In Situ Visualization of RNA-Specific Sialylation on Living Cell Membranes to Explore N-Glycosylation Sites.

The small RNAs on living cell membranes were recently found to be N-glycosylated and terminated with sialic acids, although the glycosylation sites and potential functions remain unclear. Herein, we designed a second-generation hierarchical coding strategy (HieCo 2) for in situ visualization of cell surface RNA-specific sialylation. After covalently binding DNA codes to sialic acids and then binding a DNA code to a target RNA via sequence specificity, cascade decoding processes were performed with subsequent signal amplification that enabled sensitive in situ visualization of low-abundance Y5 RNA-specific sialic acids on living cell membranes. The proposed strategy unveils the number of glycosylation sites on a single RNA and reveals the binding preference of glycosylated RNAs to different sialic acid binding-immunoglobulin lectin-type receptors, demonstrating a new route for exploration of the glycosylated RNA-related biological and pathological processes.

Reticular Ratchets for Directing Electrochemiluminescence.

Electrochemiluminescence (ECL) involves charge transfer between electrochemical redox intermediates to produce an excited state for light emission. Ensuring precise control of charge transfer is essential for decoding ECL fundamentals, yet guidelines on how to achieve this for conventional emitters remain unexplored. Molecular ratchets offer a potential solution, as they enable the directional transfer of energy or chemicals while impeding the reverse movement. Herein, we designed 10 pairs of imine-based covalent organic frameworks as reticular ratchets to delicately manipulate the intrareticular charge transfer for directing ECL transduction from electric and chemical energies. Aligning the donor and acceptor (D-A) directions with the imine dipole effectively facilitates charge migration, whereas reversing the D-A direction impedes it. Notably, the ratchet effect of charge transfer directionality intensified with increasing D-A contrast, resulting in a remarkable 680-fold improvement in the ECL efficiency. Furthermore, dipole-controlled exciton binding energy, electron/hole decay kinetics, and femtosecond transient absorption spectra identified the electron transfer tendency from the N-end toward the C-end of reticular ratchets during ECL transduction. An exponential correlation between the ECL efficiency and the dipole difference was discovered. Our work provides a general approach to manipulate charge transfer and design next-generation electrochemical devices.

Coupled Poly(ethylenimine) Coreactant to Enhance Electrochemiluminescence of Polymer Dots for Array Imaging of Protein Biomarkers.

Traditional electrochemiluminescent (ECL) bioanalysis suffers from the demand for excessive external coreactants and the damage of reaction intermediates. In this work, a poly(ethylenimine) (PEI)-coupled ECL emitter was proposed by covalently coupling tertiary amine-rich PEI to polymer dots (Pdots). The coupled PEI might act as a highly efficient coreactant to enhance the ECL emission of Pdots through intramolecular electron transfer, reducing the electron transfer distance between emitter and coreactant intermediates and avoiding the disadvantages of traditional ECL systems. Through modification of the PEI-Pdots with tDNA, a sequence partially complementary to cDNA that was complementary to the aptamer of target protein biomarker (aDNA), tDNA-PEI-Pdots were obtained. The biosensors were produced using Au/indium tin oxide (ITO) with an aDNA/cDNA hybrid, and an ECL imaging biosensor array was constructed for ultrasensitive detection of protein biomarkers. Using vascular endothelial growth factor 165 (VEGF165) as a protein model, the proposed ECL imaging method containing two simple incubations with target samples and then tDNA-PEI-Pdots showed a detectable range of 1 pg mL-1 to 100 ng mL-1 and a detection limit of 0.71 pg mL-1, as well as excellent performance such as low toxicity, high sensitivity, excellent selectivity, good accuracy, and acceptable fabrication reproducibility. The PEI-coupled Pdots provide a new avenue for the design of ECL emitters and the application of ECL imaging in disease biomarker detection.

Self-Assembly-Induced Enhancement of Cathodic Electrochemiluminescence of Copper Nanoclusters for a Split-Type Matrix Metalloproteinase 14 Sensing Platform.

