KGRT peptide incorporated hydrogel with antibacterial activity for wound healing by optimizing cellular functions via ERK/eNOS signaling.

Bacterial infected wounds, which is characterized by easy infection, multiple inflammation and slow healing, is a complex symptom, resulting from metabolic disorder of the wound microenvironment. In this study, a series of self-healing double-network hydrogels based on KGRT peptide (Lys-Gly-Arg-Thr) with antibacterial, anti-inflammatory and optimizing cellular functions were designed to promote the healing of infected wounds with full-thickness skin defects. Moreover, the dextran hydrogelintroduces a large number of side chains, which are entangled with each other in the Schiff base network to form an interpenetrating structure. The hydrogel might regulate cell metabolism, differentiation and vascular endothelial growth factor (VEGF) function. Importantly, both in vitro and in vivo data showed that hydrogel not only has good antibacterial properties (99.8 %), but also can eradicate bacterial biofilm, effectively reduce inflammation (down-regulated IL-1ß, TNF-α and ROS) and accelerate chronic wound healing process by speeding-up wound closure, increasing granulation tissue thickness, collagen deposition, angiogenesis (up-regulated CD31). The hydrogel could up-regulate mRNA expression of PI3K, AKT, ERK, eNOS, HIF-1α and VEGF, which were correlated with wound healing. Consistently, the hydrogel could promote infected wounds healing and inhibit inflammation through ERK/eNOS signaling pathway. Collectively, hydrogel has excellent clinical application potential for promoting infected wound healing.

Simultaneous antioxidant and neuroprotective effects of two-dimensional (2D) MXene-loaded isoquercetin for ischemic stroke treatment.

Oxidative stress and reactive oxygen species drive ischemic stroke and its related complications. New antioxidant medications are therefore crucial for treating ischemic stroke. We developed Ti2C@BSA-ISO nanocomposites loaded with the hydrophobic drug isoquercetin (ISO) encapsulated in BSA on Ti2C nano-enzymes as a novel therapeutic nanomedicine for the treatment of ischemic stroke targeting reactive oxygen species (ROS). TEM visually proved the successful preparation of Ti2C@BSA-ISO, and the FTIR, XPS, zeta potential and DLS together demonstrated the acquisition of Ti2C@BSA-ISO. In addition, the enzyme-mimicking activity of Ti2C was evaluated and the antioxidant capacity of Ti2C@BSA-ISO was verified. Ti2C@BSA-ISO was able to reverse the decrease in cellular activity caused by ROS. Experiments in vivo showed that Ti2C@BSA-ISO could promote neuroprotection and scavenging of ROS in the hippocampal CA1 area and cerebral cortex of rats, thereby inhibiting cellular death and alleviating ischaemic stroke. Specifically, Ti2C@BSA-ISO alleviated ischemic stroke by inhibiting NLRP3/caspase-1/GSDMD pathway-mediated pyroptosis. Our study demonstrates the effectiveness of nanomedicines that can be directly used as drugs for the treatment of ischemic stroke in synergy with other drugs, which greatly expands the application of nanomaterials in the treatment of ischemic stroke.

Pathologically catalyzed physical coating restores the intestinal barrier for inflammatory bowel disease therapy.

Intestinal epithelia impairment of inflammatory bowel disease (IBD) leads to the leakage of bacteria and antigens and the consequent persistent immune imbalance. Restoring the epithelial barrier is a promising therapeutic target but lacks effective and safe clinical interventions. By identifying the catalase (CAT) presence in the IBD pathological environment, we herein develop a CAT-catalyzed pathologically coating on the damaged epithelial barrier to inhibit intestinal leakage for IBD therapy. With the codelivery of CaO2 (a CAT substrate) and dopamine, the nanosystem can enable CAT-catalyzed oxygen (O2) production and in-situ polymerization of dopamine and then yield a thin and integrative polydopamine (PDA) coating on the intestinal barrier due to the highly adhesive property of PDA. In vivo study demonstrates that PDA coating provides not only a protective barrier by restricting intestinal leakage but also a favorable anti-inflammation effect. Beyond drug management, this work provides a physical repair strategy via catalyzed coating for IBD therapy.

