Analysis of Telomerase by the Telomeric Hemin/G-Quadruplex-Controlled Aggregation of Au Nanoparticles in the Presence of Cysteine

Telomerase: a nexus between cancer nanotherapy and circadian rhythm

Cancer represents a complex disease category defined by the unregulated proliferation and dissemination of anomalous cells within the human body. According to the GLOBOCAN 2020 report, the year 2020 witnessed the diagnosis of approximately 19.3 million new cases of cancer and 10.0 million individuals succumbed to the disease. A typical cell eventually becomes cancerous because of a long-term buildup of genetic instability and replicative immortality. Telomerase is a crucial regulator of cancer progression as it induces replicative immortality. In cancer cells, telomerase inhibits apoptosis by elongating the length of the telomeric region, which usually protects the genome from shortening. Many nanoparticles are documented as being available for detecting the presence of telomerase, and many were used as delivery systems to transport drugs. Furthermore, telomere homeostasis is regulated by the circadian time-keeping machinery, leading to 24-hour rhythms in telomerase activity and TERT mRNA expression in mammals. This review provides a comprehensive discussion of various kinds of nanoparticles used in telomerase detection, inhibition, and multiple drug-related pathways, as well as enlightens an imperative association between circadian rhythm and telomerase activity from the perspective of nanoparticle-based anticancer therapeutics.

Amplification-free detection of telomerase activity at the single-cell level via Cas12a-lighting-up single microbeads (Cas12a-LSMBs)

Telomerase overexpresses in almost all cancer cells and has been deemed a universal biomarker for cancer diagnosis and therapy. However, simple and ultrasensitive detection of telomerase activity in single-cells is still a huge challenge. Herein, we wish to report Cas12a-lighting up single microbeads (Cas12a-LSMBs) for ultrasensitive detection of telomerase activity without nucleic acid amplification. In this platform, single-strand DNA reporter (ssDNA reporter)-functionalized single-microbeads (functionalized-SMBs) are employed as a reactor for the trans-cleavage of telomerase-activated CRISPR/Cas12a as well as a reporting unit for fluorescence signal enrichment and visualization. Due to the space-confined effect and signal enrichment mechanism on the surface of the functionalized SMBs, the Cas12a-LSMBs can accurately detect telomerase activity in crude cell lysates with high specificity. Importantly, we have demonstrated that the Cas12a-LSMBs are a reliable and practical tool to detect telomerase activity in single cells and investigate cellular heterogeneity of telomerase activity from cell-to-cell variations.

Activatable G-quadruplex based catalases for signal transduction in biosensing

Discovery of oxidative catalysis with G-quadruplex•hemin constructs prompted a range of exciting developments in the field of biosensor design. Thus, G-quadruplex based DNAzymes with peroxidase activity found a niche as signal transduction modules in a wide range of analytical applications. The ability of nucleic acid scaffolds to recognise a variety of practically meaningful markers and to translate the recognition events into conformational changes powers numerous sensor design possibilities. In this work, we establish a catalase activity of G-quadruplex•hemin scaffolds. Catalase activated hydrogen peroxide decomposition generates molecular oxygen that forms bubbles. Observation of bubbles is a truly equipment free signal readout platform that is highly desirable in limited resources or do-it-yourself environments. We take a preliminary insight into a G-quadruplex structure-folding topology-catalase activity correlation and establish efficient operating conditions. Further, we demonstrate the platform's potential as a signal transduction modality for reporting on biomolecular recognition using an oligonucleotide as a proof-of-concept target. Ultimately, activatable catalases based on G-quadruplex•hemin scaffolds promise to become valuable contributors towards accessible molecular diagnostics applications.

Proximity ligation-transcription circuit-powered exponential amplifications for single-molecule monitoring of telomerase in human cells

We develop a new strategy for single-molecule monitoring of telomerase based on proximity ligation-transcription circuit-powered exponential amplifications. This strategy exhibits high sensitivity with a detection limit of 0.1 aM for the synthetic telomerase product TPC4 in vitro and 1 HeLa cell in vivo. Moreover, it can screen potential inhibitors, discriminate telomerase from interferents, and distinguish cancer cells from normal cells.

