3D printing of implantable elastic PLCL copolymer scaffolds.

Poly(l-lactic acid) (PLLA) scaffolds have been used in regenerative medicine, however, they commonly suffer from low flexibility, restricting their application in the repair and reconstruction of soft tissues. In this study, poly(l-lactide-co-ε-caprolactone) (PLCL) copolymers were examined to modulate the elasticity of PLLA with the random presence of CL units in PLLA. Thermodynamic analysis revealed that the introduction of PCL could significantly decrease the melting point and glass transition temperature of PLLA, benefiting the extrusion and printing of PLCL. Diverse scaffolds with designed architectures including porous cubes with or without large holes, cambered plates with holes and round tubes could be easily constructed by 3D printing. In the process of elastic deformation, the maximum elastic stress of the copolymer scaffold was obviously increased from 19.6 to 31.5 MPa when the relative content of PCL was increased to 70%, while the elongation at break was evidently increased from 388% to about 1974%. The Young's modulus of PLCL was also significantly decreased (P < 0.05) in comparison with that of PLLA. PLCL scaffolds have good platelet and endotheliocyte adhesion ability and no obvious hemolysis was observed. In vivo subcutaneous implantation of PLCL scaffolds demonstrated superior biocompatibility. Collectively, this work highlights that copolymerization of PCL segments into PLLA is an effective approach to tune the 3D printability and the stiffness and elasticity of PLLA scaffolds. PLCL scaffolds hold great promise for the regeneration of soft tissues including but not limited to cartilage, myocardium, muscle, tendon and nervous tissues.

An injectable thermosensitive hydrogel self-supported by nanoparticles of PEGylated amino-modified PCL for enhanced local tumor chemotherapy.

We synthesized amino-modified poly(ε-caprolactone) PCN-b-PEG-b-PCN (PECN) triblock copolymers and studied the contribution of the introduced amino groups to the drug delivery efficiency of PECN nanoparticles (NPs) and their injectable thermosensitive hydrogels. PECN15 with an optimal amino group content was obtained. Firstly, the hydrophobic drug paclitaxel (PTX) was loaded into PECN15 up to 5.91% and formed PTX/PECN NPs 90 nm in size and with a slightly positive charge (7.3 mV). Furthermore, the injectable PTX/PECN NPs aqueous solution (25 wt%) at ambient temperature could undergo fast gelation at 37 °C and sustainedly release PTX/PECN NPs in 10 days. More importantly, compared with our previously reported PECT NPs, the PECN NPs without an increase in toxicity could improve the cell uptake and enhance intracellular drug release by responding to the acidic environment of the endosome. Thus, the PTX/PECN NPs presented a lower IC50 of 3.14 µg mL-1 than that of the PTX/PECT NPs (7.67 µg mL-1) and free PTX (4.65 µg mL-1). Moreover, through peritumoral injection, the PTX/PECNGel showed 94.27% inhibition rate of tumor growth on day 19, higher than PTX/PECTGel (72.28%) and Taxol® (47.03%). Therefore, the PECN NPs hydrogel provided a more effective injectable platform to enhance local cancer chemotherapy, and also provided the possibility of further functionalization by the reactive amino groups.

Engineering Dendritic-Cell-Based Vaccines and PD-1 Blockade in Self-Assembled Peptide Nanofibrous Hydrogel to Amplify Antitumor T-Cell Immunity.

Dendritic cells (DCs) are increasingly used in cancer vaccines due to their ability to regulate T-cell immunity. Major limitations associated with the present DC adoptive transfer immunotherapy are low cell viability and transient duration of transplanted DCs at the vaccination site and the lack of recruitment of host DCs, leading to unsatisfactory T-cell immune response. Here, we developed a novel vaccine nodule comprising a simple physical mixture of the peptide nanofibrous hydrogel, anti-PD-1 antibodies, DCs, and tumor antigens. Upon subcutaneous injection, the vaccine nodule maintained the viability and biological function including the antigen uptake and maturation of encapsulated DCs and simultaneously recruited a number of host DCs and promoted the drainage of activated DCs to lymph nodes, resulting in enhanced proliferation of antigen-specific splenocytes and provoking potent cellular immune responses. Compared with adoptive transfer of DCs and subcutaneous administration of antigen vaccine, such a vaccine nodule shows superior antitumor immunotherapy efficiency in both prophylactic and therapeutic tumor models including delayed tumor growth and prolonged mice survival due to effective stimulation of antitumor T-cell immunity and increased infiltration of activated CD8+ effector T-cells in the tumor. Our findings provide a simple and robust vaccination strategy for DC-based vaccines and also a unique vaccine product for stimulating and enhancing T-cell immunity, holding great promise for immunotherapy against cancer and infectious diseases.

