Integrating Reliable Pt-S Bond-Mediated 3D DNA Nanomachine with Magnetic Separation in a Homogeneous Electrochemical Strategy for Exosomal MicroRNA Detection with Low Background and High Sensitivity

Enhanced luminol electrochemiluminescence biosensing system based on highly dispersed bimetallic nanozyme coreaction accelerator and 3D DNA walker signal amplifier

In this work, a platinum-nickel based nanozyme is prepared and used as a coreaction accelerator in the luminol-H2O2 electrochemiluminescence (ECL) system to construct an ECL biosensor for dimethyl phthalate (DMP) detection. The PtNi/NC nanozyme possesses dispersed metal active sites, and the synergistic effect of Pt and Ni endows it with excellent catalytic performance, which effectively converts H2O2 into more superoxide anions, and then significantly enhances the ECL intensity of the luminol system. The ECL mechanism is investigated by combining cyclic voltammetry and ECL with different types of free radical scavengers. Simultaneously, an "off-on" biosensor is constructed by integrating 3D DNA walker with enzyme-free recycling amplification for ultrasensitive detection of DMP. The biosensor based on PtNi/NC nanozyme mediated luminol-H2O2 system and 3D DNA walker exhibits a linear range of 1 × 10-16 to 1 × 10-6 M with a detection limit of 4.3 × 10-17 M (S/N = 3), and displays good stability and specificity. This study demonstrates the advantages of PtNi/NC nanozyme in enhancing the luminol-H2O2 ECL system, providing new strategy for designing efficient ECL emitter and offering a new method for detecting phthalate esters.

Combining hybrid cell membrane modified magnetic nanoparticles and inverted microfluidic chip for in situ CTCs capture and inactivation

Circulating tumor cells (CTCs) serve as crucial indicators for tumor occurrence, progression, and prognosis monitoring. However, achieving high sensitivity and high purity capture of CTCs remains challenging. Additionally, in situ capture and synchronous clearance hold promise as methods to impede tumor metastasis, but further exploration is needed. In this study, biomimetic cell membrane-coated magnetic nanoparticles (NPs) were designed to address the issue of nonspecific adsorption of capture probes by the immune system during blood circulation. Membranes from human breast cancer cells (tumor cell membranes, TMs) and leukocytes (white blood cell membranes, WMs) were extracted and fused to form a hybrid membrane (HM), which was further modified onto the surface of porous magnetic NPs loaded with indocyanine green (ICG). The incorporation of TM enhanced the material's target specificity, thus increasing capture efficiency, while WM coating reduced interference from homologous white blood cells (WBCs), further enhancing capture purity. Additionally, in conjunction with our novel inverted microfluidic chip, this work introduces the first use of polymer photonic crystals as the capture interface for CTCs. Besides providing an advantageous surface structure for CTC attachment, the 808 nm photonic bandgap effectively amplifies the 808 nm excitation light at the capture surface position. Therefore, upon capturing CTCs, the ICG molecules in the probes facilitate enhanced photothermal (PTT) and photodynamic (PDT) synergistic effects, directly inactivating the captured CTCs. This method achieves capture efficiency and purity exceeding 95% and permits in situ inactivation post-capture, providing an important approach for future research on impeding tumor metastasis in vivo.

An advanced 3D DNA nanoplatform for spatiotemporally confined enhanced dual-mode biosensing MicroRNA in cancer cell

