Graphene and graphene oxide: biofunctionalization and applications in biotechnology

In silico bioactivity prediction of proteins interacting with graphene-based nanomaterials guides rational design of biosensor

Graphene-based nanomaterials have attracted significant attention for their potentials in biomedical and biotechnology applications in recent years, owing to the outstanding physical and chemical properties. However, the interaction mechanism and impact on biological activity of macro/micro biomolecules still require more concerns and further research in order to enhance their applicability in biosensors, etc. Herein, an integrated method has been developed to predict the protein bioactivity performance when interacting with nanomaterials for protein-based biosensor. Molecular dynamics simulation and molecular docking technique were consolidated to investigate several nanomaterials: C60 fullerene, single-walled carbon nanotube, pristine graphene and graphene oxide, and their effect when interacting with protein. The adsorption behavior, secondary structure changes and protein bioactivity changes were simulated, and the results of protein activity simulation were verified in combination with atomic force spectrum, circular dichroism spectrum fluorescence and electrochemical experiments. The best quantification alignment between bioactivity obtained by simulation and experiment measurements was further explored. The two proteins, RNase A and Exonuclease III, were regarded as analysis model for the proof of concept, and the prediction accuracy of protein bioactivity could reach up to 0.98. The study shows an easy-to-operate and systematic approach to predict the effects of graphene-based nanomaterials on protein bioactivity, which holds guiding significance for the design of protein-related biosensors. In addition, the proposed prediction model is not limited to carbon-based nanomaterials and can be extended to other types of nanomaterials. This facilitates the rapid, simple, and low-cost selection of efficient and biosafe nanomaterials candidates for protein-related applications in biosensing and biomedical systems.

Multiplex fluorescence loop-mediated isothermal amplification with lateral flow assay for rapid simultaneous detection of mecA and nuc genes in methicillin-resistant Staphylococcus aureus

BACKGROUND

Antibiotic-resistant bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), pose a significant threat to public health. Existing detection methods, like cultivation-based techniques, demand significant time and labor, while molecular diagnostic techniques, such as PCR, necessitate sophisticated instrumentation and skilled personnel. Although previous multiplex loop-mediated isothermal amplification assays based on fluorescent dyes (mfLAMP) offer simplicity and cost-effectiveness, they are prone to false-positive results. Therefore, developing a rapid and efficient multiplex assay for high-sensitivity MRSA is imperative to create a practical diagnostic tool for point-of-care testing.

RESULTS

Here, we developed a mfLAMP combined with a lateral flow assay (mfLAMP-LFA) for the visual and simultaneous detection of the mecA (PBP2a-specific marker) and nuc (S. aureus-specific marker) genes in MRSA. We optimized mfLAMP-LFA using graphene oxide (GO)-based purification and specific DNA probes and evaluated its sensitivity, specificity, and stability. Utilizing GO to mitigate false-positive results by acting as a trap for free DNA probes, the mfLAMP-LFA method successfully identified mecAf and nucf-probes, exhibiting distinct red, green, and yellow fluorescence signals. The detection sensitivity of the developed mfLAMP-LFA method (1 CFU mL-1 in phosphate-buffered saline (PBS)) was comparable to other highly sensitive MRSA detection methods (1 CFU mL-1 in PBS). Furthermore, the method demonstrated specificity for MRSA, detecting it in irrigation water samples within the desired range and achieving reliable recovery rates from spiked samples.

SIGNIFICANCE

This novel strategy is the first to incorporate GO into mfLAMP-LFA, enabling specific and sensitive MRSA detection and advancing rapid bacterial detection. This assay facilitates MRSA diagnostics, contributing to improved public health and food safety by delivering rapid, cost-effective point-of-care results. It enables the simultaneous detection of multiple bacteria, even in irrigation water samples artificially inoculated with MRSA, which contain aerobic bacteria at 2.7 × 102 CFU mL-1.

Nanomaterials in 4D Printing: Expanding the Frontiers of Advanced Manufacturing

As an innovative technology, four-dimentional (4D) printing is built upon the principles of three-dimentional (3D) printing with an additional dimension: time. While traditional 3D printing creates static objects, 4D printing generates "responsive 3D printed structures", enabling them to transform or self-assemble in response to external stimuli. Due to the dynamic nature, 4D printing has demonstrated tremendous potential in a range of industries, encompassing aerospace, healthcare, and intelligent devices. Nanotechnology has gained considerable attention owing to the exceptional properties and functions of nanomaterials. Incorporating nanomaterials into an intelligent matrix enhances the physiochemical properties of 4D printed constructs, introducing novel functions. This review provides a comprehensive overview of current applications of nanomaterials in 4D printing, exploring their synergistic potential to create dynamic and responsive structures. Nanomaterials play diverse roles as rheology modifiers, mechanical enhancers, function introducers, and more. The overarching goal of this review is to inspire researchers to delve into the vast potential of nanomaterial-enabled 4D printing, propelling advancements in this rapidly evolving field.

Aqueous Graphene Dispersion and Biofunctionalization via Enzymatic Oxidation of Tripeptides

Graphene, a 2D carbon material, possesses extraordinary mechanical, electrical, and thermal properties, making it highly attractive for various biological applications such as biosensing, biotherapeutics, and tissue engineering. However, the tendency of graphene sheets to aggregate and restack hinders its dispersion in water, limiting these applications. Peptides, with their defined amino acid sequences and versatile functionalities, are compelling molecules with which to modify graphene-aromatic amino acids can strengthen interactions through π-stacking and charged groups can be chosen to make the sheets dispersible and stable in water. Here, a facile and green method for covalently functionalizing and dispersing graphene using amphiphilic tripeptides, facilitated by a tyrosine phenol side chain, through an aqueous enzymatic oxidation process is demonstrated. The presence of a second aromatic side chain group enhances this interaction through non-covalent support via π-π stacking with the graphene surface. Futhermore, the addition of charged moieties originating from either ionizable amino acids or terminal groups facilitates profound interactions with water, resulting in the dispersion of the newly functionalized graphene in aqueous solutions. This biofunctionalization method resulted in ≈56% peptide loading on the graphene surface, leading to graphene dispersions that remain stable for months in aqueous solutions outperforming currently used surfactants.

A review of nanotechnology in enzyme cascade to address challenges in pre-treating biomass

Nanotechnology has become a revolutionary technique for improving the preliminary treatment of lignocellulosic biomass in the production of biofuels. Traditional methods of pre-treatment have encountered difficulties in effectively degrading the intricate lignocellulosic composition, thereby impeding the conversion of biomass into fermentable sugars. Nanotechnology has enabled the development of enzyme cascade processes that present a potential solution for addressing the limitations. The focus of this review article is to delve into the utilization of nanotechnology in the pretreatment of lignocellulosic biomass through enzyme cascade processes. The review commences with an analysis of the composition and structure of lignocellulosic biomass, followed by a discussion on the drawbacks associated with conventional pre-treatment techniques. The subsequent analysis explores the importance of efficient pre-treatment methods in the context of biofuel production. We thoroughly investigate the utilization of nanotechnology in the pre-treatment of enzyme cascades across three distinct sections. Nanomaterials for enzyme immobilization, enhanced enzyme stability and activity through nanotechnology, and nanocarriers for controlled enzyme delivery. Moreover, the techniques used to analyse nanomaterials and the interactions between enzymes and nanomaterials are introduced. This review emphasizes the significance of comprehending the mechanisms underlying the synergy between nanotechnology and enzymes establishing sustainable and environmentally friendly nanotechnology applications.

Distribution of oxygen-containing functional groups on defective graphene: properties engineering and Li adsorption

In this study, the distribution of oxygen-containing functional groups on graphene with vacancies and topological defects was systematically investigated using advanced computational methods and the structure models for multi-defect graphene oxides (GOs) were proposed. All potential adsorption sites were considered through an automated structure generation program to identify energetically favorable structures. Unlike the pristine graphene surface where oxygen-containing functional groups always aggregate with each other, we observed a tendency for them to preferentially adsorb near defects. Furthermore, they may also be distributed on the same side or both sides of the defective graphene. These multi-defect GOs can exhibit either metallic or semiconducting properties. Notably, upon adsorbing the same oxygen-containing functional groups onto the surface of defective graphene, their electronic characteristics become homogeneous. The coexistence of vacancy/topological defects and oxygen-containing functional groups within the graphene lattice introduces intriguing mechanical anisotropic properties to graphene, including the uncommon negative Poisson's ratio. Additionally, these materials exhibit anisotropic optical behavior, displaying heightened absorption within the infrared and visible regions compared to pristine graphene. Finally, it is found that Li atoms are adsorbed stably on the surfaces of multi-defect GOs via the formation of LinO/LimOH clusters. The research findings presented in this paper, encompassing the development of structural models for multi-defect GOs, could provide crucial insights into the properties and potential applications of graphene oxides.

