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Assessment of fetal maturity is essential for timely termination of pregnancy, especially in pregnant women with pregnancy complications. However, there is a lack of methods to assess the maturity of fetal intestinal function. Here, we constructed erythrocyte membrane-camouflaged aggregation-induced emission (AIE) nanoparticles. Nanocore is formed using a hollow mesoporous silicon nanobox (HMSN) of different particle sizes loaded with AIE luminogens -PyTPA (P), which are then co-extruded with erythrocyte membranes (M) to construct M@HMSN@P. The 100 nm M@HMSN@P has a more effective cellular uptake efficiency in vitro and in vivo. Swallowing and intestinal function in fetal mice mature with the increase in gestational age. After intrauterine injection of M@HMSN@P, they were swallowed and absorbed by fetal mice, and their swallowed and absorbed amount was positively correlated with the gestational age with a correlation coefficient of 0.9625. Using the M@HMSN@P (fluorescence intensity) in fetal mice, the gestational age can be imputed, and the difference between this imputed gestational age and the actual gestational age is less than 1 day. Importantly, M@HMSN@P has no side effect on the health status of pregnant and fetal mice, showing good biocompatibility. In conclusion, we constructed M@HMSN@P nanoparticles with different particle sizes and confirmed that the smaller size M@HMSN@P has more efficient absorption efficiency and it can assess fetal intestinal maturity by the intensity of the fluorescence signal.

Solid-state nanopores, inspired by biological nanopores, have the advantages of good mechanical properties, stability, and easy modification. They have attracted wide attention in the fields of sequencing, sensing, molecular sieving, nanofluidic devices, nanoelectrochemistry, and energy conversion. Because of the ion/molecule transport characteristic of the pore, the research on solid-state nanopores mainly focuses on the functional modification of its inner wall. In recent years, the outer surface of nanopores has also attracted the attention of researchers, and the functional elements on the outer surface have the functions of anti-interference and ionic signal enhancement. In this perspective, we review research progress of inner wall and outer surface distinguished solid-state nanopores, highlight their processing and advantages, summarize their functions and applications in sensing, and give insight into further research.

Before arriving at the intracellular destinations, probes might be trapped in the lysosomes, reducing the amount of cargos, which compromises the therapeutic outcomes. The current methods are based on the fact that probes enter the lysosomes and then escape from them, which do not fundamentally solve the degradation by lysosomal hydrolases. Here, an enzyme-responsive modular peptide probe named PKP that can be divided into two parts, Pal-part and KP-part, by matrix metalloproteinase-2 (MMP-2) overexpressed in tumor microenvironments is designed. Pal-part quickly enters the cells and forms nanofibers in the lysosomes, decreasing protein phosphatase 2A (PP2A), which transforms the endocytic pathway of KP-part from clathrin-mediated endocytosis (CME) into caveolae-mediated endocytosis (CvME) and allows KP-part to directly reach the mitochondria sites without passing through the lysosomes. Finally, through self-regulating intracellular delivery pathways, the mitochondrial delivery efficiency of KP-part is greatly improved, leading to an optimized image-guided therapeutic efficiency. Furthermore, this system also shows great potential for the delivery of siRNA and doxorubicin to achieve precise cancer image-guided therapy, which is expected to significantly expand its application and facilitate the development of personalized therapy.

Although the CRISPR/Cas system has pioneered a new generation of analytical techniques, there remain many challenges in developing a label-free, accurate, and reliable CRISPR/Cas-based assay for reporting the levels of low abundance biomolecules in complex biological samples. Here, we reported a novel CRISPR-derived resonance Rayleigh scattering (RRS) amplification strategy and logical circuit based on a guanine nanowire (G-wire) assisted non-cross-linking hybridization chain reaction (GWancHCR) for label-free detection of lipopolysaccharide (LPS). In the presence of a target, the protospacer-adjacent motif-inserted aptamer is rationally designed to specifically combine with LPS rather than Cas12a, suppressing the trans-cleavage activity of CRISPR/Cas12a and retaining the reporter probes to trigger non-cross-linking aggregation. Owing to the automatic hybridization chain reaction (HCR), in the presence of Mg

