Microfluidic electrospray photo-crosslinkable κ-Carrageenan microparticles for wound healing

Magnetic structural color microspheres for the multiplex detection of acute kidney injury biomarkers

BACKGROUND

Acute kidney injury (AKI) is a frequent acute condition that features sharp loss of kidney functions and often leads to severe situations such as end-stage renal disease and even death. The incidence and mortality of AKI in hospitalized patients are high worldwide, and one of the reasons for this poor prognosis is the inability to diagnose AKI promptly. The sensitive and specific assay of biomarkers is considered a promising method for early diagnosis of AKI.

RESULTS

We designed a magnetic-responsive structural colored inverse opal hydrogel microspheres (IOHMs) for the multiplex detection of cystatin C (CysC) and neutrophil gelatinase-associated lipocalin (NGAL), which are two early biomarkers of AKI. The microsphere possessed structural colors for encoding and directional motion ability for improved detection sensitivity and separation efficiency, showing the detection ranges of CysC and NGAL in 10-5000 ng/mL and 10-1000 ng/mL, respectively.

SIGNIFICANCE

The method's accuracy and reliability were consistent with commonly used enzyme-linked immunosorbent assay methods. Therefore, these magnetic IOHMs have a promising application for early AKI diagnosis.

Recent development of micro-nano carriers for oral antineoplastic drug delivery

Chemotherapy is widely recognized as a highly efficacious modality for cancer treatment, involving the administration of chemotherapeutic agents to target and eradicate tumor cells. Currently, oral administration stands as the prevailing and widely utilized method of delivering chemotherapy drugs. However, the majority of anti-tumor medications exhibit limited solubility and permeability, and poor stability in harsh gastrointestinal environments, thereby impeding their therapeutic efficacy for chemotherapy. Therefore, more and more micro-nano drug delivery carriers have been developed and used to effectively deliver anti-cancer drugs, which can overcome physiological barriers, facilitate oral administration, and ultimately improve drug efficacy. In this paper, we first discuss the effects of various biological barriers on micro-nano drug carriers and oral administration approach. Then, the development of micro-nano drug carriers based on various biomedical components, such as micelles, dendrimers, hydrogels, liposomes, inorganic nanoparticles, etc. were introduced. Finally, the current dilemma and the potential of oral drug delivery for clinical treatment were discussed. The primary objective of this review is to introduce various oral delivery methods and serve as a point of reference for the advancement of novel oral delivery carriers, with the ultimate goal of informing the development of future clinical applications.

Material-driven immunomodulation and ECM remodeling reverse pulmonary fibrosis by local delivery of stem cell-laden microcapsules

Recent progress in stem cell therapy has demonstrated the therapeutic potential of intravenous stem cell infusions for treating the life-threatening lung disease of pulmonary fibrosis (PF). However, it is confronted with limitations, such as a lack of control over cellular function and rapid clearance by the host after implantation. In this study, we developed an innovative PF therapy through tracheal administration of microfluidic-templated stem cell-laden microcapsules, which effectively reversed the progression of inflammation and fibrotic injury. Our findings highlight that hydrogel microencapsulation can enhance the persistence of donor mesenchymal stem cells (MSCs) in the host while driving MSCs to substantially augment their therapeutic functions, including immunoregulation and matrix metalloproteinase (MMP)-mediated extracellular matrix (ECM) remodeling. We revealed that microencapsulation activates the MAPK signaling pathway in MSCs to increase MMP expression, thereby degrading overexpressed collagen accumulated in fibrotic lungs. Our research demonstrates the potential of hydrogel microcapsules to enhance the therapeutic efficacy of MSCs through cell-material interactions, presenting a promising yet straightforward strategy for designing advanced stem cell therapies for fibrotic diseases.

Dexamethasone loaded DNA scavenger nanogel for systemic lupus erythematosus treatment

Lupus nephritis (LN) poses a severe risk for individuals with systemic lupus erythematosus (SLE), prompting extensive research into targeted delivery systems capable of modulating immune responses and clearing cell-free DNA (cfDNA). Here, we propose a novel renal homing nanogel that acts as a cfDNA scavenger and a dexamethasone (DXM) delivery carrier for LN treatment. Based on the generation 3 polylysine dendrimers, the created cationic nanogels (G3DSP) exhibit minimal toxicity and outstanding DXM loading efficiency. Our studies confirm that these nanogels can competitively bind with anionic cfDNA in vitro, leading to the suppression of toll-like receptor 9 (TLR9) activation. When administered systemically to MRL/lpr mice, the nanogels preferentially localize to and are retained in the inflamed kidneys, releasing their payload in response to reactive oxygen species (ROS), therefore effectively ameliorating SLE symptoms. Consequently, G3DSP nanogels emerge as a promising effective combined therapy for LN, minimizing cfDNA accumulation in vital organs and delivering immunomodulatory benefits through DXM.

