Self-healing hydrogel based on poly (vinyl alcohol)-poly (lysine)-gum arabic accelerates diabetic wound healing under photothermal sterilization.

Diabetic wounds are a significant clinical challenge. Developing effective antibacterial dressings is crucial for preventing wound ulcers caused by bacterial infections. In this study, a self-healing antibacterial hydrogel (polyvinyl alcohol (PVA)-polylysine-gum arabic, PLG hydrogels) with near-infrared photothermal response was prepared by linking PVA and a novel polysaccharide-amino acid compound (PG) through borate bonding combined with freeze-thaw cycling. Subsequently, the hydrogel was modified by incorporating inorganic nanoparticles (modified graphene oxide (GM)). The experimental results showed that the PLGM3 hydrogels (PLG@GM hydrogels, 3.0 wt%) could effectively kill bacteria and promote diabetic wound tissue healing under 808-nm near-infrared laser irradiation. Therefore, this hydrogel system provides a new idea for developing novel dressings for treating diabetic wounds.

An NIR light-driven AgBiS2@ZIF-8 hybrid photocatalyst for rapid bacteria-killing.

Bacterial infection is the most common risk factor that causes the failure of implantation surgery. Therefore, the development of biocompatible implants with excellent antibacterial properties is of utmost importance. In this study, NIR light-driven AgBiS2@ZIF-8 hybrid photocatalysts for rapid bacteria-killing were prepared. AgBiS2@ZIF-8 exhibited excellent photocatalytic activity due to the rapid transfer of photoelectrons from AgBiS2 to ZIF-8, resulting in abundant reactive oxygen species (ROS) to kill bacteria. Meanwhile, AgBiS2@ZIF-8 exhibited a noteworthy photothermal effect, which could effectively convert NIR light into heat. Subsequently, the NIR light-driven antibacterial activity of AgBiS2@ZIF-8/Ti against S. aureus and E. coli was studied. The experimental results showed that AgBiS2@ZIF-8 displayed enhanced photodynamic therapy (PDT) and photothermal therapy (PTT) performance. Under irradiation with 808 nm NIR light for 10 min, AgBiS2@ZIF-8/Ti could effectively eliminate 98.55% of S. aureus in vitro, 99.34% of E. coli in vitro and 95% S. aureus in vivo. At the same time, AgBiS2@ZIF-8/Ti had good biocompatibility. Therefore, AgBiS2@ZIF-8/Ti showed potential as an antibacterial material, which provided a strategy to fight polymicrobial infections.

AgBiS2@CQDs/Ti nanocomposite coatings for combating implant-associated infections by photodynamic /photothermal therapy.

Biofilm-mediated implant-associated infections are one of the most serious complications of implantation surgery, posing a grave threat to patient well-being. Effectively addressing bacterial infections is crucial for the success of implantation procedures. In this study, we prepared a bismuth sulfide silver@carbon quantum dot composite coating (AgBiS2@CQDs/Ti) on a medical titanium surface by surface engineering design to treat implant-associated infections. The photocatalytic/photothermal activity test results confirmed the excellent photogenerated ROS and photothermal properties of AgBiS2@CQDs/Ti under near-infrared laser irradiation. In vitro antibacterial and in vivo anti-infection experiments showed that the coating combined with photodynamic and photothermal therapies to eradicate bacteria and disrupt mature biofilms under 1064 nm laser irradiation. Consequently, AgBiS2@CQDs/Ti shows promise as an implant coating for treating implant-associated infections post-surgery, thereby enhancing the success rate of implantation procedures. This study also provides a new idea for combating implant-associated infections.

Silk fibroin-based coating with pH-dependent controlled release of Cu2+ for removal of implant bacterial infections.