Single-Step Low-Temperature Synthesis of Carbon Dots for Advanced Multiparametric Bioimaging Probe Applications

Carbon dots (CDs) have recently emerged in biomedical and agricultural domains, mainly for their probe applications in developing efficient sensors. However, the existing high-temperature approaches limit the industrial level scaling up to further translate them into different products by mass-scale fabrication of CDs. To address this, we have attempted to lower the synthesis temperature to 140 °C and synthesized different CDs using different organic acids and their combinations in a one-step approach (quantum yield 3.6% to 16.5%; average size 3 to 5 nm). Further, sensing applications of CDs have been explored in three different biological models, mainly Danio rerio (zebrafish) embryos, bacterial strains, and the Lactuca sativa (lettuce) plant. The 72 h exposure of D. rerio embryos to 0.5 and 1 mg/mL concentrations of CDs exhibited significant uptake without mortality, a 100% hatching rate, and nonsignificant alterations in heart rate. Bacterial bioimaging experiments revealed CD compatibility with Gram-positive (Bacillus subtilis) and Gram-negative (Serratia marcescens) strains without bactericidal effects. Furthermore, CDs demonstrated effective conduction and fluorescence within the vascular system of lettuce plants, indicating their potential as in vivo probes for plant tissues. The single-step low-temperature CD synthesis approach with efficient structural and optical properties enables the process as industrially viable to up-scale the technology readiness level. The bioimaging of CDs in different biological models indicates the possibility of developing a CD probe for diverse biosensing roles in diseases, metabolism, microbial contamination sensing, and more.

Impact of nanotechnology at heterogeneous interphases @ Sustainability

The 21st century information and communication industries have played the pivotal role of bio-sensing technologies, refining privacy policies for human performance, facilitating scientific innovation, shaping e-governance, and reinforcing public confidence using nanotechnology. Human body is a thermodynamic heat engine in providing effective mechanical work as a function of psyche, conventional fuel transformation into enriched protein meal, and balancing of work-life fulcrum. The triboelectric effect of rubbing surfaces, interfaces, and interphases is invincible from the large field of the planet to nanodomains.

Possible bi-stable structures of pyrenebutanoic acid-linked protein molecules adsorbed on graphene: theoretical study

We theoretically analyze possible multiple conformations of protein molecules immobilized by 1-pyrenebutanoic acid succinimidyl ester (PASE) linkers on graphene. The activation barrier between two bi-stable conformations exhibited by PASE is confirmed to be based on the steric hindrance effect between a hydrogen on the pyrene group and a hydrogen on the alkyl group of this molecule. Even after the protein is supplemented, this steric hindrance effect remains if the local structure of the linker consisting of an alkyl group and a pyrene group is maintained. Therefore, it is likely that the kinetic behavior of a protein immobilized with a single PASE linker exhibits an activation barrier-type energy surface between the bi-stable conformations on graphene. We discuss the expected protein sensors when this type of energy surface appears and provide a guideline for improving the sensitivity, especially as an oscillator-type biosensor.

Interplay of graphene-DNA interactions: Unveiling sensing potential of graphene materials

Graphene-based materials and DNA probes/nanostructures have emerged as building blocks for constructing powerful biosensors. Graphene-based materials possess exceptional properties, including two-dimensional atomically flat basal planes for biomolecule binding. DNA probes serve as excellent selective probes, exhibiting specific recognition capabilities toward diverse target analytes. Meanwhile, DNA nanostructures function as placement scaffolds, enabling the precise organization of molecular species at nanoscale and the positioning of complex biomolecular assays. The interplay of DNA probes/nanostructures and graphene-based materials has fostered the creation of intricate hybrid materials with user-defined architectures. This advancement has resulted in significant progress in developing novel biosensors for detecting DNA, RNA, small molecules, and proteins, as well as for DNA sequencing. Consequently, a profound understanding of the interactions between DNA and graphene-based materials is key to developing these biological devices. In this review, we systematically discussed the current comprehension of the interaction between DNA probes and graphene-based materials, and elucidated the latest advancements in DNA probe-graphene-based biosensors. Additionally, we concisely summarized recent research endeavors involving the deposition of DNA nanostructures on graphene-based materials and explored imminent biosensing applications by seamlessly integrating DNA nanostructures with graphene-based materials. Finally, we delineated the primary challenges and provided prospective insights into this rapidly developing field. We envision that this review will aid researchers in understanding the interactions between DNA and graphene-based materials, gaining deeper insight into the biosensing mechanisms of DNA-graphene-based biosensors, and designing novel biosensors for desired applications.

Theranostics: a multifaceted approach utilizing nano-biomaterials

Biomaterials play a vital role in targeting therapeutics. Over the years, several biomaterials have gained wide attention in the treatment and diagnosis of diseases. Scientists are trying to make more personalized treatments for different diseases, as well as discovering novel single agents that can be used for prognosis, medication administration, and keeping track of how a treatment works. Theranostics based on nano-biomaterials have higher sensitivity and specificity for disease management than conventional techniques. This review provides a concise overview of various biomaterials, including carbon-based materials like fullerenes, graphene, carbon nanotubes (CNTs), and carbon nanofibers, and their involvement in theranostics of different diseases. In addition, the involvement of imaging techniques for theranostics applications was overviewed. Theranostics is an emerging strategy that has great potential for enhancing the accuracy and efficacy of medicinal interventions. Despite the presence of obstacles such as disease heterogeneity, toxicity, reproducibility, uniformity, upscaling production, and regulatory hurdles, the field of medical research and development has great promise due to its ability to provide patients with personalised care, facilitate early identification, and enable focused treatment.

The effect of graphene and graphene oxide induced reactive oxygen species on polycaprolactone scaffolds for bone cancer applications

Bone cancer remains a critical healthcare problem. Among current clinical treatments, tumour resection is the most common strategy. It is usually effective but may present several limitations such as multiple operations, long hospital time, and the potential recurrence caused by the incomplete removal of cancer cells. To address these limitations, three-dimensional (3D) scaffolds fabricated through additive manufacturing have been researched for both bone cancer treatment and post-treatment rehabilitation. Polycaprolactone (PCL)-based scaffolds play an important role in bone regeneration, serving as a physical substrate to fill the defect site, recruiting cells, and promoting cell proliferation and differentiation, ultimately leading to the regeneration of the bone tissue without multiple surgical applications. Multiple advanced materials have been incorporated during the fabrication process to improve certain functions and/or modulate biological performances. Graphene-based nanomaterials, particularly graphene (G) and graphene oxide (GO), have been investigated both in vitro and in vivo, significantly improving the scaffold's physical, chemical, and biological properties, which strongly depend on the material type and concentration. A unique targeted inhibition effect on cancer cells was also discovered. However, limited research has been conducted on utilising graphene-based nanomaterials for both bone regeneration and bone cancer treatment, and there is no systematic study into the material- and dose-dependent effects, as well as the working mechanism on 3D scaffolds to realise these functions. This paper addresses these limitations by designing and fabricating PCL-based scaffolds containing different concentrations of G and GO and assessing their biological behaviour correlating it to the reactive oxygen species (ROS) release level. Results suggest that the ROS release from the scaffolds is a dominant mechanism that affects the biological behaviour of the scaffolds. ROS release also contributes to the inhibition effect on bone cancer due to healthy cells and cancer cells responding differently to ROS, and the osteogenesis results also present a certain correlation with ROS. These observations revealed a new route for realising bone cancer treatment and subsequent new bone regeneration, using a single dual-functional 3D scaffold.