Bioorthogonal Janus microparticles for photothermal and chemo-therapy

Bioorthogonal chemistry, recognized as a highly efficient tool in chemical biology, has shown significant value in cancer treatment. The primary objective is to develop efficient delivery strategies to achieve enhanced bioorthogonal drug treatment for tumors. Here, Janus microparticles (JMs) loaded with cyclooctene-modified doxorubicin prodrug (TCO-DOX) and tetrazine-modified indocyanine green (Tz-ICG) triggers are reported. Besides activating TCO-DOX, Tz-ICG is also a photothermal agent used in photothermal therapy (PTT), enabling the simultaneous use of biorthogonal chemotherapy and PTT. Additionally, the DOX could be significantly reduced in systemic toxicity with the modification of cyclooctene. Thus, the developed drug-carrying JMs system exhibits effective tumor cell killing in vitro and effectively inhibits tumor local progress and distant lung metastasis after postoperative treatment with good safety. These results demonstrate that the prepared JMs provide a paradigm for bioorthogonal prodrug activation and localized delivery, and hold great promise for cancer therapy as well as other related applications.

The hyaluronic acid-gelatin hierarchical hydrogel for osteoporotic bone defect repairment

Osteoporotic bone defects are serious medical problems due to their sparse bone structure, difficulty in restoration and reconstruction, and high recurrence rates, which also result in heavy economic and social burdens. Herein, we developed a hierarchical hydrogel composed of alendronate sodium (AS)/Mg2+-loaded inverse opal methylpropenylated gelatin (GelMA) hydrogel microspheres (IOHM-AS-Mgs) within methylpropenylated poly(hyaluronic acid) (HAMA) for osteoporotic bone defect treatment. The IOHM-AS-Mgs displayed good cytocompatibility and cell adhesion and strongly stimulated osteogenesis at the transcriptomic and protein levels. When this treatment was applied to the osteoporotic bone defect area, HAMA was used to fix the microspheres. The results of the microcomputed tomography (micro-CT) and histological analyses indicated that the hierarchical hydrogel had the best therapeutic effect. Therefore, this hydrogel is a new candidate for osteoporotic bone defect treatment.

Research Progress on Injectable Microspheres as New Strategies for the Treatment of Osteoarthritis Through Promotion of Cartilage Repair

Osteoarthritis (OA) is a degenerative disease caused by a variety of factors with joint pain as the main symptom, including fibrosis, chapping, ulcers, and loss of cartilage. Traditional treatment can only delay the progression of OA, and classical delivery system have many side effects. In recent years, microspheres have shown great application prospects in the field of OA treatment. Microspheres can support cells, reproduce the natural tissue microenvironment in vitro and in vivo, and are an efficient delivery system for the release of drugs or biological agents, which can promote cell proliferation, migration, and differentiation. Thus, they have been widely used in cartilage repair and regeneration. In this review, preparation processes, basic materials, and functional characteristics of various microspheres commonly used in OA treatment are systematically reviewed. Then it is introduced surface modification strategies that can improve the biological properties of microspheres and discussed a series of applications of microsphere functionalized scaffolds in OA treatment. Finally, based on bibliometrics research, the research development, future potential, and possible research hotspots of microspheres in the field of OA therapy is systematically and dynamically evaluated. The comprehensive and systematic review will bring new understanding to the field of microsphere treatment of OA.

Nanoengineered oxygen-releasing polymeric scaffold with sustained release of dexamethasone for bone regeneration

Maintaining the continuous oxygen supply and proper cell growth before blood vessel ingrowth at the bone defect site are considerably significant issues in bone regeneration. Oxygen-producing scaffolds can supply oxygen and avoid hypoxia leading to expedited bone regeneration. Herein, first oxygen-producing calcium peroxide nanoparticles (CPO NPs) are synthesized, and subsequently, the various amounts of synthesized CPO NPs (0.1, 0.5, and 1 wt/v%) loaded in the scaffold composite, which is developed by simple physical blending of chitosan (CS) and polycaprolactone (PCL) polymers. To deliver the synergistic therapeutic effect, dexamethasone (DEX), known for its potential anti-inflammatory and osteogenic properties, is loaded into the nanocomposite scaffolds. The extensive physicochemical characterizations of nanocomposite scaffolds confirm the successful loading of CPO NPs, adequate porous morphology, pore size, hydrophilicity, and biodegradability.In vitro, biological studies support the antibacterial, hemocompatible, and cytocompatible (MG-63 and MC3T3-E1 cells) nature of the material when tested on respective cells. Field emission scanning electron microscopy and energy-dispersive x-ray spectroscopy confirm the successful biomineralization of the scaffolds. Scaffolds also exhibit the sustained release of DEX and efficient protein adsorption. This study revealed that a nanoengineered scaffold loaded with CPO NPs (PCL/CS/DEX/CPO 3) is a suitable candidate for bone tissue regeneration.