Antioxidant-Engineered Milk-Derived Extracellular Vesicles for Accelerating Wound Healing via Regulation of the PI3K-AKT Signaling Pathway.

Inspired by the experience of relieving inflammation in infants with milk, antioxidant-engineered milk-derived extracellular vesicles (MEVs) are developed to evaluate their potential for accelerating wound healing. In this work, MEVs with polydopamines (PDA) are engineered using the co-extrusion method. Subsequently, the authors incorporated them into a Schiff-based crosslink hydrogel, forming a skin dosage form that could facilitate the wound healing process. The antioxidant properties of PDA assist in the anti-inflammatory function of engineered MEVs, while the gel provides better skin residency. The PDA@MEVs+GEL formulation exhibits excellent biocompatibility, pro-angiogenic capacity, and antioxidant ability in vitro. Furthermore, in vivo experiments demonstrate its efficacy in wound repair and inflammation inhibition. Mechanistically, PDA@MEVs+GEL simultaneously promotes the growth, migration, and anti-inflammation of 3T3 cells by activating PI3K-AKT pathway. Moreover, PDA@MEVs+GEL exhibits enhanced functionality in promoting wound healing in vivo, attributed to its ability to inhibit inflammation, stimulate angiogenesis, and promote collagen synthesis. In conclusion, this study delves into the mechanism of MEVs and underscores the improved efficacy of engineered extracellular vesicles. Additionally, the feasibility and prospect of engineered MEVs in treating skin wounds are verified, suggesting that antioxidant-engineered MEVs could be a promising therapeutic agent for wound healing applications.

Native and engineered exosomes for inflammatory disease.

Exosomes are extracellular vesicles which carry specific molecular information from donor cells and act as an intercellular communication vehicle, which have emerged as a novel cell-free strategy for the treatment of many diseases including inflammatory disease. Recently, rising studies have developed exosome-based strategies for novel inflammation therapy due to their biocompatibility and bioactivity. Researchers not only use native exosomes as therapeutic agents for inflammation, but also strive to make up for the natural defects of exosomes through engineering methods to improve and update the property of exosomes for enhanced therapeutic effects. The engineered exosomes can improve cargo-loading efficiency, targeting ability, stability, etc., to achieve combined and diverse treatment strategies in inflammation diseases. Herein, a comprehensive overview of the recent advances in application studies of native and engineered exosomes as well as the engineered methods is provided. Meanwhile, potential application prospects, possible challenges, and the development of clinical researches of exosome treatment strategy are concluded from plentiful examples, which may be able to provide guidance and suggestions for the future research and application of exosomes.

Acidic and hypoxic tumor microenvironment regulation by CaO2-loaded polydopamine nanoparticles.

Hypoxia and high accumulation of lactic acid in the tumor microenvironment provide fertile soil for tumor development, maintenance and metastasis. Herein, we developed a calcium peroxide (CaO2)-loaded nanostructure that can play a role of "one stone kill two birds", i.e., acidic and hypoxic tumor microenvironment can be simultaneously regulated by CaO2 loaded nanostructure. Specifically, CaO2-loaded mesoporous polydopamine nanoparticles modified with sodium hyaluronate (denoted as CaO2@mPDA-SH) can gradually accumulate in a tumor site. CaO2 exposed in acidic microenvironment can succeed in consuming the lactic acid with oxygen generation simultaneously, which could remodel the acid and hypoxia tumor microenvironment. More importantly, the relief of hypoxia could further reduce lactate production from the source by down-regulating the hypoxia inducible factor-1α (HIF-1α), which further down-regulated the glycolysis associated enzymes including glycolysis-related glucose transporter 1 (GLUT1) and lactate dehydrogenase A (LDHA). As a result, CaO2@mPDA-SH alone without the employment of other therapeutics can dually regulate the tumor hypoxia and lactic acid metabolism, which efficiently represses tumor progression in promoting immune activation, antitumor metastasis, and anti-angiogenesis.

