Bactericidal Effect and Cytotoxicity of Graphene Oxide/Silver Nanocomposites.

To tackle the proliferation of pathogenic microorganisms without relying on antibiotics, innovative materials boasting antimicrobial properties have been engineered. This study focuses on the development of graphene oxide/silver (GO/Ag) nanocomposites, derived from partially reduced graphene oxide adorned with silver nanoparticles. Various nanocomposites with different amounts of silver (GO/Ag-1, GO/Ag-2, GO/Ag-3, and GO/Ag-4) were synthesized, and their antibacterial efficacy was systematically studied. The silver nanoparticles were uniformly deposited on the partially reduced graphene oxide surface, exhibiting spherical morphologies with an average size of 25 nm. The nanocomposites displayed potent antibacterial properties against both gram-positive bacteria (S. aureus and B. subtilis) and gram-negative bacteria (E. coli and S. enterica) as confirmed by minimum inhibition concentration (MIC) studies and time-dependent experiments. The optimal MIC for Gram-positive bacteria was 62.5 µg/mL and for Gram-negative bacteria was 125 µg/mL for the GO/Ag nanocomposites. Bacterial cells that encountered the nanocomposite films exhibited significantly greater inhibitory effects compared to those exposed to conventional antibacterial materials. Furthermore, the cytotoxicity of these nanocomposites was assessed using human epithelial cells (HEC), revealing that GO/Ag-1 and GO/Ag-2 exhibited lower toxicity levels toward HEC and remained compatible even at higher dilution rates. This study underscores the potential of GO/Ag-based nanocomposites as versatile materials for antibacterial applications, particularly as biocompatible wound dressings, offering promising prospects for wound healing and infection control.

Carbon Nanomaterials for Plant Priming through Mechanostimulation: Emphasizing the Role of Shape.

The use of nanomaterials to improve plant immunity for sustainable agriculture is gaining increasing attention; yet, the mechanisms involved remain unclear. In contrast to metal-based counterparts, carbon-based nanomaterials do not release components. Determining how these carbon-based nanomaterials strengthen the resistance of plants to diseases is essential as well as whether shape influences this process. Our study compared single-walled carbon nanotubes (SWNTs) and graphene oxide (GO) infiltration against the phytopathogen Pseudomonas syringae pv tomato DC3000. Compared with plants treated with GO, plants primed with SWNTs showed a 29% improvement in the pathogen resistance. Upon nanopriming, the plant displayed wound signaling with transcriptional regulation similar to that observed under brushing-induced mechanostimulation. Compared with GO, SWNTs penetrated more greatly into the leaf and improved transport, resulting in a heightened wound response; this effect resulted from the tubular structure of SWNTs, which differed from the planar form of GO. The shape effect was further demonstrated by wrapping SWNTs with bovine serum albumin, which masked the sharp edges of SWNTs and resulted in a significant decrease in the overall plant wound response. Finally, we clarified how the local wound response led to systemic immunity through increased calcium ion signaling in distant plant areas, which increased the antimicrobial efficacy. In summary, our systematic investigation established connections among carbon nanomaterial priming, mechanostimulation, and wound response, revealing recognition patterns in plant immunity. These findings promise to advance nanotechnology in sustainable agriculture by strengthening plant defenses, enhancing resilience, and reducing reliance on traditional chemicals.

Graphene oxide films as a novel tool for the modulation of myeloid-derived suppressor cell activity in the context of multiple sclerosis.