Switchable and dynamic G-quadruplexes and their applications

G-Quadruplexes attract growing interest as functional constituents in biology, chemistry, nanotechnology, and material science. In particular, the reversible dynamic reconfiguration of G-quadruplexes provides versatile means to switch DNA nanostructures, reversibly control catalytic functions of DNA assemblies, and switch material properties and functions. The present review article discusses the switchable dynamic reconfiguration of G-quadruplexes as central functional and structural motifs that enable diverse applications in DNA nanotechnology and material science. The dynamic reconfiguration of G-quadruplexes has a major impact on the development of DNA switches and DNA machines. The integration of G-quadruplexes with enzymes yields supramolecular assemblies exhibiting switchable catalytic functions guided by dynamic G-quadruplex topologies. In addition, G-quadruplexes act as important building blocks to operate constitutional dynamic networks and transient dissipative networks mimicking complex biological dynamic circuitries. Furthermore, the integration of G-quadruplexes with DNA nanostructures, such as origami tiles, introduces dynamic and mechanical features into these static frameworks. Beyond the dynamic operation of G-quadruplex structures in solution, the assembly of G-quadruplexes on bulk surfaces such as electrodes or nanoparticles provides versatile means to engineer diverse electrochemical and photoelectrochemical devices and to switch the dynamic aggregation/deaggregation of nanoparticles, leading to nanoparticle assemblies that reveal switchable optical properties. Finally, the functionalization of hydrogels, hydrogel microcapsules, or nanoparticle carriers, such as SiO₂ nanoparticles or metal-organic framework nanoparticles, yields stimuli-responsive materials exhibiting shape-memory, self-healing, and controlled drug release properties. Indeed, G-quadruplex-modified nanomaterials find growing interest in the area of nanomedicine. Beyond the impressive G-quadruplex-based scientific advances achieved to date, exciting future developments are still anticipated. The review addresses these goals by identifying the potential opportunities and challenges ahead of the field in the coming years.

Construction of a Degradation-Free DNA Conjugated Nanoprobe and Its Application in Rapid Field Screening for Sulfur Mustard

Sulfur mustard (SM) is a notorious blistering chemical warfare agent. Rapid field screening for trace SM is of vital significance for the detection of antiterrorism and timely treatment. Here, a visual assay for SM was constructed on the basis of its inhibition for the G-quadruplexes/hemin DNAzyme. Specifically, multiple guanine (G)-rich single stranded oligonucleotides (ssODN) named S1 (80% of G in the total bases), i.e., the precursor for G-quadruplex, which could oxide tetramethylbenzidine (TMB) to its green product, were conjugated on the nonfouling polymer brush grafted magnetic beads (MB@P(C-H)). SM could specifically alkylate the N7 and O6 sites of G in the S1; thus, it failed to form the DNAzyme based signal reporter. It was demonstrated that the nonfouling P(C-H) interface on the magnetic bead (MB) could protect the conjugated ssODN from nuclease degradation, thus ensuring its well sensing performance in complex samples. Under the optimized conditions, this method achieved good sensitivity and selectivity with a limit of detection (LOD) as low as 0.26 μmol L^-1, and the recoveries ranging from 86% to 117% were obtained for different SM spiked real samples. Above all, this method combining low cost and ready operation could be suited for rapid field SM screening in a wide range of environmental matrices.

Nonradioactive direct telomerase activity detection using biotin-labeled primers

Background

Telomerase is a ribonucleoprotein enzyme responsible for maintenance of telomere length which expressed in more than 85% of cancer cells but undetectable in most normal tissue cells. Therefore, telomerase serves as a diagnostic marker of cancers. Two commonly used telomerase activity detection methods, the telomerase repeated amplification protocol (TRAP) and the direct telomerase assay (DTA), have disadvantages that mainly arise from reliance on PCR amplification or the use of an isotope. A safe, low‐cost and reliable telomerase activity detection method is still lacking.

Method

We modified DTA method using biotin‐labeled primers (Biotin‐DTA) and optimized the method by adjusting cell culture temperature and KCl concentration. The sensitivity of the method was confirmed to detect endogenous telomerase activity. The reliability was verified by detection of telomerase activity of published telomerase regulators. The stability was confirmed by comparing the method with TRAP method.

Results

Cells cultured in 32°C and KCl concentration at 200 mM or 250 mM resulted in robust Biotin‐DTA signal. Endogenous telomerase activity can be detected, which suggested an similar sensitivity as DTA using radioactive isotope markers. Knockdown of telomerase assembly regulator PES1 and DKC1 efficiently reduced telomerase activity. Compared with TRAP method, Biotin‐DTA assay offers greater signal stability over a range of analyte protein amounts.

Conclusion

Biotin‐labeled, PCR‐free, and nonradioactive direct telomerase assay is a promising new method for the easy, low‐cost, and quantitative detection of telomerase activity.