A Light Responsive Nanoparticle-Based Delivery System Using Pheophorbide A Graft Polyethylenimine for Dendritic Cell-Based Cancer Immunotherapy.

In this study, the photochemical internalization (PCI) technique was adopted in a nanoparticle-based antigen delivery system to enhance antigen-specific CD8+ T cell immune response for cancer immunotherapy. Pheophorbide A, a hydrophobic photosensitizer, grafted with polyethylenimine (PheoA-PEI) with endosome escape activity and near-infrared imaging capability was prepared. A model antigen ovalbumin (OVA) was then complexed with PheoA-PEI to form PheoA-PEI/OVA nanoparticles (PheoA-PEI/OVA NPs) that are responsive to light. Flow cytometry analysis revealed increased endocytosis in a murine dendritic cell line (DC2.4) that was treated with PheoA-PEI/OVA NPs compared to free OVA. Generation of reactive oxygen species (ROS) in DC2.4 cells was also confirmed quantitatively and qualitatively using 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA). Confocal laser scanning microscopy (CLSM) further demonstrated that the PheoA-PEI/OVA NPs enhanced cytosolic antigen release after light stimulation. Moreover, PheoA-PEI/OVA NP treated DC2.4 cells exhibited enhanced cross-presentation to B3Z T cell hybridoma in vitro after light irradiation, substantially increased compared to those treated with free OVA. Consistently, in vivo results revealed upregulation of CD3+CD8+T lymphocytes in tumors of mice treated with dendritic cells plus PheoA-PEI/OVA NPs and light irradiation. The activated T cell response is partly responsible for the inhibitory effect on E.G7 tumor growth in mice immunized with dendritic cells plus PheoA-PEI/OVA NPs and light irradiation. Our results demonstrate the feasibility to enhance antigen-specific CD8+ T cell immune response by light-responsive nanoparticle-based vaccine delivery for cancer immunotherapy.

Integrin-targeted zwitterionic polymeric nanoparticles with acid-induced disassembly property for enhanced drug accumulation and release in tumor.

Reasonably structural design of nanoparticles (NPs) to combine functions of prolonged systemic circulation, enhanced tumor targeting and specific intracellular drug release is crucial for antitumor drug delivery. Combining advantages of Arg-Gly-Asp (RGD) for active tumor targeting, zwitterionic polycarboxybetaine methacrylate (PCB) for prolonged systemic circulation, poly(2-(diisopropylamino) ethyl methacrylate) (PDPA) for acid-triggered intracellular release, novel RGD-PCB-b-PDPA (RGD-PCD) block copolymers were prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization and followed by functionalization with RGD. Doxorubicine (DOX) was encapsulated within the RGD-PCD NPs as model medicine (RGD-PCD/DOX NPs). With ultra pH-sensitivity of PDPA, the drug release was restrained at pH 7.4 for only 24% within 36 h, which was increased to 60% at pH 6.0 within 24 h, and released more rapidly at pH 5.0 for 100% within 5 h, indicating that the RGD-PCD/DOX NPs were able to turn drug release "off" at neutral pH (e.g., systemic circulation) whereas "on" under acidic conditions (e.g., inside endo/lysosomes). Furthermore, the results of fluorescence microscopy and flow cytometry analysis demonstrated improved internalization of RGD-PCD/DOX NPs in HepG2 cells via integrin-mediated endocytosis with rapid DOX release intracellularly. Consequently, the RGD-PCD/DOX NPs showed considerable cytotoxicity against HepG2 and HeLa cells in comparison with free DOX. Importantly, the RGD-PCD/DOX NPs exhibited little protein adsorption property with excellent serum stability, which led to prolonged systemic circulation and enhanced tumor accumulation in tumor-bearing nude mice. Therefore, this multifunctional RGD-PCD NPs, which represented the flexible design approach, showed great potential for the development of novel nanocarriers in tumor-targeted drug delivery.