Despite the pharmacological arsenal approved for Multiple Sclerosis (MS), there are treatment-reluctant patients for whom cell therapy appears as the only therapeutic alternative. Myeloid-derived suppressor cells (MDSCs) are immature cells of the innate immunity able to control the immune response and to promote oligodendroglial differentiation in the MS animal model experimental autoimmune encephalomyelitis (EAE). However, when isolated and cultured for cell therapy purposes, MDSCs lose their beneficial immunomodulatory properties. To prevent this important drawback, culture devices need to be designed so that MDSCs maintain a state of immaturity and immunosuppressive function similar to that exerted in the donor organism. With this aim, we select graphene oxide (GO) as a promising candidate as it has been described as a biocompatible nanomaterial with the capacity to biologically modulate different cell types, yet its immunoactive potential has been poorly explored to date. In this work, we have fabricated GO films with two distintive redox and roughness properties and explore their impact in MDSC culture right after isolation. Our results show that MDSCs isolated from immune organs of EAE mice maintain an immature phenotype and highly immunosuppressive activity on T lymphocytes after being cultured on highly-reduced GO films (rGO200) compared to those grown on conventional glass coverslips. This immunomodulation effect is depleted when MDSCs are exposed to slightly rougher and more oxidized GO substrates (rGO90), in which cells experience a significant reduction in cell size associated with the activation of apoptosis. Taken together, the exposure of MDSCs to GO substrates with different redox state and roughness is presented as a good strategy to control MDSC activity in vitro. The versatility of GO nanomaterials in regards to the impact of their physico-chemical properties in immunomodulation opens the door to their selective therapeutic potential for pathologies where MDSCs need to be enhanced (MS) or inhibited (cancer).

Impact of the Reduction Time-Dependent Electrical Conductivity of Graphene Nanoplatelet-Coated Aligned Bombyx mori Silk Scaffolds on Electrically Stimulated Axonal Growth.

Graphene-based nanomaterials, renowned for their outstanding electrical conductivity, have been extensively studied as electroconductive biomaterials (ECBs) for electrically stimulated tissue regeneration. However, using eco-friendly reducing agents like l-ascorbic acid (l-Aa) can result in lower conductive properties in these ECBs, limiting their full potential for smooth charge transfer in living tissues. Moreover, creating a flexible biomaterial scaffold using these materials that accurately mimics a specific tissue microarchitecture, such as nerves, poses additional challenges. To address these issues, this study developed a microfibrous scaffold of Bombyx mori (Bm) silk fibroin uniformly coated with graphene nanoplatelets (GNPs) through a vacuum coating method. The scaffold's electrical conductivity was optimized by varying the reduction period using l-Aa. The research systematically investigated how different reduction periods impact scaffold properties, focusing on electrical conductivity and its significance on electrically stimulated axonal growth in PC12 cells. Results showed that a 48 h reduction significantly increased surface electrical conductivity by 100-1000 times compared to a shorter or no reduction process. l-Aa contributed to stabilizing the reduced GNPs, demonstrated by a slow degradation profile and sustained conductivity even after 60 days in a proteolytic environment. ß (III) tubulin immunostaining of PC12 cells on varied silk:GNP scaffolds under pulsed electrical stimulation (ES, 50 Hz frequency, 1 ms pulse width, and amplitudes of 100 and 300 mV/cm) demonstrates accelerated axonal growth on scaffolds exhibiting higher conductivity. This is supported by upregulated intracellular Ca2+ dynamics immediately after ES on the scaffolds with higher conductivity, subjected to a prolonged reduction period. The study showcases a sustainable reduction approach using l-Aa in combination with natural Bm silk fibroin to create a highly conductive, mechanically robust, and stable silk:GNP-based aligned fibrous scaffold. These scaffolds hold promise for functional regeneration in electrically excitable tissues such as nerves, cardiac tissue, and muscles.

Reduced Graphene Oxide Fibers Combined with Electrical Stimulation Promote Peripheral Nerve Regeneration.

