With the rapid and continuous emergence of antimicrobial resistance, bacterial infections became a significant global healthcare concern. One of the proposed strategies to combat multidrug-resistant pathogens is to use additional compounds, such as natural biologically active substances, as adjuvants for existing antibiotics. In this study, we investigated the potential of caffeine, the widely consumed alkaloid, to modulate the antibacterial effects of antibiotics commonly used in clinical practice. We used disc diffusion assay to evaluate the effects of caffeine on 40 antibiotics in two Staphylococcus aureus strains (methicillin-resistant and methicillin-sensitive). Based on the results of this step, we selected five antibiotics for which the greatest caffeine-induced improvements in antibacterial activity were observed, and further analyzed their interactions with caffeine using a checkerboard approach. Caffeine at concentrations of 250 µg/mL or higher halved the MIC values of ticarcillin, cefepime, gentamycin, azithromycin, and novobiocin for all gram-negative species investigated (Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter baumannii). At the highest caffeine concentrations tested (up to 16 mg/mL), decreases in MIC values were 8- to 16-fold. The obtained results prove that caffeine modulates the activity of structurally diverse antibiotics, with the most promising synergistic effects observed for cefepime and azithromycin toward gram-negative pathogens.

Cancer is a leading cause of death worldwide, with nearly 10 million fatalities yearly. Consequently, despite the search for new therapeutic approaches, the use of classical chemotherapy, remains one of the main treatment regimens. Therefore, we evaluate the use of platinum nanoparticles (PtNPs) of different sizes as potential modulators of doxorubicin (DOX) activity. In the presented research, we utilized a wide range of methods, including Spectroscopic measurements, Isothermal Titration Calorimetry, Dynamic Light Scattering, and Atomic Force Microscopy, as well as biological assays such as the Ames mutagenicity test on Salmonella enterica serovar Typhimurium TA98 and the alamarBlue cytotoxicity assay with Fluorescent Confocal Microscopy on non-cancerous HaCaT and cancerous MelJuSo cell lines, to investigate the interactions between PtNPs and DOX and the effect of diverse-sized nanoparticles on DOX activity. The obtained results indicate the presence of direct interactions, particularly highlighting differences related to particles size. We confirmed that DOX affects the aggregation of nanoparticles, while the nanoparticles induce DOX fluorescence quenching. In terms of biological aspects, PtNPs reduced the mutagenicity of DOX, and increased the survival of non-cancerous HaCaT cells. Furthermore, 70 nm PtNPs significantly increased DOX effects on cancerous MelJuSo cells by negatively affecting their morphology and culture density. To conclude, our research provided valuable insights into the interactions between PtNPs and DOX with particular emphasis on the nanoparticles' size influence highlighting nanoparticles' impact on DOX cytotoxicity providing a base for further research on the potential future modification in treatment approaches.

Antimicrobial resistance is a major healthcare threat globally. Xanthines, including caffeine and pentoxifylline, are attractive candidates for drug repurposing, given their well-established safety and pharmacological profiles. This study aimed to analyze potential interactions between xanthines and aromatic antibiotics (i.e., tetracycline and ciprofloxacin), and their impact on antibiotic antibacterial activity. UV-vis spectroscopy, statistical-thermodynamical modeling, and isothermal titration calorimetry were used to quantitatively evaluate xanthine-antibiotic interactions. The antibacterial profiles of xanthines, and xanthine-antibiotic mixtures, towards important human pathogens Staphylococcus aureus, Enterococcus faecium, Escherichia coli, Acinetobacter baumannii, Klebsiella pneumoniae, and Enterobacter cloacae were examined. Caffeine and pentoxifylline directly interact with ciprofloxacin and tetracycline, with neighborhood association constant values of 15.8–45.6 M⁻¹ and enthalpy change values up to −4 kJ·M⁻¹. Caffeine, used in mixtures with tested antibiotics, enhanced their antibacterial activity in most pathogens tested. However, antagonistic effects of caffeine were also observed, but only with ciprofloxacin toward Gram-positive pathogens. Xanthines interact with aromatic antibiotics at the molecular and in vitro antibacterial activity level. Given considerable exposure to caffeine and pentoxifylline, these interactions might be relevant for the effectiveness of antibacterial pharmacotherapy, and may help to identify optimal treatment regimens in the era of multidrug resistance.

