We combine the telomerase extension reaction and microRNA (miRNA)-induced rolling circle amplification, followed by graphene oxide (GO) and nicking enzyme-assisted signal amplification as a method to analyze telomerase and miRNA-21 in urine samples with the following merits. First, it is a binary assay and can simultaneously output double signals that correspond to the quantities of telomerase and miRNA, respectively. Second, telomerase activity is enhanced by using a DNA molecular beacon probe to inhibit the formation of G-quadruplex. Third, background noise is decreased significantly via introduction of GO. Fourth, performance tests on about 258 urine samples demonstrate that this binary assay can distinguish between urine from bladder cancer patients, those with cystitis, and normal individuals. Finally, this strategy also shows great potential in distinguishing between muscle-invasive bladder cancers and non-muscle-invasive bladder cancers. The proposed strategy will greatly contribute to clinical decision-making and individualized treatments.Keywords: binary assay; bladder cancer; microRNA; muscle-invasive bladder cancers; non-muscle-invasive bladder cancers; signal amplification; telomerase;

We combine the telomerase extension reaction and microRNA (miRNA)-induced rolling circle amplification, followed by graphene oxide (GO) and nicking enzyme-assisted signal amplification as a method to analyze telomerase and miRNA-21 in urine samples with the following merits. First, it is a binary assay and can simultaneously output double signals that correspond to the quantities of telomerase and miRNA, respectively. Second, telomerase activity is enhanced by using a DNA molecular beacon probe to inhibit the formation of G-quadruplex. Third, background noise is decreased significantly via introduction of GO. Fourth, performance tests on about 258 urine samples demonstrate that this binary assay can distinguish between urine from bladder cancer patients, those with cystitis, and normal individuals. Finally, this strategy also shows great potential in distinguishing between muscle-invasive bladder cancers and non-muscle-invasive bladder cancers. The proposed strategy will greatly contribute to clinical decision-making and individualized treatments.Keywords: binary assay; bladder cancer; microRNA; muscle-invasive bladder cancers; non-muscle-invasive bladder cancers; signal amplification; telomerase;

Functional nucleic acids (FNAs)-based biosensors have shown great potential in heavy metal ions detection due to their low-cost and easy to operate merits. However, in most FNAs based fluorescence probes, the ingenious designs of double-labeled (fluorophore and quencher group) DNA sequence, not only bring the annoyance of organic synthesis, but also restrict its use as a robust biosensor in practical duties. In this paper, we design a simple AIEgens functional nucleic acids (AFNAs) probe which consists of only fluorogen but no quencher group. With the help of duplex-specific nuclease (DSN) enzyme based target recycling, high fluorescence signal and superior sensitivity towards Hg2+ are achieved. This robust assay allows for sensitive and selective detection of Hg2+ in real water samples and mapping of intracellular Hg2+, without double-labeling of oligonucleotide with a dye-quencher pair, nor the multiple assay steps.

The fabrication of sensitive sensors with high selectivity is highly desirable for the detection of some important biomarkers, such as nucleic acids, proteins, small molecules and ions. DNA hybridization chain reaction (HCR) and DNA supersandwich self-assembly (SSA) are two prevalent enzyme-free signal amplification strategies to improve sensitivity of the sensors. In this review, we firstly describe the characteristics about DNA HCR and DNA SSA, and then summarize the advances in the one-dimensional DNA nanostructures assisted by HCR and SSA. This review has been divided into three parts according to the two signal amplification methods and highlights recent progress in these two strategies to improve the detection sensitivity of proteins, nucleic acids, small molecules and ions.

