Amnion-derived hydrogels as a versatile platform for regenerative therapy: from lab to market.

In recent years, the amnion (AM) has emerged as a versatile tool for stimulating tissue regeneration and has been of immense interest for clinical applications. AM is an abundant and cost-effective tissue source that does not face strict ethical issues for biomedical applications. The outstanding biological attributes of AM, including side-dependent angiogenesis, low immunogenicity, anti-inflammatory, anti-fibrotic, and antibacterial properties facilitate its usage for tissue engineering and regenerative medicine. However, the clinical usage of thin AM sheets is accompanied by some limitations, such as handling without folding or tearing and the necessity for sutures to keep the material over the wound, which requires additional considerations. Therefore, processing the decellularized AM (dAM) tissue into a temperature-sensitive hydrogel has expanded its processability and applicability as an injectable hydrogel for minimally invasive therapies and a source of bioink for the fabrication of biomimetic tissue constructs by recapitulating desired biochemical cues or pre-defined architectural design. This article reviews the multi-functionality of dAM hydrogels for various biomedical applications, including skin repair, heart treatment, cartilage regeneration, endometrium regeneration, vascular graft, dental pulp regeneration, and cell culture/carrier platform. Not only recent and cutting-edge research is reviewed but also available commercial products are introduced and their main features and shortcomings are elaborated. Besides the great potential of AM-derived hydrogels for regenerative therapy, intensive interdisciplinary studies are still required to modify their mechanical and biological properties in order to broaden their therapeutic benefits and biomedical applications. Employing additive manufacturing techniques (e.g., bioprinting), nanotechnology approaches (e.g., inclusion of various bioactive nanoparticles), and biochemical alterations (e.g., modification of dAM matrix with photo-sensitive molecules) are of particular interest. This review article aims to discuss the current function of dAM hydrogels for the repair of target tissues and identifies innovative methods for broadening their potential applications for nanomedicine and healthcare.

A sustainable and self-healable silk fibroin nanocomposite with antibacterial and drug eluting properties for 3D printed wound dressings.

The development of self-healable and 3D printable hydrogels with decent biocompatibility, mechanical durability, adhesiveness to tissues, and antibacterial activity is of great importance for wound healing applications. In this study, we present a sustainable and environmentally friendly composite hydrogel consisting of silk fibroin (SF), oxidized salep (OS), and kappa carrageenan nanoparticles (NPs) for efficient wound care. The injectable nanocomposite hydrogel is highly stretchable and exhibits strong tissue adhesiveness and self-healing response through Schiff-base cross-linking between OS and SF. The tunable shear-thinning viscoelastic properties of the hydrogel facilitate 3D bioprinting with excellent shape adaptability (97.7 ± 1.1% recovery), enabling the fabrication of complex-shaped constructs. In vitro release kinetics of tetracycline (TC) encapsulated in kappa carrageenan NPs indicate a distinctive Korsmeyer-Peppas profile, including an initial burst release followed by a triphasic pattern controlled by the embedded NPs within the hydrogel matrix. The composite hydrogel shows a remarkable broad-spectrum antibacterial activity with substantial zones of inhibition against S. aureus (34.00 ± 1.00 mm) and E. coli (27.60 ± 2.08 mm) after 24 h of incubation at 37 °C. The addition of TC further enhances the zones of inhibition by approximately 45% for S. aureus and 27% for E. coli. The control group without kappa NP incorporation shows no zone of inhibition, underscoring the critical role of the nanoparticles in imparting antibacterial activity to the hydrogel. Cytocompatibility assays show the high viability of fibroblast (L929) cells (>90%) in vitro. In vivo biocompatibility studies through subcutaneous implantation also do not show malignancy, infection, abscess, necrosis, epidermal or dermal modifications, or inflammation of the wounds after 14 days post-injection. H&E staining shows that the biodegradation of the developed hydrogel facilitates the growth of non-inflammatory cells, leading to the substitution of the injected hydrogel with autologous tissue. The detailed analyses affirm that the multifunctional injectable hydrogel with self-healing and antibacterial properties has high potential for wound healing and skin tissue engineering.

Advancements and applications of upconversion nanoparticles in wound dressings.

