Telomerase Detection Research Articles

“Black body” effect of carbon nanospheres: A broadband energy acceptor in constructing electrochemiluminescence resonance energy transfer for biosensing

Abstract Electrochemiluminescence resonance energy transfer (ECL-RET) is a powerful analytical strategy based on the resonance energy transfer (RET) between an efficient electrochemiluminescence (ECL) emitter and an especially matched energy acceptor. However, finding a suitable energy acceptor with good stability and efficiency energy absorption capability is still challenging. In this study, an ECL-RET biosensing system was designed by using the “black body” effect of carbon nanospheres (CNSs). For the energy donor, an ECL amplification system consisting of ZnO nanorods (NRs) coating with CdS nanocrystals (NCs) was used to demonstrate the principle. Telomerase was used as a model sensing target, and the telomerase-triggered elongation of template strand (TS) primer was carried out, followed by the hybridization with the complementary strand (cDNA) on the surface of CNSs surface, effectively resulting in the ECL quenching. The ECL-RET sensing approach endows a sensitive detection limit of 1 cell with a signal linearity in the ranges 2–10 cells and 10–10,000 cells. This ECL sensing platform also exhibits a high performance in telomerase detection in urine specimens. Overall, the broad absorption feature of carbon materials might provide a universal and effective candidate as energy acceptor in constructing sensitive ECL-RET system for developing sensitive, rapid, and accurate biological detection platform.

A Highly Sensitive Catalytic Hairpin Assembly-Based Dynamic Light-Scattering Biosensors for Telomerase Detection in Bladder Cancer Diagnosis.

Precise evaluation of telomerase activity is highly crucial for early cancer diagnosis. In this study, a sensitive catalytic hairpin assembly-dynamic light scattering (CHA-DLS) assay for telomerase activity detection is developed by using the diameter change of gold nanoparticle (AuNP) probes. The telomerase substrate primer can be extended in the presence of telomerase, producing a telomerase extension product (TEP) with telomeric repeat units (TTAGGG)n at its 3'-end. The TEP can specifically trigger the CHA process and form tremendous AuNPs-H1/H2 nanostructures, resulting in a significant increase in the diameter measured by DLS. Telomerase activity from different cancer cell lines (MCF-7, Huh7, and 5637) was detected using the proposed strategy, the diameter of AuNP probes increased with the number of cancer cells, and this method can accurately detect telomerase activity down to 6 MCF-7 cells, 10 Huh7 cells, and three 5637 cells. Moreover, the CHA-DLS biosensor was successfully applied in urine specimens from healthy individuals and different cancer patients, which can distinguish bladder cancer patients from healthy people and other cancer patients, indicating that the noninvasive method has a great potential for application in early diagnosis of bladder cancer.

Target-Driven Nanozyme Growth in TiO2 Nanochannels for Improving Selectivity in Electrochemical Biosensing.

Nanozymes have been used in colorimetric and electrochemical sensing because of their low cost and high stability. However, the wide applications of nanozymes in sensing devices are largely limited due to their poor selectivity. In this study, unlike traditional methods using prepared nanozymes for target detection, we designed a target-driven nanozyme growth strategy in TiO2 nanochannels to detect analytes. Using telomerase as an example, the established recognition event was used to expand the photocatalytic activity of TiO2 to visible-light region, thus triggering Prussian blue nanoparticle (PBNP) growth in visible light. Benefiting from the peroxidase (POD)-like activity of PBNPs, the uncharged 3,5,3',5'-tetramethylbenzidine (TMB) is oxidized to positively charged oxTMB, which induces significant ionic transport changes in nanochannels, and thus in turn provides information about telomerase activity. Such a nanozyme-triggered sensing system exhibited excellent performance in telomerase detection in urine specimens from patients with bladder cancer. This innovative target-driven signal generation strategy might provide a new method for applying nanozymes in developing sensitive, rapid, and accurate biological sensing systems.

Magnetic bead-enzyme assemble for triple-parameter telomerase detection at single-cell level.