Sprayable Multifunctional Black Phosphorus Hydrogel with On-Demand Removability for Joint Skin Wound Healing

Wound healing remains a critical challenge in regenerative engineering. Great efforts are devoted to develop functional patches for wound healing. Herein, a novel sprayable black phosphorus (BP)-based multifunctional hydrogel with on-demand removability is presented as a joints' skin wound dressing. The hydrogel is facilely prepared by mixing dopamine-modified oxidized hyaluronic acid, cyanoacetategroup-functionalized dextran containing black phosphorus, and the catalyst histidine. The catechol-containing dopamine can not only enhance tissue adhesiveness, but also endow the hydrogel with antioxidant capacity. In addition, benefiting from the photothermal conversion ability of the BP and thermally reversible performance of the formed C═C double bonds between aldehyde groups and cyanoacetate groups, the resulting hydrogel displays excellent antibacterial performance and on-demand dissolving ability under NIR irradiation. Moreover, by loading vascular endothelial growth factor into the hydrogel, the promoted migration and angiogenesis effects of endothelial cells can also be achieved. Based on these features, it is demonstrated that such sprayable BP hydrogels can effectively facilitate joint wounds healing by accelerating angiogenesis, alleviating inflammation, and improving wound microenvironment. Thus, it is believed that this NIR-responsive removable BP hydrogel dressing will put forward an innovative concept in designing wound dressings.

Designing Bioorthogonal Reactions for Biomedical Applications

Bioorthogonal reactions are a class of chemical reactions that can be carried out in living organisms without interfering with other reactions, possessing high yield, high selectivity, and high efficiency. Since the first proposal of the conception by Professor Carolyn Bertozzi in 2003, bioorthogonal chemistry has attracted great attention and has been quickly developed. As an important chemical biology tool, bioorthogonal reactions have been applied broadly in biomedicine, including bio-labeling, nucleic acid functionalization, drug discovery, drug activation, synthesis of antibody-drug conjugates, and proteolysis-targeting chimeras. Given this, we summarized the basic knowledge, development history, research status, and prospects of bioorthogonal reactions and their biomedical applications. The main purpose of this paper is to furnish an overview of the intriguing bioorthogonal reactions in a variety of biomedical applications and to provide guidance for the design of novel reactions to enrich bioorthogonal chemistry toolkits.

Application of Nondegradable Synthetic Materials for Tendon and Ligament Injury

Tendon and ligament injuries, prevalent requiring surgical intervention, significantly impact joint stability and function. Owing to excellent mechanical properties and biochemical stability, Nondegradable synthetic materials, including polyethylene terephthalate (PET) and polytetrafluoroethylene (PTFE), have demonstrated significant potential in the treatment of tendon and ligament injuries. These above materials offer substantial mechanical support, joint mobility, and tissue healing promotion of the shoulder, knee, and ankle joint. This review conclude the latest development and application of nondegradable materials such as artificial patches and ligaments in tendon and ligament injuries including rotator cuff tears (RCTs), anterior cruciate ligament (ACL) injuries, and Achilles tendon ruptures.

Alginate/gum arabic-based biomimetic hydrogel enriched with immobilized nerve growth factor and carnosine improves diabetic wound regeneration

Diabetic foot ulcers (DFUs) often remain untreated because they are difficult to heal, caused by reduced skin sensitivity and impaired blood vessel formation. In this study, we propose a novel approach to manage DFUs using a multifunctional hydrogel made from a combination of alginate and gum arabic. To enhance the healing properties of the hydrogel, we immobilized nerve growth factor (NGF), within specially designed mesoporous silica nanoparticles (MSN). The MSNs were then incorporated into the hydrogel along with carnosine (Car), which further improves the hydrogel's therapeutic properties. The hydrogel containing the immobilized NGF (SiNGF) could control the sustain release of NGF for >21 days, indicating that the target hydrogel (AG-Car/SiNGF) can serve as a suitable reservoir managing diabetic wound regeneration. In addition, Car was able to effectively reduce inflammation and significantly increase angiogenesis compared to the control group. Based on the histological results obtained from diabetic rats, the target hydrogel (AG-Car/SiNGF) reduced inflammation and improved re-epithelialization, angiogenesis, and collagen deposition. Specific staining also confirmed that AG-Car/SiNGF exhibited improved tissue neovascularization, transforming growth factor-beta (TGFβ) expression, and nerve neurofilament. Overall, our research suggests that this newly developed composite system holds promise as a potential treatment for non-healing diabetic wounds.