Wound healing is a complex process that requires effective management to prevent infections and promote efficient tissue regeneration. In recent years, upconversion nanoparticles (UCNPs) have emerged as promising materials for wound dressing applications due to their unique optical properties and potential therapeutic functionalities. These nanoparticles possess enhanced antibacterial properties when functionalized with antibacterial agents, helping to prevent infections, a common complication in wound healing. They can serve as carriers for controlled drug delivery, enabling targeted release of therapeutic agents to the wound site, allowing for tailored treatment and optimal healing conditions. These nanoparticles possess the ability to convert near-infrared (NIR) light into the visible and/or ultraviolet (UV) regions, making them suitable for therapeutic (photothermal therapy and photodynamic therapy) and diagnostic applications. In the context of wound healing, these nanoparticles can be combined with other materials such as hydrogels, fibers, metal-organic frameworks (MOFs), graphene oxide, etc., to enhance the healing process and prevent the growth of microbial infections. Notably, UCNPs can act as sensors for real-time monitoring of the wound healing progress, providing valuable feedback to healthcare professionals. Despite their potential, the use of UCNPs in wound dressing applications faces several challenges. Ensuring the stability and biocompatibility of UCNPs under physiological conditions is crucial for their effective integration into dressings. Comprehensive safety and efficacy evaluations are necessary to understand potential risks and optimize UCNP-based dressings. Scalability and cost-effectiveness of UCNP synthesis and manufacturing processes are important considerations for practical applications. In addition, efficient incorporation of UCNPs into dressings, achieving uniform distribution, poses an important challenge that needs to be addressed. Future research should prioritize addressing concerns regarding stability and biocompatibility, efficient integration into dressings, rigorous safety evaluation, scalability, and cost-effectiveness. The purpose of this review is to critically evaluate the advantages, challenges, and key properties of UCNPs in wound dressing applications to provide insights into their potential as innovative solutions for enhancing wound healing outcomes. We have provided a detailed description of various types of smart wound dressings, focusing on the synthesis and biomedical applications of UCNPs, specifically their utilization in different types of wound dressings.

Engineering Photo-Cross-Linkable MXene-Based Hydrogels: Durable Conductive Biomaterials for Electroactive Tissues and Interfaces.

Light-cured conductive hydrogels have attracted immense interest in the regeneration of electroactive tissues and bioelectronic interfaces. Despite the unique properties of MXene (MX), its light-blocking effect in the range of 300-600 nm hinders the efficient cross-linking of photocurable hydrogels. In this study, we investigated the photo-cross-linking process of MX-gelatin methacrylate (GelMa) composites with different types of photoinitiators and MX concentrations to prepare biocompatible, injectable, conductive, and photocurable composite hydrogels. The examined photoinitiators were Eosin Y, Irgacure 2959 (Type I), and lithium phenyl-2,4,6-trimethylbenzoyl phosphinate (Type II). The light-blocking effect of MX strongly affected the thickness, pore structure, swelling ratio, degradation, and mechanical properties of the light-cured hydrogels. Uniform distribution of MX in the hydrogel matrix was achieved at concentrations up to 0.04 wt % but the film thickness and curing times varied depending on the type of photoinitiator. It was feasible to prepare thin films (0.5 mm) by employing Type I photoinitiators under a relatively long light irradiation (4-5 min) while thick films with centimeter sizes could be rapidly cured by using Type II photoinitiator (<60 s). The mechanical properties, including elastic modulus, toughness, and stress to break for the Type II hydrogels were significantly superior (up to 300%) to those of Type I hydrogels depending on the MX concentration. The swelling ratio was also remarkably higher (648-1274%). A conductivity of about 1 mS/cm was attained at 0.1 mg/mL MX for the composite hydrogel cured by the Type I photoinitiator. In vitro cytocompatibility assays determined that the hydrogels promoted cell viability, metabolic activity, and robust proliferation of C2C12 myoblasts, which indicated their potential to support muscle cell growth during myogenesis. The developed photocurable GelMa-MX hydrogels have the potential to serve as bioactive and conductive scaffolds to modulate cellular functions and for tissue-device interfacing.

Plasma Processing and Treatment of 2D Transition Metal Dichalcogenides: Tuning Properties and Defect Engineering.

