Dual-mode of electrochemical-colorimetric imprinted sensing strategy based on self-sacrifice beacon for diversified determination of cardiac troponin I in serum

Electroactive Nanomaterials for the Prevention and Treatment of Heart Failure: From Materials and Mechanisms to Applications

Heart failure (HF) represents a cardiovascular disease that significantly threatens global well-being and quality of life. Electroactive nanomaterials, characterized by their distinctive physical and chemical properties, emerge as promising candidates for HF prevention and management. This review comprehensively examines electroactive nanomaterials and their applications in HF intervention. It presents the definition, classification, and intrinsic characteristics of conductive, piezoelectric, and triboelectric nanomaterials, emphasizing their mechanical robustness, electrical conductivity, and piezoelectric coefficients. The review elucidates their applications and mechanisms: 1) early detection and diagnosis, employing nanomaterial-based sensors for real-time cardiac health monitoring; 2) cardiac tissue repair and regeneration, providing mechanical, chemical, and electrical stimuli for tissue restoration; 3) localized administration of bioactive biomolecules, genes, or pharmacotherapeutic agents, using nanomaterials as advanced drug delivery systems; and 4) electrical stimulation therapies, leveraging their properties for innovative pacemaker and neurostimulation technologies. Challenges in clinical translation, such as biocompatibility, stability, and scalability, are discussed, along with future prospects and potential innovations, including multifunctional and stimuli-responsive nanomaterials for precise HF therapies. This review encapsulates current research and future directions concerning the use of electroactive nanomaterials in HF prevention and management, highlighting their potential to innovating in cardiovascular medicine.

Molecularly imprinted polymer sensors for biomarker detection in cardiovascular diseases

Cardiovascular diseases (CVDs) are recognized as a significant threat to global health. The rapid, sensitive, and precise measurement of relevant biomarkers is essential for the timely diagnosis of CVDs. Molecularly imprinted polymers (MIPs), which act as artificial receptor recognition materials, have been extensively utilized in the detection of CVD biomarkers. Their widespread application is due to their cost-effectiveness, physical and chemical stability, straightforward preparation processes, and excellent compatibility with various sensor types. This review introduces the principles of MIP sensors in combination with electrochemical, optical, thermal transfer, and acoustic detection techniques for detecting CVD-related biomarkers. It then discusses methods developed over the past decade for detecting biomarkers of three major CVDs-coronary artery disease (CAD), acute myocardial infarction (AMI), and heart failure (HF)-using MIP sensors. Finally, the review summarizes the potential of MIP sensors in CVD biomarker detection and provides an outlook on future research directions.

Simple strategy for dual-responsive ratio electrochemical-colorimetric detection of nitrite in food and environment

A dual-responsive ratio electrochemical-colorimetric method for nitrite (NO2-) is established based on the combination of nanoenzyme (Mn3O4) catalysis with diazotization reactions. The Mn3O4 can oxidize colorless 3,3',5,5'-tetramethylbenzidine (TMB) into blue TMBox. The NO2- induces the diazotization reaction of TMBox, leading to a decrease of  the signal at 652 nm and the generation of a new signal from diazotized TMBox at 445 nm. Furthermore, the presence of NO2- reduces the electrochemical oxidation signal of TMB and simultaneously provides its electrochemical signal. Compared with traditional single-mode detection, dual-mode detection offers higher sensitivity, lower detection limits, and better interference resistance. The inherent advantages of this method make it feasible to detect NO2- in real samples, offering broad prospects for applications in food safety and environmental monitoring.

