Graphene oxide: a nonspecific enhancer of cellular growth

Rheological, electrochemical, and microstructural properties of graphene oxides as flowable electrodes for energy storage applications

Interest in novel energy storage and conversion methods has prompted a broad interest in potential applications of conductive, complex materials such as graphene oxide slurries. Investigating the complex rheological, material, and chemical properties of chemically exfoliated graphene oxide suspensions is a potential means to address that interest. The morphological size and clustering, rheology, and electronic conductivity are determined to characterize the properties of graphene oxide (GO) suspensions from variable centrifugation speeds. The evolution of viscosity is then analyzed under oscillatory shear, steady shear, and transient shear characteristics. The resulting microstructure is then analyzed via neutron scattering analysis and imaged with scanning electron microscopy. Small-Angle Neutron Scattering (SANS) of a 500g centrifuged GO suspension determined that particle structure is locally flat sheet-like at lengths below 100 nm, crumpled aggregates of GO sheets with surface roughness at length scales from 200 nm to 2 μm, and a dense mass fractal of overlapping GO sheets extending up to length scales of 20 μm. Increased centrifugation force of the 1000g GO suspension corresponded with lower zero-shear viscosity, yield stress, and less pronounced thixotropic behavior. Rheo-dielectric measurements were conducted on 1000g and 500g GO suspensions to determine the ohmic resistance, electronic conductivity, and specific capacitance. The more fluid-like microstructure of 1000g with smaller monodispered thinning GO sheets in suspension had lower ohmic resistance and higher electronic conductivity compared to the 500g GO suspension with more polydispersed larger aggregates. The 1000g GO suspension had the highest specific capacitance of 4.63 mF cm-2 at the highest shear rate of 700 s-1 due to the higher frequency of particle-particle collisions during shear within the network of smaller and more intrinsically conductive GO sheets to store charge. Therefore, the results of this study have implications for future studies in flowable carbon nanomaterials in flow battery and flow capacitor technologies.

Advanced Thermoactive Nanomaterials for Thermomedical Tissue Regeneration: Opportunities and Challenges

Nanomaterials usually possess remarkable properties, including excellent biocompatibility, unique physical and chemical characteristics, and bionic attributes, which make them highly promising for applications in tissue regeneration. Thermal therapy has emerged as a versatile approach for wound healing, nerve repair, bone regeneration, tumor therapy, and antibacterial tissue regeneration. By combining nanomaterials with thermal therapy, multifunctional nanomaterials with thermogenic effects and tissue regeneration capabilities can be engineered to achieve enhanced therapeutic outcomes. This study provides a comprehensive review of the effects of thermal stimulation on cellular and tissue regeneration. Furthermore, it highlights the applications of photothermal, magnetothermal, and electrothermal nanomaterials, and thermally responsive drug delivery systems in tissue engineering. In Addition, the bioactivities and biocompatibilities of several representative thermal nanomaterials are discussed. Finally, the challenges facing thermal nanomaterials are outlined, and future prospects in the field are presented with the aim of offering new opportunities and avenues for the utilization of thermal nanomaterials in tissue regeneration.

Vertical graphene nanoarray decorated with Ag nanoparticles exhibits enhanced antibacterial effects

Bacterial infection of biomedical implants is an important clinical challenge, driving the development of novel antimicrobial materials. The antibacterial effect of vertically aligned graphene as a nanoarray coating has been reported. In this study, vertically aligned graphene nanosheets decorated with silver nanoparticles were fabricated to enhance antibacterial effectiveness. Vertical graphene (VG) nanoflakes were synthesized by plasma-enhanced chemical vapor deposition (PECVD). Ag nanoparticles were attached to the surface of VG through using polydopamine and achieving a sustained release of Ag+. VG loaded with Ag nanoparticles (VGP/Ag) not only prevented bacterial adhesion for a long time, but also exhibited good biocompatibility. This work provides a new venue for designing antibacterial surfaces based on combination of graphene nanoarrays with other nanomaterials, and the results indicate that this approach could be very successful in preventing implant associated infections.

Biomimetic cell stimulation with a graphene oxide antigen-presenting platform for developing T cell-based therapies

Chimeric antigen receptor (CAR)-engineered T cells represent a front-line therapy for cancers. However, the current CAR T cell manufacturing protocols do not adequately reproduce immunological synapse formation. Here, in response to this limitation, we have developed a flexible graphene oxide antigen-presenting platform (GO-APP) that anchors antibodies onto graphene oxide. By decorating anti-CD3 (αCD3) and anti-CD28 (αCD28) on graphene oxide (GO-APP3/28), we achieved remarkable T cell proliferation. In vitro interactions between GO-APP3/28 and T cells closely mimic the in vivo immunological synapses between antigen-presenting cells and T cells. This immunological synapse mimicry shows a high capacity for stimulating T cell proliferation while preserving their multifunctionality and high potency. Meanwhile, it enhances CAR gene-engineering efficiency, yielding a more than fivefold increase in CAR T cell production compared with the standard protocol. Notably, GO-APP3/28 stimulated appropriate autocrine interleukin-2 (IL-2) in T cells and overcame the in vitro reliance on external IL-2 supplementation, offering an opportunity to culture T cell-based products independent of IL-2 supplementation.

Waste Nitrogen Upcycling to Amino Acids during Anaerobic Fermentation on Biochar: An Active Strategy for Regulating Metabolic Reducing Power

This study proposes a novel strategy that utilizes biochar (BC) during anaerobic fermentation (AF) to generate amino acids (AAs) toward nitrogen upcycling. The BC, pyrolyzed at 800 °C (BC800) to enhance graphite structures and electron-accepting sites, effectively addresses issues related to biosynthetic reducing power nicotinamide adenine dinucleotide phosphate insufficiency by altering cellular conditions and alleviates feedback inhibition through the immobilization of end products. This process establishes unique microbial signaling and energy networks, with Escherichia coli becoming dominant in the biofilm. The conversion rate of ammonia-N to AAs-N within the biofilm reached 67.4% in BC800-AF, which was significantly higher compared to the levels in other AF reactors with BC pyrolyzed at 600 and 400 °C (45.9 and 22.5%, respectively), as well as a control AF reactor (<5%). Furthermore, in BC800-AF, the aromatic AAs (Aro-AAs) were as high as 70.8% of the AAs within the biofilm. The activities of key enzymes for Aro-AAs biosynthesis uniquely positively correlated with the electron-accepting capacity on BC800 (R2 ≥ 0.95). These findings hold promise for transforming existing AF reactors into factories that produce BC-based AAs, providing a more sustainable fertilizing agent than chemical fertilizers.

The effects of graphene on low-temperature anammox process: The insights from short-term tests and long-term operation

Effluent quality deterioration caused by seasonal low temperature is a great challenge to the application of anammox technology. Here, the effects of different graphene materials on anammox process were investigated under both optimal temperature and low-temperature. The batch tests showed that at 30 °C, 300 mg/L of reduced graphene oxide‑sodium alginate gel (RGOSA) had the most significant promoting effect, reaching nitrogen removal efficiency (NRE) and nitrogen removal rate (NRR) of 95 % and 8.88 mgN/L/d, respectively. The changes of EPS secretion patterns and increasing of key enzymes activity might contribute to the enhanced anammox activity. During the long-term operation of anammox reactor, the NRE and NRR of the reactor decreased when the temperature dropped to 15 °C, showing an NRE of 50 %-57 % with the addition of 200 mg/L of reduced graphene oxide (RGO) and 40 %-45 % with the addition of 20 mg/L of RGO. Furthermore, specific anammox activity (SAA) of the RGO200 reactor at 15 °C increased by 57.1 % compared to the UASB reactor without graphene addition. Additionally, 16S rRNA and metagenomic analysis results revealed anammox bacteria Ca. Kuenenia was the dominant bacteria. Moreover, the RGO can significantly increase the relative abundance of N-converting functional genes. This study demonstrates the graphene materials can help anammox process adapting to low temperatures, providing a possible solution for the application of anammox technology.

Synergistic effects of thermally reduced graphene oxide/zinc oxide composite material on microbial infection for wound healing applications

Infections originating from pathogenic microorganisms can significantly impede the natural wound-healing process. To address this obstacle, innovative bio-active nanomaterials have been developed to enhance antibacterial capabilities. This study focuses on the preparation of nanocomposites from thermally reduced graphene oxide and zinc oxide (TRGO/ZnO). The hydrothermal method was employed to synthesize these nanocomposites, and their physicochemical properties were comprehensively characterized using X-ray diffraction analysis (XRD), High-resolution transmission electron microscopy (HR-TEM), Fourier-transform infrared (FT-IR), Raman spectroscopy, UV-vis, and field-emission scanning electron microscopy (FE-SEM) techniques. Subsequently, the potential of TRGO/ZnO nanocomposites as bio-active materials against wound infection-causing bacteria, including Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, was evaluated. Furthermore, the investigated samples show disrupted bacterial biofilm formation. A reactive oxygen species (ROS) assay was conducted to investigate the mechanism of nanocomposite inhibition against bacteria and for further in-vivo determination of antimicrobial activity. The MTT assay was performed to ensure the safety and biocompatibility of nanocomposite. The results suggest that TRGO/ZnO nanocomposites have the potential to serve as effective bio-active nanomaterials for combating pathogenic microorganisms present in wounds.

