Over the last few years, the development of fluorescent probes has received considerable attention. Fluorescence signaling allows noninvasive and harmless real-time imaging with great spectral resolution in living objects, which is extremely useful for modern biomedical applications. This review presents the basic photophysical principles and strategies for the rational design of fluorescent probes as visualization agents in medical diagnosis and drug delivery systems. Common photophysical phenomena, such as Intramolecular Charge Transfer (ICT), Twisted Intramolecular Charge Transfer (TICT), Photoinduced Electron Transfer (PET), Excited-State Intramolecular Proton Transfer (ESIPT), Fluorescent Resonance Energy Transfer (FRET), and Aggregation-Induced Emission (AIE), are described as platforms for fluorescence sensing and imaging in vivo and in vitro. The presented examples are focused on the visualization of pH, biologically important cations and anions, reactive oxygen species (ROS), viscosity, biomolecules, and enzymes that find application for diagnostic purposes. The general strategies regarding fluorescence probes as molecular logic devices and fluorescence–drug conjugates for theranostic and drug delivery systems are discussed. This work could be of help for researchers working in the field of fluorescence sensing compounds, molecular logic gates, and drug delivery.

The rising incidence of infectious diseases caused by pathogenic microorganisms that exhibit multiple resistances to various groups of antibiotics has prompted many researchers to focus their investigations on alternative and more effective products with lasting antibacterial effects, minimizing the risk of resistance development. This review outlines the key approaches to developing effective antibacterial coatings. It emphasizes the highlights of significant achievements made in recent years, along with future challenges and perspectives in this field. The examples presented illustrate both the application potential and the issues associated with traditional and innovative materials. We hope that this review will inspire researchers to develop effective and practically useful antibacterial coatings.

A novel highly water-soluble 1,8-naphthalimide with pH and viscosity-sensing fluorescence was synthesized and investigated. The synthesized compound was designed as a molecular device in which a molecular rotor and molecular “off-on” switcher were integrated. In order to obtain a TICT driven molecular motion at C-4 position of the 1,8-naphthalimide fluorophore, a 4-methylpiperazinyl fragment was introduced. The molecular motion was confirmed after photophysical investigation in solvents with different viscosity; furthermore, the fluorescence-sensing properties of the examined compound were investigated in 100% aqueous medium and it was found that it could be used as an efficient fluorescent probe for pH. Due to the non-emissive deexcitation nature of the TICT fluorophore, the novel system showed low yellow–green emission, which represented “power-on”/“rotor-on” state. The protonation of the methylpiperazine amine destabilized the TICT process, which was accompanied by fluorescence enhancement indicating a “power-on”/“rotor-off” state of the system. The results obtained clearly illustrated the great potential of the synthesized compound to serve as pH- and viscosity-sensing material in aqueous solution.

A new highly water-soluble 1,8-naphthalimide fluorophore designed on the “fluorophore-spacer-receptor₁-receptor₂” model has been synthesized. Due to the unusually high solubility in water, the novel compound proved to be a selective PET-based probe for the determination of pHs in aqueous solutions and rapid detection of water content in organic solvents. Based on the pH dependence of the probe and its high water solubility, the INH logic gate was achieved using NaOH and water as chemical inputs, where NaOH is the disabler and the water is an enabler. In addition, the probe showed effective fluorescence “off-on” reversibility on glass support after exposure to acid and base vapors, which defines it as a promising platform for rapid detection of acid/base vapors in the solid-state, thus extending the molecular sensing concept from solution to the solid support.

In the last few decades, photoinduced electron transfer (PET) based on “fluorophore-spacer-receptor” format became the most popular approach in the design of fluorescent sensing probes. As a result, a variety of architectures for detection of different chemical species has been synthesized, and PET has been well-studied in liquid solutions. The extension of the principles of molecular sensors from liquid solution onto solid support is currently a major task, which opens up new directions for practical applications. An approach for the design of solid state fluorescence-sensing materials could be based on aggregation-induced emission (AIE). That is why, herein, we focused our attention on the investigation of some 1,8-naphthalimides designed on classical “fluorophore-spacer-receptor” to serve as fluorescence-sensing materials in solid state via simultaneous PET and AIE. The effects of different substituents were investigated, and it was found that the examined compounds with well-pronounced AIE could be used as an efficient platform for rapid detection of pH and acid/base vapors in solid state.

This review delves into recent advancements in the field of nitro(het)aromatic bioreductive agents tailored for hypoxic environments. These compounds are designed to exploit the low-oxygen conditions typically found in solid tumors, making them promising candidates for targeted cancer therapies. Initially, this review focused on their role as gene-directed enzyme prodrugs, which are inert until activated by specific enzymes within tumor cells. Upon activation, these prodrugs undergo chemical transformations that convert them into potent cytotoxic agents, selectively targeting cancerous tissue while sparing healthy cells. Additionally, this review discusses recent developments in prodrug conjugates containing nitro(het)aromatic moieties, designed to activate under low-oxygen conditions within tumors. This approach enhances their efficacy and specificity in cancer treatment. Furthermore, this review covers innovative research on using nitro(het)aromatic compounds as fluorescent probes for imaging hypoxic tumors. These probes enable non-invasive visualization of low-oxygen regions within tumors, providing valuable insights for the diagnosis, treatment planning, and monitoring of therapeutic responses. We hope this review will inspire researchers to design and synthesize improved compounds for selective cancer treatment and early diagnostics.