Traditionally, visible fluorophores have been used as labels in DNA sequencing. They absorb and fluoresce in a region of the spectrum that is susceptible to biological interferences in sequencing samples. The increased noise level due to autofluorescence of glass, solvent, or impurities can greatly reduce the potential sensitivity of the analysis. In an attempt to increase the sensitivity, we have investigated the use of near-infrared (near-IR) fluorophores as labels in DNA sequencing. Near-IR fluorophores possess spectral properties which are observed between 700 and 1200 nm, a region with characteristically little interference by biomolecules. Therefore, the detection of near-IR dyes is not limited by noise levels, but rather by detector capabilities. Near-IR dyes are also suitable for selective excitation with commercially available laser diodes which can further enhance the observed fluorescence signal. We have covalently linked functionalized near-IR dyes to modified DNA oligomers for use in DNA sequencing. We report the synthesis and chromatographic purification of near-IR-labeled DNA oligomers. We further discuss the inherent properties of the conjugates and their use in DNA sequencing procedures.Fluorescent labels are being used increasingly in bioanalytical applications.1-6 They have been attached successfully to a variety of biomolecules such as enzymes, antibodies, and nucleic acids for use in immunoassay, flow cytometry, and sequencing

The binding of five near-infrared (near-IR) dyes to bovine serum albumin (BSA) has been evaluated by absorption, fluorescence, and circular dichroism. These dyes have a common squarilic acid polymethine backbone but differ in the substituents on two sites, R1 and R2, symmetrically located on the chromophore. The magnitude of the association constants for the dye–albumin complexes depended on the nature of the side chains and ranged from 34,000 to 1 × 107 M−1. Listed by the kind of side chain and in increasing binding order, the association constants are: [R1 = R2 = butyl phthalimide] < [R1 = R2 = cetyl] < [R1 = R2 = ethyl] < [R1 = butyl phthalimide, R2 = butyl sulfonate] < [R1 = R2 = butyl sulfonate]. The chromophore seems to interact mainly with a hydrophobic cavity on BSA. However, the association constants increase substantially when the side chain or chains are butyl sulfonate. This observation suggests that near the hydrophobic region there is at least one positively charged site with which the butyl sulfonate chain or chains interact. The molar ratio of the dye–albumin complex determined was 1:1. The optical constants of the dye–albumin complexes cannot be determined directly; therefore, a method is described for determining these complexes' optical parameters and thus their association constants.

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The spectroscopic characteristics in methanol of tetra substituted aluminum 2 , s napthalocyanines (2,3-NcAI) derivatives have been investigated. The tetrasubstitution of an aluminum naphthalocyanine molecule produces a bathochromic shift of the Q and B band. The N band showed almost no effect by the presence of the functional group and remained at a constant frequency; however, multiple overlapping of bands occurred between 25000 cm-' (400 nm) and 35000 cm-' (250 nm). The degree of bathochromic shift of the Q band was affected by the electron withdrawing or electron donating property of the substituents. Changes in the absorption of the Q, B and N band will be discussed.The fluorescence, quantum yield and molar absorptivity of the Q-band due to structural modifications are reported. The molar absorptivity ( E ) of the dyes was in the order of 3.5 (log E); however, higher E values were obtained with sulphonic groups. Solubility of these compounds in various solvents will be discussed. Possible use of the dye to determine metals and to other cations concentrations will be discussed.