Graphene Oxide-Silver Nanoparticle Nanohybrids: Synthesis, Characterization, and Antimicrobial Properties

Electrochemical detection of creatinine at picomolar scale with an extended linear dynamic range in human body fluids for diagnosis of kidney dysfunction

BACKGROUND

Creatinine levels in different body fluids can serve as an important biomarker for kidney functioning relevant to prostate cancer and chronic kidney disease (CKD). Creatinine levels vary in concentration in different body fluids, such as blood, urine, and saliva. Unlike previously reported sensors, the developed creatinine sensor can be employed for all levels of creatinine in samples of real patients.

RESULTS

In this study, an efficient voltammetric sensor for creatinine is developed by modifying a glassy carbon electrode (GCE) with poly (ethyleneimine) (PEI) capped silver nanoparticles at titanium dioxide (PEI-AgNPs)/TiO2, i.e., titanium dioxide (TiO2)/graphene oxide (GO) nanocomposites (Ag@GO/TiO2-GCE). The Ag@GO/TiO2 nanocomposite was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), thermal gravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential, Fourier transform infrared (FT-IR) spectroscopy, and UV-Vis spectrophotometry. Various voltammetric techniques namely cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), chronoamperometry (CA), and differential pulse voltammetry (DPV) were employed. The Ag@GO/TiO2-GCE demonstrated good selectivity, stability, and a quick response time of 1.0 s for creatinine. An extended linear dynamic range (LDR) of creatinine from 0.01 pM (DPV) to 1.0 M (CV) based on different voltammetric techniques is imperative for detecting diverse creatinine levels in various body fluids. The LOD and LOQ of the developed creatinine detection method were found to be 1.15 pM and 3.5 pM, respectively. The electrochemical sensor exhibited an exceptionally high sensitivity of 15.74 μApM-1cm-2.The body fluids from healthy volunteers were spiked with a known amount of creatinine to evaluate sensor efficiency in the context of recovery. Finally, blood serum, saliva, and urine samples of kidney patients were analyzed for creatinine levels.

SIGNIFICANCE

An important merit of the developed creatinine sensor is its ability for non-invasive point-of-care diagnosis in saliva with more than 90 % recovery. The comparison of the developed method with the standard Jaffes' colorimetric method endorsed its reliability and extended ability for the samples where Jaffes' method fails. The low LOD, high sensitivity, extended LDR, and low-cost render the possibility of adopting this method for point-of-care diagnosis.

Enhancing organoid technology with carbon-based nanomaterial biosensors: Advancements, challenges, and future directions

Various carbon-based nanomaterials (CBNs) have been utilized to develop nano- and microscale biosensors that enable real-time and continuous monitoring of biochemical and biophysical changes in living biological systems. The integration of CBN-based biosensors into organoids has recently provided valuable insights into organoid development, disease modeling, and drug responses, enhancing their functionality and expanding their applications in diverse biomedical fields. These biosensors have been particularly transformative in studying neurological disorders, cardiovascular diseases, cancer progression, and liver toxicity, where precise, non-invasive monitoring is crucial for understanding pathophysiological mechanisms and assessing therapeutic efficacy. This review introduces intra- and extracellular biosensors incorporating CBNs such as graphene, carbon nanotubes (CNTs), graphene oxide (GO), reduced graphene oxide (rGO), carbon dots (CDs), and fullerenes. Additionally, it discusses strategies for improving the biocompatibility of CBN-based biosensors and minimizing their potential toxicity to ensure long-term organoid viability. Key challenges such as biosensor integration, data accuracy, and functional compatibility with specific organoid models are also addressed. Furthermore, this review highlights how CBN-based biosensors enhance the precision and relevance of organoid models in biomedical research, particularly in organ-specific applications such as brain-on-a-chip systems for neurodegenerative disease studies, liver-on-a-chip platforms for hepatotoxicity screening, and cardiac organoids for assessing cardiotoxicity in drug development. Finally, it explores how biosensing technologies could revolutionize personalized medicine by enabling high throughput drug screening, patient-specific disease modeling, and integrated sensing platforms for early diagnostics. By capturing current advancements and future directions, this review underscores the transformative potential of carbon-based nanotechnology in organoid research and its broader impact on medical science.

Concentration-dependent disturbances of digestive functions in house cricket (Insecta: Orthoptera) exposed to GO-AgNP composite

This study investigates the effects of graphene oxide (GO) and silver nanoparticle (AgNP) composite (GO-AgNP) on the digestive physiology and gut ultrastructure of Acheta domesticus (house cricket) during extended exposure. Various concentrations of GO-AgNP were tested to assess their impact on food consumption, assimilation, cell status (Dead Cells and ROS + cells), gut enzyme activity, and structural damage to gut cells. Concentration and exposure time had significant effects on oxidative stress, enzyme activity, and gut cell structure. The applied composite reduced cumulative food consumption and assimilation efficiency. Enzyme assays showed that lower concentrations enhanced carbohydrate-degrading enzyme activity, while higher concentrations inhibited protease activity. Histological analysis revealed structural damage to gut epithelial cells and signs of autophagy or necrosis at higher concentrations. These results suggest that GO and AgNPs contribute to oxidative stress, cell cycle disruption, and apoptosis, with AgNPs having a potentially stronger effect than GO. The disturbed enzyme activity may result from conformational changes caused by nanoparticle agglomeration. These findings underline potential risks associated with the environmental or agricultural use of GO-AgNP composites.

Unlocking the power of nanohybrids: A critical review on carbon nanomaterial-functionalized silver nanoparticles for advanced antimicrobial applications

Over the last decades, nanotechnology has enabled the development of several inorganic nanoparticles with significant biocidal properties against diverse microorganisms. Silver nanoparticles (AgNPs) are among the most promising antimicrobial nanomaterials that have attracted substantial attention in various fields due to their low cost, low toxicity, biocompatibility, photo and chemical stability, easy preparation, high fluorescence, and tunability. Carbon nanomaterials (CNMs) are another appealing nanomaterial with antimicrobial qualities. While the antimicrobial efficacy of both AgNPs and CNMs is well-established, there is significant interest in the creation of CNMs/AgNPs hybrid materials for several applications due to their potential to exhibit synergistic bactericidal properties that surpass the yields of their components. This review represents a general overview of the different kinds, characterization techniques, synthesis processes, and antimicrobial activity of CNMs/AgNPs, along with an analysis of their benefits, drawbacks, and antimicrobial applications. Researchers and scientists interested in learning more about the potential of CNMs/AgNPs for advanced antimicrobial applications are likely to find this review to be a valuable resource.

