Effect of reduced graphene oxide-hybridized ZnO thin films on the photoinactivation of Staphylococcus aureus and Salmonella enterica serovar Typhi

Graphene materials: Armor against nosocomial infections and biofilm formation - A review

Graphene has revolutionized the field of energy and storage sectors. Out of the total number of nosocomial infections diagnosed all around the world, the majority of the cases (around 70%) are found to be due to the medical device or assistance utilized while treating the patient. Combating these diseases is vital as they cause a nuisance to the patients and medical practitioners. Coatings of graphene and its derivatives hold the key to the formation of special surfaces that can rupture microbial cells using their sharp edges, ultimately leading to nuclear and cellular fragmentation. Their incorporation as a whole or as a part in the hospital apparel and the medical device has aided medical practitioners to combat many nosocomial diseases. Graphene is found to be highly virulent with broad-spectrum antimicrobial activity against nosocomial strains and biofilm formation. Their alternate mode of action like trapping and charge transfer has also been discussed well in the present review. The various combinational forms of graphene with its conjugates as a suitable agent to combat nosocomial infections and a potential coating for newer challenges like COVID-19 infections has also been assessed in the current study. Efficiency of graphene sheets has been found to be around 89% with a reaction time as less as 3 h. Polymers with graphene seem to have a higher potency against biofilm formation. When combined with graphene oxide, silver nanoparticles provide 99% activity against nosocomial pathogens. In conclusion, this review would be a guiding light for scientists working with graphene-based coatings to unfold the potentials of this marvelous commodity to tackle the present and future pandemics to come.

Graphene-Based Antimicrobial Biomedical Surfaces

Biomedical application of graphene derivatives have been intensively studied in last decade. With the exceptional structural, thermal, electrical, and mechanical properties, these materials have attracted immense attention of biomedical scientists to utilize graphene derivatives in biomedical devices to improve their performance or to achieve desired functions. Surfaces of graphene derivatives including graphite, graphene, graphene oxide and reduce graphene oxide have been demonstrated to pave an excellent platform for antimicrobial behavior, enhanced biocompatibility, tissue engineering, biosensors and drug delivery. This review focuses on the recent advancement in the research of biomedical devices with the coatings or highly structured polymer nanocomposite surfaces of graphene derivatives for antimicrobial activity and sterile surfaces comprising an entirely new class of antibacterial materials. Overall, we aim to highlight on the potential of these materials, current understanding and knowledge gap in the antimicrobial behavior and biocompatibility to be utilized of their coatings to prevent the cross infections.

Antimicrobial Activity of Zinc Oxide Nano/Microparticles and Their Combinations against Pathogenic Microorganisms for Biomedical Applications: From Physicochemical Characteristics to Pharmacological Aspects

Zinc oxide (ZnO) nano/microparticles (NPs/MPs) have been studied as antibiotics to enhance antimicrobial activity against pathogenic bacteria and viruses with or without antibiotic resistance. They have unique physicochemical characteristics that can affect biological and toxicological responses in microorganisms. Metal ion release, particle adsorption, and reactive oxygen species generation are the main mechanisms underlying their antimicrobial action. In this review, we describe the physicochemical characteristics of ZnO NPs/MPs related to biological and toxicological effects and discuss the recent findings of the antimicrobial activity of ZnO NPs/MPs and their combinations with other materials against pathogenic microorganisms. Current biomedical applications of ZnO NPs/MPs and combinations with other materials are also presented. This review will provide the better understanding of ZnO NPs/MPs as antibiotic alternatives and aid in further development of antibiotic agents for industrial and clinical applications.

Synthesis, Characterization, and Photocatalytic Performance of ZnO–Graphene Nanocomposites: A Review

ZnO is an exciting material for photocatalysis applications due to its high activity, easy accessibility of raw materials, low production costs, and nontoxic. Several ZnO nano and microstructures can be obtained, such as nanoparticles, nanorods, micro flowers, microspheres, among others, depending on the preparation method and conditions. ZnO is a wide bandgap semiconductor presenting massive recombination of the generated charge carriers, limiting its photocatalytic efficiency and stability. It is common to mix it with metal, metal oxide, sulfides, polymers, and nanocarbon-based materials to improve its photocatalytic behavior. Therefore, ZnO–nanocarbon composites formation has been a viable alternative that leads to new, more active, and stable photocatalytic systems. Mainly, graphene is a well-known two-dimensional material, which could be an excellent candidate to hybridize with ZnO due to its excellent physical and chemical properties (e.g., high specific surface area, optical transmittance, and thermal conductivity, among others). This review analyses ZnO–graphene nanocomposites’ recent advances, addressing the synthesis methods and the resulting structural, morphological, optical, and electronic properties. Moreover, we examine the ZnO–graphene composites’ role in the photocatalytic degradation of organic/inorganic pollutants.