By maintaining the telomere lengths, telomerase can make the tumor cells avoid the apoptosis, thus, achieving the cell immortalization. In the past, a series of telomerase detection systems have been developed through utilizing the unique characteristic of telomerase extended primer. However, fluctuation of telomerase activity, along with the cell cycle progression, leads to ambiguous detection results. Here, we reported a dual signal output detection strategy based on cell-cycle synchronization for precisely detecting telomerase activities by using a new AIEgen probe SSNB. Experimental and simulating calculation results demonstrated that positively charged SSNB could interact with DNA through the electrostatic interaction and π-π interaction, as well as the hydrogen bonds. The aggregation of SSNB caused by the extended template strand primer (TP) could be observed in tumor cells, thus, indicating the telomerase activity in various cell lines. Furthermore, after cell cycle synchronization, it was found that the telomerase activity in the S phase was the highest, no matter from the fluorescence intensity or the ROS generation situation. Dual signal outputs of SSNB verified the significance and necessity of cell-cycle synchronization detection for telomerase activity. This strategy could open a new window for the biotargets of which activity is variational in time dimension.

Surface charge effects in nanoconfines is one of the fundamentals in the ion current rectification (ICR) of nanofluidics, which provides entropic driving force by asymmetric surface charges and causes ion enrichment/depletion by the electrostatic interaction of fixed surface charges. However, the surface charge effect causes a significant electrostatic repulsion in nanoconfines, restricting additional like charge or elaborate chemistry on the highly charged confined surface, which limits ICR manipulation. Here, we use polydopamine (PDA), a nearly universal adhesive, that adheres to the highly positive-charged poly(ethyleneimine) (PEI) gel network in a nanochannel array. PDA enhances the ICR effect from a low rectification ratio of 9.5 to 92.6 by increasing the surface charge and hydrophobicity of the PEI gel network and, meanwhile, shrinking its gap spacing. Theoretical and experimental results demonstrate the determinants of the fixed surface charge in the enrichment/depletion region on ICR properties, which is adjustable by PDA-induced change in a nanoconfined environment. Chemically active PDA brings Au nanoparticles by chloroauric reduction for further hydrophobization and the modification of negative-charged DNA complexes in nanochannels, whereby ICR effects can be manipulated in versatile means. The results describe an adjustable and versatile strategy for adjusting the ICR behaviors of nanofluidics by manipulating local surface charge effects using PDA.

Utilizing ionic current and fluorescent dual-signal-output nanochannels to achieve the detection of specific target species has received much attention. The introduction of an optical signal could not only improve the selectivity of the detection systems, but also make it possible to observe the reduction of the ionic current that originated from stimulus-triggered nanochannel changes. However, the resolution of an optical signal can only verify issues of the presence or absence and cannot precisely analyze the detailed chemical structural changes within nanochannels. Here, we employed a biocompatible condensation reaction between 2-cyanobenzothiazole (CBT) and d-cysteine, and synthesized molecules PCTC that can be polymerized by cutting off short peptide sequences in the presence of furin to realize the detection of furin with multiple signal outputs. Through the introduction of a UV light-sensitive DNA sequence to the capture probes (CPs) inside the nanochannels, the blocking of the nanochannels can be confirmed to the formed oligomers by mass spectrometry analysis.

Probe-modified nanopores/nanochannels are one of the most advanced sensors because the probes interact strongly with ions and targets in nanoconfinement and create a sensitive and selective ionic signal. Recently, ionic signals have been demonstrated to be sensitive to the probe-target interaction on the outer surface of nanopores/nanochannels, which can offer more open space for target recognition and signal conversion than nanoconfined cavities. To enhance the ionic signal, we investigated the effect of grafting density, a critical parameter of the sensing interface, of the probe on the outer surface of nanochannels on the change rate of the ionic signal before and after target recognition (β). Electroneutral peptide nucleic acids and negatively charged DNA are selected as probes and targets, respectively. The experimental results showed that when adding the same number of targets, the β value increased with the probe grafting density on the outer surface. A theoretical model with clearly defined physical properties of each probe and target has been established. Numerical simulations suggest that the decrease of the background current and the aggregation of targets at the mouth of nanochannels with increasing probe grafting density contribute to this enhancement. This work reveals the signal mechanism of probe-target recognition on the outer surface of nanochannels and suggests a general approach to the nanochannel/nanopore design leading to sensitivity improvement on the basis of relatively good selectivity.