Recent advances of silver nanoparticle-based polymer nanocomposites for biomedical applications

Silver nanoparticle-polymer nanocomposites (AgNP-PNCs) represent a transformative advancement in biomedical material science, integrating the potent antimicrobial properties of AgNPs with the structural versatility of polymer matrices. This synergy enables enhanced infection control, mechanical stability, and controlled drug delivery, making these nanocomposites highly suitable for applications such as wound healing, medical coatings, tissue engineering, and biosensors. Recent progress in synthesis and functionalization has led to greater control over particle morphology, dispersion, and stability, optimizing AgNP-PNCs for clinical and translational applications. However, challenges related to cytotoxicity, long-term stability, immune response, and scalability persist, necessitating systematic improvements in surface functionalization, hybridization strategies, and biocompatibility assessments. This review critically evaluates the latest advancements in AgNP-PNC development, focusing on their functionalization techniques, regulatory considerations, and emerging strategies to overcome biomedical challenges. Additionally, it discusses preclinical and translational aspects, including commercialization barriers and regulatory frameworks such as FDA and EMA guidelines, ensuring a comprehensive outlook on their clinical feasibility. By bridging the gap between innovation and practical application, this review investigates the transformative potential of AgNP-PNCs in advancing next-generation biomedical materials.

Functionalization of collagen fiber with nano-islands of silver via atomic layer deposition to promote bone healing

Modern techniques of thin film deposition (e.g., atomic layer deposition [ALD]) have paved the way for the modification of the surface of target substrates with thin films, nanoparticles, or other types of nanomaterials. This novel way can improve the base material's properties and enhance specific properties through adding functionalized groups to the surface. In this study, ALD of silver was conducted on commercially available Type I collagen membrane to improve its bioactivity and promote bone healing. Two different sample groups were studied: pristine collagen and silver-coated collagen via ALD (Ag/Collagen). Chemical and morphological changes of the collagen membrane were investigated with X-ray photoelectron spectroscopy and scanning electron microscopy and the bioactivity of functionalized collagen with silver was studied in vitro and in vivo. Nano-islands of silver were obtained on collagen fibrils with an average diameter of ∼16 nm. Comparison of gingival cells cultured on pristine collagen, and silver-coated collagen, demonstrated that the attained silver nanoparticle size and concentration are below the toxicity level of silver. In vivo assessment in rat model showed the biocompatibility of the Ag/Collagen, and greater new bone formation compared to control. This novel solvent-free method can be used to functionalize sensitive materials used in surgeries as bone grafting agents to enhance osteopromotive properties without any adverse effects to the cellular environment.

A thermal perspective of the advancements in antibacterial polycaprolactone/graphene scaffolds

Excessive activation of osteoclasts during bone infections can result in destructive bone complications, including non-union and delayed fracture healing. Enterococcus faecalis and Streptococcus pyogenes are known pathogens associated with bone and joint infections, which can lead to severe complications and the deterioration of tissue. This study aimed to investigate the potential of mechano-bacteria intervention in combating these bacteria. Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) tests were conducted on Polycaprolactone (PCL) and PCL/graphene (G) scaffolds containing different concentrations of graphene, namely 0.5, 1.5, and 2.5 wt%, to evaluate the thermal impact on the activity of E. faecalis and S. pyogenes. Furthermore, the Kirby Bauer Method was used to assess the antibacterial activity against both bacteria. The analysis of the average inhibition zone showed a correlation between the antibacterial effect and the concentration of G within the scaffolds. The highest inhibition zone was observed when 2.5 wt% G was used for both E. faecalis and S. pyogenes. The higher Tmax from Thermogravimetric Analysis showed PCL/G with 2.5 wt% G was due to the greater heat energy required to break down sp2 hybridized carbon atoms in a hexagonal framework. The TGA results indicate that higher graphene content (2.5 wt%) requires more energy for thermal decomposition compared to lower concentrations (0.5 wt% and 1.5 wt%) and PCL while the DSC results also showed that presence of G had a significant impact on Tg (glass transition temperature), Tc (crystallization temperature), and Tm (melting temperature), as the temperature increased with the addition of G. Based on the result of this study, it was concluded that G had potential for inhibiting bacteria growth.

Preparation methods, applications, toxicity and mechanisms of silver nanoparticles as bactericidal agent and superiority of green synthesis method

Silver nanoparticles (SNPs) are a type of nanomaterial with wide applications in water treatment, medicine, food packaging, and industrial processes. Their unique optical, electrical, thermal conductivity, and biological properties distinguish them from other metal ions and liken them to noble metals like gold and copper. The present review explores the diverse applications, preparation techniques, mechanism of action of SNPs, and properties of SNPs focusing on their bactericidal activities and potential impacts on human health. Different preparation methods, encompassing chemical, physical, and biological techniques, were reviewed and analyzed to comprehend their effect on the properties and applications of SNPs. Studies revealed that the SNPs exhibit excellent antibactericidal properties. Mechanisms underlying their antimicrobial effects were explored, primarily focusing on pathogen-scavenging activities. Despite the promising benefits of SNPs, their potential toxicity to human health must be carefully managed. Regulatory standards, such as those set by WHO and USEPA; establish a maximum tolerable limit of 0.1 mg/L to mitigate health risks associated with SNP exposure. It is recommended to continue research into safer applications and alternative formulations of SNPs to minimize potential health risks while maximizing their beneficial applications across different industries.

Graphene-based metal/metal oxide nanocomposites as potential antibacterial agents: a mini-review

Antimicrobial resistance (AMR) is a rising issue worldwide, which is increasing prolonged illness and mortality rates in the population. Similarly, bacteria have generated multidrug resistance (MDR) by developing various mechanisms to cope with existing antibiotics and therefore, there is a need to develop new antibacterial and antimicrobial agents. Biocompatible nanomaterials like graphene and its derivatives, graphene oxide (GO), and reduced graphene oxide (rGO) loaded with metal/metal oxide nanoparticles have been explored as potential antibacterial agents. It is observed that nanocomposites of GO/rGO and metal/metal oxide nanoparticles can result in the synthesis of less toxic, more stable, controlled size, uniformly distributed, and cost-effective nanomaterials compared to pure metal nanoparticles. Antibacterial studies of these nanocomposites show their considerable potential as antibacterial and antimicrobial agents, however, issues like the mechanism of antimicrobial action and their cytotoxicity need to be explored in detail. This review highlights a comparative analysis of graphene-based metal and metal oxide nanoparticles as potential antibacterial agents against AMR and MDR.

A Facile and Green Approach for the Preparation of Silver Nanoparticles on Graphene Oxide with Favorable Antibacterial Activity

Herein, we introduce a simple precipitation method for preparing graphene oxide-silver nanoparticle (GO/AgNP) composites, utilizing Calendula officinalis (C. officinalis) seed extract as both a reducing and stabilizing agent. Our research combines the sustainable preparation of graphene oxide (GO) with the green synthesis of silver nanoparticles (AgNPs), aiming to explore the potential of the obtained composite as a novel antibacterial material. To establish a benchmark, the synthesis was also performed using sodium citrate, a conventional reducing agent. The resultant GO/AgNP composites were characterized through several analytical techniques, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy, X-ray diffraction (XRD), infrared (IR) spectroscopy, and ultraviolet-visible (UV-vis) spectroscopy, confirming the successful functionalization of GO with AgNPs. The antibacterial effectiveness of the composites was systematically assessed against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), with nanoparticle concentrations spanning from 0 to 250 µg/mL, utilizing mostly disk diffusion and colony-forming unit (CFU) count assays. The AgNPs were characterized by a size range of 15-50 nm. Notably, the GO/AgNP composite prepared using C. officinalis seed extract demonstrated superior antibacterial activity at all tested concentrations, outperforming both pure GO and the GO/AgNP composite prepared with sodium citrate. The most pronounced antibacterial effect was observed at a concentration of 32.0 µg/mL. Therefore, this innovative synthesis approach may offer a valuable contribution to the development of new therapeutic agents to combat bacterial infections, suggesting further exploration into antibacterial coatings or potential drug development.

