential applications in electronic skins and intelligent devices.

In situ light-activated materials for skin wound healing and repair: A narrative review

Dermal wounds are a major global health burden made worse by common comorbidities such as diabetes and infection. Appropriate wound closure relies on a highly coordinated series of cellular events, ultimately bridging tissue gaps and regenerating normal physiological structures. Wound dressings are an important component of wound care management, providing a barrier against external insults while preserving the active reparative processes underway within the wound bed. The development of wound dressings with biomaterial constituents has become an attractive design strategy due to the varied functions intrinsic in biological polymers, such as cell instructiveness, growth factor binding, antimicrobial properties, and tissue integration. Using photosensitive agents to generate crosslinked or photopolymerized dressings in situ provides an opportunity to develop dressings rapidly within the wound bed, facilitating robust adhesion to the wound bed for greater barrier protection and adaptation to irregular wound shapes. Despite the popularity of this fabrication approach, relatively few experimental wound dressings have undergone preclinical translation into animal models, limiting the overall integrity of assessing their potential as effective wound dressings. Here, we provide an up-to-date narrative review of reported photoinitiator- and wavelength-guided design strategies for in situ light activation of biomaterial dressings that have been evaluated in preclinical wound healing models.

Recent advances and biomedical application of 3D printed nanocellulose-based adhesive hydrogels: A review

Nanocellulose-based tissue adhesives show promise for achieving rapid hemostasis and effective wound healing. Conventional methods, such as sutures and staples, have limitations, prompting the exploration of bioadhesives for direct wound adhesion and minimal tissue damage. Nanocellulose, a hydrolysis product of cellulose, exhibits superior biocompatibility and multifunctional properties, gaining interest as a base material for bioadhesive development. This study explores the potential of nanocellulose-based adhesives for hemostasis and wound healing using 3D printing techniques. Nanocellulose enables the creation of biodegradable adhesives with minimal adverse effects and opens avenues for advanced wound healing and complex tissue regeneration, such as skin, blood vessels, lungs, cartilage, and muscle. This study reviews recent trends in various nanocellulose-based 3D printed hydrogel patches for tissue engineering applications. The review also introduces various types of nanocellulose and their synthesis, surface modification, and bioadhesive fabrication techniques via 3D printing for smart wound healing.

Platelet rich fibrin and simvastatin-loaded pectin-based 3D printed-electrospun bilayer scaffold for skin tissue regeneration

Designing multifunctional wound dressings is a prerequisite to prevent infection and stimulate healing. In this study, a bilayer scaffold (BS) with a top layer (TL) comprising 3D printed pectin/polyacrylic acid/platelet rich fibrin hydrogel (Pec/PAA/PRF) and a bottom nanofibrous layer (NL) containing Pec/PAA/simvastatin (SIM) was produced. The biodegradable and biocompatible polymers Pec and PAA were cross-linked to form hydrogels via Ca2+ activation through galacturonate linkage and chelation, respectively. PRF as an autologous growth factor (GF) source and SIM together augmented angiogenesis and neovascularization. Because of 3D printing, the BS possessed a uniform distribution of PRF in TL and an average fiber diameter of 96.71 ± 18.14 nm was obtained in NL. The Young's modulus of BS was recorded as 6.02 ± 0.31 MPa and its elongation at break was measured as 30.16 ± 2.70 %. The wound dressing gradually released growth factors over 7 days of investigation. Furthermore, the BS significantly outperformed other groups in increasing cell viability and in vivo wound closure rate (95.80 ± 3.47 % after 14 days). Wounds covered with BS healed faster with more collagen deposition and re-epithelialization. The results demonstrate that the BS can be a potential remedy for skin tissue regeneration.

Phosvitin-based hydrogels prepared in AmimCl under magnetic field treatment: Structural characteristics, biological functions, and application in skin wound healing

Due to the serious bacterial infection of skin and the waste of petroleum-based materials, there is an urgent need to develop natural biodegradable wound dressings with high antibacterial activity. Phosvitin (PSV) has shown its natural antioxidant and antibacterial properties, making it an excellent material for preparing wound healing dressings. In this study, we investigated the effect of magnetic field on the preparation of PSV-Microcrystalline Cellulose (MCC) composite hydrogels in 1-Allyl-3-methylimidazolium chloride (AmimCl) system. The results showed that the prepared hydrogels exhibited homogeneous surface structure, suitable swelling capacity and elasticity modulus, and sufficient thermal stability. The excellent antibacterial and antioxidant activities of hydrogels were mainly resulting from AmimCl and PSV, respectively, and the properties were enhanced after magnetic field treatment. The proteomics analysis indicated that AmimCl can readily penetrate the biological membranes of Staphylococcus aureus (S. aureus), upsetting the metabolism and reducing the virulence. The hydrogels showed great blood compatibility. Compared with the commercial materials, the 5 mT-treated hydrogels presented a comparable wound healing rate in the full-thickness skin injury model. On day 7, the wound healing rate of the 5 mT group reached approximately 84.40 %, which was significantly higher than that of the control group, 72.88 % (P < 0.05). In conclusion, our work provides experience for the development of biodegradable materials combined in ionic liquids and magnetic field, and explores their applications in wound healing dressings.