The nanofluidic ionic signal is governed by the interactions between ion species and the surface charge, surface wettability, and pore diameter of nanofluidic membranes. However, the effect of surface wettability on the ionic detection signal across the nanofluidic membrane remains poorly explored, limited nanofluidic applications in biochemical sensing. Here, we investigate the effect of surface wettability of the nanofluidic membrane on the ionic signal for the detection of hydrophobic drug molecules using a heterogeneous nanofluidic system. This ionic signal can be tuned by light or the presence of certain ions due to the tailoring of hydrophobic interactions between the ion species and membrane surface. Compared with traditional nanofluidic membranes whose ionic signal is governed by surface charge, the regulation mechanism reported here mainly dependents on specific hydrophobic interactions, which shows a more sensitive ionic signal to environments. By virtue of the mechanism, the selective detection of the three drug molecules was realized owing to their different hydrophobic interactions with membrane surfaces. These findings have implications for understanding mass transport in nanofluidic devices and biological components and porous media involving surface wettability in nanofluidic systems.

The subcellular distribution of adenosine 5'-triphosphate (ATP) and the concentration of ATP in living cells dynamically fluctuate with time during different cell cycles. The dictated activation of the biosensing process in living cells enables the spatiotemporal target detection in single living cells. Herein, a kind of o-nitrobenzylphosphate ester hairpin nucleic acid was introduced as a photoresponsive DNA probe for light-activated ATP detection in single living cells. Two methods to spatiotemporally activate the probe in single living cells were discussed. One method was the usage of the micrometer-sized optical fiber (about 5 μm) to guide the UV light (λ = 365 nm) to selectively activate the photoresponsive DNA probe in single living cells. The second method involved a two-photon laser confocal scanning microscope to selectively irradiate the photoresponsive DNA probes confined in single living cells via two-photon irradiation (λ = 740 nm). ATP aptamer integrated in the activated DNA probes selectively interacted with the target ATP, resulting in dictated signal generation. Furthermore, the photoactivated biosensing process enables dictated dual-model ATP detection in single living cells with "Signal-ON" fluorescence signal and "Signal-OFF" electrochemical signal outputs. The developed photoactivated biosensor for dictated ATP detection with high spatiotemporal resolution in single living cells at a desired time and desired place suggests the possibility to monitor biomarkers during different cell cycles.

Hybridization chain reaction (HCR) amplification strategy has been extensively explored for the application of electrochemical DNA-based sensors. Despite the enhancement in its sensitivity using the HCR, such sensor platform exhibited significant sensor-to-sensor variations in current due to variations in probe counts and lengths. To circumvent this, we are developing here a calibration-free "O-N" approach to generate a ratiometric, unitless value that is independent of these variations. Specifically, this approach employs two types of redox reporters, denoted as "One reporter" and "N reporters", with the former attached on the capture DNA and the latter on H1 and H2 strands. By optimizing the attachment sites of these reporters onto DNA strands, we demonstrate a significantly enhanced sensitivity of such sensor platform by four orders of magnitude, achieving accurate, calibration-free measurement of nucleic acids including ctDNA directly in undiluted whole blood without the requirement to calibrate each individual sensor.

The grafting density of probes at sensor interface plays a critical role in the performance of biochemical sensors. However, compared with macroscopic interface, the effects of probe grafting density at nanometric confinement are rarely studied due to the limitation of precise grafting density regulation and characterization at the nanoscale. Here, we investigate the effect from the grafting density of DNA probes on ionic signal for nucleic acid detection in a cylindrical nanochannel array (with diameter of 25 nm) by combing experiments and theories. We set up a theoretical model of charge distribution from close to inner wall of nanochannels at low probe grafting density to spreading in whole space at high probe grafting density. The theoretical results fit well with the experimental results. A reverse of ionic output from signal-off to signal-on occurs with increasing probe grafting density. Low probe grafting density offers a high current change ratio that is further enhanced using long-chain DNA probes or the electrolyte with a low salt concentration. This work develops an approach to enhance performance of nanochannel-based sensors and explore physicochemical properties in nanometric confines.