Detections of telomerase activity in vitro and in living cells are of great importance for clinical diagnosis of cancer. In this work, an AIEgens-based bioprobe with two fluorescent signals for enhanced monitor of extracellular and intracellular telomerase activity is designed. After addition of telomerase, two positively charged AIEgens (Silole-R and TPE-H) bind to quencher group labeled primer (QP) and the extension repeated units, leading enhancement of two telomerase-triggered fluorescent signals. Furthermore, by combination the wider linear range in vitro and lower background in living cells imaging, the bioprobe is used to detect telomerase extracted from various cell lines (MCF-7, HeLa, E-J, and HLF), 50 bladder cancer patients’ urine samples, 10 normal people’s urine samples, and also applied in mapping telomerase activity inside living cells (MCF-7, HeLa, MDA-MB-231, and HT1080). The results show that this well-designed strategy can successfully detect telomerase activity in vitro and in living cells with high sensitivity, indicating the potential application of this method in cancer cells bioimaging and clinical cancer diagnosis.

The capability to image, as well as control and manipulate single molecules such as nucleic acids (DNA or RNA) can greatly enrich our knowledge of the roles of individual biomolecules in cellular processes and their behavior in native environments. Here we summarize the recent advances of single nucleic acid imaging based on optical observation and force manipulation. We start by discussing the superiority of single molecule image, the central roles nucleic acids play in biosystems, and the significance of single molecule image towards nucleic acids. We then list a series of representative examples in brief to illustrate how nucleic acid of various morphologies has been imaged from different aspects, and what can be learned from such characterizations. Finally, concluding remarks on parts of which should be improved and outlook are outlined.

Monitoring telomerase activity with high sensitive and reliable is of great importance to cancer analysis. In this paper, we report a sensitive and facile method to detect telomerase activity using AIEgens modified probe (TPE-Py-DNA) as a fluorescence reporter and exonuclease III (Exo III) as a signal amplifier. With the aid of telomerase, repeat units (TTAGGG)n are extended from the end of template substrate oligonucleotides (TS primer) that form duplex DNAs with TPE-Py-DNA. Then, Exo III catalyzes the digestion of duplex DNAs, liberating elongation product and releasing hydrophobic TPE-Py. The released hydrophobic TPE-Py aggregate together and produce a telomerase-activity-related fluorescence signal. The liberated product hybridizes with another TPE-Py-DNA probe, starting the second cycle. Finally, we obtain the target-to-signal amplification ratio of 1:N2. This strategy exhibits good performance for detecting clinical urine samples (distinguishing 15 cancer patients’ samples from 8 healthy ones) and checking intracellular telomerase activity (differentiating cell lines including HeLa, MDA-MB-231, MCF-7, A375, HLF and MRC-5 from the cells pretreated with telomerase-related drug), which shows its potential in clinical diagnosis as well as therapeutic monitoring of cancer.Download high-res image (93KB)Download full-size image

Precisely targeted transportation of a long-term tracing regent to a nucleus with low toxicity is one of the most challenging concerns in revealing cancer cell behaviors. Here, we report a dual-targeted peptide-conjugated multifunctional fluorescent probe (cNGR-CPP-NLS-RGD-PyTPE, TCNTP) with aggregation-induced emission (AIE) characteristic, for efficient nucleus-specific imaging and long-term and low-toxicity tracing of cancer cells. TCNTP mainly consists of two components: one is a functionalized combinatorial peptide (TCNT) containing two targeted peptides (cNGR and RGD), a cell-penetrating peptide (CPP) and a nuclear localization signal (NLS), which can specifically bind to a cell surface and effectively enter into the nucleus; the other one is an AIE-active tetraphenylethene derivative (PyTPE, a typical AIEgen) as fluorescence imaging reagent. In the presence of aminopeptidase N (CD13) and integrin αvβ3, TCNTP can specifically bind to both of them using cNGR and RGD, respectively, lighting up its yellow fluorescence. Because it contains CPP, TCNTP can be effectively integrated into the cytoplasm, and then be delivered into the nucleus with the help of NLS. TCNTP exhibited strong fluorescence in the nucleus of CD13 and integrin αvβ3 overexpression cells due to the specific targeting ability, efficient transport capacity and AIE characteristic in a more crowded space. Furthermore, TCNTP can be applied for long-term tracing in living cells, scarcely affecting normal cells with negligible toxicity in more than ten passages.

