Shear Flow-Assembled Janus Membrane with Bifunctional Osteogenic and Antibacterial Effects for Guided Bone Regeneration.

Guided bone regeneration (GBR) membranes that reside at the interface between the bone and soft tissues for bone repair attract increasing attention, but currently developed GBR membranes suffer from relatively poor osteogenic and antibacterial effects as well as limited mechanical property and biodegradability. We present here the design and fabrication of a bifunctional Janus GBR membrane based on a shear flow-driven layer by a layer self-assembly approach. The Janus GBR membrane comprises a calcium phosphate-collagen/polyethylene glycol (CaP@COL/PEG) layer and a chitosan/poly(acrylic acid) (CHI/PAA) layer on different sides of a collagen membrane to form a sandwich structure. The membrane exhibits good mechanical stability and tailored biodegradability. It is found that the CaP@COL/PEG layer and CHI/PAA layer contribute to the osteogenic differentiation and antibacterial function, respectively. In comparison with the control group, the Janus GBR membrane displays a 2.52-time and 1.84-time enhancement in respective volume and density of newly generated bone. The greatly improved bone repair ability of the Janus GBR membrane is further confirmed through histological analysis, and it has great potential for practical applications in bone tissue engineering.

Integrating photothermal and plasmonic catalysis induced by near-infrared light for efficient reduction of 4-nitrophenol.

The reduction of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) is an important reaction in both chemical manufacturing and environmental protection. The design of a highly active, multifunctional and reusable catalyst for efficient 4-NP decontamination/valorization is therefore crucial to bring in economic and societal benefits. Herein, we achieve an efficient plasmonic-photothermal catalyst of Pd nanoparticles by growing them on graphene-polyelectrolytes self-assembly nanolayers via an in situ green reduction approach using polyelectrolyte as the reductant. The as-fabricated catalyst shows high catalytic behaviors and good stability (maintained over 92.5 % conversion efficiency after ten successive cycles) for 4-NP reduction under ultra-low catalyst dose. The rate constant and turnover frequency were calculated at 0.197 min-1 and 7.79 mmol g-1 min-1, respectively, which were much higher than those of most reported catalysts. Moreover, the as-prepared catalyst exhibited excellent photothermal conversion efficiency of ∼77 % and boosted 4-NP reduction by ∼2-fold under near-infrared irradiation (NIR). This study provides valuable insights into the design of greener catalytic materials and facilitates the development of multifunctional plasmonic-photothermal catalysts for diverse environmental, chemical, and energy applications using NIR.

Promoting Piezocatalytic H2 O2 Production in Pure Water by Loading Metal-Organic Cage-Modified Gold Nanoparticles on Graphitic Carbon Nitride.

Piezocatalytic hydrogen peroxide (H2 O2 ) production is a green synthesis method, but the rapid complexation of charge carriers in piezocatalysts and the difficulty of adsorbing substrates limit its performance. Here, metal-organic cage-coated gold nanoparticles are anchored on graphitic carbon nitride (MOC-AuNP/g-C3 N4 ) via hydrogen bond to serve as the multifunctional sites for efficient H2 O2 production. Experiments and theoretical calculations prove that MOC-AuNP/g-C3 N4 simultaneously optimize three key parts of piezocatalytic H2 O2 production: i) the MOC component enhances substrate (O2 ) and product (H2 O2 ) adsorption via host-guest interaction and hinders the rapid decomposition of H2 O2 on MOC-AuNP/g-C3 N4 , ii) the AuNP component affords a strong interfacial electric field that significantly promotes the migration of electrons from g-C3 N4 for O2 reduction reaction (ORR), iii) holes are used for H2 O oxidation reaction (WOR) to produce O2 and H+ to further promote ORR. Thus, MOC-AuNP/g-C3 N4 can be used as an efficient piezocatalyst to generate H2 O2 at rates up to 120.21 µmol g-1 h-1 in air and pure water without using sacrificial agents. This work proposes a new strategy for efficient piezocatalytic H2 O2 synthesis by constructing multiple active sites in semiconductor catalysts via hydrogen bonding, by enhancing substrate adsorption, rapid separation of electron-hole pairs and preventing rapid decomposition of H2 O2 .

Controlled release of herbicides through glyphosate intercalated layered double hydroxides and enhancement of anti-scouring ability via poly-l-aspartic acid and chitosan modification.