Dual-mode signal output platforms have demonstrated considerable promise due to their improved anti-interference capability and inherent signal self-correction. Nevertheless, traditional discrete-distributed signal probes often encounter significant drawbacks, including limited mass transfer efficiency, diminished signal strength, and instability in intricate biochemical environments. In response to these challenges, a scalable and hyper-compacted 3D DNA nanoplatform resembling "periodic focusing heliostat" has been developed for synergistically enhanced fluorescence (FL) and surface-enhanced Raman spectroscopy (SERS) biosensing of miRNA in cancer cells. Our approach utilized a distinctive assembly strategy integrating gold nanostars (GNS) as fundamental "heliostat units" linked by palindromic DNA sequences to facilitate each other hand-in-hand cascade alignment and condensed into large scale nanostructures. This configuration was further augmented by the incorporation of gold nanoparticles (GNP) via strong Au-S bonds, resulting in a sturdy framework for improved signal transduction. The initiation of this assembly process was mediated by the hybridization of dsDNA to miRNA-21, which served as a primer for polymerization and nicking reactions, thus generating a multifunctional T2 probe. This probe is intricately designed with three distinct parts: a 3'-palindromic end for structural integrity, a central region for capturing SERS-active probes (Cy3-P2), and a 5'-segment for attaching fluorescence reporters. Upon integration T2 into the GNS-based heliostat unit, it promotes palindromic arm-induced aggregation and plasma exciton coupling between plasma nanoparticles and signal transduction tags. This clustered arrangement creates a high-density "hot spot" array that maximizes the local electromagnetic fields necessary for enhanced SERS and FL response. This superstructure supports enhanced aggregation-induced signal amplification for both SERS and FL, offering exceptional sensitivity with LOD as low as 0.0306 pM and 0.409 pM. The efficacy of this method was demonstrated in the evaluation of miRNA-21 in various cancer cell lines.

Target-induced multiregion MNAzyme nanowires for ultrasensitive homogeneous detection of microRNAs

A target-induced multiregion MNAzyme nanowire system is designed for the ultrasensitive and homogeneous detection of microRNAs (miRNAs). miRNA-21 and miRNA-375 are chosen as analytes, and a miRNA-induced primer exchange reaction (PER) is utilized to construct a long DNA strand with repetitive sequences. This innovative design enables the efficient anchoring of numerous MNAzymes. This unique architecture significantly boosts the effective local concentration of MNAzymes, thereby enhancing the sensitivity and efficiency of miRNA detection. Notably, the limit of detection (LOD) achieved with our target-induced multiregion MNAzyme nanowire approach is over an order of magnitude lower than most other MNAzyme-based methods, while the MNAzyme reaction time is reduced from several hours to 50 min. The method has demonstrated successful applications in quantitatively determining the expression levels of two miRNAs in cell lysates of MCF-7, HeLa and MCF-10 A cells, highlighting its potential for assaying miRNA biomarkers in clinical samples.

A recognition-induced three-dimensional bipedal DNA walker for highly sensitive detection of APE1

In contrast to the unipedal DNA walker, a bipedal DNA walker features a broader walking area and exhibits faster walking kinetics, leading to enhanced amplification efficiency. In this study, we designed a stochastic three-dimensional (3D) bipedal DNA walker, capable of navigating AuNP-based 3D tracks, driven by exonuclease III (Exo III). This detection system enables the linear detection of the non-invasive biomarker apurinic/apyrimidinic endonuclease 1 (APE1) activity across a range of 0 to 120 U per mL, with a detection limit of 0.03 U per mL. The platform not only offers a novel DNA walker for sensitive APE1 detection in cell lysate but also facilitates the precise assessment of NCA's inhibitory effect on APE1. This research holds promise for future screening of other potential APE1 inhibitors.

Stochastic bipedal dual-DNA walkers for fast and sensitive detection of apurinic/apyrimidinic endonuclease1 and inhibitor screening

DNA walkers have emerged as a powerful tool in various biosensors, enabling the detection of low-abundance analytes with their precise programmability and efficient signal amplification capacity. However, many existing approaches are hampered by limited reaction kinetics. Herein, we designed a stochastic bipedal dual-DNA walkers (SBDW) that can traverse at high speed on AuNP-based three-dimensional (3D) tracks powered by Exo III. The SBDW exhibited superior reaction kinetics and are up to least 2.25 times faster than traditional DNA walkers, reaching a plateau within 40 min. This advancement allows for rapid and highly sensitive fluorescence detection of a significant base excision repair enzyme of APE1 with a detection limit of 0.001 U/mL. In comparison to traditional DNA walkers, this platform enables highly sensitive and specific APE1 assays in cell lysate and facilitates rapid and accurate screening of APE1 inhibitors. Given its rapid, sensitive, specific, and reliable analysis features, the strategy shows great promise in drug discovery and clinical diagnosis.

