Adenosine-aptamer recognition-induced assembly of gold nanorods and a highly sensitive plasmon resonance coupling assay of adenosine in the brain of model SD rat.

In this contribution, we report a molecular recognition between adenosine and its aptamer, which leads to the formation of a four-stranded tetraplex structures (G-quartet) of the aptamer. It is found that the formed G-quartet could induce the side-by-side self-assembly of gold nanorods (AuNRs) owing to the electrostatic interaction between the positive charge of cetyltrimethylammonium bromide (CTAB) on the AuNR surface and the negative charge of the formed G-quartet. Furthermore, the side-by-side self-assembly of AuNRs is characterized by the enhancement of plasmon resonance light scattering (PRLS) signals and the blue-shift of the longitudinal plasmon resonance absorption (LPRA) band owing to the plasmon resonance coupling. Then, based on the enhanced PRLS signals, a simple, highly selective and sensitive detection method for adenosine was developed in the range of 4.0-80.0 nM with the limit of determination of 2.0 nM, which is up to now the best sensitive optical detection method to our knowledge. This method has been successfully applied to the detection of adenosine phosphates in the brains of SD rats, which was in good agreement with a high-performance liquid chromatographic (HPLC) method.