The rational design of DNA capture probes for modulating the binding affinity to tune the dynamic range of electrochemical DNA (E-DNA) biosensors is valuable and effective. Most of current strategies, however, require designing several DNA capture probes to achieve the tunable dynamic range, which is cumbersome and costly. Herein, we develop the photoresponsive E-DNA biosensors with tunable dynamic ranges by using only one photocleavable capture probe (PC-CP). The photoresponsive PC-CP is a stem-loop DNA structure containing a photocleavable linker (PC-linker) in the loop. The PC-linker can be cleaved by UV irradiation to switch the structure of PC-CP, through which the binding affinity to the target could be tuned. In this way, the dynamic range, the sensitivity, and the specificity of photoresponsive E-DNA biosensors can be tuned. Furthermore, the developed photoresponsive E-DNA biosensors enable sensitive and selective detection of target DNA in complex samples with a tunable dynamic range, which offers the possibility of clinical applications.

The expression level and subcellular distribution of mRNA dynamically changed during the different cell circles. Spatiotemporally controllable signal amplification methods capable of controlling the when and where of the amplification process could allow the sensitive mRNA imaging of selected living cells at dictated time-intervals of the cell life-cycle. However, the present methods for amplified mRNA imaging are hard to control the where and when of the signal amplification due to the lack of an effective strategy to precisely trigger and control the signal amplification process. Herein, we present a conceptual study termed as photocontrollable nucleic acid cascade recycling amplification which uses near-infrared (NIR) light to precisely control and trigger the whole process. This strategy is achieved by integrating photocontrollable nucleic acid displacement reaction with exonuclease III (EXO III) assisted nucleic acid cascade recycling amplification and combination with upconversion nanoparticles (UCNPs), thus resulting in a NIR light activatable signal amplification. As a proof of concept, we demonstrate this developed NIR light triggered signal amplification process in selected living cancer cells for spatiotemporally controllable signal amplified mRNA imaging.

Determining the expression level of biomarkers is crucial for disease diagnosis. However, the low abundance of biomarkers in the early stage makes the detection extremely difficult by traditional aggregation-induced emission (AIE)-based fluorescent probes. Here, by tuning the intermolecular interaction, a two steps-based MP/NPs-SLIPS sensing system is designed for ultrasensitive detection of the tumor marker matrix metalloproteinase-2 (MMP-2). During the sensing process, aggregation of AIE residual could be intensified through the electrostatic absorption by negatively charged nanoparticles (NPs), as well as the confined space formed by the self-assembly of NPs to photonic crystals (PCs) on slippery lubricant-infused porous substrates (SLIPS). The fluorescent signals obviously increased with a strengthened aggregation degree, which contributes to improved sensitivity. Thus, the limit of detection is decreased to 3.7 ng/mL for MP/NPs-SLIPS sensing system, which could be used for detecting the MMP-2 secreted by tumor cells directly. This strategy also demonstrated its potential applications as high-throughput detection devices and will be of significance for the ultrasensitive analysis of biomarkers.

Nanochannel-based fluidic diodes display ion selectivity and ion current rectification (ICR), which may prove to be important in energy-harvesting devices and biosensors. This paper reports asymmetric functionalization of the outer surface of a flexible nanochannel polymer membrane to create fluidic diodes that give ICR. Layer-by-layer (LbL) adsorption with cross-linking of only the underlying part of the polyelectrolyte nanofilm leads to a porosity step across the film. The combination of a high effective surface charge density and the porosity step in the film leads to a remarkable maximum ICR factor of ∼200 with a pH gradient across the film. Incorporation of pH-sensitive polyelectrolyte components enables the ICR factor to increase an order of magnitude on going from pH 8 to pH 3. Moreover, the coated membrane shows excellent anion selectivity. Thus, LbL adsorption with partial cross-linking provides a simple method for creating coated nanochannel membranes that serve as pH-responsive ionic diodes for potential chemical/biosensors.

