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Small-scale and high-performance energy storage devices have drawn tremendous attention with their portable, lightweight, and multi-functionalized features. Here, we present a foldable supercapacitor with affordable flexibility by adopting a developed design and electrode material system as a way to extend usability. Notably, to resolve the limited energy density of conventional capacitors, we successfully synthesize the CoO/NiCo-layered double hydroxide (LDH) core-shell nanostructure on Ni framework as a cathode material. Further, glucose-based activated carbon (GBAC) is utilized for the anode. The CoO/NiCo-LDH electrodes exhibited a high specific capacitance of ∼284.8 mAh g

Highly-wrinkled graphene oxide (GO) films effectively inhibit or kill bacteria.

In recent years, bone tissue engineering (BTE) has made significant progress in promoting the direct and functional connection between bone and graft, including osseointegration and osteoconduction, to facilitate the healing of damaged bone tissues. Herein, we introduce a new, environmentally friendly, and cost-effective method for synthesizing reduced graphene oxide (rGO) and hydroxyapatite (HAp). The method uses epigallocatechin-3-O-gallate (EGCG) as a reducing agent to synthesize rGO (E-rGO), and HAp powder is obtained from Atlantic bluefin tuna (Thunnus thynnus). The physicochemical analysis indicated that the E-rGO/HAp composites had exceptional properties for use as BTE scaffolds, as well as high purity. Moreover, we discovered that E-rGO/HAp composites facilitated not only proliferation, but also early and late osteogenic differentiation of human mesenchymal stem cells (hMSCs). Our work suggests that E-rGO/HAp composites may play a significant role in promoting the spontaneous osteogenic differentiation of hMSCs, and we envision that the E-rGO/HAp composites could serve as promising candidates for BTE scaffolds, stem cell differentiation stimulators, and implantable device components due to their biocompatible and bioactive properties. Overall, we suggest a new approach for developing cost-effective and environmentally friendly E-rGO/HAp composite materials for BTE application.

Third harmonic generation from freestanding and glass-supported ultrathin β-Ga2O3 nanomembranes. The surface and bulk contributions of nonlinear optical harmonic generation.

A visual observation of the bending angle changes for the novel and easy detection of proteins is introduced in this study by fabricating bovine serum albumin (BSA) imprinted hydrogel strips with a one sided 3D porous structure using a combination of polystyrene colloidal crystal templating and the molecular imprinting approach using BSA as the template protein and several functional monomers.

A bacteria-infected wound can lead to being life-threatening and raises a great economic burden on the patient. Here, we developed polyethylenimine 1.8k (PEI

Biofabrication approaches, such as three-dimensional (3D) bioprinting of hydrogels, have recently garnered increasing attention, especially in the construction of 3D structures that mimic the complexity of tissues and organs with the capacity for cytocompatibility and post-printing cellular development. However, some printed gels show poor stability and maintain less shape fidelity if parameters such as polymer nature, viscosity, shear-thinning behavior, and crosslinking are affected. Therefore, researchers have incorporated various nanomaterials as bioactive fillers into polymeric hydrogels to address these limitations. Carbon-family nanomaterials (CFNs), hydroxyapatites, nanosilicates, and strontium carbonates have been incorporated into printed gels for application in various biomedical fields. In this review, following the compilation of research publications on CFNs-containing printable gels in various tissue engineering applications, we discuss the types of bioprinters, the prerequisites of bioink and biomaterial ink, as well as the progress and challenges of CFNs-containing printable gels in this field.

In recent years, bone tissue engineering (BTE) has made significant progress in promoting the direct and functional connection between bone and graft, including osseointegration and osteoconduction, to facilitate the healing of damaged bone tissues. Herein, we introduce a new, environmentally friendly, and cost-effective method for synthesizing reduced graphene oxide (rGO) and hydroxyapatite (HAp). The method uses epigallocatechin-3-O-gallate (EGCG) as a reducing agent to synthesize rGO (E-rGO), and HAp powder is obtained from Atlantic bluefin tuna (Thunnus thynnus). The physicochemical analysis indicated that the E-rGO/HAp composites had exceptional properties for use as BTE scaffolds, as well as high purity. Moreover, we discovered that E-rGO/HAp composites facilitated not only the proliferation, but also early and late osteogenic differentiation of human mesenchymal stem cells (hMSCs). Our work suggests that E-rGO/HAp composites may play a significant role in promoting the spontaneous osteogenic differentiation of hMSCs, and we envision that E-rGO/HAp composites could serve as promising candidates for BTE scaffolds, stem-cell differentiation stimulators, and implantable device components because of their biocompatible and bioactive properties. Overall, we suggest a new approach for developing cost-effective and environmentally friendly E-rGO/HAp composite materials for BTE application.