The unique optoelectronic and tunable luminescent characteristics of copper nanoclusters (Cu NCs) make them extremely promising as luminophores. However, the limited luminescence intensity and stability of Cu NCs have restricted their application in the field of electrochemiluminescence (ECL). Herein, a self-assembly-induced enhancement strategy was successfully employed to enhance the cathodic ECL performance of flexible ligand-stabilized Cu NCs. Specifically, Cu NCs form ordered sheetlike structures through intermolecular force. The restriction of ligand torsion in this self-assembled structure leads to a significant improvement in the ECL properties of the Cu NCs. Experimental results demonstrate that the assembled nanoscale Cu NC sheets exhibit an approximately three-fold increase in cathodic ECL emission compared to the dispersed state of Cu NCs. Furthermore, assembled nanoscale Cu NCs sheets were utilized as signal probes in conjunction with a specific short peptide derived from the catalytic structural domain of matrix metalloproteinase 14 (MMP 14) as the identification probe, thereby establishing a split-type ECL sensing platform for the quantification of NMP 14. The investigation has revealed the exceptional performance of assembled nanoscale Cu NCs sheets in ECL analysis, thus positioning them as novel and promising signal probes with significant potential in the field of sensing.

Highly Electroactive Co2+-Based Metal-Organic Frameworks as an Efficient Coreaction Accelerator for Amplifying Near-Infrared Electrochemiluminescence of Gold Nanoclusters in Biomarkers Immunoassay.

Metal nanoclusters (NCs) as a new kind of luminophore have acquired sufficient interest, but their widespread application is restricted on account of their relatively low electrochemiluminescence (ECL) efficiency. Then, aqueous metal NCs with high ECL efficiency were strongly anticipated, especially for the ultrasensitive analysis of biomarkers. Herein, a near-infrared (NIR) ECL biosensing strategy for the test of neuron-specific enolase (NSE) was proposed by utilizing N-acetyl-l-cysteine (NAC)- and cysteamine (Cys)-stabilized gold NCs (NAC/Cys-AuNCs) as ECL emitters with the NIR ECL emission around 860 nm and a metal-organic framework/palladium nanocubes (ZIF-67/PdNCs) hybrid as the coreaction accelerator through their admirable electrocatalytic activity. The NIR emission would reduce photochemical injury to the samples and even realize nondestructive analysis with highly strong susceptibility and suitability. Furthermore, the utilization of ZIF-67/PdNCs could improve the ECL response of NAC/Cys-AuNCs by facilitating the oxidation of the coreactant triethylamine (TEA), leading to the production of a larger quantity of reducing intermediate radical TEA•+. Consequently, NAC/Cys-AuNCs with ZIF-67/PdNCs displayed 2.7 fold enhanced ECL emission compared with the single NAC/Cys-AuNCs using TEA as the coreactant. In addition, HWRGWVC (HWR), a heptapeptide, was introduced to immobilize antibodies for the specially binding Fc fragment of the antibodies, which improved the binding efficiency and sensitivity. As a result, a "signal-on" immunosensor for NSE analysis was obtained with an extensive linear range of 0.1 to 5 ng/mL and a low limit of detection (0.033 fg/mL) (S/N = 3). This study provides a wonderful method for the development of an efficient nondestructive immunoassay.

Ligation-Based High-Performance Mimetic Enzyme Sensing Platform for Nucleic Acid Detection.