Ultrasensitive detection of the H5N1 nucleic acid fragment by ICP-MS using DNA dendrimer-carried silver nanoparticle labeling

The importance of avian influenza virus (AIV) detection in clinical diagnosis and prognosis has been deeply recognized. In this study, the ultrasensitive detection of AIV subtype H5N1 was achieved by ICP-MS combined with DNA dendrimer-carried silver nanoparticle (AgNP) labeling. First, a magnetic control system was constructed by anchoring double-strand DNAs (dsDNAs) which contained a complementary sequence of H5N1 and two locked triggers on the surface of magnetic beads (MBs). When H5N1 was present, the two triggers were released and initiated dendrimer hybridization chain reactions which led to the generation of DNA dendrimer-carried AgNPs on the surface of the MBs. Finally, the AgNPs were collected via magnetic separation, digested by nitric acid, and tested using ICP-MS. The signal intensities of 107Ag were positively correlated with the concentrations of H5N1. Notably, the DNA dendrimer assembly contributed to significant signal amplification and good sensitivity with the limit of detection as low as 2.0 × 10-11 mol L-1. Moreover, the method displayed favorable selectivity against mismatched H5N1 and good recoveries in human serum samples. It is a promising analytical tool for the H5N1 virus and other subtypes of AIV, and has potential value in clinical diagnosis and prognosis of infectious diseases.

A DNA walker based on hairpin-shaped DNA aligner and fueled by nicking endonuclease for sensitive and rapid miRNA analysis

BACKGROUND

DNA walker-based strategies have gained significant attention in nucleic acid analysis. However, they face challenges related to balancing design complexity, sequence dependence, and amplification efficiency. Furthermore, most existing DNA walkers rely on walking and lock probes, requiring optimization of various parameters like DNA probe sequence, walking-to-lock probe ratio, lock probe length, etc. to achieve optimal performance. This optimization process is time-consuming and adds complexity to experiments. To enhance the performance and reliability of DNA walker nanomachines, there is a need for a simpler, highly sensitive, and selective alternative strategy.

RESULTS

A sensitive and rapid miRNA analysis strategy named hairpin-shaped DNA aligner and nicking endonuclease-fueled DNA walker (HDA-NE DNA walker) was developed. The HDA-NE DNA walker was constructed by modifying hairpin-shaped DNA aligner (HDA) probe and substrate report (SR) probe on the surface of AuNPs. Under normal conditions, HDA and SR remained stable. However, in the presence of miR-373, HDA underwent a conformational transition to an activated structure to continuously cleave the SR probe on the AuNPs with the assistance of Nt.AlwI nicking endonuclease, resulting in sensitive miRNA detection with a detection limit as low as 0.23 pM. Additionally, the proposed HDA-NE DNA walker exhibited high selectivity in distinguishing miRNAs with single base differences and can effectively analyze miR-373 levels in both normal and breast cancer patient serums.

SIGNIFICANCE

The proposed HDA-NE DNA walker system was activated by a conformational change of HDA probe only in the presence of the target miRNA, eliminating the need for a lock probe and without sequence dependence for SR probe. This strategy demonstrated a rapid reaction rate of only 30 min, minimal background noise, and a high signal-to-noise ratio (S/B) compared to capture/lock-based DNA walker. The method is expected to become a powerful tool and play an important role in disease diagnosis and precision therapy.