Conductive GelMA/alginate/polypyrrole/graphene hydrogel as a potential scaffold for cardiac tissue engineering; Physiochemical, mechanical, and biological evaluations

Cardiac failure can be a life-threatening condition that, if left untreated, can have significant consequences. Functional hydrogel has emerged as a promising platform for cardiac tissue engineering. In the proposed study, gelatin methacrylate (GelMA) and alginate, as a primary matrix to maintain cell viability and proliferation, and polypyrrole and carboxyl-graphene, to improve mechanical and electrical properties, are thoroughly evaluated. Initially, a polymer blend of GelMA/Alginate (1:1) was prepared, and then the addition of 2-5 wt% of polypyrrole was evaluated. Next, the effect of incorporating graphene-carboxyl nanosheets (1, 2, and 3 wt%) within the optimized scaffold with 2 wt% polypyrrole was thoroughly studied. The electrical conductivity of the hydrogels was significantly enhanced from 0.0615 ± 0.007 S/cm in GelMA/alginate to 0.124 ± 0.04 S/cm with the addition of 5 wt% polypyrrole. Also, 3 wt% carboxyl graphene improved the electrical conductivity to 0.27 ± 0.09 S/cm. The compressive strength of carboxyl-graphene-containing hydrogel was in the range of 175 to 520 kPa, and tensile strength was 61 and 133 kPa. The simplicity and low-cost fabrication, tunable mechanical properties, optimal electrical conductivity, blood compatibility, and non-cytotoxicity of GelMA/alginate/polypyrrole/graphene biocomposite hydrogel is a promising construct for cardiac tissue engineering.

Magnetic Graphene Oxide Nanocomposites for Selective miRNA Separation and Recovery

In this study, we developed magnetic graphene oxide composites by chemically attaching Fe3O4 nanoparticles to graphene oxide nanosheets. Characterization techniques, including Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), Raman spectroscopy, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and transmission electron microscopy (TEM), confirmed the successful synthesis of Fe3O4@GO composites with desirable properties. The resulting composites exhibited superparamagnetic behavior, solubility, and compatibility for efficient miRNA separation. Using miR-29a as a model, we demonstrated the effective binding of miR-29a to the magnetic graphene oxide (GO) composites at an optimal concentration of 1.5 mg/mL, followed by a simple separation using magnetic forces. Additionally, the addition of 5.0 M urea enhanced the miRNA recovery. These findings highlight the potential use of our magnetic graphene oxide composites for the efficient separation and recovery of miR-29a, suggesting their broad applicability in various miRNA-based studies. Further exploration can focus on investigating endogenous miRNAs with aberrant expression patterns, contributing to the advancements in precision medicine.

A study on the therapeutic potential of graphene titanate nanocomposite for treating chemically induced arthritis in rats

Nanotechnology holds substantial promise in the innovative therapies for rheumatoid arthritis (RA). The current study was designed to synthesize and characterize a new graphene titanate nanocomposite (GTNc) and explore its anti-arthritic, anti-inflammatory, and antioxidant potencies against Complete Freund's adjuvant (CFA)-induced arthritis in rats, as well as investigate the underlying molecular mechanisms. Our characterization methods included XRD, FT-IR, SEM, EDX, zeta potential, practical size, and XRF to characterize the novel GTNc. Our findings revealed that arthritic rats treated with GTNc exhibited lower levels of RF, CRP, IL-1β, TNF-α, IL-17, and ADAMTS-5, and higher levels of IL-4 and TIMP-3. In arthritic rats, GTNc reduced LPO levels while increasing GSH content and GST antioxidant activity. Additionally, GTNc decreased the expression of the TGF-β mRNA gene in arthritic rats. Histopathological investigation showed that GTNc reduced inflammatory cell infiltration, cartilage degradation, and bone destruction in joint injuries caused by CFA in the arthritic rats. Collectively, the anti-arthritic, anti-inflammatory, and antioxidant properties of GTNc appear promising for future arthritis treatments and bone disability research.

Physico-mechanical and antimicrobial properties of an elastomeric ligature coated with reduced nanographene oxide-nano curcumin subjected to dual-modal photodynamic and photothermal inactivation against Streptococcus mutans biofilms

BACKGROUND

White spot lesions (WSLs) are a common side effect of fixed orthodontic treatment. Streptococcus mutans is the primary causative agent of WSLs and dental caries on the teeth during treatment. According to the unique features of reduced graphene oxide-nano curcumin (rGO-nCur), this study aimed to investigate the mechanical properties and antimicrobial potency of rGO-nCur coated orthodontic elastomeric ligatures as a novel coating composite following dual-modal photodynamic inactivation (PDI) and photothermal inactivation (PTI) against S. mutans biofilms.

METHODS

After confirmation of rGO-nCur synthesis and coating elastomeric ligatures with different concentration levels of 1.25, 2.5, 5, 7.5, and 10 % of rGO-nCur, tensile strength, force decay, extension to tensile strength, and contact angle of the coated elastomeric ligatures were measured using universal testing machine and sessile drop method, respectively. To investigate the mechanism through which irradiated rGO-nCur can inhibit the formation of S. mutans biofilms, intracellular reactive oxygen species (ROS) generation, and increase in temperature of rGO-nCur solutions under the 450 and 980 nm laser irradiation, respectively, were measured. The anti-biofilm activity and inhibition of water-insoluble extracellular polysaccharide (EPS) production ability of irradiated rGO-nCur coated elastomeric ligatures using a 450 nm diode laser (195 J/cm2), a 980 nm diode laser (195 J/cm2), and a combination of both (78 J/cm2 of irradiation from each one) (i.e., PDI, PTI, and dual-modal PDI/PTI, respectively) were determined. Also, the expression of virulence genes involved in biofilm formation (comDE, gtfD, and smuT) was assessed by quantitative real-time polymerase chain reaction (RT-qPCR) following the mentioned treatment. One-way ANOVA test and Tukey post-hoc test at a p-value equal to/or less than 0.05 were used to analyze the obtained data.

RESULTS

The synthesis of GO nano-sheets in a layered structure with a thickness of 0.76 nm was confirmed by AFM analysis. FESEM showed that the exfoliated sheet of synthesized GO had several micrometers in lateral size. DLS revealed that the mean particle size and density index of synthesized nCur were 57.47 ± 2.14 nm and 10 % respectively. In DLS analysis, rGO-nCur showed more positive surface charge (24 mV) than the nano-sheets of GO. FESEM confirmed the coating of rGO-nCur on elastomeric ligatures. ANOVA revealed that tensile strength of 1.25, 2.5, and 5 % rGO-nCur coated elastomeric ligatures were not decreased statistically significantly (P > 0.05). Mean tensile strength and recorded force of 7.5 and 10 % rGO-nCur coated elastomeric ligatures decreased significantly after 14 days' immersion in the artificial saliva (P < 0.05). On the 28th day of the study, the mean of the tensile strength of elastomeric ligatures coated with 10 % rGO-nCur (13.03 ± 0.10 N) was recorded as 55.90 % of the initial tensile strength (23.31 ± 0.41 N in uncoated elastomeric ligatures), while the mean tensile strength of elastomeric ligatures coated with 7.5 % rGO-nCur (16.01 ± 0.10 N) was measured as 68.94 % of the initial tensile strength (23.22 ± 0.09 N in uncoated elastomeric ligatures). When comparing the coated elastomeric ligatures at 7.5 % and 10 % to the original uncoated elastomeric ligatures at similar time intervals, statistically significant decreases in extension to tensile strength (0.42 to 0.71 mm or 3.02 to 5.05 %; all P < 0.05) were observed. The largest contact angle was measured in elastomeric ligatures coated by 10 % rGO-nCur followed by 7.5 and 5 % rGO-nCur (128 ± 2.19°, 117 ± 2.23°, and 99 ± 1.83°; respectively). The results revealed a rise of 6.4-fold in intracellular ROS and an 11.2 °C increase in the temperature of rGO-nCur solutions following the 450 nm and 980 nm laser irradiation, respectively. The 5 % rGO-nCur coated elastomeric ligature mediated dual-modal PDI/PTI showed the most inhibition of the biofilm formation of S. mutans by 83.62 % (P = 0.00). Significant reductions in water-insoluble EPS were detected in biofilm cultures of S. mutans on 1.25 % rGO-nCur coated elastomeric ligatures following irradiation with dual waves of the 450 nm and 980 nm diode lasers (i.e., dual-modal PDI/PTI; 96.17 %; P = 0.00). The expression levels of comDE, gtfD, and smuT virulence genes were significantly downregulated (7.52-, 13.92-, and 8.23-fold, respectively) in the biofilm cultures of S. mutans on 1.25 % rGO-nCur coated elastomeric ligatures following dual-modal PDI/PTI in comparison with biofilm cultures on non-coated elastomeric ligatures.