Developing simple and inexpensive methods to ultrasensitively detect biomarkers is important for medical diagnosis, food analysis and environmental security. In recent years, isothermal amplifications with sensitivity, high speed, specificity, accuracy, and automation have been designed based on interdisciplinary approaches among chemistry, biology, and materials science. In this article, we summarize the advances in nanostructure assisted isothermal amplification in the past two decades for the detection of commercial biomarkers, or biomarkers extracted from cultured cells or patient samples. This article has been divided into three parts according to the ratio of target-to-signal probe in the detection strategy, namely, the N:N amplification ratio, the 1:N amplification ratio, and the 1:N2 amplification ratio.

Herein, we design novel cellulose conjugated mesoporous silica nanoparticle (CLS-MSP) based nanotherapeutics for stimuli responsive intracellular doxorubicin (DOX) delivery. DOX molecules are entrapped in pores of the fabricated mesoporous silica nanoparticles (MSPs) while cellulose is used as an encapsulating material through esterification on the outlet of the pores of the MSPs to avoid premature DOX release under physiological conditions. In in vitro studies, stimuli responsive DOX release is successfully achieved from DOX loaded cellulose conjugated mesoporous silica nanoparticles (DOX/CLS-MSPs) by pH and cellulase triggers. Intracellular accumulation of DOX/CLS-MSPs in human liver cancer cells (HepG2 cells) is investigated through confocal microscope magnification. Cell viability of HepG2 cells is determined as the percentage of the cells incubated with DOX/CLS-MSPs compared with that of non-incubated cells through an MTT assay.

Disruptive variation in intracellular pH and its fluctuations in lysosomes have a close relationship with the more acidic lysosome lumen of cancer cells (pH 4.5–5.5). Traditional lysosome-targeted probes, such as LysoTracker Green DND-26 (LTG) and LysoTracker Red DND-99 (LTR), can fluoresce when the weak base units in the probes are removed after donating protons under the photoinduced electron-transfer (PET) effect. However they can only be used at low concentration to avoid the aggregation-caused quenching (ACQ) effect and are also easily photobleached under continuous excitation irradiation, displaying low photostability. Herein, a tetraphenylethylene (TPE)-based lysosome-targetable fluorescence probe, TPE-CA, was synthesized, which could selectively monitor the pH change in subcellular organelles and exhibited a strong blue emission under an acidic condition with pH = 4. Using crystallographic, NMR and HRMS analyses, the mechanism regarding the pH dependent fluorescent performance of TPE-CA has been illustrated at the molecular level. In addition, experimental results show that TPE-CA is cell-permeable and biocompatible with HeLa, MCF-7 and HLF cells. The punctate fluorescent spots in the co-staining experiment of TPE-CA with LTG and LTR proves that the blue fluorescence spots of TPE-CA are indeed localized in the most acidic lysosome organelles. In particular, TPE-CA also inherits the aggregation-induced emission (AIE) feature of TPE, showing better photostability under continuous UV illumination compared with the commercial dyes (LTG and LTR). These results show that TPE-CA would be beneficial for understanding the acid environment of lysosomes in related cells and organs with potential biological significance.

Single nucleotide polymorphisms (SNPs) are the most abundant genetic polymorphisms and are responsible for many genetic diseases and cancers. In general, SNPs detection is performed by a single probe system (SPS), in which a single probe specifically hybridizes to one target. However, with the use of this method it is hard to improve the hybridization specificity and single mismatched discrimination factors (DF). In addition, the multiprobe system (MPS) requires complex probe designs and introduces at least one auxiliary probe except for the probe complementary to the target, resulting in a complicated detection system. Faced with these difficulties, we perform the SNP detection using a d/l-tryptophan (Trp) guided DNA probe and regulate the DF of electrochemical DNA (E-DNA) sensors by molecular chirality. We show that the DF of the d-Trp incubated E-DNA sensor (d-sensor) is larger than that of the l-sensor. More importantly, we achieve the high specificity by coupling d-Trp and l-Trp incubated E-DNA sensors, and the median DF is 7.21. Furthermore, the specificity of SNP detection can be further improved by supersandwich assay, and the median DF is enlarged to 37.23, which is comparable to that obtained with a multiprobe detection system.