Fast Isolation and Sensitive Multicolor Visual Detection of Small Extracellular Vesicles by Multifunctional Polydopamine Nanospheres

Small extracellular vesicles (sEVs) assume pivotal roles as vital messengers in intercellular communication, boasting a plethora of biological functions and promising clinical applications. However, efficient isolation and sensitive detection of sEVs continue to present formidable challenges. In this study, we report a novel method for fast isolation and highly sensitive multicolor visual detection of sEVs using aptamer-functionalized polydopamine nanospheres (SIMPLE). In the SIMPLE strategy, aptamer-functionalized polydopamine nanospheres (Apt-PDANS) with 170 nm diameters were synthesized and exhibited a remarkable ability to selectively bind to specific proteins on the surface of sEVs. The binding between sEVs and Apt-PDANS engenders an increase in the overall size of the sEVs, allowing fast isolation of sEVs by filtration (a filter membrane with a pore size of 200 nm). The fast isolation strategy not only circumvents the interference posed by unbound proteins and excessive probes as well as the intricacies associated with conventional ultracentrifugation methods but also expedites the separation of sEVs. Concurrently, the incorporation of Fe3+-doped PDANS permits the multicolor visual detection of sEVs, enabling quantitative analysis by the discernment of visual cues. The proposed strategy achieves a detection limit of 3.2 × 104 sEV mL-1 within 1 h, devoid of any reliance on instrumental apparatus. Furthermore, we showcase the potential application of this methodology in epithelial-mesenchymal transition monitoring and cancer diagnosis, while also envisioning its widespread adoption as a straightforward, rapid, sensitive, and versatile platform for disease monitoring and functional exploration.

An Electrochemical Biosensor for the Detection of Pulmonary Embolism and Myocardial Infarction

Due to the clinical similarities between pulmonary embolism (PE) and myocardial infarction (MI), physicians often encounter challenges in promptly distinguishing between them, potentially missing the critical window for the correct emergency response. This paper presents a biosensor, termed the PEMI biosensor, which is designed for the identification and quantitative detection of pulmonary embolism or myocardial infarction. The surface of the working electrode of the PEMI biosensor was modified with graphene oxide and silk fibroin to immobilize the mixture of antibodies. Linear sweep voltammetry was employed to measure the current-to-potential mapping of analytes, with the calculated curvature serving as a judgment index. Experimental results showed that the curvature exhibited a linear correlation with the concentration of antigen FVIII, and a linear inverse correlation with the concentration of antigen cTnI. Given that FVIII and cTnI coexist in humans, the upper and lower limits were determined from the curvatures of a set of normal concentrations of FVIII and cTnI. An analyte with a curvature exceeding the upper limit can be identified as pulmonary embolism, while a curvature falling below the lower limit indicates myocardial infarction. Additionally, the further the curvature deviates from the upper or lower limits, the more severe the condition. The PEMI biosensor can serve as an effective detection platform for physicians.

Development of a simple polymer-based sensor for detection of the Pirimicarb pesticide

In this study, a sensitive and selective fluorescent chemosensor was developed for the determination of pirimicarb pesticide by adopting the surface molecular imprinting approach. The magnetic molecularly imprinted polymer (MIP) nanocomposite was prepared using pirimicarb as the template molecule, CuFe2O4 nanoparticles, and graphene quantum dots as a fluorophore (MIP-CuFe2O4/GQDs). It was then characterized using X-ray diffraction (XRD) technique, Fourier transforms infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), and transmission electron microscopy (TEM). The response surface methodology (RSM) was also employed to optimize and estimate the effective parameters of pirimicarb adsorption by this polymer. According to the experimental results, the average particle size and imprinting factor (IF) of this polymer are 53.61 nm and 2.48, respectively. Moreover, this polymer has an excellent ability to adsorb pirimicarb with a removal percentage of 99.92 at pH = 7.54, initial pirimicarb concentration = 10.17 mg/L, polymer dosage = 840 mg/L, and contact time = 6.15 min. The detection of pirimicarb was performed by fluorescence spectroscopy at a concentration range of 0-50 mg/L, and a sensitivity of 15.808 a.u/mg and a limit of detection of 1.79 mg/L were obtained. Real samples with RSD less than 2 were measured using this chemosensor. Besides, the proposed chemosensor demonstrated remarkable selectivity by checking some other insecticides with similar and different molecular structures to pirimicarb, such as diazinon, deltamethrin, and chlorpyrifos.