Electrochemical aptamer-based (E-AB) sensors, exploiting binding-induced changes in biomolecular conformation, are rapid, specific, and selective and perform well even in a complex matrix, such as directly in whole blood and even in vivo. However, like all sensors employing biomolecular recognitions, E-AB sensors suffer from an inherent limitation of single-site binding, i.e., its fixed dose-response curve. To circumvent this, we employ here distal-site mutation and allosteric inhibition to rationally tune the dynamic range of E-AB sensors, achieving sets of sensors with a significantly varied target affinity (∼3 orders of magnitude). Using their combination, we recreate several approaches to narrow (down to 5-fold) or extend (up to 2000-fold) the dynamic range of biological receptors. The thermodynamic consequences of aptamer-surface interactions are estimated via the free-energy difference in solution-phase and surface-bound biosensors employing the same aptamer as a recognition element, revealing that an allostery strategy provides a more predictable and efficient means to finely control the target affinity and dynamic range. Such an ability to rationally modulate the affinity of biomolecule receptors would open the door to applications including cancer therapy, bioelectronics, and many other fields employing biomolecule recognition.

The ability to monitor specific molecules in real-time directly in a flowing sample stream and in a manner that does not adulterate that stream could greatly augment quality control in, for example, food processing and pharmaceutical manufacturing. Because they are continuous, reagentless, and able to work directly in complex samples, electrochemical DNA-based (E-DNA) sensors, a modular and, thus, general sensing platform, are promising candidates to fill this role. In support, we describe here an E-DNA sensor supporting the continuous, real-time measurement of melamine in flowing milk. Using target-driven DNA triplex formation to generate an electrochemical output, the sensor responds to rising and falling melamine concentration in seconds without contaminating the product stream. The continuous, autonomous, real-time operation of sensors such as this could provide unprecedented safety, convenience, and cost-effectiveness relative to the batch processes historically employed in molecular quality control.

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.

Nowadays, the probe with fluorophore but no quencher is promising for its simple preparation, environmental friendliness, and wide application scope. This study designs a new amphiphilic nucleic acid probe (ANAP) based on aggregation-caused quenching (ACQ) effect without any quencher. Upon binding with targets, the dispersion of hydrophobic part (conjugated fluorene, CF) in ANAP is enhanced as a signal-on model for proteins, nucleic acids, and small molecules detection or the aggregation of CF is enhanced as a signal-off model for ion detection. Meanwhile, because of the high specificity of ANAP, a one-step method is developed powerfully for monitoring the telomerase activity not only from the cell extracts but also from 50 clinic urine samples (positive results from 45 patients with bladder cancer and negative results from 5 healthy people). ANAPs can also readily enter into cells and exhibit a good performance for distinguishing natural tumor cells from the tumor cells pretreated by telomerase-related drugs or normal cells. In contrast to our previous results ( Anal. Chem. 2015 , 87 , 3890 - 3894 ), the present CF is a monomer which is just the structure unit of the previous fluorescent polymer. Since the accurate molecular structure and high DNA/CF ratio of the present CF, these advanced experiments obtain an easier preparation of probes, an improved sensitivity and specificity, and broader detectable targets.

In situ detecting and monitoring intracellular telomerase activity is significant for cancer diagnosis. In this work, we report a facile and fast-responsive bioprobe for in situ detection and imaging of intracellular telomerase activity with superior photostability. After transfected into living cells, quencher group labeled TS primer (QP) can be extended in the presence of intracellular telomerase. Positive charged TPE-Py molecules (AIE dye) will bind to the primer as well as extension repeated units, producing a telomerase activity-related turn-on fluorescence signal. By incorporating positive charged AIE dye and substrate oligonucleotides, in situ light-up imaging and detection of intracellular telomerase activity were achieved. This strategy exhibits good performance for sensitive in situ tracking of telomerase activity in living cells. The practicality of this facile and fast-responsive telomerase detection method was demonstrated by using it to distinguish tumor cells from normal cells and to monitor the change of telomerase activity during treatment with antitumor drugs, which shows its potential in clinical diagnostic and therapeutic monitoring.

