Antibody-conjugated and streptomycin-chitosan oligosaccharide-modified gold nanoshells for synergistic chemo-photothermal therapy of drug-resistant bacterial infection.

Despite the many advanced strategies that are available, rapid gene mutation in multidrug-resistant bacterial infections remains a major challenge. Combining new therapeutic strategies such as chemo-photothermal therapy (PTT) with high antibacterial efficiency against drug-resistant Listeria monocytogenes (LM) is urgently needed. Here, we report synergistic chemo-PTT against drug-resistant LM based on antibody-conjugated and streptomycin-chitosan oligosaccharide-modified gold nanoshells (anti-STR-CO-GNSs) as all-in-one nanotheranostic agents for the first time, which was used for accurate antibacterial applications. The anti-STR-CO-GNSs showed excellent photothermal conversion efficiency (31.97 %) and were responsive to near-infrared (NIR) and pH dual stimuli-triggered antibiotic release, resulting in outstanding chemo-photothermal effects against LM. In vitro chemo-photothermal effect of anti-STR-CO-GNSs with laser irradiation caused a greater antibacterial effect (1.37 %), resulting in more rapid killing of LM and prevention of LM regrowth. Most importantly, the mice receiving the anti-STR-CO-GNSs with laser irradiation specifically at the sites of LM infections healed almost completely, leaving only scars on the surface of the skin and resulting in superior inhibitory effects from combined chemo-PTT. Overall, our findings suggest that chemo-PTT using smart biocompatible anti-STR-CO-GNSs is a favorable potential alternative to combat the increasing threat of drug-resistant LM, which opens a new door for clinical anti-infection therapy in the future.

Graphene Oxide-Reinforced Alginate Hydrogel for Controlled Release of Local Anesthetics: Synthesis, Characterization, and Release Studies.

In pain relief, lidocaine has gained more attention as a local anesthetic. However, there are several side effects that limit the use of local anesthetics. Therefore, it is hypothesized that a hydrogel system with facile design can be used for prolonged release of lidocaine. In this study, we developed a formulation comprises of sodium alginate (SA) and graphene oxide (GO) to prolong the release of lidocaine. The gelation was induced by physically crosslinking the alginate with Ca2+ ions. The formation of blank SA and GO-reinforced SA hydrogels was investigated with different concentration of Ca2+ ions. The controlled release of lidocaine hydrochloride (LH) on both hydrogel systems was studied in PBS solution. The GO-reinforced SA hydrogels exhibited more sustained release than SA hydrogels without GO. In vitro biocompatibility test in L929 fibroblast cells confirmed the non-toxic property of hydrogels. Furthermore, to prove the in-situ gelation and biodegradability of hydrogels the hydrogels were injected on mice model and confirmed the stable gel formation. The hydrogels implanted onto the subcutaneous tissue of hydrogels retained over one week. These results indicate that LH-loaded GO-reinforced SA hydrogel can be a potential biomaterial for controlled release of local anesthetics.

Therapeutic effects of boronate ester cross-linked injectable hydrogels for the treatment of hepatocellular carcinoma.

Hepatocellular carcinoma is the most common malignancy with a high incidence rate and is the leading cause of cancer-related deaths. Herein, we developed a thermo-responsive hydrogel comprising poly(ε-caprolactone-co-lactide)-b-poly(ethylene glycol)-b-poly(ε-caprolactone-co-lactide (PCLA) that exhibits acidity-accelerated delivery of the tumor-targeting glucuronic acid-bearing doxorubicin (DOX-pH-GA) conjugate into tumor tissues. The PCLA copolymer was post-modified with boronic acid (BA-PCLA) to covalently cross-link with the pH-responsive DOX-pH-GA conjugate. The BA-PCLA copolymer effectively coordinated with the DOX-pH-GA conjugate through the boronate ester formation and showed a lower critical gelation temperature. The DOX conjugated via boronate ester exhibited a sustained release in vitro. Subcutaneous administration of PCLA copolymers formed in situ gels in the subcutaneous layers of Sprague-Dawley rats and degraded after 6 weeks. Similarly, BA-PCLA copolymers coordinated with DOX-pH-GA formed a stable in situ gel in vivo. In vivo imaging studies demonstrated that DOX-pH-GA was released in a sustained manner. The anti-tumor activity of the DOX releasing injectable hydrogel was examined using a HepG2 liver cancer xenograft model. The in vivo antitumor effect demonstrated that the DOX releasing hydrogel depot remarkably suppresses the tumor growth. These results demonstrate that the pH-responsive DOX releasing thermo-responsive hydrogel depot has great potential for application in localized anticancer therapy.