The Influence of Deposition Time on the Structural, Morphological, Optical and Electrical Properties of ZnO-rGO Nanocomposite Thin Films Grown in a Single Step by USP

Thin films of nanocomposite of zinc oxide–reduced graphene oxide (ZnO-rGO) deposited on soda-lime glass substrates were prepared using ultrasonic spray pyrolysis (USP) at 460 °C. The preparation process does not use harsh acids and is environmentally friendly. The deposition period of 2, 3.5 and 5 min resulted in compact, uniform samples with thicknesses of 148, 250 and 365 nm, respectively. After performing structural, morphological, optical and electrical characterization of the prepared nanocomposite, an influence of the deposition time on the physical properties of the obtained films was determined. TEM analyses indicate that the ZnO-rGO nanocomposite presents ZnO nanoparticles anchored on graphene sheets, while XRD, X-ray Photoelectron Spectroscopy (XPS) and Raman results show the presence of a ZnO phase in the ZnO-rGO films. HR-SEM studies showed changes of the ZnO-rGO thin films morphology due to the incorporation of graphene into the ZnO films. Here, the particles of ZnO are similar to small grains of rice and graphene films have the appearance of a little “rose”. As the thickness of the film increases with deposition time, it reduces the structure of resistance of the nanocomposite thin films to 135 Ω. In addition, the optical transmission of the thin films in the visible region resulted affected. Here, we report a simple methodology for the preparation of ZnO-rGO nanocomposite thin films.

Graphene Oxide-Assisted Morphology and Structure of Electrodeposited ZnO Nanostructures

In this paper, ZnO electrodeposition was studied with the presence of graphene oxide (GO) exploited as a possible structure-directing agent. The effect of deposition potential and duration on the morphology and structure of ZnO was analyzed. The morphology and structure of the hybrids was analyzed by Raman spectroscopy, X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM). The Raman results indicate a successful modification of ZnO with GO sheets and a hybridization threshold of 10 mg L⁻¹ by the evolution of the defect related band of ZnO at 580 cm⁻¹. The morphology results show that a low GO content only slightly influences the morphology and orientation of ZnO nanostructures while a high content as 10 mg L⁻¹ changes the morphology in nanoplates and growth orientation to lateral. The results show that while GO participated in the deposition reaction, it has a two-fold role, also by structure-controlling ZnO, indicating that the approach is valid for the use of GO as a structure-directing agent for the fabrication of ZnO nanostructures by electrodeposition with varying morphologies and orientations.

Photo-triggered antibacterial and anticancer activities of zinc oxide nanoparticles

ZnO nanoparticles (ZnO NPs) have gained more attention in recent years due to their ability to induce the generation of reactive oxygen species (ROS) under light irradiation. Photo-triggered ROS generation by ZnO NPs and the resulting phototoxicity in cells have found use in antibacterial and anticancer applications. This review highlights recent advances in the development of ZnO NPs and hybrid-type functionalized ZnO NPs for photo-triggered antibacterial and anticancer activities. In addition, various chemical modifications including metal doping, metal hybridization, modification with polymers, and sensitization by organic photosensitizers have been further introduced to enhance the photocatalytic efficiency and ROS generation capability of ZnO NPs. The enhanced ROS generation efficiency of modified ZnO NPs consequently increases their antibacterial and anticancer activities. Additionally, we offer some insights into the design and engineering of next-generation ZnO NPs for more effective antibacterial and anticancer applications.

Recent advances in nanomaterials for water protection and monitoring

Nanomaterials (NMs) for adsorption, catalysis, separation, and disinfection are scrutinized. NMs-based sensor technologies and environmental transformations of NMs are highlighted.