Effects of graphene oxide and graphene quantum dots on enhancing CPP-ACP anti-caries ability of enamel lesion in a biofilm-challenged environment

OBJECTIVE

To investigate the anticaries effects of graphene oxide (GO) and graphene quantum dots (GQDs) combined with casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on enamel in a biofilm-challenged environment.

MATERIAL AND METHODS

GO and GQDs were synthesised using citric acid. The antibiofilm and biofilm inhibition effects for Streptococcus mutans were evaluated by scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), and colony-forming units (CFU). Remineralisation ability was determined by assessing mineral loss, calcium-to-phosphorus ratio, and surface morphology. To create a biofilm-challenged environment, enamel blocks were immersed in S. mutans to create the lesion and then subjected to artificial saliva/biofilm cycling for 7 days. Anticaries effects of GO, GQDs, GQDs@CPP-ACP, GO@CPP-ACP, and CPP-ACP were determined by broth pH and mineral changes after 7-day pH cycling. Biocompatibility was tested using a Cell Counting Kit-8 (CCK8) assay for human gingival fibroblasts (HGF-1).

RESULTS

GQDs and GO presented significant antibiofilm and biofilm inhibition effects compared to the CPP-ACP and control groups (P < 0.05). The enamel covered by GQDs and GO showed better crystal structure formation and less mineral loss (P < 0.05) than that covered by CPP-ACP alone. After 7 days in the biofilm-challenged environment, the GO@CPP-ACP group showed less lesion depth than the CPP-ACP and control groups (P < 0.05). GO and GQDs showed good biocompatibility compared to the control group by CCK8 (P > 0.05) within 3 days.

CONCLUSION

GO and GQDs could improve the anti-caries effects of CPP-ACP, and CPP-ACP agents with GO or GQDs could be a potential option for enamel lesion management.

CLINICAL SIGNIFICANCE

GO and GQDs have demonstrated the potential to significantly enhance the anticaries effects of CPP-ACP. Incorporating these nanomaterials into CPP-ACP formulations could provide innovative and effective options for the management of enamel lesions, offering improved preventive and therapeutic strategies in dental care.

Interactions of graphene oxide with the microbial community of biologically active filters from a water treatment plant

With widespread occurrence and increasing concern of emerging contaminants (CECs) in source water, biologically active filters (BAF) have been gaining acceptance in water treatment. Both BAFs and graphene oxide (GO) have been shown to be effective in treating CECs. However, studies to date have not addressed interactions between GO and microbial communities in water treatment processes such as BAFs. Therefore, in the present study, we investigated the effect of GO on the properties and microbial growth rate in a BAF system. Synthesized GO was characterized with a number of tools, including scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Raman spectrometry. GO exhibited the characteristic surface functional groups (i.e., C-OH, C=O, C-O-C, and COOH), crystalline structure, and sheet-like morphology. To address the potential toxicity of GO on the microbial community, reactive oxygen species (ROS) generation was measured using nitro blue tetrazolium (NBT) assay. Results revealed that during the exponential growth phase, ROS generation was not observed in the presence of GO compared to the control batch. In fact, the adenosine triphosphate (ATP) concentrations increased in the presence of GO (25 μg/L - 1000 μg/L) compared to the control without GO. The growth rate in systems with GO exceeded the control by 20 % to 46 %. SEM images showed that GO sheets can form an effective scaffold to promote bacterial adhesion, proliferation, and biofilm formation, demonstrating its biocompatibility. Next-generation sequencing (Illumina MiSeq) was used to characterize the BAF microbial community, and high-throughput sequencing analysis confirmed the greater richness and more diverse microbial communities compared to systems without GO. This study is the first to report the effect of GO on the microbial community of BAF from a water treatment plant, which provides new insights into the potential of utilizing a bio-optimized BAF for advanced and sustainable water treatment or reuse strategies.

Chitosan/cellulose nanocrystals/graphene oxide scaffolds as a potential pH-responsive wound dressing: Tuning physico-chemical, pro-regenerative and antimicrobial properties

Chronic wounds (CWs) treatment still represents a demanding medical challenge. Several intrinsic physiological signals (i.e., pH) help to stimulate and support wound healing. CWs, in fact, are characterized by a predominantly alkaline pH of the exudate, which acidifies as the wound heals. Therefore, pH-responsive wound dressings hold great potential owing to their capability of tuning their functions according to the wound conditions. Herein, porous chitosan (CS)-based scaffolds loaded with cellulose nanocrystals (CNCs) and graphene oxide (GO) were successfully fabricated using a freeze-drying method. CNCs were extracted from bagasse pulps fibers through acid hydrolysis. GO was synthesised by Hummer's method. The scaffolds were then ionically cross-linked using the amino acid L-Arginine (Arg), as a bioactive agent, and tested as potential pH-responsive wound dressing. Notably, the effect of CNCs and GO singly and simultaneously loaded within the CS-Arg scaffolds was investigated. The modulation of CNCs and GO content within CS-Arg scaffolds facilitated the development of scaffolds with an optimal pH-dependent swelling ratio capability and extended degradation time. Furthermore, CS/CNC/GO-Arg scaffolds exhibited tuned biological features, in terms of antimicrobial activity, cellular proliferation/migration ability, and the expression of extracellular matrix specific markers (i.e., elastin and collagen I) related to wound healing in human dermal fibroblasts.

Mitigative Effect of Graphene Oxide Nanoparticles in Maintaining Gut–Liver Homeostasis against Alcohol Injury

Alcoholic liver disease (ALD) develops when the immunotolerant environment of the liver is compromised due to excessive alcohol consumption. ALD progression involves variations in the expressions of multiple genes, resulting in liver inflammation and the development of a leaky gut. It is still unclear which molecular mechanism is involved in ALD progression, and due to that, there are currently no FDA-approved drugs available for its treatment. In this study, the protective effects of graphene oxide (GO) nanoparticles were investigated against ethanol-induced damage in the gut–liver axis in in vitro. GO was synthesized using a modified Hummer’s method, and characterization was performed. Given the general concerns regarding nanoparticle toxicity, assessments of cell viability, lipid accumulation, DNA damage, cell death, and the generation of reactive oxygen species (ROS) were conducted using various techniques. Furthermore, the gene expressions of pro- and anti-inflammatory cytokines were determined using RT-qPCR. The findings reveal that GO promoted cell viability even against ethanol treatment. Additionally, lipid accumulation significantly decreased when cells were treated with GO alongside ethanol compared to ethanol treatment alone, with similar trends observed for other assays. A gene expression analysis indicated that GO treatment reduced the expression of proinflammatory cytokines while enhancing the expression of antioxidant genes. Moreover, GO treatment led to improvements in gut integrity and a reduction in proinflammatory cytokines in colon cells damaged by ethanol. These findings suggest that GO holds promise as a drug carrier, exhibiting no observed toxic effects. By shedding light on the protective effects of GO against ethanol-induced damage, this study contributes to the burgeoning field of nanoparticle-mediated therapy for ALD.

An assessment of nanotechnology-based interventions for cleaning up toxic heavy metal/metalloid-contaminated agroecosystems: Potentials and issues

Heavy metals (HMs) are among the most dangerous environmental variables for a variety of life forms, including crops. Accumulation of HMs in consumables and their subsequent transmission to the food web are serious concerns for scientific communities and policy makers. The function of essential plant cellular macromolecules is substantially hampered by HMs, which eventually have a detrimental effect on agricultural yield. Among these HMs, three were considered, i.e., arsenic, cadmium, and chromium, in this review, from agro-ecosystem perspective. Compared with conventional plant growth regulators, the use of nanoparticles (NPs) is a relatively recent, successful, and promising method among the many methods employed to address or alleviate the toxicity of HMs. The ability of NPs to reduce HM mobility in soil, reduce HM availability, enhance the ability of the apoplastic barrier to prevent HM translocation inside the plant, strengthen the plant's antioxidant system by significantly enhancing the activities of many enzymatic and nonenzymatic antioxidants, and increase the generation of specialized metabolites together support the effectiveness of NPs as stress relievers. In this review article, to assess the efficacy of various NP types in ameliorating HM toxicity in plants, we adopted a 'fusion approach', in which a machine learning-based analysis was used to systematically highlight current research trends based on which an extensive literature survey is planned. A holistic assessment of HMs and NMs was subsequently carried out to highlight the future course of action(s).