Gold nanoparticle based colorimetric assay of telomerase activity using the cyclic strand displacement reaction

A facile colorimetric assay is developed for the detection of telomerase activity based on the cyclic strand displacement reaction.

Sensitive detection of intracellular telomerase activity via double signal amplification and ratiometric fluorescence resonance energy transfer

As an important and universal tumor marker, the reliable and in situ detection of intracellular telomerase activity is crucial for cancer diagnosis. Herein, a ratiometric fluorescence resonance energy transfer (FRET) method was developed for detecting intracellular telomerase activity. It takes full advantage of manganese dioxide nanosheets (MnO2NS) that can carry DNA probes with different conformations into cells and then completely release the DNA probes via decomposition of MnO2NS by intracellular reduced glutathione (GSH). In the presence of telomerase, a telomere substrate (TS) could be extended to form long telomerase extension products (TEPs), which trigger the cycling strand displacement reaction (SDR) between two fluorophore-labeled hairpin DNA probes to form lots of DNA duplexes. The close contact of two fluorophores led to an effective ratiometric FRET for reliable detection of telomerase activity. Fluorescence confocal imaging demonstrated that the activity of telomerase in tumor cells was reliably detected. The inhibition of telomerase activity by an inhibitor resulted in a decrease in FRET signal. For extracellular detection, the FRET ratio (FA/FD) shows a good linear relationship with the number of HeLa cells in the range of 20-1000 cells. Therefore, it offers a more facile method for reliable and sensitive detection of intracellular telomerase activity.

Portable glucose meter-utilized label-free and washing-free telomerase assay

We herein describe a portable glucose meter (PGM)-utilized label-free and washing-free method for the facile determination of telomerase activity that relies on the kinase-catalyzed cascade enzymatic reaction (KCER) that transduces the telomerase activity to the glucose level. In the sensor, the telomerase that elongates telomere sequences ((TTAGGG)_n) from the 3'-terminus of telomerase substrate primer (TSP) consumes deoxynucleoside triphosphate (dNTP), which serves as a phosphate source for KCER promoted by hexokinase and pyruvate kinase. Thus, the presence of telomerase protects KCER from working effectively, resulting in the maintenance of an initial, high glucose level that is readily determined using hand-held PGM. With this strategy, the telomerase activities in various types of cell lines were successfully determined with high sensitivity. Furthermore, the ability of this method to screen candidate inhibitors for telomerase activity was also verified.

Enzyme-mimicking accelerated signal enhancement for visually multiplexed quantitation of telomerase activity

Here, we propose an amplification strategy involving enzyme-mimicking accelerated signal enhancement integrated with a triple-channel volumetric bar-chart chip for visually multiplexed quantitation of telomerase activity. This platform was used for evaluating the telomerase activities from different kinds of cells and a detection limit at the single-cell level was realized without any instrumental assistance.

A seesaw ratiometric probe for dual-spectrum imaging and detection of telomerase activity in single living cells

Herein, a seesaw ratiometric (SR) probe is designed which integrates fluorescence and surface enhanced Raman scattering (SERS) technology. Fluorescence imaging enables tracking of the spatiotemporal dynamic behaviour of telomerase. Meanwhile, SERS reverse ratiometric measurement can enable sensitive detection of telomerase activity in single living cells.

A highly sensitive and low-background fluorescence assay for pesticides residues based on hybridization chain reaction amplification assisted by magnetic separation

Due to the concern over food safety, it is important to detect the pesticides residues in agricultural products. Here, a highly sensitive and low background fluorescent strategy for the detection of pesticides residues has been developed. The fluorescence intensity of N-methyl mesoporphyrin IX (NMM) binding G-quadruplex could be turn off because of inhibiting effect of the pesticides on the acetylcholinesterase (AChE) activity. For that, four single-stranded DNAs (named linker, trigger, H1 and H2, respectively) are rational designed and T-Hg-T mismatches duplex DNAs as a recognizer combined with the separation of magnetic beads. The design of hybridization chain reaction (HCR) amplification strategy assisted by magnetic separation has been adopted to improve the detection sensitivity. In the presence of pesticides, the amount of the thiol group generated by hydrolysis reaction of acetylcholine (ACh) is reduced, lead to release of less trigger DNA. Therefor subsequent HCR process is retarded with decreased fluorescence intensity. The reduced fluorescence intensity has a quantitative relationship with the pesticide concentration. The limit of detection of chlorpyrifos was estimated to be 2.0 ng ml-1. It has been applied to detect the pesticides residues in real samples.

