Aptamer single-molecule dispersion on single-atom anchoring sites for high-selectivity <i>in vivo</i> detection

Traditional aptasensors struggle to distinguish molecules with highly similar chemical structures due to the inherent flexibility of aptamers, which form 'nano-bushes' causing non-specific adsorption and reducing sensor specificity. To address this, we propose a novel strategy of anchoring aptamers at the single-molecule level onto atomic anchoring sites. We have designed a gold single-atom/titanium dioxide (Au SA/TiO₂) photoelectrode to immobilize a dopamine (DA)-selective aptamer, enabling the fabrication of a photoelectrochemical single-molecule aptamer sensor (PEC-sm-aptasensor). This sensor can selectively detect DA <i>in vivo</i> in different brain regions of living mice. This advancement has revolutionized our understanding of DA variation in the prefrontal cortex of Parkinson's disease (PD) mice. In contrast to previous beliefs, we have discovered a new neurotransmitter dynamic pattern: while the total concentration of neurotransmitters decreases, the concentration of DA remains constant, thus not affecting cognitive levels. This finding is crucial for a more targeted understanding of PD and opens avenues for more effective treatments and diagnostic methods.