Recent advances in synergistic use of GQD-based hydrogels for bioimaging and drug delivery in cancer treatment

Graphene quantum dot (GQD) integration into hydrogel matrices has become a viable approach for improving drug delivery and bioimaging in cancer treatment in recent years. Due to their distinct physicochemical characteristics, graphene quantum dots (GQDs) have attracted interest as adaptable nanomaterials for use in biomedicine. When incorporated into hydrogel frameworks, these nanomaterials exhibit enhanced stability, biocompatibility, and responsiveness to external stimuli. The synergistic pairing of hydrogels with GQDs has created new opportunities to tackle the problems related to drug delivery and bioimaging in cancer treatment. Bioimaging plays a pivotal role in the early detection and monitoring of cancer. GQD-based hydrogels, with their excellent photoluminescence properties, offer a superior platform for high-resolution imaging. The tunable fluorescence characteristics of GQDs enable real-time visualization of biological processes, facilitating the precise diagnosis and monitoring of cancer progression. Moreover, the drug delivery landscape has been significantly transformed by GQD-based hydrogels. Because hydrogels are porous, therapeutic compounds may be placed into them and released in a controlled environment. The large surface area and distinct interactions of graphene quantum dots (GQDs) with medicinal molecules boost loading capacity and release dynamics, ultimately improving therapeutic efficacy. Moreover, GQD-based hydrogels' stimulus-responsiveness allows for on-demand medication release, which minimizes adverse effects and improves therapeutic outcomes. The ability of GQD-based hydrogels to specifically target certain cancer cells makes them notable. Functionalizing GQDs with targeting ligands minimizes off-target effects and delivers therapeutic payloads to cancer cells selectively. Combined with imaging capabilities, this tailored drug delivery creates a theranostic platform for customized cancer treatment. In this study, the most recent advancements in the synergistic use of GQD-based hydrogels are reviewed, with particular attention to the potential revolution these materials might bring to the area of cancer theranostics.

Comparative toxicological analysis of two pristine carbon nanomaterials (graphene oxide and aminated graphene oxide) and their corresponding degraded forms using human in vitro models

Despite the wide application of graphene-based materials, the information of the toxicity associated to some specific derivatives such as aminated graphene oxide is scarce. Likewise, most of these studies analyse the pristine materials, while the available data regarding the harmful effects of degraded forms is very limited. In this work, the toxicity of graphene oxide (GO), aminated graphene oxide (GO-NH2), and their respective degraded forms (dGO and dGO-NH2) obtained after being submitted to high-intensity sonication was evaluated applying in vitro assays in different models of human exposure. Viability and ROS assays were performed on A549 and HT29 cells, while their skin irritation potential was tested on a reconstructed human epidermis model. The obtained results showed that GO-NH2 and dGO-NH2 substantially decrease cell viability in the lung and gastrointestinal models, being this reduction slightly higher in the cells exposed to the degraded forms. In contrast, this parameter was not affected by GO and dGO which, conversely, showed the ability to induce higher levels of ROS than the pristine and degraded aminated forms. Furthermore, none of the materials is skin irritant. Altogether, these results provide new insights about the potential harmful effects of the selected graphene-based nanomaterials in comparison with their degraded counterparts.

Iron decoration in binary graphene oxide and copper iron sulfide nanocomposites boosting catalytic antibacterial activity in acidic microenvironment against antimicrobial resistance

The strong antimicrobial resistance (AMR) of multidrug-resistant (MDR) bacteria and biofilm, especially the biofilm with extracellular polymeric substance (EPS) protection and persister cells, not only renders antibiotics ineffective but also causes chronic infections and makes the infectious tissue difficult to repair. Considering the acidic properties of bacterial infection microenvironment and biofilm, herein, a binary graphene oxide and copper iron sulfide nanocomposite (GO/CuFeSx NC) is synthesized by a surfactant free strategy and utilized as an alternative smart nanozyme to fight against the MDR bacteria and biofilm. For the GO/CuFeSx NC, the iron decoration facilitates the well distribution of bimetallic CuFeSx NPs on the GO surfaces compared to monometallic CuS NPs, providing synergistically enhanced peroxidase (POD)-like activity in acidic medium (pH 4 ∼ 5) and intrinsic strong near infrared (NIR) light responsive photothermal activity, while the ultrathin and sharp structure of 2D GO nanosheet allows the GO/CuFeSx NC to strongly interact with the bacteria and biofilm, facilitating the catalytic and photothermal attacks on the bacterial surfaces. In addition, the GO in GO/CuFeSx NC exhibits a "Pseudo-Photo-Fenton" effect to promote the ROS generation. Therefore, the GO/CuFeSx NC can effectively kill bacteria and biofilm both in vitro and in vivo, finally eliminating the infections and accelerating the tissue repair when treating the biofilm-infected wound. This work paves a new way to the design of novel nanozyme for smart antibacterial therapy against antimicrobial resistance.

Multidrug-Resistant Escherichia coli Remains Susceptible to Metal Ions and Graphene-Based Compounds

Escherichia coli is listed as a priority 1 pathogen on the World Health Organization (WHO) priority pathogen list. For this list of pathogens, new antibiotics are urgently needed to control the emergence and spread of multidrug-resistant strains. This study assessed eighteen metal ions, graphene, and graphene oxide for their antimicrobial efficacy against E. coli in both planktonic and biofilm growth states and the potential synergy between metal ions and graphene-based compounds. Molybdenum and tin ions exhibited the greatest antimicrobial activity against the planktonic states of the isolates with minimal inhibitory concentrations (MIC) ranging between 13 mg/L and 15.6 mg/L. Graphene oxide had no antimicrobial effect against any of the isolates, while graphene showed a moderate effect against E. coli (MIC, 62.5 mg/L). Combinations of metal ions and graphene-based compounds including tin-graphene, tin-graphene oxide, gold-graphene, platinum-graphene, and platinum-graphene oxide exhibited a synergistic antimicrobial effect (FIC ≤ 0.5), inhibiting the planktonic and biofilm formation of the isolates regardless of their antibiotic-resistant profiles. The bactericidal effect of the metal ions and the synergistic effects when combined with graphene/graphene oxide against medically relevant pathogens demonstrated that the antimicrobial efficacy was increased. Hence, such agents may potentially be used in the production of novel antimicrobial/antiseptic agents.

Effects of Graphene-Based Nanomaterials on Microorganisms and Soil Microbial Communities

The past decades have witnessed intensive research on the biological effects of graphene-based nanomaterials (GBNs) and the application of GBNs in different fields. The published literature shows that GBNs exhibit inhibitory effects on almost all microorganisms under pure culture conditions, and that this inhibitory effect is influenced by the microbial species, the GBN's physicochemical properties, the GBN's concentration, treatment time, and experimental surroundings. In addition, microorganisms exist in the soil in the form of microbial communities. Considering the complex interactions between different soil components, different microbial communities, and GBNs in the soil environment, the effects of GBNs on soil microbial communities are undoubtedly intertwined. Since bacteria and fungi are major players in terrestrial biogeochemistry, this review focuses on the antibacterial and antifungal performance of GBNs, their antimicrobial mechanisms and influencing factors, as well as the impact of this effect on soil microbial communities. This review will provide a better understanding of the effects of GBNs on microorganisms at both the individual and population scales, thus providing an ecologically safe reference for the release of GBNs to different soil environments.

2D Nanomaterials and Their Drug Conjugates for Phototherapy and Magnetic Hyperthermia Therapy of Cancer and Infections

Photothermal therapy (PTT) and magnetic hyperthermia therapy (MHT) using 2D nanomaterials (2DnMat) have recently emerged as promising alternative treatments for cancer and bacterial infections, both important global health challenges. The present review intends to provide not only a comprehensive overview, but also an integrative approach of the state-of-the-art knowledge on 2DnMat for PTT and MHT of cancer and infections. High surface area, high extinction coefficient in near-infra-red (NIR) region, responsiveness to external stimuli like magnetic fields, and the endless possibilities of surface functionalization, make 2DnMat ideal platforms for PTT and MHT. Most of these materials are biocompatible with mammalian cells, presenting some cytotoxicity against bacteria. However, each material must be comprehensively characterized physiochemically and biologically, since small variations can have significant biological impact. Highly efficient and selective in vitro and in vivo PTTs for the treatment of cancer and infections are reported, using a wide range of 2DnMat concentrations and incubation times. MHT is described to be more effective against bacterial infections than against cancer therapy. Despite the promising results attained, some challenges remain, such as improving 2DnMat conjugation with drugs, understanding their in vivo biodegradation, and refining the evaluation criteria to measure PTT or MHT effects.

Ciprofloxacin-, Cefazolin-, and Methicilin-Soaked Graphene Paper as an Antibacterial Medium Suppressing Cell Growth

This paper presents the results of research on the impact of graphene paper on selected bacterial strains. Graphene oxide, from which graphene paper is made, has mainly bacteriostatic properties. Therefore, the main goal of this research was to determine the possibility of using graphene paper as a carrier of a medicinal substance. Studies of the degree of bacterial inhibition were performed on Staphylococcus aureus and Pseudomonas aeruginosa strains. Graphene paper was analyzed not only in the state of delivery but also after the incorporation of the antibiotics ciprofloxacin, cefazolin, and methicillin into its structures. In addition, Fourier-Transform Infrared Spectroscopy, contact angle, and microscopic analysis of bacteria on the surface of the examined graphene paper samples were also performed. Studies have shown that graphene paper with built-in ciprofloxacin had a bactericidal effect on the strains of Staphylococcus aureus and Pseudomonas aeruginosa. In contrast, methicillin, as well as cefazolin, deposited on graphene paper acted mainly locally. Studies have shown that graphene paper can be used as a carrier of selected medicinal substances.