The implantation of medical devices is frequently accompanied by the invasion of bacteria, which may lead to implant failure. Therefore, an intelligent and responsive coating seems particularly essential in hindering implant-associated infections. Herein, a self-defensive antimicrobial coating, accompanied by silk fibroin as a valve, was successfully prepared on the titanium (Ti-Cu@SF) for pH-controlled release of Cu2+. The results showed that the layer could set free massive Cu2+ to strive against E. coli and S. aureus for self-defense when exposed to a slightly acidic condition. By contrary, a little Cu2+ was released in the physiological situation, which could avoid damage to the normal cells and showed excellent in vitro pH-dependent antibiosis. Besides, in vivo experiment confirmed that Ti-Cu@SF could work as an antibacterial material to kill S. aureus keenly and display negligible toxicity in vivo. Consequently, the design provided support for endowing the layer with outstanding biocompatibility and addressing the issue of bacterial infection during the implantation of Ti substrates.

Fabrication of graphene oxide/copper synergistic antibacterial coating for medical titanium substrate.

Titanium (Ti) was an excellent medical metal material, but the lack of good antibacterial activity confined its further practical application. To solve this dilemma, a coating containing graphene oxide (GO) and copper (Cu) was prepared on the surface of Ti sheet (Ti/APS/GO/Cu). First, physical sterilization could be carried out through the sharp-edged sheet structure of GO. Second, the oxygen-containing functional group on the surface of GO and the released Cu2+ would generate reactive oxygen species for chemical sterilization. The synergistic effect of GO and Cu substantially enhanced the in vitro and in vivo antibacterial property of Ti sheet, thereby reducing bacterial-related inflammation. Quantitatively, the antibacterial rate of Ti/APS/GO/Cu against E. coli or S. aureus reached over 99%. Besides, Ti/APS/GO/Cu showed excellent biocompatibility and no toxicity to cell. Such work developed multiple sterilization avenues to design non-antibiotic, safe and efficient antibacterial implant material for the biomedical domain.

Pt-Quantum-Dot-Modified Sulfur-Doped NiFe Layered Double Hydroxide for High-Current-Density Alkaline Water Splitting at Industrial Temperature.

Suitable electrocatalysts for industrial water splitting can veritably promote practical hydrogen applications. Rational surface design is exceptionally significant for electrocatalysts to bridge the gap between fundamental science and industrial expectation in water splitting. Here, Pt-quantum-dot-modified sulfur-doped NiFe layered double hydroxides (Pt@S-NiFe LDHs) are designed with eximious catalytic activity toward hydrogen evolution reaction (HER) under industrial condition. Benefiting from enhanced binding energy, mass transfer, and hydrogen release, Pt@S-NiFe LDHs exhibit outstanding activity in HER at high current densities. Notably, it obtains an impressively low overpotential of 71 mV and long-term stability of 200 h at 100 mA cm-2 , exceeding commercial 40% Pt/C and most reported Pt-based electrocatalysts. Its mass activity is 2.7 times higher than that of 40% Pt/C with an overpotential of 100 mV. Furthermore, at industrial temperature (65 °C), the electrolyzer based on Pt@S-NiFe LDH needs just 1.62 V to reach the current density of 100 mA cm-2 , superior to that of the commercial one of 40% Pt/C//IrO2 . This work provides rational ideas to develop electrocatalysts with exceptional performance for industrial high-temperature water splitting at high current densities.

Fabrication of a TiO2@Cu Core-Shell Nanorod Array as Coating for Titanium Substrate with Mechanical and Chemical Dual Antibacterial Property.

Titanium (Ti) is an excellent medical metal material, but the absence of good antibacterial property restricts its widespread application. To overcome this, we thus conducted a series of modifications for Ti. First, a titanium dioxide (TiO2) nanorod array was generated on the Ti surface by hydrothermal treatment (TiO2/Ti). With the polymer-mediated self-assembly method, a continuous copper (Cu) shell structure on the surface of the nanorod was then generated to form a TiO2@Cu core-shell nanorod array as coating for Ti (TiO2@Cu/Ti). Using pure Ti as the control group, the antibacterial properties of TiO2/Ti and TiO2@Cu/Ti were appraised. The results manifested that the mechanical and chemical dual function of the released Cu2+ and TiO2 nanorod array could effectively kill bacteria on the surface of Ti. Besides, the obtained coating exhibited no cytotoxicity and favorable biocompatibility. In this work, we found an antibacterial strategy based on multiple sterilization pathways, which made Ti have good antibacterial property and further improved its biocompatibility.

