Tuning Electrocatalytic Activities of Dealloyed Nanoporous Catalysts by Macroscopic Strain Engineering.

It is technically challenging to quantitatively apply strains to tune catalysis because most heterogeneous catalysts are nanoparticles, and lattice strains can only be applied indirectly via core-shell structures or crystal defects. Herein, we report quantitative relations between macroscopic strains and hydrogen evolution reaction (HER) activities of dealloyed nanoporous gold (NPG) by directly applying macroscopic strains upon bulk NPG. It was found that macroscopic compressive strains lead to a decrease, while macroscopic tensile strains improve the HER activity of NPG, which is in line with the d-band center model. The overpotential and onset potential of HER display approximately a linear relation with applied macroscopic strains, revealing an ∼2.9 meV decrease of the binding energy per 0.1% lattice strains from compressive to tensile. The methodology with the high strain sensitivity of electrocatalysis, developed in this study, paves a new way to investigate the insights of strain-dependent electrocatalysis with high precision.

A Smart Bacteria-Capture-Killing Vector for Effectively Treating Osteomyelitis Through Synergy Under Microwave Therapy.

Osteomyelitis caused by deep tissue infections is difficult to cure through phototherapy due to the poor penetration depth of the light. Herein, Cu/C/Fe3O4-COOH nanorod composites (Cu/C/Fe3O4-COOH) with nanoscale tip convex structures are successfully fabricated as a microwave-responsive smart bacteria-capture-killing vector. Cu/C/Fe3O4-COOH exhibited excellent magnetic targeting and bacteria-capturing ability due to its magnetism and high selectivity affinity to the amino groups on the surface of Staphylococcus aureus (S. aureus). Under microwave irradiation, Cu/C/Fe3O4-COOH efficiently treated S. aureus-infected osteomyelitis through the synergistic effects of microwave thermal therapy, microwave dynamic therapy, and copper ion therapy. It is calculated the electric field intensity in various regions of Cu/C/Fe3O4-COOH under microwave irradiation, demonstrating that it obtained the highest electric field intensity on the surface of copper nanoparticles of Cu/C/Fe3O4-COOH due to its high-curvature tips and metallic properties. This led to copper nanoparticles attracted more charged particles compared with other areas in Cu/C/Fe3O4-COOH. These charges are easier to escape from the high curvature surface of Cu/C/Fe3O4-COOH, and captured by adsorbed oxygen, resulting in the generation of reactive oxygen species. The Cu/C/Fe3O4-COOH designed in this study is expected to provide insight into the treatment of deep tissue infections under the irradiation of microwave.

Natural Extracts for Antibacterial Applications.

Bacteria-induced epidemics and infectious diseases are seriously threatening the health of people around the world. In addition, antibiotic therapy has been inducing increasingly more serious bacterial resistance, which makes it urgent to develop new treatment strategies to combat bacteria, including multidrug-resistant bacteria. Natural extracts displaying antibacterial activity and good biocompatibility have attracted much attention due to greater concerns about the safety of synthetic chemicals and emerging drug resistance. These antibacterial components can be isolated and utilized as antimicrobials, as well as transformed, combined, or wrapped with other substances by using modern assistive technologies to fight bacteria synergistically. This review summarizes recent advances in natural extracts from three kinds of sources-plants, animals, and microorganisms-for antibacterial applications. This work discusses the corresponding antibacterial mechanisms and the future development of natural extracts in antibacterial fields.

Electron Aggregation and Oxygen Fixation Reinforced Microwave Dynamic and Thermal Therapy for Effective Treatment of MRSA-Induced Osteomyelitis.