In this work, we developed a triple-parameter strategy for the detection of telomerase activity from cancer cells and urine samples. This strategy was developed based on magnetic bead-enzyme hybrids combined with fluorescence analysis, colorimetric assay, or adenosine triphosphate (ATP) meter as readout. The application of magnetic bead-enzyme hybrids has the advantages of magnetic separation and signal amplification. These detection methods can be used individually or in combination to achieve the optimal sensing performance and make the results more convincing. Among them, the ATP meter with portable size had easy operation and low cost, and this response strategy provided a higher sensitivity at the single-cell level. The designed strategy was suitable as naked-eye sensor and point-of-care testing (POCT) for rapid assaying of telomerase activity. Graphical abstract Magnetic bead-enzyme assemble for triple-parameter telomerase detection.

Gelatin nanoparticles transport DNA probes for detection and imaging of telomerase and microRNA in living cells

Telomerase and microRNA (miRNA) are biomarkers closely related to tumors. Simultaneous detection of both markers can improve accuracy and reliability of early diagnosis. Based on the mechanism of fluorescence resonance energy transfer (FRET), two fluorescent DNA probes were designed for telomerase and miRNA-21. The probes were wrapped by gelatin through electrostatic interaction to form nanoparticles. After that, we synthesized molecularly imprinted coating of transferrin on the surface of gelatin nanoparticles, which can avoid the immune stress response and macrophage phagocytosis to help gelatin nanoparticles enter into the cells smoothly through endocytosis. Following with the degradation of gelatin in the cells, DNA probes were released to react with telomerase and miRNA-21 and lead to the change of the fluorescence signal. Thereby the simultaneous imaging of telomerase and miRNA-21 were successfully achieved in HeLa cells and HepG2 cells. The proposed strategy shows the simultaneous imaging for different biological markers with DNA probes by preventing them from being hydrolyzed with nucleases before the determination and achieves reliable method for early diagnosis of cancer.

Survivin and Telomerase as Radiotherapeutic Response Predictors of Subjects with Stage IIIB Cervical Squamous Cell Carcinoma

BACKGROUND: Cervical cancer is one of the most prevalent cancers in women. Even with similar clinicopathologic features, radiotherapy outcomes are still vary among patients. This research was conducted to measure radiotherapy responses on cervical cancer patients by using Survivin, Telomerase and Cytochrome C.METHODS: Subjects who matched the criteria were selected and requested to fill questionnaires. Subjects were then evaluated with magnetic resonance imaging (MRI) pre- and post-3D conformal radiotherapy. Histopathological study was conducted using resected tumors to determine the differentiation type. Enzyme-linked Immunosorbent Assays for detection of Survivin, Telomerase and Cytochrome C was performed using the resected tumors as well.RESULTS: There were 76 patients in this study. Mean ofage was 50 and diameter of tumor size was 5.35 cm. Mean levels of Survivin, Telomerase and Cytochrome C were 632.82 pg/mL, 5.59 pg/mL and 204.75 ng/mL, respectively. There were significant correlations between radiotherapy response and Survivin (p=0.041) or Telomerase (p=0.022). Subjects with lower Survivin level (<932 pg/mL) had higher 1-year survival rate (63%) than subjects with higher Survivin level (50%). Similar results were obtained for subjects with lower Telomerase level (<5.75 pg/mL), who had higher 1-year survival rate (60%) than subjects with higher Telomerase level (43%).CONCLUSION: Since radiotherapy response is significantly correlated with Survivin and Telomerase levels and subjects with lower Survivin or Telomerase level have higher 1-year survival rate, it can be suggested that Survivin and Telomerase could be potential predictors of radiotherapeutic response for subjects with stage IIIB cervical squamous cell carcinoma.KEYWORDS: cervical cancer, radiotherapy Survivin, Telomerase, Cytochrome C

Facile synthesis of fluorescent tungsten oxide quantum dots for telomerase detection based on the inner filter effect.

