Executive Summary : | Organic dye-based fluorescent probes are popular tools for real-time, on-site, and non-invasive visualization of environmentally and biologically important molecules due to their advantages such as good brightness, biocompatibility, excellent photostability, and flexibility in synthesis and functionalization. The emerging class of fluorogens with aggregation induced emission characteristics (AIEgens) are attracting attention in the design and synthesis of light-up organic materials for sensing these molecules. AIE fluorogens can be engineered to show extremely weak fluorescence in aqueous media by endowing them with water solubility, making them compatible with biological systems. Far-red, near-infrared (FR or NIR) responsive organic materials with longer absorption and emission wavelengths are attractive for bioimaging with a deeper penetration depth. This project focuses on designing advanced FR, NIR AIEgen-based light-up organic materials with desirable functionalities for highly selective and sensitive toward various important analytes in biological and environmental samples. The design and synthesis of NIR fluorescent AIE-active organic materials consider several design factors, such as conjugation length, bond length alternation, and donor-pi-acceptor charge transfer. Specific AIE light-up probes operate through direct binding with a specific target or site-specific reaction due to the presence of the target analyte, which is highly desirable for biomarker detection and sensing enzymes or other molecules that undergo cleavage reactions with the probe. |