Fabrication of injectable antibiotic-loaded apatitic bone cements with prolonged drug delivery for treating post-surgery infections

Antibiotic-loaded bioactive bone substitutes are widely used for treating various orthopedic diseases and prophylactically to avoid post implantation infection. Calcium deficient hydroxyapatite (also known as apatitic bone cement) is a potential bioactive bone substitute in orthopedics due to its chemical composition similar to that of natural bone minerals. In this study, fabrication of mannitol (a solid porogen) incorporated injectable synthetic (Syn) and eggshell derived (ESD) apatitic bone cements loaded with antibiotics (gentamicin/meropenem/ rifampicin/vancomycin) was investigated. The release kinetics of the antibiotics were studied by fitting them with different kinetic models. All the antibiotics-loaded apatitic bone cements set within clinically accepted setting time (20 ± 2 min) and with good injectability (>70%). The antibiotics released from these bone cements were found to be controlled and sustained throughout the study time. Weibull and Gompertz (applies in least initial burst and sustain drug release rate models) were the best models to predict the release behavior. They cements had acceptable compressive strength (6-10 MPa; in the range of trabecular bone) and were biodegradable (21%-27% within 12 weeks of incubation) in vitro in simulated body fluids at physiological conditions. These bone cements showed excellent antibacterial activity from day 1 onwards and no bacterial colony was found from day 3 onwards. The viability of MG63 cells in vitro after 72 h was significantly higher after 24 h (i.e., ~110%). The cells were well attached and spread over the surface of the cements with extended morphology. The ESD antibiotic-loaded apatitic bone cements showed better injectability, degradation and cytocompatibility compared when compared to Syn antibiotic-loaded apatitic bone cements. Thus, we believe that the ESD antibiotic-loaded apatitic bone cements are suitable as potential injectable bone substitutes to avoid post-operative implant associated and other acute or chronic bone infections.

Multi-Bioinspired MOF Delivery Systems from Microfluidics for Tumor Multimodal Therapy

Metal-organic framework (MOF)-based drug delivery systems have demonstrated values in oncotherapy. Current research endeavors are centralized on the functionality enrichment of featured MOF materials with designed versatility for synergistic multimodal treatments. Here, inspired by the multifarious biological functions including ferroptosis pattern, porphyrins, and cancer cell membrane (CCM) camouflage technique, novel multi-biomimetic MOF nanocarriers from microfluidics are prepared. The Fe3+ , meso-tetra(4-carboxyphenyl)porphine and oxaliplatin prodrug are incorporated into one MOF nano-system (named FeTPt), which is further cloaked by CCM to obtain a "Trojan Horse"-like vehicle (FeTPt@CCM). Owing to the functionalization with CCM, FeTPt@CCM can target and accumulate at the tumor site via homologous binding. After being internalized by cancer cells, FeTPt@CCM can be activated by a Fenton-like reaction as well as a redox reaction between Fe3+ and glutathione and hydrogen peroxide to generate hydroxyl radical and oxygen. Thus, the nano-platform effectively initiates ferroptosis and improves photodynamic therapy performance. Along with the Pt-drug chemotherapy, the nano-platform exhibits synergistic multimodal actions for inhibiting cancer cell proliferation in vitro and suppressing tumor growth in vivo. These features indicate that such a versatile biomimetic MOF delivery system from microfluidics has great potential for synergistic cancer treatment.

Microvascular endothelial cells derived from spinal cord promote spinal cord injury repair

Neural regeneration after spinal cord injury (SCI) closely relates to the microvascular endothelial cell (MEC)-mediated neurovascular unit formation. However, the effects of central nerve system-derived MECs on neovascularization and neurogenesis, and potential signaling involved therein, are unclear. Here, we established a primary spinal cord-derived MECs (SCMECs) isolation with high cell yield and purity to describe the differences with brain-derived MECs (BMECs) and their therapeutic effects on SCI. Transcriptomics and proteomics revealed differentially expressed genes and proteins in SCMECs were involved in angiogenesis, immunity, metabolism, and cell adhesion molecular signaling was the only signaling pathway enriched of top 10 in differentially expressed genes and proteins KEGG analysis. SCMECs and BMECs could be induced angiogenesis by different stiffness stimulation of PEG hydrogels with elastic modulus 50-1650 Pa for SCMECs and 50-300 Pa for BMECs, respectively. Moreover, SCMECs and BMECs promoted spinal cord or brain-derived NSC (SNSC/BNSC) proliferation, migration, and differentiation at different levels. At certain dose, SCMECs in combination with the NeuroRegen scaffold, showed higher effectiveness in the promotion of vascular reconstruction. The potential underlying mechanism of this phenomenon may through VEGF/AKT/eNOS- signaling pathway, and consequently accelerated neuronal regeneration and functional recovery of SCI rats compared to BMECs. Our findings suggested a promising role of SCMECs in restoring vascularization and neural regeneration.