CONCLUSION

5 % rGO-nCur coated elastomeric ligatures following irradiation with dual waves of the 450 and 980 nm diode lasers (dual-modal PDI/PTI), without adverse effects on the physico-mechanical properties of elastomeric ligatures, can be used to inhibit the formation of S. mutans biofilms on the coated elastomeric ligatures around orthodontic brackets.

Graphene-based biosensors for detecting coronavirus: a brief review

The coronavirus (SARS-CoV-2) disease has affected the globe with 770 437 327 confirmed cases, including about 6 956 900 deaths, according to the World Health Organization (WHO) as of September 2023. Hence, it is imperative to develop diagnostic technologies, such as a rapid cost-effective SARS-CoV-2 detection method. A typical biosensor enables biomolecule detection with an appropriate transducer by generating a measurable signal from the sample. Graphene can be employed as a component for ultrasensitive and selective biosensors based on its physical, optical, and electrochemical properties. Herein, we briefly review graphene-based electrochemical, field-effect transistor (FET), and surface plasmon biosensors for detecting the SARS-CoV-2 target. In addition, details on the surface modification, immobilization, sensitivity and limit of detection (LOD) of all three sensors with regard to SARS-CoV-2 were reported. Finally, the point-of-care (POC) detection of SARS-CoV-2 using a portable smartphone and a wearable watch is a current topic of interest.

Graphene oxide nanoarchitectures in cancer therapy: Drug and gene delivery, phototherapy, immunotherapy, and vaccine development

The latest advancements in oncology involves the creation of multifunctional nanostructures. The integration of nanoparticles into the realm of cancer therapy has brought about a transformative shift, revolutionizing the approach to addressing existing challenges and limitations in tumor elimination. This is particularly crucial in combating the emergence of resistance, which has significantly undermined the effectiveness of treatments like chemotherapy and radiotherapy. GO stands as a carbon-derived nanoparticle that is increasingly finding utility across diverse domains, notably in the realm of biomedicine. The utilization of GO nanostructures holds promise in the arena of oncology, enabling precise transportation of drugs and genetic material to targeted sites. GO nanomaterials offer the opportunity to enhance the pharmacokinetic behavior and bioavailability of drugs, with documented instances of these nanocarriers elevating drug accumulation at the tumor location. The GO nanostructures encapsulate genes, shielding them from degradation and facilitating their uptake within cancer cells, thereby promoting efficient gene silencing. The capability of GO to facilitate phototherapy has led to notable advancements in reducing tumor progression. By PDT and PTT combination, GO nanomaterials hold the capacity to diminish tumorigenesis. GO nanomaterials have the potential to trigger both cellular and innate immunity, making them promising contenders for vaccine development. Additionally, types of GO nanoparticles that respond to specific stimuli have been applied in cancer eradication, as well as for the purpose of cancer detection and biomarker diagnosis. Endocytosis serves as the mechanism through which GO nanomaterials are internalized. Given these advantages, the utilization of GO nanomaterials for tumor elimination comes highly recommended.

A Graphene Oxide-based Assay for Sensitive Osteonecrosis of the Femoral Head (ONFH) related microRNA Detection via Exonuclease-III Assisted Dual Signal Cycle

Accurate detection of circulating microRNAs (miRNAs) plays a vital role in the diagnosis of various diseases. The current miRNA detection methods, however, are widely criticized for their low sensitivity and excessive background signal. Herein, we propose a graphene oxide (GO) based fluorescent biosensor for sensitive and reliable miRNA analysis with a low background signal by utilizing exonuclease III (Exo III)-assisted target recycling and hybridization chain reaction (HCR). To initiate Exo-III-assisted dual signal cycles, a hairpin DNA probe (H probe) was developed for selective miRNA binding. Dye quenching occurred when carboxyfluorescein (FAM)-labeled hairpins (HP1 and HP1) were unable to bind to their intended target and instead adsorb onto the surface of GO via p-stacking interactions. Exo III sequentially cleaved the 3'-strand of the H probe and the S probe upon attachment of the target miRNA, resulting in the release of the miRNA and the autonomous production of a "g" sequence. The released target miRNA then hybridized with a second H probe and progressed to the subsequent reaction phase. With the help of the HP1 and HP2 probes, a lengthy dsDNA product was produced when the "g" sequence triggered HCR. The dsDNA product was not absorbed by GO, and the material instead fluoresced brightly. As a result, the amount of miRNA of interest was measured. With a LOD of only 5.6 fM, this bioassay demonstrated excellent selectivity and great sensitivity.

Surface engineering of two-dimensional hexagonal boron-nitride for optoelectronic devices

Two-dimensional hexagonal boron nitride (2D h-BN) is being extensively studied in optoelectronic devices due to its electronic and photonic properties. However, the controlled optimization of h-BN's insulating properties is necessary to fully explore its potential in energy conversion and storage devices. In this work, we engineered the surface of h-BN nanoflakes via one-step in situ chemical functionalization using a liquid-phase exfoliation approach. The functionalized h-BN (F-h-BN) nanoflakes were subsequently dispersed on the surface of TiO2 to tune the TiO2/QDs interface of the optoelectronic device. The photoelectrochemical (PEC) devices based on TiO2/F-h-BN/QDs with optimized addition of carbon nanotubes (CNTs) and scattering layers showed 46% improvement compared to the control device (TiO2/QDs). This significant improvement is attributed to the reduced trap/carrier recombination and enhanced carrier injection rate of the TiO2-CNTs/F-h-BN/QDs photoanode. Furthermore, by employing an optimized TiO2-CNTs/F-h-BN/QDs photoanode, QDs-sensitized solar cells (QDSCs) yield an 18% improvement in photoconversion efficiency. This represents a potential and adaptability of our approach, and pathway to explore surface-engineered 2D materials to optimize the interface of solar energy conversion and other emerging optoelectronic devices.

Impedimetric aptasensor based on MOF based composite for measuring of carcinoembryonic antigen as a tumor biomarker

In this research, gold nanoparticle (GNPs)-modified metal-organic framework/reduced graphene oxide (MOF(801)/rGO) hybrid was employed to design a new aptasensor for carcinoembryonic antigen (CEA) quantification in biological sample. The sensing ability of the electrode for CEA biomarker was examined with electrochemical impedance spectroscopy (EIS) and cyclic voltammetry procedures. Besides, CEA was electrochemically quantified by the EIS method. With respect to the high surface-to-volume ratio of MOF(801) and the good electron transfer ability of rGO, the proposed sensor displayed notable sensitivity and reliability in the CEA analysis. The derived electrode showed an appreciable detection limit of 0.8 pg L-1 using EIS protocol. In addition, the present aptasensor revealed diverse advantages including anti-interference property, wide linear range (0.0025-0.25 ng L-1), convenience and high efficiency toward CEA quantification. More importantly, the performance of the suggested assay remains unchanged in analysis of CEA in body fluids. The established assay demonstrates that the suggested biosensor is a promising device in clinical diagnosis.

Inhibitory effect of plain and functionalized graphene nanoplateles on hen egg white lysozyme fibrillation

Protein fibrillation is a phenomenon associated with misfolding and the production of highly ordered nanofibrils, which may cause serious degenerative diseases such as Parkinson's disease, Alzheimer's disease, and type 2 diabetes. Upon contact with biological fluids, the nanomaterials are immediately covered by proteins and interact with them. In this study, the effects of Graphene NanoPlateles (Plain-GNPs) and their modified forms with a carboxyl group (GNPs -COOH) and an amine group (GNPs -NH2) are evaluated on the fibrillation process of Hen Egg White Lysozyme (HEWL). The fibrillation process of HEWL was studied using thioflavin-T, Circular Dichroism spectrometry, and Atomic Force Microscopy. Plain-GNPs significantly decreased the fibrillation process at different stages, including nucleation, exponential fibrillation phases, and end-mature fibril products. However, GNPs-COOH and GNPs-NH2 affected the final fluorescence of ThT. The species formed in the presence of Plain-GNPs showed less toxicity in SH-SY5Y cells, which could be applicable for therapeutic purposes.