Advances in optical assays for detecting telomerase activity

Telomerase uses its RNA as template and its protein unit as reverse transcriptase to synthesize TTAGGG repeats at the ends of the eukaryotic chromosome to maintain the lengths of telomeres. Telomerase activity up-regulates in about 85% of human tumors compared with somatic cells, which indicates that telomerase is a tumor biomarker. Reliable assay of telomerase activity is thus essential in diagnosis and management of malignant tumors. In this review, recent developed optical assays are summarized based on the readout signal, including chemiluminescence assay, colorimetric assay, and fluorescence assay.

DNA Quadruple Helices in Nanotechnology

DNA has played an early and powerful role in the development of bottom-up nanotechnologies, not least because of DNA's precise, predictable, and controllable properties of assembly on the nanometer scale. Watson-Crick complementarity has been used to build complex 2D and 3D architectures and design a number of nanometer-scale systems for molecular computing, transport, motors, and biosensing applications. Most of such devices are built with classical B-DNA helices and involve classical A-T/U and G-C base pairs. However, in addition to the above components underlying the iconic double helix, a number of alternative pairing schemes of nucleobases are known. This review focuses on two of these noncanonical classes of DNA helices: G-quadruplexes and the i-motif. The unique properties of these two classes of DNA helix have been utilized toward some remarkable constructions and applications: G-wires; nanostructures such as DNA origami; reconfigurable structures and nanodevices; the formation and utilization of hemin-utilizing DNAzymes, capable of generating varied outputs from biosensing nanostructures; composite nanostructures made up of DNA as well as inorganic materials; and the construction of nanocarriers that show promise for the therapeutics of diseases.

One-pot detection of telomerase activity with high sensitivity and specificity via RNA FRET probes and RNase H-assisted signal cycling amplification

Human telomerase is a universal cancer biomarker and a promising anticancer therapeutic target. Sensitive and specific detection of telomerase activity is of great significance for cancer diagnosis and treatment. Up to now, many methods have been established to detect the activity of telomerase, but most of these methods require complex probe design and tedious experimental steps generally including telomere extension reaction, amplification of the extended products and signal detection. Herein, we propose a one-pot method to detect the telomerase activity via RNA FRET probes and RNase H-assisted signal cycling amplification, and the proposed assay can integrate the telomere extension reaction, signal amplification and readout in one step without requirement of amplification of the extended products, which greatly simplifies the experimental design and operation steps. Additionally, the proposed one-pot method has high sensitivity and can unequivocally detect the telomerase activity in as few as 5 cancer cells, which holds great potential in telomerase-related fundamental and clinical studies.

A one-pot method is developed for the detection of telomerase activity via RNA FRET probes and RNase H-assisted signal cycling amplification.

Quantum dot-based electrochemical biosensor for stripping voltammetric detection of telomerase at the single-cell level

Human telomerase is responsible for the maintenance of chromosome end structures and is a valuable biomarker for malignant growth. However, the accurate measurement of telomerase activity at the single-cell level has remained a great challenge. Here we develop a simple quantum dot (QD)-based electrochemical biosensor for stripping voltammetric detection of telomerase activity at the single-cell level. We designed a thiol-modified capture DNA which may be immobilized on the gold electrode by the gold-sulfur bond. The presence of telomerase enables the addition of the telomere repeats of (TTAGGG)_n to the 3' end of the primer, accompanied by the incorporation of abundant biotins in the extension product with the assistance of the biotin-tagged dATP. The subsequent hybridization of extension product with the capture DNA and the addition of streptavidin-coated QDs induce the assembly of large amounts of QDs onto the electrode via specific biotin-streptavidin binding. After the acidic dissolution of QDs, the released Cd (II) can be simply quantified by anodic stripping voltammetry (ASV). Due to the introduction of large amounts of QDs by telomerase-induced primer extension reaction and the synergistic signal amplification induced by the release of Cd (II) from the QDs, this biosensor can detect telomerase activity at the single-cell level without the involvement of any thermal cycling and extra enzymes for signal amplification. Moreover, this assay exhibits a large dynamic range over four orders of magnitude and it is very simple without the involvement of specific hairpin probe design and complicated labelling, holding great potential in point-of-need testing.