Two-dimensional transition metal dichalcogenides (TMDs) offer fascinating opportunities for fundamental nanoscale science and various technological applications. They are a promising platform for next generation optoelectronics and energy harvesting devices due to their exceptional characteristics at the nanoscale, such as tunable bandgap and strong light-matter interactions. The performance of TMD-based devices is mainly governed by the structure, composition, size, defects, and the state of their interfaces. Many properties of TMDs are influenced by the method of synthesis so numerous studies have focused on processing high-quality TMDs with controlled physicochemical properties. Plasma-based methods are cost-effective, well controllable, and scalable techniques that have recently attracted researchers' interest in the synthesis and modification of 2D TMDs. TMDs' reactivity toward plasma offers numerous opportunities to modify the surface of TMDs, including functionalization, defect engineering, doping, oxidation, phase engineering, etching, healing, morphological changes, and altering the surface energy. Here we comprehensively review all roles of plasma in the realm of TMDs. The fundamental science behind plasma processing and modification of TMDs and their applications in different fields are presented and discussed. Future perspectives and challenges are highlighted to demonstrate the prominence of TMDs and the importance of surface engineering in next-generation optoelectronic applications.

Electrochemical Wearable Biosensors and Bioelectronic Devices Based on Hydrogels: Mechanical Properties and Electrochemical Behavior.

Hydrogel-based wearable electrochemical biosensors (HWEBs) are emerging biomedical devices that have recently received immense interest. The exceptional properties of HWEBs include excellent biocompatibility with hydrophilic nature, high porosity, tailorable permeability, the capability of reliable and accurate detection of disease biomarkers, suitable device-human interface, facile adjustability, and stimuli responsive to the nanofiller materials. Although the biomimetic three-dimensional hydrogels can immobilize bioreceptors, such as enzymes and aptamers, without any loss in their activities. However, most HWEBs suffer from low mechanical strength and electrical conductivity. Many studies have been performed on emerging electroactive nanofillers, including biomacromolecules, carbon-based materials, and inorganic and organic nanomaterials, to tackle these issues. Non-conductive hydrogels and even conductive hydrogels may be modified by nanofillers, as well as redox species. All these modifications have led to the design and development of efficient nanocomposites as electrochemical biosensors. In this review, both conductive-based and non-conductive-based hydrogels derived from natural and synthetic polymers are systematically reviewed. The main synthesis methods and characterization techniques are addressed. The mechanical properties and electrochemical behavior of HWEBs are discussed in detail. Finally, the prospects and potential applications of HWEBs in biosensing, healthcare monitoring, and clinical diagnostics are highlighted.

Chitosan, polyethylene oxide/polycaprolactone electrospun core/shell nanofibrous mat containing rosuvastatin as a novel drug delivery system for enhancing human mesenchymal stem cell osteogenesis.

Introduction: Due to the potential positive effects of rosuvastatin (RSV) on human mesenchymal stem cells (MSCs) osteogenesis and new bone regeneration, it is crucial to develop a suitable carrier that can effectively control the release profile of RSV. The primary objective of this study was to introduce a novel drug delivery system based on core/shell nanofibrous structures, enabling a sustained release of RSV. Methods: To achieve this, coaxial electrospinning was employed to fabricate chitosan (CS)+polyethylene oxide (PEO)/polycaprolactone (PCL) nanofibrous mats, wherein RSV was incorporated within the core of nanofibers. By optimizing the relevant parameters of the electrospinning process, the mats' surface was further modified using plasma treatment. The fibers' shape, structure, and thermal stability were characterized. The wettability, and degradation properties of the fabricated mats were also examined. In vitro studies were conducted to examine the release behavior of RSV. Additionally, the capability of MSCs to survive and differentiate into osteocytes when cultured on nanofibers containing RSV was evaluated. Results: Results demonstrated the successful fabrication of CS + PEO + RSV/PCL core/shell mats with a core diameter of approximately 370 nm and a shell thickness of around 70 nm under optimized conditions. Plasma treatment was found to enhance the wettability and drug-release behavior of the mats. The nanofibrous structure, serving as a carrier for RSV, exhibited increased proliferation of MSCs and enhanced osteogenic differentiation. Conclusion: Therefore, it can be concluded that CS + PEO + RSV/PCL core/shell nanofibrous structure can be utilized as a sustained-release platform for RSV over an extended period, making it a promising candidate for guided bone regeneration.

Hybrid ultrasound-activated nanoparticles based on graphene quantum dots for cancer treatment.