The traditional detection of telomerase activity is mainly based on the polymerase chain reaction (PCR), which has the disadvantages of being time-consuming and susceptible to interferences; thus, here, we propose a facile method for the fabrication of fluorescent tungsten oxide quantum dots (WOx QDs) and employ them for telomerase activity sensing. It is found that the fluorescence of WOx QDs can be significantly quenched by hemin based on the inner filter effect (IFE). However, in the presence of telomerase, the primer-DNA can be extended to generate repeating units of TTAGGG to form G-quadruplex and thus, hemin can be encapsulated to reduce its absorbance, resulting in decreased IFE and efficient fluorescence recovery of WOx QDs. Based on the fluorescence changes of IFE between hemin and WOx QDs, the telomerase activity within the range of 50-30 000 HeLa cells can be detected and the lowest detection amount can reach 17 cells. The method exhibits good versatility that can also be applied to telomerase detection in A549 and L929 cells. In addition, because of the good biocompatibility of the sensor, it can be used for the real-time monitoring of telomerase activity in living cells, thus showing great potential in tumor diagnosis and inhibitor drug screening.

Tetrahedron Probes for Ultrasensitive In Situ Detection of Telomerase and Surface Glycoprotein Activity in Living Cells.

In the present study, a tetrahedron probe with encoded internal reference nanoparticles (NPs) was self-assembled by a complementary nucleic acid aptamer for simultaneous ratiometric detection of telomerase (TE) and epithelial cell-adhesion molecule (EpCAM) in living cells. In the presence of a target, the dissociation of gold (Au) NPs, which was modified with corresponding tags, resulted in decreased surface-enhanced Raman scattering (SERS) signals. In addition, the ratios of Raman intensity at 1346 cm-1/1096 cm-1 (TE) and 1614 cm-1/1096 cm-1 (EpCAM) compared with the internal reference were demonstrated to quantify the level of TE and EpCAM, respectively, and can eliminate certain background noise. A good linear relationship was observed between them, and the linear range of TE and EpCAM in HeLa cells was 0.7 × 10-12 to 37.5 × 10-12 IU and 1.24 to 75.48 pg/mL with a limit of detection (LOD) of 7.6 × 10-16 IU and 0.53 pg/mL, respectively, which were consistent with the results of Raman confocal imaging. Meanwhile, the versatility and specificity of the developed probes were confirmed in cell lines. These results provide a reliable and ultrasensitive strategy for the in situ detection of biomarkers and a new method for SERS-based tetrahedrons in the early diagnosis of cancer.

Sensitive detection of telomerase activity in cells using a DNA-based fluorescence resonance energy transfer nanoprobe

Telomerase activity is inhibited in normal somatic cells but abnormally high in the majority of cancer cells. Maintenance of active telomerase in cancer cells promotes proliferation and immortalization. With the difference in telomerase activity between cancer and normal cells in mind, we designed a nanoprobe based on quantum dot (QD) and fluorescence resonance energy transfer (FRET). The nanoprobe consisted of a specific sequence of DNA with the two ends labeled with QD as a fluorescent donor and Alexa488 as a fluorescent acceptor, respectively. FRET signal tracking was performed by adjusting the distance between donors and acceptors, and changes in the FRET signal shown to be related to telomerase activity. Incubation of cells with the nanoprobe facilitated sensing of intracellular telomerase activity, and consequent discrimination between normal and cancer cells. Our novel DNA nanoprobe based on QD-FRET achieved sensitive detection of telomerase in cells up to a detection limit of one cell, and quantitative detection of telomerase activity in different numbers of cells. The nanoprobe generated in this study is expected to allow dynamically monitoring of the changes in telomerase activity in cells under treatment with drugs, providing a potential basis for early diagnosis and management of cancer.