Anammox with alternative electron acceptors: perspectives for nitrogen removal from wastewaters

In the context of the anaerobic ammonium oxidation process (anammox), great scientific advances have been made over the past two decades, making anammox a consolidated technology widely used worldwide for nitrogen removal from wastewaters. This review provides a detailed and comprehensive description of the anammox process, the microorganisms involved and their metabolism. In addition, recent research on the application of the anammox process with alternative electron acceptors is described, highlighting the biochemical reactions involved, its advantages and potential applications for specific wastewaters. An updated description is also given of studies reporting the ability of microorganisms to couple the anammox process to extracellular electron transfer to insoluble electron acceptors; particularly iron, carbon-based materials and electrodes in bioelectrochemical systems (BES). The latter, also referred to as anodic anammox, is a promising strategy to combine the ammonium removal from wastewater with bioelectricity production, which is discussed here in terms of its efficiency, economic feasibility, and energetic aspects. Therefore, the information provided in this review is relevant for future applications.

Harnessing two-dimensional nanomaterials for diagnosis and therapy in neurodegenerative diseases: Advances, challenges and prospects

Neurodegenerative diseases (NDDs) are specific brain disorders characterized by the progressive deterioration of different motor activities as well as several cognitive functions. Current conventional therapeutic options for NDDs are limited in addressing underlying causes, delivering drugs to specific neuronal targets, and promoting tissue repair following brain injury. Due to the paucity of plausible theranostic options for NDDs, nanobiotechnology has emerged as a promising field, offering an interdisciplinary approach to create nanomaterials with high diagnostic and therapeutic efficacy for these diseases. Recently, two-dimensional nanomaterials (2D-NMs) have gained significant attention in biomedical and pharmaceutical applications due to their precise drug-loading capabilities, controlled release mechanisms, enhanced stability, improved biodegradability, and reduced cell toxicity. Although various studies have explored the diagnostic and therapeutic potential of different nanomaterials in NDDs, there is a lack of comprehensive review addressing the theranostic applications of 2D-NMs in these neuronal disorders. Therefore, this concise review aims to provide a state-of-the-art understanding of the need for these ultrathin 2D-NMs and their potential applications in biosensing and bioimaging, targeted drug delivery, tissue engineering, and regenerative medicine for NDDs.

Chemical Method for Recovery and Regeneration of Graphene Oxide

Graphene oxide (GO) has been developed as a very effective medium for filtration and removal of microbial contaminants in fuel. GO is capable of filtering out microorganisms without needing micrometer and submicrometer pores for filtration. Our previous studies showed that microorganisms are attracted by GO and bind irreversibly to GO without promoting bacterial growth. Therefore, GO was tested as a filter medium to remove microorganisms in fuel. The characterization results showed that GO removed microbes in diesel fuel with >99% efficiency. However, the synthesis of GO using Hummers' method is labor intensive and a time-consuming. We present in this paper an economical, less labor intensive and a simple chemical approach to recover GO after it has been used as a filtration medium for the removal of microorganisms in fuels. In the GO recovery process, microbial and fuel contaminated GO is washed with hexane to remove any fuel from the GO sample. The hexane-washed GO is further washed with acetone and mixed with ethanol to kill and remove any microorganisms. After washing with ethanol, the GO sample is sonicated in water to remove impurities and re-establish the oxygen functionalities. The final recovered-GO (rec-GO) is obtained after removing water by rotary evaporation. The chemical characterization of rec-GO showed that rec-GO is similar in both chemical and physical properties compared to freshly synthesized-GO (as-syn-GO). Rec-GO was shown to perform similarly to as-syn-GO in filtration of biocontaminated fuel. We estimate that our rec-GO is at least 90% cheaper than high quality commercially available GO.

Graphene-Based Nanomaterials and Their Interactions with Lipid Membranes

Graphene-based nanomaterials (GNMs) have captured increasing attention in the recent advancement of materials science and nanotechnology owing to their excellent physicochemical properties. Despite having unquestionable advances, the application of GNMs in biological and medical sciences is still limited due to the lack of knowledge and precise control over their interaction with the biological milieu. The cellular membrane is the first barrier with which GNMs interact before entering a cell. Therefore, understanding how they interact with cell membranes is important from the perspective of safe use in biological and biomedical fields. In this review, we systematically summarize the recent efforts in predicting the interactions between GNMs and model cellular membranes. This review provides insights into how GNMs interact with lipid membranes and self-assemble in and around them. Both the computational simulations and experimental observations are summarized. The interactions are classified depending on the physicochemical properties (structure, chemistry, and orientation) of GNMs and various model membranes. The thermodynamic parameters, structural details, and supramolecular forces are listed to understand the interactions which would help circumvent potential risks and provide guidance for safe use in the future. At the end of this review, future prospective and emerging challenges in this research field are discussed.

Novel insights into carbon nanomaterials enhancing anammox for nitrogen removal: Effects and mechanisms

Carbon nanomaterials (CNMs) possess the properties including large specific surface area, high porosity, and stable chemical structures, presenting significant application advantages in wastewater treatment. Indeed, CNMs are considered to be added to anammox systems to strengthen anammox function, especially to resolve the challenge of anammox technology, i.e., the slow growth rate of anammox bacteria, as well as its high environmental sensitivity. This paper systematically reviews the promotion effects and mechanisms of CNMs on the nitrogen removal performance of anammox system. Among the zero-, one-, and two-dimensional CNMs, two-dimensional CNMs have best promoting effect on the nitrogen removal performance of anammox system due to its excellent conductivity and abundant functional groups. Then, the promotion effects of CNMs on anammox process are summarized from the perspective of anammox activity and bacteria abundance. Furthermore, CNMs not only enhance the anammox process, but also stimulate the coupling of denitrification pathways with anammox, as well as the improvement of system operational stability (alleviating the inhibitions of low temperature and pH fluctuation), thus contributing to the promoted nitrogen removal performance. Essentially, CNMs are capable of facilitating microbial immobilization and electron transfer, which favor to improve the efficiency and stability of anammox process. Finally, this review highlights the gap in knowledge and future work, aiming to provide a deeper understanding of how CNMs can strengthen the anammox system and provide a novel perspective for the engineering of the anammox process.

Ameliorating Effects of Graphene Oxide on Cadmium Accumulation and Eco-Physiological Characteristics in a Greening Hyperaccumulator (Lonicera japonica Thunb.)

Graphene oxide (GO), as a novel carbon-based nanomaterial (CBN), has been widely applied to every respect of social life due to its unique composite properties. The widespread use of GO inevitably promotes its interaction with heavy metal cadmium (Cd), and influences its functional behavior. However, little information is available on the effects of GO on greening hyperaccumulators under co-occurring Cd. In this study, we chose a typical greening hyperaccumulator (Lonicera japonica Thunb.) to show the effect of GO on Cd accumulation, growth, net photosynthesis rate (Pn), carbon sequestration and oxygen release functions of the plant under Cd stress. The different GO-Cd treatments were set up by (0, 10, 50 and 100 mg L-1) GO and (0, 5 and 25 mg L-1) Cd in solution culture. The maximum rate of Cd accumulation in the roots and shoots of the plant were increased by 10 mg L-1 GO (exposed to 5 mg L-1 Cd), indicating that low-concentration GO (10 mg L-1) combined with low-concentration Cd (5 mg L-1) might stimulate the absorption of Cd by L. japonica. Under GO treatments without Cd, the dry weight of root and shoot biomass, Pn value, carbon sequestration per unit leaf area and oxygen release per unit leaf area all increased in various degrees, especially under 10 mg L-1 GO, were 20.67%, 12.04%, 35% and 28.73% higher than the control. Under GO-Cd treatments, it is observed that the cooperation of low-concentration GO (10 mg L-1) and low-concentration Cd (5 mg L-1) could significantly stimulate Cd accumulation, growth, photosynthesis, carbon sequestration and oxygen release functions of the plant. These results indicated that suitable concentrations of GO could significantly alleviate the effects of Cd on L. japonica, which is helpful for expanding the phytoremediation application of greening hyperaccumulators faced with coexistence with environment of nanomaterials and heavy metals.