Antibiotics are frequently used to clinically treat osteomyelitis caused by bacterial infections. However, extended antibiotic use may result in drug resistance, which can be life threatening. Here, a heterojunction comprising Fe2O3/Fe3S4 magnetic composite is constructed to achieve short-term and efficient treat osteomyelitis caused by methicillin-resistant Staphylococcus aureus (MRSA). The Fe2O3/Fe3S4 composite exhibits powerful microwave (MW) absorption properties, thereby effectively converting incident electromagnetic energy into thermal energy. Density functional theory calculations demonstrate that Fe2O3/Fe3S4 possesses significant charge accumulation and oxygen-fixing capacity at the heterogeneous interface, which provides more active sites and oxygen sources for trapping electromagnetic hotspots. The finite element analysis indicates that Fe2O3/Fe3S4 displays a larger electromagnetism field enhancement parameter than Fe2O3 owing to a significant increase in electromagnetic hotspots. These hotspots contribute to charge differential accumulation and depletion motions at the interface, thereby augmenting the release of free electrons that subsequently combine with the oxygen adsorbed by Fe2O3/Fe3S4 to generate reactive oxygen species (ROS) and heat. This research, which achieves extraordinary bacterial eradication through the synergistic effect of microwave thermal therapy (MWTT) and microwave dynamic therapy (MDT), presents a novel strategy for treating deep-tissue bacterial infections.

Dual Redox Reaction Sites for Pseudocapacitance Based on Ti and -P Functional Groups of Ti3C2PBrx MXene.

MXenes have extensive applications due to their different properties determined by intrinsic structures and various functional groups. Exploring different functional groups of MXenes leads to improved performance or potential applications. In this work, we prepared new Ti3C2PBrx (x=0.4-0.6) MXene with phosphorus functional groups (-P) through a two-step gas-phase reaction. The acquisition of -P is achieved by replacing bromine functional groups (-Br) of Ti3C2Br2 in the phosphorus vapor. After -Br is replaced with -P, Ti3C2PBrx MXene shows an improved areal capacitance (360 mF cm-2) at 20 mV s-1 compared with Ti3C2Br2 MXene (102 mF cm-2). At a current density of 5 mA cm-2 after 10000 cycles, the capacitance retention of Ti3C2PBrx MXene has not decreased. The pseudocapacitive enhancement mechanism has been discovered based on the dual redox sites of the functional groups -P and Ti.

Metal Ion Coordination Improves Graphite Nitride Carbon Microwave Therapy in Antibacterial and Osteomyelitis Treatment.

The ability to effectively treat deep bacterial infections while promoting osteogenesis is the biggest treatment demand for diseases such as osteomyelitis. Microwave therapy is widely studied due to its remarkable ability to penetrate deep tissue. This paper focuses on the development of a microwave-responsive system, namely, a zinc ion (Zn2+ ) doped graphite carbon nitride (CN) system (BZCN), achieved through two high-temperature burning processes. By subjecting composite materials to microwave irradiation, an impressive 99.81% eradication of Staphylococcus aureus is observed within 15 min. Moreover, this treatment enhances the growth of bone marrow stromal cells. The Zn2+ doping effectively alters the electronic structure of CN, resulting in the generation of a substantial number of free electrons on the material's surface. Under microwave stimulation, sodium ions collide and ionize with the free electrons generated by BZCN, generating a large amount of energy, which reacts with water and oxygen, producing reactive oxygen species. In addition, Zn2+ doping improves the conductivity of CN and increases the number of unsaturated electrons. Under microwave irradiation, polar molecules undergo movement and generate frictional heat. Finally, the released Zn2+ promotes macrophages to polarize toward the M2 phenotype, which is beneficial for tibial repair.

Engineering Dynamic Defect of CeIII /CeIV -Based Metal-Organic Framework through Ultrasound-Triggered Au Electron Trapper for Sonodynamic Therapy of Osteomyelitis.

Defect engineering is an important way to tune the catalytic properties of metal-organic framework (MOF), yet precise control of defects is difficult to achieve. Herein, a cerium-based MOF (CeTCPP) is decorated with Au nanoparticles. Under ultrasound irradiation, Au nanoparticles can precisely turn 1/3 of the pristine Ce3+ nodes into Ce4+ . With the stable existence of Ce4+ , the coordination of Ce nodes changed, causing the structural irregularity in CeTCPP-Au, so that the electron-hole recombination is obviously hindered, facilitating the generation of reactive oxygen species. Therefore, under 20 min of ultrasound irradiation, the CeTCPP-Au showed superior antibacterial efficacy of over 99% against Staphylococcus aureus and Escherichia coli with good biocompatibility, which is further used for effective therapy of osteomyelitis. Overall, this work provides a dynamic defect formation strategy of MOF through the electron trapping of Au nanoparticles, which also sheds light on sonodynamic therapy in curing deep-seated lesions.