Controlled drug delivery and real-time tracking of drug release in cancer cells are essential for cancer therapy. Herein, we report a protease-responsive prodrug (DOX-FCPPs-PyTPE, DFP) with aggregation-induced emission (AIE) characteristics for controlled drug delivery and precise tracking of drug release in living cells. DFP consists of three components: AIE-active tetraphenylethene (TPE) derivative PyTPE, functionalized cell penetrating peptides (FCPPs) containing a cell penetrating peptide (CPP) and a short protease-responsive peptide (LGLAG) that can be selectively cleaved by a cancer-related enzyme matrix metalloproteinase-2 (MMP-2), and a therapeutic unit (doxorubicin, DOX). Without MMP-2, this prodrug cannot go inside the cells easily. In the presence of MMP-2, DFP can be cleaved into two parts. One is cell penetrating peptides (CPPs) linked DOX, which can easily interact with cell membrane and then go inside the cell with the help of CPPs. Another is the PyTPE modified peptide which will self-aggregate because of the hydrophobic interaction and turn on the yellow fluorescence of PyTPE. The appearance of the yellow fluorescence indicates the release of the therapeutic unit to the cells. The selective delivery of the drug to the MMP-2 positive cells was also confirmed by using the intrinsic red fluorescence of DOX. Our result suggests a new and promising method for controlled drug delivery and real-time tracking of drug release in MMP-2 overexpression cells.

The sensitivity of detection based on biofunctionalized nanopores is limited since the target-to-signal ratio is 1:1. Isothermal amplification is a promising amplification strategy at constant temperature due to its easy operation, quick results, PCR-like sensitivity, low cost and energy efficiency. In the present work, the isothermally amplified detection of Zn2+ is achieved by using a DNA supersandwich structure and Zn2+-requiring DNAzymes. The DNA supersandwich structures, due to the multiple amplification of nucleic acids, heavily plug the nanopore. Simultaneously, the DNA supersandwich structures bond with the sessile probe (SP) of the substrate in the nanopore which partially hybridizes with DNAzymes. In the presence of Zn2+, the Zn2+-requiring DNAzyme cleaves the SP into two fragments, while the DNA supersandwich structures are peeled off and the ionic pathway is unimpeded. A steep drop and a sequential complete recovery of the current occur in the I–V plot when the DNA supersandwich structures are decorated and peeled off. In the present system, the reliable detection limit of Zn2+ is as low as 1 nM. Discrimination between different types of ions (Cu2+, Hg2+, Pb2+) is achieved.

Absorption of ultraviolet (UV) light by nucleic acid could lead to mutations and skin cancers. Traditional damage detection methods based on fluorescence not only need dye/quencher groups but also display relatively high background interference, causing difficulty in synthesis and purification and thus low specificity of detection. Here, by combining rolling circle amplification (RCA) and aggregation-induced emission molecules (AIE), we made up for the defects of traditional methods to some extent and could also differentiate damaged and undamaged DNA. We also studied radiation damage of the p53 gene fragment both from UVA and UVC, although the mechanism of UVA in mutagenesis remains controversial. To amplify the signal-to-background ratio, we ligated the linear p53 (L p53) gene fragment to be a circular p53 (C p53) gene fragment, which is a key component for RCA. The combination of RCA products and positive TPE-Z (quaternized tetraphenylethene salt) molecules induced the aggregation of AIE molecules, and subsequently resulted in significant fluorescence enhancement (the signal for the undamaged DNA is 598% higher than that of the damaged). Compared with the traditional aggregation-caused quenching (ACQ) based fluorescent method, our assay was more sensitive and more specific.