Effect of anode material and dispersal limitation on the performance and biofilm community in microbial electrolysis cells

In a microbial electrolysis cell (MEC), the oxidization of organic compounds is facilitated by an electrogenic biofilm on the anode surface. The biofilm community composition determines the function of the system. Both deterministic and stochastic factors affect the community, but the relative importance of different factors is poorly understood. Anode material is a deterministic factor as materials with different properties may select for different microorganisms. Ecological drift is a stochastic factor, which is amplified by dispersal limitation between communities. Here, we compared the effects of three anode materials (graphene, carbon cloth, and nickel) with the effect of dispersal limitation on the function and biofilm community assembly. Twelve MECs were operated for 56 days in four hydraulically connected loops and shotgun metagenomic sequencing was used to analyse the microbial community composition on the anode surfaces at the end of the experiment. The anode material was the most important factor affecting the performance of the MECs, explaining 54-80 % of the variance observed in peak current density, total electric charge generation, and start-up lag time, while dispersal limitation explained 10-16 % of the variance. Carbon cloth anodes had the highest current generation and shortest lag time. However, dispersal limitation was the most important factor affecting microbial community structure, explaining 61-98 % of the variance in community diversity, evenness, and the relative abundance of the most abundant taxa, while anode material explained 0-20 % of the variance. The biofilms contained nine Desulfobacterota metagenome-assembled genomes (MAGs), which made up 64-89 % of the communities and were likely responsible for electricity generation in the MECs. Different MAGs dominated in different MECs. Particularly two different genotypes related to Geobacter benzoatilyticus competed for dominance on the anodes and reached relative abundances up to 83 %. The winning genotype was the same in all MECs that were hydraulically connected irrespective of anode material used.

Graphene oxide as novel vaccine adjuvant

To improve antigen immunogenicity and promote long-lasting immunity, vaccine formulations have been appropriately supplemented with adjuvants. Graphene has been found to enhance the presentation of antigens to CD8+ T cells, as well as stimulating innate immune responses and inflammatory factors. Its properties, such as large surface area, water stability, and high aspect ratio, make it a suitable candidate for delivering biological substances. Graphene-based nanomaterials have recently attracted significant attention as a new type of vaccine adjuvants due to their potential role in the activation of immune responses. Due to the limited functionality of some approved human adjuvants for use, the development of new all-purpose adjuvants is urgently required. Research on the immunological and biomedical use of graphene oxide (GO) indicates that these nanocarriers possess excellent physicochemical properties, acceptable biocompatibility, and a high capacity for drug loading. Graphene-based nanocarriers also could improve the function of some immune cells such as dendritic cells and macrophages through specific signaling pathways. However, GO injection can lead to significant oxidative stress and inflammation. Various surface functionalization protocols have been employed to reduce possible adverse effects of GO, such as aggregation of GO in biological liquids and induce cell death. Furthermore, these modifications enhance the properties of functionalized-GO's qualities, making it an excellent carrier and adjuvant. Shedding light on different physicochemical and structural properties of GO and its derivatives has led to their application in various therapeutic and drug delivery fields. In this review, we have endeavored to elaborate on different aspects of GO.

The Effect of Chitosan/Alginate/Graphene Oxide Nanocomposites on Proliferation of Mouse Spermatogonial Stem Cells

Male survivors of childhood cancer have been known to be afflicted with azoospermia. To combat this, the isolation and purification of spermatogonial stem cells (SSCs) are crucial. Implementing scaffolds that emulate the extracellular matrix environment is vital for promoting the regeneration and proliferation of SSCs. This research aimed to evaluate the efficiency of nanocomposite scaffolds based on alginate, chitosan, and graphene oxide (GO) in facilitating SSCs proliferation. To analyze the cytotoxicity of the scaffolds, an MTT assay was conducted at 1, 3, and 7 days, and the sample containing 30 µg/mL of GO (ALGCS/GO30) exhibited the most favorable results, indicating its optimal performance. The identity of the cells was confirmed using flow cytometry with C-Kit and GFRα1 markers. The scaffolds were subjected to various analyses to characterize their properties. FTIR was employed to assess the chemical structure, XRD to examine crystallinity, and SEM to visualize the morphology of the scaffolds. To evaluate the proliferation of SSCs, qRT-PCR was used. The study's results demonstrated that the ALGCS/GO30 nanocomposite scaffold exhibited biocompatibility and facilitated the attachment and proliferation of SSCs. Notably, the scaffold displayed a significant increase in proliferation markers compared to the control group, indicating its ability to support SSC growth. The expression level of the PLZF protein was assessed using the Immunocytochemistry method. The observations confirmed the qRT-PCR results, which indicated that the nanocomposite scaffolds had higher levels of PLZF protein expression than scaffolds without GO. The biocompatible ALGCS/GO30 is a promising alternative for promoting SSC proliferation in in vitro applications.

Reduced graphene oxide coated alginate scaffolds: potential for cardiac patch application

BACKGROUND

Cardiovascular diseases, particularly myocardial infarction (MI), are the leading cause of death worldwide and a major contributor to disability. Cardiac tissue engineering is a promising approach for preventing functional damage or improving cardiac function after MI. We aimed to introduce a novel electroactive cardiac patch based on reduced graphene oxide-coated alginate scaffolds due to the promising functional behavior of electroactive biomaterials to regulate cell proliferation, biocompatibility, and signal transition.

METHODS

The fabrication of novel electroactive cardiac patches based on alginate (ALG) coated with different concentrations of reduced graphene oxide (rGO) using sodium hydrosulfite is described here. The prepared scaffolds were thoroughly tested for their physicochemical properties and cytocompatibility. ALG-rGO scaffolds were also tested for their antimicrobial and antioxidant properties. Subcutaneous implantation in mice was used to evaluate the scaffolds' ability to induce angiogenesis.

RESULTS

The Young modulus of the scaffolds was increased by increasing the rGO concentration from 92 ± 4.51 kPa for ALG to 431 ± 4.89 kPa for ALG-rGO-4 (ALG coated with 0.3% w/v rGO). The scaffolds' tensile strength trended similarly. The electrical conductivity of coated scaffolds was calculated in the semi-conductive range (~ 10-4 S/m). Furthermore, when compared to ALG scaffolds, human umbilical vein endothelial cells (HUVECs) cultured on ALG-rGO scaffolds demonstrated improved cell viability and adhesion. Upregulation of VEGFR2 expression at both the mRNA and protein levels confirmed that rGO coating significantly boosted the angiogenic capability of ALG against HUVECs. OD620 assay and FE-SEM observation demonstrated the antibacterial properties of electroactive scaffolds against Escherichia coli, Staphylococcus aureus, and Streptococcus pyogenes. We also showed that the prepared samples possessed antioxidant activity using a 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging assay and UV-vis spectroscopy. Histological evaluations confirmed the enhanced vascularization properties of coated samples after subcutaneous implantation.

CONCLUSION

Our findings suggest that ALG-rGO is a promising scaffold for accelerating the repair of damaged heart tissue.

Effect of graphene oxide nanoparticles on in vitro growth of Fragaria x ananassa (Cameron Highlands white Strawberry) and evaluation of genetic stability using DAMD and ISSR markers

Graphene oxide (GO) is a novel nanomaterial with distinct physical properties and significant biological applications. The use of GO in plant tissue culture offers several new properties and potential applications. This research is vital due to the growing need for innovative techniques to promote plant growth, improve plant productivity and mitigate challenges posed by environmental stressors. This study focused on the rare Cameron Highlands white strawberry plants (Fragaria x ananassa) and addressed issues such as callus production during direct shoot induction and hyperhydricity. The research aimed to investigate the effects of GO on the regeneration process and genetic stability of white strawberry plants and to use molecular markers to ensure that plants propagated in vitro are true to type. For this purpose, shoot tip explants were used and different concentrations of GO (0, 2.5, 5.0, 7.5, 10 mg/L) were added to the Murashige and Skoog (MS) medium for six weeks. The results showed that the optimum concentration for promoting the development of white strawberry seedlings was 7.5 mg/L of GO. The study also revealed that the addition of 7.5 mg/L GO in combination with 8 μM TDZ to the MS medium facilitated the induction of multiple shoots. Moreover, the clonal fidelity of the in vitro plants treated with GO showed a genetic similarity of over 97%. These results confirm that lower GO concentrations improve plant development and stability. Consequently, this nanomaterial has a positive effect on the growth of strawberry plants and is therefore well suited for strawberry tissue culture.

Regulation of astrocyte activity and immune response on graphene oxide-coated titanium by electrophoretic deposition

Introduction: Astrocytes play crucial role in modulating immune response in the damaged central nervous system. Numerous studies have investigated the relationship between immune responses in astrocytes and brain diseases. However, the potential application of nanomaterials for alleviating neuroinflammation induced by astrocytes remains unexplored. Method: In this study, we utilized electrophoretic deposition (EPD) to coat graphene oxide (GO) onto titanium (Ti) to enhance the bioactivity of Ti. Results: We confirmed that GO-Ti could improve cell adhesion and proliferation of astrocytes with upregulated integrins and glial fibrillary acidic protein (GFAP) expression. Moreover, we observed that astrocytes on GO-Ti exhibited a heightened immune response when exposed to lipopolysaccharide (LPS). Although pro-inflammatory cytokines increased, anti-inflammatory cytokines and brain-derived neurotrophic factors involved in neuroprotective effects were also augmented through nuclear localization of the yes-associated protein (YAP) and nuclear factor kappa B (NF-κB). Discussion: Taken together, GO-Ti could enhance the neuroprotective function of astrocytes by upregulating the expression of anti-inflammatory cytokines and neuroprotective factors with improved cell adhesion and viability. Consequently, our findings suggest that GO-Ti has the potential to induce neuroprotective effects by regulating cell activity.