Background: The treatment of long-gap peripheral nerve injury (PNI) is still a substantial clinical problem. Graphene-based scaffolds possess extracellular matrix (ECM) characteristic and can conduct electrical signals, therefore have been investigated for repairing PNI. Combined with electrical stimulation (ES), a well performance should be expected. We aimed to determine the effects of reduced graphene oxide fibers (rGOFs) combined with ES on PNI repair in vivo. Methods: rGOFs were prepared by one-step dimensionally confined hydrothermal strategy (DCH). Surface characteristics, chemical compositions, electrical and mechanical properties of the samples were characterized. The biocompatibility of the rGOFs were systematically explored both in vitro and in vivo. Total of 54 Sprague-Dawley (SD) rats were randomized into 6 experimental groups: a silicone conduit (S), S+ES, S+rGOFs-filled conduit (SGC), SGC+ES, nerve autograft, and sham groups for a 10-mm sciatic defect. Functional and histological recovery of the regenerated sciatic nerve at 12 weeks after surgery in each group of SD rats were evaluated. Results: rGOFs exhibited aligned micro- and nano-channels with excellent mechanical and electrical properties. They are biocompatible in vitro and in vivo. All 6 groups exhibited PNI repair outcomes in view of neurological and morphological recovery. The SGC+ES group achieved similar therapeutic effects as nerve autograft group (P > 0.05), significantly outperformed other treatment groups. Immunohistochemical analysis showed that the expression of proteins related to axonal regeneration and angiogenesis were relatively higher in the SGC+ES. Conclusion: The rGOFs had good biocompatibility combined with excellent electrical and mechanical properties. Combined with ES, the rGOFs provided superior motor nerve recovery for a 10-mm nerve gap in a murine acute transection injury model, indicating its excellent repairing ability. That the similar therapeutic effects as autologous nerve transplantation make us believe this method is a promising way to treat peripheral nerve defects, which is expected to guide clinical practice in the future.

Graphene promotes the growth of Vigna angularis by regulating the nitrogen metabolism and photosynthesis.

Graphene has promising applications in agriculture and forestry. In the current study, six different concentrations of graphene (0mg/L, 0.01mg/L, 0.10mg/L, 1.00mg/L, 10.00mg/L, and 100.00mg/L) were used to investigate its effect on the growth and development of V. angularis plants in soil culture. The results showed that the group treated with 1.00mg/L graphene (G-1) had significantly increased plant height (19.86%), stem diameter (24.33%), and leaf area (13.69%), compared to the control group (CK). Moreover, all concentrations of graphene had positive effects on the total root length, total root surface area, and the number of root tips of V. angularis. Compared to the CK group, the G-1 group had significantly increased leaf water potential (37.89%), leaf conductivity (2.25%), and SOD, POD, and CAT activities (47.67%, 35.22%, and 199.3%, respectively). The G-1 group also showed improved leaf net photosynthetic rate, chlorophyll content, and soluble sugar content (51.28%, 24.25%, and 38.35%, respectively), compared to the CK group. Additionally, 1.00mg/L graphene led to a 23.88% increase in the podding rate and a 17.04% increase in the yield of V. angularis plants. The rhizosphere soil of V. angularis treated with 1.00mg/L graphene had a 25.14% increase in hydrolyzable nitrogen content and a 66.67% increase in available phosphorus content. RNA-seq data indicated that 1.00mg/L graphene induced the expression of photosynthesis and nitrogen transmembrane transport genes, including ATP synthase subunit b, photosystem I reaction center subunit XI, photosystem I reaction center subunit IV A, ferredoxin, and psbP-like protein 1, as well as genes for photosynthesis antenna proteins, glutamine synthetase, glutamate dehydrogenase 1, cyanate hydratase, protein fluG-like, and NRT1/PTR family, suggesting that graphene promoted the growth and development of V. angularis by enhancing the photosynthesis and nitrogen metabolism processes in V. angularis plants. Our results indicated that a suitable concentration of graphene could significantly promote the growth of V. angularis plants in soil.

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.

Nanostructured Coatings Based on Graphene Oxide for the Management of Periprosthetic Infections.