In this study, we develop a new electrochemical aptasensor by coupling two amplification strategies, including a dual signaling strategy and a supersandwich assay. In order to fabricate this aptasensor, a thiolated capture probe (CP) was first self-assembled on the gold electrode surface by Au–S bonds. After the addition of methylene blue (MB) modified signal probe 1 (SP1) and ferrocene (Fc) labeled signal probe 2 (SP2), supersandwich structure DNA, including multiple units of SP1 and SP2, was grown from the CP on the electrode surface. In the presence of ATP, the strong interaction between ATP and its aptamer (CP, SP1) leads to the disassembly of the supersandwich structure and thereby, the release of SP1 and SP2 from the gold electrode surface, resulting in a decrease of the MB and Fc signals. Taking “Signal gainMB + Signal gainFc” as the response signal, ATP can be detected sensitively; the detection limit is 2.1 nM, which is lower than that using either a single-signaling strategy or a traditional sandwich assay alone. Moreover, the new aptasensor also exhibits excellent specificity, selectivity, reliability and applicability. We believe that this new strategy will be helpful for fabricating sensitive and selective electrochemical aptasensors of other biomolecules and small molecules.

Biological nanochannels or nanopores play a crucial role in basic biochemical processes in cells. Artificial nanopores possessing dimensions comparable to the size of biological molecules and mimicking the function of biological ion channels are of particular interest with respect to the design of biosensors with a sensitivity that can go down to the fM level and even to single molecule detection. Nanopore-based analysis (NPA) is currently a new research field with fascinating prospects. This review (with 118 refs.) summarizes the progress made in this field in the recent 10 years. Following an introduction into the fundamentals of NPA, we demonstrate its potential by describing selected methods for sensing (a) proteins such as streptavidin, certain antibodies, or thrombin via aptamers; (b) oligomers, larger nucleic acids, or micro-RNA; (c) small molecules, (d) ions such as K(I) which is vital to the maintenance of life, or Hg(II) which is dangerous to health. We summarize the results and discuss the merits and limitations of the various methods at last.

The enzyme-free toehold-mediated strand displacement reaction has shown potential for building programmable DNA circuits, biosensors, molecular machines and chemical reaction networks. Here we report a simple colorimetric method using gold nanoparticles as signal generators for the real-time detection of the product of the strand displacement cascade. During the process the assembled gold nanoparticles can be separated, resulting in a color change of the solution. This assay can also be applied in complex mixtures, fetal bovine serum, and to detect single-base mismatches. These results suggest that this method could be of general utility to monitor more complex enzyme-free strand displacement reaction-based programmable systems or for further low-cost diagnostic applications.

The influence of long and short polymer chains on the gating properties of nanochannel systems modified with a NIPAAm-co-PBA copolymer have been explored. We not only discovered the negative temperature gating behavior of the NIPAAm modified nanochannel systems for the first time, but also achieve these two fully opposite gating behaviors (negative/positive) on the same platform.

Chirality is one of the fundamental biochemical properties in a living system, and a lot of biological and physiological processes are greatly influenced by the chirality of molecules. Inspired by this phenomenon, we study the covalent assembly of DNA on chiral molecule modified surfaces and further discuss the hybridization of DNA on chiral surfaces with nucleic acids. Take methylene blue (MB) modified DNA as a model molecule, we show that the peak current of the L-NIBC (NIBC, N-isobutyryl-l(d)-cysteine) modified gold surface (L-surface) is larger than the D-surface because of a stronger interaction between short-chain DNA and the L-surface; however, the D-surface has a higher hybridization efficiency than the L-surface. Moreover, we apply this result to actual application by choosing an electrochemical DNA (E-DNA) sensor as a potential platform. Furthermore, we further amplify the difference of hybridization efficiency using the supersandwich assay. More importantly, our findings are successfully employed to program the sensitivity and limit of detection.

Almost all of the important functions of DNA are realized by proteins which interact with specific DNA, which actually happens in a limited space. However, most of the studies about the protein–DNA binding are in an unconfined space. Here, we propose a new method, nanopore-based DNA-probe sequence-evolution (NDPSE), which includes up to 6 different DNA-probe systems successively designed in a nanoscale confined space which unveil the more realistic characteristics of protein–DNA binding phenomena. There are several features; for example, first, the edge-hindrance and core-hindrance contribute differently for the binding events, and second, there is an equilibrium between protein–DNA binding and DNA–DNA hybridization.

