In this study, the titanium–gadolinium quantum dots (TGQDs) were novel, first of its type to be synthesized, and fully characterized to date. Multiple physical characterization includes scanning electron microscopy (SEM), scanning electrochemical microscope (SCEM), x-ray fluorescence, spectrophotometry, and dynamic light scattering were carried out. The obtained results confirmed appropriate size and shape distributions in addition to processing optical features with high quantum yield. The synthesized TGQD was used as a fluorescent dye for bacterial detection and imaging by fluorescent microscopy and spectrophotometry, where TGQD stained only bacterial cells, but not human cells. The significant antibacterial activities of the TGQDs were found against a highly pathogenic bacterium (Staphylococcus aureus) and its antibiotic resistant strains (vancomycin and methicillin resistant Staphylococcus aureus) using growth curve analysis and determination of minimum inhibitory concentration (MIC) analysis. Live/dead cell imaging assay using phase-contrast microscope was performed for further confirmation of the antibacterial activity. Cell wall disruption and release of cell content was observed to be the prime mode of action with the reduction of cellular oxygen demand (OD).

In this article, construction of amperometric sensor(s) based on screen-printed carbon electrodes covered by thin layers of two types of carbon nanomaterials serving as amplifiers, and containing [Cu(bipy)₂Cl]Cl∙5H₂O complex is reported. Their performance and biomimetic activity towards two selected neurotransmitters (dopamine and serotonin) was studied mainly using flow injection analysis (FIA). The important parameters of FIA such as working potential, flow rate, and pH were optimized. The mechanism of the catalytic activity is explained and experimentally confirmed. It reveals that presence of hydrogen peroxide plays a crucial role which leads to answer the title question: can presented complex really be considered as a tyrosinase biomimetic catalyst or only as a redox mediator?

Heptamethine cyanines are a well-known class of organic near-infrared (NIR) fluorophores that play an indispensable role in chemistry and biology. Despite their ubiquity, the underlying photophysical and photochemical dynamics triggered by excitation remain surprisingly elusive. In this study, we investigated a prototypical heptamethine cyanine ( Cy7 ) using femtosecond stimulated Raman spectroscopy. Combining transient Raman spectra with quantum chemical calculations allowed us to develop a comprehensive picture of the species produced during Cy7 excitation and their behavior on the fs to sub-ms time scale. We have unambiguously identified the excited singlet and triplet states and the resulting configurational photoisomers using clearly distinguishable Raman shifts. We also reveal solvent-mediated relaxation channels, in particular ultrafast photoinduced electron transfer to dissolved oxygen, generating cyanine radical dication in addition to superoxide. Together, these insights provide a coherent mechanistic framework for Cy7 photodynamics and provide design guidance for next-generation NIR probes.