HACE2-Exosome-Based Nano-Bait for Concurrent SARS-CoV-2 Trapping and Antioxidant Therapy.

Corona Virus Disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is seriously threatening human health. Following SARS-CoV-2 infection, immune cell infiltration creates an inflammatory and oxidative microenvironment, which can cause pneumonia, severe acute respiratory syndrome, kidney failure, and even death. Clinically, a safe and effective treatment strategy remains to be established. Herein, a nano-bait strategy for inhibition of SARS-CoV-2 infection by redirecting viral attack while simultaneously relieving inflammation is developed. Specifically, the nano-bait was based on the exosome-sheathed polydopamine (PDA@Exosome) nanoparticles, which were generated by exocytosis of the PDA nanoparticles from H293T cells. In this approach, PDA@Exosome inherits from the source cells of H293T cells a surface display of ACE2 through pre-engineered expression. The resulting PDA@Exosome can compete with ACE2-expressing epithelial cells for S protein binding, in either the pre-exposure or post-exposure route. Moreover, relying on the ability of PDA to intercept and deactivate radical species, the PDA@Exosome can significantly attenuate the level of inflammatory cytokines by mediating oxidative stress, a major cause of organ injury. Due to its high trapping, multiple antioxidant ability, and good biocompatibility, the HACE2-exosome based nano-bait is a promising robust antiviral nanotherapeutics for the ongoing COVID-19 pandemic.

Antibiotics armed neutrophils as a potential therapy for brain fungal infection caused by chemotherapy-induced neutropenia.

Chemotherapy-induced neutropenia, a symptom of neutrophil depletion, makes cancer patients highly susceptible to invasive fungal infection with substantial morbidity and mortality. To address the cryptococcal brain infection in this condition, this study attempts to arm neutrophils (NEs) with antibiotics to potentiate the antifungal capability of NEs. To allow effective integration, amphotericin B, a potent antibiotic, is assembled with albumin nanoparticles through hydrophobic and hydrogen-bond interactions to form AmB@BSA nanoparticles (A-NPs). The nutrient composition (albumin) and virus-like size (~40 nm) facilitate efficient uptake of A-NPs by NEs to construct the antibiotics-armed NEs. It is demonstrated that the armed NEs can maintain the intrinsic biological functions of NEs, such as cell viability and capacity of migration to an inflammatory site. In a neutropenic mouse model of brain fungal infection, the treatment with the armed NEs allows for preventing fungal invasion more effectively than that with the native NEs, without the apparent systemic toxicity. Such a synergistic anti-infection system maximizes the antifungal effects by taking advantage of NEs and antibiotics. It provides a potential NEs-mediated therapeutic approach for treating fungal infection caused by chemotherapy-induced neutropenia.

A vaccine for photodynamic immunogenic cell death: tumor cell caged by cellular disulfide-thiol exchange for immunotherapy.

It has been suggested that immunogenic cell death (ICD) has therapeutic potential; however, its anticancer immunity is considerably hampered by the in situ immunosuppressive microenvironment within the tumor area, such as the dysfunction of antigen-presenting cells. Herein, we present an in vitro ICD-inducing modality to circumvent such impairment of immune activation. To this end, a "hot", i.e., immunogenic, whole tumor cell vaccine is generated in vitro and subcutaneously vaccinated in the normal tissue, departing from the site of the in situ immunosuppressive tumor area, to fully leverage the ICD-inducing antitumor immunity. In particular, the immunogenic dying tumor cells, caged by cellular disulfide-thiol exchange, are mediated by photoactivation. After subcutaneous vaccination, the photoactivated caged live cell vaccine (CLCV) exerts multi-durable immunostimulatory property, which, when adjuvanted by CpG, efficiently promotes dendritic cell (DC) activation and elicits robust CD8+ T-cell responses in vivo. Importantly, the generated T-cell responses are shown to protect 75% mice preimmunized with CLCV against tumor initiation and significantly retards tumor growth in the therapeutic setting. The strategy presented here may help to enrich the current vaccine design for cancer immunotherapy.