Intrinsic physiochemical insights to green synthesized Ag-decorated GO nanosheet for photoluminescence and in vivo cellular biocompatibility with embryonic zebrafish

The advancement of nanotechnology and their application has intrigued a significant interest in green synthesis and application of organic and inorganic nanomaterials like graphene oxide (GO) and silver nanoparticles (AgNP). This study explores the intrinsic physiochemical properties of silver (Ag)-decorated graphene oxide (GO) nanosheets synthesized via a green approach, focusing on their photoluminescence behaviour and in vivo cellular biocompatibility with embryonic zebrafish. The nanocomposites were characterized using various spectroscopic and microscopic techniques to elucidate their structural and optical properties. Results reveal that the Ag-decorated GO nanosheets exhibit enhanced photoluminescence compared to pristine GO with an SPR at 405 nm and emission at 676 nm, attributed to the synergistic effects of Ag nanoparticles and GO. In addition, in vivo biocompatibility assessments using embryonic zebrafish demonstrate minimal cytotoxicity and high cellular viability upon exposure to the nanocomposites with an LC50 of 38 µg/ml, indicating their potential for biomedical applications. Further investigations into the interactions between the nanomaterials and biological systems provide valuable insights into their safety profile and suggest their suitability for various biomedical and therapeutic applications. Overall, this study offers a comprehensive understanding of the physiochemical characteristics and biological compatibility of Ag-decorated GO nanosheets, contributing to the advancement of nanotechnology in biomedicine and related fields.

Functionalized graphene oxide by 4-amino-3-hydroxy-1-naphthalenesulfonic acid as a heterogeneous nanocatalyst for the one-pot synthesis of tetraketone and tetrahydrobenzo[b]pyran derivatives under green conditions

4-Amino-3-hydroxy-1-naphthalenesulfonic acid-functionalized graphene oxide (GO-ANSA) was prepared and characterized using different spectroscopic, microscopic and analytical methods including energy-dispersive X-ray spectroscopy (EDS), EDS elemental mapping, Fourier-transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and thermogravimetry/differential thermogravimetry analysis (TGA/DTA). The obtained nanomaterial was used as a novel, highly efficient, and reusable solid acid carbocatalyst for the one-pot three-component synthesis of tetraketone, as well as tetrahydrobenzo[b]pyran derivatives via tandem Knoevenagel-Michael reactions under green conditions. All of the derivatives were prepared in EtOH, as a green solvent, under reflux conditions in high to excellent yields and very short reaction times. The nanocatalyst was recovered and reused at least five times without significant reduction in its activity. In addition, the absence of toxic transition metals, high to excellent yields, mild reaction conditions, simple procedure for the separation and purification of products, stability, and recycling of the catalyst are the most important advantages of this green procedure.

Advances in graphene-based 2D materials for tendon, nerve, bone/cartilage regeneration and biomedicine

Two-dimensional (2D) materials, especially graphene-based materials, have important implications for tissue regeneration and biomedicine due to their large surface area, transport properties, ease of functionalization, biocompatibility, and adsorption capacity. Despite remarkable progress in the field of tissue regeneration and biomedicine, there are still problems such as unclear long-term stability, lack of in vivo experimental data, and detection accuracy. This paper reviews recent applications of graphene-based materials in tissue regeneration and biomedicine and discusses current issues and prospects for the development of graphene-based materials with respect to promoting the regeneration of tendons, neuronal cells, bone, chondrocytes, blood vessels, and skin, as well as applications in sensing, detection, anti-microbial activity, and targeted drug delivery.

Determination of Photothermal and EMI Shielding Efficiency of Graphene-Silver Nanoparticle Composites Prepared under Low-Dose Gamma Irradiation

Silver nanoparticles (Ag NPs) have been produced by low-dose (1-20 kGy) gamma irradiation of silver nitrate in the presence of graphene-based material (graphene oxide or electrochemically exfoliated graphene). The large surface area of those graphene-based materials combined with the presence of oxygen-containing functional groups on the surface provided successful nucleation and growth of Ag nanoparticles, which resulted in a uniformly covered graphene surface. The obtained Ag nanoparticles were spherical with a predominant size distribution of 10-50 nm for graphene oxide and 10-100 nm for electrochemically exfoliated graphene. The photothermal efficiency measurement showed a temperature increase upon exposure to a 532 nm laser for all samples and the highest photothermal efficiency was measured for the graphene oxide/Ag NP sample prepared at 5 kGy. Electromagnetic interference (EMI) shielding efficiency measurements showed poor shielding for the composites prepared with graphene oxide. On the other hand, all composites prepared with electrochemically exfoliated graphene showed EMI shielding to some extent, and the best performance was measured for the samples prepared at 5 and 20 kGy doses.

Silver oxide decorated urchin-like microporous organic polymer composites as versatile antibacterial organic coating materials

Microporous organic polymers (MOPs) and metal oxide hybrid composites are considered valuable coating materials because of their versatility derived from the synergistic combination of MOPs' inherent dispersibility and the distinctive properties of metal oxides. In this study, we present the synthesis of sea-urchin-like MOPs hybridised with silver oxide nanoparticles (Ag2O NPs) to fabricate antibacterial composites suitable for potential antibacterial coating applications. Ag2O NP-decorated urchin-like MOPs (Ag2O@UMOPs) were synthesised by employing a combination of two methods: a one-pot Lewis acid-base interaction-mediated self-assembly and a straightforward impregnation process. The as-prepared Ag2O@UMOPs demonstrated high antibacterial efficacy against both E. coli (G-) and S. aureus (G+). The antibacterial mechanism of Ag2O@UMOPs mainly involved the synergistic effects of accumulation of Ag2O@UMOPs, the release of Ag+ ions, and the generation of reactive oxygen species. The exceptional processability and biosafety of Ag2O@UMOPs make them ideal organic coating materials for convenient application on various substrates. These remarkable features of Ag2O@UMOPs provide an effective platform for potential antibacterial applications in biological sciences.

Bioinspired silver nanoparticle-based nanocomposites for effective control of plant pathogens: A review

Plant pathogens, including bacteria, fungi, and viruses, pose significant challenges to the farming community due to their extensive diversity, the rapidly evolving phenomenon of multi-drug resistance (MDR), and the limited availability of effective control measures. Amid mounting global pressure, particularly from the World Health Organization, to limit the use of antibiotics in agriculture and livestock management, there is increasing consideration of engineered nanomaterials (ENMs) as promising alternatives for antimicrobial applications. Studies focusing on the application of ENMs in the fight against MDR pathogens are receiving increasing attention, driven by significant losses in agriculture and critical knowledge gaps in this crucial field. In this review, we explore the potential contributions of silver nanoparticles (AgNPs) and their nanocomposites in combating plant diseases, within the emerging interdisciplinary arena of nano-phytopathology. AgNPs and their nanocomposites are increasingly acknowledged as promising countermeasures against plant pathogens, owing to their unique physicochemical characteristics and inherent antimicrobial properties. This review explores recent advancements in engineered nanocomposites, highlights their diverse mechanisms for pathogen control, and draws attention to their potential in antibacterial, antifungal, and antiviral applications. In the discussion, we briefly address three crucial dimensions of combating plant pathogens: green synthesis approaches, toxicity-environmental concerns, and factors influencing antimicrobial efficacy. Finally, we outline recent advancements, existing challenges, and prospects in scholarly research to facilitate the integration of nanotechnology across interdisciplinary fields for more effective treatment and prevention of plant diseases.