To modulate the bioactivity and boost the therapeutic outcome of implantable metallic devices, biodegradable coatings based on polylactide (PLA) and graphene oxide nanosheets (nGOs) loaded with Zinforo™ (Zin) have been proposed in this study as innovative alternatives for the local management of biofilm-associated periprosthetic infections. Using a modified Hummers protocol, high-purity and ultra-thin nGOs have been obtained, as evidenced by X-ray diffraction (XRD) and transmission electron microscopy (TEM) investigations. The matrix-assisted pulsed laser evaporation (MAPLE) technique has been successfully employed to obtain the PLA-nGO-Zin coatings. The stoichiometric and uniform transfer was revealed by infrared microscopy (IRM) and scanning electron microscopy (SEM) studies. In vitro evaluation, performed on fresh blood samples, has shown the excellent hemocompatibility of PLA-nGO-Zin-coated samples (with a hemolytic index of 1.15%), together with their anti-inflammatory ability. Moreover, the PLA-nGO-Zin coatings significantly inhibited the development of mature bacterial biofilms, inducing important anti-biofilm efficiency in the as-coated samples. The herein-reported results evidence the promising potential of PLA-nGO-Zin coatings to be used for the biocompatible and antimicrobial surface modification of metallic implants.

Bone marrow-inspired hydrogel/graphene composite scaffolds to support in vitro expansion of hematopoietic stem cells.

Hematopoietic stem cell (HSC) expansion offers a key strategy to address the source limitation and donor shortages of HSCs for the treatment of various blood disorders. Specific remodeling of the complex bone marrow microenvironment that contributes to efficient in vitro expansion of HSCs remains challenging. Here, inspired by the regions with different stiffness levels in the bone marrow niche, a three dimensional (3D) bone marrow-mimicking composite scaffold created based on gelatin-hyaluronic acid (Gel-HA) hydrogels and graphene foams (GFs) was engineered to support the in vitro expansion of HSCs. The composite scaffold was prepared by forming a photo-cross-linked Gel-HA hydrogel surrounding the GF. The "soft" Gel-HA hydrogel and "stiff" GF replicate the structure and stiffness of the vascular niche and endosteal niche in the bone marrow, respectively. Furthermore, HSCs cultured in the Gel-HA/GF scaffold proliferated well and retained the CD34+CD38- immunophenotype and pluripotency, suggesting that the Gel-HA/GF composite scaffold supported the in vitro expansion of HSCs, maintaining the primitive phenotype and the ability to differentiate into functional blood cells. Thus, the hydrogel/graphene composite scaffold offers a means of facilitating HSC expansion through structurally and mechanically mimicking bone marrow niches, demonstrating great promise for HSC transplantation.

Adhesion States Greatly Affect Cellular Susceptibility to Graphene Oxide: Therapeutic Implications for Cancer Metastasis.

Graphene oxide (GO) has received increasing attention in the life sciences because of its potential for various applications. Although GO is generally considered biocompatible, it can negatively impact cell physiology under some circumstances. Here, we demonstrate that the cytotoxicity of GO greatly varies depending on the cell adhesion states. Human HCT-116 cells in a non-adhered state were more susceptible to GO than those in an adherent state. Apoptosis was partially induced by GO in both adhered and non-adhered cells to a similar extent, suggesting that apoptosis induction does not account for the selective effects of GO on non-adhered cells. GO treatment rapidly decreased intracellular ATP levels in non-adhered cells but not in adhered ones, suggesting ATP depletion as the primary cause of GO-induced cell death. Concurrently, autophagy induction, a cellular response for energy homeostasis, was more evident in non-adhered cells than in adhered cells. Collectively, our observations provide novel insights into GO's action with regard to cell adhesion states. Because the elimination of non-adhered cells is important in preventing cancer metastasis, the selective detrimental effects of GO on non-adhered cells suggest its therapeutic potential for use in cancer metastasis.

Engineering Atomic Ag1-N6 Sites with Enhanced Performance of Eradication Drug-Resistant Bacteria over Visible-Light-Driven Antibacterial Membrane.

