Ampicillin detection using absorbance biosensors utilizing Mn-doped ZnS capped with chitosan micromaterials.

The detection of ampicillin plays a crucial role in managing and monitoring its usage and resistance. This study introduces a simple and effective biosensor for ampicillin detection, utilizing the unique absorbance features of Mn-doped ZnS capped by chitosan micromaterials in conjunction with ß-lactamase activity. The biosensors can detect ampicillin concentrations from 13.1 to 72.2 µM, with a minimum detection limit of 2.93 µM for sensors based on 300 mg/L of the sensing material. In addition, these sensors show high specificity for ampicillin over other antibiotics such as penicillin, tetracycline, amoxicillin, cephalexin, and a non-antibiotic-glucose. This specificity is demonstrated by an enhancing effect when beta-lactamase is used, as opposed to a quenching effect observed at 340 nm in the absorbance spectrum when no beta-lactamase is present. This research highlights the potential of affordable chitosan-capped Mn-doped ZnS micromaterials for detecting ampicillin through simple absorbance measurements, which could improve the monitoring of antibiotics in both clinical and environmental settings.

Dual-channel fluorescent sensors based on chitosan-coated Mn-doped ZnS micromaterials to detect ampicillin.

The global threat of antibiotic resistance has increased the importance of the detection of antibiotics. Conventional methods to detect antibiotics are time-consuming and require expensive specialized equipment. Here, we present a simple and rapid biosensor for detecting ampicillin, a commonly used antibiotic. Our method is based on the fluorescent properties of chitosan-coated Mn-doped ZnS micromaterials combined with the ß-lactamase enzyme. The biosensors exhibited the highest sensitivity in a linear working range of 13.1-72.2 pM with a limit of detection of 8.24 pM in deionized water. In addition, due to the biological specificity of ß-lactamase, the proposed sensors have demonstrated high selectivity over penicillin, tetracycline, and glucose through the enhancing and quenching effects at wavelengths of 510 nm and 614 nm, respectively. These proposed sensors also showed promising results when tested in various matrices, including tap water, bottled water, and milk. Our work reports for the first time the cost-effective (Mn:ZnS)Chitosan micromaterial was used for ampicillin detection. The results will facilitate the monitoring of antibiotics in clinical and environmental contexts.

Bacillus subtilis DNA fluorescent sensors based on hybrid MoS2 nanosheets.

Although sensor technology has advanced with better materials, biomarkers, and fabrication and detection methods, creating a rapid, accurate, and affordable bacterial detection platform is still a major challenge. In this study, we present a combination of hybrid-MoS2 nanosheets and an amine-customized probe to develop a fast, sensitive biosensor for Bacillus subtilis DNA detection. Based on fluorescence measurements, the biosensor exhibits a detection range of 23.6-130 aM, achieves a detection limit of 18.7 aM, and was stable over four weeks. In addition, the high selectivity over Escherichia coli and Vibrio proteolyticus DNAs of the proposed Bacillus subtilis sensors is demonstrated by the fluorescence quenching effect at 558 nm. This research not only presents a powerful tool for B. subtilis DNA detection but also significantly contributes to the advancement of hybrid 2D nanomaterial-based biosensors, offering substantial promise for diverse applications in biomedical research and environmental monitoring.

Microstructure and Mechanical Properties of Butt Joints between Stainless Steel SUS304L and Aluminum Alloy A6061-T6 by TIG Welding.

The tungsten inert gas (TIG) welding method most commonly used to weld ferrous metals, nonferrous metals, and other metals since it is simple, easily implemented, and achieves consistent high-quality welds. In this study, butt joints produced between aluminum alloy A6061-T6 and stainless steel SUS304L have been achieved by using TIG welding with ER4047 filler metal. The macrostructure and microstructure of the resulting specimens were analyzed by means of an optical microscope (OM), a scanning electron microscope (SEM), and an energy dispersive X-ray spectrometer (EDS). A uniform intermetallic layer was found at the interface between the stainless steel and the weld seam having a thickness of 2 µm, and the intermetallic compound (IMC) includes Fe4Al13, Fe2Al5, and FeAl3 phases. The micro-hardness and tensile strength of the weld joints were also investigated. Due to Si content in the compensating metal, there was a prevention of iron diffusion into the aluminum, thus hindering the development of the IMC layer and reducing its thickness in such a way that the weld joint strength increases. The analyzed results show that the average micro-hardness of the stainless steel, weld seam, aluminum alloys, and IMC layer were 218 HV, 88.3 HV, 63.3 HV, and 411 HV, respectively. The fracture occurred at the brazed interface, and the ultimate tensile strength value reached 225 MPa.