ABSTRACT
The DNA-enabled dimerization of pentamethine cyanine (Cy5) dyes was studied by optical methods. The value of cyanine as a chiroptical reporter using a monomer-to-dimer switch is demonstrated. The specific shape of the CD signal and its high intensity are a result of J-type assembly.
Subject(s)
Carbocyanines/chemistry , DNA/chemistry , Fluorescent Dyes/chemistry , Circular Dichroism , Dimerization , Nucleic Acid Conformation , Spectrometry, FluorescenceABSTRACT
The incorporation of squaraines into DNA via the phosphoramidite approach is described. High molar absorptivity, environment-sensitive fluorescence properties and intense CD effects render squaraines valuable building blocks for DNA-based optical probes and nanostructures.
Subject(s)
Cyclobutanes/chemistry , DNA/chemistry , DNA/chemical synthesis , Phenols/chemistry , Chemistry Techniques, Synthetic , Oligodeoxyribonucleotides/chemical synthesis , Oligodeoxyribonucleotides/chemistry , Optical Phenomena , Organophosphorus Compounds/chemistry , Spectrum AnalysisABSTRACT
We describe the spectral properties of an amine-reactive, pH-sensitive, long-wavelength ratiometric fluorescent label having a pK(a) in the physiological pH range. The label exhibits its main absorption and emission in the near-infrared (NIR) region. On deprotonation, a blue shift of the excitation maximum is observed. Importantly, both the protonated and deprotonated forms of the label are fluorescent, with the deprotonated form having an extremely large Stokes shift of more than 100 nm. The spectral and photophysical properties of this pH label are compared with the properties of the protein-conjugated forms. Due to the observed pK(a) shift to the acidic pH range upon conjugation to proteins, such labels are ideal for studying phagocytic events and their regulation by drugs and/or environmental factors.