Bioactive microgel-coated electrospun membrane with cell-instructive interfaces and topology for abdominal wall defect repair.

Current mesh materials used for the clinical treatment of abdominal defects struggle to balance mechanical properties and bioactivity to support tissue remodeling. Therefore, a bioactive microgel-coated electrospinning membrane was designed with the superiority of cell-instructive topology in guiding cell behavior and function for abdominal wall defect reconstruction. The electrostatic spinning technique was employed to prepare a bioabsorbable PLCL fiber membrane with an effective mechanical support. Additionally, decellularized matrix (dECM)-derived bioactive microgels were further coated on the fiber membrane through co-precipitation with dopamine, which was expected to endow cell-instructive hydrophilic interfaces and topological morphologies for cell adhesion. Moreover, the introduction of the dECM into the microgel promoted the myogenic proliferation and differentiation of C2C12 cells. Subsequently, in vivo experiments using a rat abdominal wall defect model demonstrated that the bioactive microgel coating significantly contributed to the reconstruction of intact abdominal wall structures, highlighting its potential for clinical application in promoting the repair of soft tissue defects associated with abdominal wall damage. This study presented an effective mesh material for facilitating the reconstruction of abdominal wall defects and contributed novel design concepts for the surface modification of scaffolds with cell-instructive interfaces and topology.

Biodegradable Cardiac Occluder with Surface Modification by Gelatin-Peptide Conjugate to Promote Endogenous Tissue Regeneration.

Transcatheter intervention has been the preferred treatment for congenital structural heart diseases by implanting occluders into the heart defect site through minimally invasive access. Biodegradable polymers provide a promising alternative for cardiovascular implants by conferring therapeutic function and eliminating long-term complications, but inducing in situ cardiac tissue regeneration remains a substantial clinical challenge. PGAG (polydioxanone/poly (l-lactic acid)-gelatin-A5G81) occluders are prepared by covalently conjugating biomolecules composed of gelatin and layer adhesive protein-derived peptides (A5G81) to the surface of polydioxanone and poly (l-lactic acid) fibers. The polymer microfiber-biomacromolecule-peptide frame with biophysical and biochemical cues could orchestrate the biomaterial-host cell interactions, by recruiting endogenous endothelial cells, promoting their adhesion and proliferation, and polarizing immune cells into anti-inflammatory phenotypes and augmenting the release of reparative cytokines. In a porcine atrial septal defect (ASD) model, PGAG occluders promote in situ tissue regeneration by accelerating surface endothelialization and regulating immune response, which mitigate inflammation and fibrosis formation, and facilitate the fusion of occluder with surrounding heart tissue. Collectively, this work highlights the modulation of cell-biomaterial interactions for tissue regeneration in cardiac defect models, ensuring endothelialization and extracellular matrix remodeling on polymeric scaffolds. Bioinspired cell-material interface offers a highly efficient and generalized approach for constructing bioactive coatings on medical devices.

Nanogels co-loading paclitaxel and curcumin prepared in situ through photopolymerization at 532 nm for synergistically suppressing breast tumors.

Combined chemotherapy plays an increasingly important and practical role in the clinical treatment of malignant tumor. In this study, paclitaxel (PTX) and curcumin (Cur) are simultaneously encapsulated into nanogels (termed as NG-PC) in situ by microemulsion photopolymerization at 532 nm for synergistically suppressing breast tumors. NG-PC with a size of 180 nm and a low polydispersity index (PDI < 0.2) presents a controlled and cumulative release of PTX and Cur within 90 h. Moreover, NG-PC displays a remarkable killing effect against 4T1 and MCF-7 cells. In vivo antitumor evaluation on 4T1 tumor-bearing mice demonstrates that NG-PC has significantly higher ability to inhibit tumor growth, inducing necrosis, apoptosis and suppression of proliferation than that of a single drug. Our research provides a facile method to prepare a nano-drug delivery platform with excellent drug co-loading ability and synergistic antitumor effect.

ROS scavenging and immunoregulative EGCG@Cerium complex loaded in antibacterial polyethylene glycol-chitosan hydrogel dressing for skin wound healing.