Regulation of multiple energy transfer processes in a simple nano-system for sensitive telomerase detection

Telomerase, as a potential biomarker for early cancer diagnostics and therapies, has attracted considerable interests concerning its detection and monitoring. Herein, we develop a novel method for sensitive detection of telomerase activity by designing a gold nanoparticles/graphene oxide (AuNPs/GO) probe. The AuNPs were functionalized with a telomerase substrate (TS) primer and a 6-carboxy-fluorescein (FAM)-modified complementary DNA (P1). In the absence of telomerase, P1 exists in the random-coiled conformation, and the fluorescence resonance energy transfer (FRET) from FAM to AuNPs and GO results in efficient fluorescence quenching. In the presence of telomerase, the multiple hybridization between TS extension products and P1 leads to the conformation transition of P1 from single-stranded DNA to double-stranded rigid structure, and thus the FRET process can be prevented with the efficient fluorescence recovery. The metal enhanced fluorescence (MEF) effect between FAM and AuNPs can further effectively enhance the fluorescence of FAM, and thus the sensitivity and specificity of telomerase detection can be remarkably improved. It is worth mentioning that the proposed strategy does not need to design complex hairpin structure and allows the measurement of telomerase activity in three crude cell extracts equivalent to 7 HeLa cells, 8 A549 cells and 8 L929 cells in 1 h. In addition, the present sensing platform can be applied to inhibitor screening, in situ telomerase imaging, and intracellular drug delivery.

Monitoring Telomerase Activity in Living Cells with High Sensitivity Using Cascade Amplification Reaction-Based Nanoprobe.

Human telomerase has been considered as a promising tumor marker for early cancer diagnosis and tumor progression monitoring. Current methods for detection of telomerase mainly rely on in vitro assays using cell lysate, which cannot provide information on telomerase activities in living systems. Only the few reported intracellular probes possess high telomerase selectivity but involve no signal amplification process, which potentially limits their use in application scenarios requiring high sensitivity. The development of an ultrasensitive intracellular telomerase probe is of high demand but challenging, because of the difficulty in designing a robust amplification process in living cells. Inspired by the mechanism of telomerase primer binding and extension, we introduce a cascade amplification reaction-based nanoprobe for intracellular telomerase detection by incorporating DNAzyme and catalytic hairpin assembly onto MnO2 nanosheets. The MnO2 nanosheets can deliver and release multicomponent signal amplification motifs with designed ratio at the same intracellular position, thereby enabling the cascade process in cells to occur. The released Mn2+ ions from degraded MnO2 nanosheets can activate DNAzyme as a metal cofactor and facilitate endosomal escape, because of the ion sponge effect. We used the nanoprobe to successfully monitor the dynamic change of telomerase activity in the HeLa cell, as well as in three other types of cells. This cascade amplification nanoprobe provides ultrasensitive detection of telomerase activity, indicating its use as a promising bioassay for early cancer diagnosis.

Telomerase-triggered DNAzyme spiders for exponential amplified assay of cancer cells

A highly flexible electrochemical assay based on target-triggered DNAzyme spiders was proposed for the detection of telomerase. The DNAzyme-telomerase substrate primers (D-TSP) containing Cu2+-dependent DNAzymes serve as recognition elements, and primers of telomerase. Telomerase extracted from Hela cells recognize the D-TSP and elongated with DNA sequence repeats. A synthetic telomerase product hybridized with scaffold sequences of two DNAzyme-tethered probes on the basis of the mechanism of the proximity-ligation assay. The three-leg DNAzyme spiders has been assembled and initiated the autonomous hybridization/nicking/displacement cycles on substrate modified surface. The cleaved ferrocene-labeled fragements are adsorbed on gold surface leading to an increase in the electrochemical signal. As a result, the one input target, telomerase, release large amount of ferrocene-labeled DNA strands, achieving an exponential signal amplification and an excellent improvement in sensitivity over single molecule or two-component ‘sandwich’ binding complexes. Our proposed biosensor showed a nonlinear dependence with Hela cell numbers, ranging from 25 to 2000 with a detection limit of 10 cells. Telomerase activities from different cell lines were also successfully evaluated. Our electrochemical strategy based on target-triggered DNAzyme spiders was enzyme-free, PCR-free, simple in operation which indicated that it expected to expand the scope of DNA nanotechnology in the areas of clinical diagnosis.