Resistive random-access memories (RRAMs) based on metal-oxide thin films have been studied extensively for application as synaptic devices in neuromorphic systems. The use of graphene oxide (GO) as a switching layer offers an exciting alternative to other materials such as metal-oxides. For a GO-based RRAM device to be used as a synapse device, the gradual conductance modulation is generally required to imitate adaptive synaptic weight change. However, there have been few studies demonstrating synaptic behavior with gradual memory modulation from the perspective of realizing application in neuromorphic scenarios. We present a newly developed RRAM device fabricated by implementing close-packed GO layers on a highly doped Si wafer to yield a gradual modulation of the memory as a function of the number of input pulses. By using flow-enabled self-assembly, highly uniform GO thin films can be formed on flat Si wafers in a rapid and simple process. The switching mechanism was explored through proposed scenarios reconstructing the density change of the sp2 cluster in the GO layer, resulting in a gradual conductance modulation. Finally, through a pattern-recognition simulation with a modified national institute of standards and technology database, the feasibility of using close-packed GO layers as synapse devices was successfully demonstrated.

Three-dimensional (3D) bioprinting has attracted considerable attention for producing 3D engineered cellular microenvironments that replicate complex and sophisticated native extracellular matrices (ECM) as well as the spatiotemporal gradients of numerous physicochemical and biological cues. Although various hydrogel-based bioinks have been reported, the development of advanced bioink materials that can reproduce the complexity of ECM accurately and mimic the intrinsic property of laden cells is still a challenge. This paper reports 3D printable bioinks composed of phenol-rich gelatin (GHPA) and graphene oxide (GO) as a component for a myogenesis-inducing material, which can form a hydrogel network in situ by a dual enzyme-mediated cross-linking reaction. The in situ curable GO/GHPA hydrogel can be utilized successfully as 3D-printable bioinks to provide suitable cellular microenvironments with facilitated myogenic differentiation of C2C12 skeletal myoblasts. Overall, we suggest that functional bioinks may be useful in muscle tissue engineering and regenerative medicine.

Directed self-assembly (DSA) of block copolymers (BCPs) has garnered much attention due to its excellent pattern resolution, simple process, and good compatibility with many other lithography methods for useful nanodevice applications. Here, we present a BCP-based multiple nanopatterning process to achieve three-dimensional (3D) pattern formation of metal/oxide hybrid nanostructures. We employed a self-assembled sub-20 nm SiOx line pattern as a master mold for nanotransfer printing (nTP) to generate a cross-bar array. By using the transfer-printed cross-bar structures as BCP-guiding templates, we can obtain well-ordered BCP microdomains in the distinct spaces of the nanotemplates through a confined BCP self-assembly process. We also demonstrate the morphological evolution of a cylinder-forming BCP by controlling the BCP film thickness, showing a clear morphological transition from cylinders to spheres in the designated nanospaces. Furthermore, we demonstrate how to control the number of BCP spheres within the cross-bar 3D pattern by adjusting the printing angle of the multiple nTP process to provide a suitable area for spontaneous BCP accommodation. This multiple-patterning-based approach is applicable to useful 3D nanofabrication of various devices with complex hybrid nanostructures.

Nanotransfer printing (nTP) has attracted much attention due to its high pattern resolution, simple process, and low processing cost for useful nanofabrication. Here, we introduce a thermally assisted nTP (T-nTP) process for the effective fabrication of various periodic three-dimensional (3D) nanosheets, such as concavo-convex lines, spine lines, square domes, and complex multi-line patterns. The T-nTP method allows continuous nanoscale 3D patterns with functionality to be transferred onto both rigid and flexible substrates by heat without any collapse of uniform convex nanostructures with nanochannels. We also show the pattern formation of multi-layered hybrid structures consisting of two or more materials by T-nTP. Furthermore, the formation of silicon oxide nanodots (0D) within a printed metallic nanowave structure (3D) can be achieved by the combined method of T-nTP and the self-assembly of poly(styrene-b-dimethylsiloxane) (PS-b-PDMS) block copolymers. Moreover, we demonstrate how to obtain well-defined oxide-metal hybrid nanostructures (0D-in-3D) through the spontaneous accommodation of PDMS spheres in the confined spaces of an Au-wave nanotemplate. This approach is applicable during the nanofabrication of various high-resolution devices with complex geometrical nanopatterns.

As a model quasi-2D network intercalation electrodes, niobium pentoxide (Nb2O5) has gained numerous attention in electrochemical materials because of its structural stability and high safety. Nevertheless, Nb2O5 exhibits the inherent low conductivity of transition metal oxides, which limits the rate of ionic diffusion and charge transfer. To overcome the drawbacks, the nanoscale Nb2O5 can be synthesized to improve electrochemical performance. Here, we prepared the flower-like orthorhombic Nb2O5 (i.e., T-Nb2O5) nanostructures to evaluate the effect of Nb2O5 nanoparticle morphology associated with crystallinity for lithium-ion batteries (LIBs) anode. T-Nb2O5-2 displays superior crystallinity, pore structure, capacity, reversibility, and cycling stability. Specifically, T-Nb2O5-2 exhibits the initial charge/discharge capacity of 289 and 525 mAh g−1 at 0.1 C, and after 100 cycles, the capacity is 178.2 mAh g−1 at 1 C when the solvothermal time is 16 h. This study shows that Nb2O5 with good crystallinity can slow down the volume expansion and structural deformation generated during the intercalation–deintercalation of Li-ions. We believe that the specified Nb2O5 presented in this work has great potential as a promising candidate for high-performance LIB anodes.