G-quadruplex (G4)/hemin DNAzyme is a promising candidate to substitute horseradish peroxidase in biosensing systems, especially for the detection of nucleic acids. However, the relatively suboptimal catalytic capacity limits its potential applications. This makes it imperative to develop an ideal signal for the construction of highly sensitive biosensing platforms. Herein, we integrated a novel chimeric peptide-DNAzyme (CPDzyme) with the ligase chain reaction (LCR) for the cost-efficient and highly sensitive detection of nucleic acids. By employing microRNA (miRNA) and single-nucleotide polymorphism detection as the model, we designed a G4-forming sequence on the LCR probe with a terminally labeled amino group. Subsequently, asymmetric hemin with carboxylic arms allowed assembly with the LCR products and peptide to form CPDzyme, followed by the magnetic separation of the extraneous components and chemiluminescence detection. Compared with the conventional G4/hemin signaling-based method, the LCR-CPDzyme system demonstrated 3 orders of magnitude improved sensitivity, with accurate quantification of as low as 25 aM miRNA and differentiation of 0.1% of mutant DNA from the pool containing a large amount of wild-type DNA. The proposed LCR-CPDzyme strategy is a potentially powerful method for in vitro diagnostics and serves as a reference for the development of other ligation- or hybridization-based nucleic acid amplification assays.

Multifunctional Supramolecular Hydrogel Modulated Heterojunction Interface Carrier Transport Engineering Facilitates Sensitive Photoelectrochemical Immunosensing.

Highly responsive interface of semiconductor nanophotoelectrochemical materials provides a broad development prospect for the identification of low-abundance cancer marker molecules. This work innovatively proposes an efficient blank WO3/SnIn4S8 heterojunction interface formed by self-assembly on the working electrode for interface regulation and photoregulation. Different from the traditional biomolecular layered interface, a hydrogel layer containing manganese dioxide with a wide light absorption range is formed at the interface after an accurate response to external immune recognition. The formation of the hydrogel layer hinders the effective contact between the heterojunction interface and the electrolyte solution, and manganese dioxide in the hydrogel layer forms a strong competition between the light source and the substrate photoelectric material. The process effectively improves the carrier recombination efficiency at the interface, reduces the interface reaction kinetics and photoelectric conversion efficiency, and thus provides strong support for target identification. Taking advantage of the process, the resulting biosensors are being explored for sensitive detection of human epidermal growth factor receptor 2, with a limit of detection as low as 0.037 pg/mL. Also, this study contributes to the advancement of photoelectrochemical biosensing technology and opens up new avenues for the development of sensitive and accurate analytical tools in the field of bioanalysis.

Photocleavable DNA Nanotube-Based Dual-Amplified Resonance Rayleigh Scattering System for MicroRNA Detection Incorporating Molecular Computing-Cascaded Keypad Lock Functionality.

Cascade molecular events in complex systems are of vital importance for enhancing molecular diagnosis and information processing. However, the conversion of a cascaded biosensing system into a multilayer encrypted molecular keypad lock remains a significant challenge in the development of molecular logic devices. In this study, we present a photocleavable DNA nanotube-based dual-amplified resonance Rayleigh scattering (RRS) system for detecting microRNA-126 (miR-126). The cascading dual-amplification biosensing system provides a multilayer-encrypted prototype with the functionality of a molecular computing cascade keypad lock. RRS signals were greatly amplified by using photocleavable DNA nanotubes and enzyme-assisted strand displacement amplification (SDA). In the presence of miR-126, enzyme-assisted SDA produced numerous identical nucleotide fragments as the target, which were then specifically attached to magnetic beads through the DNA nanotube by using a Y-shaped DNA scaffold. Upon ultraviolet irradiation, the DNA nanotube was released into the solution, resulting in an increase in the intensity of the RRS signal. This strategy demonstrated a low limit of detection (0.16 fM) and a wide dynamic range (1 fM to 1 nM) for miR-126. Impressively, the enzyme-assisted SDA offers a molecular computing model for generating the target pool, which serves as the input element for unlocking the system. By cascading the molecular computing process, we successfully constructed a molecular keypad lock with a multilevel authentication technique. The proposed system holds great potential for applications in molecular diagnosis and information security, indicating significant value in integrating molecular circuits for intelligent sensing.

Securing LYTAC with Logic-Identification System for Cancer Cell-Selective Membrane Protein Degradation.