An oral polyphenol host-guest nanoparticle for targeted therapy of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a global public health challenge that affects millions of people. Current medical treatments for IBD are not fully effective and may cause undesirable side effects on patients. Thus, there is an urgent need for safe, simple, and efficacious strategies to treat IBD in clinical settings. Here, we develop an oral polyphenol nanoparticle (PDT) by assembling dexamethasone sodium phosphate (DSP)-loaded poly-β-cyclodextrin with tannic acid via host-guest interactions for treating IBD. This one-step assembly process is rapid (within 10 s), reproducible, and free of harmful chemical agents, which can facilitate its clinical translation. PDT is negatively charged due to the three components, which enable it to specifically target the positively charged inflamed colonic mucosa through electrostatic attraction, thus localizing the drug at the inflamed site to reduce systemic exposure and side effects. Furthermore, PDT exhibits a strong reactive oxygen species (ROS)-scavenging ability derived from the tannic acid component, which can alleviate ROS-mediated inflammatory responses and ameliorate IBD symptoms. Compared with free DSP, PDT demonstrates sustained DSP release behavior in vitro and in vivo, as well as enhanced therapeutic efficacy in a colitis mouse model. These results suggest that PDT might be a potential therapeutic agent for the treatment of IBD. Moreover, this facile polyphenol host-guest assembly strategy may provide a promising drug-delivery platform for treating various diseases STATEMENT OF SIGNIFICANCE: To develop safe and effective treatments for inflammatory bowel disease (IBD), we have designed an oral polyphenol nanoparticle (PDT) using the host-guest assembly of dexamethasone sodium phosphate (DSP)-loaded poly-β-cyclodextrin with tannic acid. Through in vitro and in vivo experiments, PDT has demonstrated remarkable inflammation-targeting, ROS-scavenging, and anti-inflammatory properties, along with sustained release of DSP. Moreover, in an IBD mouse model, PDT has shown significantly improved therapeutic efficacy compared to free DSP. The host-guest assembly strategy employed for PDT is noteworthy for its rapidity, reproducibility, and safety due to the absence of harmful chemicals, holding great promise for designing a diverse range of nanomedicines customized for treating various diseases.

Cell Electrospinning: a Review of Materials and Methodologies for Biofabrication

The process of electrohydrodynamic living cell microencapsulation inside a scaffold during the electrospinning (ES) process is called cell electrospinning (CE). Several studies demonstrate the feasibility of using cell electrospinning for biomedical applications, allowing for the direct biofabrication of living cells to be encapsulated in fibers for the formation of active biological scaffolds. In this review, a comprehensive overview of the materials and methodologies used in cell electrospinning, as well as their biomedical application in tissue engineering, is provided. Cell ES represents an innovative technique for automated application in regenerative medicine.

Electrospinning and Cell Fibers in Biomedical Applications

Human body tissues such as muscle, blood vessels, tendon/ligaments, and nerves have fiber-like fascicle morphologies, where ordered organization of cells and extracellular matrix (ECM) within the bundles in specific 3D manners orchestrates cells and ECM to provide tissue functions. Through engineering cell fibers (which are fibers containing living cells) as living building blocks with the help of emerging "bottom-up" biomanufacturing technologies, it is now possible to reconstitute/recreate the fiber-like fascicle morphologies and their spatiotemporally specific cell-cell/cell-ECM interactions in vitro, thereby enabling the modeling, therapy, or repair of these fibrous tissues. In this article, a concise review is provided of the "bottom-up" biomanufacturing technologies and materials usable for fabricating cell fibers, with an emphasis on electrospinning that can effectively and efficiently produce thin cell fibers and with properly designed processes, 3D cell-laden structures that mimic those of native fibrous tissues. The importance and applications of cell fibers as models, therapeutic platforms, or analogs/replacements for tissues for areas such as drug testing, cell therapy, and tissue engineering are highlighted. Challenges, in terms of biomimicry of high-order hierarchical structures and complex dynamic cellular microenvironments of native tissues, as well as opportunities for cell fibers in a myriad of biomedical applications, are discussed.

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.