High-performance five-ring-fused organic semiconductors for field-effect transistors.

Organic molecular semiconductors have been paid great attention due to their advantages of low-temperature processability, low fabrication cost, good flexibility, and excellent electronic properties. As a typical example of five-ring-fused organic semiconductors, a single crystal of pentacene shows a high mobility of up to 40 cm2 V-1 s-1, indicating its potential application in organic electronics. However, the photo- and optical instabilities of pentacene make it unsuitable for commercial applications. But, molecular engineering, for both the five-ring-fused building block and side chains, has been performed to improve the stability of materials as well as maintain high mobility. Here, several groups (thiophenes, pyrroles, furans, etc.) are introduced to design and replace one or more benzene rings of pentacene and construct novel five-ring-fused organic semiconductors. In this review article, ∼500 five-ring-fused organic prototype molecules and their derivatives are summarized to provide a general understanding of this catalogue material for application in organic field-effect transistors. The results indicate that many five-ring-fused organic semiconductors can achieve high mobilities of more than 1 cm2 V-1 s-1, and a hole mobility of up to 18.9 cm2 V-1 s-1 can be obtained, while an electron mobility of 27.8 cm2 V-1 s-1 can be achieved in five-ring-fused organic semiconductors. The HOMO-LUMO levels, the synthesis process, the molecular packing, and the side-chain engineering of five-ring-fused organic semiconductors are analyzed. The current problems, conclusions, and perspectives are also provided.

Alloying-Triggered Phase Engineering of NiFe System via Laser-Assisted Al Incorporation for Full Water Splitting.

It is challenging to design one non-noble material with balanced bifunctional performance for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) for commercial sustainability at a low cost since the different electrocatalytic mechanisms are not easily matchable for each other. Herein, a self-standing hybrid system Ni18 Fe12 Al70 , consisting of Ni2 Al3 and Ni3 Fe phases, was constructed by laser-assisted aluminum (Al) incorporation towards full water splitting. It was found that the incorporation of Al could effectively tune the morphologies, compositions and phases. The results indicate that Ni18 Fe12 Al70 delivers an extremely low overpotential to trigger both HER (η100 =188 mV) and OER (η100 =345 mV) processes and maintains a stable overpotential for 100 h, comparable to state-of-the-art electrocatalysts. The synergistic effect of Ni2 Al3 and Ni3 Fe alloys on the HER process is confirmed based on theoretical calculation.

Oxygen Vacancies-Rich Heterojunction of Ti3 C2 /BiOBr for Photo-Excited Antibacterial Textiles.

Pathogenic bacteria that adhere on the surface of textiles, especially healthcare workers' uniforms, have brought severe problems, including nosocomial infection and other infectious diseases. Here, antibacterial textiles are fabricated by in situ growing oxygen vacancies (OVs) BiOBr on the surface of Ti3 C2 nanosheets followed by in situ polymerization of polypyrrole (ppy). The formed Schottky heterojunction containing OVs of Ti3 C2 /BiOBr effectively enhance the transfer and separation of photogenerated carriers, inhibit the recombination, and decrease the band gap by introducing defect level, which significantly improve the photocatalytic activity, leading to higher reactive oxygen species (ROS) under light irradiation. Therefore, the antibacterial efficacy of textiles reaches up to 98.64% against Staphylococcus aureus and 99.89% against Escherichia coli with the assistance of hyperthermia under light irradiation for 15 min. This work provides insights for designing photo-excited antibacterial textiles by interfacial construction based on Schottky junctions and OVs in the incorporated nanomaterials.

Magnetic Composite Rapidly Treats Staphylococcus aureus-Infected Osteomyelitis through Microwave Strengthened Thermal Effects and Reactive Oxygen Species.