A quadruplet 3-D laser scribed graphene/MoS2, functionalised N2-doped graphene quantum dots and lignin-based Ag-nanoparticles for biosensing

Troponin I is a protein released into the human blood circulation and a commonly used biomarker due to its sensitivity and specificity in diagnosing myocardial injury. When heart injury occurs, elevated troponin Troponin I levels are released into the bloodstream. The biomarker is a strong and reliable indicator of myocardial injury in a person, with immediate treatment required. For electrochemical sensing of Troponin I, a quadruplet 3D laser-scribed graphene/molybdenum disulphide functionalised N2-doped graphene quantum dots hybrid with lignin-based Ag-nanoparticles (3D LSG/MoS2/N-GQDs/L-Ag NPs) was fabricated using a hydrothermal process as an enhanced quadruplet substrate. Hybrid MoS2 nanoflower (H3 NF) and nanosphere (H3 NS) were formed independently by varying MoS2 precursors and were grown on 3D LSG uniformly without severe stacking and restacking issues, and characterized by morphological, physical, and structural analyses with the N-GQDs and Ag NPs evenly distributed on 3D LSG/MoS2 surface by covalent bonding. The selective capture of and specific interaction with Troponin I by the biotinylated aptamer probe on the bio-electrode, resulted in an increment in the charge transfer resistance. The limit of detection, based on impedance spectroscopy, is 100 aM for both H3 NF and H3 NS hybrids, with the H3 NF hybrid biosensor having better analytical performance in terms of linearity, selectivity, repeatability, and stability.

Crosslinked carboxymethyl cellulose colloidal solution for cotton thread coating in wound dressing: A rheological study

Cotton thread therapeutic properties as a wound dressing can be enhanced by utilising carboxymethyl cellulose-nanoparticles (CMC/NPs) colloidal solution as a coating solution. Nanoparticles such as graphene oxide (GO), graphene quantum dots (GQD), and silver nanoparticles (AgNP) stability in CMC was investigated through the rheological analysis and UV-Vis spectroscopy of the colloidal solutions. Citric acid (CA) acted as a crosslinker and was utilised to crosslink the colloidal solution with cotton thread. These CMC/NPs coated threads were subjected to mechanical properties and antibacterial activity analysis. Results obtained indicate less nanoparticle agglomeration and were stable in the CMC-based nanofluid. CMC/NPs rheological study suggested that colloidal solutions exhibited shear thinning behaviour and behaved as non-Newtonian fluids with n < 1. Crosslinked CMC/NPs appeared in a gel-like state as the viscoelasticity of the solution increased. Among the colloidal solutions, CMC/AgNP showed the highest enhancement with a significant difference at p < 0.05 in terms of mechanical and antibacterial properties. Consequently, the rheological properties and stability of CMC/NPs might influence the coating solution's appearance and refine the cotton thread's microstructure for a functional wound dressing to be further utilised as a coating solution for antibacterial cotton thread wound dressing material.

Synthesis of copper-reduced graphene oxide nanomaterials using glucose and study of its antibacterial and anticancer activities

In this work, glucose-capped copper nanoparticles decorated reduced graphene oxide nanomaterial are synthesized at 100 °C and 200 °C via chemical reduction method and studied for their antibacterial and anticancer activities. Synthesized nanomaterials were characterized using x-ray diffraction, Fourier-transform infrared, transmission electron microscope, and RAMAN. It is observed in transmission electron microscopy and selected area electron diffraction studies that copper nanoparticles deposited onto reduced graphene oxide are smaller than nanoparticles generated in the absence of reduced graphene oxide. Also, the size of copper nanoparticles synthesized at 200 °C is smaller than at 100 °C. Results suggest that Cu/Glu/rGO synthesized at both temperatures showed significant antibacterial activity againstEscherichia coliandBacillus anthracis,similarly, showed significant cell death in cancer cell lines [Cal33 and HCT-116 p53 (+/+)]. Interestingly, the nanomaterials were seen to be more effective against the cancer cell lines harboring aggregating mutant p53. Tumors with aggregating mutants of p53 are difficult to treat hence, Cu/Glu/rGO can be promising therapeutic agents against these difficult cancers. However, the antibacterial and anticancer activity of Cu/Glu/rGO synthesized at 100 °C where Cu2O form is obtained was found to be more effective compared to Cu/Glu/rGO synthesized at 200 °C where Cu form is obtained. Though fine-tuning of the material may be required for its commercial applications.

A high-efficient antibacterial and biocompatible polyurethane film with Ag@rGO nanostructures prepared by microwave-assisted method: Physicochemical and dermal wound healing evaluation

Wound infections are a significant issue that can hinder the wound healing process. One way to address this problem is by enhancing the antibacterial activity of wound dressings. Accordingly, this work focuses on developing a castor-oil-based antibacterial polyurethane nanocomposite film impregnated with silver nanoparticles (AgNPs) decorated on the surface of reduced graphene oxide (rGO) nanostructures (Ag@rGO). To this aim, rGOs act as a platform to stabilize AgNPs and improve their bioavailability and dispersion quality within the PU film. The microwave-assisted synthesis of Ag@rGO nanohybrids was proved by FTIR, XRD, TGA, FE-SEM, EDS, and TEM analyses. Compared to PU/GO, the effect of Ag@rGO nanohybrids on thermo-mechanical features, morphology, antibacterial activity, cytocompatibility, and in vivo wound healing was assessed. SEM photomicrographs revealed the enhanced dispersion of Ag@rGO nanohybrids compared to GO nanosheets. Besides, according to XRD results, PU/Ag@rGO nanocomposite film demonstrated higher microphase mixing, which could be due to the finely dispersed Ag@rGO nanostructures interrupting the hydrogen bonding interactions in the hard segments. Moreover, PU/Ag@rGO nanocomposite showed excellent antibacterial behavior with completely killing E. coli and S. aureus bacteria. In vitro and in vivo wound healing studies displayed PU/Ag@rGO film effectively stimulated fibroblast cells proliferation, migration and re-epithelialization. However, the prepared antibacterial PU/Ag@rGO nanocomposite film has the potential to be used as a biomaterial for dermal wound healing applications.