Utilizing visible light for water disinfection is a more convenient, safe, and practical alternative to ultraviolet-light sterilization. Herein, we developed silver (Ag) single-atom anchored g-C3N4 (P-CN) nanosheets (Ag1/CN) and then utilized a spin-coating method to fabricate the Ag1/CN-based-membrane for effective antibacterial performance in natural water and domestic wastewater. The incorporated Ag single atom formed a Ag1-N6 motif, which increased the charge density around the N atoms, resulting in a built-in electric field ∼17.2 times stronger than that of pure P-CN and optimizing the dynamics of reactive oxygen species (ROS) production. Additionally, the Ag1-N6 motif inhibited the release of Ag ions, ensuring good biocompatibility. Based on the first-principles calculation, the adsorption energy of O2 on the Ag1/CN (-0.32 eV) was lower than that of P-CN (-0.07 eV), indicating that loaded Ag single atom can lower the energy barrier for O2 activation, generating extra *OH radicals that cooperated with *O2- to effectively neutralize bacteria. As a result, the Ag1/CN powder-catalyst with the concentration of 30 ppm demonstrated a 99.9% antibacterial efficiency against drug-resistant bacteria (Escherichia coli, Staphylococcus aureus, kanamycin-resistant Escherichia coli, and methicillin-resistant Staphylococcus aureus) under visible-light irradiation for 4 h. This efficacy was 24.8 times higher than that of the P-CN powder catalyst. Moreover, the Ag1/CN-based-membrane can maintain a 99.9% bactericidal efficiency for natural water and domestic wastewater treatment using a homemade flow device, demonstrating its potential for water disinfection. Notably, the visible-light-driven antibacterial efficiency of the Ag1/CN catalyst outperformed the majority of the reported g-C3N4-based catalysts/membranes.

New graphene-containing pharmaceutical formulations for infrared lamps-based phototherapy of skin cancer: In vitro validation and ex-vivo human skin permeation.

Basal cell carcinoma (BCC) is the most common form of human cancer, and treatment usually involves surgery, with alternative strategies being needed. We propose the use of carbopol hydrogels (HG) for topical administration of nanographene oxide (GOn) and partially-reduced nanographene oxide (p-rGOn) for photothermal therapy (PTT) of BCC. GOn and p-rGOn incorporated into the HG present lateral sizes ∼200 nm, being stable for 8 months. After 20 min irradiation with an infrared (IR) photothermal therapy lamp (15.70 mW cm-2), GOn-HG increased temperature to 44.7 °C, while p-rGOn-HG reached 47.0 °C. Human skin fibroblasts (HFF-1) cultured with both hydrogels (250 µg mL-1) maintained their morphology and viability. After 20 min IR irradiation, p-rGOn HG (250 µg mL-1) completely eradicated skin cancer cells (A-431). Ex vivo human skin permeability tests showed that the materials can successfully achieve therapeutic concentrations (250 µg mL-1) inside the skin, in 2.0 h for GO HG or 0.5 h for p-rGOn HG.

Reduced graphene oxide-reinforced tricalcium phosphate/gelatin/chitosan light-responsive scaffolds for application in bone regeneration.

Bone is a mineralized tissue with the intrinsic capacity for constant remodeling. Rapid prototyping techniques, using biomaterials that mimic the bone native matrix, have been used to develop osteoinductive and osteogenic personalized 3D structures, which can be further combined with drug delivery and phototherapy. Herein, a Fab@Home 3D Plotter printer was used to promote the layer-by-layer deposition of a composite mixture of gelatin, chitosan, tricalcium phosphate, and reduced graphene oxide (rGO). The phototherapeutic potential of the new NIR-responsive 3D_rGO scaffolds was assessed by comparing scaffolds with different rGO concentrations (1, 2, and 4 mg/mL). The data obtained show that the rGO incorporation confers to the scaffolds the capacity to interact with NIR light and induce a hyperthermy effect, with a maximum temperature increase of 16.7 °C after under NIR irradiation (10 min). Also, the increase in the rGO content improved the hydrophilicity and mechanical resistance of the scaffolds, particularly in the 3D_rGO4. Furthermore, the rGO could confer an NIR-triggered antibacterial effect to the 3D scaffolds, without compromising the osteoblasts' proliferation and viability. In general, the obtained data support the development of 3D_rGO for being applied as temporary scaffolds supporting the new bone tissue formation and avoiding the establishment of bacterial infections.

