1602 wileyonlinelibrary.com biological environments. Recently, a telomerase-responsive off/on fl uorescent probe was prepared using a DNA-based biogate on mesoporous silica nanoparticles (NPs). [ 15 ] Molecular beacons, [ 16 ] such as the nicked-molecular-beacon-functionalized probe, [ 17 ] have also been fabricated to detect intracellular telomerase activity, and electrochemical techniques [ 18 ] and primer-modifi ed NP-based methods [ 19,20 ] have been used to quantify the telomerase activity in cell lysates. However, their limited sensitivity and applicability in complex matrices remain a signifi cant problem.Surface-enhanced Raman scattering (SERS), a promising technique for chemical and biological sensing, [ 21 ] provides spectral fi ngerprint signatures of analytes, which endow SERS sensors with a better resistance to interference by non-specifi c molecules. [22][23][24][25][26][27][28][29][30][31][32][33][34] NPs have been employed to assist in genotyping [ 35 ] or used as a substrate upon which the fi ngerprint spectra of the target were obtained. [ 36 ] However, the main drawback of encoded single NPs is their weak SERS signals. Signifi cant progress has been made in the synthesis of controllable NP assemblies [37][38][39][40][41][42][43][44][45][46][47][48][49][50] and we believe that there is no limit to the bioanalytical applications of these nanoassemblies.Recently, our group has developed a silver (Ag) pyramid that adjusts the interparticle distance before/after aptamertarget molecule recognition to simultaneously detect prostatespecifi c antigen, mucin-1, and thrombin at the attomolar level in a buffer solution. [ 51 ] Despite this progress, new strategies are needed to achieve a stable geometrical arrangement of the nanoparticles and an evenly spread effective area in the pyramids to rule out SERS signal fl uctuations. However, to the best of our knowledge, the detection of intracellular telomerase using a nanoparticle assembly-based SERS method has not been reported thus far. Further research is required to address these challenges, especially the development of sensors for the ultrasensitive detection of telomerase in living cells.In this study, we fabricated a pyramid, designated the "Py-SERS probe", using Cy5 as the SERS reporter. The overall strategy is shown in Figure 1 . Briefl y, DNA frames embedded with telomerase primer were used to prepare gold nanoparticle (Au NP) pyramids, in which four single-stranded DNA The highly sensitive and quantitative biodetection of intracellular telomerase is challenging. A DNA-driven nanoparticle self-assembling pyramid encoding a Raman reporter (Cy5) is reported that detects telomerase in live cells. In the presence of the target, the telomerase primer is extended and the inner DNA chain is replaced, leading to the reduction in the surface-enhanced Raman scattering (SERS) signal and the simultaneous recovery of the fl uorescent signal. The SERS signal has a linear range for the detection of telomerase in situ of 1 × 10 -14 to 5 × 10 -11 IU, with a limit o...