Effect of Graphene Oxide and Silver Nanoparticle Hybrid Composite on Acinetobacter baumannii Strains, Regarding Antibiotic Resistance and Prevalence of AMP-C Production

Background and Objectives: Growing antibiotic resistance among bacteria is a global issue that is becoming harder and more expensive to solve. Traditional treatment options are becoming less effective, causing more fatal outcomes of nosocomial infections. Since the development of new antibiotics has stagnated in the last decade, a novel approach is needed. Materials and Methods: Graphene-based materials are being developed and tested for various applications, and the medical field is no exception. We tested 98 clinical A. baumannii strains for antibiotic resistance, AMP-C production and the effectiveness of a graphene oxide and silver nanoparticle hybrid nanocomposite. The disc diffusion method was used to determine antibiotic susceptibility results. Antibiotic discs containing cefotaxime, cloxacillin and clavulanate were used to detect AMP-C production. The effectiveness of the GO-Ag hybrid nanocomposite was determined by counting colony forming units (CFUs) after a suspension of A. baumannii and the GO-Ag hybrid nanocomposite was plated on MH agar and incubated overnight to grow colonies. Results: In our research, we found that A. baumannii strains are resistant to the majority of commonly used antibiotics. Antibiotic resistance levels and AMP-C production can be factors, indicating the better effectiveness of the graphene oxide and silver nanoparticle hybrid nanocomposite. Conclusions: In this study, a GO-Ag hybrid nanocomposite was shown to have the potential to fight even the most problematic bacteria like A. baumannii.

A composite hydrogel with antibacterial and promoted cell proliferation dual properties for healing of infected wounds

Wound infection remains a major challenge for health professionals, because it delays wound healing and increases the overall cost and morbidity. Therefore, the development of new biomaterials with new antibacterial properties and healing effects remains a dire clinical need. To solve this problem, we developed silver nanoparticles embedded in γ-cyclodextrin metal-organic frameworks (Ag@MOF) and platelet-rich plasma (PRP)-loaded hydrogel systems based on methacrylated silk fibroin (SFMA) and methacrylate hyaluronic acid (HAMA) as Ag+ ion and growth factor delivery vehicles for inhibiting the growth of drug-resistant bacteria and promoting wound healing. The prepared SFMA/HAMA hydrogel demonstrated good rheological properties, swelling capability, appropriate mechanical properties and controllable biodegradability. The SFMA/HAMA/Ag@MOF/PRP hydrogel showed sustained release profiles of Ag+ ions and EGF. The SFMA/HAMA/Ag@MOF hydrogel have good inherent antibacterial properties against both gram-negative bacteria and gram-positive bacteria. The prepared hydrogel showed excellent cytocompatibility and could stimulate the growth and proliferation rate of NIH-3T3 cells. In vivo experiments showed that SFMA/HAMA/Ag@MOF/PRP hydrogel treatment enhanced the healing of full-thickness wounds, reduced inflammatory cell infiltration, and promoted re-epithelialization and collagen synthesis. All results indicated that the prepared hydrogel has tremendous potential to reduce wound infections and improve wound healing.

An ultrasensitive "mix-and-detect" kind of fluorescent biosensor for malaoxon detection using the AChE-ATCh-Ag-GO system

Malaoxon, a highly toxic metabolite of malathion, can lead to severe harm or death if ingested. This study introduces a rapid and innovative fluorescent biosensor that relies on acetylcholinesterase (AChE) inhibition for detecting malaoxon using Ag-GO nanohybrid. The synthesized nanomaterials (GO, Ag-GO) were evaluated with multiple characterization methods to confirm their elemental composition, morphology, and crystalline structure. The fabricated biosensor works by utilizing AChE to catalyze the substrate acetylthiocholine (ATCh), which generates positively charged thiocholine (TCh) and triggers citrate-coated AgNP aggregation on the GO sheet, leading to an increase in fluorescence emission at 423 nm. However, the presence of malaoxon inhibits the AChE action and reduces the production of TCh, resulting in a decrease in fluorescence emission intensity. This mechanism allows the biosensor to detect a wide range of malaoxon concentrations with excellent linearity and low LOD and LOQ values of 0.001 pM to 1000 pM, 0.9 fM, and 3 fM, respectively. The biosensor also demonstrated superior inhibitory efficacy towards malaoxon compared to other OP pesticides, indicating its resistance to external influences. In practical sample testing, the biosensor displayed recoveries of over 98% with extremely low RSD% values. Based on the results obtained from the study, it can be concluded that the developed biosensor has the potential to be used in various real-world applications for detecting malaoxon in food, and water samples, with high sensitivity, accuracy, and reliability.

The antimicrobial efficacy of nanographene oxide and double antibiotic paste per se and in combination: part II

BACKGROUND

Finding strategies to overcome the rising trends of antimicrobial resistance against currently available antimicrobial agents has become increasingly relevant. Graphene oxide has recently emerged as a promising material due to its outstanding physicochemical and biological properties. This study aimed to validate previous data on the antibacterial activity of nanographene oxide (nGO), double antibiotic paste (DAP), and their combination (nGO-DAP).

METHODS

The antibacterial evaluation was performed against a wide range of microbial pathogens. Synthesis of nGO was achieved using a modified Hummers' method, and loading it with ciprofloxacin and metronidazole resulted in nGO-DAP. The microdilution method was utilized to assess the antimicrobial efficacy of nGO, DAP, and nGO-DAP against two gram-positive bacteria (S. aureus and E. faecalis), two gram-negative bacteria (E. coli, and S. typhi), and an opportunistic pathogenic yeast (C. albicans). Statistical analysis was conducted using one-sample t-test and one-way ANOVA (α = 0.05).

RESULTS

All three antimicrobial agents significantly increased the killing percent of microbial pathogens compared to the control group (P < 0.05). Furthermore, the synthesized nGO-DAP exhibited higher antimicrobial activity than nGO and DAP per se.

CONCLUSION

The novel synthesized nGO-DAP can be used as an effective antimicrobial nanomaterial for use in dental, biomedical, and pharmaceutical fields against a range of microbial pathogens, including gram-negative and gram-positive bacteria, as well as yeasts.

A review on antimicrobial mechanism and applications of graphene-based materials

In recent years, graphene and its derivatives, owing to their phenomenal surface, and mechanical, electrical, and chemical properties, have emerged as advantageous materials, especially in terms of their potential for antimicrobial applications. Particularly important among graphene's derivatives is graphene oxide (GO) due to the ease with which its surface can be modified, as well as the oxidative and membrane stress that it exerts on microbes. This review encapsulates all aspects regarding the functionalization of graphene-based materials (GBMs) into composites that are highly potent against bacterial, viral, and fungal activities. Governing factors, such as lateral size (LS), number of graphene layers, solvent and GBMs' concentration, microbial shape and size, aggregation ability of GBMs, and especially the mechanisms of interaction between composites and microbes are discussed in detail. The current and potential applications of these antimicrobial materials, especially in dentistry, osseointegration, and food packaging, have been described. This knowledge can further drive research that aims to look for the most suitable components for antimicrobial composites. The need for antimicrobial materials has seldom been more felt than during the COVID-19 pandemic, which has also been highlighted here. Possible future research areas include the exploration of GBMs' ability against algae.