In recent years, artificial stimuli-responsive bioinspired nanopores have attracted a lot of attention due to their unique property of confined spaces and flexibility in terms of shapes and sizes. Most of the nanopore systems demonstrated their transmembrane properties and applications in target detections. However, almost all of the nanopores can be used only once due to either the irreversible reactions between targets and probes or the plugged nanopores not easily being unplugged again. In this work, we propose a dual-signal-output nanopore system that could detect the cations (Hg(2+)) inducing the plugged nanopores. The detection system is highly recoverable by the anions (S(2-)) inducing the unplugged nanopores. More importantly, as far as we know, it is seldom reported for the same nanopores to achieve successive calibration curves for three times by subsequent reversible plug-unplug processes, which strongly demonstrates the high robustness of this novel nanopore-detection system. In addition, unlike monitoring the plug-unplug phenomena by only one type of signal, we combined the ionic current signal with the fluorescence output and could directly observe that the change of ionic current does in fact correspond to the plug-unplug of the nanopores by the target stimuli.

Detection of an ultralow concentration of mRNA is important in the prognosis of gene-related diseases. In this study, a DNA-conjugated amphiphilic aggregation-induced emission probe (TPE-R-DNA) was synthesized for cancer tissue imaging and prognosis analysis based on an exonuclease III-aided target recycling technique. TPE-R-DNA comprise two components: a hydrophobic component that serves as the “turn-on” long wavelength fluorescence imaging agent (TPE-R-N3); and a hydrophilic single DNA strand (Alk-DNA) which acts as specific recognition part for target mRNA. In the absence of target mRNA, TPE-R-DNA had almost no fluorescence because of its high water solubility. Conversely, the TPE-R-DNA was digested by exonuclease III (Exo III) in the presence of MnSOD mRNA to release the hydrophobic fluorogens (TPE-R-AT). Subsequently, TPE-R-AT formed aggregates, and therefore, fluorescence signal was distinctly observed. For the first time, the structure of the hydrolysis product (TPE-R-AT), containing two bases A an...

Although extensively used in all fields of chemistry, molecular recognition still suffers from a significant limitation: host-guest binding displays a fixed, hyperbolic dose-response curve, which limits its usefulness in many applications. Here we take advantage of the high programmability of DNA chemistry and propose a universal strategy to engineer biorecognition-based sensors with dual programmable dynamic ranges. Using DNA aptamers as our model recognition element and electrochemistry as our readout signal, we first designed a dual signaling "signal-on" and "signal-off" adenosine triphosphate (ATP) sensor composed of a ferrocene-labeled ATP aptamer in complex to a complementary, electrode-bound, methylene-blue labeled DNA. Using this simple "dimeric" sensor, we show that we can easily (1) tune the dynamic range of this dual-signaling sensor through base mutations on the electrode-bound DNA, (2) extend the dynamic range of this sensor by 2 orders of magnitude by using a combination of electrode-bound strands with varying affinity for the aptamers, (3) create an ultrasensitive dual signaling sensor by employing a sequestration strategy in which a nonsignaling, high affinity "depletant" DNA aptamer is added to the sensor surface, and (4) engineer a sensor that simultaneously provides extended and ultrasensitive readouts. These strategies, applicable to a wide range of biosensors and chemical systems, should broaden the application of molecular recognition in various fields of chemistry.

Telomerase is a widely used tumor biomarker for early cancer diagnosis. On the basis of the combined use of aggregation-induced emission (AIE) fluorogens and quencher, a quencher group induced high specificity strategy for detection of telomerase activity from cell extracts and cancer patients' urine specimens was creatively developed. In the absence of telomerase, fluorescence background is extremely low due to the short distance between quencher and AIE dye. In the addition of telomerase, fluorescence enhances significantly. The telomerase activity in the E-J, MCF-7, and HeLa extracts equivalent to 5-10 000 cells can be detected by this method in ∼1 h. Furthermore, the distinguishing of telomerase extracted from 38 cancer and 15 normal urine specimens confirms the reliability and practicality of this protocol. In contrast to our previous results (Anal. Chem. 2015, 87, 6822-6827), these advanced experiments obtain more remarkable specificity.

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.

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.

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.

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.

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.