Electrochemical biosensor for highly sensitive detection of cTnI based on a dual signal amplification strategy of ARGET ATRP and ROP

Cardiac troponin I (cTnI), a gold biomarker for the diagnosis of acute myocardial infarction (AMI), plays a vital role in the early diagnosis, treatment and prognosis analysis of AMI. In this paper, an electrochemical biosensor for the highly sensitive determination of cTnI was fabricated based on the dual signal amplification strategy of electron transfer atom transfer radical polymerization (ARGET ATRP) and ring-opening polymerization (ROP) for the first time. Briefly, the thiolate cTnI-aptamer 1, which was bonded to the electrode via Au-S bonds, specifically captured cTnI to the electrode surface. Then, cTnI-aptamer 2 (Apt2) was successfully introduced to the electrode surface to form Apt-cTnI-Apt sandwich structure. Subsequently, the initiator BIBB was connected to Apt2 through bromination reaction, and then the resulting ATRP polymer was employed as a macromolecular initiator for the succeeding reaction. Next, the monomers, α-amino acid-N-carboxylic acid anhydride ferrocene derivatives (NCA-Fc), used for the ROP reaction produced numerous electroactive polymers on the electrode surface. The dual action of ARGET ATRP and ROP significantly improved sensitivity of cTnI biosensor assay, the prepared biosensor displayed a wide linear detection range from 100 fg mL-1 to 100 ng mL-1, with a detection limit of 32.24 fg mL-1. The method exhibited favorable selectivity, simple operation and excellent stability. Furthermore, the biosensor still rendered satisfactory analytical performance in the detection of clinical serum samples, indicating the application potential in clinical diagnosis.

Dual-mode sensing chip for photoelectrochemical and electrochromic visual determination of deoxynivalenol mycotoxin

The successful development of a dual-mode sensing chip for deoxynivalenol (DON) detection using photoelectrochemical (PEC) and electrochromic visualization techniques is reported. By laser etching technology, different functional areas, including the photoanode, the cathode, and the electrochromic area, are fabricated on indium tin oxide (ITO) glass. Then, these three areas are further respectively modified with PEC active materials, platinum nanoparticles, and Prussian blue. Under light illumination, photocurrents generate between the photoanode and the cathode due to the separation of photo-induced electrons and holes in the TiO2/3DNGH material. Meanwhile, the photo-induced electrons are transferred to Prussian blue on the visualization area, which will be reduced to colorless Prussian white. The binding of DON molecules and aptamers can promote electron transfer and reduce the recombination of electrons and holes, allowing for simultaneous quantitative detection of DON using either the photocurrent or color change. The sensor chip has a broad detection range of DON concentrations of 1 fg⋅mL-1 to 100 pg⋅mL-1 in the PEC mode with the limit of detection of 0.37 fg⋅mL-1, and 1 to 250 ng⋅mL-1 in the visualization mode with the limit of detection of 0.51 ng⋅mL-1. This portable dual-mode sensor chip can be used in both laboratory and field settings without the need for specialized instruments, making it a powerful tool for ensuring food safety. At the same time, the analysis of the standard addition method of the actual sample by using the sensor chip shows that, in the PEC mode, the recoveries of the dual-mode aptasensor chip were 91.3 to 99.0% with RSD values of 1.73~2.55%, and in visualization mode, the recoveries of the dual-mode aptasensor chip were 99.2 to 102.0% with RSD values of 1.00~6.21%, which indicate good accuracy and reproducibility.