Amyloid Fibril and Clay Nanosheet Dual-Nanoengineered DNA Dynamic Hydrogel for Vascularized Bone Regeneration

Dynamic hydrogels have attracted enormous interest for bone tissue engineering as they demonstrate reversible mechanics to better mimic biophysical cues of natural extracellular matrix (ECM) compared to traditional static hydrogels. However, the facile development of therapeutic dynamic hydrogels that simultaneously recapitulate the filamentous architecture of the ECM of living tissues and induce both osteogenesis and angiogenesis to augment vascularized bone regeneration remains challenging. Herein, we report a dual nanoengineered DNA dynamic hydrogel developed through the supramolecular coassembly of amyloid fibrils and clay nanosheets with DNA strands. The nanoengineered ECM-like fibrillar hydrogel network is facilely formed without a complicated and tedious molecular synthesis. Amyloid fibrils together with clay nanosheets synergistically enhance the mechanical strength and stability of the dynamic hydrogel and, more remarkably, endow the matrix with an array of tunable features, including shear-thinning, injectability, self-healing, self-supporting, and 3D printable properties. The QK peptide is further chemically grafted onto amyloid fibrils, and its sustainable release from the hydrogel matrix stimulates the tube formation and migration with human umbilical vein endothelial cells. Meanwhile, the nanoengineered hydrogel matrix promotes osteogenic differentiation of bone marrow mesenchymal stem cells due to the sustainable release of Si4+ and Mg2+ derived from clay nanosheets. Furthermore, the manipulation of enhanced vascularized bone regeneration by the dynamic hydrogel is revealed in a rat cranial bone defect model. This dual nanoengineered strategy envisions great promise in developing therapeutic dynamic hydrogels for improved and customizable bone regeneration.

Near-IR-Regulated Composite Hydrogel with Real-Time Infection Monitoring and a Combined Antibacterial Effect for Efficient Wound Management

Chronic wounds induced by bacterial infection have seriously affected the health of people in the world. So, it is meaningful to develop a novel strategy with real-time infection monitoring and excellent antibacterial performance for enhancing wound management. Herein, we constructed a composite hydrogel by loading the pH indicator bromothymol blue (BTB) and gold nanocages containing 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride (Au NCs@AIPH) into a polyacrylamide-co-poly(acrylic anhydride-modified oxidized sodium alginate) (PAM-co-PAOSA) hydrogel. In vitro and in vivo experimental results demonstrated that the composite hydrogel could effectively detect bacteria and diagnose the infection status of a wound in real time by showing visible color changes. In addition, the composite hydrogel containing Au NCs@AIPH possessed an excellent photothermal effect under near-IR (NIR) laser irradiation. The photothermal effect further activated AIPH to generate toxic free radicals to form combined antibacterial therapy for accelerating wound healing. Moreover, the composite hydrogel showed great biocompatibility. Therefore, the multifunctional hydrogel provided a novel wound management strategy for bacterial infection diagnosis and combined therapy in an infected wound.

M2 macrophage-derived exosome-encapsulated microneedles with mild photothermal therapy for accelerated diabetic wound healing

Due to local overactive inflammatory response and impaired angiogenesis, current treatments for diabetic wounds remain unsatisfactory. M2 macrophage-derived exosomes (MEs) have shown considerable potential in biomedical applications, especially since they have anti-inflammatory properties that modulate macrophage phenotypes. However, exosome-based strategies still have limitations, such as short half-lives and instability. Herein, we develop a double-layer microneedle-based wound dressing system (MEs@PMN) by encapsulating MEs in the needle tips and polydopamine (PDA) nanoparticles in backing layer to simultaneously suppress inflammation and improve angiogenesis at the wound site. In vitro, released MEs increased macrophage polarization towards the M2 phenotype. In addition, mild heat (40 ​°C) generated by the photosensitive PMN backing layer contributed to improved angiogenesis. More importantly, MEs@PMN also showed promising effects in diabetic rats. The uncontrolled inflammatory response at the wound site was inhibited by MEs@PMN during a 14-day period; in addition, MEs and the photothermal effects produced by PMN provided a combined proangiogenic effect by improving the expression of CD31 and vWF. Collectively, this study provides a simple and efficient cell-free strategy for suppressing inflammation and promoting vascular regeneration to treat diabetic wounds.

Plant-Derived Polyphenol and LL-37 Peptide-Modified Nanofibrous Scaffolds for Promotion of Antibacterial Activity, Anti-Inflammation, and Type-H Vascularized Bone Regeneration

The regeneration of oral tissues is a challenging clinical problem because of the complex microbial and biological stress environments. Electrospun fibrous scaffolds have attracted significant interest as effective barrier membranes for guided bone regeneration (GBR); however, no mature strategy yet exists for the surface modification of fibers to provide versatility to satisfy clinical requirements. This study demonstrated a practical biosafety strategy: the combined use of plant polyphenols and LL-37 peptides to modify the fiber surface to endow the fibrous scaffold with antimicrobial activity, immunoregulation, and vascularized bone regeneration. We confirmed that the LL-37 peptides interacted with tannic acid (TA) through noncovalent bonds through experiments and molecular docking simulation analysis. In vitro experiments showed that the TA coating imparted strong antibacterial properties to the fibrous scaffold, but it also caused cytotoxicity. The grafting of LL-37 peptide promoted the spreading, migration, and osteogenic differentiation of mesenchymal stem cells and was also conducive to the M2 polarization of RAW264.7 cells. In vivo experiments further verified that the LL-37 peptide-grafted fibrous scaffold significantly enhanced angiogenesis, anti-inflammatory effects, and type-H vascularized bone regeneration. Overall, the fibrous scaffold modified by the LL-37 peptide through TA grafting has significant potential for GBR applications.