Development of nanofibrous scaffolds containing polylactic acid modified with turmeric and hydroxyapatite/vivianite nanoparticles for wound dressing applications

Damaging the outer layer of the body (the skin) has been a common issue for decades. Fabrication of nanofibrous membranes via the electrospinning technique for the sake of making the wound healing process more facile has caught a lot of interest. For this purpose, a polymeric scaffold of polylactic acid (PLA) was doped with nanoparticles with different concentrations of turmeric/hydroxyapatite/vivianite/graphene oxide. The obtained membrane was tested by XRD, SEM, FTIR, and XPS. The surface topography of the scaffold has experienced changes upon adding different concentrations of the nanoparticles. The contact angle was measured by water droplets. It accentuated change in CA starting from 43.9o for pure condition of PLA to 67.7o for PLA/turmeric/vivianite. The thermogravimetric analysis (TGA) test stated that the PLA scaffold features are thermally stable in relatively high-temperature conditions initiating from room temperature to about 300 °C, meeting the maximum loss in mass of about 5 %. The cell viability was carried out in prepared vitro for the sample which contains PLA/turmeric/vivianite/GO, it was elucidated that the IC50 was around 3060 μg/ml.

Sodium hyaluronate hydrogel for wound healing and human health monitoring based on deep eutectic solvent

Hydrogel dressings traditionally promote wound healing by maintaining moisture and preventing infection rather than by actively stimulating the skin to regulate cell behavior. Electrical stimulation (ES) is known to modulate skin cell behavior and to promote wound healing. This study describes the first multifunctional conductive hydrogel for wound healing and health monitoring based on a deep eutectic solvent (DES). Sodium hyaluronate and polydopamine constituted the hydrogel skeleton, and tea tree oil and Panax notoginseng extract were used as the active ingredients to induce adhesion, promote antioxidant and antibacterial activity, and support biocompatibility of the hydrogel. The inclusion of DES increases the temperature resistance of the hydrogel and improves its environmental adaptability. We used a small, portable coin battery-powered to provide electrical stimulation. Treatment with both the hydrogel and ES resulted in a stronger therapeutic effect than that provided by the commercial DuoDERM dressing. The hydrogel detected movement and strain when applied as a sensor. Overall, this study reports the development of a multifunctional conductive hydrogel dressing based on DES as a wound healing and health monitor.

Drug delivery nanoparticles for preventing implant bacterial infections based on the bacteria and immunity mechanisms

Implant dysfunction and failure during medical treatment can be attributed to bacterial infection with Staphylococcus aureus and Enterococcus faecalis, which are the prevalent strains responsible for implant infections. Currently, antibiotics are primarily used either locally or systemically to prevent and treat bacterial infections in implants. However, the effectiveness of this approach is unsatisfactory. Therefore, the development of new antimicrobial medications is crucial to address the clinical challenges associated with implant infections. In this study, a nanoparticle (ICG+RSG) composed of indocyanine green (ICG) and rosiglitazone (RSG), and delivered using 1,2-dipalmitoyl-snglycero-3-phosphocholine (DPPC) was prepared. ICG+RSG has photothermal and photodynamic properties to eliminate bacteria at the infection site by releasing reactive oxygen species and increasing the temperature. Additionally, it regulates phagocytosis and macrophage polarization to modulate the immune response in the body. ICG+RSG kills bacteria and reduces tissue inflammation, showing potential for preventing implant infections.

Green, pH-Sensitive, Highly Stretchable, and Hydrogen Bond-Dominated Ionogel for Wound Healing Activity

Traditional hydrogel dressings generally have poor mechanical properties and stability when subjected to external stress due to the undesirable chain entanglement structure of their single valence bond compositions. Therefore, it is particularly important to develop a type of gel dressing with good mechanical strength, stability, and environment-friendly monitoring. In this work, a transparent, pH-sensitive, highly stretchable, and biocompatible anthocyanidin ionogel dressing was prepared, realizing green and accurate detection. Attributed to the antibacterial activity of the ionic liquid, the biocompatibility of the pectin, and the ability to scavenge free radicals of the anthocyanidin, the ionogel dressing exhibited excellent re-epithelialization in the 14 day wound healing process. Besides, changes in pH values monitoring of the ionogel over 3 days coincided with normal wound exudate. The obtained ionogel also showed good water retention, swelling properties, mechanical stretchability, and 5 week stability, illustrating great potential in wound dressings.

Highly Biocompatible Polyester-Based Piezoelectric Elastomer with Antitumor and Antibacterial Activity for Ultrasound-Enhanced Piezoelectric Therapy

Currently, the use of piezoelectric materials to provide sustainable and noninvasive bioelectric stimulation to eradicate tumor cells and accelerate wound healing has raised wide attention. The development of a multifunctional piezoelectric elastomer with the ability to perform in situ tumor therapy as well as wound repair is of paramount importance. However, current piezoelectric materials have a large elastic modulus and limited stretchability, making it difficult to match with the dynamic curvature changes of the wound. Therefore, by copolymerizing lactic acid, butanediol, sebacic acid, and itaconic acid to develop a piezoelectric elastomer (PLBSIE), we construct a new ultrasound-activated PLBSIE-based tumor/wound unified therapeutic platform. Excitedly, it showed outstanding piezoelectric performance and high stretchability, and the separated carrier could react with water to generate highly cytotoxic reactive oxygen species (ROS), contributing to effectively killing tumor cells and eliminating bacteria through piezoelectric therapy. In addition, ultrasound-triggered piezoelectric effects could promote the migration and differentiation of wound-healing-related cells, thus accelerating wound healing. Herein, such a piezoelectric elastomer exerted a critical role in postoperative tumor-induced wound therapy and healing with the merits of possessing multifunctional abilities. Taken together, the developed ultrasound-activated PLBSIE will offer a comprehensive treatment for postoperative osteosarcoma therapy.