A multi-recycling amplification-based sensor for label-free and highly sensitive detection of telomerase from cancer cells

The development of methods that can detect telomerase with high selectivity and sensitivity is critical for early diagnosis and treatment of telomerase-related cancers. In this regard, we describe in this work the establishment of a telomerase-initiated and nicking endonuclease-assisted cascade recycling signal amplification approach for non-label and highly sensitive fluorescent detection of telomerase from cancer cells. The target telomerase triggers the elongation of one strand in a partial dsDNA duplex with a pre-designed sequence to induce the release of a ssDNA, which can initiate three cascaded recycling cycles for the generation of many G-quadruplex sequences by cleaving two hairpin signal probes with the assistance of the Nt.AlwI endonuclease. The thioflavin dye further binds these G-quadruplex sequences to exhibit substantial fluorescence enhancement for sensitive detection of telomerase at 8.93 × 10−11 IU. Moreover, this developed method is capable of differentiating telomerase activity among different cancer cells and screening telomerase inhibitors for anticancer drugs.

Telomerase Triggered DNA Walker with a Superhairpin Structure for Human Telomerase Activity Sensing.

Different from conventional DNA walkers, we designed a telomerase-triggered three-dimensional DNA walker consisting of a superhairpin structure with a bulged loop in the stem as the walking strand and dye-labeled tracks for ultrasensitive detection of telomerase activity. In the presence of telomerase, the primers in the stem of the superhairpin structure were elongated and triggered internal strand displacement, thus activating the superhairpin structure. Subsequently, the open superhairpin structure as a swing arm was able to bind with the track, and the swing arm could be released by enzymatic cleavage of the binding duplex domain, resulting in the fluorescence recovery of dye-labeled fragments from the surface of gold nanoparticles. Based on signal amplification of the telomerase-triggered DNA walker, the walking device was further applied to various cancer lines with a low detection limit of telomerase activity equivalent to 90 cells μL-1 for HeLa cells. Moreover, the advantage of this DNA walker strategy was confirmed by calculating telomerase activity in a single cell. This telomerase-triggered DNA walker provides a new concept on signal transduction for telomerase detection and is anticipated to stimulate interest in DNA nanomachine design for bioanalysis.

Electrocatalysis of cerium metal-organic frameworks for ratiometric electrochemical detection of telomerase activity

A ratiometric electrochemical biosensor was constructed to detect telomerase activity based on electrocatalysis of cerium-based metal-organic frameworks (CeMOFs) and conformation switch of hairpin DNA. First, the CeMOFs were synthesized using Ce as nodes and 1,3,5-benzenetricarboxylic acid as linker in a green method, and then functionalized with gold nanoparticles. The resulted Au@CeMOF tags demonstrated an excellent electrocatalysis toward hydroquinone oxidation. Meanwhile, a methylene blue (MB) modified hairpin probe was designed with telomerase primer (TP) hybridized “stem” and immobilized on the electrode surface via Au–S chemistry. In the presence of the dNTPs and telomerase, the extended TP can open the hairpin DNA and keep the MB away from the electrode surface, resulting in a decrease of electrochemical signal. In the meantime, the TP-extended part could capture the Au@CeMOF-cDNA tags on the electrode surface via hybridization, leading to the increase electrochemical signal of hydroquinone oxidation catalyzed by Au@CeMOF-cDNA tags. Thus, a ratiometric signal output mode was developed for the electrochemical detection of telomerase activity. This biosensor showed wide dynamic correlation of telomerase activity from 2 × 102 to 2 × 106 cells mL−1 with the limit of detection of 27 cells mL−1, and was applied to evaluate telomerase activity in single cell. The ratiometric electrochemical strategy based on the catalysis of MOFs provides a new avenue on signal transduction in telomerase detection.

