First principles study of the optical response of Au8 cluster conjugated with methionine, tryptophan, and tryptophyl-methionine dipeptide

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Department of Physics


Bioconjugated complexes of the Au clusters are shown to demonstrate unique electronic properties and exceptional tunable optical features for applications in health-related areas including cell imaging and target-specific drug delivery. To establish the relationship between the optical response and the nature of interaction in such complexes, we consider the cases of the representative amino acids, L-methionine, L-tryptophan, and L-tryptophyl-L-methionine dipeptide conjugated with Au cluster. The results based on time-dependent density functional theory find the near-ultraviolet (UV) absorption of the complexes is dominated by the cluster, though site-specific interactions through the indole chromophore or thioether side chains provide their signature responses in the optical spectra. Under physiological conditions, the predicted optical recognition of specific bonds formed between Au cluster and amino acids can then be exploited in the design of functional fluorescent bio-labels for biochemical sensing and detection of thiols, polypeptides, proteins, and nucleic acids at nanoscale.

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Journal of Physical Organic Chemistry