Nb2O5 has attracted much attention in various research filed such as hybrid capacitors, photo/electrocatalysis, and especially Li-ion batteries (LIBs) due to stable structure and high safety. Nevertheless, its low electronic conductivity (~ 3×10−6 S cm−1) degrades Li-storage performance that limits the practical use in LIBs. Here, we present a facile method for synthesis of T-Nb2O5 nanospheres/reduced graphene oxide composites by using niobium oxalate and bituminous coal as raw materials via a solvothermal method and subsequent calcination to enhance the conductivity of Nb2O5. In this work, the prepared Nb2O5 particles have excellent crystallinity that can be uniformly distributed onto the surface of the rGO layer to form Nb2O5/rGO composites. The electrochemical properties indicate that Nb2O5/rGO electrodes exhibit outstanding capacity, excellent reversibility, and superior cycle stability compared to other transition metal oxide-based electrodes. Notably, the initial capacities of the Nb2O5/rGO electrode at 0.02 A g−1 are 603 and 1104 mAh g−1, and the capacity still maintained 332 mAh g−1 after 100 cycles at 0.2 A g−1. Our synthetic approach provides a viable route to produce anode materials in a composite form facilitating nanostructured Nb2O5 with rGO exfoliated from bituminous coal for excellent performance in LIBs.

Cells respond directly to the chemical and topographical cues of the engineered substrate. To date, recent extensive studies have been witnessed on the wide development of biomimetic substrates that can regulate the cellular behaviors by establishing the specific cues of the substrate. It is well known that the topographical features with nanoscale and microscale strongly modulate the behaviors of cells, including adhesion, migration, proliferation, and differentiation. Herein, we present a simple and robust strategy to generate the patterned arrays of reduced graphene oxide (rGO) on a substrate to be used for the cellular interfaces. The rGO patterned arrays were prepared by an evaporative self-assembly process, which is a highly efficient technique for the controlled deposition of rGO sheets on a flat substrate. Such periodic patterned arrays of rGO could be utilized as a micron topographic substratum for living cell culture to observe the growth and alignment behaviors of C2C12 skeletal and vascular smooth muscle cells (VSMCs). The exquisite evaluations showed that both cells were regularly grown along the rGO patterned arrays leading to the well-defined contact guidance, but the only C2C12 myoblasts exhibited slightly higher level in the morphological alignment features to the rGO patterned arrays, compared to the VSMCs. Our findings suggest that the nanotextured thin films and patterned arrays of rGO can serve as promising biomimetic substrates for skeletal muscle cells and provide subtle effects on cellular morphology discriminating in their responses.

Nb2O5, as a potential electrochemical material, has been studied extensively due to its superior volumetric stability and safety. In the paper, we report a novel method for the synthesis of a T-Nb2...

We have synthesized binary reduced-graphene-oxide (RGO)/metal-oxide (Ni(OH)2, NiO, MnO2, and Fe3O4) nanocomposites by using a facile hydrothermal process. The morphology and the structure of the composite are confirmed by using x-ray diffraction (XRD), high-resolution transmission electron microscope (HRTEM), field-emission scanning electron microscopy (FESEM) and Raman spectroscopy. The electric capacitances that have been achieved for the nanocomposites at a current density of 1 A/g are 55, 140, 150 and 183 F/g for RGO/Fe3O4, RGO/Ni(OH)2, RGO/NiO and RGO/MnO2, respectively. Among them, RGO/MnO2 having the best electric capacity was used for preparing a current collector electrode by using various methods to attach the RGO/MnO2 nanocomposite to nickel foams. The supercapacitor performances of differently prepared current collector electrodes were tested, and the electric capacities found with the nanocomposites having a current density of 1 A/g are 28, 53, 112 and 212 F/g when the two-step drop method, the hydrothermal method, the doctor-blade method and the nanocomposite-drop method were used, respectively. Compared to a single metal-oxide, RGO/MnO2 nanocomposites show a superior electric conductivity, an electric capacity and a charge/discharge efficiency for supercapacitor performance, indicating that the RGO/metal-oxide nanocomposite is a promising material for supercapacitor applications.

Wound healing is the dynamic tissue regeneration process replacing devitalized and missing tissue layers. With the development of photomedicine techniques in wound healing, safe and noninvasive photobiomodulation therapy is receiving attention. Effective wound management in photobiomodulation is challenged, however, by limited control of the geometrical mismatches on the injured skin surface. Here, adhesive hyaluronic acid–based gelatin nanofibrous membranes integrated with multiple light-emitting diode (LED) arrays are developed as a skin-attachable patch. The nanofibrous wound dressing is expected to mimic the three-dimensional structure of the extracellular matrix, and its adhesiveness allows tight coupling between the wound sites and the flexible LED patch. Experimental results demonstrate that our medical device accelerates the initial wound healing process by the synergetic effects of the wound dressing and LED irradiation. Our proposed technology promises progress for wound healing management and other biomedical applications.