Graphene in nanomedicine: A review on nano-bio factors and antibacterial activity

Graphene-based nanomaterials possess potent antibacterial activity and have engrossed immense interest among researchers as an active armour against pathogenic microbes. A comprehensive perception of the antibacterial activity of these nanomaterials is critical to the fabrication of highly effective antimicrobial nanomaterials, which results in highly efficient and enhanced activity. These materials owing to their antimicrobial activity are utilized as nanomedicine against various pathogenic microbes. The present article reviews the antimicrobial activity of graphene and its analogs such as graphene oxide, reduced graphene oxide as well as metal, metal oxide and polymeric composites. The review draws emphasis on the effect of various nano-bio factors on the antibacterial capability. It also provides an insight into the antibacterial properties of these materials along with a brief discussion on the discrepancies in their activities as evidenced by the scientific communities. In this way, the review is expected to shed light on future research and development in graphene-based nanomedicine.

Fabrication of silver nanoparticles within chitosan based microgels for catalysis

Chitosan based monodisperse poly[chitosan-N-isopropylmethacrylamide-acrylic acid] [P(CNA)] microgels were produced via precipitation polymerization. Resulting crosslinked P(CNA) micro particles were used as micro-reactors to prepare silver nanoparticles within the polymeric network by chemical reduction of Ag⁺ ions with sodium borohydride. Various techniques including transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and ultraviolet-visible (UV-vis) spectroscopy were used to analyze P(CNA) microgels and Ag-P(CNA) hybrid microgels. Catalytic potential of Ag-P(CNA) hybrid system towards individual and simultaneous reduction of various nitroarenes like p-nitrophenol (pNP), o-nitrophenol (oNP), p-nitroaniline (pNA) and o-nitroaniline (oNA) into corresponding aminoarenes using sodium borohydride as a reductant in aqueous medium was evaluated. The catalytic activity of Ag-P(CNA) system towards both the individual and simultaneous reduction of nitroarenes was examined at various concentrations of catalyst. The values of pseudo first order rate constant (k₁) for reduction of individual nitroarene and multiple nitroarenes were determined for comparison. The Ag-P(CNA) hybrid microgel system was found to be stable, economical and efficient catalyst for rapid individual and simultaneous reduction of nitroarenes.

Macro-Size Regenerated Cellulose Fibre Embedded with Graphene Oxide with Antibacterial Properties

Macro-size regenerated cellulose fibres (RCFs) with embedded graphene oxide (GO) were fabricated by dissolving cellulose in a pre-cooled sodium hydroxide (NaOH)/urea solution and regenerated in sulphuric acid (H₂SO₄) coagulant. Initially, GO was found to disperse well in the cellulose solution due to intercalation with the cellulose; however, this cellulose-GO intercalation was disturbed during the regeneration process, causing agglomeration of GO in the RCF mixture. Agglomerated GO was confirmed at a higher GO content under a Dino-Lite microscope. The crystallinity index (CrI) and thermal properties of the RCFs increased with increasing GO loadings, up to 2 wt.%, and reduced thereafter. Cellulose-GO intercalation was observed at lower GO concentrations, which enhanced the crystallinity and thermal properties of the RCF-GO composite. It was shown that the GO exhibited antibacterial properties in the RCF-GO composite, with the highest bacterial inhibition against E. coli and S. aureus.

Graphene-Based Nanocomposites as Antibacterial, Antiviral and Antifungal Agents

Over the past decade, there have been many interesting studies in the scientific literature about the interaction of graphene-based polymeric nanocomposites with microorganisms to tackle antimicrobial resistance. These studies have reported variable intensities of biocompatibility and selectivity for the nanocomposites toward a specific strain, but it is widely believed that graphene nanocomposites have antibacterial, antiviral, and antifungal activities. Such antibacterial activity is due to several mechanisms by which graphene nanocomposites can act on cells including stimulating oxidative stress; disrupting membranes due to sharp edges; greatly changing core structure mechanical strength and coarseness. However, the underlying mechanisms of graphene nanocomposites as antiviral and antifungal agents remain relatively scarce. In this review, recent advances in the synthesis, functional tailoring, and antibacterial, antiviral, and antifungal applications of graphene nanocomposites are summarized. The synthesis of graphene materials and graphene-based polymeric nanocomposites with techniques such as pressurized gyration, electrospinning, chemical vapor deposition, and layer-by-layer self-assembly is first introduced. Then, the antimicrobial mechanisms of graphene membranes are presented and demonstrated typical in vitro and in vivo studies on the use of graphene nanocomposites for antibacterial, antiviral, and antifungal applications. Finally, the review describes the biosafety, current limitations, and potential of antimicrobial graphene-based nanocomposites.

Photochemical Optimization of a Silver Nanoprism/Graphene Oxide Nanocomposite's Antibacterial Properties

Optimizing the antibacterial properties of nanocomposites is a fundamental challenge for many biomedical applications. Here, we study how we may optimize the antibacterial activity of narrow-sized anisotropically flat silver nanoprisms (S-NPs) on graphene oxide (GO) against Escherichia coli. To do so, we transformed silver nanoparticles (AgNPs) into S-NPs and anchored them to GO via a facile and low-cost photochemical reduction method by varying the irradiation wavelength during the synthesis process in the visible range (440 to 650 nm and white light). We performed a physicochemical characterization of the resulting S-NP/GO nanocomposite using a combination of UV-vis spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Our results reveal a synergistic effect between the silver nanoprism and the oxygen functional groups of the GO surface. The antibacterial activity of the S-NPs/GO nanocomposite shows a significantly higher 53% inhibition efficiency after being irradiated with a 540 nm wavelength light source, compared to AgNPs with a 1% inhibition efficiency, respectively. In so doing, we have demonstrated the utility of a low-cost photoreduction method to control the structural properties of silver nanoprism on GO and, in this way, enhance the antibacterial properties of the nanocomposite. These results should be of great interest in a wide range of biomedical applications and medical devices.

Preparation, Characterization, and Evaluation of Curcumin-Graphene Oxide Complex-Loaded Liposomes against Staphylococcus aureus in Topical Disease

This study describes the development and characterization of curcumin with graphene oxide complex (CUR + GO) loaded into liposomes for treating skin disease. The developed complex was characterized by X-ray diffraction and showed a broad halo pattern, confirming the amorphous nature of the resulting complex. Furthermore, scanning electron microscopy revealed the irregular porous morphology of the complex-highlighting loss of the crystallinity and the emergence of the amorphous phase. Additionally, the liposomes showed long-term stability at 2-8 °C and 25 ± 2 °C/60 ± 5%RH with nonsignificant variations in the particle size, polydispersity index, and zeta potential. Overall, optical and high-resolution transmission electron microscopy images of liposomes showed a consistent shape, and no aggregation with uniform particle size distribution was observed. Furthermore, the cumulative drug release in the first 6 h was 71.24 and 64.24% for CUR-loaded liposomes and CUR-GO-loaded liposomes, respectively. The lower value of drug release might be attributed to the complex development. The drug release model found the first order with non-Fickian diffusion process, which is often observed at higher n > 0.5. The antibacterial activity of the CUR with GO-loaded liposome (D2) offered higher anti-microbial activity over other formulations against the mentioned bacterial microorganism that causes skin diseases.