Influence of GO-Antisense miRNA-21 on the Expression of Selected Cytokines at Glioblastoma Cell Lines

Introduction

Graphene oxide (GO) is a single layer of carbon atoms with unique properties, which are beneficial due to its surface functionalisation by miRNA. miRNAs are a non-coding small form of RNA that suppress the expression of protein-coding genes by translational repression or degradation of messenger RNA. Antisense miRNA-21 is very promising for future investigation in cancer therapy. This study aimed to detect cytokine expression levels after the administration of GO-antisense miRNA-21 into U87, U118, U251 and T98 glioma cell lines.

Methods

U87, U118, U251 and T98 glioma cell line were investigated in term of viability, human cytokine expression level at protein and genes after treatment with GO, GO-antisense miRNA-21 and antisense miRNA-21. The delivery of antisense miRNA-21 into the glioma cell at in vitro investigation were conducted by GO based transfection and electroporation.

Results

The results of the protein microarray and gene expression profile showed that complexes of GO-antisense miRNA-21 modified the metallopeptidase inhibitor 2 (TIMP-2), interleukin-6 (IL-6), interleukin 8 (IL-8), intercellular adhesion molecule 1 (ICAM-1), and monocyte chemoattractant protein-1 (MCP-1) expression level compared to transfection by electroporation of antisense miRNA-21 at investigated glioblastoma cell lines. The TIMP-2 protein and gene expression level was upregulated after antisense miRNA-21 delivery by GO complex into U87, U251 and T98 glioblastoma cell lines comparing to the non-treated control group. The downregulation at protein expression level of ICAM - 1 was observed at U87, U118, U251 and T98 glioma cell lines. Moreover, the IL-8 expression level at mRNA for genes and protein was decreased significantly after delivery the antisense-miRNA-21 by GO compared to electroporation as a transfection method.

Discussion

This work demonstrated that the graphene oxide complexes with antisense miRNA-21 can effectively modulate the cytokine mRNA and protein expression level at U87, U118, U251 and T98 glioma cell lines.

Development of metal free carbon catalyst derived from Parthenium hysterophorus for the electrochemical detection of dopamine

Parthenium hysterophorus, one of the seven most hazardous weeds is widely known for its allergic, respiratory and skin-related disorders. It is also known to affect biodiversity and ecology. For eradication of the weed, its effective utilization for the successful synthesis of carbon-based nanomaterial is a potent management strategy. In this study, reduced graphene oxide (rGO) was synthesized from weed leaf extract through a hydrothermal-assisted carbonization method. The crystallinity and geometry of the as-synthesized nanostructure are confirmed from the X-ray diffraction study, while the chemical architecture of the nanomaterial is ascertained through X-ray photoelectron spectroscopy. The stacking of flat graphene-like layers with a size range of ∼200-300 nm is visualized through high-resolution transmission electron microscopy images. Further, the as-synthesized carbon nanomaterial is advanced as an effective and highly sensitive electrochemical biosensor for dopamine, a vital neurotransmitter of the human brain. Nanomaterial oxidizes dopamine at a much lower potential (0.13 V) than other metal-based nanocomposites. Moreover, the obtained sensitivity (13.75 and 3.31 μA μM-1 cm-2), detection limit (0.6 and 0.8 μM), the limit of quantification (2.2 and 2.7 μM) and reproducibility calculated through cyclic voltammetry/differential pulse voltammetry respectively outcompete many metal-based nanocomposites that were previously used for the sensing of dopamine. This study boosts the research on the metal-free carbon-based nanomaterial derived from waste plant biomass.

The influence of protein corona on Graphene Oxide: implications for biomedical theranostics

Graphene-based nanomaterials have attracted significant attention in the field of nanomedicine due to their unique atomic arrangement which allows for manifold applications. However, their inherent high hydrophobicity poses challenges in biological systems, thereby limiting their usage in biomedical areas. To address this limitation, one approach involves introducing oxygen functional groups on graphene surfaces, resulting in the formation of graphene oxide (GO). This modification enables improved dispersion, enhanced stability, reduced toxicity, and tunable surface properties. In this review, we aim to explore the interactions between GO and the biological fluids in the context of theranostics, shedding light on the formation of the "protein corona" (PC) i.e., the protein-enriched layer that formed around nanosystems when exposed to blood. The presence of the PC alters the surface properties and biological identity of GO, thus influencing its behavior and performance in various applications. By investigating this phenomenon, we gain insights into the bio-nano interactions that occur and their biological implications for different intents such as nucleic acid and drug delivery, active cell targeting, and modulation of cell signalling pathways. Additionally, we discuss diagnostic applications utilizing biocoronated GO and personalized PC analysis, with a particular focus on the detection of cancer biomarkers. By exploring these cutting-edge advancements, this comprehensive review provides valuable insights into the rapidly evolving field of GO-based nanomedicine for theranostic applications.

Label-Free DNA Biosensor Based on Reduced Graphene Oxide and Gold Nanoparticles

Currently available DNA detection techniques frequently require compromises between simplicity, speed, accuracy, and cost. Here, we propose a simple, label-free, and cost-effective DNA detection platform developed at screen-printed carbon electrodes (SPCEs) modified with reduced graphene oxide (RGO) and gold nanoparticles (AuNPs). The preparation of the detection platform involved a two-step electrochemical procedure based on GO reduction onto SPCEs followed by the electrochemical reduction of HAuCl4 to facilitate the post-grafting reaction with AuNPs. The final sensor was fabricated by the simple physical adsorption of a single-stranded DNA (ssDNA) probe onto a AuNPs-RGO/SPCE electrode. Each preparation step was confirmed by morphological and structural characterization using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy, respectively. Furthermore, the electrochemical properties of the modified electrodes have been investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results demonstrated that the introduction of AuNPs onto RGO/SPCEs led to an enhancement in surface conductivity, a characteristic that favored an increased sensitivity in detection. The detection process relied on the change in the electrochemical signal induced by the binding of target DNA to the bioreceptor and was particularly monitored by the change in the charge transfer resistance of a [Fe(CN)6]4-/3- redox couple added in the test solution.

Recent Developments in Two-Dimensional Materials-Based Membranes for Oil-Water Separation

The industrialization witnessed in the last century has resulted in an unprecedented increase in water pollution. In particular, the water pollution induced by oil contaminants from oil spill accidents, as well as discharges from pharmaceutical, oil/gas, and metal processing industries, have raised concerns due to their potential to pose irreversible threats to the ecosystems. Therefore, the effective treating of these large volumes of oily wastewater is an inevitable challenge to address. Separating oil-water mixtures by membranes has been an attractive technology due to the high oil removal efficiency and low energy consumption. However, conventional oil-water separation membranes may not meet the complex requirements for the sustainable treatment of wastewater due to their relatively shorter life cycle, lower chemical and thermal stability, and permeability/selectivity trade-off. Recent advancements in two-dimensional (2D) materials have provided opportunities to address these challenges. In this article, we provide a brief review of the most recent advancements in oil-water separation membranes modified with 2D materials, with a focus on MXenes, graphenes, metal-organic frameworks, and covalent organic frameworks. The review briefly covers the backgrounds, concepts, fabrication methods, and the most recent representative studies. Finally, the review concludes by describing the challenges and future research directions.

Intrinsic mechanisms for the inhibition effect of graphene oxide on the catalysis activity of alpha amylase

Comprehending the interactions between graphene oxide (GO) and enzymes is critical for understanding the toxicities of GO. In this study, the inherent interactions of GO with α-amylase as a typical enzyme, and the impacts of GO on the conformation and biological activities of α-amylase were systematically investigated. The results reveal that GO formed ground-state complex with α-amylase primarily via hydrogen bonding and van der Waals interactions, thus quenching the intrinsic fluorescence of the protein statically. Particularly, the strong interactions altered the microenvironment of tyrosine and tryptophan residues, caused rearrangement of polypeptide structure, and reduced the contents of α-helices and β-sheets, thus changing the conformational structure of α-amylase. According to molecular docking results, GO binds with the amino acid residues (i.e., His299, Asp300, and His305) of α-amylase mainly through hydrogen bonding, which is in accordance with in vitro incubation experiments. As a consequence, the ability of α-amylase to catalyze starch hydrolysis into glucose was depressed by GO, suggesting that GO might cause dysfunction of α-amylase. This study discloses the intrinsic binding mechanisms of GO with α-amylase and provides novel insights into the adverse effects of GO as it enters organisms.