Stimuli-Actuated Turn-On Theranostic Nanoplatforms for Imaging-Guided Antibacterial Treatment

Antibacterial theranostic nanoplatforms, which integrate diagnostic and therapeutic properties, exhibit gigantic application prospects in precision medicine. However, traditional theranostic nanoplatforms usually present an always-on signal output, which leads to poor specificity or selectivity in the treatment of bacterial infections. To address this challenge, stimuli-actuated turn-on nanoplatforms are developed for simultaneous activation of diagnostic signals (e.g., fluorescent, photoacoustic, magnetic signals) and initiation of antibacterial treatment. Specifically, by combining the infection microenvironment-responsive activation of visual signals and antibacterial activity, these theranostic nanoplatforms exert both higher accurate diagnosis rates and more effective treatment effects. In this review, the imaging and treatment strategies that are commonly used in the clinic are first briefly introduced. Next, the recent progress of stimuli-actuated turn-on theranostic nanoplatforms for treating bacterial infectious diseases is summarized in detail. Finally, current bottlenecks and future opportunities of antibacterial theranostic nanoplatforms are also outlined and discussed.

Physical dynamic double-network hydrogels as dressings to facilitate tissue repair

Double-network hydrogels can be tuned to have high mechanical strength, stability, elasticity and bioresponsive properties, which can be combined to create self-healing, adhesive and antibacterial wound dressings. Compared with single-network hydrogel, double-network hydrogel shows stronger mechanical properties and better stability. In comparison with chemical bonds, the cross-linking in double networks makes them more flexible than single-network hydrogels and capable of self-healing following mechanical damage. Here, we present the stepwise synthesis of physical double-network hydrogels where hydrogen bonds and coordination reactions provide self-healing, pH-responsive, tissue-adhesive, antioxidant, photothermal and antibacterial properties, and can be removed on demand. We then explain how to carry out physical, chemical and biological characterizations of the hydrogels for use as wound dressings, yet the double-network hydrogels could also be used in different applications such as tissue engineering scaffolds, cell/drug delivery systems, hemostatic agents or in flexible wearable devices for monitoring physiological and pathological parameters. We also outline how to use the double-network hydrogels in vivo as wound dressings or hemostatic agents. The synthesis of the ureido-pyrimidinone-modified gelatin, catechol-modified polymers and the hydrogels requires 84 h, 48 h and 1 h, respectively, whereas the in vivo assays require 3.5 weeks. The procedure is suitable for users with expertise in biomedical polymer materials.

Enhanced Transdermal Peptide-Modified Flexible Liposomes for Efficient Percutaneous Delivery of Chrysomycin A to Treat Subcutaneous Melanoma and Intradermal MRSA Infection

Superficial skin diseases, including skin infections and tumors, are common healthcare burdens. In this study, the in vivo activity of chrysomycin A (CA) is explored, and a transdermal liposomal CA formulation is further constructed for the simultaneous treatment of cutaneous melanoma and cutaneous methicillin-resistant Staphylococcus aureus (MRSA) infection. The prepared liposomes (TD-LP-CA) display a strong antitumor effect with an IC50 value of less than 0.1 µm in B16-F10 cells, suppress the proliferation of MRSA with a minimum inhibitory concentration (MIC) of 1 µm, and eradicate established MRSA biofilms at 10× MIC in vitro. More importantly, TD-LP-CA shows enhanced stratum corneum (SC) penetration, reaching more than 500 µm beneath the skin's surface due to modification with the TD peptide, and demonstrates excellent subcutaneous tumor penetration after skin application in vivo. TD-LP-CA displays an excellent therapeutic effect against intradermal MRSA infection in mice after topical dermal administration, as well as a moderate inhibitory effect on subcutaneous melanoma with a 75% tumor inhibition rate. The liposomes prepared herein can be a promising carrier for transcutaneous CA transfer for the treatment of superficial diseases such as skin tumors and infections due to their ability to overcome the skin barrier.

Current advances of nanocellulose application in biomedical field

Nanocellulose (NC) is a natural fiber that can be extracted in fibrils or crystals form from different natural sources, including plants, bacteria, and algae. In recent years, nanocellulose has emerged as a sustainable biomaterial for various medicinal applications including drug delivery systems, wound healing, tissue engineering, and antimicrobial treatment due to its biocompatibility, low cytotoxicity, and exceptional water holding capacity for cell immobilization. Many antimicrobial products can be produced due to the chemical functionality of nanocellulose, such disposable antibacterial smart masks for healthcare use. This article discusses comprehensively three types of nanocellulose: cellulose nanocrystals (CNC), cellulose nanofibrils (CNF), and bacterial nanocellulose (BNC) in view of their structural and functional properties, extraction methods, and the distinctive biomedical applications based on the recently published work. On top of that, the biosafety profile and the future perspectives of nanocellulose-based biomaterials have been further discussed in this review.