Implanting a Copper Ion into a TiO2 Nanorod Array for the Investigation on the Synergistic Antibacterial Mechanism between Mechanical Cracking and Chemical Damage.

Titanium (Ti) and its alloys are extensively applied in dental and orthopedic implants due to their characteristics of good mechanical property and corrosion resistance. However, Ti and its alloys suffer from the absence of certain biological activity and antibacterial ability. Herein, we synthesized a titanium dioxide (TiO2) nanorod array on the surface of a Ti plate, and the obtained TiO2 nanorod array was further modified by Cu ions through ion implantation technology in an attempt to endow medical Ti with an antibacterial ability and maintain a normal biological function synchronously. The antibacterial ability of the TiO2 nanorod array with the incorporation of Cu ions was vastly improved compared with those of the unmodified TiO2 nanorod array and pure Ti. In particular, owing to the synergy between the chemical damage of the released Cu2+ to the cell and the mechanical cracking of the TiO2 nanorod array, the antibacterial rate of the TiO2 nanorod array modified by Cu ions against Escherichia coli or Staphylococcus aureus could reach 99%. In addition, no cytotoxicity was detected in such prepared coating during the CCK-8 assay. Moreover, the corrosion resistance of the sample was significantly better than that of pure Ti. Overall, we demonstrated that the application of ion implantation technology could open up a promising pathway to design and develop further antibacterial material for the biomedical domain.

Fabrication of Laponite-Reinforced Dextran-Based Hydrogels for NIR-Responsive Controlled Drug Release.

Natural polymer gels with sensitivity to near-infrared (NIR) light have attracted the attention of scientists working on intelligent drug delivery systems. Compared to ultraviolet or visible light, NIR light has the advantages of strong trigger levels, deep penetration through affected tissues, and fewer side effects. Herein, we present a topical photothermal hydrogel for NIR-controlled drug delivery. The proposed DexIEM-GM-Laponite hydrogel was prepared through free radical polymerization of vinyl-functionalized dextran (DexIEM), vinyl-modified graphene oxide (GM), and Laponite; thereafter, the hydrogel was loaded with ciprofloxacin (CIP, an antibacterial drug) as a model drug. With the Laponite content increased, the density of crosslinking in the hydrogel increased, and its mechanical properties improved noticeably. Under NIR irradiation, the DexIEM-GM-Laponite hydrogel exhibited a photothermal property, where the surface temperature increased from 26.8 to 55.5 °C. The simulation of subcutaneous drug delivery experiments ex vivo showed that under the specified pork tissue thickness (2, 4, and 6 mm), the CIP release remained NIR-controllable. Additionally, the results of the antibacterial performance tests indicated the excellent antibacterial effect of the hydrogel, and the blood hemolysis ratio of the hydrogel was less than 5%, signifying good blood compatibility. This work will provide an avenue for the application of NIR light-responsive materials in antimicrobial therapy.

Bio-Based Aerogel Based on Bamboo, Waste Paper, and Reduced Graphene Oxide for Oil/Water Separation.

In recent years, the discharge of industrial waste oil has increased and offshore oil leakage has occurred frequently, and thus water pollution has become a worldwide problem that attracts much attention. In this regard, a kind of oil-absorbing material with high oil-absorbing property and good mechanical property is urgently needed. Here, we reported a new type of aerogels with three-dimensional layered voids using natural bamboo powder, waste paper (WP), and graphene oxide (GO) as raw materials. The obtained aerogel had high adsorption capacity (87-121 g/g), compressibility, and high elasticity, which can separate oil from water and selectively absorb oil. This study provides not only a new treatment in agricultural waste treatment but also a facile, green, and low-cost approach to synthesize high-performance graphene-based oil absorbers, which might give us an effective solution for oil pollution of water resources worldwide.

A novel Janus sponge fabricated by a green strategy for simultaneous separation of oil/water emulsions and dye contaminants.