Environmental biotechnology and the involving biological process using graphene-based biocompatible material

Biotechnology is a promising approach to environmental remediation but requires improvement in efficiency and convenience. The improvement of biotechnology has been illustrated with the help of biocompatible materials as biocarrier for environmental remediations. Recently, graphene-based materials (GBMs) have become promising materials in environmental biotechnology. To better illustrate the principle and mechanisms of GBM application in biotechnology, the comprehension of the biological response of microorganisms and enzymes when facing the GBMs is needed. The review illustrated distinct GBM-microbe/enzyme composites by providing the GBM-microbe/enzyme interaction and the determining factors. There are diverse GBM modifications for distinct biotechnology applications. Each of these methods and applications depends on the physicochemical properties of GBMs. The applications of these composites were mainly categorized as pollutant adsorption, anaerobic digestion, microbial fuel cells, and organics degradation. Where information was available, the strategies and mechanisms of GBMs in improving application efficacies were also demonstrated. In addition, the biological response, from microbial community changes, extracellular polymeric substances changes to biological pathway alteration, may become important in the application of these composites. Furthermore, we also discuss challenges facing the environmental application of GBMs, considering their fate and toxicity in the ecosystem, and offer potential solutions. This research significantly enhances our comprehension of the fundamental principles, underlying mechanisms, and biological pathways for the in-situ utilization of GBMs.

Nanomaterials Modulating the Fate of Dental-Derived Mesenchymal Stem Cells Involved in Oral Tissue Reconstruction: A Systematic Review

The critical challenges in repairing oral soft and hard tissue defects are infection control and the recovery of functions. Compared to conventional tissue regeneration methods, nano-bioactive materials have become the optimal materials with excellent physicochemical properties and biocompatibility. Dental-derived mesenchymal stem cells (DMSCs) are a particular type of mesenchymal stromal cells (MSCs) with great potential in tissue regeneration and differentiation. This paper presents a review of the application of various nano-bioactive materials for the induction of differentiation of DMSCs in oral and maxillofacial restorations in recent years, outlining the characteristics of DMSCs, detailing the biological regulatory effects of various nano-materials on stem cells and summarizing the material-induced differentiation of DMSCs into multiple types of tissue-induced regeneration strategies. Nanomaterials are different and complementary to each other. These studies are helpful for the development of new nanoscientific research technology and the clinical transformation of tissue reconstruction technology and provide a theoretical basis for the application of nanomaterial-modified dental implants. We extensively searched for papers related to tissue engineering bioactive constructs based on MSCs and nanomaterials in the databases of PubMed, Medline, and Google Scholar, using keywords such as "mesenchymal stem cells", "nanotechnology", "biomaterials", "dentistry" and "tissue regeneration". From 2013 to 2023, we selected approximately 150 articles that align with our philosophy.

Fabricating a low-temperature synthesized graphene-cellulose acetate-sodium alginate scaffold for the generation of ovarian cancer spheriod and its drug assessment

3D cell culture can mimic tumor pathophysiology, which reflects cellular morphology and heterogeneity, strongly influencing gene expression, cell behavior, and intracellular signaling. It supports cell-cell and cell-matrix interaction, cell attachment, and proliferation, resulting in rapid and reliable drug screening models. We have generated an ovarian cancer spheroid in interconnected porous scaffolds. The scaffold is fabricated using low-temperature synthesized graphene, cellulose acetate, and sodium alginate. Graphene nanosheets enhance cell proliferation and aggregation, which aids in the formation of cancer spheroids. The spheroids are assessed after day 7 and 14 for the generation of reactive oxygen species (ROS), expression of the hypoxia inducing factor (HIF-1⍺) and vascular endothelial growth factor (VEGF). Production of ROS was observed due to the aggregated tumor mass, and enhanced production of HIF-1⍺ and VEGF results from a lack of oxygen and nutrition. Furthermore, the efficacy of anticancer drug doxorubicin at varying concentrations is assessed on ovarian cancer spheroids by studying the expression of caspase-3/7 at day 7 and 14. The current findings imply that the graphene-cellulose-alginate (GCA) scaffold generates a reliable ovarian cancer spheroid model to test the efficacy of the anticancer drug.

Graphene as a nano-delivery vehicle in agriculture - current knowledge and future prospects

Graphene has triggered enormous interest in, and exploration of, its applications in diverse areas of science and technology due to its unique properties. While graphene has displayed great potential as a nano-delivery system for drugs and biomolecules in biomedicine, its application as a nanocarrier in agriculture has only begun to be explored. Conventional fertilizers and agricultural delivery systems have a number of disadvantages, such as: fast release of the active ingredient, low delivery efficiency, rapid degradation and low stability that often leads to their over-application and consequent environmental problems. Advanced nano fertilizers with high carrier efficiency and slow and controlled release are now considered the gold standard for promoting agricultural sustainability while protecting the environment. Graphene's attractive properties include large surface area, chemical stability, mechanical stability, tunable surface chemistry and low toxicity making it a promising material on which to base agricultural delivery systems. Recent research has demonstrated considerable success in the use of graphene for agricultural applications, including its utilization as a delivery vehicle for plant nutrients and crop protection agents, as well as in post-harvest management of crops. This review, therefore, presents a comprehensive overview of the current status of graphene-based nanocarriers in agriculture. Additionally, the review outlines the surface functionalization methods used for effective molecular delivery, various strategies for nano-vehicle design and the underlying features necessary for a graphene-based agro-delivery system. Finally, the review discusses directions for further research in optimization of graphene-based nanocarriers.

Effect of foliar application of nanoparticles on growth, physiology, and antioxidant enzyme activities of lettuce (Lactuca sativa L.) plants under cadmium toxicity

Nanotechnology has attracted the interest of scientists due to its wide range of application specifically in agriculture. Nanoparticles (NPs) may act as a promising materials to alleviate cadmium (Cd) stress in plants. This study aims to assess the impact of multiple nanoparticles including nSiO2 (50 mg L-1:100 mg L-1), nTiO2 (20 mg L-1:60 mg L-1), nZnO (50 mg L-1:100 mg L-1), nFe3O4 (100 mg L-1:200 mg L-1), nCuO (50 mg L-1:100 mg L-1), and nCeO2 (50 mg L-1:100 mg L-1) in combination with CdCl2 (5 µM) to mitigate Cd toxicity in lettuce through foliar application in hydroponic solution. Current findings indicate that foliar application of nSiL + Cd (50 mg L-1), nZnL + Cd (50 mg L-1), and nTiL + Cd (20 mg L-1) is more effective in improving growth, biomass, root architecture, and elevated photosynthetic efficiency, which might be attributed to the increasing uptake of essential micronutrient (K, Mg, Ca, Fe, Zn) under Cd stress. Similarly, treatment with nanoparticles leads to reduced accumulation of ROS and MDA in lettuce, while enhancing the SOD, POD, CAT, and APX activities. The results showed that nanoparticles have high tolerance against Cd as depicted by the inhibition in Cd accumulation by 3.2-58% and 10-72% in roots as well as edible parts of lettuce, respectively. In addition, Cd alone reduces the morphological traits, antioxidant enzyme activity, and photosynthetic activity, while increasing the ROS, MDA, and Cd accumulation in lettuce. This comprehensive study suggests the role of nanoparticles in reducing Cd toxicity in lettuce, signifying their importance as stress mitigation agents. However, long-term pot, priming, and field trials are needed to identify the optimal nanoparticle for the lettuce under variable environmental conditions.

3D-printed scaffolds with 2D hetero-nanostructures and immunomodulatory cytokines provide pro-healing microenvironment for enhanced bone regeneration

Three-dimensional (3D) printing technology is driving forward the progresses of various engineering fields, including tissue engineering. However, the pristine 3D-printed scaffolds usually lack robust functions in stimulating desired activity for varied regeneration applications. In this study, we combined the two-dimensional (2D) hetero-nanostructures and immuno-regulative interleukin-4 (IL-4) cytokines for the functionalization of 3D-printed scaffolds to achieve a pro-healing immuno-microenvironment for optimized bone injury repair. The 2D hetero-nanostructure consists of graphene oxide (GO) layers, for improved cell adhesion, and black phosphorous (BP) nanosheets, for the continuous release of phosphate ions to stimulate cell growth and osteogenesis. In addition, the 2D hetero-nanolayers facilitated the adsorption of large content of immuno-regulative IL-4 cytokines, which modulated the polarization of macrophages into M2 phenotype. After in vivo implantation in rat, the immuno-functioned 3D-scaffolds achieved in vivo osteo-immunomodulation by building a pro-healing immunological microenvironment for better angiogenesis and osteogenesis in the defect area and thus facilitated bone regeneration. These results demonstrated that the immuno-functionalization of 3D-scaffolds with 2D hetero-nanostructures with secondary loading of immuno-regulative cytokines is an encouraging strategy for improving bone regeneration.