Biomolecule-regulation of fluorescent probe signaling: Homogeneous rapid portable protease sensing in serum

BACKGROUND

As is well documented, prostate cancer (PCa) being the second most prevalent cancer in men worldwide, emphasizing the importance of early diagnosis for prognosis. However, conventional prostate-specific antigen (PSA) testing lacks sufficient diagnostic efficiency due to its relatively low sensitivity and limited detection range. Mounting evidence suggests that matrix metalloproteinase 9 (MMP-9) expression increases with the aggressive behavior of PCa, highlighting the significance of detecting the serum level of MMP-9 in patients. Developing a non-immune rapid, portable MMP-9 detection strategy and investigating its representativeness of PCa serum markers hold considerable implications.

RESULTS

Herein, our study developed a simple, homogeneous dual fluorescence and smartphone-assisted red-green-blue (RGB) visualization peptide sensor of MMP-9, utilizing cadmium telluride quantum dots (CdTe QDs) and calcein as signal reporters. The essence of our approach revolves around the proteolytic ability of MMP-9, exploiting the selective recognition of molecule-Cu2+ complexes with different molecular weights by CdTe QDs and calcein. Under optimized conditions, the limits of detection (LODs) for MMP-9 were 0.5 pg/mL and 6 pg/mL using fluorescence and RGB values readouts, respectively. Indeed, this strategy exhibited robust specificity and anti-interference ability. MMP-9 was quantified in 42 clinical serum samples via dual-fluorescence analysis, with 12 samples being visually identified with a smartphone. According to receiver operating characteristic curve (ROC) analysis, its sensitivity and specificity were 90 % and 100 %, respectively, with an area under curve (AUC) value of 0.903.

SIGNIFICANCE AND NOVELTY

Of note, the results of the aforementioned analysis were highly consistent with the serum level of PSA, clinical color Doppler flow imaging (CDFI), and histopathological results. Therefore, this simple, rapid, homogeneous fluorescence and visualization strategy can reliably measure MMP-9 levels and exhibit promising potential in point-of-care testing (POCT) applications for PCa patients.

CRISPR-Enhanced Photocurrent Polarity Switching for Dual-lncRNA Detection Combining Deep Learning for Cancer Diagnosis

Abnormal expression in long noncoding RNAs (lncRNAs) is closely associated with cancers. Herein, a novel CRISPR/Cas13a-enhanced photocurrent-polarity-switching photoelectrochemical (PEC) biosensor was engineered for the joint detection of dual lncRNAs, using deep learning (DL) to assist in cancer diagnosis. After target lncRNA-activated CRISPR/Cas13a cleaves to induce DNAzyme bidirectional walkers with the help of cofactor Mg2+, nitrogen-doped carbon-Cu/Cu2O octahedra are introduced into the biosensor, producing a photocurrent in the opposite direction of CdS quantum dots (QDs). The developed PEC biosensor shows high specificity and sensitivity with limits of detection down to 25.5 aM for lncRNA HOTAIR and 53.1 aM for lncRNA MALAT1. More importantly, this platform for the lncRNA joint assay in whole blood can successfully differentiate cancers from healthy people. Furthermore, the DL model is applied to explore the potential pattern hidden in data of the established technology, and the accuracy of DL cancer diagnosis can acquire 93.3%. Consequently, the developed platform offers a new avenue for lncRNA joint detection and early intelligent diagnosis of cancer.

Exosomes based strategies for cardiovascular diseases: Opportunities and challenges

Exosomes, as nanoscale extracellular vesicles (EVs), are secreted by all types of cells to facilitate intercellular communication in living organisms. After being taken up by neighboring or distant cells, exosomes can alter the expression levels of target genes in recipient cells and thereby affect their pathophysiological outcomes depending on payloads encapsulated therein. The functions and mechanisms of exosomes in cardiovascular diseases have attracted much attention in recent years and are thought to have cardioprotective and regenerative potential. This review summarizes the biogenesis and molecular contents of exosomes and details the roles played by exosomes released from various cells in the progression and recovery of cardiovascular disease. The review also discusses the current status of traditional exosomes in cardiovascular tissue engineering and regenerative medicine, pointing out several limitations in their application. It emphasizes that some of the existing emerging industrial or bioengineering technologies are promising to compensate for these shortcomings, and the combined application of exosomes and biomaterials provides an opportunity for mutual enhancement of their performance. The integration of exosome-based cell-free diagnostic and therapeutic options will contribute to the further development of cardiovascular regenerative medicine.