Lysosome-targeting chimera (LYTAC) links proteins of interest (POIs) with lysosome-targeting receptors (LTRs) to achieve membrane protein degradation, which is becoming a promising therapeutic modality. However, cancer cell-selective membrane protein degradation remains a big challenge considering expressions of POIs in both cancer cells and normal cells, as well as broad tissue distribution of LTRs. Here a logic-identification system is designed, termed Logic-TAC, based on cell membrane-guided DNA calculations to secure LYTAC selectively for cancer cells. Logic-TAC is designed as a duplex DNA structure, with both POI and LTR recognition regions sealed to avoid systematic toxicity during administration. MCF-7 and MCF-10A are chosen as sample cancer cell and normal cell respectively. As input 1 for logic-identification, membrane proteins EpCAM, which is highly expressed by MCF-7 but barely by MCF-10A, reacts with Logic-TAC to expose POI recognition region. As input 2 for logic-identification, Logic-TAC binds to POI, membrane protein MUC1, to expose LTR recognition region. As output, MUC1 is connected to LTR and degraded via lysosome pathway selectively for cancer cell MCF-7 with little side effect on normal cell MCF-10A. The logic-identification system also demonstrated satisfactory in vivo therapeutic results, indicating its promising potential in precise targeted therapy.

Reticular Electrochemiluminescence Nanoemitters: Structural Design and Enhancement Mechanism.

ConspectusElectrochemiluminescence (ECL) is a powerful transduction technique, which depends critically on the formation of the excited emitter through the charge transfer between the electrochemical reaction intermediates of the emitter and the co-reactant/emitter. The exploration of ECL mechanisms for conventional nanoemitters is limited due to the uncontrollable charge transfer process. With the development of molecular nanocrystals, reticular structures such as metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) have been utilized as atomically precise semiconducting materials. The long-range order in crystalline frameworks and the tunable coupling among building blocks promote the quick development of electrically conductive frameworks. Especially, the reticular charge transfer can be regulated by both interlayer electron coupling and intralayer topology-templated conjugation. By modulating intramolecular or intermolecular charge mobility, reticular structures could serve as promising candidates for enhancing ECL. Thus, reticular crystalline nanoemitters with different topologies provide a confined platform to understand ECL fundamentals for designing next-generation ECL devices.Aiming at exploring the mechanism of ECL emission, our group has developed a series of ECL nanoemitters as well as enhancement strategies of ECL emission in the past 20 years. A series of water-soluble ligand-capped quantum dots were introduced as ECL nanoemitters to create sensitive analytical methods for detecting and tracing biomarkers. The functionalized polymer dots were also designed as ECL nanoemitters for imaging of membrane proteins with signal transduction strategies of dual resonance energy transfer and dual intramolecular electron transfer. To decode the ECL fundamental and enhancement mechanisms, an electroactive MOF with accurate molecular structure was first constructed with two redox ligands as a highly crystallized ECL nanoemitter in aqueous medium. Through the mixed-ligand approach, luminophores and co-reactants were integrated into one MOF structure for self-enhanced ECL. Furthermore, several donor-acceptor COFs were developed as efficient ECL nanoemitters with tunable intrareticular charge transfer. The atomically precise structure of conductive frameworks established clear correlations between the structure and charge transport in these materials. Therefore, reticular materials as crystalline ECL nanoemitters have demonstrated both proof of concept and mechanistic innovation.In this Account, taking advantage of reticular materials with accurate molecular structure, we survey the design of the electroactive reticular materials including MOFs and COFs as crystalline ECL nanoemitters at the molecular level. The enhancement mechanisms of ECL emission of various topology frameworks are discussed via the regulation of reticular energy transfer and charge transfer and the accumulation of anion/cation radicals. Our perspective on the reticular ECL nanoemitters is also discussed. This Account provides a new avenue for designing molecular crystalline ECL nanoemitters and decoding the fundamentals of ECL detection methods.

A photoelectrochemical aptasensing platform assembled at the heterojunction interface of Cu3BiS3 sensitized CuV2O6 for bisphenol A.

