A ratiometric SERS aptasensor array for human DNA glycosylaseat single-cell sensitivity/resolution

Human 8-oxoguanine DNA glycosylase (hOGG1) is involved in the cellular genomic 8-oxoguanine (8-oxoG) excision repair to maintain genome stability. Accurate detection of hOGG1 activity is essential for clinical diagnosis and treatment of various human pathology. Yet, the quantitative detection of hOGG1 remains challenging for existing methods due to poor reproducibility and portability. Herein, we propose a ratiometric arraybased SERS point-of-care testing method for hOGG1 activity. A kind of reproducible, uniform and stable plasmonic multi-microarray reaction cells was constructed by assembling AuNPs on the substrate modified by aminosilane and segmented by silica gel gasket, which greatly improved the sensitivity, portability and repeatability of SERS measurement. Based on this, the ratiometric method is further used to effectively overcome the instability of single SERS signal intensity, which allows signal rationing and provides built-in correction for environment effects. In specific, we designed two different Raman-labeled probes for the detection of hOGG1, a thiol- and Cy3-labeled aptamer as an internal standard and a Rox-labeled 8-oxoG-modified complementary aptamer as a signal probe. The ratio value between Cy3 and Rox SERS intensity is well linear with the hOGG1 activity on logarithmic scales in the range from 5 x 10-5 to 5 x 10-3 U/mL, and the limit of detection reaches 3.3 x 10-5 U/mL. Moreover, this strategy can be applied for the screening of inhibitors and the monitoring of cellular hOGG1 activity fluctuation at single-cell levels, providing a flexible and adaptive tool for clinical diagnosis, biochemical processes and drug discovery.