Conventional bioinert bone grafts often have led to failure in osseointegration due to low bioactivity, thus much effort has been made up to date to find alternatives. Recently, MXene nanoparticles (NPs) have shown prominent results as a rising material by possessing an osteogenic potential to facilitate the bioactivity of bone grafts or scaffolds, which can be attributed to the unique repeating atomic structure of two carbon layers existing between three titanium layers. In this study, we produced MXene NPs-integrated the ternary nanofibrous matrices of poly(L-lactide-co-ε-caprolactone, PLCL) and collagen (Col) decorated with MXene NPs (i.e., PLCL/Col/MXene), as novel scaffolds for bone tissue engineering, via electrospinning to explore the potential benefits for the spontaneous osteogenic differentiation of MC3T3-E1 preosteoblasts. The cultured cells on the physicochemical properties of the nanofibrous PLCL/Col/MXene-based materials revealed favorable interactions with the supportive matrices, highly suitable for the growth and survival of preosteoblasts. Furthermore, the combinatorial ternary material system of the PLCL/Col/MXene nanofibers obviously promoted spontaneous osteodifferentiation with positive cellular responses by providing effective microenvironments for osteogenesis. Therefore, our results suggest that the unprecedented biofunctional advantages of the MXene-integrated PLCL/Col nanofibrous matrices can be expanded to a wide range of strategies for the development of effective scaffolds in bone tissue regeneration. Graphical Abstract

Background Astaxanthin (AST) is known as a powerful antioxidant that affects the removal of active oxygen and inhibits the production of lipid peroxide caused by ultraviolet light. However, it is easily decomposed by heat or light during production and storage because of the unsaturated compound nature with a structural double bond. The activity of AST can be reduced and lose its antioxidant capability. Graphene oxide (GO) is an ultrathin nanomaterial produced by oxidizing layered graphite. The chemical combination of AST with GO can improve the dispersion properties to maintain structural stability and antioxidant activity because of the tightly bonded functionalized GO surface. Methods Layered GO films were used as nanocarriers for the AST molecule, which was produced via flow-enabled self-assembly and subsequent controlled solution deposition of RGD peptide and AST molecules. Synthesis of the GO-AST complex was also carried out for the optimized concentration. The characterization of prepared materials was analyzed through transmission electron microscopy (TEM), scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FT-IR), atomic force microscope (AFM), and Raman spectroscopy. Antioxidant activity was tested by 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2.2-diphenyl-1-picrylhydrazyl (DPPH) assays. The antibacterial effect and antioxidant effects were monitored for the ultrathin GO/RGD/AST Film. Further, reactive oxygen species (ROS) assay was used to evaluate the anti-inflammatory effects on L-929 fibroblasts. Results Cotreatment of GO-AST solution demonstrated a high antioxidant combined effect with a high ABTS and DPPH radicals scavenging activity. The GO/RGD/AST film was produced by the self-assembly process exhibited excellent antibacterial effects based on physicochemical damage against E. coli and S. aureus. In addition, the GO/RGD/AST film inhibited H2O2-induced intracellular ROS, suppressed the toxicity of lipopolysaccharide (LPS)-induced cells, and restored it, thereby exhibiting strong antioxidant and anti-inflammatory effects. Conclusion As GO nanocarrier-assisted AST exerted promising antioxidant and antibacterial reactions, presented a new concept to expand basic research into the field of tissue engineering.

An ionic device using a liquid Ga electrode in a 1 M NaOH solution is proposed to generate artificial neural spike signals. The oxidation and reduction at the liquid Ga surface were investigated for different bias voltages at 50 °C. When the positive sweep voltage from the starting voltage (

With the emerging trends and recent advances in nanotechnology, it has become increasingly possible to overcome current hurdles for bone and cartilage regeneration. Among the wide type of nanomaterials, graphene (G) and its derivatives (graphene-based materials, GBMs) have been highlighted due to the specific physicochemical and biological properties. In this review, we present the recent development of GBM-based scaffolds for bone and cartilage engineering, focusing on the formulation/shape/size-dependent characteristics, types of scaffold and modification, biocompatibility, bioactivity and underlying mechanism, drawback and prospect of each study. From the findings described herein, mechanical property, biocompatibility, osteogenic and chondrogenic property of GBM-based scaffolds could be significantly enhanced through various scaffold fabrication methods and conjugation with polymers/nanomaterials/drugs. In conclusion, the results presented in this review support the promising prospect of using GBM-based scaffolds for improved bone and cartilage tissue engineering. Although GBM-based scaffolds have some limitations to be overcome by future research, we expect further developments to provide innovative results and improve their clinical potential for bone and cartilage regeneration.

Two-dimensional graphene family nanomaterials (GFNs) are extensively studied by the researchers for their quantum size effect, large surface area, numerous reactive functional sites, and biocompatibility. The hybrid materials of GFNs exhibit an increased level of mechanical strength, optical, electronic, and catalytic activity due to their incorporation. The application of GFNs in the energy, environment, electric and electronic, personal care, and health sectors is abundant, which is not only by their unique physicochemical properties but also by their ease and large production by various synthetic approaches and economically inexpensiveness. Their general biomedical applications include bioimaging, biosensing, drug delivery, tissue engineering, killing the microbes, and demolishing the cancer tumor. The first chapter of this book describes definitions, synthetic methods, unique properties, and biomedical applications of GFNs, including graphene, graphene oxide, and reduced graphene oxide.