Effect of graphene on soybean root colonization by Bradyrhizobium strains

Legume crops such as soybean obtain a large portion of their nitrogen nutrition through symbiotic nitrogen fixation by diazotrophic rhizobia bacteria in root nodules. However, nodule occupancy by low-capacity nitrogen-fixing rhizobia can lead to lower-than-optimal levels of nitrogen fixation. Seed/root coating with engineered materials such as graphene-carrying biomolecules that may promote specific attraction/attachment of desirable bacterial strains is a potential strategy that can help overcome this rhizobia competition problem. As a first step towards this goal, we assessed the impact of graphene on soybean and Bradyrhizobium using a set of growth, biochemical, and physiological assays. Three different concentrations of graphene were tested for toxicity in soybean (50, 250, and 1,000 mg/l) and Bradyrhizobia (25, 50, and 100 mg/l). Higher graphene concentrations (250 mg/l and 1,000 mg/l) promoted seed germination but slightly delayed plant development. Spectrometric and microscopy assays for hydrogen peroxide and superoxide anion suggested that specific concentrations of graphene led to higher levels of reactive oxygen species in the roots. In agreement, these roots also showed higher activities of antioxidant enzymes, catalase, and ascorbate peroxidase. Conversely, no toxic effects were detected on Bradyrhizobia treated with graphene, and neither did they have higher levels of reactive oxygen species. Graphene treatments at 250 mg/l and 1,000 mg/l significantly reduced the number of nodules, but rhizobia infection and the overall nitrogenase activity were not affected. Our results show that graphene can be used as a potential vehicle for seed/root treatment.

Nanobio Interface Between Proteins and 2D Nanomaterials

Two-dimensional (2D) nanomaterials have significantly contributed to recent advances in material sciences and nanotechnology, owing to their layered structure. Despite their potential as multifunctional theranostic agents, the biomedical translation of these materials is limited due to a lack of knowledge and control over their interaction with complex biological systems. In a biological microenvironment, the high surface energy of nanomaterials leads to diverse interactions with biological moieties such as proteins, which play a crucial role in unique physiological processes. These interactions can alter the size, surface charge, shape, and interfacial composition of the nanomaterial, ultimately affecting its biological activity and identity. This review critically discusses the possible interactions between proteins and 2D nanomaterials, along with a wide spectrum of analytical techniques that can be used to study and characterize such interplay. A better understanding of these interactions would help circumvent potential risks and provide guidance toward the safer design of 2D nanomaterials as a platform technology for various biomedical applications.

Kinetic simulation study of femtosecond laser processing of graphene oxide: first-principles

CONTEXT

Organic-inorganic nanoparticles have received extensive attention in various fields due to their unique physicochemical properties and biological activities. Among these nanoparticles, graphene oxide (GO) has emerged as a promising material, and thus, its application in biomedical fields is of great interest. Coating graphene oxide on the surface of implants can enhance its properties such as antibacterial and cell proliferation promotion, but the osteogenic properties of graphene oxide coating need further improvement, and the chance of acute inflammation triggered by local reactive oxygen species accumulation needs to be reduced. High-precision modulation of graphene oxide surface micro/nanomorphology and chemical composition can be achieved using femtosecond laser processing technology to improve its performance while also reducing the oxygen content of the graphene oxide surface to some extent. In this paper, the properties of graphene oxide were investigated by kinetic simulations based on the first-principle. The results show that the band gap of graphene oxide changes from 0.386 to 0.021 eV; the work function changes from 4.882 to 4.64 eV; the size and number of peaks in the radial distribution function decreases; and the intensity of the scatter X-ray peak becomes smaller under the action of femtosecond laser, indicating that the oxygen-containing functional groups on the surface of graphene oxide are disrupted, which provides a basis for its potential application in the medical field.

METHODS

To investigate the properties of graphene oxide, SEM, XPS, Raman, and FTIR characterizations were first used to determine the oxygen-containing functional group species on the surface of graphene oxide. The structural model of graphene oxide was then modeled for density flooding theory (DFT) simulations using Biovia Materials Studio software, which was implemented in the CASTEP code. Our DFT calculations were performed using the generalized gradient approximation (GGA) as parameterized by the Perdew-Burke Ernzerhof (PBE) exchange-correlation functional. Additionally, we employed the norm-conserving pseudopotential to treat core electrons.

Cost-effective one-spot hydrothermal synthesis of graphene oxide nanoparticles for wastewater remediation: AI-enhanced approach for transition metal oxides

This investigation presents a cost-efficient hydrothermal synthesis technique for producing graphene oxide nanoparticles (GO-NPs) that exhibit promising potential in wastewater treatment. The synthesis process involves a facile and expandable hydrothermal reactor that can be regulated using an AI-empowered methodology. The generated GO-NPs were characterised using X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, and transmission electron microscopy (TEM), confirming their successful synthesis and high quality. The high degree of crystallinity observed in the GO-NPs can be attributed to the favourable reaction conditions facilitated by the hydrothermal synthesis. The TEM analysis showed that the GO-NPs had a homogeneous dispersion pattern and a consistent size distribution of approximately 10 nm. Carboxylation was employed to functionalize the GO-NPs, enhancing their reactivity towards diverse contaminants present in wastewater. The remediation potential of the GO-NPs for transition metal oxides, which are frequently found in wastewater, was assessed. The GO-NPs exhibited notable efficacy in remediating the transition metal oxides that were subjected to testing. The heightened efficacy of remediation can be attributed to the substantial surface area and elevated reactivity of the GO-NPs, in addition to their functionalization using carboxylic groups. The cost-effective and efficient synthesis method, coupled with the high remediation potential of the GO-NPs, makes them a highly promising contender for employment in wastewater remediation applications. The use of AI in regulating the hydrothermal synthesis procedure enables accurate manipulation of the reaction parameters, thereby augmenting the quality and uniformity of the resultant GO-NPs. The proposed method exhibits scalability potential for large-scale production of GO-NPs, presenting a viable remedy for the challenges associated with wastewater remediation.

Theoretical studies of phosphorene as a drug delivery nanocarrier for fluorouracil

The interactions between phosphorene nanosheets (PNSs) and 5-fluorouracil (FLU) were explored using the density functional theory (DFT) method and molecular dynamics (MD) simulations. DFT calculations were performed utilizing M06-2X functional and the 6-31G(d,p) basis set in both gas and solvent phases. Results showed that the FLU molecule is adsorbed horizontally on the PNS surface with an adsorption energy (Eads) of -18.64 kcal mol-1. The energy gap (Eg) between the highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO, respectively) of PNS remains constant after the adsorption process. The adsorption behavior of PNS is not affected by carbon and nitrogen doping. The dynamical behavior of PNS-FLU was studied at T = 298, 310, and 326 K reminiscent of room temperature, body temperature, and temperature of the tumor after exposure to 808 nm laser radiation, respectively. The D value decreases significantly after the equilibration of all systems so that the equilibrated value of D is about 1.1 × 10-6, 4.0 × 10-8, and 5.0 × 10-9 cm2 s-1 at T = 298, 310, and 326 K, respectively. About 60 FLU molecules can be adsorbed on both sides of each PNS, indicating its high loading capacity. PMF calculations demonstrated that the release of FLU from PNS is not spontaneous, which is favorable from a sustained drug delivery point of view.

Understanding the role of graphene oxide in affecting PAHs biodegradation by microorganisms: An integrated analysis using 16SrRNA, metatranscriptomic, and metabolomic approaches

Graphene oxide (GO)-promoted microbial degradation technology is considered an important strategy to eliminate polycyclic aromatic hydrocarbons (PAHs) in the environment; however, the mechanism by which GO affects microbial degradation of PAHs has not been fully studied. Thus, this study aimed to analyze the effect of GO-microbial interaction on PAHs degradation at the microbial community structure, community gene expression, and metabolic levels using multi-omics combined technology. We treated PAHs-contaminated soil samples with different concentrations of GO and analyzed the soil samples for microbial diversity after 14 and 28 days. After a short exposure, GO reduced the diversity of soil microbial community but increased potential degrading microbial abundance, promoting PAHs biodegradation. This promotion effect was further influenced by the GO concentration. In a short period of time, GO upregulated the expression of genes involved in microbial movement (flagellar assembly), bacterial chemotaxis, two-component system, and phosphotransferase system in the soil microbial community and increased the probability of microbial contact with PAHs. Biosynthesis of amino acids and carbon metabolism of microorganisms were accelerated, thereby increasing the degradation of PAHs. With the extension of time, the degradation of PAHs stagnated, which may be due to the weakened stimulation of GO on microorganisms. The results showed that screening specific degrading microorganisms, increasing the contact area between microorganisms and PAHs, and prolonging the stimulation of GO on microorganisms were important means to improve the biodegradation efficiency of PAHs in soil. This study elucidates how GO affects microbial PAHs degradation and provides important insights for the application of GO-assisted microbial degradation technology.

Bacillussp. based nano-bio hybrids for efficient water remediation

Macroalgae are a diverse group of primary producers that offer indispensable ecosystem services towards bacterial colonization and proliferation in aquatic biomes. Macroalgae/bacteria interactions are complex in natural biomes and contribute mutually to their growth and biotechnological outcomes. Most findings on macroalgae-associated bacteria and their secreted enzymes have largely been limited to nutraceutical applications. Here, in this study, we demonstrate and investigate the growth of Bacillus sp. (macroalgae-associated bacteria) with the substitution of its associated macroalgae (Gracilaria corticata) on graphene oxide (GO). The findings indicated that the presence of wrinkles of GO nanosheets resulted in cell proliferation and adherence without causing mechanical damage to the cell membrane. Furthermore, the assembly of GO-marine bacteria was explored for organic pollutant treatment using methylene blue (MB) as a model dye. The degradation results suggest the breakdown of MB into non-toxic byproducts as suggested by the phytotoxicity assay.