Nanoparticle reinforced bacterial outer-membrane vesicles effectively prevent fatal infection of carbapenem-resistant Klebsiella pneumoniae.

Infection resulting from carbapenem-resistant Klebsiella pneumoniae (CRKP) is an intractable clinical problem. Outer membrane vesicles (OMVs) from CRKP are believed to be potential vaccine candidates. However, their immune response remains elusive due to low structural stability and poor size homogeneity. In this study, hollow OMVs were reinforced internally by size-controlled BSA nanoparticles to obtain uniform and stable vaccines through hydrophobic interaction. The result showed that the BSA-OMV nanoparticles (BN-OMVs) were homogenous with a size around 100 nm and exhibited a core-shell structure. Remarkably, subcutaneous BN-OMVs vaccination mediated significantly higher CRKP specific antibody titers. The survival rate of the mice infected with a lethal dose of CRKP was increased significantly after BN-OMV immunization. The adoptive transfer experiment demonstrated that the protective effect of BN-OMVs was dependent on humoral and cellular immunity. This study demonstrated that the structure optimization improved the immune efficacy of OMVs for vaccine development against CRKP.

Self-Albumin Camouflage of Carrier Protein Prevents Nontarget Antibody Production for Enhanced LDL-C Immunotherapy.

Elevated low-density lipoprotein cholesterol (LDL-C) increases the risk of atherosclerotic cardiovascular disease. Peptide-based PCSK9 vaccines have shown a promising prospect of reducing LDL-C. In peptide vaccine (pVax) design, the peptide antigens need to conjugate with carrier protein (CP). However, CP incorporation can induce undesirable anti-CP antibodies, which sterically mask peptide epitopes from being recognized by specific B cells and impair subsequent therapeutically antibody production. This epitopic suppression has posed a barrier in clinical translation of conjugate vaccines all along. A model CP (keyhole limpet hemocyanin, KLH) is herein camouflaged with serum albumin (SA) into hybrid nanocarriers (SA@N), with PCSK9 peptide being anchored onto the surface to form nanovaccine (SA@NVax). Such camouflage of KLH via high "self" SA coverage is able to inhibit KLH from extracellular immune recognition and prevent detectable anti-KLH antibody production. Furthermore, the nanovaccine around 70 nm stabilized by intermolecular disulfide network is ideal for internalization and biodegradation by antigen presenting cells as well as better retention in draining lymph nodes and spleen. As expected, the SA@NVax efficiently primes higher anti-PCSK9 IgG antibody titer than PCSK9 pVax.

Facile and eco-friendly preparation of super-amphiphilic porous polycaprolactone.

Super-amphiphilic (highly oleophilic and hydrophilic) materials have attracted tremendous interest for fundamental research and potential applications, owing to their unique affinity for both oil and water. In this work, a novel super-amphiphilic porous polycaprolactone (PCL) was fabricated via an efficient and eco-friendly method, in which stearic acid (SA) was used as both a porogen and a dopant precursor. The porous PCL had an interconnected hierarchical pore structure and was capable of absorbing oil and water rapidly. The complementary cooperation of the oleophilic and hydrophilic domains on the pore surface induced the amphiphilicity, while the capillary forces caused a wicking action. The synergy of the two effects gave rise to the super-wetting property. The special amphiphilic feature of the porous PCL had a positive effect on its biocompatibility and the material can be considered as a promising candidate for tissue engineering applications.

Fever-Inspired Immunotherapy Based on Photothermal CpG Nanotherapeutics: The Critical Role of Mild Heat in Regulating Tumor Microenvironment.