Two-dimensional nanomaterials have been widely explored by researchers due to their nanosized thickness and quantum size effect. They were layered double hydroxides, transition metal dichalcogenides, transition metal oxides, and synthetic silicate clays. Among the 2D nanomaterials, graphene and their derivatives were investigated extensively at first as they exhibited exceptional conductivity and a zero-band gap semimetal nature. Though graphene family nanomaterials (GFNs) were utilized for several physicochemical applications, including electronic, electric, mechanic, photonic, magnetic, and catalytic devices, their biomedical applications are still meritorious. Biosensor, bioimaging, drug delivery, tumor ablation, and tissue regeneration are some of them. The outlook of the present book chapters encompasses the preparation of GFNs, physicochemical properties, biomedical applications, biosafety, and their future directions.

Photobiomodulation (PBM) has received attention due to its potential for improving tissue function and enhancing regeneration in stroke. A lightweight, compact, and simple system of miniaturized electronic devices consisting of packaged light-emitting diodes (LEDs) that incorporates a flexible substrate for in vivo brain PBM in a mouse model is developed. Using this device platform, the preventive and therapeutic effects of PBM affixed to the exposed skull of mice in the photothrombosis and middle cerebral artery occlusion stroke model are evaluated. Among the wavelength range of 630, 850, and 940 nm LED array, the PBM with 630-nm LED array is proved to be the most effective for reducing the infarction volume and neurological impairment after ischemic stroke. Moreover, the PBM with 630 nm LED array remarkably improves the capability of spatial learning and memory in the chronic poststroke phase, attenuates AIM2 inflammasome activation and inflammasome-mediated pyroptosis, and modulates microglial polarization in the hippocampus and cortex 7 days following ischemic stroke. Thus, PBM may prevent tissue and functional damage in acute ischemic injury, thereby attenuating the development of cognitive impairment after stroke.

Background The implants of pure titanium (Ti) and its alloys can lead to implant failure because of their poor interaction with bone-associated cells during bone regeneration. Surface modification over implants has achieved successful implants for enhanced osseointegration. Herein, we report a robust strategy to implement bioactive surface modification for implant interface enabled by the combinatorial system of reduced graphene oxide (rGO)-coated sandblasted, large-grit, and acid-etched (SLA) Ti to impart benefits to the implant. Methods We prepared SLA Ti (ST) implants with different surface modifications [i.e., rGO and recombinant human bone morphogenetic protein-2 (rhBMP-2)] and investigated their dental tissue regenerating ability in animal models. We performed comparative studies in surface property, in vitro cellular behaviors, and in vivo osseointegration activity among different groups, including ST (control), rhBMP-2-immobilized ST (BI-ST), rhBMP-2-treated ST (BT-ST), and rGO-coated ST (R-ST). Results Spectroscopic, diffractometric, and microscopic analyses confirmed that rGO was coated well around the surfaces of Ti discs (for cell study) and implant fixtures (for animal study). Furthermore, in vitro and in vivo studies revealed that the R-ST group showed significantly better effects in cell attachment and proliferation, alkaline phosphatase activity, matrix mineralization, expression of osteogenesis-related genes and protein, and osseointegration than the control (ST), BI-ST, and BT-ST groups. Conclusion Hence, we suggest that the rGO-coated Ti can be a promising candidate for the application to dental or even orthopedic implants due to its ability to accelerate the healing rate with the high potential of osseointegration.

Third harmonic generation (THG) has proven its value in surface and interface characterization, high-contrast bio-imaging, and sub-wavelength light manipulation. Although THG is observed widely in general solid and liquid substances, when laser pulses are focused at nanometer-level ultra-thin films, the bulk THG has been reported to play the dominant role. However, there are still third harmonics (TH) generated at the surface of the thin-films, not inside the bulk solid - so-called surface TH, whose relative contribution has not been quantitatively revealed to date. In this study, we quantitatively characterized the surface and bulk contributions of THG at ultra-thin β-Ga

Graphene nanoribbons are a greatly intriguing form of nanomaterials owing to their unique properties that overcome the limitations associated with a zero bandgap of two-dimensional graphene at room temperature. Thus, the fabrication of graphene nanoribbons has garnered much attention for building high-performance field-effect transistors. Consequently, various methodologies reported previously have brought significant progress in the development of highly ordered graphene nanoribbons. Nonetheless, easy control in spatial arrangement and alignment of graphene nanoribbons on a large scale is still limited. In this study, we explored a facile, yet effective method for the fabrication of graphene nanoribbons by employing orientationally controlled electrospun polymeric nanowire etch-mask. We started with a thermal chemical vapor deposition process to prepare graphene monolayer, which was conveniently transferred onto a receiving substrate for electrospun polymer nanowires. The polymeric nanowires act as a robust etching barrier underlying graphene sheets to harvest arrays of the graphene nanoribbons. On varying the parametric control in the process, the size, morphology, and width of electrospun polymer nanowires were easily manipulated. Upon O2 plasma etching, highly aligned arrays of graphene nanoribbons were produced, and the sacrificial polymeric nanowires were completely removed. The graphene nanoribbons were used to implement field-effect transistors in a bottom-gated configuration. Such approaches could realistically yield a relatively improved current on&ndash, off ratio of ~30 higher than those associated with the usual micro-ribbon strategy, with the clear potential to realize reproducible high-performance devices.

