This proposed research is categorized under preventive medicine (new diagnostic tests). The broad purpose of this project is to synthesize new boron-based dyes, investigate their photochemical and cellular properties for potential applications in fluorescence labelling and in bioimaging. The new dyes are expected to complement known BODIPYs (boron-dipyrromethenes) fluorophores which have been studied extensively, but absorb only in the visible region of the spectrum. The new proposed dyes are expected to absorb at UV-Vis, far-red or near-IR wavelengths which is an attractive property for deep tissue imaging since light penetration through body tissue is known to increase with increased wavelength. In vivo fluorescence helps the physician to avoid unnecessary cuts during surgery. The proposed aryl fused dimers are expected to display red-shifted absorptions and emissions and enhanced fluorescence compared with BODIPY dyes. Readily available synthetic materials and laser probes will be used in this investigation. To enhance cellular uptake, tumor cell selectivity, and controlled cellular retention, the PI will meticulously choose the "R" group and substitute the boron center to functionalize the proposed dye with water-solubilizing PEG, sugars, sulfonic acid, quaternarium ammonium groups, or amino acids. Some of these would be synthesized in the second phase of the project depending on primary cell studies results using human HEp2 cells.