The elevation of oxidative stress and inflammatory response after injury remains a substantial challenge that can deteriorate the wound microenvironment and compromise the success of wound healing. Herein, the assembly of naturally derived epigallocatechin-3-gallate (EGCG) and Cerium microscale complex (EGCG@Ce) was prepared as reactive oxygen species (ROS) scavenger, which was further loaded in antibacterial hydrogels as wound dressing. EGCG@Ce shows superior antioxidation capacity towards various ROS including free radical, O2- and H2O2 through superoxide dismutase-like or catalase-mimicking catalytic activity. Importantly, EGCG@Ce could provide mitochondrial protective effect against oxidative stress damages, reverse the polarization of M1 macrophages and reduce the secretion of pro-inflammatory cytokines. Furtherly, EGCG@Ce was loaded into the PEG-chitosan hydrogel with dynamic, porous, injectable and antibacterial properties as wound dressing, which accelerated the regeneration of both epidermal layer and dermis, resulting in improved healing process of full-thickness skin wounds in vivo. Mechanistically, EGCG@Ce re-shaped the detrimental tissue microenvironment and augmented the pro-reparative response through reducing ROS accumulation, alleviating inflammatory response, enhancing the M2 macrophage polarization and angiogenesis. Collectively, antioxidative and immunomodulatory metal-organic complex-loaded hydrogel is a promising multifunctional dressing for the repair and regeneration of cutaneous wounds without additional drugs, exogenous cytokines, or cells. STATEMENT OF SIGNIFICANCE: (1) We reported an effective antioxidant through self-assembly coordination of EGCG and Cerium for managing the inflammatory microenvironment at the wound site, which not only showed high catalytic capacity towards multiple ROS, but also could provide mitochondrial protective effect against oxidative stress damage, reverse the polarization of M1 macrophages and downregulate pro-inflammatory cytokines. EGCG@Ce was further loaded into porous and bactericidal PEG-chitosan (PEG-CS) hydrogel as a versatile wound dressing, which accelerated wound healing and angiogenesis. (2) The applicability of alleviating sustainable inflammation and regulating macrophage polarization through ROS scavenging is a promising strategy for tissue repair and regeneration without additional drugs, cytokines, or cells.

An anti-inflammatory chondroitin sulfate-poly(lactic-co-glycolic acid) composite electrospinning membrane for postoperative abdominal adhesion prevention.

Postoperative abdominal adhesion is a very common and serious complication, resulting in pain, intestinal obstruction and heavy economic burden. Post-injury inflammation that could activate the coagulation cascade and deposition of fibrin is a major cause of adhesion. Many physical barrier membranes are used to prevent abdominal adhesion, but their efficiency is limited due to the lack of anti-inflammatory activity. Here, an electrospinning membrane composed of poly(lactic-co-glycolic acid) (PLGA) providing support and mechanical strength and chondroitin sulfate (CS) conferring anti-inflammation activity is fabricated for preventing abdominal adhesion after injury. The PLGA/CS membrane shows a highly dense fiber network structure with improved hydrophilicity and good cytocompatibility. Importantly, the PLGA/CS membrane with a mass ratio of CS at 20% provides superior anti-adhesion efficiency over a native PLGA membrane and commercial poly(D, L-lactide) (PDLLA) film in abdominal adhesion trauma rat models. The mechanism is that the PLGA/CS membrane could alleviate the local inflammatory response as indicated by the promoted percentage of anti-inflammatory M2-type macrophages and decreased expression of pro-inflammatory factors, such as IL-1ß, TNF-α and IL-6, resulting in the suppression of the coagulation system and the activation of the fibrinolytic system. Furthermore, the deposition of fibrin at the abdominal wall was inhibited, and the damaged abdominal tissue was repaired with the treatment of the PLGA/CS membrane. Collectively, the PLGA/CS electrospinning membrane is a promising drug-/cytokine-free anti-inflammatory barrier for post-surgery abdominal adhesion prevention and a bioactive composite for tissue regeneration.

Supramolecular Polymer-Nanomedicine Hydrogel Loaded with Tumor Associated Macrophage-Reprogramming polyTLR7/8a Nanoregulator for Enhanced Anti-Angiogenesis Therapy of Orthotopic Hepatocellular Carcinoma.