Nanocarrier preparations could effectively improve the utilization rate of pesticides, and reduce pesticide loss. In this study, glyphosate (GLY)-loaded MgAl layered double hydroxide (GLY@LDH) was synthesized via an in-situ method. Subsequently, GLY@LDH composite samples were prepared using a layer-by-layer self-assembly approach and modified with poly-L-aspartic acid (PASP) and chitosan (CS). XRD, FT-IR, SEM, and Zeta potential characterization confirmed that GLY was successfully loaded in the interlayer of LDHs and PASP/CS were successfully encapsulated on the surface of the composite sample. The release effect in different ionic solutions and soils was studied and analyzed. The release behavior conforms to the Ritger-Peppas kinetic model, and the release mechanism was ion exchange, which was further explored by means of XRD, SEM, and molecular simulation. The results of the anti-scouring experiment and contact angle measurement indicated that the layered self-assembly material enhanced the washing resistance of the material. The practical application effect of the sample was verified through a pot experiment. This study provides new insights into the simple preparation of pesticide-controlled release formulations that reduce leaching losses.

Biomineralized Piezoelectrically Active Scaffolds for Inducing Osteogenic Differentiation.

There is an endogenous electric field in living organisms, which plays a vital role in the development and regeneration of bone tissue. Therefore, self-powered piezoelectric material for bone repair has become hot research in recent years. However, the current piezoelectric materials for tissue regeneration still have the shortcomings of lack of biological activity and three-dimensional structure. Here, we proposed a three-dimensional polyurethane foam (PUF) scaffold coated with piezoelectric poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and modified by a calcium phosphate (CaP) mineralized coating. The preferred scaffold has an open circuit voltage and short circuit current output of 5 V and 200 nA. Combining the physical and chemical properties of the CaP coating, the piezoelectric signal of PVDF-HFP and the three-dimensional structure of PUF, the scaffold exhibits superior promotion of cell osteogenic differentiation and ectopic bone formation in vivo. The mechanism is attributed to an increase in intracellular Ca2+ levels in response to chemical and piezoelectric stimulation with the material. This research not only paves the way for the application of piezoelectric scaffolds to stimulate osteoblasts differentiation in situ, but also lays the foundation for the clinical treatment of long-term osteoporosis.

Bioactive NAD+ Regeneration Promoted by Multimetallic Nanoparticles Based on Graphene-Polymer Nanolayers.

The concentration of nicotinamide adenine dinucleotide oxidized form (NAD+) changes during aging, and the production of NAD+ can significantly affect both health span and life span. However, it is still of great challenge to regenerate NAD+ from its precursors. Herein, we introduce a method to prepare multimetallic nanoparticles (including Au, Pt, Cu, and MgO) that can efficiently promote the conversion of NADH to NAD+. The nanoparticles are made by mixing reduced graphene oxide-polyethyleneimine-polyacrylic acid nano-films with metallic salts, where four different metal ions are reduced and grow at the surface of the nanolayers. The morphology, size, and growth rate of nanoparticles can be controlled by adding surfactants, applying an electric field, and so forth. Our multimetallic nanoparticles exhibit excellent catalytic performance that a complete conversion of NADH to NAD+ can be finished in 3 min without introducing additional oxygen. This work presents a way for the preparation of multimetallic nanoparticles to promote NAD+ regeneration, which shows great promise for the future design of high-performance materials for antiaging.

A healing promoting wound dressing with tailor-made antibacterial potency employing piezocatalytic processes in multi-functional nanocomposites.

Developing a novel antibiotics-free antibacterial strategy is essential for minimizing bacterial resistance. Materials that not only kill bacteria but also promote tissue healing are especially challenging to achieve. Inspired by chemical conversion processes in living organisms, we develop a piezoelectrically active antibacterial device that converts ambient O2 and H2O to ROS by piezocatalytic processes. The device is achieved by mounting nanoscopic polypyrrole/carbon nanotube catalyst multilayers onto piezoelectric-dielectric films. Under stimuli by a hand-held massage device, the sterilizing rates for S. aureus and E. coli reach 84.11% and 94.85% after 10 minutes of operation, respectively. The antibacterial substrate at the same time preserves and releases drugs and presents negligible cytotoxicity. Animal experiments demonstrate that daily treatment for 10 minutes using the device effectively accelerates the healing of infected wounds on the backs of mice, promoting hair follicle generation and collagen deposition. We believe that this report provides a novel design approach for antibacterial strategies in medical treatment.

Biofriendly molecular and protein release substrate with integrated piezoelectric motivation and anti-oxidative stress capabilities.