The mechanical, optical, and thermal properties of graphene influencing its pre-clinical use in treating neurological diseases

Rapid progress in nanotechnology has advanced fundamental neuroscience and innovative treatment using combined diagnostic and therapeutic applications. The atomic scale tunability of nanomaterials, which can interact with biological systems, has attracted interest in emerging multidisciplinary fields. Graphene, a two-dimensional nanocarbon, has gained increasing attention in neuroscience due to its unique honeycomb structure and functional properties. Hydrophobic planar sheets of graphene can be effectively loaded with aromatic molecules to produce a defect-free and stable dispersion. The optical and thermal properties of graphene make it suitable for biosensing and bioimaging applications. In addition, graphene and its derivatives functionalized with tailored bioactive molecules can cross the blood-brain barrier for drug delivery, substantially improving their biological property. Therefore, graphene-based materials have promising potential for possible application in neuroscience. Herein, we aimed to summarize the important properties of graphene materials required for their application in neuroscience, the interaction between graphene-based materials and various cells in the central and peripheral nervous systems, and their potential clinical applications in recording electrodes, drug delivery, treatment, and as nerve scaffolds for neurological diseases. Finally, we offer insights into the prospects and limitations to aid graphene development in neuroscience research and nanotherapeutics that can be used clinically.

In vitro safety assessment of reduced graphene oxide in human monocytes and T cells

Considering the increase in the use of graphene derivatives in different fields, the environmental and human exposure to these materials is likely, and the potential consequences are not fully elucidated. This study is focused on the human immune system, as this plays a key role in the organism's homeostasis. In this sense, the cytotoxicity response of reduced graphene oxide (rGO) was investigated in monocytes (THP-1) and human T cells (Jurkat). A mean effective concentration (EC₅₀-24 h) of 121.45 ± 11.39 μg/mL and 207.51 ± 21.67 μg/mL for cytotoxicity was obtained in THP-1 and Jurkat cells, respectively. rGO decreased THP-1 monocytes differentiation at the highest concentration after 48 h of exposure. Regarding the inflammatory response at genetic level, rGO upregulated IL-6 in THP-1 and all cytokines tested in Jurkat cells after 4 h of exposure. At 24 h, IL-6 upregulation was maintained, and a significant decrease of TNF-α gene expression was observed in THP-1 cells. Moreover, TNF-α, and INF-γ upregulation were maintained in Jurkat cells. With respect to the apoptosis/necrosis, gene expression was not altered in THP-1 cells, but a down regulation of BAX and BCL-2 was observed in Jurkat cells after 4 h of exposure. These genes showed values closer to negative control after 24 h. Finally, rGO did not trigger a significant release of any cytokine at any exposure time assayed. In conclusion, our data contributes to the risk assessment of this material and suggest that rGO has an impact on the immune system whose final consequences should be further investigated.

Interaction of Graphene Oxide Nanoparticles with Human Mesenchymal Stem Cells Visualized in the Cell-IQ System

Graphene oxide is a promising nanomaterial with many potential applications. However, before it can be widely used in areas such as drug delivery and medical diagnostics, its influence on various cell populations in the human body must be studied to ensure its safety. We investigated the interaction of graphene oxide (GO) nanoparticles with human mesenchymal stem cells (hMSCs) in the Cell-IQ system, evaluating cell viability, mobility, and growth rate. GO nanoparticles of different sizes coated with linear or branched polyethylene glycol (P or bP, respectively) were used at concentrations of 5 and 25 μg/mL. Designations were the following: P-GOs (Ø 184 ± 73 nm), bP-GOs (Ø 287 ± 52 nm), P-GOb (Ø 569 ± 14 nm), and bP-GOb (Ø 1376 ± 48 nm). After incubating the cells with all types of nanoparticles for 24 h, the internalization of the nanoparticles by the cells was observed. We found that all GO nanoparticles used in this study exerted a cytotoxic effect on hMSCs when used at a high concentration (25 μg/mL), whereas at a low concentration (5 μg/mL) a cytotoxic effect was observed only for bP-GOb particles. We also found that P-GOs particles decreased cell mobility at a concentration of 25 μg/mL, whereas bP-GOb particles increased it. Larger particles (P-GOb and bP-GOb) increased the rate of movement of hMSCs regardless of concentration. There were no statistically significant differences in the growth rate of cells compared with the control group.

Enantioseparation/Recognition based on nano techniques/materials

Enantiomers show different behaviors in interaction with the chiral environment. Due to their identical chemical structure and their wide application in various industries, such as agriculture, medicine, pesticide, food, and so forth, their separation is of great importance. Today, the term "nano" is frequently encountered in all fields. Technology and measuring devices are moving towards miniaturization, and the usage of nanomaterials in all sectors is expanding substantially. Given that scientists have recently attempted to apply miniaturized techniques known as nano-liquid chromatography/capillary-liquid chromatography, which were originally accomplished in 1988, as well as the widespread usage of nanomaterials for chiral resolution (back in 1989), this comprehensive study was developed. Searching the terms "nano" and "enantiomer separation" on scientific websites such as Scopus, Google Scholar, and Web of Science yields articles that either use miniaturized instruments or apply nanomaterials as chiral selectors with a variety of chemical and electrochemical detection techniques, which are discussed in this article.

Isolation of organophosphate pesticides from water using gold nanoparticles doped magnetic three-dimensional graphene oxide

Pesticides are a large group of pristine organic contaminants, which are widely discharged into environmental water due to agricultural activities. Hence, extraction, determination, and removal of pesticides from water resources are necessary for human health. In this study, novel adsorbent was developed based on three-dimensional magnetic graphene coated with gold nanoparticles (3D-MG@AuNPs) for extraction of chlorpyrifos, dicrotophos, fenitrothion, and piperophos as four specific organophosphorus pesticides (OPPs) from wastewater and tap water samples. The proposed nanocomposite was characterized; FTIR and EDX are performed for the expected functional groups and elemental analysis, SEM showed the unique and spherical AuNPs are well dispersed over graphene sheets. In this investigation, the important parameters that have effect on the extraction efficiency, including the desorbing solvent, desorbing solvent volume, vortex time, the extraction time, adsorbent dosage, pH of sample solutions, and salt effect were evaluated. In conclusion, the measured amounts of the chosen OPPs were determined using the gas chromatography microelectron capture (μECD-GC) method. Limits of quantification (S/N ratio of 10) and detection (S/N ratio of 3) were attained at concentrations of 0.26-0.43 μg.L^-1 and 0.08-0.14 μg.L^-1, respectively. According to the results of the investigations, the synthesized 3D-MG@AuNPs did not require any complicated sample preparation methods; therefore, it is a very good choice for solid magnetic phase extraction studies.

Contemporary updates on bioremediation applications of graphene and its composites

Graphene, a 2D single-layered carbon sp² hybrid substance set in a honeycomb network, is widespread in many carbon-based materials. Due to its extraordinary optical, electrical, thermal, mechanical, and magnetic competences as well as its significant specific surface area, it has attracted a lot of interest recently. Synthesizing graphene refers to any process for creating or extracting the material, depending on the desired purity, size, and efflorescence of the finished good. Numerous methods have been employed for graphene synthesis categorized as top-down procedures and bottom-up procedures. Graphene finds its implementations in various industries such as electronics, energy, chemical, transport, defence, and biomedical areas such as accurate biosensing. It has been widely used in water treatment as a binder for organic contaminants and heavy metals. Many researches have fixated on creating various modified graphene, graphene oxide composites, graphene nanoparticle composites and semiconductor hybrids of graphene for contaminant removal from water. In this review, we have tried to address various production methods for graphene and its composites along with their advantages and disadvantages. Furthermore, we have presented a summary on graphene's outstanding immobilization of a variety of contaminants like toxic heavy metals, organic dyes, inorganic pollutants and pharmaceutical wastes. Additionally, a development of graphene-based microbial fuel cell (MFC) has been evaluated in an effort to produce ecological wastewater treatment and bioelectricity.