Although there have been more than 100 clinical trials, CpG-based immunotherapy has been seriously hindered by complications in the immunosuppressive microenvironment of established tumors. Inspired by the decisive role of fever upon systemic immunity, a photothermal CpG nanotherapeutics (PCN) method with the capability to induce an immunofavorable tumor microenvironment by casting a fever-relevant heat (43 °C) in the tumor region is developed. High-throughput gene profile analysis identifies nine differentially expressed genes that are closely immune-related upon mild heat, accompanied by IL-6 upregulation, a pyrogenic cytokine usually found during fever. When treated with intratumor PCN injection enabling mild heating in the tumor region, the 4T1 tumor-bearing mice exhibit significantly improved antitumor immune effects compared with the control group. Superb efficacy is evident from pronounced apoptotic cell death, activated innate immune cells, enhanced tumor perfusion, and intensified innate and adaptive immune responses. This work highlights the crucial role of mild heat in modulating the microenvironment in optimum for improved immunotherapy, by converting the tumor into an in situ vaccine.

"Minimalist" Nanovaccine Constituted from Near Whole Antigen for Cancer Immunotherapy.

One of the major challenges in vaccine design has been the over dependence on incorporation of abundant adjuvants, which in fact is in violation of the "minimalist" principle. In the present study, a compact nanovaccine derived from a near whole antigen (up to 97 wt %) was developed. The nanovaccine structure was stabilized by free cysteines within each antigen (ovalbumin, OVA), which were tempospatially exposed and heat-driven to form an extensive intermolecular disulfide network. This process enables the engineering of a nanovaccine upon integration of the danger signal (CpG-SH) into the network during the synthetic process. The 50 nm-sized nanovaccine was developed comprising approximately 500 antigen molecules per nanoparticle. The nanovaccine prophylactically protected 70% of mice from tumorigenesis (0% for the control group) in murine B16-OVA melanoma. Significant tumor inhibition was achieved by strongly nanovaccine-induced cytotoxic T lymphocytes. This strategy can be adapted for the future design of vaccine for a minimalist composition in clinical settings.

Synthesis of well-defined star, star-block, and miktoarm star biodegradable polymers based on PLLA and PCL by one-pot azide-alkyne click reaction.

Based on the "arm-first" strategy, ring-opening polymerization (ROP) and one-pot azide-alkyne click reaction, well-defined star-shaped polymers with different architectures have been successfully synthesized, including the star homopolymers four-arm star-shaped polycaprolactone (4sPCL) and four-arm star-shaped poly(l-lactic acid) (4sPLLA), star-block copolymer 4sPCL-b-PLLA and miktoarm star-shaped copolymer PCL2PLLA2. The star homopolymers 4sPCL and 4sPLLA were synthesized by a click reaction of an azide small molecule initiator and HC[triple bond, length as m-dash]C-PCL or HC[triple bond, length as m-dash]C-PLLA. The star-block copolymer 4sPCL-b-PLLA was synthesized by a click reaction of an azide small molecule initiator and the block copolymer HC[triple bond, length as m-dash]C-PCL-b-PLLA. The miktoarm star polymer PCL2PLLA2 was synthesized by a one-pot azide-alkyne click reaction of simultaneous addition of equal proportions of HC[triple bond, length as m-dash]C-PCL and HC[triple bond, length as m-dash]C-PLLA. The structures of these star-shaped polymers have been confirmed by NMR, FT-IR and GPC. Furthermore, the melting and crystallization behaviors investigated using DSC and WXRD also confirm the formation of star-shaped polymers with different architectures.

Facile preparation of degradable multi-arm-star-branched waterborne polyurethane with bio-based tannic acid.

In this research, biodegradable multi-arm-star-branched waterborne polyurethanes (MWPUs) were prepared by incorporation of bio-based material (tannic acid, TA) in the structure of waterborne polyurethanes. The prepared MWPUs were characterized by UV-vis spectrometry and FT-IR spectrometry, confirming the presence of TA in MWPUs. The results of DSC and TGA demonstrated that the incorporation of TA remarkably enhanced the thermal stability of MWPUs. The mechanical strength test indicated that the Young's modulus and tensile strength of the waterborne polyurethanes after incorporation of TA were significantly improved due to the increase of structural rigidity, hydrogen bonding and the molecular interactions of the TA-based MWPU chains. In addition, the synthesized TA-based MWPUs also exhibited excellent antioxidation capacity and outstanding biodegradation property. Given these excellent properties and the sustainability of TA, the developed TA-based MWPUs exhibited great potential in a wide range of practical applications.