Label-Free and Ultrasensitive Biomolecule Detection Based on Aggregation Induced Emission Fluorogen via Target-Triggered Hemin/G-Quadruplex-Catalyzed Oxidation Reaction

Fluorescence biosensing strategy has drawn substantial attention due to their advantages of simplicity, convenience, sensitivity, and selectivity, but unsatisfactory structure stability, low fluorescence quantum yield, high cost of labeling, and strict reaction conditions associated with current fluorescence methods severely prohibit their potential application. To address these challenges, we herein propose an ultrasensitive label-free fluorescence biosensor by integrating hemin/G-quadruplex-catalyzed oxidation reaction with aggregation induced emission (AIE) fluorogen-based system. l-Cysteine/TPE-M, which is carefully and elaborately designed and developed, obviously contributes to strong fluorescence emission. In the presence of G-rich DNA along with K⁺ and hemin, efficient destruction of l-cysteine occurs due to hemin/G-quadruplex-catalyzed oxidation reactions. As a result, highly sensitive fluorescence detection of G-rich DNA is readily realized, with a detection limit down to 33 pM. As a validation for the further development of the proposed strategy, we also successfully construct ultrasensitive platforms for microRNA by incorporating the l-cysteine/TPE-M system with target-triggered cyclic amplification reaction. Thus, this proposed strategy is anticipated to find use in basic biochemical research and clinical diagnosis.

A facile graphene oxide-based fluorescent nanosensor for the in situ “turn-on” detection of telomerase activity

A graphene oxide-based fluorescent nanosensor has been proposed for the quantitative detection of telomerase and in situ imaging of intracellular telomerase.

Gold nanoparticle-based colorimetric biosensors

Gold nanoparticles (AuNPs) provide excellent platforms for the development of colorimetric biosensors as they can be easily functionalised, displaying different colours depending on their size, shape and state of aggregation. In the last decade, a variety of biosensors have been developed to exploit the extent of colour changes as nano-particles (NPs) either aggregate or disperse, in the presence of analytes. Of critical importance to the design of these methods is that the behaviour of the systems has to be reproducible and predictable. Much has been accomplished in understanding the interactions between a variety of substrates and AuNPs, and how these interactions can be harnessed as colorimetric reporters in biosensors. However, despite these developments, only a few biosensors have been used in practice for the detection of analytes in biological samples. The transition from proof of concept to market biosensors requires extensive long-term reliability and shelf life testing, and modification of protocols and design features to make them safe and easy to use by the population at large. Developments in the next decade will see the adoption of user friendly biosensors for point-of-care and medical diagnosis as innovations are brought to improve the analytical performances and usability of the current designs. This review discusses the mechanisms, strategies, recent advances and perspectives for the use of AuNPs as colorimetric biosensors.

Advances in the detection of telomerase activity using isothermal amplification

Telomerase plays a significantly important role in keeping the telomere length of a chromosome. Telomerase overexpresses in nearly all tumor cells, suggesting that telomerase could be not only a promising biomarker but also a potential therapeutic target for cancers. Therefore, numerous efforts focusing on the detection of telomerase activity have been reported from polymerase chain reaction (PCR)-based telomeric repeat amplification protocol (TRAP) assays to PCR-free assays such as isothermal amplification in recent decade. In this review, we highlight the strategies for the detection of telomerase activity using isothermal amplification and discuss some of the challenges in designing future telomerase assays as well.

Sensing telomerase: From in vitro detection to in vivo imaging

Telomerase is a ribonucleoprotein reverse transcriptase that is responsible for maintaining the telomere length in cells. Telomerase overexpresses in almost all malignant tumor cells, and it has become a promising biomarker and a potential therapy target for cancers. Consequently, accurate and efficient quantification of the telomerase is highly essential to medical diagnostics and therapeutics. Recently, a series of novel telomerase detection methods with excellent performance have been developed, but a overview of in vivo telomerase detection methods is lacking. In this Minireview, we summarize the emerging strategies for telomerase assays in the last five years, including both in vitro assays and in vivo imaging methods, and discuss their future directions as well.

An ultra-sensitive colorimetric assay for reliable visual detection of telomerase activity

We proposed a sensitive colorimetric assay for detecting telomerase activity. The telomerase activity of 5 and 20 HeLa cell lysates can be detected via UV-vis spectroscopy and the naked eye, respectively.