Anti-angiogenic therapies targeting inhibition of vascular endothelial growth factor (VEGF) pathway show clinical benefit in hypervascular hepatocellular carcinoma (HCC) tumors. However, HCC expresses massive pro-angiogenic factors in the tumor microenvironment (TME) in response to anti-angiogenic therapy, recruiting tumor-associated macrophages (TAMs), leading to revascularization and tumor progression. To regulate cell types in TME and promote the therapeutic efficiency of anti-angiogenic therapy, a supramolecular hydrogel drug delivery system (PLDX-PMI) co-assembled by anti-angiogenic nanomedicines (PCN-Len nanoparticles (NPs)) and oxidized dextran (DX), and loaded with TAMs-reprogramming polyTLR7/8a nanoregulators (p(Man-IMDQ) NRs) is developed for orthotopic liver cancer therapy. PCN-Len NPs target tyrosine kinases of vascular endothelial cells and blocked VEGFR signaling pathway. p(Man-IMDQ) NRs repolarize pro-angiogenic M2-type TAMs into anti-angiogenic M1-type TAMs via mannose-binding receptors, reducing the secretion of VEGF, which further compromised the migration and proliferation of vascular endothelial cells. On highly malignant orthotopic liver cancer Hepa1-6 model, it is found that a single administration of the hydrogel formulation significantly decreases tumor microvessel density, promotes tumor vascular network maturation, and reduces M2-subtype TAMs, thereby effectively inhibiting tumor progression. Collectively, findings in this work highlight the great significance of TAMs reprogramming in enhancing anti-angiogenesis treatment for orthotopic HCC, and provides an advanced hydrogel delivery system-based synergistic approach for tumor therapy.

Nanogels loading curcumin in situ through microemulsion photopolymerization for enhancement of antitumor effects.

Drug-loaded nanogels for cancer treatment can limit the free diffusion and distribution of drug molecules in the whole body to reduce undesirable side effects and improve the drug absorption efficiency of the tumor. In this study, curcumin as a model drug was encapsulated into nanogels in situ through microemulsion photopolymerization at 532 nm. Nanogels loaded with curcumin (NG-C) displayed a diameter of around 150 nm with good stability and a low polydispersity index of around 0.1. NG-C had a drug-loading capacity of 8.96 ± 1.16 wt%. The cumulative release of curcumin from NG-C was around 25%, 34% and 55% within 90 h in pH 7.4, 6.8 and 5.0 PBS buffer, respectively. NG-C presented prominent cytotoxicity toward Hep G2 and HeLa cancer cells in vitro. Moreover, NG-C exhibited much a stronger inhibition of tumor growth, necrosis, apoptosis, and the suppression of proliferation compared with curcumin on Hep G2 tumor-bearing nude mice.

Skin-Adaptable, Long-Lasting Moisture, and Temperature-Tolerant Hydrogel Dressings for Accelerating Burn Wound Healing without Secondary Damage.

Developing multifunctional wound dressings, possessing not only skin-like mechanical properties and adaptability, long-lasting moisture, and temperature tolerance that maximally mimics the human skin but also on-demand adhesion without unnecessary bleeding and secondary damage upon peeling, is necessary but remains a challenge. Herein, a novel dual cross-linked and multifunctional hydrogel, termed PSNC hydrogel for polymerized sulfobetaine methacrylate (SBMA), N-(2-amino-2-oxyethyl)acrylamide (NAGA), and 1-carboxy-N-methyl-N-di(2-methacryloyloxy-ethyl)methanaminium inner salt (CBMAX), was fabricated as a wound dressing for burn injuries via one-pot radical polymerization in glycerine (GLY)/H2O solvent. The dual cross-linked network of the PSNC hydrogel combined the double hydrogen bonding of N-(2-amino-2-oxyethyl)acrylamide (NAGA) with a covalently cross-linked zwitterionic network, endowing the hydrogel with skin-like mechanical properties with a high stretchability of 1613.8 ± 79.8%, a tensile strength of 77.5 ± 1.8 kPa, and a tensile modulus of 1.9 ± 0.1 kPa. Moreover, the hydrogel with well-developed adaptability can withstand skin deformation without breaking or debonding attributed to its good tissue adhesiveness and self-healing ability. Further, the utilization of the GLY/H2O binary solvent effectively prevented the crystallization and evaporation of free water, endowing the hydrogel with not only long-lasting moisture but also excellent temperature tolerance in a wide range from -20 to 60 °C. More importantly, the PSNC hydrogel could effectively accelerate wound healing of burn injuries and could be easily removed on-demand with saline without causing secondary damage due to intense hydration. Such a novel PSNC zwitterionic hydrogel could be a promising candidate for the treatment of burn wounds and tissue regeneration.