Graphical Abstract The topographical interface of the extracellular environment has been appreciated as a principal biophysical regulator for modulating cell functions, such as adhesion, migration, proliferation, and differentiation. Despite the existed approaches that use two-dimensional nanomaterials to provide beneficial effects, opportunities evaluating their impact on stem cells remain open to elicit unprecedented cellular responses. Herein, we report an ultrathin cell-culture platform with potential-responsive nanoscale biointerfaces for monitoring mesenchymal stem cells (MSCs). We designed an intriguing nanostructured array through self-assembly of graphene oxide sheets and subsequent lithographical patterning method to produce chemophysically defined regions. MSCs cultured on anisotropic micro/nanoscale patterned substrate were spontaneously organized in a highly ordered configuration mainly due to the cell-repellent interactions. Moreover, the spatially aligned MSCs were spontaneously differentiated into smooth muscle cells upon the specific crosstalk between cells. This work provides a robust strategy for directing stem cells and differentiation, which can be utilized as a potential cell culture platform to understand cell–substrate or cell–cell interactions, further developing tissue repair and stem cell-based therapies. Supplementary Information The online version contains supplementary material available at 10.1186/s12951-021-01225-4.

During the last decade, graphene-family nanomaterials have been widely utilized, forming a composite with various polymers for potential applications in tissue engineering and regeneration due to their excellent physicochemical characteristics and biocompatibility. Above all, these graphene-family nanomaterials allow polymers to have novel biofunctional properties, while maintaining their intrinsic character. By virtue of this bioactivity of nanocomposites, they are able to modulate cellular behaviours such as cell attachment, proliferation and differentiation. In this study, the nanofibre composite matrices of poly(L-lactide-co-e-caprolactone) (PLCL) and laminin (Lam) functionalized with graphene oxide (GO) (PLCL/Lam/GO) were prepared via electrospinning to explore whether they have the potential to enhance the differentiation of hippocampal neuronal cells. The PLCL/Lam/GO nanofibre matrices could support the adhesion and proliferation of hippocampal neuronal cells by providing the extracellular matrix-like structure. Furthermore, these PLCL/Lam/GO composite matrices were found to promote neurite outgrowth and alignment from hippocampal neuronal cells through providing optimal microenvironments for neuronal differentiation. The underlying mechanism of this phenomenon was proposed according to the scenario in which neurite outgrowth was guided by biofunctional cues, such as Lam and GO, with nanofibre-mediated topographical cues, which upregulated the expression of some specific genes (i.e., DCX, MAP2 and Nestin) closely related to cytoskeletal interactions. In conclusion, it is suggested that these nanofibre composite matrices can be exploited to craft a range of strategies for the development of novel scaffolds to accelerate neural regeneration.

Background The excellent physicochemical properties of graphene-based materials, including graphene oxide (GO) and reduced GO (rGO), offer significant technological potential as multifunctional nanomaterials in biomedical fields. Lutein is a type of carotenoid that forms human macular pigments in the retina, where it inhibits harmful blue light and contributes to the strengthening of the antioxidant defense of retinal pigment epithelium cells. Methods Synthesis of the Lutein-rGO (Lu–rGO) complex was carried out for the optimized concentration. Then characterization of material was analyzed through ultraviolet-visible spectrophotometer (UV-Vis spectra), Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM). Antioxidant activity of Lu–rGO complex was measured by 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2.2-diphenyl-1-picrylhydrazyl (DPPH), glutathione (GSH) oxidation assay. Then, oxidative stress induction by blue light and analyzed intracellular reactive oxygen species (ROS). Results and Conclusion Based on the FT-IR measurement, the reduction efficiency defined by area was found to be 87.3%, the ID/IG ratio of 0.98 demonstrated by the Lu–rGO complex in the Raman spectrum was slightly higher than that of the original GO. The exhibited significant decrease in the peak intensities of the oxygen functional groups of the XPS spectra of the Lu–rGO complex was observed compared with the GO. In the TEM image for the Lu–rGO complex, folded and wrinkled nanostructures over the lutein-covered rGO surface were evidenced by tight molecular binding. The Lu–rGO complex provided superior DPPH and ABTS radical scavenging activity than GO and lutein alone, and the oxidation of GSH was suppressed. It was confirmed that the content of intracellular ROS and lysosomes, increased by blue light, was reduced after treatment with the Lu–rGO complex on ARPE-19 cells. In summary, graphene-based nanocarriers could function as preventative antioxidants during photochemical ROS generation based on the mechanism of antioxidant action., Graphical Abstract