Self-powered piezoelectrically active molecular or protein delivery devices have provoked great interest in recent years. However, electric fields used to promote delivery or healing may also induce the redox of water or oxygen to generate reactive oxygen species (ROS) and bring unintended oxidative pressure to the organism and harm biological functions. In addition, protein molecules are easily inactivated in the polymer reservoir matrix due to the pull of strong electrostatic effects. In this study, a multifunctional molecular delivery substrate was fabricated by integrating a piezoelectric-dielectric polymeric substrate, nanoscopic polyelectrolyte films and in-film deposited biomimetic porous CaP coating. The piezoelectric substrate promoted molecular release, and the mineralized coating effectively stored molecules or proteins and simultaneously eliminated ROS, reducing the oxidative stress response generated by oxidative pressure. The present work opens a new way for the development of multifunctional and biofriendly drug delivery devices.

Multifunctional agents based on benzoxazolone as promising therapeutic drugs for diabetic nephropathy.

Diabetic nephropathy (DN) is resulted from activations of polyol pathway and oxidative stress by abnormal metabolism of glucose, and no specific medication is available. We designed a novel class of benzoxazolone derivatives, and a number of individuals were found to have significant antioxidant activity and inhibition of aldose reductase of the key enzyme in the polyol pathway. The outstanding compound (E)-2-(7-(4-hydroxy-3-methoxystyryl)-2-oxobenzo[d]oxazol-3(2H)-yl)acetic acid was identified to reduce urinary proteins in diabetic mice suggesting an alleviation in the diabetic nephropathy, and this was confirmed by kidney hematoxylin-eosin staining. Further investigations showed blood glucose normalization, declined in the polyol pathway and lipid peroxides, and raised glutathione and superoxide dismutase activity. Thus, we suggest a therapeutic function of the compound for DN which could be attributed to the combination of hypoglycemic, aldose reductase inhibition and antioxidant.

Synthesis, characterization, and photoelectric properties of iridium(iii) complexes containing an N hetero-dibenzofuran C

In this study, three high-efficient green light iridium(iii) complexes were designed and synthesized, wherein 2-methyl-8-(2-pyridine) benzofuran [2,3-B] pyridine (MPBFP) is the main ligand and three ß-diketone derivatives, namely 3,7-diethyl-4,6-nondiazone (detd), 2,2,6,6-tetramethyl-3,5-heptyldione (tmd) and acetylacetone (acac), are ancillary ligands. The thermal stabilities, electrochemical properties, and electroluminescence (EL) performance of these three complexes, namely (MPBFP)2 Ir(detd), (MPBFP)2Ir(tmd) and (MPBFP)2Ir(acac), were investigated. The results show that the absorption peaks of the three complexes range from 260 to 340 nm, and the maximum emission wavelengths are 537 nm, 544 nm and 540 nm, respectively. The LUMO level is -2.18 eV, -2.20 eV, -2.21 eV, and the HOMO level is -5.30 eV, -5.25 eV, and -5.25 eV, respectively. The thermal decomposition temperatures of each of the three compounds are 359 °C, 389 °C and 410 °C respectively, with a weight loss of 5%. Green phosphorescent electroluminescent devices were prepared with the structure of ITO/HAT-CN/TAPC/TCTA/TCTA:X/Bepp2/LiF/Al, and the three complexes were dispersed in the organic light-emitting layer as the guest material X. The maximum external quantum efficiency of the devices is 17.2%, 16.7%, and 16.5%, respectively. The maximum brightness is 57 328 cd m-2, 69 267 cd m-2 and 69 267 cd m-2, respectively. With respect to the EL properties, (MPBFP)2Ir(detd) is the best performer among the three complexes. The different performances exhibited by these complexes were discussed from the view point of substituent effect on the ß-diketone ligands.

A layer-by-layer strategy for the scalable preparation of uniform interfacial electrocatalysts with high structural tunability: a case study of a CoNP/N,P-graphene catalyst complex.

Electrocatalysts are important for providing clean energy and have attracted intense research attention. All electrocatalysts must function on electrode surfaces; however, interfacial engineering strategies for electrocatalytic structures remain understudied, and scalable preparation methods are especially rare. In this study, we propose a strategy that employs a layer-by-layer (LbL) assembly, subsequent in-film deposition, and calcination to prepare a complex Co nanoparticle (CoNP)/N,P-graphene catalyst on various 2D and 3D electrode surfaces. We delicately adjusted a variety of parameters and demonstrated that our LbL-based method can finely tune the total amount, the doping fraction, and the electronic structure of the complex catalysts, and provide optimal catalytic performance. When prepared on a large piece of carbon cloth, the catalysts showed a highly uniform catalytic performance, demonstrating the capability of our method for scalable fabrication. Our study emphasizes the delicate nature of the interfacial engineering of electrocatalysts, and promotes functional interface design and mechanism studies.

