Investigators require noninvasive extrinsic probes to obtain key information about abnormalities in cellular function and biomolecular interactions. Metal nanoclusters made of Ag are likely to prove highly effective in this regard, due to their strong fluorescence and high stability. DNA oligonucleotides serve as templates to grow metal nanoclusters which are highly emissive and stable, allowing them to be used as noninvasive biological labels for in vivo interrogation. Near infrared (NIR) emissive and highly stable bio-probes are important in advancing studies of individual biomolecular function. Successful transfection of these NIR probes inside live human cells through appropriate amphiphilic vectors will open the door to a new paradigm of biomedical imaging in disease diagnosis. Through the careful selection of nucleotide sequences, we plan to synthesize a new class of near-infrared (NIR) fluorescent clusters that can be used for in vivo interrogation. Improved photon penetration through tissues by NIR longer wavelength (above 700 nm) reduces background fluorescence of live cells as well as provide detail anatomic and molecular information, making the NIR emissive silver nanoclusters ideal as novel biological probes.. We initiated our studies using single stranded DNA oligonucleotides with varied sequences where each has an abundance of a specific DNA base (adenine, gunanine, thymine and cytosine). UV/Vis absorption and fluorescence spectroscopic investigations were carried out and preliminary results indicate a specific sequence to have more NIR emission than the other. Specific emission and absorption bands are characteristics of a particular DNA oligonucleotide. Highly parallel analysis will be conducted using systematic variations in sequences of short oligonucleotides from an array. The effect of unusual DNA structures on the formation of the NIR emitting species will be studied. Screening will be performed to identify stable NIR fluorescent silver nanocluster in physiologically compatible environments.

DNA scaffolded NIR emissive silver nanoclusters

248th National Meeting (2014)

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