Nature owns remarkable capabilities in sensing target molecules, while the artificial biosensor lags far behind nature. Inspired by nature, we devise a new sensing platform that can specifically bind the molecules and synchronously initiate a specific signal response. We rationally designed a type of bipolar probe that is comprised of a hydrophilic DNA part and a hydrophobic conjugated polymer (CP) unit. In aqueous solution, they can form micelles with a hydrophobic CP core and a hydrophilic DNA shell. The aggregation-caused quenching suppresses the fluorescence of CP. Adding telomerase, the hydropathical profile of the bipolar probes is drastically regulated that results in the collapse of micelles and liberates fluorescence simultaneously. The probe has been used in both mimic systems and real urine samples (38 samples). We achieve sensitive and specific detection of telomerase and obtain clearly classification for normal people and cancer patients. It can also be used in a signal off sensor that is used to detect mercury ions.

As a biomarker for early cancer diagnosis, telomerase are one of the promising targets for cancer therapeutics. Inspired by the fluorescent emission principle of aggregation-induced emission fluorogens, we creatively designed an AIE-based turn-on method to detect telomerase activity from cell extracts. A positively charged fluorogen (TPE-Z) is not fluorescent when freely diffused in solution. The fluorescence of TPE-Z is enhanced with the elongation of the DNA strand which could light up telomere elongation process. By exploitation of it, we can detect telomerase activity from different cell lines (E-J, HeLa, MCF-7, and HLF) with high sensitivity and specificity. Moreover, our method is successfully employed to demonstrate the applications in bladder cancer diagnosis (41 urine specimens from bladder cancer patients and 15 urine specimens from normal people are detected). The AIE-based method provides a simple one-pot technique for quantification and monitoring of the telomerase activity and shows great potential for future use in clinical tests.

•Rapid and ultrasensitive screening of mercury ions are achieved by using gold nanoparticles based colorimetric method.•Dual labeling strategy is adopted for sensing signal amplification.•The proposed method is successfully used for analysis of mercury-poisoned animal tissues.Rapid and ultrasensitive detection of trace heavy metal mercury(II) ions (Hg2+) are of significant importance due to the induced serious risks for environment and human health. This presented article reports the gold nanoparticle-based dual labeling colorimetric method (Dual-COLO) for ultrasensitive and rapid detection of Hg2+ using the specific thymine–Hg2+–thymine (T–Hg2+–T) as recognition system and the dual labeling strategy for signal amplification. Both qualitative and quantitative detections of Hg2+ are achieved successfully in aqueous samples. More importantly, the achieved detection limit of 0.005 ng mL−1 (0.025 nM) without any instruments is very competitive to other rapid detection methods even ICP-MS based methods. This Dual-COLO method is also applied directly for real water sample monitoring and, more importantly, applied in analysis of mercury poisoned animal tissues and body fluidic samples, indicating a potentially powerful and promising tool for environmental monitoring and food safety control.

Herein, we report a novel strategy to accelerate the rate of DNA strand replacement reaction (DSRR) by polar organic solvents. DSRR plays a vital role in DNA nanotechnology but prolonged reaction time limits its further advancement. That is why it is extremely important to speed up the rate of DSRR. In this work, we introduce different polar organic solvents in both simple and complicated DSRR systems and observe that the rate constant is much more than in aqueous buffer. The rate acceleration of DSRR by polar organic solvents is very obvious and we believe that this strategy will extend the application of DNA nanotechnology in future.

The specific recognition and programmable assembly properties make DNA a potential material for nanodevices. However, the more intelligent the nanodevice is, the more complicated the structure of the nanodevice is, which limits the speed of DNA assembly. Herein, to address this problem, we investigate the performance of DNA Strand Displacement Reaction (DSDR) in a mixture of polar organic solvents and aqueous buffer and demonstrate that the organic polar solvent can speed up DNA self-assembly efficiently. Taking DSDR in 20% ethanol as an example, first we have demonstrated that the DSDR is highly accelerated in the beginning of the reaction and it can complete 60% of replacement reactions (160% enhancement compared with aqueous buffer) in the first 300 seconds. Secondly, we calculated that the ΔΔG of the DSDR in 20% ethanol (−18.2 kcal mol−1) is lower than that in pure aqueous buffer (−32.6 kcal mol−1), while the activation energy is lowered by introducing ethanol. Finally, we proved that the DSDR on the electrode surface can also be accelerated using this simple strategy. More importantly, to test the efficacy of this approach in nanodevices with a complicated and slow DNA self-assembly process, we apply this strategy in the hybridization chain reaction (HCR) and prove the acceleration is fairly obvious in 20% ethanol, which demonstrates the feasibility of the proposed strategy in DNA nanotechnology and DNA-based biosensors.