A novel Janus sponge with the ability to remove complex contaminants from water is reported. Firstly, a superhydrophilic sponge (PA@PEI-sponge) is prepared via synthesizing negatively charged phytic acid@polyethyleneimine (PA@PEI) nanoparticles and assembling them on the surface of polydopamine (PDA) and PEI-modified polyurethane (PU) sponge through electrostatic adsorption. The Janus sponge is generated by modifying one side of the PA@PEI-sponge with PDMS, which exhibits superior separation efficiency and high filtration flux toward both water-in-oil and oil-in-water emulsions due to its multiplex selective wettability and the interconnected and tortuous 3D porous channels. The numerous negatively charged active sites of PA@PEI nanoparticles and PDA layer impart the superhydrophilic PA@PEI-sponge with the removal efficiency of 39.95 ± 0.27% for malachite green (MG) via simple flow-through filtration, which can be improved to 99.92 ± 0.07% by Janus modification. More importantly, the Janus sponge exhibits an excellent treatment capacity for complex mixtures containing emulsified oil and dye, with the separation efficiency above 99.59%. The Janus sponge also demonstrates the effective separation of real industrial wastewater collected from an acrylic dyeing plant. Together with a facile and green preparation strategy, this Janus sponge shows excellent application potential for simultaneous dye removal and oil/water emulsion separation.

Preparation of silane-dispersed graphene crosslinked vinyl carboxymethyl chitosan temperature-responsive hydrogel with antibacterial properties.

We synthesized a temperature-sensitive antibacterial hydrogel, defined as NIPAM-CG/GM hydrogel. First, vinyl carboxymethyl chitosan (CG) was synthesized as a crosslinking carrier and silane dispersed graphene (GM) was synthesized as a reinforcer. Then, the N-isopropylacrylamide (NIPAM) monomer was free-radical polymerized with the vinyl groups of CG and GM to form a NIPAM-CG/GM hydrogel without any crosslinking agent. The influences of different hydrogel compositions on the microstructure, compressive properties, swelling, drug loading, and drug release properties of the hydrogels were discussed, and its temperature sensitivity was also demonstrated. The results showed that the lower critical solution temperature (LCST) and mechanical properties of the hydrogel could be adjusted by controlling the amount of CG and GM. Next, its biocompatibility was characterized, and its antibacterial performance was tested against Escherichia coli and Staphylococcus aureus. The antibacterial mechanism was explained by measuring the difference in the ion concentration outside the membrane and changes in the morphology of live/dead bacteria. NIPAM-CG/GM had a high drug loading and nearly complete drug release at a physiological temperature of 37 °C. Its moderate mechanical properties, excellent biocompatibility, and antibacterial effects give NIPAM-CG/GM great potential applications as a wound dressing.

Mechanism Insight into Rapid Photodriven Sterilization Based on Silver Bismuth Sulfide Quantum Dots.

Microbial contamination and the prevalence of resistant bacteria is considered a worldwide public health problem. Therefore, recently, great efforts have been made to develop photoresponsive platforms for the simultaneous photodynamic antibacterial (PDA) and photothermal antibacterial (PTA) therapy processes as mediated by specific light. However, owing to the absorption mismatches of the photothermal agents and photodynamic photosensitizers, it has been discovered that many synergistic photoresponsive antibacterial platforms cannot be excited by a single-wavelength light. In this study, silver bismuth sulfide quantum dots (AgBiS2 QDs) identified from the literature as a near-infrared light (NIR) that triggers bifunctional materials with simultaneous photodynamic and photothermal effects for photoresponsive bacterial killing were used. Specifically, AgBiS2 QDs were successfully synthesized via a bottom-up approach, using polyethylenimine (PEI) as an assistant molecule. With PEI wrapping, the attachment between the negatively charged membrane surfaces of the bacterial cells and AgBiS2 QDs was enhanced via the electrostatic interactions. The photodriven antibacterial activity of AgBiS2 QDs was then investigated against both S. aureus and E. coli. The results revealed a significant reduction in bacterial survival. The killing effect was found to be independent of the AgBiS2 QDs, and redox potentials controlled the photogenerated electrons that thermodynamically favored the formation of multiple reactive oxygen species (ROS). A possible phototriggered antibacterial mechanism was then proposed in which the AgBiS2 QDs are anchored first to the bacterial surface and then induce breaking on its outer membrane by high local heat and ROS under single 808 nm NIR laser illumination to finally induce bacterial death.