The interaction between the sensitive interfaces of photoelectrochemical (PEC) semiconductor nanomaterials and microscopic matter creates endless potential for the efficient detection of endocrine disruptor. This work presents the development of a high-efficiency PEC aptasensor for bisphenol A (BPA) monitoring based on Cu3BiS3 sensitized CuV2O6 nanocomposites with exceptional visible-light PEC activity. We implemented the integration of Cu3BiS3 nanosheet photosensitizer to sensitize the CuV2O6 nanowire structure that was synthesized utilizing a facile hydrothermal approach. The band gap alignment between Cu3BiS3 and CuV2O6 facilitated enduring PEC response yielding an efficient interfacial structure. The surface of the CuV2O6/Cu3BiS3 electrode was modified with BPA aptamer, enabling specific binding with BPA and precise quantification of its content. The developed aptamer sensors possess a wide detection range of 5.00 × 10-1 to 5.00 × 104 ng/mL, and a low detection limit of 1.60 × 10-1 ng/mL (at S/N = 3). After undergoing 20 testing cycles and enduring long-term storage, the sensor maintained its stability and showcased excellent repeatability and reproducibility. This study presents a promising methodology for the detection of BPA in environmental settings.

Cancer Cell-Selective PD-L1 Inhibition via a DNA Safety Catch to Enhance Immunotherapy Specificity.

Immune checkpoint protein blockade (ICB) has emerged as a powerful immunotherapy approach, but suppressing immune-related adverse events (irAEs) for noncancerous cells and normal tissues remains challenging. Activatable ICB has been developed with tumor microenvironment highly-expressed molecules as stimuli, but they still lack precision and efficiency considering the diffusion of stimuli molecules in whole tumor tissue. Here we assemble PD-L1 with a duplex DNA strand, termed as "safety catch", to regulate its accessibility for ICB. The safety catch remains at "on" status for noncancerous cells to prevent ICB binding to PD-L1. Cancer cell membrane protein c-Met acts as a trigger protein to react with safety catch, which selectively exposes its hybridization region for ICB reagent. The ICB reagent is a retractable DNA nanostring with repeating hairpin-structural units, whose contraction drives PD-L1 clustering with endocytosis-guided degradation. The safety catch, even remained at "safety on" status, is removed from the cell membrane via a DNA strand displacement reaction to minimize its influence on noncancerous cells. This strategy demonstrates selective and potent immunotherapeutic capabilities only against cancer cells both in vitro and in vivo, and shows effective suppression of irAEs in normal tissues, therefore would become a promising approach for precise immunotherapy in mice.

Ultra-Galactocation to Sialic Acid on Tumor Cells with A Penta-Functional Dendritic Probe for Enhanced Immune-Killing.

Glycans on tumor cell surface have significant impacts in the immune-killing process. Here an ultra-galactocation to sialic acid (Sia) strategy is designed to hugely introduce galactose (Gal) to Sia and on tumor cells in vivo by using a penta-functional dendritic probe (Den@5F), which efficiently enhances the immune-killing of tumor cells. The Den@5F contains five different kinds of functional groups, including Gal, Cy5, amino, phenylboronic acid (PBA) and 4-(4-(hydroxymethyl)-2-methoxy-5-nitrophenoxy) butanoate (mNB), which can be conveniently prepared through a two-step reaction. After injecting into the tumor-bearing mouse, Den@5F can efficiently block Sia through the specific recognition between PBA and Sia on tumor cells and hugely introduce Gal through the subsequent photo-crosslinking between mNB and amino groups to multiply conjugate excessive Den@5Fs. The comprehensively blocked Sia can prevent the immune escape, and the hugely introduced Gal can promote the immune stimulation of the immune cells, which lead to an efficient enhancement of the immune-killing. The proposed strategy provides a significant and promising tool to promote the clinical immunotherapy of tumor.

An In-Situ-Tag-Generation Proximity Labeling Technology for Recording Cellular Interactions.