It is difficult to effectively treat bacterial osteomyelitis using photothermal therapy or photodynamic therapy due to poor penetration of light. Here, a microwave (MW)-excited magnetic composite of molybdenum disulfide (MoS2 ) / iron oxide (Fe3 O4 ) is reported for the treatment of bacteria-infected osteomyelitis. In in vitro and in vivo experiments, MoS2 /Fe3 O4 is shown to effectively eradicate bacteria-infected mouse tibia osteomyelitis, due to MW thermal enhancement and reactive oxygen species (ROS) (1 O2 and ·O2 - ) production under MW radiation. In addition, the mechanism of MW heat generation is proposed by MW network vector analysis. By the density functional theory and finite element method, the ROS generation mechanism is proposed. The synergy or conductive network between dielectric MoS2 and magnetic Fe3 O4 can reach both enhancement of the dielectric and magnetic attenuation capability. In addition, abundant interfaces are generated to enhance the attenuation of electromagnetic waves by MoS2 and Fe3 O4, introducing multiple reflections and interfacial polarization. Therefore, MoS2 /Fe3 O4 has excellent MW absorption ability based on the synergy or conductive network between MoS2 and magnetic Fe3 O4 as well as multiple dielectric reflections and interfacial polarization.

The recent progress on metal-organic frameworks for phototherapy.

Some infectious or malignant diseases such as cancers are seriously threatening the health of human beings all over the world. The commonly used antibiotic therapy cannot effectively treat these diseases within a short time, and also bring about adverse effects such as drug resistance and immune system damage during long-term systemic treatment. Phototherapy is an emerging antibiotic-free strategy to treat these diseases. Upon light irradiation, phototherapeutic agents can generate cytotoxic reactive oxygen species (ROS) or induce a temperature increase, which leads to the death of targeted cells. These two kinds of killing strategies are referred to as photodynamic therapy (PDT) and photothermal therapy (PTT), respectively. So far, many photo-responsive agents have been developed. Among them, the metal-organic framework (MOF) is becoming one of the most promising photo-responsive materials because its structure and chemical compositions can be easily modulated to achieve specific functions. MOFs can have intrinsic photodynamic or photothermal ability under the rational design of MOF construction, or serve as the carrier of therapeutic agents, owing to its tunable porosity. MOFs also provide feasibility for various combined therapies and targeting methods, which improves the efficiency of phototherapy. In this review, we firstly investigated the principles of phototherapy, and comprehensively summarized recent advances of MOF in PDT, PTT and synergistic therapy, from construction to modification. We expect that our demonstration will shed light on the future development of this field, and bring it one step closer to clinical trials.

ALD-induced TiO2/Ag nanofilm for rapid surface photodynamic ion sterilization.

The daily life of people in the intelligent age is inseparable from electronic device, and a number of bacteria on touch screens are increasingly threatening the health of users. Herein, a photocatalytic TiO2/Ag thin film was synthesized on a glass by atomic layer deposition and subsequent in situ reduction. Ultraviolet-visible (UV-Vis) spectra showed that this film can harvest the simulated solar light more efficiently than that of pristine TiO2. The antibacterial tests in vitro showed that the antibacterial efficiency of the TiO2/Ag film against S. aureus and E. coli was 98.2% and 98.6%, under visible light irradiation for 5 min. The underlying mechanism was that the in-situ reduction of Ag on the surface of TiO2 reduced the bandgap of TiO2 from 3.44 to 2.61 eV due to the formation of Schottky heterojunction at the interface between TiO2 and Ag. Thus, TiO2/Ag can generate more reactive oxygen species for bacterial inactivation on the surface of electronic screens. More importantly, the TiO2/Ag film had great biocompatibility with/without light irradiation. The platform not only provides a more convenient choice for the traditional antibacterial mode but also has limitless possibilities for application in the field of billions of touch screens.

2D MOF Periodontitis Photodynamic Ion Therapy.

Traditional surgical intervention and antibiotic treatment are poor and even invalid for chronic diseases including periodontitis induced by diverse oral pathogens, which often causes progressive destruction of tissues, even tooth loss, and systemic diseases. Herein, an ointment comprising atomic-layer Fe2O3-modified two-dimensional porphyrinic metal-organic framework (2D MOF) nanosheets is designed by incorporating a polyethylene glycol matrix. After the atomic layer deposition surface engineering, the enhanced photocatalytic activity of the 2D MOF heterointerface results from lower adsorption energy and more charge transfer amounts due to the synergistic effect of metal-linker bridging units, abundant active sites, and an excellent light-harvesting network. This biocompatible and biodegradable 2D MOF-based heterostructure exhibits broad-spectrum antimicrobial activity (99.87 ± 0.09%, 99.57 ± 0.21%, and 99.03 ± 0.24%) against diverse oral pathogens (Porphyromonas gingivalis, Fusobacterium nucleatum, and Staphylococcus aureus) by the synergistic effect of reactive oxygen species and released ions. This photodynamic ion therapy exhibits a superior therapeutic effect to the reported clinical periodontitis treatment owing to rapid antibacterial activity, alleviative inflammation, and improved angiogenesis.