Co-delivery of anionic epitope/CpG vaccine and IDO inhibitor by self-assembled cationic liposomes for combination melanoma immunotherapy.

Immunotherapy is revolutionizing cancer treatment. Vaccination of antigenic peptides has been identified as a promising strategy for cancer immunotherapy while insufficient immune responses were stimulated due to low antigenicity. Moreover, immune checkpoint blockade therapy is still limited by a low objective response rate. In this work, cationic polymer-lipid hybrid nanovesicle (P/LNV)-based liposomes are designed to simultaneously deliver tumor vaccines composed of anionic antigen epitopes, toll-like receptor-9 agonist (TLR9), CpG (AE/CpG), and indoleamine-2,3-dioxygenase (IDO) inhibitor, 1-methyl-tryptophan (1-MT), to increase the immunogenicity of peptide antigens and meanwhile block the immune checkpoint. P/LNV liposomes efficiently enhanced the uptake of vaccines by dendritic cells (DCs) and improved the maturation of DCs indicated by the significantly increased percentage of CD86+MHCI+ DCs, resulting in a potent cytotoxic T-lymphocyte (CTL) response against B16-OVA tumor cells in vitro. Importantly, the combination immunotherapy showed significantly higher therapeutic efficiency towards melanoma tumors in mice, compared with an untreated or individual therapy modality. Mechanistically, the co-delivery system could elicit a strong cancer-specific T-cell response, as characterized by the remarkably increased infiltration of CD8+ T cells in the tumor and draining lymph nodes. Altogether, cationic liposomes delivered with tumor vaccines and IDO inhibitor provide a promising platform for cancer immunotherapy by provoking antitumor T-cell immunity and simultaneously reversing the immunosuppressive tumor microenvironment.

pH-Sensitive Polycations for siRNA Delivery: Effect of Asymmetric Structures of Tertiary Amine Groups.

pH-sensitive polyelectrolytes provide enormous opportunity for siRNA delivery. Especially, their tertiary amine structures can not only bind genes but also act as pH-sensitive hydrophobic structure to control genes release. However, the influence of molecular structures on siRNA delivery still remains elusive, especially for the asymmetric alkyl substituents of the tertiary amine groups. Herein, a library of N-methyl-N-alkyl aminoethyl methacrylate monomers (MsAM) with asymmetric alkyl substituents on the tertiary amine group is synthesized and used to prepare a series of tri-block polycationic copolymers poly(aminoethyl methacrylate)-block-poly (N-methyl-N-alkyl aminoethyl methacrylate)-block-poly(ethylene glycol methacrylate) (PAMA-PMsMA-PEG). And the properties of these polycations and their self-assembled micelles are characterized, including molecular structure, proton buffering capacity, pH-sensitivity, size, and zeta potential. With the length increase of one alkyl substituent, the proton buffering capacity of both monomers and polycations is demonstrated to be narrowed down. The siRNA delivery efficiency and cytotoxicity of these micelles are also evaluated on HepG2 cells. In particular, poly(aminoethyl methacrylate)-block-poly(N-methyl-N-ethyl aminoethyl methacrylate)-block-poly(ethylene glycol methacrylate) (PAMA-PMEMA-PEG) elicited the best luciferase knockdown efficiency and low cytotoxicity. Besides, PAMA-PMEMA-PEG/siRRM2 also induced significant anti-tumor activity in vitro. These results indicated PAMA-PMEMA-PEG has potential for further use in the design of gene vehicles with the improved efficiency of siRNA delivery.

Combating drug-resistant bacterial infection using biodegradable nanoparticles assembled from comb-like polycarbonates grafted with amphiphilic polyquaternium.