Electroactive Hydrogels with Photothermal/Photodynamic Effects for Effective Wound Healing Assisted by Polydopamine-Modified Graphene Oxide

Antibacterial hydrogel wound dressings have attracted considerable attention in recent years. However, bacterial infections can occur at any point during the wound-healing process. There is a demand for hydrogels that possess on-demand antibacterial and excellent wound repair properties. Herein, we report a near-infrared (NIR)-light-responsive indocyanine green (ICG)-loaded polydopamine (PDA)-mediated graphene oxide (PGO) and amorphous calcium phosphate (CaP)-incorporated poly(vinyl alcohol) (PVA) hydrogel using a mussel-inspired approach. PGO was reduced by PDA, which endowed the hydrogel with electroactivity and provided abundant sites for loading ICG. Amorphous CaP was formed in situ in the PVA hydrogel to enhance its mechanical properties and biocompatibility. Taking advantage of the high photothermal and photodynamic efficiency of ICG-PGO, the ICG-PGO-CaP-PVA hydrogel exhibited fascinating on-demand antibacterial activity through NIR light irradiation. Moreover, the thermally induced gel-sol conversion of PVA accelerated the release of Ca ions and allowed the hydrogel to adapt to irregular wounds. Meanwhile, PGO endows the hydrogel with conductivity and cell affinity, which facilitate endogenous electrical signal transfer to control cell behavior. In vitro and in vivo studies demonstrated that the ICG-PGO-CaP-PVA hydrogel exhibited a strong tissue repair activity under NIR light irradiation. This mussel-inspired strategy offers a novel way to design hydrogel dressings for wound healing.

Double-network hydrogel enhanced by SS31-loaded mesoporous polydopamine nanoparticles: Symphonic collaboration of near-infrared photothermal antibacterial effect and mitochondrial maintenance for full-thickness wound healing in diabetes mellitus

Diabetic wound healing has become a serious healthcare challenge. The high-glucose environment leads to persistent bacterial infection and mitochondrial dysfunction, resulting in chronic inflammation, abnormal vascular function, and tissue necrosis. To solve these issues, we developed a double-network hydrogel, constructed with pluronic F127 diacrylate (F127DA) and hyaluronic acid methacrylate (HAMA), and enhanced by SS31-loaded mesoporous polydopamine nanoparticles (MPDA NPs). As components, SS31, a mitochondria-targeted peptide, maintains mitochondrial function, reduces mitochondrial reactive oxygen species (ROS) and thus regulates macrophage polarization, as well as promoting cell proliferation and migration, while MPDA NPs not only scavenge ROS and exert an anti-bacterial effect by photothermal treatment under near-infrared light irradiation, but also control release of SS31 in response to ROS. This F127DA/HAMA-MPDA@SS31 (FH-M@S) hydrogel has characteristics of adhesion, superior biocompatibility and mechanical properties which can adapt to irregular wounds at different body sites and provide sustained release of MPDA@SS31 (M@S) NPs. In addition, in a diabetic rat full thickness skin defect model, the FH-M@S hydrogel promoted macrophage M2 polarization, collagen deposition, neovascularization and wound healing. Therefore, the FH-M@S hydrogel exhibits promising therapeutic potential for skin regeneration.

PTT/ PDT-induced Microbial Apoptosis and Wound Healing Depend on Immune Activation and Macrophage Phenotype Transformation

Antibiotics show unsuccessful application in biofilm destruction, which induce chronic infections and emergence of antibiotic resistant bacteria. Photodynamic therapy (PDT) and photothermal therapy (PTT), as widely accepted antimicrobial tools of phototherapy, could effectively activate the immune system and promote the proliferation of wound tissue, thus becoming the most promising therapeutic strategy to replace antibiotics and avoid drug-resistant strains. However, there is no consensus on whether antibacterial and wound healing achieved by PDT/PTT depend not only on the cytotoxic effect of the treatment itself, but also on the activation of host immune system. In this study, CaSiO₃-ClO₂@PDA-ICG nanoparticles (CCPI NPs) were designed as PDT/PTT antimicrobial model material. With the comparison of healing effect between wide-type mice and severely immunodeficient (C-NKG) mice, the dependence of PDT/PTT-induced microbial apoptosis and wound healing on immune activation and macrophage phenotype transformation was explored and verified. Furthermore, the induced phenotypic transformation of macrophages during PDT/PTT treatment was demonstrated to play crucial role in the improvement of epithelial-mesenchymal transformation (EMT). In summary, this study represents great significance for further identifying the role of immune system activation in antibacterial phototherapy and developing new treatment strategies for biofilm-infected wound healing. STATEMENT OF SIGNIFICANCE: A PDT/PTT combination therapy model nanoparticle was established for biofilm-infected wounds. Both microbial apoptosis and wound healing achieved by PDT/PTT combination therapy were highly dependent on the activated immune system, especially the M2 macrophage phenotype. PDT/PTT could promote the polarization of monocytes to the phenotype of M2 macrophages, which promotes EMT behavior of the tissue at the edge of the wound through the secretion of TGF-β1, thus accelerating wound healing.