Polymer/Graphene Nanocomposites via 3D and 4D Printing—Design and Technical Potential

Graphene is an important nanocarbon nanofiller for polymeric matrices. The polymer–graphene nanocomposites, obtained through facile fabrication methods, possess significant electrical–thermal–mechanical and physical properties for technical purposes. To overcome challenges of polymer–graphene nanocomposite processing and high performance, advanced fabrication strategies have been applied to design the next-generation materials–devices. This revolutionary review basically offers a fundamental sketch of graphene, polymer–graphene nanocomposite and three-dimensional (3D) and four-dimensional (4D) printing techniques. The main focus of the article is to portray the impact of 3D and 4D printing techniques in the field of polymer–graphene nanocomposites. Polymeric matrices, such as polyamide, polycaprolactone, polyethylene, poly(lactic acid), etc. with graphene, have been processed using 3D or 4D printing technologies. The 3D and 4D printing employ various cutting-edge processes and offer engineering opportunities to meet the manufacturing demands of the nanomaterials. The 3D printing methods used for graphene nanocomposites include direct ink writing, selective laser sintering, stereolithography, fused deposition modeling and other approaches. Thermally stable poly(lactic acid)–graphene oxide nanocomposites have been processed using a direct ink printing technique. The 3D-printed poly(methyl methacrylate)–graphene have been printed using stereolithography and additive manufacturing techniques. The printed poly(methyl methacrylate)–graphene nanocomposites revealed enhanced morphological, mechanical and biological properties. The polyethylene–graphene nanocomposites processed by fused diffusion modeling have superior thermal conductivity, strength, modulus and radiation- shielding features. The poly(lactic acid)–graphene nanocomposites have been processed using a number of 3D printing approaches, including fused deposition modeling, stereolithography, etc., resulting in unique honeycomb morphology, high surface temperature, surface resistivity, glass transition temperature and linear thermal coefficient. The 4D printing has been applied on acrylonitrile-butadiene-styrene, poly(lactic acid) and thermosetting matrices with graphene nanofiller. Stereolithography-based 4D-printed polymer–graphene nanomaterials have revealed complex shape-changing nanostructures having high resolution. These materials have high temperature stability and high performance for technical applications. Consequently, the 3D- or 4D-printed polymer–graphene nanocomposites revealed technical applications in high temperature relevance, photovoltaics, sensing, energy storage and other technical fields. In short, this paper has reviewed the background of 3D and 4D printing, graphene-based nanocomposite fabrication using 3D–4D printing, development in printing technologies and applications of 3D–4D printing.

Sustainable Nanomaterials for Biomedical Applications

Significant progress in nanotechnology has enormously contributed to the design and development of innovative products that have transformed societal challenges related to energy, information technology, the environment, and health. A large portion of the nanomaterials developed for such applications is currently highly dependent on energy-intensive manufacturing processes and non-renewable resources. In addition, there is a considerable lag between the rapid growth in the innovation/discovery of such unsustainable nanomaterials and their effects on the environment, human health, and climate in the long term. Therefore, there is an urgent need to design nanomaterials sustainably using renewable and natural resources with minimal impact on society. Integrating sustainability with nanotechnology can support the manufacturing of sustainable nanomaterials with optimized performance. This short review discusses challenges and a framework for designing high-performance sustainable nanomaterials. We briefly summarize the recent advances in producing sustainable nanomaterials from sustainable and natural resources and their use for various biomedical applications such as biosensing, bioimaging, drug delivery, and tissue engineering. Additionally, we provide future perspectives into the design guidelines for fabricating high-performance sustainable nanomaterials for medical applications.

Nanostructured supports for multienzyme co-immobilization for biotechnological applications: Achievements, challenges and prospects

The synergistic combination of current biotechnological and nanotechnological research has turned to multienzyme co-immobilization as a promising concept to design biocatalysis engineering. It has also intensified the development and deployment of multipurpose biocatalysts, for instance, multienzyme co-immobilized constructs, via biocatalysis/protein engineering to scale-up and fulfil the ever-increasing industrial demands. Considering the characteristic features of both the loaded multienzymes and nanostructure carriers, i.e., selectivity, specificity, stability, resistivity, induce activity, reaction efficacy, multi-usability, high catalytic turnover, optimal yield, ease in recovery, and cost-effectiveness, multienzyme-based green biocatalysts have become a powerful norm in biocatalysis/protein engineering sectors. In this context, the current state-of-the-art in enzyme engineering with a synergistic combination of nanotechnology, at large, and nanomaterials, in particular, are significantly contributing and providing robust tools to engineer and/or tailor enzymes to fulfil the growing catalytic and contemporary industrial needs. Considering the above critics and unique structural, physicochemical, and functional attributes, herein, we spotlight important aspects spanning across prospective nano-carriers for multienzyme co-immobilization. Further, this work comprehensively discuss the current advances in deploying multienzyme-based cascade reactions in numerous sectors, including environmental remediation and protection, drug delivery systems (DDS), biofuel cells development and energy production, bio-electroanalytical devices (biosensors), therapeutical, nutraceutical, cosmeceutical, and pharmaceutical oriented applications. In conclusion, the continuous developments in nano-assembling the multienzyme loaded co-immobilized nanostructure carriers would be a unique way that could act as a core of modern biotechnological research.

Bioactive Materials for Caries Management: A Literature Review

Researchers have developed novel bioactive materials for caries management. Many clinicians also favour these materials, which fit their contemporary practice philosophy of using the medical model of caries management and minimally invasive dentistry. Although there is no consensus on the definition of bioactive materials, bioactive materials in cariology are generally considered to be those that can form hydroxyapatite crystals on the tooth surface. Common bioactive materials include fluoride-based materials, calcium- and phosphate-based materials, graphene-based materials, metal and metal-oxide nanomaterials and peptide-based materials. Silver diamine fluoride (SDF) is a fluoride-based material containing silver; silver is antibacterial and fluoride promotes remineralisation. Casein phosphopeptide-amorphous calcium phosphate is a calcium- and phosphate-based material that can be added to toothpaste and chewing gum for caries prevention. Researchers use graphene-based materials and metal or metal-oxide nanomaterials as anticaries agents. Graphene-based materials, such as graphene oxide-silver, have antibacterial and mineralising properties. Metal and metal-oxide nanomaterials, such as silver and copper oxide, are antimicrobial. Incorporating mineralising materials could introduce remineralising properties to metallic nanoparticles. Researchers have also developed antimicrobial peptides with mineralising properties for caries prevention. The purpose of this literature review is to provide an overview of current bioactive materials for caries management.

Graphene-based nanomaterials for stimuli-sensitive controlled delivery of therapeutic molecules

Stimuli-responsive drug delivery has attracted tremendous attention in the past decades. It provides a spatial- and temporal-controlled release in response to different triggers, thus enabling highly efficient drug delivery and minimizing drug side effects. Graphene-based nanomaterials have been broadly explored, and they show great potential in smart drug delivery due to their stimuli-responsive behavior and high loading capacity for an extended range of drug molecules. These characteristics are a result of high surface area, mechanical stability and chemical stability, and excellent optical, electrical, and thermal properties. Their great and infinite functionalization potential also allows them to be integrated into several types of polymers, macromolecules, or other nanoparticles, leading to the fabrication of novel nanocarriers with enhanced biocompatibility and trigger-sensitive properties. Thus, numerous studies have been dedicated to graphene modification and functionalization. In the current review, we introduce graphene derivatives and different graphene-based nanomaterials utilized in drug delivery and discuss the most important advances in their functionalization and modification. Also, their potential and progress in an intelligent drug release in response to different types of stimuli either endogenous (pH, redox conditions, and reactive oxygen species (ROS)) or exogenous (temperature, near-infrared (NIR) radiation, and electric field) will be debated.