In situ and controllable synthesis of Ag NPs in tannic acid-based hyperbranched waterborne polyurethanes to prepare antibacterial polyurethanes/Ag NPs composites.

In this research, a simple and facile method was developed for preparation of antibacterial polyurethanes/Ag NPs composites, where tannic acid-based hyperbranched waterborne polyurethanes (THWPU) was employed as both reductant and stabilizer to in situ and controllably synthesize Ag NPs at mild room temperature. The resultant Ag NPs in THWPU was confirmed by UV spectrophotometer, SEM and EDX. The effects of reaction temperature on the properties of the formed Ag NPs were investigated, and the results showed that the formed Ag NPs under room temperature and 80 °C were both spherical, whereas increasing the reaction temperature benefits for promoting the formation of Ag NPs and narrowing the size distribution of the formed Ag NPs. Furthermore, triangular Ag NPs were in situ synthesized in THWPU via adding strong reductant (NaBH4) during the formation of Ag NPs. Both spherical and triangular Ag NPs enhanced the mechanical property, thermal stability and antibacterial performance of THWPU. More importantly, our results demonstrated that formation of spherical Ag NPs in THWPU were beneficial for improving the mechanical property and thermal stability of THWPU, while the formation of triangular Ag NPs enabled THWPU better antibacterial performance against E. coli and S. aureus. Given these advantages, our obtained Ag NPs nanocomposites could be suitable for a broad range of commercial applications, such as medical products, children's products.

Disulfide-Bridged Cleavable PEGylation of Poly-L-Lysine for SiRNA Delivery.

Engineered PEG-cleavable catiomers based on poly-L-lysine have been developed as nonviral gene vectors, which have been found to be one of important methods to balance "PEG dilemma." In this protocol, we aim at the standardization of the method and procedure of PEG-cleavable catiomers. Major steps including ring-opening polymerization (ROP) of ε-benzyloxycarbonyl-L-lysine N-carboxyanhydride (zLL-NCA) monomers to yield PEG-cleavable polylysine, examination on bio-stability and bio-efficacy of its gene complexes are described.

Harnessing the PEG-cleavable strategy to balance cytotoxicity, intracellular release and the therapeutic effect of dendrigraft poly-l-lysine for cancer gene therapy.

Dendrimer catiomers like dendrigraft poly-l-lysine (DGL) have been very popular vectors for gene delivery recently; however, they generally suffer from serious cytotoxicity for high density of positive charge. PEGylated DGL engineered using the PEG cleavable mechanism (DGL(R)-SS-mPEG) was first developed as a non-viral gene vector for cancer intervention. Cleavable PEGylation of the DGL catiomer in tumor relevant glutathione (GSH) conditions enables us to dramatically decrease the cytotoxicity as well as to promote the intracellular release and expression of the genetic payload. Like DGL, DGL(R)-SS-mPEG is capable of efficiently complexing with plasmid DNA (pDNA) to afford homogeneous compact nano-complexes. Those gene carrying nanostructures could be stably dispersed in the regular serum medium without GSH, but with fast PEG dis-assembly if subject to 10 mM GSH. Compared with the non-cleavable counterpart, PEG-cleavable dendrigraft poly-l-lysine exhibited significantly higher enhanced green fluorescence protein (EGFP) expression against 293T cells. By using small interfering RNA (siRNA-VEGF) as the therapeutic gene payload, the complex nanoparticles demonstrated the pronounced inhibition effect on cell growth in vitro and tumor growth in vivo. The promising results revealed a universal strategy to balance disadvantages and advantages of dendrimer catiomers for future non-viral gene delivery vector.