Stability, Toxicity, and Antibacterial Potential of Gallic Acid-Loaded Graphene Oxide (GAGO) Against Methicillin-Resistant Staphylococcus aureus (MRSA) Strains

Background

The impetuous usage of antibiotics has led to the perpetual rise of methicillin-resistant Staphylococcus aureus (MRSA), which has garnered the interest of potential drug alternatives, including nanomaterials.

Purpose

The present study investigates the stability, toxicity, and antibacterial potential of gallic acid-loaded graphene oxide (GAGO) on several MRSA strains.

Methods

The stability of a synthesized and characterized GAGO was monitored in different physiological media. The toxicity profile of GAGO was evaluated in 3T3 murine fibroblast cells and the embryonic zebrafish model. The antibacterial activity of GAGO against MRSA, methicillin-susceptible S. aureus (MSSA), and community-acquired MRSA; with or without Panton-valentine leucocidin gene (MRSA-pvl+ and MRSA-pvl-) was investigated through disk diffusion, CFU counting method, time-kill experiment, and high-resolution transmission electron microscopy (HRTEM) observation.

Results

A stable GAGO nanocomposite has shown an improved toxicity profile in 3T3 murine fibroblast cells and zebrafish embryos, besides exhibiting normal ROS levels than graphene oxide (GO) and GA (gallic acid). The nanocomposite inhibited the growth of all bacterial strains employed. The effectiveness of the GAGO nanocomposite was comparable to cefoxitin (CFX), at ≥150 µg/mL in MRSA and MSSA. GAGO exhibited a significantly delayed response towards MRSA-pvl+ and MRSA-pvl-, with increased inhibition following 8 to 24 h of exposure, while comparable activity to native GA was only achieved at 24 h. Meanwhile, for MRSA and MSSA, GAGO had a comparable activity with native GA and GO as early as 2 h of exposure. HRTEM observation further reveals that GAGO-exposed cells were membrane compromised.

Conclusion

In summary, the present study indicates the antibacterial potential of GAGO against MRSA strains, but further study is warranted to understand the mechanism of action of GAGO and its resistance in MRSA strains.

Antimicrobial Activity of Graphene-Based Nanocomposites: Synthesis, Characterization, and Their Applications for Human Welfare

Graphene (GN)-related nanomaterials such as graphene oxide, reduced graphene oxide, quantum dots, etc., and their composites have attracted significant interest owing to their efficient antimicrobial properties and thus newer GN-based composites are being readily developed, characterized, and explored for clinical applications by scientists worldwide. The GN offers excellent surface properties, i.e., a large surface area, pH sensitivity, and significant biocompatibility with the biological system. In recent years, GN has found applications in tissue engineering owing to its impressive stiffness, mechanical strength, electrical conductivity, and the ability to innovate in two-dimensional (2D) and three-dimensional (3D) design. It also offers a photothermic effect that potentiates the targeted killing of cells via physicochemical interactions. It is generally synthesized by physical and chemical methods and is characterized by modern and sophisticated analytical techniques such as NMR, Raman spectroscopy, electron microscopy, etc. A lot of reports show the successful conjugation of GN with existing repurposed drugs, which improves their therapeutic efficacy against many microbial infections and also its potential application in drug delivery. Thus, in this review, the antimicrobial potentialities of GN-based nanomaterials, their synthesis, and their toxicities in biological systems are discussed.

pH-Responsive PVA-Based Nanofibers Containing GO Modified with Ag Nanoparticles: Physico-Chemical Characterization, Wound Dressing, and Drug Delivery

Site-specific drug delivery and carrying repairing agents for wound healing purposes can be achieved using the intertwined three-dimensional structure of nanofibers. This study aimed to optimize and fabricate poly (vinyl alcohol) (PVA)-graphene oxide (GO)-silver (Ag) nanofibers containing curcumin (CUR) using the electrospinning method for potential wound healing applications. Fourier Transform Infrared (FTIR) spectrophotometry, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Dynamic Light Scattering (DLS), and zeta potential were used to characterize the nanostructures. The mechanical properties of the nanostructures were subsequently examined by tensile strength and elongation test. As shown by MIC analysis of E. coli and S. aureus bacteria, the fabricated nanofibers had superior inhibitory effects on the bacteria growth. Ag nanoparticles incorporation into the nanofibers resulted in increased loading and encapsulation efficiencies from 21% to 56% and from 61% to 86%, respectively. CUR release from PVA/GO-Ag-CUR nanofiber at pH 7.4 was prevented, while the acidic microenvironment (pH 5.4) increased the release of CUR from PVA/GO-Ag-CUR nanofiber, corroborating the pH-sensitivity of the nanofibers. Using the in vitro wound healing test on NIH 3T3 fibroblast cells, we observed accelerated growth and proliferation of cells cultured on PVA/GO-Ag-CUR nanofibers.

Three-Dimensional Reduced Graphene Oxide Hybrid Nano-Silver Scaffolds with High Antibacterial Properties

In recent years, hazardous wastewater treatment has been a complex and global problem. In this work, by considering the antimicrobial activity of Ag nanoparticles (AgNPs) and reduced graphene oxide (rGO), we constructed an antibacterial device (G-AgNP) with AgNPs conformably deposited onto a 3D scaffold of reduced graphene oxide in situ. The major limitation, which is difficult to recycle, of two-dimensional graphene-silver composite materials in previous studies is improved. Characterization techniques, SEM, TEM, XRD, and XPS, confirmed the synthesis of nanocomposites. Attributed to its larger specific area, more active sites, and synergistic enhancement, the G-AgNP device demonstrated the best bacterial removal capacity, with an antibacterial rate for both E. coli and S. aureus as high as 100% at quite low AgNP contents. The reported G-AgNP has potential application as a wearable sewage treatment device and for the protection of wearable sensors as a promising sterilizing candidate based on its high and stable antibacterial efficiency.

Nanohybrids of oxides nanoparticles-chitosan and their antimicrobial properties

Growing international problem with pathogens acquiring resistance to antibiotics is the reason for the search for bactericidal substances against which microorganisms cannot become resistant. The aim of this study was to synthesize inorganic-organic nanohybrids and obtain materials with antimicrobial effects. Chitosan (CS) was deposited on nanocomposite carriers such as calcium oxide with titanium dioxide (CaO-TiO₂), magnesium oxide with titanium dioxide (MgO-TiO₂) and copper(II) oxide with titanium dioxide (CuO-TiO₂). The efficiency of the process was examined at varying concentrations of chitosan and temperature. The parameters for nanohybrids synthesis were selected based on the highest amount of nano-chitosan deposited on the nanohybrids-for each carrier, the process conditions were as follows: chitosan solution at 5 g l^-1and 20 °C. The materials were obtained using these parameters and were used for microbiological tests againstE. coliATCC 25922,S. aureusATCC 25923 andC. albicansATCC 10231. The growth inhibitory activity of the obtained materials was qualitatively defined. These results suggest that the synthesized nanohybrids and nanocomposites exhibit biostatic action. The material with the broadest effect was the CuO-TiO₂-CS hybrid, which had biostatic properties against all tested strains at a minimal concentration of 1250μg ml^-1. Further research is required to find eco-friendly, non-toxic, and more effective antimicrobials with a broad action to prevent the acquisition of resistance.