Obtaining information about cellular interactions is fundamental to the elucidation of physiological and pathological processes. Proximity labeling technologies have been widely used to report cellular interactions in situ; however, the reliance on addition of tag molecules typically restricts their application to regions where tags can readily diffuse, while the application in, for example, solid tissues, is susceptible. Here, we propose an "in-situ-tag-generation mechanism" and develop the GalTag technology based on galactose oxidase (GAO) for recording cellular interactions within three-dimensional biological solid regions. GAO mounted on bait cells can in situ generate bio-orthogonal aldehyde tags as interaction reporters on prey cells. Using GalTag, we monitored the dynamics of cellular interactions and assessed the targeting ability of engineered cells. In particular, we recorded, for the first time, the footprints of Bacillus Calmette-Guérin (BCG) invasion into the bladder tissue of living mice, providing a valuable perspective to elucidate the anti-tumor mechanism of BCG.

Cancer Cell-Selective Membrane Receptor Clustering Driven by VEGF Secretion for In Vivo Therapy.

Clustering of cell membrane receptors regulates cell behaviors. Although receptor clustering plans have achieved wide applications in cancer therapy, it still remains challenging to manipulate receptor clustering selectively for cancer cells with little influence on normal cells. Here, we design a Raji cell Selective MAnipulation of Receptor Clustering (SMARC) strategy for CD20, which is driven by endogenous secretion of Raji cells. Retractable DNA nanostrings with repeating hairpin-structured units are anchored to the cell membrane CD20, which contract in response to Raji cell-secreted vascular endothelial growth factor (VEGF) with corresponding CD20 clustering. The contraction of DNA nanostrings is intensified via a VEGF amplifier including DNA cyclic reactions to continuously trigger the foldings of hairpin-structured units in DNA nanostrings. The SMARC strategy shows selective and efficient apoptosis of Raji cells with little interference to normal B cells and demonstrates good in vivo therapeutic efficacy, which provides a promising tool for precise cancer therapy.

Cell-Selective Multifunctional Surface Covalent Reconfiguration Using Aptamer-Enabled Proximity Catalytic Labeling.

Cell surface engineering provides access to custom-made cell interfaces with desirable properties and functions. However, cell-selective covalent labeling methods that can simultaneously install multiple molecules with different functions are scarce. Herein, we report an aptamer-enabled proximity catalytic covalent labeling platform for multifunctional surface reconfiguration of target cells in mixed cell populations. By conjugating peroxidase with cell-selective aptamers, the probes formed can selectively bind target cells and catalyze target-cell-localized covalent labeling in situ. The universal applicability of the platform to different phenol-modified functional molecules allows us to perform a variety of manipulations on target cells, including labeling, tracking, assembly regulation, and surface remodeling. In particular, the platform has the ability of multiplexed covalent labeling, which can be used to install two mutually orthogonal click reactive molecules simultaneously on the surface of target cells. We thus achieve "multitasking" in complex multicellular systems: programming and tracking specific cell-cell interactions. We further extend the functional molecules to carbohydrates and perform ultrafast neoglycosylation on target living cells. These newly introduced sugars on the cell membrane can be recognized and remodeled by a glycan-modifying enzyme, thus providing a method package for cell-selective engineering of the glycocalyx.

Chimeric Biocatalyst Combining Peptidic and Nucleic Acid Components Overcomes the Performance and Limitations of the Native Horseradish Peroxidase.

Chimeric peptide-DNAzyme (CPDzyme) is a novel artificial peroxidase that relies on the covalent assembly of DNA, peptides, and an enzyme cofactor in a single scaffold. An accurate control of the assembly of these different partners allows for the design of the CPDzyme prototype G4-Hemin-KHRRH, found to be >2000-fold more active (in terms of conversion number kcat) than the corresponding but non-covalent G4/Hemin complex and, more importantly, >1.5-fold more active than the corresponding native peroxidase (horseradish peroxidase) when considering a single catalytic center. This unique performance originates in a series of gradual improvements, thanks to an accurate selection and arrangement of the different components of the CPDzyme, in order to benefit from synergistic interactions between them. The optimized prototype G4-Hemin-KHRRH is efficient and robust as it can be used under a wide range of non-physiologically relevant conditions [organic solvents, high temperature (95 °C), and in a wide range of pH (from 2 to 10)], thus compensating for the shortcomings of the natural enzymes. Our approach thus opens broad prospects for the design of ever more efficient artificial enzymes.