Bacterial infection is a serious clinical threat. The misuse of antibiotics has already resulted in the emergence of antibiotic-resistant strains of pathogenic bacteria. Efficient membrane-destructive antibacterial agents are considered as an alternative, promising solution against bacterial infection. Herein, we prepared a new type of comb-like cationic, polyethylene glycol (PEG) block polycarbonates with polyquaternium arms (G-CgQAs). The amphiphilic G-CgQAs could self-assemble into about 60 nm sized nanoparticles (NPs) with positive charges (20~30 mV). G-CgQA-3 NPs with an appropriate hydrophobic-hydrophilic balance in the polyquaternium arms showed antibacterial activity against Gram-negative, Gram-positive, and drug-resistant strains at low concentrations (MIC 64-128 µg mL-1) and low hemolysis (HC50 > 2000 µg mL-1). In vivo anti-infection tests indicated G-CgQA-3 NPs could highly inhibit the growth of vancomycin-resistant bacteria by spraying on wounds. Collectively, G-CgQA NPs hold great promise for the prevention of infection, serving as new antibacterial agents. This study also highlights the significance of a hydrophobic block in positive polyquaternium arms to facilitate the antibacterial activity of cationic, quaternized polymers. The design of comb-like amphiphilic cationic polycarbonates provides a new method for manufacturing antibacterial nano-agents.

Polymer-lipid hybrid nanovesicle-enabled combination of immunogenic chemotherapy and RNAi-mediated PD-L1 knockdown elicits antitumor immunity against melanoma.

Immunotherapy has revolutionized cancer treatment; however, only a limited portion of patients show responses to currently available immunotherapy regimens. Here, we demonstrate that RNA interference (RNAi) combined with immunogenic chemotherapy can elicit potent antitumor immunity against melanoma. Specially, we developed cationic polymer-lipid hybrid nanovesicles (P/LNVs) as a new delivery system for doxorubicin and small interfering RNA (siRNA) with extensive cytotoxicity and gene silencing efficiency towards B16 cells. The deployment of doxorubicin-loaded P/LNVs augmented the expression and presentation of endogenous tumor antigens directly in situ by inducing the immunogenic cell death of B16 cells through poly(ADP-ribose) polymerase 1-dependent (PARP1) apoptosis pathway; thereby, eliciting remarkable antitumor immune responses in mice. Leveraging dying B16 cells as a vaccination strategy in combination with RNAi-based programmed cell death ligand 1 (PD-L1) knockdown showed efficacy in both prophylactic and metastasis melanoma settings. Strikingly, PD-L1 blockade synergized with a sub-therapeutic dose of doxorubicin triggered robust therapeutic antitumor T-cell responses and eradicated pre-established tumors in 30% of mice bearing B16 melanoma. Our findings indicated that this combination treatment provided a new powerful immunotherapy modality, characterized by markedly increased infiltration of effector CD8+ T cells and effective alleviation of the immunosuppressive microenvironment in tumors. P/LNVs is a versatile and highly scalable carrier that can enable a broad combination of nanomedicine and RNAi, providing new therapeutic strategies for advanced cancers.

Polymer Composite Sponges with Inherent Antibacterial, Hemostatic, Inflammation-Modulating and Proregenerative Performances for Methicillin-Resistant Staphylococcus aureus-Infected Wound Healing.

Clinical wound management remains a major challenge due to massive bleeding, bacterial infection, and difficult wound healing after tissue trauma. To simultaneously address these issues, composite polymer sponges for accelerating drug-resistant bacterial infected wound healing are fabricated by facilely mixing sodium polyacrylate (PAAS), double quaternary ammonium salts-conjugated chitosan (QAS-CS), and collagen (COL) in aqueous solution, followed by lyophilization. Composite sponges (PAAS/QAS-CS/COL, PQC) show highly porous microstructures (porosity ≈90%) with moderate compress modulus (≈0.3 MPa), tensile strength (0.004 MPa), and high swelling ratio (≈3500%). Importantly, PQC sponge demonstrates superior hemostasis ability over commercially available CS sponge by inducing rapid hemagglutination, and exhibits significantly better antibacterial activity against both methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli by destroying cell membrane and causing the leakage of bioactive components such as potassium ion and ß-galactosidase from treated bacterial. Furthermore, PQC sponge can efficiently promote cell proliferation. Significantly, the sponge greatly expedites the regeneration of MRSA-infected full-thickness skin wound in rabbit by successfully eradicating bacterial infection, and reducing inflammation. PQC sponge also improves both early angiogenesis and blood vessel maturation at the wound site. Overall, this multifunctional sponge is a promising wound dressing for clinical use and holds great potential for rapid clinical translation.