Recently, black phosphorus (BP) has garnered great attention as one of newly emerging two-dimensional nanomaterials. Especially, the degraded platelets of BP in the physiological environment were shown to be nontoxic phosphate anions, which are a component of bone tissue and can be used for mineralization. Here, our study presents the potential of BP as biofunctional and biocompatible nanomaterials for the application to bone tissue engineering and regeneration. An ultrathin layer of BP nanodots (BPNDs) was created on a glass substrate by using a flow-enabled self-assembly process, which yielded a highly uniform deposition of BPNDs in a unique confined geometry. The BPND-coated substrates represented unprecedented favorable topographical microenvironments and supportive matrices suitable for the growth and survival of MC3T3-E1 preosteoblasts. The prepared substrates promoted the spontaneous osteodifferentiation of preosteoblasts, which had been confirmed by determining alkaline phosphatase activity and extracellular calcium deposition as early- and late-stage markers of osteogenic differentiation, respectively. Furthermore, the BPND-coated substrates upregulated the expression of some specific genes (i.e., RUNX2, OCN, OPN, and Vinculin) and proteins, which are closely related to osteogenesis. Conclusively, our BPND-coating strategy suggests that a biologically inert surface can be readily activated as a cell-favorable nanoplatform enabled with excellent biocompatibility and osteogenic ability.

Surface imprinting used for template recognition in nanocavities can be controlled and improved by surface morphological changes. Generally, the lithographic technique is used for surface patterning concerning sensing signal amplification in molecularly imprinted polymer (MIP) thin films. In this paper, we describe the effects of silanized silica molds on sensing the properties of MIP films. Porous imprinted poly(MAA–co–EGDMA) films were lithographically fabricated using silanized or non-treated normal silica replica molds to detect 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide as the standard template. The silanized mold MIP film (st-MIP) (Δf = −1021 Hz) exhibited a better sensing response than the non-treated normal MIP (n-MIP) (Δf = −978 Hz) because the imprinting effects, which occurred via functional groups on the silica surface, could be reduced through silane modification. Particularly, two non-imprinted (NIP) films (st-NIP and n-NIP) exhibited significantly different sensing responses. The st-NIP (Δfst-NIP = −332 Hz) films exhibited lower Δf values than the n-NIP film (Δfn-NIP = −610 Hz) owing to the remarkably reduced functionality against nonspecific adsorption. This phenomenon led to different imprinting factor (IF) values for the two MIP films (IFst-MIP = 3.38 and IFn-MIP = 1.86), which was calculated from the adsorbed 2,4-D mass per poly(MAA–co–EGDMA) unit weight (i.e., QMIP/QNIP). Moreover, it was found that the st-MIP film had better selectivity than the n-MIP film based on the sensing response of analogous herbicide solutions. As a result, it was revealed that the patterned molds’ chemical surface modification, which controls the surface functionality of imprinted films during photopolymerization, plays a role in fabricating enhanced sensing properties in patterned MIP films.

Background Titanium (Ti) has been utilized as hard tissue replacement owing to its superior mechanical and bioinert property, however, lack in tissue compatibility and biofunctionality has limited its clinical use. Reduced graphene oxide (rGO) is one of the graphene derivatives that possess extraordinary biofunctionality and are known to induce osseointegration in vitro and in vivo. In this study, rGO was uniformly coated by meniscus-dragging deposition (MDD) technique to fabricate rGO-Ti substrate for orthopedic and dental implant application. Methods The physicochemical characteristics of rGO-coated Ti (rGO-Ti) substrates were evaluated by atomic force microscopy, water contact angle, and Raman spectroscopy. Furthermore, human mesenchymal stem cells (hMSCs) were cultured on the rGO-Ti substrate, and then their cellular behaviors such as growth and osteogenic differentiation were determined by a cell counting kit-8 assay, alkaline phosphatase (ALP) activity assay, and alizarin red S staining. Results rGO was coated uniformly on Ti substrates by MDD process, which allowed a decrease in the surface roughness and contact angle of Ti substrates. While rGO-Ti substrates significantly increased cell proliferation after 7 days of incubation, they significantly promoted ALP activity and matrix mineralization, which are early and late differentiation markers, respectively. Conclusion It is suggested that rGO-Ti substrates can be effectively utilized as dental and orthopedic bone substitutes since these graphene derivatives have potent effects on stimulating the osteogenic differentiation of hMSCs and showed superior bioactivity and osteogenic potential.

Over the past few decades, carbon nanomaterials, including carbon nanofibers, nanocrystalline diamonds, fullerenes, carbon nanotubes, carbon nanodots, and graphene and its derivatives, have gained the attention of bioengineers and medical researchers as they possess extraordinary physicochemical, mechanical, thermal, and electrical properties. Recently, surface functionalization with carbon nanomaterials in dental and orthopedic implants has emerged as a novel strategy for reinforcement and as a bioactive cue due to their potential for osseointegration. Numerous developments in fabrication and biological studies of carbon nanostructures have provided various novel opportunities to expand their application to hard tissue regeneration and restoration. In this minireview, the recent research trends in surface functionalization of orthopedic and dental implants with coating carbon nanomaterials are summarized. In addition, some seminal methodologies for physicomechanical and electrochemical coatings are discussed. In conclusion, it is shown that further development of surface functionalization with carbon nanomaterials may provide innovative results with clinical potential for improved osseointegration after implantation.