Modularly engineered alginate bioconjugate hydrogel as biocompatible injectable scaffold for in situ biomineralization.

In the present study, a type of bioconjugate was synthesized by post modification of alginate by conjugating temperature-responsive poly(ε-caprolactone-co-lactide)-b-poly(ethylene glycol)-b-poly(ε-caprolactone-co-lactide) and O-phosphorylethanolamine as phosphorylation functional groups. Freely flowing bioconjugate sols at low temperature can transform to stable viscoelastic gels at the physiological temperature (37 °C). Subcutaneous administration of temperature-responsive bioconjugate sols into the dorsal region of Sprague-Dawley rats formed in situ hydrogel. in situ formation of bioconjugate gels in stimulated body fluids at 37 °C showed nucleation and hydroxyapatite mineral growth. Furthermore, hydroxyapatite growth was also found in in vivo gels, which suggested the potential of alginate-based bioconjugate gels as a scaffold for bone engineering. Bone morphogenetic protein 2 (BMP-2)-loaded bioconjugate formed stable gel in vivo, and demonstrated sustained release. BMP-2-loaded bioconjugates exhibited in situ biomineralization in vivo. These results imply that the in situ formation of injectable biomimetic materials has potential for bone tissue engineering applications.

Smart injectable biogels based on hyaluronic acid bioconjugates finely substituted with poly(ß-amino ester urethane) for cancer therapy.

Development of implantable material to control the release of chemotherapeutics in the body is a promising approach to control cancer cell proliferation; however, implantation requires surgical intervention. Herein, we propose the in situ formation of injectable biogels (IBGs) for the programmed delivery of potent chemotherapeutic drugs. IBGs are developed via cohesive molecular assembly of a polysaccharide-polymer network comprised of hyaluronic acid-poly(ß-amino urethane). Biocompatible IBGs could be administered subcutaneously through a hypodermic needle in vivo to subsequently assemble into a microporous network. The hyaluronic acid-shielded network mimics the natural extracellular matrix, avoiding rapid degradation of IBGs, with a soft texture and adhesiveness facilitating integration with dermal tissues after subcutaneous implantation. The natural-mimicking architecture confers the IBG network controlled degradation and bioresorbable properties. Subcutaneous administration of IBGs controlled the delivery of a therapeutic agent in a spatio-temporal manner. Therapeutic agents delivered near the tumors in a sustained manner were effectively infiltrated into the thick solid tumors and provide a durable and enhanced anti-tumor response in the B16/OVA melanoma model in vivo. These results indicate that IBGs could be potential medical interventions for the treatment of cancers.

Modularly engineered injectable hybrid hydrogels based on protein-polymer network as potent immunologic adjuvant in vivo.