Using a Graphene-Polyelectrolyte Complex Reducing Agent To Promote Cracking in Single-Crystalline Gold Nanoplates.

It is a challenge to produce single-crystalline gold nanoparticles having regular size definition designed for controlled light absorbance and internal structural inhomogeneities to enhance electro-magnetic fields. Here, we report a synthetic strategy to generate large single-crystalline triangular or hexagonal gold nanoplates with multiple cracks within the plates using a graphene-polyelectrolyte complex as both a surface adsorbent and bulk reducing agent. Large-scale gold nanoplates can be synthesized within 48 h. First-principles calculations indicate that the nanoplates have a kinetically limited morphology resulting from prior growth of {111} facets confined by the graphene-polyelectrolyte multilayer. The nanocracks result from the inability of the bulk reducing agent to enter narrow defect spaces during growth that remained permanently. The nanoplates had extraordinary physical-chemical detection sensitivity when used for surface-enhanced Raman scattering (SERS) and surface-enhanced infrared absorption (SEIRA). The limit of rhodamine 6G (Rh6G) SERS detection is as low as 5 × 10-13 M. The gold nanoplates also showed a remarkable light-to-heat conversion efficiency (68.5%). The approach described may be applicable to other metals so that tunable nanostructures can be generated by the graphene-polyelectrolyte multilayer strategy.

An Effective Osteogenesis Porous CaP/Collagen Interface Compatible with Various Substrates Fabricated by Controlled Mineralization in a Delicately Adjustable Organic Matrix.

Increasing bone formation on the surfaces of implants such as screws, plates, or shims holds great significance for clinical medicine. However, osteogenesis implant coatings that mimic natural bone in terms of both their components and structural features are still lacking. Here we report the biomimetic interface of calcium phosphate (CaP) in a collagen matrix fabricated by controlled mineralization that presents biomimetic porous features. The porous CaP/collagen interface, with a thickness of about 1 µm, significantly enhances osteogenesis, as verified at both the gene and protein levels as well as by in vivo experiments. Taking advantage of the generality of the method, the biomimetic interface was prepared on a variety of substrates, including conductive substrates, 3D metal meshes, plastic or elastic substrates, and even on filter papers. The adjustability and generality of the method have enabled new characterization tests to be developed during experiments on cells and thus should greatly facilitate clinical medicine and tissue engineering.

A self-powered delivery substrate boosts active enzyme delivery in response to human movements.

Stimulated drug releases in response to human movements are highly appealing in medical therapy and various daily uses. However, the design of a mechanically responsive substrate that presents high delivery capacities and can also preserve the activities of sensitive molecules such as enzymes is still challenging. Taking advantage of the recent development in effective piezoelectric flexible films and in molecular delivery devices, we propose a composite delivery substrate that preserves enzyme activities and enhances molecular delivery in response to human movements such as finger presses or massages. The substrate is achieved by combining two parts, which are the energy converting unit and the molecular loading and releasing unit. The energy converting unit is a piezoelectric-dielectric flexible composite film that produces enhanced electricity and preserves the electricity longer compared to a pure piezoelectric polymer. The molecular delivery unit is a layer-by-layer multilayer containing mesoporous silica particles that are assembled at pH 9 but used in neutral solutions. The releases of molecules including small molecules, peptides, and proteins are all accelerated in response to finger presses irrespective of the signs or densities of their charges. More importantly, the enzyme CAT preserves its activity after release from the composite substrates, meaning that the CAT-loaded (PAH/MS)n(PAH/DAS)n@rGO-TFB/PVDF-HFP composite substrate holds promise as a self-powered soothing pad that effectively removes residue H2O2.

Multiple-Enzyme Graphene Microparticle Presenting Adaptive Chemical Network Capabilities.