Pushing Forward the DNA Walkers in Connection with Tumor-Derived Extracellular Vesicles

Extracellular vesicles (EVs) are microparticles released from cells in both physiological and pathological conditions and could be used to monitor the progression of various pathological states, including neoplastic diseases. In various EVs, tumor-derived extracellular vesicles (TEVs) are secreted by different tumor cells and are abundant in many molecular components, such as proteins, nucleic acids, lipids, and carbohydrates. TEVs play a crucial role in forming and advancing various cancer processes. Therefore, TEVs are regarded as promising biomarkers for the early detection of cancer in liquid biopsy. However, the currently developed TEV detection methods still face several key scientific problems that need to be solved, such as low sensitivity, poor specificity, and poor accuracy. To overcome these limitations, DNA walkers have emerged as one of the most popular nanodevices that exhibit better signal amplification capability and enable highly sensitive and specific detection of the analytes. Due to their unique properties of high directionality, flexibility, and efficiency, DNA walkers hold great potential for detecting TEVs. This paper provides an introduction to EVs and DNA walker, additionally, it summarizes recent advances in DNA walker-based detection of TEVs (2018-2024). The review highlights the close relationship between TEVs and DNA walkers, aims to offer valuable insights into TEV detection and to inspire the development of reliable, efficient, simple, and innovative methods for detecting TEVs based on DNA walker in the future.

Enhanced Label-Free Photoelectrochemical Strategy for Pollutant Detection: Using Surface Oxygen Vacancies-Enriched BiVO4 Photoanode

Label-free photoelectrochemical sensors have the advantages of high sensitivity and a simple electrode structure. However, its performance is greatly limited due to the photoactive materials' weak photoactivity and poor stability. Herein, a robust homogeneous photoelectrochemical (PEC) aptasensor has been constructed for atrazine (ATZ) based on photoetching (PE) surface oxygen vacancies (Ov)-enriched Bismuth vanadate (BiVO4) (PE-BVO). The surface of the Ov improves the carrier separation ability of BiVO4, thus providing a superior signal substrate for the sensor. A thiol molecular layer self-assembled on PE-BVO acts as a blocker, while 2D graphene acts as a signal-on probe after release from the aptamer-graphene complex. The fabricated sensor has a wide linear detection range of 0.5 pM to 10.0 nM and a low detection limit of 0.34 pM (S/N = 3) for ATZ. In addition, it can efficiently work in a wide pH range (3-13) and high ionic strength (∼6 M Na+), which provides promising opportunities for detecting environmental pollutants under complex conditions.

Exo Ⅲ-assisted amplification signal strategy synergized with Au@Pt NFs/CoSe2 for sensitive detection of enrofloxacin

Overuse of enrofloxacin (ENR) has posed a potential threat to ecosystems and public health, so it is critical to sensitive and accurate determination of ENR residues. In this work, a novel ultra-sensitive and specific electrochemical aptasensor was fabricated based on the cobalt diselenide loaded gold and platinum nanoflowers (Au@Pt NFs/ CoSe2) and Exonuclease III (Exo III)-assisted cycle amplification strategy for the detection of ENR. Au@Pt NFs/ CoSe2 nanosheets as the substrate material, with large surface area, accelerate electron transfer and attach more DNA probes on the electrode substrate, have effectively enhanced the electrochemical performance of the electrode. With the existence of Enrofloxacin (ENR), the aptamer recognizes and binds to ENR, thus the signal probe cDNA was released and immobilized onto the electrode surface to hybridized with methylene blue (MB) labelled DNA (MB-DNA), thereby triggering the Exo III-assisted cycle for further signal amplification. As expected, the prepared aptasensor demonstrated excellent sensitivity and selectivity, with a wide linear range from 5.0 × 10-6 ng/mL to 1.0 × 10-2 ng/mL for ENR, a low detection limit of 1.59 × 10-6 ng/mL. Consequently, this strategy provided a promising avenue for ultrasensitive and accurate detection of ENR in milk samples.