ZIF-67 derived Co@NC/g-C3N4 as a photocatalyst for enhanced water splitting H2 evolution.

Graphitic carbon nitride (g-C3N4), as the one of the most promising photocatalysts, usually relies on noble metal co-catalysts in the photocatalytic water splitting H2 evolution process, which greatly increases the use cost. Here, a zeolite imidazole framework (ZIF-67) derived Co@NC/g-C3N4 composite was constructed through facile thermal condensation of ZIF-67 and melamine. The obtained Co@NC/g-C3N4 composites can drive water splitting H2 evolution without any noble metal co-catalyst under simulated sunlight. The optimal sample exhibits the highest H2 evolution rate of 161 µmol g-1·h-1, which is 6 times of pure g-C3N4. The N doped carbon in carbonized ZIF-67 can not only quickly capture separated electrons from g-C3N4, but also serve as the co-catalyst. The well dispersed cobalt intermediate on carbonized ZIF-67 also play a role in promoting electron conversion. The formation of junction between carbonized ZIF-67 and g-C3N4 could promote quick charge carrier separation and transfer. This work provides a new idea for photocatalytic H2 evolution without noble metal co-catalysis.

Novel Bionic Topography with MiR-21 Coating for Improving Bone-Implant Integration through Regulating Cell Adhesion and Angiogenesis.

Implant loosening is still the major form of the failure of artificial joints. Herein, inspired by the operculum of the river snail, we prepared a novel bionic micro/nanoscale topography on a titanium surface. This bionic topography promoted early cell adhesion through up-regulating the expression of ITG α5ß1 and thus accelerated the following cell spreading, proliferation, and differentiation. Moreover, a miR-21 coating, which promoted the angiogenic differentiation of MSCs, was fabricated on the bionic topography. Benefiting from both bionic micro/nanoscale topography and miR-21, blood vessel growth and bone formation and mineralization around the implant, as well as bone-implant bonding strength, were significantly improved. Collectively, the present study highlights the combination of the bionic micro/nanoscale topography and miR-21 on promoting cell adhesion and angiogenic differentiation and improving in vivo angiogenesis and bone-implant osseointegration. This work provides a new train of thought propelling the development of implants for potential application in the orthopedics field.

Rapid and Superior Bacteria Killing of Carbon Quantum Dots/ZnO Decorated Injectable Folic Acid-Conjugated PDA Hydrogel through Dual-Light Triggered ROS and Membrane Permeability.

One of the most difficult challenges in the biomedical field is bacterial infection, which causes tremendous harm to human health. In this work, an injectable hydrogel is synthesized through rapid assembly of dopamine (DA) and folic acid (FA) cross-linked by transition metal ions (TMIs, i.e., Zn2+ ), which was named as DFT-hydrogel. Both the two carboxyl groups in the FA molecule and catechol in polydopamine (PDA) easily chelates Zn2+ to form metal-ligand coordination, thereby allowing this injectable hydrogel to match the shapes of wounds. In addition, PDA in the hydrogel coated around carbon quantum dot-decorated ZnO (C/ZnO) nanoparticles (NPs) to rapidly generate reactive oxygen species (ROS) and heat under illumination with 660 and 808 nm light, endows this hybrid hydrogel with great antibacterial efficacy against Staphylococcus aureus (S. aureus, typical Gram-positive bacteria) and Escherichia coli (E. coli, typical Gram-negative bacteria). The antibacterial efficacy of the prepared DFT-C/ZnO-hydrogel against S. aureus and E. coli under dual-light irradiation is 99.9%. Importantly, the hydrogels release zinc ions over 12 days, resulting in a sustained antimicrobial effect and promoted fibroblast growth. Thus, this hybrid hydrogel exhibits great potential for the reconstruction of bacteria-infected tissues, especially exposed wounds.