Regulation of Target-activated CRISPR/Cas12a on Surface Binding of Polymer Dots for Sensitive Electrochemiluminescence DNA Analysis.

Polymer dots (Pdots) have emerged as a type of attractive electrochemiluminescence (ECL) emitter. However, the low ECL efficiency severely limits their practicability. In this work, we develop a sensitive ECL biosensing strategy for the detection of human papilloma virus subtype (HPV-16) DNA by using target-activated CRISPR/Cas12a to regulate the binding of Pdots-DNA to biosensor and local surface plasmon resonance (LSPR) effect of electrochemically deposited Au nanoparticles (depAuNPs) to enhance the ECL emission of Pdots bound on biosensor. The biosensor is prepared by simply assembling hairpin DNA on depAuNPs modified electrode. In the presence of target DNA, the designed specific CRISPR/Cas12a can be activated to digest single-stranded assistant DNA, which decreases the amount of hairpin DNA opened by assistant DNA to bind Pdots-DNA on the biosensor surface, thus reduces the ECL emission. The integration of target DNA-triggered catalysis and the LSPR effect of depAuNPs greatly improves the sensitivity of ECL analysis. Using HPV-16 DNA as a target model, the proposed method shows a limit of detection (LOD) of 3.2 fM at a signal-to-noise ratio of 3 and a detectable concentration range of 5.0 fM to 50 pM. The high sensitivity, excellent selectivity, good testing stability, and acceptable fabrication reproducibility of the designed ECL biosensing strategy demonstrate its potential application in DNA bioanalysis.

Electrochemiluminescence Imaging at a Single Nanoparticle Scale to Elucidate Diffusion-Accelerated Charge Transfer and Monitor Cell Permeability.

Accelerating the charge transfer between electroactive species and the electrode is always a hot topic. Here, we report a finding of Ru(bpy)33+ diffusion-induced acceleration of charge transfer from Ru(bpy)32+-doped silica nanoparticles (RDSNs) to the electrode via electrochemiluminescence (ECL) imaging at a single nanoparticle scale. Ru(bpy)32+ in the electrolyte can act as an enhancer of RDSN ECL emission in the presence of coreactant tripropylamine, which amplifies the RDSN ECL by 478 times at 10 µM free Ru(bpy)32+. According to percolation theory, the diffusion of electro-generated Ru(bpy)33+ near a single RDSN brings much quicker charge transfer to the electrode than electron hopping in RDSN, which is demonstrated by spatial and temporal interaction imaging of the RDSN and the Ru(III) diffusion layer. Taking advantage of this new mechanism, a real-time ECL imaging method has been constructed to monitor the rapid change of cell permeability during surfactant treatment.

DNAzyme-Powered DNA Walker for Cooperative Expression Imaging of Mutant p53 and Telomerase in Cancer Cells.

Cooperative expression of multiple cancer biomarkers is of great significance in influencing cell pathways and drug treatment. However, the simultaneous analysis of low-abundance biomarkers in living cells remains a challenge. Here, we report a DNAzyme-powered DNA walker to visualize the cooperative expression of mutant p53 and telomerase in living cells. The activation of the DNA walker is orthogonally powered by mutated p53 and telomerase, which enables the unlocking of the walking strand and the subsequently repeated substrate cleavage, producing fluorescence recovery for the imaging of the two target molecules in living cells. The DNA walker allows for real-time monitoring of the expression profile of mutant p53 and active telomerase in cancer cells under various antitumor drug treatments, and the results demonstrate the cooperative expression of mutant p53 and telomerase via the Akt pathway, which may bring new insights into the study of cancer pathway-relevant biomarkers.