Interrelated reaction networks steered by multiple types of enzymes are among the most intriguing enzyme-based cellular features. These reaction networks display advanced features such as adaptation, stimuli-responsiveness, and decision-making in accordance with environmental cues. However, artificial enzyme particles are still deficient in network-level capabilities, mostly because delicate enzymes are difficult to immobilize and assemble. In this study, we propose a general strategy to prepare enzyme-based particles that demonstrate network reaction capability. We assembled multiple types of proteins with a nanoscopic binder prepared from polyelectrolyte and graphene. After assembly, the enzymes all preserved their catalytic capabilities. By incorporating multiple types of enzymes, the particles additionally displayed network-reaction capabilities. We were able to use NIR irradiations to quasi-reversibly adjust the catalytic abilities of these enzyme-based particles. In addition, after a biomimetic mineralization process was used to wrap the protein complexes in a MOF shell, the particles were more robust and catalytically active even after being immersed in acidic (pH 4) or basic (pH 10) solutions for 3 days. This study provides an insight into the study of network properties of functional enzyme particles experimentally and enriches scientific understanding of multifunctional or stimuli-responsive behaviors at the reaction network level. The building of artificial reaction networks possesses high potential in realizing intelligent microparticles that can perform complicated tasks.

A New Way to Promote Molecular Drug Release during Medical Treatment: A Polyelectrolyte Matrix on a Piezoelectric-Dielectric Energy Conversion Substrate.

Enhanced drug releases in a timely manner during urgent medical treatments would significantly enhance the prognosis of patients. Inspired by the facilitated molecular transports by the potentials, an enhanced drug release strategy driven by mechanical disturbances that widely exist in medical treatment processes is proposed. This strategy is enabled by a functional material comprised of multilayers of dendrimers as the drug reservoir, which are built on a piezoelectric-dielectric flexible film with reduced graphene oxide fillers. The generated voltages are higher and last longer than that in regular piezoelectric films. Photochemical crosslinking leads to a stable drug matrix which is even sustained in electric fields and high ionic strengths. The device enhances releases of positively, negatively, and zwitterionically charged molecules in response to mechanical stimuli and supports high cell viabilities. An illustrative application is demonstrated by preparing the material on the surface of a gastric lavage tube. The results show that the release of antiemetic drug increased by 200% within 60 min in response to forces mimicking human swallowing. This study contributes an integrative material that can realize electrically triggered releases that are previously only realized using complicated electrochemical setups. It is believed that this material can facilitate medicine applications in various emergent situations.

The Fabrication of rGO/(PLL/PASP)3 @DOX Nanorods with pH-Switch for Photothermal Therapy and Chemotherapy.

The development of well-controlled drug carriers that are stable and highly effective for the delivery of anticancer agents is challenging. Herein, we report a novel pH-controlled drug delivery system, utilizing reducing graphene oxide (rGO)-polymer self-assembly films as carriers, for the preparation of effective drug nanorods and nanoparticles. In this system, the rGO-polymer carriers were constructed by the alternating assembly of poly-l-lysine (PLL) and polyaspartic acid (PASP) around the rGO sheets. Furthermore, the rGO-polymer cores, which possess a positively charged surface as the desired template, could assemble with negatively charged doxorubicin (DOX) via electrostatic interactions. The DOX embedding efficiency and the morphology of the drug nanocomposites could be controlled by the number of rGO-polymer bilayers and concentration of the rGO-polymer bilayers and the initial DOX concentration. Importantly, the release of DOX could be regulated by controlling the pH and by using a NIR laser. Under acidic conditions, the interactions between the PASP layer and DOX molecules can be broken, resulting in gradual release of the DOX molecules. Upon NIR irradiation, the release of DOX could be further accelerated and a photothermal effect from rGO induced. Cellular uptake and cytotoxicity experiments indicate that the drug nanocomposites possess effective anticancer activity. Thus, in this work, we present a useful strategy for the fabrication of pH-responsive drug nanocomposites for combined photothermal and chemical therapy. The nanocomposite can be used as a potential drug delivery system for practical cancer treatment.

Dehydrothermally crosslinked collagen/hydroxyapatite composite for enhanced in vivo bone repair.

Bone repair accounts for a large number of surgical operations. However, artificial bone replacement materials do not present the delicate continuing adjustment ability like natural bones and cause obvious side effects. Thus, materials that induce the regeneration of bones would be an optimal choice to repair bone tissues. This study proposes a biocompatible bone repair material prepared from crosslinked porous composite of collagen and hydroxyapatite. The proposed dehydrothermal method to cross-link the composite avoids use of extra chemical reagents for crosslinking and ensures that the materials were prepared using only bio-compatible materials. By adjusting the preparative parameters such as componential ratios or heating period, materials with a large property space could be achieved. Properties including porosity, mechanical strength, and swelling ratios could be facilely adjusted, promising its applications in personalized medical treatment. Cell experiments and animal experiments demonstrate the material presented high biocompatibility and effectively induced osteanagenesis in vivo. We expect the proposed material possesses high commercialization potential and serves as an effective bone repair material in realistic applications.