In this work, the kinetics of the redox reaction between platinum(IV) chloride complex ions and ascorbic acid is studied. The reduction process of Pt(IV) to Pt(II) ions was carried out at different reagent concentrations and environmental conditions, i.e., pH (2.2–5.1), temperature (20–40 °C), ionic strength (I = 0.00–0.40 M) and concentrations of chloride ions (0.00–0.40 M). The kinetic traces during the reduction process were registered using stopped-flow spectrophotometry. Based on the kinetic traces, the rate constants were determined, and the kinetic equations were proposed. It was shown that in the mild acidic medium (pH = 2.5), the reduction process of Pt(IV) to Pt(II) ions is more complex in the presence of oxygen dissolved in the aqueous solutions. For these processes, the values of the enthalpy and entropy of activation were determined. Moreover, the mechanism of the reduction of Pt(IV) to Pt(II) ions was proposed. The presented results give an overview of the process of the synthesis of platinum nanoparticles in the solution containing oxygen, in which the reduction process of Pt(IV) to Pt(II) ions is the first step.

Introduction: Gonorrhea is the second most common bacterial sexually transmitted disease after chlamydiosis, and its incidence in both Europe and the United States has been increasing recently. Treatment of gonorrhea is made more difficult by the increasing resistance of the causative agent, Neisseria gonorrhoeae to antibiotics. Resistance to penicillin and, in particular, the production of beta-lactamase has led to the discontinuation of penicillin in the treatment of gonorrhea. However, monitoring the production of this enzyme is still important if only as part of the characterization of individual strains and because of the potential risk of extended-spectrum beta-lactamases in N. gonorrhoeae. Objective: To investigate the production of beta-lactamase in N. gonorrhoeae isolated from patients of the Department of Dermatology and Venereology of the Medical University of Warsaw in 2010-2020. Material and methods: A total of 1997 N. gonorrhoeae isolates routinely cultured from outpatients of the Department of Dermatology and Venereology, Medical University of Warsaw, from 2010 to 2020 were examined. Cefinase assay was used to test for the presence of beta-lactamase. Results: Beta-lactamase was produced by an average of 5.66% of the isolates tested. A significant increase in the percentage of strains producing this enzyme, to a maximum of 18.8%, was observed in 2018, with a sharp decline in subsequent years. In 2020, beta-lactamase was produced by 0% of the strains tested. Conclusions: The percentage of N. gonorrhoeae strains that produce beta-lactamase shows a high variability over time, which is probably related to the spread of strains belonging to different genogroups and differing significantly from one another.