Theranostic liposomes have recently found a broad range of applications in nanomedicine due to stability, the high solubility of biomacromolecules, bioavailability, efficacy, and low adverse effects. However, the limitations of liposomes concerning the short systemic circulation in the body, limited controllability of the release rate, and the inability of in vivo imaging remain challenging. Herein, the development of novel hybrid ultrasound-activated piezoelectric nanoparticles based on a hybrid liposome nanocarrier composed of poly(vinylidene fluoride-trifluoroethylene), graphene quantum dots (GQDs), and Silibinin (a hydrophobic drug) is presented. The hybrid nanoparticles are an acoustically sensitive drug delivery platform that releases the biomacromolecules in a specific tissue area (through surface labeling with PD-1 antibody) in a non-invasive and controlled manner. We show that the developed hybrid nanoparticles (with an average outer diameter of âˆ¼ 230 ± 20 nm) enable piezoelectric-stimulated drug delivery combined with simultaneous fluorescent imaging of cancer cells in vivo. Significant enhancement (>80 % up to 240 h) and tunable drug release from the nanocarrier through enhanced diffusion from the liposome membrane are demonstrated. Cytotoxicity assays using MCF-7, 4T1, and NIH3T3 cell lines exhibit no confrontational influence of nanoparticles on cell viability up to 125 µg/ml. The PD-1 antibody on the surface of the hybrid nanocarrier allows for selective delivery to breast cancer tumors and low biodistribution to other tissues. Our results affirm that the developed ultrasound-activated piezoelectric nanoparticles have great potential as multifunctional platforms with sustainable release profiles for the delivery of hydrophobic drugs to breast cancer, especially when the ability for adequate labeling and cell monitoring is valued.

An Electroconductive, Thermosensitive, and Injectable Chitosan/Pluronic/Gold-Decorated Cellulose Nanofiber Hydrogel as an Efficient Carrier for Regeneration of Cardiac Tissue.

Myocardial infarction is a major cause of death worldwide and remains a social and healthcare burden. Injectable hydrogels with the ability to locally deliver drugs or cells to the damaged area can revolutionize the treatment of heart diseases. Herein, we formulate a thermo-responsive and injectable hydrogel based on conjugated chitosan/poloxamers for cardiac repair. To tailor the mechanical properties and electrical signal transmission, gold nanoparticles (AuNPs) with an average diameter of 50 nm were physically bonded to oxidized bacterial nanocellulose fibers (OBC) and added to the thermosensitive hydrogel at the ratio of 1% w/v. The prepared hydrogels have a porous structure with open pore channels in the range of 50−200 µm. Shear rate sweep measurements demonstrate a reversible phase transition from sol to gel with increasing temperature and a gelation time of 5 min. The hydrogels show a shear-thinning behavior with a shear modulus ranging from 1 to 12 kPa dependent on gold concentration. Electrical conductivity studies reveal that the conductance of the polymer matrix is 6 × 10−2 S/m at 75 mM Au. In vitro cytocompatibility assays by H9C2 cells show high biocompatibility (cell viability of >90% after 72 h incubation) with good cell adhesion. In conclusion, the developed nanocomposite hydrogel has great potential for use as an injectable biomaterial for cardiac tissue regeneration.

Multilayered Mesoporous Composite Nanostructures for Highly Sensitive Label-Free Quantification of Cardiac Troponin-I.

Cardiac troponin-I (cTnI) is a well-known biomarker for the diagnosis and control of acute myocardial infarction in clinical practice. To improve the accuracy and reliability of cTnI electrochemical immunosensors, we propose a multilayer nanostructure consisting of Fe3O4-COOH labeled anti-cTnI monoclonal antibody (Fe3O4-COOH-Ab1) and anti-cTnI polyclonal antibody (Ab2) conjugated on Au-Ag nanoparticles (NPs) decorated on a metal-organic framework (Au-Ag@ZIF-67-Ab2). In this design, Fe3O4-COOH was used for separation of cTnI in specimens and signal amplification, hierarchical porous ZIF-67 extremely enhanced the specific surface area, and Au-Ag NPs synergically promoted the conductivity and sensitivity. They were additionally employed as an immobilization platform to enhance antibody loading. Electron microscopy images indicated that Ag-Au NPs with an average diameter of 1.9 ± 0.5 nm were uniformly decorated on plate-like ZIF-67 particles (with average size of 690 nm) without any agglomeration. Several electrochemical assays were implemented to precisely evaluate the immunosensor performance. The square wave voltammetry technique exhibited the best performance with a sensitivity of 0.98 mA mL cm-2 ng-1 and a detection limit of 0.047 pg mL-1 in the linear range of 0.04 to 8 ng mL-1.