In situ green synthesis of the nanocomposites of MnO2/graphene as an oxidase mimic for sensitive colorimetric and electrochemical dual-mode biosensing

Herein we report the colorimetry and an electrochemical for the determination of dopamine (DA) by using MnO2 nanoparticles and graphene nanosheets composite (MnO2@G) that display oxidase mimicking property. MnO2@G could directly oxidize colorless 3,3',5,5'-tetramethylbenzidine (TMB) into a blue product (oxTMB) without extra oxidants such as H2O2. Nevertheless, the presence of DA will inhibit the TMB oxidation due to the presence of the competitive reaction of MnO2@G and DA, giving a product color change from blue to colorless. A colorimetric assay for detect the concentration of DA was worked out according to this finding. Response is linear in the 0.1 to 15 μM DA concentration range, and the detection limit is 0.14 μM. Wider detection range is achieved in an electrochemical method which is due to the pronounced electrocatalytic activity of MnO2@G. The MnO2@G was modified on the surface of the glassy carbon electrode in order to fabricate one type electrochemical sensor. The sensor achieves a wide detection two linear ranges from 0.4 to 70 μM, with the detection limit of 1.16 μM. The detection of DA in real serum sample proved that the nanozyme based on MnO2@G could be developed into a colorimetry and electrochemical dual-readout sensing platform.

Photo-enhanced electrochemical and colorimetric dual-modal aptasensing for aflatoxin B1 detection based on graphene-gold Schottky contact

A photo-enhanced electrochemical (PEEC) and colorimetric (CM) dual-modal aptasensor was developed with rGO-AuNP Schottky contact for AFB1 monitoring. The PEEC mode allowed the ultrasensitive quantitation based on the photo-enhanced electroactivity mechanism, while the CM mode offered a rapid threshold-level qualitative assay with a portable colorimeter.

Molecular Complementarity of Proteomimetic Materials for Target-Specific Recognition and Recognition-Mediated Complex Functions

As biomolecules essential for sustaining life, proteins are generated from long chains of 20 different α-amino acids that are folded into unique 3D structures. In particular, many proteins have molecular recognition functions owing to their binding pockets, which have complementary shapes, charges, and polarities for specific targets, making these biopolymers unique and highly valuable for biomedical and biocatalytic applications. Based on the understanding of protein structures and microenvironments, molecular complementarity can be exhibited by synthesizable and modifiable materials. This has prompted researchers to explore the proteomimetic potentials of a diverse range of materials, including biologically available peptides and oligonucleotides, synthetic supramolecules, inorganic molecules, and related coordination networks. To fully resemble a protein, proteomimetic materials perform the molecular recognition to mediate complex molecular functions, such as allosteric regulation, signal transduction, enzymatic reactions, and stimuli-responsive motions; this can also expand the landscape of their potential bio-applications. This review focuses on the recognitive aspects of proteomimetic designs derived for individual materials and their conformations. Recent progress provides insights to help guide the development of advanced protein mimicry with material heterogeneity, design modularity, and tailored functionality. The perspectives and challenges of current proteomimetic designs and tools are also discussed in relation to future applications.

Dual signal amplified electrochemical aptasensor based on PEI-functionalized GO and ROP for highly sensitive detection of cTnI

Cardiac troponin I (cTnI) is considered as the gold standard for the diagnosis of acute myocardial infarction (AMI) because of its excellent specificity and sensitivity. Herein, a novel aptasensor based on the dual signal amplification strategy of Polyethyleneimine functionalized Graphene oxide (GO) and ring-opening polymerization (ROP) for the first time was successfully constructed to achieve high sensitivity detection of cTnI. Briefly, cTnI-aptamer 1 (Apt1) was immobilized on the surface of gold electrode by self-assembly of Au-S bonds to specifically capture cTnI. After specific recognition of cTnI, Apt2 coated PEI-functionalized GO composites acted as macroinitiators for the subsequent ROP reaction. Next, α-amino acid-N-carboxylic acid anhydride ferrocene derivatives (NCA-Fc), the monomer for ROP reaction, was added to the electrode surface. The combined application of PEI-functionalized GO and NCA-Fc better achieves the high sensitivity and signal amplification of the aptasensor. Under optimal conditions, the aptasensor exhibited a wide linear range of 10 fg mL^-1 to 10 ng mL^-1 and the limit of detection was 3.78 fg mL^-1. Moreover, this method displayed the advantages of good selectivity, simple operation and excellent stability. Meanwhile, the aptasensor had good accuracy and applicability even in real serum samples analysis, demonstrating its considerable application potential in biomedical assays.