Designing multifunctional biocatalytic cascade system by multi-enzyme co-immobilization on biopolymers and nanostructured materials

In recent decades, enzyme-based biocatalytic systems have garnered increasing interest in industrial and applied research for catalysis and organic chemistry. Many enzymatic reactions have been applied to sustainable and environmentally friendly production processes, particularly in the pharmaceutical, fine chemicals, and flavor/fragrance industries. However, only a fraction of the enzymes available has been stepped up towards industrial-scale manufacturing due to low enzyme stability and challenging separation, recovery, and reusability. In this context, immobilization and co-immobilization in robust support materials have emerged as valuable strategies to overcome these inadequacies by facilitating repeated or continuous batch operations and downstream processes. To further reduce separations, it can be advantageous to use multiple enzymes at once in one pot. Enzyme co-immobilization enables biocatalytic synergism and reusability, boosting process efficiency and cost-effectiveness. Several studies on multi-enzyme immobilization and co-localization propose kinetic advantages of the enhanced turnover number for multiple enzymes. This review spotlights recent progress in developing versatile biocatalytic cascade systems by multi-enzyme co-immobilization on environmentally friendly biopolymers and nanostructured materials and their application scope in the chemical and biotechnological industries. After a succinct overview of carrier-based and carrier-free immobilization/co-immobilizations, co-immobilization of enzymes on a range of biopolymer and nanomaterials-based supports is thoroughly compiled with contemporary and state-of-the-art examples. This study provides a new horizon in developing effective and innovative multi-enzymatic systems with new possibilities to fully harness the adventure of biocatalytic systems.

Innovations in the synthesis of graphene nanostructures for bio and gas sensors

Sensors play a significant role in modern technologies and devices used in industries, hospitals, healthcare, nanotechnology, astronomy, and meteorology. Sensors based upon nanostructured materials have gained special attention due to their high sensitivity, precision accuracy, and feasibility. This review discusses the fabrication of graphene-based biosensors and gas sensors, which have highly efficient performance. Significant developments in the synthesis routes to fabricate graphene-based materials with improved structural and surface properties have boosted their utilization in sensing applications. The higher surface area, better conductivity, tunable structure, and atom-thick morphology of these hybrid materials have made them highly desirable for the fabrication of flexible and stable sensors. Many publications have reported various modification approaches to improve the selectivity of these materials. In the current work, a compact and informative review focusing on the most recent developments in graphene-based biosensors and gas sensors has been designed and delivered. The research community has provided a complete critical analysis of the most robust case studies from the latest fabrication routes to the most complex challenges. Some significant ideas and solutions have been proposed to overcome the limitations regarding the field of biosensors and hazardous gas sensors.

Nanomaterials and Their Impact on the Immune System

Nanomaterials have been the focus of intensive development and research in the medical and industrial sectors over the past several decades. Some studies have found that these compounds can have a detrimental impact on living organisms, including their cellular components. Despite the obvious advantages of using nanomaterials in a wide range of applications, there is sometimes skepticism caused by the lack of substantial proof that evaluates potential toxicities. The interactions of nanoparticles (NPs) with cells of the immune system and their biomolecule pathways are an area of interest for researchers. It is possible to modify NPs so that they are not recognized by the immune system or so that they suppress or stimulate the immune system in a targeted manner. In this review, we look at the literature on nanomaterials for immunostimulation and immunosuppression and their impact on how changing the physicochemical features of the particles could alter their interactions with immune cells for the better or for the worse (immunotoxicity). We also look into whether the NPs have a unique or unexpected (but desired) effect on the immune system, and whether the surface grafting of polymers or surface coatings makes stealth nanomaterials that the immune system cannot find and get rid of.

Influence of Laboratory Synthesized Graphene Oxide on the Morphology and Properties of Cement Mortar

The introduction of Graphene Oxide (GO), a nanomaterial, has shown considerable promise in improving the mechanical properties of cement composites. However, the reasons for this improvement are not yet fully understood and demand further research. This study aims to understand the effect of laboratory-produced GO, using Tour's method, on the mechanical properties and morphology of cement mortar containing GO. The GO was characterized using Fourier-transform infrared spectroscopy, X-ray Photoelectron Spectroscopy (XRD), X-ray powder diffraction, and Raman spectroscopy alongside Scanning electron microscopy (SEM). This study adopted a cement mortar with GO percentages of 0.02, 0.025, 0.03, 0.035, and 0.04 with respect to the weight of the cement. The presence of GO in cement mortar increased the density and decreased the consistency and setting times. At the optimum of 0.03% GO viscous suspension, the mechanical properties such as the 28-day compressive strength, splitting tensile strength, and flexural strength were enhanced by 41%, 83%, and 43%, respectively. In addition, Brunauer-Emmett-Teller analysis indicates an increase in surface area and volume of micropores of GO cement mortar, resulting in a decreased volume of mesopores. The improvement in properties was due to increased nucleation sites, calcium silicate hydrate (CSH) density, and a decreased volume of mesopores.

A Bioluminescent Protein-Graphene Oxide Donor-Quencher Pair in DNA Hybridization Assays

Despite fluorescent quenching with graphene oxide (GO) having shown great success in various applications - bioluminescent quenching has not yet been demonstrated using GO as a quencher. To explore the ability of GO to quench bioluminescence, we used Gaussia luciferase (Gluc) as a donor and GO as a quencher and demonstrated its application in sensing of two target analytes, HIV-1 DNA and IFN-γ. We demonstrated that the incubation of Gluc conjugated HIV-1 and IFN-γ oligonucleotide probes with GO provided for monitoring of probe-target interactions based on bioluminescence measurement in a solution phase sensing system. The limits of detection obtained for IFN-γ and HIV-1 DNA detection were 17 nM and 7.59 nM, respectively. Both sensing systems showed selectivity toward the target analyte. The detection of IFN-γ in saliva matrix was demonstrated. The use of GO as a quencher provides for high sensitivity while maintaining the selectivity of designed probes to their respective targets. The use of GO as a quencher provides for an easy assay design and low cost, environmentally friendly reporter.

Graphene oxide decreases the abundance of nitrogen cycling microbes and slows nitrogen transformation in soils

Graphene oxide (GO) has been widely used in many applications due to its excellent properties. Given the extensive production and use of this nanomaterial, its release into the environment is inevitable. However, little is known about the effects of GO on microbial nitrogen transformation and the related processes after GO enters the soil environment. The present study showed that GO significantly reduced soil microbial biomass and caused a decline in microbial diversity after the soils were subjected to various GO concentrations (10, 100, and 1000 mg kg^-1) for 4 months. Among them, the abundances of nitrogen transformation related bacteria such as Firmicutes, Nitrospirota, Proteobacteria, Planctomycetota, and Cyanobacteria were significantly decreased with GO incubation. Among the enzymes that are related to nitrogen transformation, nitrate reductase was the most sensitive even at low concentrations of GO, followed by ammonia monooxygenase and urease, which were reduced by 13-31%, 5-26%, and 9-19% respectively, than those of the control. We found that high concentrations of GO significantly increased the retention of soil urea by 32-59%, and the contents of ammonium and nitrate were 22-28% and 55-69% lower compared to those of the control, respectively. Moreover, the response of most of the indicators in the above process to multilayer GO was more significant than that to single layer GO. Overall, this study provides new insights into the comprehensive understanding of GO's impacts on the soil nitrogen cycle.

Comparison of Optical and Electrical Sensor Characteristics for Efficient Analysis of Attachment and Detachment of Aptamer

Nucleic acid aptamer-based research has focused on achieving the highest performance for bioassays. However, there are limitations in evaluating the affinity for the target analytes in these nucleic acid aptamer-based bioassays. In this study, we mainly propose graphene oxide (GO)-based electrical and optical analyses to efficiently evaluate the affinity between an aptamer and its target. We found that an aptamer-coupled GO-based chip with an electrical resistance induced by a field-effect transistor, with aptamers as low as 100 pM, can detect the target, thrombin, at yields as low as 250 pM within five minutes. In the optical approach, the fluorescent dye-linked aptamer, as low as 100 nM, was efficiently used with GO, enabling the sensitive detection of thrombin at yields as low as 5 nM. The cantilever type of mechanical analysis also demonstrated the intuitive aptamer-thrombin reaction in the signal using dBm units. Finally, a comparison of electrical and optical sensors' characteristics was introduced in the attachment and detachment of aptamer to propose an efficient analysis that can be utilized for various aptamer-based research fields.