Insight into the Latest Medical Applications of Nanocellulose

Nanocelluloses (NCs) are appealing nanomaterials that have experienced rapid development in recent years, with great potential in the biomedical field. This trend aligns with the increasing demand for sustainable materials, which will contribute both to an improvement in wellbeing and an extension of human life, and with the demand to keep up with advances in medical technology. In recent years, due to the diversity of their physical and biological properties and the possibility of tuning them according to the desired goal, these nanomaterials represent a point of maximum interest in the medical field. Applications such as tissue engineering, drug delivery, wound dressing, medical implants or those in cardiovascular health are some of the applications in which NCs have been successfully used. This review presents insight into the latest medical applications of NCs, in the forms of cellulose nanocrystals (CNCs), cellulose nanofibers (CNFs) and bacterial nanocellulose (BNC), with an emphasis on the domains that have recently experienced remarkable growth, namely wound dressing, tissue engineering and drug delivery. In order to highlight only the most recent achievements, the presented information is focused on studies from the last 3 years. Approaches to the preparation of NCs are discussed either by top-down (chemical or mechanical degradation) or by bottom-up (biosynthesis) techniques, along with their morphological characterization and unique properties, such as mechanical and biological properties. Finally, the main challenges, limitations and future research directions of NCs are identified in a sustained effort to identify their effective use in biomedical fields.

Tailoring and application of a multi-responsive cellulose nanofibre-based 3D nanonetwork wound dressing

The rapid loss of drugs and the weak curative effects due to cyclical urination are the main reasons why wound heal with difficulty after bladder tumour resection. Here, a bioinspired cellulose nanofibre (CNF)-based magnetic 3D nanonetwork wound dressing with excellent tissue adhesion and biocompatibility is designed by the assembly of pH- and near infrared-responsive CNF nanoskeletons, magnetic switching Fe₃O₄ nanoparticles, and temperature switching Pluronic®F-127. The dressing with high loading capacity for mitomycin and indocyanine green can form a sticky 3D nanonetwork at the wound site and remain for a long time to release drugs through an external magnetic field. Interestingly, the dressing possessed excellent antibacterial activity, bacterial biofilm elimination, T24 tumour cell killing, and wound healing promotion through photothermal, photodynamic, and chemotherapy. Therefore, it has promising application for bladder postoperative infected wound healing to avoid rapid loss of drugs due to cyclical urination.

pH-Responsive wound dressings: advances and prospects

Wound healing is a complex and dynamic process, in which the pH value plays an important role in reflecting the wound status. Wound dressings are materials that are able to accelerate the healing process. Among the multifunctional advanced wound dressings developed in recent years, pH-responsive wound dressings, especially hydrogels, show great potential owing to their unique properties of adjusting their functions according to the wound conditions, thereby allowing the wound to heal in a regulated manner. However, a comprehensive review of pH-responsive wound dressings is lacking. This review summarizes the design strategies and advanced functions of pH-responsive hydrogel wound dressings, including their excellent antibacterial properties and significant pro-healing abilities. Other advanced pH-responsive materials, such as nanofibers, composite films, nanoparticle clusters, and microneedles, are also classified and discussed. Next, the pH-monitoring functions of pH-responsive wound dressings and the related pH indicators are summarized in detail. Finally, the achievements, challenges, and future development trends of pH-responsive wound dressings are discussed.

Multi-crosslinked hydrogels with strong wet adhesion, self-healing, antibacterial property, reactive oxygen species scavenging activity, and on-demand removability for seawater-immersed wound healing

In general, seawater-immersed wounds are associated with tissue necrosis, infection, prolonged healing period, and high mortality because of high salinity, hyperosmosis, and the presence of various pathogenic bacteria in seawater. However, current wound dressings can hardly achieve strong and stable wet adhesion and antibacterial properties, thus limiting their application to seawater-immersed wounds. Here a multifunctional hydrogel (OD/EPL@Fe) comprising catechol-modified oxidized hyaluronic acid (OD), ε-poly-L-lysine (EPL), and Fe³⁺ was prepared primarily through Schiff-base reaction, metal chelation, cation-π, and electrostatic interaction. The hydrogel with high wet adhesion (about 78 kPa) was achieved by combining the mussel-inspired strategy, dehydration effect, and cohesion enhancement, which is higher than that of commercial fibrin glues and cyanoacrylate glues. Meanwhile, the hydrogel can eliminate Marine bacteria (V. vulnificus and P. aeruginosa) and inhibit their biofilm formation. In addition, the hydrogel demonstrated injectability, self-healing, reactive oxygen species scavenging activity, photothermal effect, seawater isolation, on-demand removal, and hemostatic properties. In vivo results showed that the hydrogel had good adhesion to dynamic wounds in a rat neck full-thickness skin wound model. In particular, the hydrogel exhibited antibacterial, anti-inflammatory, and antioxidant properties in a rat seawater-immersed infected wound model and accelerated the reconstruction of skin structure and functions. The results demonstrated that the OD/EPL@Fe would be a potential wound dressing for seawater-immersed wound healing. STATEMENT OF SIGNIFICANCE: A multifunctional OD/EPL@Fe hydrogel has been prepared for the treatment of seawater-immersed wounds. The hydrogel with high wet adhesion was achieved by combining the mussel-inspired strategy, dehydration effect, and cohesion enhancement. The results revealed that the wet adhesion value of hydrogel was about eight times greater than commercial fibrin glues and 1.5 times greater than commercial cyanoacrylate glues. The hydrogel can be easily removed after being sprayed with deferoxamine mesylate. Notably, the inherent antimicrobial material of the hydrogel combined with the photothermal effect can eliminate marine bacteria and inhibit their biofilm formation. Moreover, the hydrogel can accelerate the healing of seawater-immersed infected wound on mice.