Self-corrected dual-optical immunosensors using carbon dots@SiO2@MnO2 improving diethyl phthalate detection accuracy

The traditional immunoassay is widely used for pollutant detection and bioanalysis, but there are still some challenges in ensuring its sensitivity and reliable accuracy. Dual-optical measurement can prove mutual evidence to effectively improve the accuracy of the method by self-correction, which will overcome this problem. In this study, we developed a "visualization and sensing" dual-modal immunoassay based on blue carbon dots@SiO₂@MnO₂ (B-CDs@SiO₂@MnO₂) as "color and fluorescence" immunosensors. Here, MnO₂ nanosheets have the activity of simulating oxidase. 3,3', 5,5'-Tetramethylbenzidine (TMB) can be oxidized to TMB²⁺ under acidic conditions and the color of the solution from colorless to yellow. On the other hand, the MnO₂ nanosheets can quench the fluorescence of B-CDs@SiO₂. After adding ascorbic acid (AA), MnO₂ nanosheets were reduced to Mn²⁺, thereby the fluorescence of B-CDs@SiO₂ was restored. Under the optimum conditions, as the concentration of target substance (diethyl phthalate) increased from 0.05 to 100 ng/mL, the method showed a good linear relationship. The fluorescence measurement signal and the color change signal of the solution visualization support each other and give the information of the corresponding material content. The results of the dual-optical immunoassay maintain good consistency, which proves the accuracy of the developed dual-optical immunoassay for detection of diethyl phthalate is reliable. Additionally, it is demonstrated that the dual-modal method exhibits high accuracy and stability in the assays, pointing to a broad range of application prospects in pollutant analysis.

Gold nanocluster-confined covalent organic frameworks as bifunctional probes for electrochemiluminescence and colorimetric dual-response sensing of Pb2

The development of bifunctional signal probes based on a single component is highly desirable for sensitive and simple dual-mode detection of Pb²⁺. Here, novel gold nanocluster-confined covalent organic frameworks (AuNCs@COFs) were fabricated as a bisignal generator to enable electrochemiluminescence (ECL) and colorimetric dual-response sensing. AuNCs with both intrinsic ECL and peroxidase-like activity were confined into the ultrasmall pores of the COFs via an in situ growth method. On the one hand, the space-confinement effect of the COFs closed the ligand motion-induced nonradiative transition channels of the AuNCs. As a result, the AuNCs@COFs exhibited a 3.3-fold enhancement in anodic ECL efficiency compared to the solid-state aggregated AuNCs using triethylamine as the coreactant. On the other hand, due to the outstanding spatial dispersibility of the AuNCs in the structurally ordered COFs, a high density of active catalytic sites and accelerated electron transfer were obtained, leading to the promotion of the enzyme-like catalytic capacity of the composite. To validate its practical applicability, a Pb²⁺-triggered dual-response sensing system was proposed based on the aptamer-regulated ECL and peroxidase-like activity of the AuNCs@COFs. Sensitive determinations down to 7.9 pM for the ECL mode and 0.56 nM for the colorimetric mode were obtained. This work provides an approach for designing single element-based bifunctional signal probes for dual-mode detection of Pb²⁺.

State-of-the-art molecular imprinted colorimetric sensors and their on-site inspecting applications

Molecular imprinted colorimetric sensors can realize visual semi-quantitative analysis without the use of any equipment. With the advantages of low cost, fast response, ease of handling, and excellent recognition ability, the molecular imprinted colorimetric sensor shows great application potential in the field of sample rapid assay. Molecular imprinted colorimetric sensors can be prepared in various forms to meet the needs of different sample determination, such as film, hydrogel, strip, and adsorption coating. In this review, the preparation methods for various types of molecularly imprinted colorimetric sensors are systematically introduced. Their applications in the field of on-site biological sample detection, drug detection, disease treatment, chiral substance detection and separation, environmental analysis, and food safety detection are introduced. The limitations encountered in the practical application are presented, and the future development directions prospect.