Development of a Multiplexed Electrochemical Aptasensor for the Detection of Cyanotoxins

In this study, we report a multiplexed platform for the simultaneous determination of five marine toxins. The proposed biosensor is based on a disposable electrical printed (DEP) microarray composed of eight individually addressable carbon electrodes. The electrodeposition of gold nanoparticles on the carbon surface offers high conductivity and enlarges the electroactive area. The immobilization of thiolated aptamers on the AuNP-decorated carbon electrodes provides a stable, well-orientated and organized binary self-assembled monolayer for sensitive and accurate detection. A simple electrochemical multiplexed aptasensor based on AuNPs was designed to synchronously detect multiple cyanotoxins, namely, microcystin-LR (MC-LR), Cylindrospermopsin (CYL), anatoxin-α, saxitoxin and okadaic acid (OA). The choice of the five toxins was based on their widespread presence and toxicity to aquatic ecosystems and humans. Taking advantage of the conformational change of the aptamers upon target binding, cyanotoxin detection was achieved by monitoring the resulting electron transfer increase by square-wave voltammetry. Under the optimal conditions, the linear range of the proposed aptasensor was estimated to be from 0.018 nM to 200 nM for all the toxins, except for MC-LR where detection was possible within the range of 0.073 to 150 nM. Excellent sensitivity was achieved with the limits of detection of 0.0033, 0.0045, 0.0034, 0.0053 and 0.0048 nM for MC-LR, CYL, anatoxin-α, saxitoxin and OA, respectively. Selectivity studies were performed to show the absence of cross-reactivity between the five analytes. Finally, the application of the multiplexed aptasensor to tap water samples revealed very good agreement with the calibration curves obtained in buffer. This simple and accurate multiplexed platform could open the window for the simultaneous detection of multiple pollutants in different matrices.

Single-Atom Iron Doped Carbon Dots with Highly Efficient Electrochemiluminescence for Ultrasensitive Detection of MicroRNAs

Herein, single-atom iron doped carbon dots (SA Fe-CDs) were successfully prepared as novel electrochemiluminescence (ECL) emitters with high ECL efficiency, and a biosensor was constructed to ultrasensitively detect microRNA-222 (miRNA-222). Importantly, compared with the conventional without single-atom doped CDs with low ECL efficiency, SA Fe-CDs exhibited strong ECL efficiency, in which single-atom iron as an advanced coreactant accelerator could significantly enhance the generation of reactive oxygen species (ROS) from the coreactant S2O82- for improving the ECL efficiency. Moreover, a neoteric amplification strategy combining the improved strand displacement amplification with Nt.BbvCI enzyme-induced target amplification (ISDA-EITA) could produce 4 output DNAs in every cycle, which greatly improved the amplification efficiency. Thus, a useful ECL biosensor was built with a detection limit of 16.60 aM in the range of 100 aM to 1 nM for detecting traces of miRNA-222. In addition, miRNA-222 in cancer cell lysate (MHCC-97L) was successfully detected by using the ECL biosensor. Therefore, this strategy provides highly efficient single-atom doped ECL emitters for the construction of sensitive ECL biosensing platforms in the biological field and clinical diagnosis.