Lymphoid organs, which are populated by dendritic cells (DCs), are highly specialized tissues and provide an ideal microenvironment for T-cell priming. However, intramuscular or subcutaneous delivery of vaccine to DCs, a subset of antigen-presenting cells, has failed to stimulate optimal immune response for effective vaccination and need for adjuvants to induce immune response. To address this issue, we developed an in situ-forming injectable hybrid hydrogel that spontaneously assemble into microporous network upon subcutaneous administration, which provide a cellular niche to host immune cells, including DCs. In situ-forming injectable hybrid hydrogelators, composed of protein-polymer conjugates, formed a hydrogel depot at the close proximity to the dermis, resulting in a rapid migration of immune cells to the hydrogel boundary and infiltration to the microporous network. The biocompatibility of the watery microporous network allows recruitment of DCs without a DC enhancement factor, which was significantly higher than that of traditional hydrogel releasing chemoattractants, granulocyte-macrophage colony-stimulating factor. Owing to the sustained degradation of microporous hydrogel network, DNA vaccine release can be sustained, and the recruitment of DCs and their homing to lymph node can be modulated. Furthermore, immunization of a vaccine encoding amyloid-ß fusion proteinbearing microporous network induced a robust antigen-specific immune response in vivo and strong recall immune response was exhibited due to immunogenic memory. These hybrid hydrogels can be administered in a minimally invasive manner using hypodermic needle, bypassing the need for cytokine or DC enhancement factor and provide niche to host immune cells. These findings highlight the potential of hybrid hydrogels that may serve as a simple, yet multifunctional, platform for DNA vaccine delivery to modulate immune response.

Smart vaccine delivery based on microneedle arrays decorated with ultra-pH-responsive copolymers for cancer immunotherapy.

Despite the tremendous potential of DNA-based cancer vaccines, their efficacious delivery to antigen presenting cells to stimulate both humoral and cellular response remains a major challenge. Although electroporation-based transfection has improved performance, an optimal strategy for safe and pain-free vaccination technique remains elusive. Herein, we report a smart DNA vaccine delivery system in which nanoengineered DNA vaccine was laden on microneedles (MNs) assembled with layer-by-layer coating of ultra-pH-responsive OSM-(PEG-PAEU) and immunostimulatory adjuvant poly(I:C), a synthetic double stranded RNA. Transcutaneous application of MN patches onto the mice skin perforate the stratum corneum with minimal cell damage; subsequent disassembly at the immune-cell-rich epidermis/dermis allows the release of adjuvants and DNA vaccines, owing to the ultra-sharp pH-responsive nature of OSM-(PEG-PAEU). The released adjuvant and DNA vaccine can enhance dendritic cell maturation and induce type I interferons, and thereby produce antigen-specific antibody that can achieve the antibody-dependent cell-mediated cytotoxicity (ADCC) and CD8+ T cell to kill cancer cells. Strikingly, transcutaneous application of smart vaccine formulation in mice elicited 3-fold greater frequencies of Anti-OVA IgG1 serum antibody and 3-fold excess of cytotoxic CD8+ T cell than soluble DNA vaccine formulation. As a consequence, the formulation rejected the murine B16/OVA melanoma tumors in C57BL/6 mice through the synergistic activation of antigen-specific ADCC and cytotoxic CD8+ T cells. The maneuvered use of vaccine and adjuvant poly(I:C) in MNs induces humoral and cellular immunity, which provides a promising vaccine technology that shows improved efficacy, compliance, and safety.

Bioinspired pH- and Temperature-Responsive Injectable Adhesive Hydrogels with Polyplexes Promotes Skin Wound Healing.

Despite great potential, the delivery of genetic materials into cells or tissues of interest remains challenging owing to their susceptibility to nuclease degradation, lack of permeability to the cell membrane, and short in vivo half-life, which severely restrict their widespread use in therapeutics. To surmount these shortcomings, we developed a bioinspired in situ-forming pH- and temperature-sensitive injectable hydrogel depot that could control the delivery of DNA-bearing polyplexes for versatile biomedical applications. A series of multiblock copolymer, comprised of water-soluble poly(ethylene glycol) (PEG) and pH- and temperature-responsive poly(sulfamethazine ester urethane) (PSMEU), has been synthesized as in situ-forming injectable hydrogelators. The free-flowing PEG-PSMEU copolymer sols at high pH and room temperature (pH 8.5, 23 °C) were transformed to stable gel at the body condition (pH 7.4, 37 °C). Physical and mechanical properties of hydrogels, including their degradation rate and viscosity, are elegantly controlled by varying the composition of urethane ester units. Subcutaneous administration of free-flowing PEG-PSMEU copolymer sols to the dorsal region of Sprague-Dawley rats instantly formed hydrogel depot. The degradation of the hydrogel depot was slow at the beginning and found to be bioresorbable after two months. Cationic protein or DNA-bearing polyplex-loaded PEG-PSMEU copolymer sols formed stable gel and controlled its release over 10 days in vivo. Owing to the presence of urethane linkages, the PEG-PSMEU possesses excellent adhesion strength to wide range of surfaces including glass, plastic, and fresh organs. More importantly, the hydrogels effectively adhered on human skin and peeled easily without eliciting an inflammatory response. Subcutaneous implantation of PEG-PSMEU copolymer sols effectively sealed the ruptured skin, which accelerated the wound healing process as observed by the skin appendage morphogenesis. The bioinspired in situ-forming pH- and temperature-sensitive injectable adhesive hydrogel may provide a promising platform for myriad biomedical applications as controlled delivery vehicle, adhesive, and tissue regeneration.