Epitope imprinted polymeric materials: application in electrochemical detection of disease biomarkers

Epitope imprinting is a promising method for creating specialized recognition sites that resemble natural biorecognition elements. Epitope-imprinted materials have gained a lot of attention recently in a variety of fields, including bioanalysis, drug delivery, and clinical therapy. The vast applications of epitope imprinted polymers are due to the flexibility in choosing monomers, the simplicity in obtaining templates, specificity toward targets, and resistance to harsh environments along with being cost effective in nature. The "epitope imprinting technique," which uses only a tiny subunit of the target as the template during imprinting, offers a way around various drawbacks inherent to biomacromolecule systems i.e., traditional molecular imprinting techniques with regards to the large size of proteins, such as the size, complexity, accessibility, and conformational flexibility of the template. Electrochemical based sensors are proven to be promising tool for the quick, real-time monitoring of biomarkers. This review unravels epitope imprinting techniques, approaches, and strategies and highlights the applicability of these techniques for the electrochemical quantification of biomarkers for timely disease monitoring. In addition, some challenges are discussed along with future prospective developments.

Salmonella typhimurium strip based on the photothermal effect and catalytic color overlap of PB@Au nanocomposite

This work reports a sensitive and accurate multimode detection method to detect Salmonella typhimurium using inherent color, photothermal and catalytic properties of Prussian blue@gold nanoparticles (PB@Au). The inherent color of PB@Au can realize direct visual detection while the temperature increase (ΔT) of it can realize sensitive and quantitative photothermal detection. Moreover, catalytic coloration detection is applied to further amplify detection signal. The risk limit, prevention and control of Salmonella typhimurium can be more intuitively displayed through catalytic color overlap degree between PB@Au and catalytic product. The sensitivity of method is improved through photothermal and catalytic coloration detection (10¹ CFU·mL^-1) compared with direct visual detection (10² CFU·mL^-1). The multimode detection improves the accuracy of method, and exhibits good repeatability, acceptable selectivity and stability. This method is also successfully applied in real samples, displaying its good practical applicability.

High-sensitive and disposable myocardial infarction biomarker immunosensor with optofluidic microtubule lasing

The early diagnosis of myocardial infarction can significantly improve the survival rate in emergency treatment, which is mainly implemented by the immunoassay for myocardial infarction biomarkers such as cardiac troponins in blood. In this work, a disposable optofluidic microtubule whispering gallery mode (WGM) immunosensor for label-free cardiac troponin I-C (cTnI-C) complex detection has been proposed and demonstrated with active interrogation enhancement. The disposable microtubule is simply fabricated by a silica capillary with pressurized tapering technology for thin-wall, and the cTnI antibodies are immobilized on the inner wall surface of the microtubule through the self-adherent polydopamine substrate. By configuring the two coupling microfibers, the double-fiber-coupled microtubule cavity can serve as a tunable filter for the mutual-coupled polarimetric fiber ring laser (FRL), whose output laser wavelength is determined by the cTnI-C concentration in the optofluidic microtubule with inherent microfluidic channel. Due to the cyclic-cumulative gain of the FRL, the characteristic resonant peak of optical sensing signal is enhanced in the spectral width compression and the optical signal-to-noise ratio improvement, and therefore the optical immunosensor for cTnI-C can be achieved by tracking the output laser wavelength of the FRL conveniently. The dynamic binding and unbinding process of cTnI-C antigen-antibody is illustrated by monitoring the lasing peak wavelength continuously. Our all-fiber immunosensor demonstrated here has the advantages of fast label-free detection, real-time monitor, high sensitivity and disposable sensing element, which can be an innovative detecting tool in early diagnosis of myocardial infarction.