Herein, we report natural chitosan end-capped MCM-41 type MSNPs as novel, dual stimuli, responsive nano-vehicles for controlled anticancer drug delivery. The chitosan nanovalves tightly close the pores of the MSNPs to control premature cargo release under physiological conditions but respond to lysozyme and acidic media to release the trapped cargo.

Telomerase, a valuable biomarker, is highly correlated with the development of most of human cancers. Here, we develop a bidirectional strategy for telomerase activity detection and bladder cancer diagnosis based on four detection-color states of difunctional gold nanoparticle (GNP) probes such as blue, purple, red, and precipitate. Specifically, we define the red GNP probe as origin, which represents urine extracts with inactive telomerase and implies normal individuals. The forward direction is corresponding to the detection of a relatively high concentration of active telomerase, in which system GNP probes assemble obviously and precipitate, predicting bladder cancer samples. The negative direction is corresponding to extracts with a relatively low concentration (purple) and without any telomerase (blue), which can be differentiated by naked eyes or UV–vis spectrum, indicating bladder cancer and normal individuals, respectively. More importantly, this noninvasive strategy shows great sensitivity and selectivity when tested by 18 urine specimens from bladder cancer patients, inflammation, and normal individuals.

Through rational design of a functional molecular probe with high sequence specificity that takes advantage of sensitive isothermal amplification with simple operation, we developed a one-pot hairpin-mediated quadratic enzymatic amplification strategy for microRNA (miRNA) detection. Our method exhibits ultrahigh sensitivity toward miR-21 with detection limits of 10 fM at 37 °C and 1 aM at 4 °C, which corresponds to nine strands of miR-21 in a 15 μL sample, and it is capable of distinguishing among miRNA family members. More importantly, the proposed approach is also sensitive and selective when applied to crude extractions from MCF-7 and PC3 cell lines and even patient tissues from intraductal carcinoma and invasive ductal carcinoma of the breast.

Biocomputing, a subarea of unconventional chemical computing, is performed by DNA, protein/enzymes, and other living organisms. Recently, various biomolecular logic gates employing optical changes or PAGE measurements have been studied intensively using various inputs. However, the low detection speed, which is an inherent characteristic of the PAGE method, has prevented it from being developed technologically. Most of the biomolecular logic gates reported to date are mainly based on fluorescence, phosphorescence, or colorimetric outputs, which are laborious, time-consuming, and unsuitable for directly detecting subtle structures. They also suffer the limitations of cumbersomely interfacing the optical outputs with nonmolecular-based technologies. In this context, biomolecular assisted electrochemistry is one of the most popular techniques due to the combined advantages of high sensitivity, specificity, small volume requirements, low cost, and the possibility of mass production via the microelectronic industry. In addition, it is necessary that the future of molecular logic gates elements is strongly related to the successful linkage of molecules onto a conductive or semiconductive support. In this highlight, we will focus on the bioelectronic computing devices based on DNA, enzymes, and biofuel cells.

