Sensitive multicolor visual detection of telomerase activity based on catalytic hairpin assembly and etching of Au nanorods

Detection of telomerase activity is crucial for the telomerase-related early diagnosis of cancer and drug screening. Herein, a multicolor visual telomerase detection method with high sensitivity was developed based on the etching of hexadecyl trimethyl ammonium bromide-stablized Au nanorods (Au NRs) by the oxidation state 3,3',5,5'-tetramethylbenzidine sulfate (TMB2+). In order to meet the demand of bare-eye inspection, an enzyme free signal amplification strategy of catalytic hairpin assembly (CHA) was incorporated. After the introduction of telomerase, telomerase extension products specifically triggered cyclic CHA and led to the successive formation of G-quadruplex/hemin DNAzyme, which catalyzed the H2O2-mediated oxidation of TMB. The Au NRs were gradually etched as the concentration of catalysate TMB2+ increased, resulting in the decrease of aspect ratio of the Au NRs. Correspondingly, the longitudinal localized surface plasmon resonance peak of Au NRs was blue shifted, with the concomitant generation of a series of color transition. Under optimal conditions, a highly sensitive detection toward telomerase was realized down to 15 HeLa cells. Compared to previous colorimetric method for telomerase determination, multiple colors corresponding to telomerase activity was the most attractive virtue of our approach. More strikingly, telomerase-induced cyclic CHA significantly enhanced the accumulation of G-quadruplex/hemin DNAzyme, thus the signal amplification was effectively realized. Our approach exhibited excellent sensitivity and convenient signal readout, which is expected to provide great potential application in cancer diagnosis and therapy.