Preparation of PDA-GO/CS composite scaffold and its effects on the biological properties of human dental pulp stem cells.

Reduced graphene oxide (rGO) is an graphene oxide (GO) derivative of graphene, which has a large specific surface area and exhibited satisfactory physicochemical characteristics. In this experiment, GO was reduced by PDA to generate PDA-GO complex, and then PDA-GO was combined with Chitosan (CS) to synthesize PDA-GO/CS composite scaffold. PDA-GO was added to CS to improve the degradation rate of CS, and it was hoped that PDA-GO/CS composite scaffolds could be used in bone tissue engineering. Physicochemical and antimicrobial properties of the different composite scaffolds were examined to find the optimal mass fraction. Besides, we examined the scaffold's biocompatibility by Phalloidin staining and Live and Dead fluorescent staining.Finally, we applied ALP staining, RT-qPCR, and Alizarin red S staining to detect the effect of PDA-GO/CS on the osteogenic differentiation of human dental pulp stem cells (hDPSCs). The results showed that PDA-GO composite was successfully prepared and PDA-GO/CS composite scaffold was synthesized by combining PDA-GO with CS. Among them, 0.3%PDA-GO/CS scaffolds improves the antibacterial activity and hydrophilicity of CS, while reducing the degradation rate. In vitro, PDA-GO/CS has superior biocompatibility and enhances the early proliferation, migration and osteogenic differentiation of hDPSCs. In conclusion, PDA-GO/CS is a new scaffold materialsuitable for cell culture and has promising application prospect as scaffold for bone tissue engineering.

The Influence of Graphene Oxide-Fe3O4 Differently Conjugated with 10-Hydroxycampthotecin and a Rotating Magnetic Field on Adenocarcinoma Cells.

Nanoparticles (e.g., graphene oxide, graphene oxide-Fe3O4 nanocomposite or hexagonal boron nitride) loaded with anti-cancer drugs and targeted at cancerous cells allowed researchers to determine the most effective in vitro conditions for anticancer treatment. For this reason, the main propose of the present study was to determine the effect of graphene oxide (GO) with iron oxide (Fe3O4) nanoparticles (GO-Fe3O4) covalently (c-GO-Fe3O4-HCPT) and non-covalently (nc-GO-Fe3O4-HCPT) conjugated with hydroxycamptothecin (HCPT) in the presence of a rotating magnetic field (RMF) on relative cell viability using the MCF-7 breast cancer cell line. The obtained GO-Fe3O4 nanocomposites demonstrated the uniform coverage of the graphene flakes with the nanospheres, with the thickness of the flakes estimated as ca. 1.2 nm. The XRD pattern of GO-Fe3O4 indicates that the crystal structure of the magnetite remained stable during the functionalization with HCPT that was confirmed with FTIR spectra. After 24 h, approx. 49% and 34% of the anti-cancer drug was released from nc-GO-Fe3O4-HCPT and c-GO-Fe3O4-HCPT, respectively. The stronger bonds in the c-GO-Fe3O4-HCPT resulted in a slower release of a smaller drug amount from the nanocomposite. The combined impact of the novel nanocomposites and a rotating magnetic field on MCF-7 cells was revealed and the efficiency of this novel approach has been confirmed. However, MCF-7 cells were more significantly affected by nc-GO-Fe3O4-HCPT. In the present study, it was found that the concentration of nc-GO-Fe3O4-HCPT and a RMF has the highest statistically significant influence on MCF-7 cell viability. The obtained novel nanocomposites and rotating magnetic field were found to affect the MCF-7 cells in a dose-dependent manner. The presented results may have potential clinical applications, but still, more in-depth analyses need to be performed.

