Fluorescent Probes as a Tool in Diagnostic and Drug Delivery Systems

Abstract

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.

Preferential Binding of a Red Emissive Julolidine Derivative to a Promoter G‐Quadruplex

“…Fluorescent DNA binding molecules have found numerous uses as diagnostic agents [48] both within cells and in the development of new biosensors for varied uses including ion sensing. [49,50] Some of the nucleic acid binding fluorescent molecules are Thioflavin T, [51] Hoechst 33342, [52] DCVJ, [43] and HJVPI, [53] which are known to have applications beyond nucleic acid recognition as molecular rotors to detect G-bulges, cell, and gel staining agents to name few.…”

Rigidify styryl-pyridinium dyes to benzo[h]coumarin-based bright two-photon fluorescent probes for cellular bioimaging

“…9,10 Many important low-molecular-weight organic fluorescent probes have been developed and commercialized. 11 For example, fluorescent probes have been used to identify cancer-related markers, observe the interactions and dynamic changes between organelles in real time, and detect changes in the cell microenvironment (such as polarity, viscosity, and pH). 12–15…”

Design and Screening of Fluorescent Probes Based upon Hemicyanine Dyes for Monitoring Mitochondrial Viscosity in Living Cells

“…In contrast, the fluorescence technology is a powerful tool for biological applications due to its simple operation, good spatial and resolution, and excellent sensitivity. 3,4 Fluorescent dyes with high sensitivity to environmental changes, such as molecular rotors, are widely used for viscosity monitoring in biological structures. 5,6 Molecular rotors are fluorescent molecules with the intramolecular charge transfer (ICT) mechanism that undergo twisting motion in the excited state.…”

“…However, traditional viscosity measurement methods are not suitable for applications in cells or living organisms. In contrast, the fluorescence technology is a powerful tool for biological applications due to its simple operation, good spatial and resolution, and excellent sensitivity. , …”