High Yield of CO and Synchronous S Recovery from the Conversion of CO2 and H2S in Natural Gas Based on a Novel Electrochemical Reactor.

H2S and CO2 are the main impurities in raw natural gas, which needs to be purified before use. However, the comprehensive utilization of H2S and CO2 has been ignored. Herein, we proposed a fully resource-based method to convert toxic gas H2S and greenhouse gas CO2 synchronously into CO and elemental S by using a novel electrochemical reactor. The special designs include that, in the anodic chamber, H2S was oxidized rapidly to S based on the I-/I3- cyclic redox system to avoid anode passivation. On the other hand, in the cathodic chamber, CO2 was rapidly and selectively reduced to CO based on a porous carbon gas diffusion electrode (GDE) modified with polytetrafluoroethylene and cobalt phthalocyanine (CoPc). A high Faraday efficiency (>95%) toward CO was achieved due to the enhanced mass transfer of CO2 on the GDE and the presence of the selective CoPc catalyst. The maximum energy efficiency of the system was more than 72.41% with a current density of over 50 mA/cm2, which was 12.5 times higher than what was previously reported on the H2S treatment system. The yields of S and CO were 24.94 mg·cm-2·h-1 and 19.93 mL·cm-2·h-1, respectively. A model analysis determined that the operation cost of the synchronous utilization of H2S and CO2 method was slightly lower than that of the single utilization of H2S in the existing natural gas purification technology. Overall, this paper provides efficient and simultaneous conversion of H2S and CO2 into S and CO.

Green Electrospun Membranes Based on Chitosan/Amino-Functionalized Nanoclay Composite Fibers for Cationic Dye Removal: Synthesis and Kinetic Studies.

Chitosan/poly(vinyl alcohol)/amino-functionalized montmorillonite nanocomposite electrospun membranes with enhanced adsorption capacity and thermomechanical properties were fabricated and utilized for the removal of a model cationic dye (Basic Blue 41). Effects of nanofiller concentrations (up to 3.0 wt %) on the morphology and size of the nanofibers as well as the porosity and thermomechanical properties of the nanocomposite membranes are studied. It is shown that the incorporation of the nanoclay particles with ∼10 nm lateral sizes into the polymer increases the size of the pores by about 80%. To demonstrate the efficiency of the adsorbents, the dye removal rate is investigated as a function of pH, adsorbent dosage, dye concentration, and nanofiller loading. The highest and fastest dye removal occurs for the nanofibrous membranes containing 2 wt % nanofiller, where about 80% of the cationic dye is removed after 15 min. This performance is at least 20% better than the pristine chitosan/poly(vinyl alcohol) membrane. The thermal stability and compression resistance of the nanocomposite membranes are found to be higher than those of the pristine membrane. In addition, reusability studies show that the dye removal performance of this nanocomposite membrane reduces by only about 5% over four cycles. The adsorption kinetics is explained by the Langmuir isotherm model and is expressed by a pseudo-second-order kinetic mechanism that determines a spontaneous chemisorption process. The results of this study provide a valuable perspective on the fabrication of high-performance, reusable, and efficient electrospun fibrous nanocomposite adsorbents.

Biomimetic nanoengineered scaffold for enhanced full-thickness cutaneous wound healing.