Few-layered graphene increases the response of nociceptive neurons to irritant stimuli.

The unique properties of few-layered graphene (FLG) make it interesting for a variety of applications, including biomedical applications, such as tissue engineering and drug delivery. Although different studies focus on applications in the central nervous system, its interaction with the peripheral nervous system has been so far overlooked. Here, we investigated the effects of exposure to colloidal dispersions of FLG on the sensory neurons of the rat dorsal root ganglia (DRG). We found that the FLG flakes were actively internalized by sensory neurons, accumulated in large intracellular vesicles, and possibly degraded over time, without major toxicological concerns, as neuronal viability, morphology, protein content, and basic electrical properties of DRG neurons were preserved. Interestingly, in our electrophysiological investigation under noxious stimuli, we observed an increased functional response upon FLG treatment of the nociceptive subpopulation of DRG neurons in response to irritants specific for chemoreceptors TRPV1 and TRPA1. The observed effects of FLG on DRG neurons may open-up novel opportunities for applications of these materials in specific disease models.

Evaluation of the Antibacterial, Anti-Cervical Cancer Capacity, and Biocompatibility of Different Graphene Oxides.

Cancer stands as one of the deadliest diseases in human history, marked by an inferior prognosis. While traditional therapeutic methods like surgery, chemotherapy, and radiation have demonstrated success in inhibiting tumor cell growth, their side effects often limit overall benefits and patient acceptance. In this regard, three different graphene oxides (GO) with variations in their degrees of oxidation were studied chemically and tissue-wise. The accuracy of the synthesis of the different GO was verified by robust techniques using X-ray photoelectron spectroscopy (XPS), as well as conventional techniques such as infrared spectroscopy (FTIR), RAMAN spectroscopy, and X-ray diffraction (XRD). The presence of oxygenated groups was of great importance. It affected the physicochemical properties of each of the different graphene oxides demonstrated in the presence of new vibrational modes related to the formation of new bonds promoted by the graphitization of the materials. The toxicity analysis in the Hep-2 cell line of graphene oxide formulations at 250 µg/mL on the viability and proliferation of these tumor cells showed low activity. GO formulations did not show high antibacterial activity against Staphylococcus aureus and Escherichia coli strains. However, the different graphene oxides showed biocompatibility in the subdermal implantation model for 30, 60, and 90 days in the biomodels. This allowed healing by restoring hair and tissue architecture without triggering an aggressive immune response.

Blue-light-driven photoactivity of L-cysteine-modified graphene quantum dots and their antibacterial effects.

The widespread abuse of traditional antibiotics has led to a global rise in antibiotic-resistant bacteria, which give in return unprecedented health risks. Therefore, there is a large and urgent need for the development of new, smart antibacterial agents able to efficiently kill or inhibit bacterial growth. In this study, we investigated the antibacterial activity of S, N-doped Graphene Quantum Dots (GQDs) as a light-triggered antibacterial agent. Gamma irradiation was employed as a tool to achieve one-step modification of GQDs in the presence of L-cysteine amino acid as a source of heteroatoms. X-ray Photoelectron Spectroscopy (XPS), nuclear magnetic resonance (NMR), and zeta potential measurements provided the necessary data to clarify the structure of modified dots and verify the introduction of both S- and N-atoms in GQDs structure, but also severe changes in the aromatic, sp2 domains. Namely, γ-irradiation caused a bonding of S atoms in 1.14 at.% mainly as thiol groups, and N in 1.81 at.% as amino groups, but sp2 contribution in GQD structure was lowered from 63.00 to 4.86 at.%, as measured in dots irradiated at a dose of 200 kGy. Fluorescence quenching measurements showed that L-cysteine-modified dots are able to bind to human serum albumin. The antibacterial activity of GQDs combined with 1 and 6 h of blue light (470 nm) irradiation was tested against 8 bacterial strains. GQD-cys-25 sample provided the best results, with minimum inhibitory concentration (MIC) as low as 125 µg/mL against S. aureus, E. faecalis, and E. coli after only 1 h of blue light exposure.