Preparation and Antimicrobial Activity of Antibacterial Silver-Loaded Polyphosphazene Microspheres.

Poly(cyclotriphosphazene-co-4,4'-diaminodiphenyl ether) (PPO) microspheres were prepared via a precipitation polymerization method, using hexachlorocyclotriphosphazene (HCCP) and 4,4'-diaminodiphenyl ether (ODA) as monomers. Silver-loaded PPO (PPOA) microspheres were generated by the in situ loading of silver nanoparticles onto the surface by Ag+ reduction. Our results showed that PPOA microspheres were successfully prepared with a relatively uniform distribution of silver nanoparticles on microsphere surfaces. PPOA microspheres had good thermal stability and excellent antibacterial activity towards Escherichia coli and Staphylococcus aureus. Furthermore, PPOA microspheres exhibited lower cytotoxicity when compared to citrate-modified silver nanoparticles (c-Ag), and good sustained release properties. Our data indicated that polyphosphazene-based PPOA microspheres are promising antibacterial agents in the biological materials field.

High-Performance Three-Dimensional Aerogel Based on Hydrothermal Pomelo Peel and Reduced Graphene Oxide as an Efficient Adsorbent for Water/Oil Separation.

In this study, HPP-RGO aerogels, which were based on a hydrothermal pomelo peel (HPP) and reduced graphene oxide (RGO), were fabricated by using a green and eco-friendly two-step hydrothermal method. The characterization results showed that the HPP-RGO aerogel was endowed with extremely low density, high specific area, robust thermal stability, good mechanical property, stable acid-alkali resistance, superior recyclability, and excellent hydrophobicity and lipophilicity. Remarkably, the typical 40%-HPP-RGO aerogel presented a preferable adsorption capacity (45-80 g·g-1). Moreover, continuous water/oil separation was achieved via the water ring vacuum pump. The successful preparation of the HPP-RGO aerogel endows the pomelo peel with high value-added properties and improves the comprehensive utilization of agricultural wastes. Furthermore, it would open up bright prospects for the field of oil adsorption and water/oil separation.

Fabrication of a Cu Nanoparticles/Poly(ε-caprolactone)/Gelatin Fiber Membrane with Good Antibacterial Activity and Mechanical Property via Green Electrospinning.

To improve the antibacterial effect of a poly(ε-caprolactone)/gelatin (PCL/Gt) composite, Cu nanoparticles (Cu NPs) were synthesized as an antibacterial agent, and a Cu NPs/PCL/Gt fiber membrane was thus fabricated via green electrospinning. The results showed that the Cu NPs/PCL/Gt fiber membrane with a uniform and complete structure exhibited high porosity and water absorption, favorable hydrophilicity, good mechanical and thermal properties, and satisfactory antibacterial activity. The easy preparation and good comprehensive property implied the great potential application of the Cu NPs/PCL/Gt fiber membrane in various fields (e.g., wound dressing and antibacterial clothing). In addition, the synthesis in this work would offer a promising approach for the preparation of a metal nanoparticle/polymer fiber material with good antibacterial property.

Strongly Coupled NiCo2O4 Nanocrystal/MXene Hybrid through In Situ Ni/Co-F Bonds for Efficient Wearable Zn-Air Batteries.

Recently, owing to the high energy density and excellent security, wearable Zn-air batteries (ZABs) have been known as one of the most prominent wearable energy storage devices. However, sluggish oxygen reaction kinetics of oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) in the air-breathe cathode seriously has limited further practical applications. In this work, we synthesize a NiCo2O4 nanocrystal/MXene hybrid with strong Ni/Co-F bonds. The prepared MXene-based hybrid composites show remarkable ORR and OER electrocatalytic activity, which results in the fabricated solid-state ZAB device to achieve an open-circuit voltage of 1.40 V, peak power density of 55.1 mW cm-2, and energy efficiency of 66.1% at 1.0 mA cm-2; to the best of our knowledge, this is the record performance among all reported flexible ZABs with MXene-based air cathodes and comparable with some noble metal catalysts. Moreover, even after cutting and suturing, our flexible solid-state ZAB devices are tailorable with high rate of performance.