Polysaccharide-based hydrogels for drug delivery and wound management: a review

INTRODUCTION

Polysaccharide-based hydrogels (PBHs) offer several advantages over their synthetic counterparts. Their natural origin contributes to their nontoxicity, high biocompatibility, and in vivo biodegradability. Their properties can be tuned finely to obtain hydrogels with desired mechanical, structural, and chemical properties.

AREAS COVERED

Such versatile characteristics have potentiated the use of PBHs for the delivery of drugs, vaccines, protein and peptide therapeutics, genes, cells, probiotics, bacteriophages, and other therapeutic agents. Recent advances in hydrogel-based formulations such as nanogels, microgels, microneedles, hydrogel beads, nanocarrier-loaded hydrogels, and complexation hydrogels have enabled the precise delivery of a wide range of therapeutics. This review aims to give a holistic overview of hydrogels in the delivery of a variety of therapeutics through different routes.

EXPERT OPINION

PBHs have been used to enable the oral delivery of vaccines and other biologicals, thereby allowing self-administration of life-saving vaccines during public health emergencies. There is a lack of commercialized wound dressings for the treatment of chronic wounds. PBH-based wound dressings, especially those based on chitosan and loaded with actives and growth factors, have the potential to help in the long-term treatment of such wounds. Recent developments in the 3D printing of hydrogels can enable the quick and large-scale production of drug-loaded hydrogels.

Natural Materials for 3D Printing and Their Applications

In recent years, 3D printing has gradually become a well-known new topic and a research hotspot. At the same time, the advent of 3D printing is inseparable from the preparation of bio-ink. Natural materials have the advantages of low toxicity or even non-toxicity, there being abundant raw materials, easy processing and modification, excellent mechanical properties, good biocompatibility, and high cell activity, making them very suitable for the preparation of bio-ink. With the help of 3D printing technology, the prepared materials and scaffolds can be widely used in tissue engineering and other fields. Firstly, we introduce the natural materials and their properties for 3D printing and summarize the physical and chemical properties of these natural materials and their applications in tissue engineering after modification. Secondly, we discuss the modification methods used for 3D printing materials, including physical, chemical, and protein self-assembly methods. We also discuss the method of 3D printing. Then, we summarize the application of natural materials for 3D printing in tissue engineering, skin tissue, cartilage tissue, bone tissue, and vascular tissue. Finally, we also express some views on the research and application of these natural materials.

Dexamethasone loaded injectable, self-healing hydrogel microspheresbased on UPy-functionalized Gelatin/ZnHAp physical network promotes bone regeneration

Biopolymer-based injectable hydrogels provide great potential as bone tissue engineering (BTE) scaffolds on account of biocompatibility, and pore interconnectivity that enables delivery of cells and/or signaling molecules for bone repair. Recently, Gelatin hydrogels based on H-bonds were considered in response to concerns around the chemical crosslinking agents. In this study, a self-healing gelatin hydrogel with remarkable compressive and self-healing properties was prepared via formation of quadruple hydrogen bonds between ureidopyrimidinon functional groups, which were substituted on NH₂ groups of gelatin(GelUPy). Degree of substitution controls properties of the resulting hydrogel from a shape- memory hydrogel (100% substitution), to a hydrogel (about 80%), to this self-healing hydrogel (about 40%). We report a strategy that adopts an emulsion synthesis approach to delivery of dexamethasone and Ca/Zn ions from injectable self-healing GelUPy hydrogel (GelUPy-ZnHApUPy-DEX), to induce osteogenic differentiation of adipose-derived stem cells, in vitro, and enhance bone regeneration in a cranial bone defect in a rat model. We show that key properties of the composite hydrogels, including mechanical properties, and release behavior of DEX are a match to the requirements of BTE. Overall, our results demonstrate that this self-healing gelatin approach is a promising strategy to enhance bone regeneration through a minimally invasive procedure.