An acid-responsive DNA hydrogel-mediated cascaded enzymatic nucleic acid amplification system for the sensitive imaging of alkaline phosphatase in living cells

Alkaline phosphatase (ALP) is a class of hydrolase that catalyzes the dephosphorylation of phosphorylated species in biological tissues, playing an important role in many physiological and pathological processes. Sensitive imaging of ALP activity in living cells is contributory to the research on these processes. Herein, we propose an acid-responsive DNA hydrogel to deliver a cascaded enzymatic nucleic acid amplification system into cells for the sensitive imaging of intracellular ALP activity. The DNA hydrogel is formed by two kinds of Y-shaped DNA monomers and acid-responsive cytosine-rich linkers. The amplification system contained Bst DNA polymerase (Bst DP), Nt.BbvCI endonuclease, a Recognition Probe (RP, containing a DNAzyme sequence, a Nt.BbvCI recognition sequence, and a phosphate group at the 3'-end), and a Signal Probe (SP, containing a cleavage site for DNAzyme, Cy3 and BHQ2 at the two ends). The amplification system was trapped into the DNA hydrogel and taken up by cells, and the cytosine-rich linkers folded into a quadruplex i-motif in the acidic lysosomes, leading to the collapse of the hydrogel and releasing the amplification system. The phosphate groups on RPs were recognized and removed by the target ALP, triggering a polymerization-nicking cycle to produce large numbers of DNAzyme sequences, which then cleaved multiple SPs, restoring Cy3 fluorescence to indicate the ALP activity. This strategy achieved sensitive imaging of ALP in living HeLa, MCF-7, and NCM460 cells, and realized the sensitive detection of ALP in vitro with a detection limit of 2.0 × 10-5 U mL-1, providing a potential tool for the research of ALP-related physiological and pathological processes.

Efficient DNA walker guided by ordered cruciform-shaped DNA track for ultrasensitive and rapid electrochemical detection of lead ion

The rational design of DNA tracks is an effective pathway to guide the autonomous movement and high-efficiency recognition in DNA walkers, showing outstanding advantages for the cascade signal amplification of electrochemical biosensors. However, the uncontrolled distance between two adjacent tracks on the electrode could increase the risk of derailment and interruption of the reaction. Hence, a novel four-way balanced cruciform-shaped DNA track (C-DNT) was designed as a structured pathway to improve the effectiveness and stability of the reaction in DNA walkers. In this work, two kinds of cruciform-shaped DNA were interconnected as a robust structure that could avoid the invalid movement of the designed DNA walker on the electrode. When hairpin H2 was introduced onto the electrode, the strand displacement reaction (SDR) effectively triggered movements of the DNA walker along the cruciform-shaped track while leaving ferrocene (Fc) on the electrode, leading to a significant enhancement of the electrochemical signal. This design enabled the walker to move in an excellent organized and controllable manner, thus enhancing the reaction speed and walking efficiency. Compared to other walkers moving on random tracks, the reaction time of the C-DNT-based DNA walker could be reduced to 20 min. Lead ion (Pb2+) was used as a model target to evaluate the analytical performance of this biosensor, which exhibited a low detection limit of 0.033 pM along with a wide detection ranging from 0.1 pM to 500 nM. This strategy presented a novel concept for designing a high-performance DNA walker-based sensing platform for the detection of contaminants.

Visually evaluating drug efficacy in living cells using COF-based fluorescent nanoprobe via CHA amplified detection of miRNA and simultaneous apoptosis imaging

BACKGROUNDS

Cancer is a highly fatal disease which is close relative of miRNA aberrant expression and apoptosis disorders. Elucidation of the therapeutic efficacy through investigating the changes in miRNA and apoptosis holds immense importance in advancing the development of miRNA-based precision therapy. However, it remains a challenge as how to visually evaluate the efficacy during protocol optimization of miRNA-based anticancer drugs at the cellular level. Therefore, exploring effective and noninvasive methods for real-time monitoring of therapeutic efficacy in living cells is of great significance.