A dataset in this report is regarding an article “Ultrathin Effective TiN Protective Films Prepared by Plasma-Enhanced Atomic Layer Deposition for High Performance Metallic Bipolar Plates of Polymer Electrolyte Membrane Fuel Cells” [1] . TiN (Titanium Nitride) thin films were deposited by Plasma-Enhanced Atomic Layer Deposition (PEALD) method using well known two types of precursor: using tetrakis(dimethylamino)titanium (TDMAT) and titanium tetrachloride (TiCl4), and plasma. Summarized reports, growth characteristics (growth rate as a function of each precursor pulse time, plasma power, precursor and plasma purge time, thickness depending on the number of PEALD cycles), each precursor structural information and the atomic force micrographs (AFM) data are herein demonstrated. For TDMAT-TiN, N2 plasma was used as a reactant whereas, H2+N2 plasma was used as TiCl4-TiN reactant. To apply the bipolar plate substrate, two types of TiN thin films were introduced into Stainless steel (SUS) 316L.

Patterning of surfaces with a simple strategy provides insights into the functional interfaces by suitable modification of the surface by novel techniques. Especially, highly ordered structural topographies and chemical features from the wide range of interfaces have been considered as important characteristics to understand the complex relationship between the surface chemistries and biological systems. Here, we report a simple fabrication method to create patterned surfaces over large areas using evaporative self-assembly that is designed to produce a sacrificial template and lithographic etch masks of polymeric stripe patterns, ranging from micrometer to nanoscale. By facilitating a roll-on-plate geometry, the periodically patterned surface structures formed by repetitive slip-stick motions were thoroughly examined to be used for the deposition of the Au nanoparticles decorated graphene oxide (i.e., AuNPs, ~21 nm) and the formation of conductive graphene channels. The fluorescently labeled thiol-modified DNA was applied on the patterned arrays of graphene oxide (GO)/AuNPs, and biotin-streptavidin sensitive devices built with graphene-based transistors (GFETs, effective mobility of ~320 cm2 V&minus, 1 s&minus, 1) were demonstrated as examples of the platform for the next-generation biosensors with the high sensing response up to ~1 nM of target analyte (i.e., streptavidin). Our strategy suggests that the stripe patterned arrays of polymer films as sacrificial templates can be a simple route to creating highly sensitive biointerfaces and highlighting the development of new chemically patterned surfaces composed of graphene-based nanomaterials.

Graphene, a two-dimensional (2D) carbon nanomaterial, has received great attention owing to its advantageous characteristics, including superior electrical, chemical and physical properties. In particular, exfoliation of graphite with strong oxidants has been explored to prepare a suspension of individual 2D graphene oxide (GO) nanosheets dispersed in various types of solvents. This colloidal suspension can readily be employed in a wide range of promising potential applications. However, one major challenge is to assemble such individual nanosheets on defined areas of surfaces forming specific structures. Here, we developed a simple and robust one-step strategy to create highly regular ordered nanostructures composed of chemically reduced graphene oxide (rGO) nanosheet building blocks on SiO2/Si or glass substrates over large areas. An aqueous suspension of rGO nanosheets dispersed in a volatile solvent was subjected to a confined geometry to induce a spontaneous formation of rGO patterned arrays with unprecedented regularity by utilizing both a controlled coffee ring effect and consecutive stick-slip motions of rGO solutions during the drying process. As a result, the generation of ultrathin nanotextured films in the form of micropatterns (i.e., concentric gradient rGO coffee rings) was effectively tailored. As a biological approach, to fully utilize patterned rGO associated with the nanoscale surface topography, we used these patterned rGO arrays as a biomimetic in vitro architecture to study interfacial interactions of living cells such as fibroblasts, myoblasts, and neuronal cells. The observed results show that the patterned rGO arrays can be used as manipulated cellular responsive templates to form living cell assemblies and related patterns that are useful for regenerative tissue engineering.

A dataset in this report is regarding an article “Ultrathin Effective TiN Protective Films Prepared by Plasma-Enhanced Atomic Layer Deposition for High Performance Metallic Bipolar Plates of Polymer Electrolyte Membrane Fuel Cells” [1]. TiN (Titanium Nitride) thin films were deposited by Plasma-Enhanced Atomic Layer Deposition (PEALD) method using well known two types of precursor: using tetrakis(dimethylamino)titanium (TDMAT) and titanium tetrachloride (TiCl4), and plasma. Summarized reports, growth characteristics (growth rate as a function of each precursor pulse time, plasma power, precursor and plasma purge time, thickness depending on the number of PEALD cycles), each precursor structural information and the atomic force micrographs (AFM) data are herein demonstrated. For TDMAT-TiN, N2 plasma was used as a reactant whereas, H2+N2 plasma was used as TiCl4-TiN reactant. To apply the bipolar plate substrate, two types of TiN thin films were introduced into Stainless steel (SUS) 316L.