Electrophoretic Deposited Stable Chitosan@MoS2 Coating with Rapid In Situ Bacteria-Killing Ability under Dual-Light Irradiation.

Developing in situ disinfection methods in vivo to avoid drug-resistant bacteria and tissue toxicity is an urgent need. Here, the photodynamic and photothermal properties of the chitosan-assisted MoS2 (CS@MoS2 ) hybrid coating are simultaneously inspired to endow metallic Ti implants with excellent surface self-antibacterial capabilities. This coating, irradiated by only 660 nm visible light (VL) for 10 min, exhibits an antibacterial efficacy of 91.58% and 92.52% against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), respectively. The corresponding value is 64.67% and 57.44%, respectively, after irradiation by a single 808 nm near infrared light for the same amount of time. However, the combined irradiation using both lights can significantly enhance the efficiency up to 99.84% and 99.65% against E. coli and S. aureus, respectively, which can be ascribed to the synergistic effects of photodynamic and photothermal actions. The former produces single oxygen species under 660 nm VL while the latter induces a rise in temperature of implants, which can inhibit the growth of both E. coli and S. aureus. The introduction of CS can also promote the biocompatibility of implants, which provides a facile, rapid, and safe in situ bacteria-killing method in vivo without needing a second surgery.

In Situ Disinfection through Photoinspired Radical Oxygen Species Storage and Thermal-Triggered Release from Black Phosphorous with Strengthened Chemical Stability.

Photodynamic therapy (PDT) utilizing light-induced reactive oxygen species (ROS) is a promising alternative to combat antibiotic-resistant bacteria and biofilm. However, the photosensitizer (PS)-modified surface only exhibits antibacterial properties in the presence of light. It is known that extended photoirradiation may lead to phototoxicity and tissue hypoxia, which greatly limits PDT efficiency, while ambient pathogens also have the opportunity to attach to biorelevant surfaces in medical facilities without light. Here, an antimicrobial film composed of black phosphorus nanosheets (BPSs) and poly (4-pyridonemethylstyrene) endoperoxide (PPMS-EPO) to control the storage and release of ROS reversibly is introduced. BPS, as a biocompatible PS, can produce high singlet oxygen under the irradiation of visible light of 660 nm, which can be stably stored in PPMS-EPO. The ROS can be gradually thermally released in the dark. In vitro antibacterial studies demonstrate that the PPMS-EPO/BPS film exhibits a rapid disinfection ability with antibacterial rate of 99.3% against Escherichia coli and 99.2% against Staphylococcus aureus after 10 min of irradiation. Even without light, the corresponding antibacterial rate reaches 76.5% and 69.7%, respectively. In addition, incorporating PPMS significantly improves the chemical stability of the BPS.

Poloxamer 407 modified collagen/ß-tricalcium phosphate scaffold for localized delivery of alendronate.

Systemic administration of alendronate is associated with various adverse reactions in clinical settings. To mitigate these side effects, poloxamer 407 (P-407) modified with cellulose was chosen to encapsulate alendronate. This drug-loaded system was then incorporated into a collagen/ß-tricalcium phosphate (ß-TCP) scaffold to create a localized drug delivery system. Nuclear magnetic resonance spectrum and rheological studies revealed hydrogen bonding between P-407 and cellulose as well as a competitive interaction with water that contributed to the delayed release of alendronate (ALN). Analysis of the degradation kinetics of P-407 and release kinetics of ALN indicated zero-order kinetics for the former and Fickian or quasi-Fickian diffusion for the latter. The addition of cellulose, particularly carboxymethyl cellulose (CMC), inhibited the degradation of P-407 and prolonged the release of ALN. The scaffold's structure increased the contact area of P-407 with the PBS buffer, thereby, influencing the release rate of ALN. Finally, biocompatibility testing demonstrated that the drug delivery system exhibited favorable cytocompatibility and hemocompatibility. Collectively, these findings suggest that the drug delivery system holds promise for implantation and bone healing applications.