Graphene quantum dots based on cannabis seeds for efficient wound healing in a mouse incisional wound model: Link with stress and neurobehavioral effect.

Graphene quantum dots (GQDs) are promising biomaterials with potential applicability in several areas due to their many useful and unique features. Among different applications, GQDs are photodynamic therapy agents that generate single oxygen and improve antimicrobial activity. In the present study, and for the first time, GQD were isolated from the Cannabis sativa L. seeds to generate C-GQDs as a new biomaterial for antibacterial and wound healing applications. Detailed characterization was performed using FTIR, UV-vis, Raman spectra, photoluminescence, TEM examination, HRTEM, ζ-potential, and XRD. Our results revealed in vitro and in vivo antibacterial activity of C-GQDs against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) with reduced minimal inhibitory concentration of 236 µg/mL for both strains. In addition, the C-GQDs confirmed the in vitro analysis and exhibited anti-inflammatory activity by reducing the level of neutrophils in blood and skin tissue. C-GQDs act by accelerating re-epithelization and granulation tissue formation. In addition, C-GQDs restored neurobehavioral alteration induced by incisional wounds by reducing oxidative stress, decreasing cortisol levels, increasing anxiolytic-like effect, and increasing vertical locomotor activity. The wound-healing effects of C-GQDs support its role as a potential therapeutic agent for diverse skin injuries.

Long-term in vivo degradation and biocompatibility of degradable pHEMA hydrogels containing graphene oxide.

Developing biocompatible, non-fouling and biodegradable hydrogels for blood-contacting devices remains a demanding challenge. Such materials should promote natural healing, prevent clotting, and undergo controlled degradation. This study evaluates the biocompatibility and biodegradation of degradable poly(2-hydroxyethyl methacrylate) (d-pHEMA) hydrogels with or without reinforcement with oxidized few-layer graphene (d-pHEMA/M5ox) in a long term implantation in rats, assessing non-desired side-effects (irritation, chronic toxicity, immune response). Subcutaneous implantation over 6 months revealed degradation of both hydrogels, despite slower for d-pHEMA/M5ox, with degradation products found in intracellular vesicles. No inflammation nor infection at implantation areas were observed, and no histopathological findings were detected in parenchymal organs. Immunohistochemistry confirmed d-pHEMA and d-pHEMA/M5ox highly anti-adhesiveness. Gene expression of macrophages markers revealed presence of both M1 and M2 macrophages at all timepoints. M1/M2 profile after 6 months reveals an anti-inflammatory environment, suggesting no chronic inflammation, as also demonstrated by cytokines (IL-α, TNF-α and IL-10) analysis. Overall, modification of pHEMA towards a degradable material was successfully achieved without evoking a loss of its inherent properties, specially its anti-adhesiveness and biocompatibility. Therefore, these hydrogels hold potential as blank-slate for further modifications that promote cellular adhesion/proliferation for tissue engineering applications, namely for designing blood contacting devices with different load bearing requirements. STATEMENT OF SIGNIFICANCE: Biocompatibility, tunable biodegradation kinetics, and suitable immune response with lack of chronic toxicity and irritation, are key features in degradable blood contact devices that demand long-term exposure. We herein evaluate the 6-month in vivo performance of a degradable and hemocompatible anti-adhesive hydrogel based in pHEMA, and its mechanically reinforced formulation with few-layer graphene oxide. This subcutaneous implantation in a rat model, shows gradual degradation with progressive changes in material morphology, and no evidence of local inflammation in surrounding tissue, neither signs of inflammation or adverse reactions in systemic organs, suggesting biocompatibility of degradation products. Such hydrogels exhibit great potential as a blank slate for tissue engineering applications, including for blood contact, where cues for specific cells can be incorporated.