RESULTS

Herein, we reported a novel fluorescent nanoprobe COF-H1/H2-Peptide for visually evaluating drug efficacy in living cells through amplified imaging of low-abundant miRNA-221 with catalytic hairpin assembly (CHA) circle amplification, as well as simultaneous caspase-3 imaging. With strong stability and good biocompatibility, this newly fabricated amplified nanoprobe showed high sensitivity and specificity for the detection of miRNA-221 and caspase-3, and the limit of detection (LOD) of miRNA-221 was as low as 2.79 pM. The fluorescent imaging results showed that this amplified nanoprobe could not only detect caspase-3 in living cells, but also effectively detect low levels of miRNA-221 with increasing anticancer drug concentration and treatment time. The smart nanoprobe had effective performance for optimizing miRNA-based drug treatment schedules by dual-color fluorescence imaging.

SIGNIFICANCE

This nanoprobe combined CHA amplified detection of intracellular miRNA-221 and synchronous apoptosis imaging, with excellent sensitivity for the detection of cellular low-level miRNA, enabling the realization of real-time assessment of the efficacy of miRNA-based therapy in living cells. This work presents a promising approach for revealing the regulatory mechanisms between miRNAs and apoptosis in cancer occurrence, development, and treatment.

Multiple signal amplification strategy induced by biomarkers of lung cancer: A self-powered biosensing platform adapted for smartphones

Lung cancer is a major malignant cancer with low survival rates, and early diagnosis is crucial for effective treatment. Herein, a biosensing platform that is self-powered derived from a capacitor-coupled EBFC has been developed for ultra-sensitive real-time identification of microRNA-21 (miRNA-21) with the assistance of a mobile phone. The flexible substrate of the platform is prepared on a carbon paper modified with graphdiyne and gold nanoparticles. The biosensor employs DNAzyme-mediated dual strand displacement amplification, which enhances the signal output intensity of the EBFC and improves selectivity. The coupling of the capacitor with the EBFC significantly amplifies the sensing signal, causing a 10.6-fold surge in current respond and further improving the sensitivity of the sensing platform. The established detection approach demonstrates a linear relationship varied from 0.0001 to 10,000 pM, with a sensitivity down to 32.3 aM as the minimum detectable limit, which has been effectively utilized for detecting miRNA-21 in practical samples. This sensing system provides strong support for the construction of portable detection devices, and the strategy of the platform construction provides an effective method for ultra-sensitive and accurate detection of miRNA, holding great potential in clinical diagnosis, prognosis evaluation, and drug screening for cancer.

Electrochemical detection of glutathione based on accelerated CRISPR/Cas12a trans-cleavage with MnO2 nanosheets

The CRISPR/Cas12a system is accelerated by glutathione-mediated reduction of MnO2 nanosheets. By monitoring the trans-cleavage of the DNA probe, an electrochemical method for glutathione assay is fabricated, with the detection limit of 3.5 pM. It provides a promising tool for plasma analysis with satisfactory performance, indicating the broad application prospects of this glutathione assay.

A novel nanoprobe for visually investigating the controversial role of miRNA-34a as an oncogene or tumor suppressor in cancer cells

MiRNA-targeted therapy has become a hot topic in current cancer research. The key to this treatment strategy is to clarify the specific role of miRNA in cancer. However, the roles of some miRNAs acting as oncogenic or tumor suppressors are still controversial, which are influenced by different tumor types, even in the same cancer type. Hence, we designed a novel fluorescent nanoprobe based on polydopamine nanoparticles (PDA NPs) for simultaneously detecting caspase-3 and miRNA-34a within living cells. The specific role of miRNA-34a in different cancer cells could be further identified by studying the expression alterations of caspase-3 and miRNA-34a. Confocal imaging indicated that miRNA-34a indeed acted as a tumor suppressor in anticancer drug-treated MCF-7 and HeLa cells, where the effect of miRNA-34a remains controversial. The designed nanoprobe can offer a promising approach to ascertain the oncogenic or tumor-suppressing role of miRNA in different cancer cells with a simple visualization method, which has valuable implications for exploring the practicability of precision therapy focused on miRNA and evaluating the efficacy of new miRNA-targeted anticancer medications.