Biomaterials releasing drug responsively to promote wound healing via regulation of pathological microenvironment

Wound healing is characterized by complex, orchestrated, spatiotemporal dynamic processes. Recent findings demonstrated suitable local microenvironments were necessities for wound healing. Wound microenvironments include various biological, biochemical and physical factors, which are produced and regulated by endogenous biomediators, exogenous drugs, and external environment. Successful drug delivery to wound is complicated, and need to overcome the destroyed blood supply, persistent inflammation and enzymes, spatiotemporal requirements of special supplements, and easy deactivation of drugs. Triggered by various factors from wound microenvironment itself or external elements, stimuli-responsive biomaterials have tremendous advantages of precise drug delivery and release. Here, we discuss recent advances of stimuli-responsive biomaterials to regulate local microenvironments during wound healing, emphasizing on the design and application of different biomaterials which respond to wound biological/biochemical microenvironments (ROS, pH, enzymes, glucose and glutathione), physical microenvironments (mechanical force, temperature, light, ultrasound, magnetic and electric field), and the combination modes. Moreover, several novel promising drug carriers (microbiota, metal-organic frameworks and microneedles) are also discussed.

Bioabsorbable nano-micelle hybridized hydrogel scaffold prevents postoperative melanoma recurrence

The residual and scattered small tumor tissue or cells after surgery are the main reason for tumor recurrence. Chemotherapy has a powerful ability to eradicate tumors but always accompanied by serious side effects. In this work, tissue-affinity mercapto gelatin (GelS) and dopamine-modified hyaluronic acid (HAD) were employed to fabricate a hybridized cross-linked hydrogel scaffold (HG) by multiple chemical reactions, which could integrate the doxorubicin (DOX) loaded reduction-responsive nano-micelle (PP/DOX) into this scaffold via click reaction to obtain the bioabsorbable nano-micelle hybridized hydrogel scaffold (HGMP). With the degradation of HGMP, PP/DOX was slowly released and formed targeted PP/DOX with degraded gelatin fragments as target molecules, which increased the intracellular accumulation, and inhibited the aggregation of B16F10 cells in vitro. In mouse models, HGMP absorbed the scattered B16F10 cells and released targeted PP/DOX to suppress tumorigenesis. For another, implantation of HGMP at the surgical site reduced the recurrence rate of postoperative melanoma and inhibited the growth of recurrent tumors. Meanwhile, HGMP significantly relieved the damage of free DOX to hair follicle tissue. This bioabsorbable nano-micelle hybridized hydrogel scaffold provided a valuable strategy for adjuvant therapy after tumor surgery.

Phase-change composite filled natural nanotubes in hydrogel promote wound healing under photothermally triggered drug release

It is of great importance to treat a bacterial-infected wound by a smart dressing capable of delivering antibiotics in a smart manner without causing drug resistance. The construction of smart release nanocontainers responsive to near-infrared (NIR) laser irradiation in an on-demand and stepwise way is a promising strategy for avoiding the emergence of multidrug-resistant bacteria. Here, we develop a hydrogel composite made of alginate and nanotubes with an efficient NIR-triggered release of rifampicin and outstanding antibacterial ability. This composite hydrogel is prepared through co-encapsulating antibacterial drug (rifampicin), NIR-absorbing dye (indocyanine green), and phase-change materials (a eutectic mixture of fatty acids) into halloysite nanotubes, followed by incorporation into alginate hydrogels, allowing the in-situ gelation at room temperature and maintaining the integrity of drug-loaded nanotubes. Among them, the eutectic mixture with a melting point of 39 °C serves as the biocompatible phase-change material to facilitate the NIR-triggered drug release. The resultant phase-change material gated-nanotubes exhibit a prominent photothermal efficiency with multistep drug release under laser irradiation. In an in vitro assay, composite hydrogel provides good antibacterial potency against Staphylococcus aureus, one of the most prevalent microorganisms of dangerous gas gangrene. A bacterial-infected rat full-thickness wound model demonstrates that the NIR-responsive composite hydrogel inhibits the bacteria colonization and suppresses the inflammatory response caused by bacteria, promoting angiogenesis and collagen deposition to accelerate wound regeneration. The NIR-responsive composite hydrogel has a great potential as an antibacterial wound dressing functionalized with controlled multistep treatment of the infected sites.

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Phase change material-gated nanocontainer exhibits an efficient NIR-triggered release of drugs.

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Photothermal-responsive hydrogel shows efficient antibacterial properties through the NIR-responsive step-wise antibacterial drug release.

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In vivo, photothermal-responsive hydrogel inhibits bacterial proliferation and effectively suppress the inflammatory response caused by bacteria, thus accelerating bacteria-infected wound regeneration.