Highly sensitive fluorescence biosensor for intracellular telomerase detection based on a single patchy gold/carbon nanosphere via the combination of nanoflare and hybridization chain reaction

How to in situ detect intracellular telomerase activity with high sensitivity still faces many challenges. This paper constructs a new fluorescence biosensing platform for the sensitive detection of intracellular telomerase activity via the combination of nanoflare and hybridization chain reaction (HCR)-based signal amplification on a single patchy gold/carbon nanosphere (PG/CNS), which has two or more distinct parts and allows hybridized-DNA (HS-DNA/Primer-DNA/Flare-DNA) and H1/H2-DNA (a pair of cross complementary DNA hairpins) to bind onto their surfaces via Au–S bond and electrostatic interaction, respectively. In the presence of telomerase, Primer-DNA (telomerase primer) extends at its 3′ end to produce a telomeric repeated sequence, resulting in the release of Flare-DNA followed by the recovery of the fluorescence. Subsequently, the released Flare-DNA further initiates cross hybridization of H1 and H2 DNA from mimic-HCR system to amplify the fluorescence signal. The in vivo confocal microscopy studies demonstrate that resulting sensor can enter into the cancer cells such as A549 cells, and lead to the increase in luminescence, which is stronger than the sensor without the HCR-based signal amplification system. A linear relationship between the fluorescence intensity and the amount of A549 cells is observed, and the limit of detection of the sensor reaches about 280 A549 cells.

Cobalt phosphide nanowires for fluorometric detection and in-situ imaging of telomerase activity via hybridization chain reactions.

The authors describe cobalt phosphide (CoP) nanowires for use in sensitive fluorometric determination of the activity of the enzyme telomerase. A hybridization chain reaction (HCR) is applied to amplify the signal and carboxyfluorescein (FAM)-labelled hairpin probes (H1 and H2) are applied to match the telomeric DNA sequence. The CoP nanowires act as both the photoinduced electron transfer (PET) acceptor to induce fluorescence quenching, and also as an efficient probe carrier to facilitate telomerase imaging in living cells. The telomerase-triggered primer extension initiates an alternating hybridization reaction between H1 and H2. These result in the dissociation of FAM-labelled probes from CoP nanowires and thus an enhancement of the green fluorescence. The method is fairly simple and was applied to the detection of three types of cancer cells. The detection limit is as low as 7 cells (in case of HeLa cells). Conceivably, the method has a large potential in terms of inhibitor drug screening. Graphical abstract Schematic presentation of telomerase detection based on cobalt phosphide (CoP) nanowires and hybridization chain reaction (HCR). The telomerase-triggered primer extension can initiate the alternating hybridization reaction between carboxyfluorescein (FAM)-labelled hairpin probes (H1 and H2), and the generated long DNA duplex cannot be adsorbed on theCoP nanowires. This prevents the photoinduced electron transfer (PET) from FAM to CoP nanowires.

Diagnostic value of detection of peripheral blood human telomerase reverse transcriptase mRNA and four tumor markers in patients with gastric cancer