Microneedle arrays coated with charge reversal pH-sensitive copolymers improve antigen presenting cells-homing DNA vaccine delivery and immune responses.

Successful delivery of a DNA vaccine to antigen-presenting cells and their subsequent stimulation of CD4+ and CD8+ T cell immunity remains an inefficient process. In general, the delivery of prophylactic vaccines is mainly mired by low transfection efficacy, poor immunogenicity, and safety issues from the materials employed. Currently, several strategies have been exploited to improve immunogenicity, but an effective strategy for safe and pain-free delivery of DNA vaccines is complicated. Herein, we report the rapid delivery of polyplex-based DNA vaccines using microneedle arrays coated with a polyelectrolyte multilayer assembly of charge reversal pH-responsive copolymer and heparin. The charge reversal pH-responsive copolymer, composed of oligo(sulfamethazine)-b-poly(ethylene glycol)-b-poly(amino urethane) (OSM-b-PEG-b-PAEU), was used as a triggering layer in the polyelectrolyte multilayer assembly on microneedles. Charge reversal characteristics of this copolymer, that is, the OSM-b-PEG-b-PAEU copolymer exhibit, positive charge at low pH (pH4.03) and becoming negative charge when exposed to physiological pH conditions (pH7.4), allowing the facile assembly and disassembly of polyelectrolyte multilayers. The electrostatic repulsion between heparin and OSM-b-PEG-b-PAEU charge reversal copolymer triggered the release of DNA vaccines. DNA vaccines laden on microneedles are effectively transfected into RAW 264.7 macrophage cells in vitro. Vaccination of BALB/c mice by DNA vaccine-loaded microneedle arrays coated with a polyelectrolyte multilayer generated antigen-specific robust immune responses. These findings provide potential strategy of charge reversal pH-responsive copolymers coated microneedles for DNA vaccine delivery.

Bioengineered robust hybrid hydrogels enrich the stability and efficacy of biological drugs.

Biological drugs are exquisitely tailored components offering the advantages of high specificity and efficacy that are considered safe for treating diseases. Nevertheless, the effectiveness of biological drugs is limited by their inherent short biological half-life and poor stability in vivo. Herein, we engineered a novel delivery platform based on hybrid injectable hydrogels, in which pH- and temperature-responsive biodegradable copolymers were site-specifically coupled to the sulfhydryl group of human serum albumin, which effectively enhances the stability and circulation half-life of the biological drug, recombinant uricase enzyme (Uox). The albumin ligand conjugated to the Uox allowed specific-binding of the enzyme within the protein shell, and the synthetic polymers effectively shield the protein-enzyme complex. Such close confinement exhibits strong resistance towards various physical, chemical and therapeutically relevant stressors such as temperature, pH and proteases. Subcutaneous administration of Uox-loaded bioengineered hybrid hydrogel improved the pharmacokinetics by prolonging its circulation half-life. As a consequence, the bioengineered hybrid hydrogel normalized the serum uric acid level in hypoxanthine/potassium oxonate-induced hyperuricemia mice, and no obvious side effects were observed in the major organs. The characteristic of the bioengineered hydrogel networks applicable to a variety of biological drugs by simple mixing that unlock the possibility of adapting biological drugs to therapeutic applications.