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Various types of drugs and biological effectors can be loaded in the nanotubes while the hydrogel matrix can also be regulated to achieve multiple healing functions.

Polydopamine/tannic acid/chitosan/poloxamer 407/188 thermosensitive hydrogel for antibacterial and wound healing

The design and development of smart shape-adaptable wound dressings with superior antimicrobial ability remain a challenge in therapeutic and clinical application. Herein, polydopamine/tannic acid/chitosan/poloxamer 407/188 hydrogel (PTCPP) was prepared with the aim of developing an in situ-formed antibacterial wound dressing with temperature stimulation and near-infrared radiation (NIR) responsive ability. PTCPP possessed injectability, photothermal stability, sustained release properties and cytocompatibility. In vitro antibacterial results showed that the bactericidal rates of PTCPP against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) under NIR irradiation were 99.994 % and 99.91 %, respectively. In vivo experiments, PTCPP can adapt to shape of the wound, showing good adhesion, while promoting wound healing in bacterial infections. Therefore, PTCPP has potential application in the treatment of infectious wounds, and provides a strategic choice for developing antibacterial wound dressing combined with photothermal therapy.

Titanium Dioxide/Chromium Oxide/Graphene Oxide Doped into Cellulose Acetate for Medical Applications

Wound dressings have been designed based on cellulose acetate encapsulated with different concentrations of chromium oxide (Cr₂O₃) and titanium oxide (TiO₂) with/without graphene oxide (GO). This study comprises the structural, morphological, optical, thermal, and biological behavior of chromium oxide/titanium dioxide/graphene oxide-integrated cellulose acetate (CA) films. The CA-based film bond formation was introduced by functional group analysis via Fourier transform infrared (FTIR) spectroscopy. The fabricated Cr₂O₃/TiO₂/GO@CA film SEM micrographs demonstrate transition metal oxides Cr₂O₃ and TiO₂ on a nano-scale. The TiO₂@CA shows the lowest contact angle with 30°. Optically, the refractive index increases from 1.76 for CA to 2.14 for the TiO₂@CA film. Moreover, normal lung cells (A138) growth examination in a function of Cr₂O₃/TiO₂/GO@CA film concentration is conducted, introducing 93.46% with the usage of 4.9 µg/mL. The resulting data showed a promising wound-healing behavior of the CA-based films.

Recent advances in responsive antibacterial materials: design and application scenarios

Bacterial infection is one of the leading causes of death globally, although modern medicine has made considerable strides in the past century. As traditional antibiotics are suffering from the emergence of drug resistance, new antibacterial strategies are of great interest. Responsive materials are appealing alternatives that have shown great potential in combating resistant bacteria and avoiding the side effects of traditional antibiotics. In this review, the responsive antibacterial materials are introduced in terms of stimulus signals including intrinsic (pH, enzyme, ROS, etc.) and extrinsic (light, temperature, magnetic fields, etc.) stimuli. Their biomedical applications in therapeutics and medical devices are then discussed. Finally, the author's perspective of the challenge and the future of such a system is provided.

Coaxial electrospun angiogenic nanofiber wound dressing containing advanced platelet rich-fibrin

Advanced platelet-rich fibrin (A-PRF) provides long-term release of growth factors that potentially accelerate wound healing. In this study, core-shell nanofibrous structure of polyvinyl alcohol (PVA) core and gelatin (Gel) shell containing A-PRF is fabricated through coaxial electrospinning method. PVA/(Gel/A-PRF) core-shell nanofibers had the highest porosity, specific surface area and hydrophilicity among all the studied nanofibers. PVA/(Gel/A-PRF) core-shell nanofibers with a tensile stress of 7.43 ± 0.38 MPa and an elastic modulus of 102.05 ± 9.36 MPa had higher mechanical properties than PVA/Gel/A-PRF and PVA/Gel blend nanofibers. PVA/(Gel/A-PRF) nanofibers had a 47.41 ± 1.97 % degradability over 7 days of immersion in PBS. The release of VEGF and PDGF-AB growth factors from PVA/(Gel/A-PRF) core-shell nanofibers and PVA/Gel/A-PRF blend nanofibers were evaluated. It was shown that L929 cell proliferation and adhesion on PVA/(Gel/A-PRF) core-shell nanofibers were significantly higher than other samples. Also, chicken chorioallantoic membrane (CAM) assay revealed that the highest angiogenic potential among the studied samples related to PVA/(Gel/A-PRF) sample. In vivo studies on a rat model showed wound closure for PVA/(Gel/A-PRF) group was 97.83 ± 2.03 % after 11 days. Histopathological and immunohistochemical examinations approved the acceleration of wound healing by PVA/(Gel/A-PRF) core-shell nanofiber dressing. The results strongly recommend the use of PVA/(Gel/A-PRF) core-shell nanofiber dressing for the repair of full-thickness wounds.

pH-responsive glycodendrimer as a new active targeting agent for doxorubicin delivery