Dual-Function Antibacterial Micelle via Self-Assembling Block Copolymers with Various Antibacterial Nanoparticles.

Antibacterial biomaterials with kill-resist dual functions by combining multiple active components have been constructed, with a final aim at decreasing the incidence of biomaterial-centered infection. Self-assemblies of bactericidal ZnO or Ag-ZnO nanoparticles (NPs) with triblock copolymers, poly(ethylene glycol)-b-poly(3-hydroxybutyrate-co-3-hydroxyvalerate)-poly(ethylene glycol) (PEG-PHBV-PEG), showed a hydrophobic PHBV layer on NPs with PEG segments exposed outside via hydrogen bonding, resulting in long PEG (M w = 2000) aggregation and short PEG (M w = 1000) aggregation, respectively. These nanocomposite aggregations released ZnO or Ag-ZnO rapidly within initial few hours, and about 42-45% of NPs were left in the nanocomposites in deionized water for 16 d to improve the long-term antibacterial activity further. At the concentration below 50 µg/mL, the nanocomposite aggregation was cell-compatible with ATDC5 and showed sterilization rates over 91% against Escherichia coli and 98% against Staphylococcus aureus. Long PEG aggregation showed greater cell proliferation capacity than short PEG aggregation, as well as better bacterial resistance and bactericidal activity against both E. coli and S. aureus. The flexible self-assembling antibacterial NPs with antifouling block copolymers via adjusting the component ratio or the segment length have shown premise in the construction of the dual-function antibacterial materials.

Cetylpyridinium bromide/montmorillonite-graphene oxide composite with good antibacterial activity.

In this study, a cetylpyridinium bromide (CPB)/montmorillonite-graphene oxide (GM) composite (GM-CPB) was prepared by loading CPB in a carrier of GM. The chemical structure, elemental composition, morphology, thermogravimetric analysis, antibacterial activity, sustained release property and cytotoxicity were analyzed. The loading rate of CPB in a GM carrier was higher than that of the graphene oxide (GO) carrier under the same loading condition. The antibacterial activity and sustained release performance of GM-CPB were also better than that of GO-CPB; furthermore, GM-CPB showed lower cytotoxicity than CPB.

Graphene Oxide-IPDI-Ag/ZnO@Hydroxypropyl Cellulose Nanocomposite Films for Biological Wound-Dressing Applications.

In this work, we proposed a feasible approach to prepare multifunctional composite films by introducing a nanoscaled filler into a polymer matrix. Specifically, thanks to isophorone diisocyanate (IPDI) acting as a coupling agent, the hydroxyl groups and carboxyl groups on the surface of graphene oxide (GO) and the hydroxyl groups on the surface of silver-coated zinc oxide nanoparticles (Ag/ZnO) are covalently grafted, forming GO-IPDI-Ag/ZnO (AGO). The prepared AGO was then introduced into the hydroxypropyl cellulose (HPC) matrix to form AGO@HPC nanocomposite films by solution blending. AGO@HPC nanocomposite films exhibited improved mechanical, anti-ultraviolet, and antibacterial properties. Specifically, a tensile test showed that the tensile strength of the prepared AGO@HPC nanocomposite film with the addition of as low as 0.5 wt % AGO was increased by about 16.2% compared with that of the pure HPC film. In addition, AGO@HPC nanocomposite films showed a strong ultraviolet resistance and could effectively inactivate both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria at a low loading of AGO, and rapid sterilization plays a crucial role in wound-healing. In vivo results show that the AGO@HPC release of Ag+ and Zn2+ stimulates the immune function to produce a large number of white blood cells and neutrophils, thereby producing the synergistic antibacterial effects and accelerated wound-healing. Therefore, our results suggest that these novel AGO@HPC nanocomposite films with improved mechanical, anti-ultraviolet, and antibacterial properties could be promising candidates for antibacterial packaging, biological wound-dressing, etc. The abuse of antibiotics has brought about serious drug-resistant bacteria, and our nanofilm antibacterial does not entail such problems. In addition, local administration reduces the possibility of changing the body's immune system and organ toxicity, which greatly increases the safety.