Objective To evaluation the value of single and combined detection of peripheral blood human telomerase reverse transcriptase (hTERT) mRNA and tumor markers carcinoembryonic antigen (CEA), carbohydrate antigen 72-4 (CA72-4), CA19-9 and CA125 in the diagnosis of gastric cancer. Methods A total of 48 patients diagnosed with gastric cancer from June 2017 to October 2018 in Baotou Tumor Hospital were enrolled in the study group. Fifty healthy subjects were selected as healthy control group. The peripheral venous blood samples were collected from all subjects. After the synthesis of hTERT cDNA by reverse transcription, real-time fluorescence quantitative polymerase chain reaction (RT-PCR) was used for the amplification of hTERT gene fragment. The tumor markers CEA, CA72-4, CA19-9 and CA125 were quantitatively detected by electrochemiluminescence instrument. The sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio and negative likelihood ratio of individual markers or joint detection were calculated. The sensitivity and specificity of joint testing items were compared. Results There were statistically significant differences in the positive rates of hTERT mRNA (P 0.05). The expression of hTERT mRNA was correlated with TMN stage, lymph node metastasis and distant metastasis (all P 0.05). The results of diagnostic indices showed that the hTERT mRNA had high sensitivity (84.8%), specificity (82.7%), accuracy (83.7%), positive predictive value (81.2%) and positive likelihood ratio (4.90). CA72-4 also had high specificity (61.2%), accuracy (64.3%), and positive predictive value (45.8%), which were second only to the hTERT mRNA. The diagnostic performance of CA125 combined with CEA, CA72-4, CA19-9 and peripheral blood hTERT mRNA was not significantly different from the latter four combined detection (P > 0.05). The sensitivity and specificity of combined detection of traditional tumor markers CEA, CA72-4 and CA19-9 were 62.5% and 80.0%. The sensitivity and specificity of combined detection of hTERT mRNA, CEA, CA72-4 and CA19-9 could be change to 90.0% and 67.5%. The difference in sensitivity between the two combined detection groups was statistically significant (P = 0.019), and the difference in specificity was not statistically significant (P > 0.05). Conclusion The comprehensive evaluation index of peripheral blood hTERT mRNA is better than the traditional gastric tumor markers, and it is expected to become a new marker for the diagnosis of gastric cancer. Key words: Stomach neoplasms; Diagnosis; Telomerase reverse transcriptase; Tumor markers, biological; Polymerase chain reaction

Strand displacement amplification-coupled dynamic light scattering method to detect urinary telomerase for non-invasive detection of bladder cancer

Despite huge successes achieved by strand displacement amplification (SDA) and gold nanoparticles (AuNPs) in biomolecules sensing, the strategy of combination of SDA and AuNPs-based dynamic light scattering (DLS) for a biomolecule sensing is unexplored. Here we developed a non-invasive, SDA-based DLS method for the diagnosis of bladder cancer by detecting telomerase activity in human urine. In the presence of telomerase, the telomerase substrate (TS) primer was elongated with repeating sequences of (TTAGGG)n, and the resulting product triggers SDA between the hairpin deoxyribonucleic acid (DNA) and the Primer. The SDA product can be recognized by the oligonucleotide-modified AuNPs probes, resulting in DLS measurable AuNPs aggregation. The assay displayed a detection limit of 3 MCF-7 cells with a signal-to-noise ratio of 3 in a dynamic range of 5–1000 cells. The method was simple, reliable and has been successfully applied in the detection of telomerase in urine with good accuracy, selectivity and reproducibility. Moreover, only urine samples from bladder cancer patients induced a significant change in the average hydrodynamic diameter, indicating practical applicability of the method for the non-invasive diagnosis of bladder cancer.

Dual-Mode Au Nanoprobe Based on Surface Enhancement Raman Scattering and Colorimetry for Sensitive Determination of Telomerase Activity Both in Cell Extracts and in the Urine of Patients.

Telomerase is a valuable biomarker, which is highly correlated to cancer diseases. However, the single-mode probe for telomerase detection cannot satisfy the challenge of detection of telomerase activity rapidly, simply with high selectivity, sensitivity, and accuracy both in preliminary diagnosis and in point of care (POC) testing. Therefore, there is an urgent need to develop a robust approach with controllable assembly and high accuracy to consider both the simplification of preliminary diagnosis and POC testing and the quantification requirement for early clinical diagnosis and treatment. Herein, a novel dual-mode Au NPs probe was developed for determination of telomerase activity with controllable assembly and aggregation statement based on surface enhancement Raman scattering (SERS) and colorimetry. In this strategy, an Au dimer-based probe with high uniformity was assembled successfully, telomerase activity was reflected according to the color variations of solution and the Raman intensity of Raman reporter. Taking advantage of the uniformity of Au dimers and the combination of colorimetry and SERS techniques, our strategy determined the telomerase activity with high accuracy, sensitivity, and wide range. The established probe possessed of high selectivity, sensitivity, and accuracy, which was approved as a reliable, intuitional, and convenient approach for detecting telomerase activity.