The present study synthesized a new kind of pH-responsive active targeting glycodendrimer (ATGD) for doxorubicin delivery to cancerous cells. First, the glycodendrimer was synthesized based on the cultivation of chitosan dendrons on amine-functionalized, silica-grafted cellulose nanocrystals. Afterward, glycodendrimer was conjugated with folic acid to provide a folate receptor-targeting agent. The response surface method was employed to obtain the optimum conditions for the preparation of doxorubicin-loaded ATGD. The effect of doxorubicin/ATGD ratio, temperature, and pH on doxorubicin loading capacity was evaluated, and high loading capacity was achieved under optimized conditions. After determining doxorubicin release pattern at acidic and physiological pH, ATGD cytotoxicity was surveyed by MTT assay. Based on the results, the loading behavior of doxorubicin onto ATGD was in good agreement with monolayer-physisorption, and drug release was Fickian diffusion-controlled. ATGD could release the doxorubicin much more at acidic pH than physiological pH, corresponding to pH-responsive release behavior. Results of MTT assay confirmed the cytotoxicity of doxorubicin-loaded ATGD in cancer cells, while ATGD (without drug) was biocompatible with no tangible toxicity. These results suggested that ATGD has the potential for the treatment of cancer.

Injectable Thermosensitive Iodine-Loaded Starch-g-poly(N-isopropylacrylamide) Hydrogel for Cancer Photothermal Therapy and Anti-Infection

Although photothermal therapy (PTT) can effectively eliminate tumors, the normal tissues near tumors are inevitably damaged by heat and infected by bacteria, which greatly limits the therapeutic effect. In this work, an injectable thermosensitive hydrogel based on iodine-loaded starch-g-poly(N-isopropylacrylamide) (PNSI) is developed to overcome this problem. FTIR, ¹ H NMR and UV-Vis spectra confirm the graft copolymerization of poly(N-isopropylacrylamide) with starch and the formation of "iodine-starch" complex. TEM images show PNSI polymer self-assembles into regular spherical nanogel with a size of ∼50 nm. The concentrated nanogel dispersion is a sol at room temperature and transforms to hydrogel at body temperature. Under NIR laser irradiation for 10 mins, the ΔT of the nanogel dispersion approachs about 20°C with excellent thermal stability and high cytotoxicity due to the photothermal effect of the "iodine-starch" complex. After intratumor injection, this injectable hydrogel efficiently inhibites the tumor growth using 808 nm laser irradiation. Furthermore, it can also suppress S. aureus infection in the wound post PTT due to the release of iodine, which promotes wound healing. Therefore, this injectable thermosensitive "iodine-starch" composite hydrogel with advantages of good biocompatible and easy preparation possesses potential application for tumor photothermal therapy and anti-bacterial infection. This article is protected by copyright. All rights reserved.

Skin-like wound dressings with on-demand administration based on in situ peptide self-assembly for skin regeneration

Burn injuries without the normal skin barrier usually cause skin wound infections, and wound dressings are necessary. Although various dressings with antibacterial ability have already been developed, the biosafety and administration mode are still bottleneck problems for further application. Herein, we designed skin-like wound dressings based on silk fibroin (SF), which are modified with the gelatinase-cleavable self-assembled/antibacterial peptide (GPLK) and epidermal growth factor (EGF). When a skin wound is infected, the gelatinase over-secreted by bacteria can cut the GPLK peptides, leading to the in situ self-assembly of peptides and the resultant high-efficiency sterilization. Compared with the commercial antibacterial dressing, the SF-GPLK displayed a faster wound healing rate. When a skin wound is not infected, the GPLK peptides remain in the SF, realizing good biosafety. Generally, the EGF can be released to promote wound healing and skin regeneration in both cases. Therefore, skin-like SF-GPLK wound dressings with on-demand release of antibacterial peptides provide a smart administration mode for clinical wound management and skin regeneration.

Preparation of coated paper reinforced by a blend of anionic-starch-based nanocellulose/chitosan and its properties

Carboxylated cellulose nanocrystal whisker (C-CNC) and chitosan (CTS) were used to blend and reinforce anionic starch (AS) to prepare a paper-coating agent, AS-CNC-CTS, which was coated on one side of the surface of offset paper and kraft paper. Scanning electron microscopy (SEM) showed that the AS-CNC-CTS coating agent can form a layer of dense film on the paper surface and fill the surface pores. And also, owing to the irregular pore structure of the paper, the coating agent penetrated the pores to different degrees. The structure and mechanical properties of the coated paper were analyzed using a Fourier infrared spectrometer, computer-controlled paper-tearing tester and paper tensile strength test machine. Peptide bonding interaction between C-CNC and CTS, hydrogen bonding between C-CNC and CTS, C-CNC and AS, C-CNC and paper fibers, as well as electrostatic attraction between acidified CTS and AS were found. Moreover, the coating agent also had good antibacterial properties, and no mold spots formed throughout the observation period (60d). The gas-barrier properties and oil resistance of the coated paper were further studied using a paper and paperboard air permeability tester and a paper oil-permeability tester. Results showed that the coating agent can significantly enhance the gas-barrier properties and oil resistance of paper. Furthermore, with increased C-CNC content in the coating agent, its barrier properties gradually increased. This finding indicated that the coating preparation had no effect on the crystal region of C-CNC.

Carboxylated cellulose nanocrystal whisker (C-CNC) and chitosan (CTS) were used to blend and reinforce anionic starch (AS) to prepare a paper-coating agent, AS-CNC-CTS, which was coated on one side of the surface of offset paper and kraft paper.