A tissue-engineered neural interface with photothermal functionality

Neural interfaces are well-established as a tool to understand the behaviour of the nervous system via recording and stimulation of living neurons, as well as serving as neural prostheses. Conventional neural interfaces based on metals and carbon-based materials are generally optimised for high conductivity; however, a mechanical mismatch between the interface and the neural environment can significantly reduce long-term neuromodulation efficacy by causing an inflammatory response. This paper presents a soft composite material made of gelatin methacryloyl (GelMA) containing graphene oxide (GO) conjugated with gold nanorods (AuNRs). The soft hydrogel presents stiffness within the neural environment range of modulus below 5 kPa, while the AuNRs, when exposed to light in the near infrared range, provide a photothermal response that can be used to improve the spatial and temporal precision of neuromodulation. These favourable properties can be maintained at safer optical power levels when combined with electrical stimulation. In this paper we provide mechanical and biological characterization of the optical activity of the GO-AuNR composite hydrogel. The optical functionality of the material has been evaluated via photothermal stimulation of explanted rat retinal tissue. The outcomes achieved with this study encourage further investigation into optical and electrical costimulation parameters for a range of biomedical applications.

Development of sustainable strontium ferrite graphene nanocomposite for highly effective catalysis and antimicrobial activity

Graphene oxide (GO) has layered structure with carbon atoms that are highly coated with oxygen-containing groups, increasing the interlayer distance while simultaneously making hydrophilic atomic-thick layers. It is exfoliated sheets that only have one or a few layers of carbon atoms. In our work, Strontium Ferrite Graphene Composite (SF@GOC) has been synthesized and thoroughly characterized by physico-chemical methods like XRD, FTIR, SEM-EDX, TEM, AFM, TGA and Nitrogen adsorption desorption analysis. A very few catalysts have been manufactured so far that are capable of degrading Eosin-Y and Orange (II) dyes in water by heterogeneous catalytic method. The current study offers an overview of the recyclable nanocomposite SF@GOC used in mild reaction conditions to breakdown the hazardous water pollutant dyes Eosin-Y (96.2%) and Orange (II) (98.7%). The leaching experiment has demonstrated that the use of the transition metals strontium and iron have not result in any secondary contamination. Moreover, antibacterial and antifungal assay have been investigated. SF@GOC has shown greater activity with bacterial and fungal species while compared with GO. FESEM analysis shows that the bactericidal mechanism for SF@GOC is same in both gram-negative bacteria. The difference in the antifungal activity among the candida strains can be correlated with the movement of ions release (slower and faster) of synthesized nanoscrolls in SF@GOC. In comparison to previous reports, this new environmentally safe and novel catalyst showed substantial degrading activity. It can also be applied to new multifunctional processes such as in the fields of composite materials, solar energy, heterogeneous catalysis and biomedical applications.

Graphene oxide exposure alters gut microbial community composition and metabolism in an in vitro human model

Graphene oxide (GO) nanomaterials have unique physicochemical properties that make them highly promising for biomedical, environmental, and agricultural applications. There is growing interest in the use of GO and extensive in vitro and in vivo studies have been conducted to assess its nanotoxicity. Although it is known that GO can alter the composition of the gut microbiota in mice and zebrafish, studies on the potential impacts of GO on the human gut microbiome are largely lacking. This study addresses an important knowledge gap by investigating the impact of GO exposure- at low (25 mg/L) and high (250 mg/L) doses under both fed (nutrient rich) and fasted (nutrient deplete) conditions- on the gut microbial communitys' structure and function, using an in vitro model. This model includes simulated oral, gastric, small intestinal phase digestion of GO followed by incubation in a colon bioreactor. 16S rRNA amplicon sequencing revealed that GO exposure resulted in a restructuring of community composition. 25 mg/L GO induced a marked decrease in the Bacteroidota phylum and increased the ratio of Firmicutes to Bacteroidota (F/B). Untargeted metabolomics on the supernatants indicated that 25 mg/L GO impaired microbial utilization and metabolism of substrates (amino acids, carbohydrate metabolites) and reduced production of beneficial microbial metabolites such as 5-hydroxyindole-3-acetic acid and GABA. Exposure to 250 mg/L GO resulted in community composition and metabolome profiles that were very similar to the controls that lacked both GO and digestive enzymes. Differential abundance analyses revealed that 3 genera from the phylum Bacteroidota (Bacteroides, Dysgonomonas, and Parabacteroides) were more abundant after 250 mg/L GO exposure, irrespective of feed state. Integrative correlation network analysis indicated that the phylum Bacteroidota showed strong positive correlations to multiple microbial metabolites including GABA and 3-indoleacetic acid, are much larger number of correlations compared to other phyla. These results show that GO exposure has a significant impact on gut microbial community composition and metabolism at both low and high GO concentrations.

Graphene-Related Nanomaterials for Biomedical Applications

This paper builds on the context and recent progress on the control, reproducibility, and limitations of using graphene and graphene-related materials (GRMs) in biomedical applications. The review describes the human hazard assessment of GRMs in in vitro and in vivo studies, highlights the composition-structure-activity relationships that cause toxicity for these substances, and identifies the key parameters that determine the activation of their biological effects. GRMs are designed to offer the advantage of facilitating unique biomedical applications that impact different techniques in medicine, especially in neuroscience. Due to the increasing utilization of GRMs, there is a need to comprehensively assess the potential impact of these materials on human health. Various outcomes associated with GRMs, including biocompatibility, biodegradability, beneficial effects on cell proliferation, differentiation rates, apoptosis, necrosis, autophagy, oxidative stress, physical destruction, DNA damage, and inflammatory responses, have led to an increasing interest in these regenerative nanostructured materials. Considering the existence of graphene-related nanomaterials with different physicochemical properties, the materials are expected to exhibit unique modes of interactions with biomolecules, cells, and tissues depending on their size, chemical composition, and hydrophil-to-hydrophobe ratio. Understanding such interactions is crucial from two perspectives, namely, from the perspectives of their toxicity and biological uses. The main aim of this study is to assess and tune the diverse properties that must be considered when planning biomedical applications. These properties include flexibility, transparency, surface chemistry (hydrophil-hydrophobe ratio), thermoelectrical conductibility, loading and release capacity, and biocompatibility.

Transcriptome Analysis Reveals the Growth Promotion Mechanism of Enteropathogenic Escherichia coli Induced by Black Phosphorus Nanosheets

With the extensive production and application of black phosphorus (BP) nanosheets, release to the environment is inevitable, which raises concerns about the fate and effects of this two-dimensional (2D) material on sensitive receptors such as environmental microbes. Although the bacterial toxicity of BP nanosheets has been demonstrated, whether the biological response differs in pathogenic and nonpathogenic strains of a microorganism is unknown. Here, enteropathogenic Escherichia coli (EPEC) and nonpathogenic Escherichia coli DH5α (E. coli DH5α), Escherichia coli k12 (E. coli k12), and Bacillus tropicus (B. tropicus) are used to comparatively study the microbial toxicity of BP nanosheets. Upon exposure to BP nanosheets across a range of doses from 10 to 100 μg mL^-1 for 12 h, EPEC experienced enhanced growth and E. coli DH5α and E. coli k12 were not affected, whereas B. tropicus exhibited clear toxicity. By combining transcriptome sequencing, proteome analysis, and other sensitive biological techniques, the mechanism of BP-induced growth promotion for EPEC was uncovered. Briefly, BP nanosheets activate the antioxidation system to resist oxidative stress, promote protein synthesis and secretion to attenuate membrane damage, enhance the energy supply, and activate growth-related pathways. None of these impacts were evident with nonpathogenic strains. By describing the mechanism of strain-dependent microbial effects, this study not only highlights the potential risks of BP nanosheets to the environment and to human health but also calls attention to the importance of model strain selection when evaluating the hazard and toxicity of emerging nanomaterials.

An Overview on Exploitation of Graphene-Based Membranes: From Water Treatment to Medical Industry, Including Recent Fighting against COVID-19

Graphene and its derivatives have lately been the subject of increased attention for different environmental applications of membrane technology such as water treatment and air filtration, exploiting their antimicrobial and antiviral activity. They are interesting candidates as membrane materials for their outstanding mechanical and chemical stability and for their thin two-dimensional (2D) nanostructure with potential pore engineering for advanced separation. All these applications have evolved and diversified from discovery to today, and now graphene and graphene derivatives also offer fascinating opportunities for the fight against infective diseases such as COVID-19 thanks to their antimicrobial and antiviral properties. This paper presents an overview of graphene-based 2D materials, their preparation and use as membrane material for applications in water treatment and in respiratory protection devices.