Evaluation of intracellular telomerase activity through cascade DNA logic gates

Telomerase plays a vital role in cancer and aging, and telomerase activity detection has drawn great attention recently. However, a feasible in situ imaging system for intracellular telomerase is still a challenge. Here, we develop a novel approach to image intracellular telomerase activity using DNA-based computation. A cascade nucleic acid logic gate that responded to intracellular telomerase was constructed. A telomerase substrate (TS) probe, extended by intracellular telomerase, worked as an input to initiate computation cascades. In this way, intracellular telomerase could be clearly indicated by fluorophore labeled nucleic acids as the output. Through one-step incubation, evaluation of the intracellular telomerase activity for a HeLa cell line and the ability to differentiate cancer cells from normal cells could be realized. Furthermore, the response of intracellular telomerase activity to a telomerase-inhibiting model drug was observed using the proposed method. Thus, this intracellular telomerase computation device will allow improvements in studying the relationship between telomerase and cancer, and may help to develop telomerase inhibitors. This finding also expands the applications of DNA computational techniques in cells.

Nanoparticle-Aided Amplification of Fluorescence Polarization for Ultrasensitively Monitoring Activity of Telomerase

To realize facile and reliable analyzing telomerase activity in homogeneous, herein, for the first time, a fluorescent polarization (FP) strategy was developed for polymerase chain reaction (PCR) free monitoring activity of human telomerase at single-cell level ground on gold nanoparticle (GNP) enhancement of FP. First, thiolated telomerase substrate (TS) primer is modified to the surface of GNP via Au-S bond. In the presence of telomerase, TS primer was extended via adding hexamer repeats (GGGTTA), leading to the formation of a long elongation DNA. Several short carboxyfluorescein (FAM)-modified complementary DNA (F-cDNA) can hybridize with the hexamer repeats, resulting in a sharp increase in FP value. Because of the GNP enhancement and self-amplification of telomerase, telomerase activity accounting to one HeLa cell can be rapidly detected in homogeneous solution. Telomerase activities of various cell lines were also favorably estimated. Meanwhile, the inhibition efficiency of telomerase inhibitor was studied, which holds great potential in screening telomerase-targeted anticancer drugs as well. So, a facile method was put forward to reliably and ultrasensitively detect telomerase activity.

Telomerase inhibitors: a patent review (2010-2015)

INTRODUCTION

Telomerase is a ribonucleoprotein that catalyses the addition of telomeric repeat sequences (having the sequence 5'-TTAGGG-3' in humans) to the ends of chromosomes. Telomerase activity is detected in most types of human tumours, but it is almost undetectable in normal somatic cells. Therefore, telomerase is a promising therapeutic target. To date, the known inhibitors of telomerase include nucleoside analogues, oligonucleotides and G-quadruplex stabilizers. This review highlights recent advances in our understanding of telomerase inhibitors, the relationships between telomerase inhibitors, cancer, and fields such as inflammation.

AREAS COVERED

This review summarizes new patents published on telomerase inhibitors from 2010 to 2015.

EXPERT OPINION

The review provides a brief account of the background, development, and on-going issues involving telomerase inhibitors. In particular, this review emphasizes imetelstat (GRN163L) and some typical G-quadruplex stabilizers that participate in telomerase inhibition. Overall, the research scope of antineoplastic is becoming broader and telomerase inhibitors have been shown to be a promising therapeutic target. Therefore, novel antineoplastic agents with greater activity and higher specificity must be developed.

Coupling a DNA-Based Machine with Glucometer Readouts for Amplified Detection of Telomerase Activity in Cancer Cells

The strong correlation between cancer and telomerase activity has inspired the development of new strategies to evaluate telomerase activity. Here, a personal glucose meter (PGM) system that uses DNA-based machine amplification to detect telomerase in cancer cells is reported. In this assay, telomerase elongation products are amplified in the form of another type of product by a DNA-based machine. This process can only be activated by the hybridization of the extended telomerase substrate (TS) probe and the complementary primer in the presence of telomerase. The obtained products are then transformed to glucose-related signals via a three-component assay, which enables the simple use of a PGM to indirectly quantify the telomerase activity. The proposed method realizes sensitive telomerase activity detection down to 20 HeLa cells with a significantly enhanced dynamic range. Additionally, short telomerase elongation products, such as telomerase substrate probes with two repetitive sequences, that cannot be detected using the most widely used telomeric repeat amplification protocol assay were detected.

Supramolecular micelle-based nucleoapzymes for the catalytic oxidation of dopamine to aminochrome

Lipidated DNAzymes or a lipidated Cu(ii)-complex and lipidated aptamer sequences form supramolecular assemblies of micellar nucleoapzymes for the enhanced oxidation of dopamine to aminochrome.