Graphene oxide (GO), owing to its extraordinary application prospects in biomedicine, is attracting growing research attention. However, the biosafety and blood compatibility of GO required for its clearance for use in clinical trials remain elusive. Therefore, we studied the mutagenic properties of GO as well as its cell toxicity and blood compatibility. Prior to biological experiments, we assessed the structural organization of GO using dynamic light scattering and microscopic visualization methods. The results of both the Ames mutagenicity test performed on Salmonella enterica serovar Typhimurium TA98 and TA102 strains and the cytotoxicity test on noncancerous, immortalized human keratinocytes revealed no mutagenic or toxic effects of GO. Simultaneously, GO reduced the viability of the MelJuSo human melanoma cell line. A blood compatibility assay revealed that a concentration of 10 μg/mL was critical for GO biosafety, as greater concentrations induced diverse side effects. Specifically, GO disrupts erythrocytes’ membranes in the dose-dependent manner. Moreover, GO at higher concentrations both inhibited the process of ADP (a physiological platelet agonist)-induced cell aggregation and affected their disaggregation process in platelet-rich plasma. However, in the blood clotting assessment, GO showed no effects on the activated partial thromboplastin time, prothrombin time, or thrombin time of the platelet-poor plasma. The obtained results clearly indicate that the relationship between the GO preparation method, its size, and concentration and biosafety must be cautiously monitored in the context of further possible biomedical applications.

Cancer is a difficult disease to cure due to its diversity and complexity. Despite novel therapeutic approaches having been proposed in recent years, chemotherapy remains one of the most common treatment regimens to this day. Unfortunately, its anticancer effects are often quelled by the lack of selectivity; hence alteration of the activity of already existing drugs by combining them with potential modulators e.g. metallic nanoparticles has been proposed as a possible strategy to overcome this problem. Herein, we verified if platinum nanoparticles (PtNPs) of various sizes interact with daunorubicin (DAU), a chemotherapeutic agent used for the treatment of leukaemia. Utilizing DLS and NTA we observed nanoparticle aggregation upon addition of increasing concentrations of DAU. Furthermore, we noticed that PtNPs quench DAU's fluorescence, suggesting their direct interaction. Next, we used FTIR and NIR spectroscopies and registered significant changes in the obtained spectra in the presence of PtNPs. The ITC and DSC analyses showed that all tested sizes of PtNPs interact with DAU in an endothermic manner, with the enthalpy change between 0.47 and 4.36 kcal mol⁻¹. The release analysis employing the dialysis bag method evidenced that PtNPs influence DAU's diffusion kinetics, decreasing its release from 100% (when alone) to ca. 70% when combined with PtNPs. All tested sizes of PtNPs reduce DAU's mutagenicity towards S.enterica serovar Typhimurium TA98 strain, however, no significant influence on DAU's cytotoxicity was observed on neither MelJuSo nor HaCaT eukaryotic cell lines. Overall, these results indicate that PtNPs may affect DAU's biological activity and warrant further biological studies.

Background/Objectives: Cancer remains one of the leading causes of death worldwide. Although chemotherapy is widely used, it is associated with severe side effects, including myelosuppression and systemic toxicity. Nanoparticles have emerged as promising candidates for modulating drug activity. In this study, we investigated whether platinum nanoparticles (PtNPs) of various sizes interact with idarubicin (IDA), an anthracycline anticancer drug used primarily to treat acute leukaemia. Methods: Interactions between PtNPs and IDA were analysed using dynamic light scattering (DLS), atomic force microscopy (AFM), fluorescence spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, and near-infrared (NIR) spectroscopy. Thermodynamic and thermal properties were assessed using isothermal titration calorimetry (ITC) and differential scanning calorimetry (DSC). Biological effects were evaluated using the Ames mutagenicity assay on the Salmonella enterica serovar Typhimurium TA98 strain and cytotoxicity assays on SK-BR-3 and MCF-7 cell lines. Results: DLS demonstrated changes in the hydrodynamic diameter of PtNPs following IDA addition, which were further supported by AFM imaging. PtNPs significantly quenched IDA fluorescence, indicating close molecular interactions, which were further supported by FTIR and NIR. ITC revealed that the interactions were endothermic, with enthalpy values ranging from 1.2 to 3.6 kcal/mol, and DSC demonstrated that the PtNP-IDA combination altered the melting temperature of IDA. Biological assays revealed that all examined PtNP sizes influenced IDA mutagenicity in the Salmonella enterica serovar Typhimurium TA98 strain. Furthermore, PtNPs modulated the cytotoxicity of IDA in SK-BR-3 and MCF-7 cell lines in a dose-dependent manner. Conclusions: These findings demonstrate that PtNPs interact with IDA and modulate its biological activity. However, in this study no non-cancerous cell lines were examined; therefore, the observed interactions and biological effects support further investigation of the PtNP-IDA combination in the context of nanoparticle-assisted anticancer therapy on a broader range of in vitro cell lines.