Precisely targeted transportation of a long-term tracing regent to a nucleus with low toxicity is one of the most challenging concerns in revealing cancer cell behaviors. Here, we report a dual-targeted peptide-conjugated multifunctional fluorescent probe (cNGR-CPP-NLS-RGD-PyTPE, TCNTP) with aggregation-induced emission (AIE) characteristic, for efficient nucleus-specific imaging and long-term and low-toxicity tracing of cancer cells. TCNTP mainly consists of two components: one is a functionalized combinatorial peptide (TCNT) containing two targeted peptides (cNGR and RGD), a cell-penetrating peptide (CPP) and a nuclear localization signal (NLS), which can specifically bind to a cell surface and effectively enter into the nucleus; the other one is an AIE-active tetraphenylethene derivative (PyTPE, a typical AIEgen) as fluorescence imaging reagent. In the presence of aminopeptidase N (CD13) and integrin αvβ3, TCNTP can specifically bind to both of them using cNGR and RGD, respectively, lighting up its yellow fluorescence. Because it contains CPP, TCNTP can be effectively integrated into the cytoplasm, and then be delivered into the nucleus with the help of NLS. TCNTP exhibited strong fluorescence in the nucleus of CD13 and integrin αvβ3 overexpression cells due to the specific targeting ability, efficient transport capacity and AIE characteristic in a more crowded space. Furthermore, TCNTP can be applied for long-term tracing in living cells, scarcely affecting normal cells with negligible toxicity in more than ten passages.

Correction for ‘A photostable AIE fluorogen for lysosome-targetable imaging of living cells’ by Xiaoding Lou et al., J. Mater. Chem. B, 2016, 4, 5412–5417.

Disruptive variation in intracellular pH and its fluctuations in lysosomes have a close relationship with the more acidic lysosome lumen of cancer cells (pH 4.5–5.5). Traditional lysosome-targeted probes, such as LysoTracker Green DND-26 (LTG) and LysoTracker Red DND-99 (LTR), can fluoresce when the weak base units in the probes are removed after donating protons under the photoinduced electron-transfer (PET) effect. However they can only be used at low concentration to avoid the aggregation-caused quenching (ACQ) effect and are also easily photobleached under continuous excitation irradiation, displaying low photostability. Herein, a tetraphenylethylene (TPE)-based lysosome-targetable fluorescence probe, TPE-CA, was synthesized, which could selectively monitor the pH change in subcellular organelles and exhibited a strong blue emission under an acidic condition with pH = 4. Using crystallographic, NMR and HRMS analyses, the mechanism regarding the pH dependent fluorescent performance of TPE-CA has been illustrated at the molecular level. In addition, experimental results show that TPE-CA is cell-permeable and biocompatible with HeLa, MCF-7 and HLF cells. The punctate fluorescent spots in the co-staining experiment of TPE-CA with LTG and LTR proves that the blue fluorescence spots of TPE-CA are indeed localized in the most acidic lysosome organelles. In particular, TPE-CA also inherits the aggregation-induced emission (AIE) feature of TPE, showing better photostability under continuous UV illumination compared with the commercial dyes (LTG and LTR). These results show that TPE-CA would be beneficial for understanding the acid environment of lysosomes in related cells and organs with potential biological significance.

Developing simple and inexpensive methods to ultrasensitively detect biomarkers is important for medical diagnosis, food analysis and environmental security. In recent years, isothermal amplifications with sensitivity, high speed, specificity, accuracy, and automation have been designed based on interdisciplinary approaches among chemistry, biology, and materials science. In this article, we summarize the advances in nanostructure assisted isothermal amplification in the past two decades for the detection of commercial biomarkers, or biomarkers extracted from cultured cells or patient samples. This article has been divided into three parts according to the ratio of target-to-signal probe in the detection strategy, namely, the N:N amplification ratio, the 1:N amplification ratio, and the 1:N2 amplification ratio.

The influence of long and short polymer chains on the gating properties of nanochannel systems modified with a NIPAAm-co-PBA copolymer have been explored. We not only discovered the negative temperature gating behavior of the NIPAAm modified nanochannel systems for the first time, but also achieve these two fully opposite gating behaviors (negative/positive) on the same platform.

Herein, we report natural chitosan end-capped MCM-41 type MSNPs as novel, dual stimuli, responsive nano-vehicles for controlled anticancer drug delivery. The chitosan nanovalves tightly close the pores of the MSNPs to control premature cargo release under physiological conditions but respond to lysozyme and acidic media to release the trapped cargo.