Wound healing is a complex process based on the coordinated signaling molecules and dynamic interactions between the engineered scaffold and newly formed tissue. So far, most of the engineered scaffolds used for the healing of full-thickness skin wounds do not mimic the natural extracellular matrix (ECM) complexity and therefore are not able to provide an appropriate niche for endogenous tissue regeneration [1]. To address this gap and to accelerate the wound healing process, we present biomimetic bilayer scaffolds compositing of gelatin nanofibers (GFS) and photocrosslinkable composite hydrogels loaded with epidermal growth factors (EGF). The nanofibers operate as the dermis layer, and EGF-loaded composite hydrogels acted as the epidermis matrix for the full-thickness wound healing application. The hydrogels are composed of gelatin metacryloyl (GelMA) modified with silicate nanoplatelets (Laponite). To overcome the challenges of transdermal delivery of EGF, including short half-life and lack of efficient formulation precise, controlled delivery was attained by immobilization of EGF on Laponite. It is shown that the addition of 1wt% silicate nanoplatelet increases the compressive modulus of the hydrogels by 170%. In vitro wound closure analysis also demonstrated improved adhesion of the scaffolds to the native tissue by 3.5 folds. Moreover, the tunable hemostatic ability of the scaffolds due to the negatively charged nanoplatelets is shown. In an established excisional full-thickness wound model, an enhanced wound closure (up to 93.1 ± 1.5%) after 14 days relative to controls (GFS and saline-treated groups) is demonstrated. The engineered adhesive and hemostatic scaffolds with sustained release of the growth factors have the potential to stimulate complete skin regeneration for full-thickness wound healing.

Nanoengineered shear-thinning and bioprintable hydrogel as a versatile platform for biomedical applications.

The development of bioinks based on shear-thinning and self-healing hydrogels has recently attracted significant attention for constructing complex three-dimensional physiological microenvironments. For extrusion-based bioprinting, it is challenging to provide high structural reliability and resolution of printed structures while protecting cells from shear forces during printing. Herein, we present shear-thinning and printable hydrogels based on silicate nanomaterials, laponite (LA), and glycosaminoglycan nanoparticles (GAGNPs) for bioprinting applications. Nanocomposite hydrogels (GLgels) were rapidly formed within seconds due to the interactions between the negatively charged groups of GAGNPs and the edges of LA. The shear-thinning behavior of the hydrogel protected encapsulated cells from aggressive shear stresses during bioprinting. The bioinks could be printed straightforwardly into shape-persistent and free-standing structures with high aspect ratios. Rheological studies demonstrated fast recovery of GLgels over multiple strain cycles. In vitro studies confirmed the ability of GLgels to support cell growth, proliferation, and spreading. In vitro osteogenic differentiation of pre-osteoblasts murine bone marrow stromal cells encapsulated inside the GLgels was also demonstrated through evaluation of ALP activity and calcium deposition. The subcutaneous implantation of the GLgel in rats confirmed its in vivo biocompatibility and biodegradability. The engineered shear-thinning hydrogel with osteoinductive characteristics can be used as a new bioink for 3D printing of constructs for bone tissue engineering applications.

Solution Processing and Self-Organization of PbS Quantum Dots Passivated with Formamidinium Lead Iodide (FAPbI3).

Solution-processed lead sulfide quantum dots (PbS QDs) are very attractive as NIR-active semiconductors for the fabrication of cost-efficient optoelectronic devices. To control the thin film carrier transport, as well as stability, surface passivation is of crucial importance. Here, we present the successful surface passivation of PbS QDs by the formamidinium lead iodide (FAPbI3) ligand. An effective procedure for the fabrication of FAPbI3-passivated PbS QDs through a binary-phase ligand exchange protocol in hexane and n-methylformamide is demonstrated. It is shown that this solution-processed ligand exchange drastically changes the photoluminescence intensity, exciton recombination dynamics, and carrier lifetime of the nanocrystals. The solution casting of the ligand-exchanged nanocrystals into thin films results in the periodic ordering of QDs in a square superlattice with close contacts. Planar graphene/QD photodetectors fabricated with PbS QDs passivated with FAPbI3 show substantially increased thermal stability as compared to similar devices using PbS QDs passivated with commonly used methylammonium lead iodide.

Friction Stir Welding and Friction Spot Stir Welding Processes of Polymers-State of the Art.

In the last decade, the friction stir welding of polymers has been increasingly investigated by the means of more and more sophisticated approaches. Since the early studies, which were aimed at proving the feasibility of the process for polymers and identifying suitable processing windows, great improvements have been achieved. This owes to the increasing care of academic researchers and industrial demands. These improvements have their roots in the promising results from pioneer studies; however, they are also the fruits of the adoption of more comprehensive approaches and the multidisciplinary analyses of results. The introduction of instrumented machines has enabled the online measurement of processing loads and temperature, and critical understanding of the principal aspects affecting the material flow and welds quality. Such improvements are also clearly demonstrated by the increase of the strength of recent joints (up to 99% of joining efficiency) as compared to those reached in early researches (almost 47%). This article provides a comprehensive review of the recent progresses on the process fundamentals, quality assessment and the influence of process parameters on the mechanical behavior. In addition, emphasis is given to new developments and future perspectives.