Green Production of Functionalized Few-Layer Graphene-Silver Nanocomposites Using Gallnut Extract for Antibacterial Application

Recently, there has been much attention paid to functionalized few-layer graphene (FFG) owing to its many biomedical applications, such as in bioimaging, biosensors, drug delivery, tissue scaffolds, nanocarriers, etc. Hence, the preparation of FFG has now become of great interest to researchers. The present study systematically investigates the utilization of gallnut extract (GNE) during the process of high-shear exfoliation for the efficient conversion of expanded graphite to FFG. Various parameters, such as GNE concentration, graphite concentration, exfoliation time, and the rotation speed of the high-shear mixer, were initially optimized for FFG production. The prepared FFG was characterized in terms of surface functionality and morphology using Raman spectra, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy, and scanning electron microscopy analyses. Further, the conjugation of FFG with Ag was confirmed by XRD, XPS, and energy-dispersive X-ray spectra. The Ag-FFG composite exhibited antibacterial activity against both Gram-positive and Gram-negative bacteria through the agar well diffusion method. This study provides an efficient, economical, and eco-friendly FFG and Ag-FFG production method for biomedical applications.

Graphene Oxide (GO) Materials-Applications and Toxicity on Living Organisms and Environment

Graphene-based materials have attracted much attention due to their fascinating properties such as hydrophilicity, high dispersion in aqueous media, robust size, high biocompatibility, and surface functionalization ability due to the presence of functional groups and interactions with biomolecules such as proteins and nucleic acid. Modified methods were developed for safe, direct, inexpensive, and eco-friendly synthesis. However, toxicity to the environment and animal health has been reported, raising concerns about their utilization. This review focuses primarily on the synthesis methods of graphene-based materials already developed and the unique properties that make them so interesting for different applications. Different applications are presented and discussed with particular emphasis on biological fields. Furthermore, antimicrobial potential and the factors that affect this activity are reviewed. Finally, questions related to toxicity to the environment and living organisms are revised by highlighting factors that may interfere with it.

Preparation and characterisation of ciprofloxacin-loaded silver nanoparticles for drug delivery

Silver nanoparticles (AgNPs) have shown potential applications in drug delivery. In this study, the AgNPs was prepared from silver nitrate in the presence of alginate as a capping agent. The ciprofloxacin (Cipro) was loaded on the surface of AgNPs to produce Cipro-AgNPs nanocomposite. The characteristics of the Cipro-AgNPs nanocomposite were studied by X-ray diffraction (XRD), UV-Vis, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Fourier-transform infra-red analysis (FT-IR) and zeta potential analyses. The XRD of AgNPs and Cipro-AgNPs nanocomposite data showed that both have a crystalline structure in nature. The FT-IR data indicate that the AgNPs have been wrapped by the alginate and loaded with the Cipro drug. The TEM image showed that the Cipro-AgNPs nanocomposites have an average size of 96 nm with a spherical shape. The SEM image for AgNPs and Cipro-AgNPs nanocomposites confirmed the needle-lumpy shape. The zeta potential for Cipro-AgNPs nanocomposites exhibited a positive charge with a value of 6.5 mV. The TGA for Cipro-AgNPs nanocomposites showed loss of 79.7% in total mass compared to 57.6% for AgNPs which is due to the Cipro loaded in the AgNPs. The release of Cipro from Cipro-AgNPs nanocomposites showed slow release properties which reached 98% release within 750 min, and followed the Hixson-Crowell kinetic model. In addition, the toxicity of AgNPs and Cipro-AgNPs nanocomposites was evaluated using normal (3T3) cell line. The present work suggests that Cipro-AgNPs are suitable for drug delivery.

The Application of Modified SBA-15 as a Chemosensor

:

The Santa Barbara Amorphous (SBA-15), with a large surface area covered with abundant Si-OH active groups on the walls of its pores, can be modified with various organic compounds to build organic-inorganic hybrid materials, which can be used as a catalyst in organic reactions, drug delivery systems, nano sorbent due to its high capacity for removing heavy metals in waste water and as chemosensors for ions. Tunable and straight channels of SBA-15 facilitate the entrance and diffusion of ions through the channels. This paper presents a review of the past five years of literature covering the application of SBA-15 as an ions chemosensor in the liquid and gaseous media.

Effect of Silver Nanoparticles (AgNPs) on Candida Albicans, Candida Dubliniensis, and Candida Guilliermondii

Background:

Candida species are the most important fungal pathogens and are sometimes considered the fourth most common cause of infection in hospitals. Today, research needs to be conducted on the antifungal effect of silver nanoparticles (AgNPs) due to toxicity, side effects, and drug interactions of antifungal chemical drugs.

Objective:

Therefore, this study was done to evaluate the antifungal activity of AgNPs on Candida albicans, Candida dubliniensis, and Candida guilliermondii.

Methodology:

Antifungal activity of AgNPs on Candida albicans, Candida dubliniensis, and Candida guilliermondii was assessed by agar and macrodilution diffusion methods in an in-vitro investigation. Structural changes were investigated by scanning electron microscope (SEM). Then, the obtained data were evaluated by SPSS statistical software.

Results:

Based on the results, the mean diameter of growth inhibition halos by AgNPs was equal to 20, 20.2, and 40.7mm for Candida albicans, Candida dubliniensis, and Candida guilliermondii, respectively. The minimum inhibitory concentrations (MIC) equal 62.50, 31.25, and 15.62 mg/ml for Candida albicans, Candida dubliniensis, and Candida guilliermondii, respectively. The minimum fungicidal concentrations (MFC) were equal to 125, 62.50, and 31.25 mg/ml for Candida albicans, Candida dubliniensis, and Candida guilliermondii, respectively.

Conclusion:

Our results revealed that AgNPs inhibit the growth of Candida albicans, Candida dubliniensis, and Candida guilliermondii. SEM observations also showed that NPs disrupted cell membrane/wall. Changes in yeast levels from smooth to uneven were also observed.

Effects of nanofertilizers on soil and plant-associated microbial communities: Emerging trends and perspectives

Modern agricultural practices are relying excessively upon the use of synthetic fertilizers to supply essential nutrients to promote crop productivity. Though useful in the short term, their prolonged and persistent applications are harmful to soil fertility and nutrient dynamics of the rhizospheric microbiome. The application of nanotechnology in form of nanofertilizer provides an innovative, efficient, and eco-friendly alternative to synthetic fertilizers. The nanofertilizers allow a slow and sustained release of nutrients that not only supports plant growth but also conserve the diversity of the beneficial microbiome. Such attributes may help the phytomicrobiome to efficiently mitigate both biotic and abiotic stress conditions. Unfortunately, despite, exceptional efficiency and ease of applications, certain limitations are also associated with the nanofertilizers such as their complicated production process, tenuous transport and dosage-sensitive efficiency. These bottlenecks are causing a delay in the large-scale applications of nanofertilizers in agriculture. This review aims to highlight the current trends and perspectives on the use of nanofertilizers for improving soil fertility with a special focus on their effects on beneficial phyromicrobiome.