Decontamination Effect of Hypochlorous Acid Dry Mist on Selected Bacteria, Viruses, Spores, and Fungi as Well as on Components of Electronic Systems.

This publication presents the effect of hypochlorous acid dry mist as a disinfectant on selected bacteria, viruses, spores, and fungi as well as on portable Microlife OXY 300 finger pulse oximeters and electronic systems of Raspberry Pi Zero microcomputers. The impact of hypochlorous acid on microbiological agents was assessed at concentrations of 300, 500, and 2000 ppm of HClO according to PN-EN 17272 (Variant I). Studies of the impact of hypochlorous acid fog on electronic components were carried out in an aerosol chamber at concentrations of 500 ppm and 2000 ppm according to two models consisting of 30 (Variant II) and 90 fogging cycles (Variant III). Each cycle included the process of generating a dry mist of hypochlorous acid (25 mL/m3), decontamination of the test elements, as well as cleaning the chamber of the disinfectant agent. The exposure of the materials examined on hypochlorous acid dry mist in all variants resulted in a decrease in the number of viruses, bacteria, spores, and fungi tested. In addition, the research showed that in the variants of hypochlorous acid fogging cycles analyzed, no changes in performance parameters and no penetration of dry fog of hypochlorous acid into the interior of the tested medical devices and electronic systems were observed.

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.

Laser Emission Spectroscopy of Graphene Oxide Deposited on 316 Steel and Ti6Al4V Titanium Alloy Suitable for Orthopedics.

This paper presents the results of an analysis of carbon (in the form of graphene oxide) deposited on the surface of threads made from stainless steel 316 and titanium alloy Ti6Al4V used in orthopedics using Laser Induced Breakdown Spectroscopy (LIBS). The aim of the article is to indicate the possibility of using the LIBS spectra for the study of thin layers, including graphene derivatives and other elements. Stratigraphic measurements allowed the detection of differences in the spectra peaks of individual elements, not only in the surface layer itself and in the native material, but also in the intermediate layer connecting the two layers. Due to the clear difference in the outline of the spectrum of graphene oxide and the spectrum of the native material of the samples analyzed, a clear incorporation of carbon atoms into the surface layer was observed. A factor analysis was performed, which confirmed the incorporation of graphene oxide into the surface layer of the native material of the elements examined.

Studies on the Effect of Graphene Oxide Deposited on Gold and Nickel Microsieves on Prostate Cancer Cells DU 145.

This work shows the effect of graphene oxide deposition on microsieves' surfaces of gold and nickel foils, on DU 145 tumor cells of the prostate gland. The sieves were made by a laser ablation process. The graphene oxide (GO) deposition process was characterized by the complete covering of the inner edges of the microholes and the flat surface between the holes with GO. Electron microscanning studies have shown that due to the deposition method applied, graphene oxide flakes line the interior of the microholes, reducing the unevenness of the downstream surfaces during the laser ablation process. The presence of graphene oxide was confirmed by Fourier infrared spectroscopy. During the screening (sieving) process, the microsieves were placed in a sieve column. Gold foil is proven to be a very good material for the screening of cancer cells, but even more so after screening as a substrate for re-culture of the DU 145. This allows a potential recovery of the cells and the development of a targeted therapy. The sieved cells were successfully grown on the microsieves used in the experiment. Graphene oxide remaining on the surface of the nickel sieve has been observed to increase the sieving effect. Although graphene oxide improved separation efficiency by 9.7%, the nickel substrate is not suitable for re-culturing of the Du 145 cells and the development of a targeted therapy compared to the gold one.

Fatigue Life of Austenitic Steel 304 Bolts Strengthened by Surface Treatment with Graphene Oxide Layer and Surface Shot Peening.

This paper presents the results of investigations of the effect of graphene oxide and surface shot peening on the mechanical properties and fatigue life of bolts made of austenitic 304 steel. An innovative method for the uniform deposition of graphene oxide on screws is presented. The process involved activating the surface using plasma and then performing graphene oxide deposition using centrifugal force and vacuum drying. The screw specimens prepared in this way were subjected to a surface peening process. Comparative studies have shown that the combination of graphene oxide deposition and shot peening processes results in an increase in fatigue life of approximately 42 ÷ 275% (depending on the stress amplitude level) compared to the as-delivered samples. The results presented are promising and may provide a basis for further research on the application of graphene and its derivatives to increase fatigue life and improve the mechanical properties of machine components.

Study on the Effect of Deposited Graphene Oxide on the Fatigue Life of Austenitic Steel 1.4541 in Different Temperature Ranges.

This paper presents the effect of deposited graphene oxide coating on fatigue life of austenitic steel 1.4541 at 20 °C, 100 °C, and 200 °C. The study showed a decrease in the fatigue life of samples with a deposited graphene oxide layer in comparison with reference samples at 20 °C and 100 °C. However, an increase in fatigue life of samples with a deposited graphene oxide layer in comparison with reference samples occurred at 200 °C. This relationship was observed for the nominal stress amplitude of 370 and 420 MPa. Measurements of temperature during the tensile failure of the sample and microfractographic analysis of fatigue fractures were performed. Tests have shown that graphene oxide deposited on the steel surface provides an insulating layer. A higher temperature of the samples with a deposited graphene oxide layer was observed during fracture compared to the reference samples.

Graphene Oxide Aerosol Deposition and its Influence on Cancer Cells. Preliminary Results.

This paper presents the results of the interaction of graphene oxide (GO) on MDA-MB-231 and SW-954 cancer cell lines. The tests were carried out in two variants. In the first one, GO was sprayed on a Petri dish and then, the cancer cell lines were cultured. In the second variant, the cells were covered with an aerosol containing GO. In both variants, cancer cell lines were incubated and tested every 24, 48, and 72 h. After each time period, cell viability and surface morphology were measured. The tests after 72 h showed that coating with GO aerosol caused a reduction in cell viability by 52.7% and 26.4% for MDA-MB-231 and SW-954 cancer cell lines, respectively, with respect to a reference sample (without the influence of GO aerosol). Tests where GO is a culture medium demonstrated a decrease in cell viability by approximately 4.3% compared to a reference sample for both considered cell lines.

The Influence of Laser Ablation Parameters on the Holes Structure of Laser Manufactured Graphene Paper Microsieves.

The graphene paper microsieves can be applied in the filtration of biological fluids or separation of solid particles from exploitation fluids. To produce graphene paper microsieves for specific applications, good control over fabrication should be achieved. In this study, a laser ablation method using a picosecond laser was applied to fabricate graphene paper microsieves. Holes in the microsieves were drilled using pulsed laser radiation with a pulse energy from 5 to 100 µJ, a duration of 60 ps, a wavelength of 355 nm, and a repetition rate of 1 kHz. The impact method was applied using 10 to 100 pulses to drill one hole. To produce holes of a proper diameter which could separate biological particles of a certain size (≥10 µm), optimum parameters of graphene paper laser ablation were defined using the MATLAB software taking into account laser pulse energy, repetition rate, and a desired hole diameter. A series of structural tests were carried out to determine the quality of an edge and a hole shape. Experimental results and Laguerre-Gauss calculations in MATLAB were then compared to perform the analysis of the distribution of diffraction fringes. Optimum experimental parameters were determined for which good susceptibility of the graphene paper to laser processing was observed.