Development of injectable thermosensitive polypeptide hydrogel as facile radioisotope and radiosensitizer hotspot for synergistic brachytherapy.

Brachytherapy is considered to be an unparalleled form of conformal radiation therapy, which involves the delivery of radiation directly to tumor lesions or the postoperative cavity. With the development of specific applicators, the exploitation of in situ drug-delivery platform introduces opportunities for the synchronous administration of radiosensitizers. In this study, an iodine-131 (I131)-labeled injectable thermosensitive methoxy poly(ethylene glycol)-b-poly(tyrosine) hydrogel (denoted as PETyr-I131) was developed via a facile method. The radioactive source of I131 was immobilized at the subcutaneous injection site and monitored via single-photon emission computed tomography in real time, and hematological and histopathological analyses revealed no obvious side effects. Additionally, the SmacN7 peptide conjugated with cell membrane-permeable oligosarginine (denoted as SmacN7-R9) was used to enhance the radiosensitivity of cancer cells, as confirmed by the results of reactive oxygen species detection, DNA damage assay, cell apoptosis assay, and clonogenic evaluation. Importantly, a synergistic brachytherapy treatment effect on tumor-bearing nude mice was achieved. The proposed thermosensitive supramolecular hydrogel platform, which conformally immobilizes radionuclides and delivers radiosensitizers by virtue of its proximity to the site of the primary tumor or the postoperative cavity, has great potential for achieving synergistic treatment outcomes with reduced radiation-related side effects. STATEMENT OF SIGNIFICANCE: In this work, a kind of radioiodinated thermosensitive supramolecular hydrogel was developed, which was facilely used as the radioactive source for brachytherapy. Meanwhile, SmacN7-R9 peptide was combined as a model radiosensitizer to facilitate the activation of tumor cell apoptosis pathways and promotion of radiation-induced cytotoxicity. Synergistic brachytherapy outcomes were achieved from the in vitro and in vivo evaluations. Therefore, from the practical standpoint, this thermosensitive supramolecular hydrogel platform holds great potential for the 3D-conformally immobilizing radionuclide and delivering radiosensitizer by virtue of its proximity to the site of primary tumor lesions or postoperative cavity, resulting in synergetic treatment outcomes with reduced radiation associated side effects.

Superhydrophilic fluorinated polymer and nanogel for high-performance 19F magnetic resonance imaging.

19F magnetic resonance imaging (19F MRI), a kind of non-invasive and non-radioactive diagnostic technique with no endogenous background signals, opens up new research avenues for accurate molecular imaging studies. However, 19F MRI is manily limited by the performance of contrast agents. Here, for the first time, we presented the zwitterionic fluorinated polymer and nanogel as new types of superhydrophilic, sensitive and ultra-stable 19F MRI contrast agents. The superhydrophilicity of carboxybetaine zwitterionic structure completely overcame the hydrophobic aggregation-induced signal attenuation associated with amphiphilic fluorinated polymer-based nanoprobes. In addition, the superhydrophilic contrast agent exhibited distinct advantages, including high 19F-content (19.1 wt%), superior resistance to protein adsorption, constant MR properties and 19F MRS-based quantitative determination in complex biological fluids, and intense 19F MRI signals in the whole-body images after intravenous injection. In combination with angiogenesis targeting ligand, the superhydrophilic contrast agent was applied for the unambiguous detection of tumor. Importantly, computational algorithm was established for the directly quantitative determination of bioavailability and tumor-to-whole body ratio (TBR) from the in vivo19F MRI dataset, providing real-time information with non-invasive manner. Finally, crosslinked nanogels were developed with significantly prolonged systemic circulation, of which intense 19F MRI signals nonspecifically distributed in the aortaventralis and blood-rich organs, instead of being trapped steadily in liver as with the state-of-the-art superhydrophobic perfluocarbon nanoemulsions. Overall, this kind of superhydrophilic, zwitterionic fluorinated polymer and nanogel could be defined as a new generation of high-performance 19F MRI contrast agents, which hold great potential for image-based unambiguous disease detection and computational quantification.