In situ synthesis of quasi-needle-like bimetallic organic frameworks on highly porous graphene scaffolds for efficient electrocatalytic water oxidation.

We present enhanced electrocatalytic activity of three-dimensional graphene scaffolds by decoration with one-dimensional CoxNi1-x MOF nanostructures (0 ≤x≤ 1). The decreased overpotential and fast kinetics of the oxygen evolution reaction as compared with the existing materials are shown. The developed bimetallic MOF/3DG composites have great potential to be used in electrocatalytic water oxidation.

Core-sheath gelatin based electrospun nanofibers for dual delivery release of biomolecules and therapeutics.

Coaxial electrospinning with the ability to use simultaneously two separate solvents provides a promising strategy for drug delivery. Nevertheless, controlled release of hydrophilic and sensitive therapeutics from slow biodegradable polymers is still challenging. To address this gap, we fabricated core-sheath fibers for dual delivery of lysozyme, as a model protein, and phenytoin sodium as a small therapeutic molecule. The sheath was processed by a gelatin solution while the core fibers were fabricated from an aqueous gelatin/PVA solution. Microstructural studies by transmission and scanning electron microscopy reveal the formation of homogeneous core-sheath nanofibers with an outer and inner diameter of 180 ± 48 nm and 106 ± 30 nm, respectively. Thermal gravimetric analysis determines that the mass loss of the core-sheath fibers fall between the mass loss values of individual sheath and core fibers. Swelling studies indicate higher water absorption of the core-sheath mat compared to the separate sheath and core membranes. In vitro drug release studies in Phosphate Buffered Saline (PBS) determine sustained release of the therapeutics from the core-sheath structure. The release trails three stages including non-Fickian diffusion at the early stage followed by the Fickian diffusion mechanism. The present study shows a useful approach to design core-sheath nanofibrous membranes with controlled and programmable drug release profiles.

Biomimetic proteoglycan nanoparticles for growth factor immobilization and delivery.

The delivery of growth factors is often challenging due to their short half-life, low stability, and rapid deactivation. In native tissues, the sulfated residual of glycosaminoglycan (GAG) polymer chains of proteoglycans immobilizes growth factors through the proteoglycans'/proteins' complexation with nanoscale organization. These biological assemblies can influence growth factor-cell surface receptor interactions, cell differentiation, cell-cell signaling, and mechanical properties of the tissues. Here, we introduce a facile procedure to prepare novel biomimetic proteoglycan nanocarriers, based on naturally derived polymers, for the immobilization and controlled release of growth factors. We developed polyelectrolyte complex nanoparticles (PCNs) as growth factor nanocarriers, which mimic the dimensions, chemical composition, and growth factor immobilization of proteoglycans in native tissues. PCNs were prepared by a polymer-polymer pair reaction method and characterized for physicochemical properties. Fourier transform infrared spectroscopy (FTIR) analysis indicated that complexation occurred through electrostatic interactions. Transmission electron microscopy (TEM) results showed that the nanocarriers had a diameter of 60 ± 11 nm and 91 ± 33 nm for dermatan sulfate sodium salt-poly-l-lysine (DS-PLL) and gum tragacanth-poly-l-lysine (GT-PLL) complexes, respectively. The colloidal nanoparticles were stable due to their negative zeta potential, i.e.-25 ± 4 mV for DS-PLL and -18 ± 3.5 mV for GT-PLL. Cytocompatibility of PCNs in contact with human bone marrow stromal cells (HS-5) was confirmed through a live/dead assay and metabolic activity measurement. In addition, vascular endothelial growth factor (VEGF) was used to evaluate the ability of PCNs to stabilize growth factors. The capability of PCNs to preserve VEGF activity for up to 21 days was confirmed by analyzing the metabolic and mitogenic characteristics of human umbilical vein endothelial cells (HUVECs). Our results demonstrated the potential applications of these nanoparticles in therapeutic delivery for tissue regeneration applications.