Astaxanthin Activated the Nrf2/HO-1 Pathway to Enhance Autophagy and Inhibit Ferroptosis, Ameliorating Acetaminophen-Induced Liver Injury

Acetaminophen (APAP)-induced liver injury (AILI) is a common liver disease in clinical practice. Only one clinically approved drug, N-acetylcysteine (NAC), for the treatment of AILI is available in clinics, but novel treatment strategies are still needed due to the complicated pathological changes of AILI and the side effects of NAC. Here, we found that astaxanthin (ASX) can prevent AILI through the Nrf2/HO-1 pathway. After treatment with ASX, there was a positive activation of the Nrf2/HO-1 pathway in AILI models both in vivo and in vitro accompanied by enhanced autophagy and reduced ferroptosis. In APAP-challenged L02 liver cells, ASX reduced autophagy and enhanced apoptosis of the cells. Furthermore, we developed ASX-loaded hollow mesoporous silica nanoparticles (HMSN@ASX) to improve the aqueous solubility of ASX and targeted delivery of ASX to the liver and then significantly improve the therapeutic effects. Taken together, we found that ASX can protect against AILI by activating the Nrf2/HO-1 pathway, which mainly affects oxidative stress, autophagy, and ferroptosis processes, and the HMSN@ASX nanosystem can target the liver to enhance the treatment efficiency of AILI.

Nanoarchitectonics of Cartilage-Targeting Hydrogel Microspheres with Reactive Oxygen Species Responsiveness for the Repair of Osteoarthritis

Clinically, intra-articular administration can hardly achieve the truly targeted therapy, and the drugs are usually insufficient to show local and long-term therapeutic effects because of their rapid clearance. Herein, inspired by the phenomenon that bees track the scent of flowers to collect nectar, we developed cartilage-targeting hydrogel microspheres with reactive oxygen species (ROS)-responsive ability via combining the microfluidic method and photopolymerization processes to integrate cartilage-targeting peptides and ROS-responsive nanoparticles in the hydrogel matrix. The hydrogel microspheres with cartilage-targeting properties promoted better retention in the joint cavity and enhanced cellular uptake of the nanoparticles. Moreover, the ROS-responsive nanoparticles could react with osteoarthritis (OA)-induced intracellular ROS, resulting in the depolymerization of nanoparticles, which could not only eliminate excess ROS and reduce inflammation but also promote the release of dexamethasone (Dex) and kartogenin (KGN) in situ, realizing effective OA therapy. It was demonstrated that this hydrogel microsphere showed favorable ROS-responsive ability and enhanced chondrogenic differentiation as well as the downregulation of pro-inflammatory factors in vitro. Additionally, the hydrogel microspheres, similar to bees, could target and effectively repair cartilage in the OA model. Thus, the injectable hydrogel microspheres exerted an excellent potential to repair OA and may also provide an effective avenue for inflammatory bowel disease therapy.

Pentoxifylline/Valsartan co-delivery in liposomal gel alters the inflammatory HMGB-1/ TLR pathway and promotes faster healing in burn wounds: A promising repurposed approach

Burn wounds are one of the most severe complex forms of trauma. Hence, new treatment strategies that facilitate the healing process; reduce the severity and the healing time is the main concern of the health care systems. In this work, pentoxifylline-valsartan, (PTX- VAL), loaded liposomes integrated into gel were designed for the first time as a novel co-delivery carrier for the treatment of burn wounds. The objective of this work was to investigate the ability of the nano-based liposomal system to co-entrap two repurposed drugs; hydrophilic pentoxifylline and lipophilic valsartan for topical treatment of burn wounds. The impact of increasing the phospholipid amount to enhance the co-entrapment of PTX and VAL was investigated and in-vitro evaluation of the prepared formulations was conducted to choose the optimum composition with the highest entrapment of both drugs adopting a simple, reliable derivative spectrophotometric method. Structure elucidation was also performed using a transmission electron microscope. In addition, A simple selected derivative spectrophotometric method was developed for the assay of PTX-VAL novel combination. The proven selectivity, precision and accuracy assured the reliability of this analytical method. Being economic and fast makes routine application of the developed analytical method is recommended in pharmaceutical industry. The selected liposomal formulation integrated into gel matrix (PTX-VAL-LG) showed; nanometric size, acceptable entrapment efficiency of both PTX and VAL as well as sustained release profiles and thus, enhanced action.

Current Understanding of the Applications of Photocrosslinked Hydrogels in Biomedical Engineering

Hydrogel materials have great application value in biomedical engineering. Among them, photocrosslinked hydrogels have attracted much attention due to their variety and simple convenient preparation methods. Here, we provide a systematic review of the biomedical-engineering applications of photocrosslinked hydrogels. First, we introduce the types of photocrosslinked hydrogel monomers, and the methods for preparation of photocrosslinked hydrogels with different morphologies are summarized. Subsequently, various biomedical applications of photocrosslinked hydrogels are reviewed. Finally, some shortcomings and development directions for photocrosslinked hydrogels are considered and proposed. This paper is designed to give researchers in related fields a systematic understanding of photocrosslinked hydrogels and provide inspiration to seek new development directions for studies of photocrosslinked hydrogels or related materials.