Application progress of magnetic molecularly imprinted polymers chemical sensors in the detection of biomarkers

Specific recognition and highly sensitive detection of biomarkers play an essential role in identification, early diagnosis and prevention of many diseases. Magnetic molecularly imprinted polymers (MMIPs) have been widely used to capture biomimetic receptors for targets in various complex matrices due to their superior recognition ability, structural stability, and rapid separation characteristics, which overcome the existing deficiencies of traditional recognition elements such as antibodies, aptamers. The integration of MMIPs as recognition elements with chemical sensors opens new opportunities for the development of advanced analytical devices with improved selectivity and sensitivity, shorter analysis time, and lower cost. Recently, MMIPs-chemical sensors (MMIPs-CS) have made significant progress in detection, but many challenges and development spaces remain. Therefore, this review focuses on the research progress of the sensor based on biomarker detection and introduces the surface modification of the magnetic support material used to prepare high selective MMIPs, as well as the selective extraction of target biomarkers by MMIPs from the complex biological sample matrix. Based on the understanding of optical sensors and electrochemical sensors, the applications of MMIPs-optical sensors (MMIPs-OS) and MMIPs-electrochemical sensors (MMIPs-ECS) for biomarker detection were reviewed and discussed in detail. Moreover, it provides an overview of the challenges in this research area and the potential strategies for the rational design of high-performance MMIPs-CS, accelerating the development of multifunctional MMIPs-CS.

Dual-Mode Sensing Platform for Electrochemiluminescence and Colorimetry Detection Based on a Closed Bipolar Electrode

Development of sensors uniting different sensing principles is in line with the concept of reliable, comprehensive, and diversified equipment construction. However, the current exploration in this field is obstructed by compromise of reaction conditions and inevitable mutual interference arising from different sensing modes. This work reported a closed bipolar electrode (c-BPE) strategy for dual-modality detection or dual-target detection. To this end, a c-BPE sensing platform installed in physically separated anode and cathode compartments was well designed and carefully optimized. If luminol was present in the anode section and Prussian blue (PB) was at the cathode part, single stimulation could realize electrochemiluminescence (ECL) from luminol at the anode and conversion of PB to Prussian white (PW) at the cathode. The latter reaction helped elevate the ECL signal and also prepared for colorimetric detection as color change from PW to PB under the trigger of oxidant (like H₂O₂) was used to track the content of the oxidant. Thus, dual signals were obtained for dual-modality detection of single target or the detection of different targets was realized at different poles. Detection of glucose was carried out to validate the application for dual-modality detection, while VLDL/AChE and NADH/H₂O₂ assays illustrated the potential of dual-target detection. The proposed platform possesses outstanding sensing performance including selectivity, repeatability, long-term stability, accuracy, and so forth. This work implements a breakthrough in designing dual-mode sensors and is expected to present a rational basis for development of a diversified sensing platform.

Electrochemical strategies for the detection of cTnI

Acute myocardial infarction (AMI) is the main cause of death from cardiovascular diseases. Thus, early diagnosis of AMI is essential for the treatment of irreversible damage from myocardial infarction. Traditional electrocardiograms (ECG) cannot meet the specific detection of AMI. Cardiac troponin I (cTnI) is the main biomarker for the diagnosis of myocardial infarction, and the detection of cTnI content has become particularly important. In this review, we introduced and compared the advantages and disadvantages of various cTnI detection methods. We focused on the analysis and comparison of the main indicators and limitations of various cTnI biosensors, including the detection range, detection limit, specificity, repeatability, and stability. In particular, we pay more attention to the application and development of electrochemical biosensors in the diagnosis of cardiovascular diseases based on different biological components. The application of electrochemical microfluidic chips for cTnI was also briefly introduced in this review. Finally, this review also briefly discusses the unresolved challenges of electrochemical detection and the expectations for improvement in the detection of cTnI biosensing in the future.

"Dual Signal-On" Split-Type Aptasensor for TNF-α: Integrating MQDs/ZIF-8@ZnO NR Arrays with MB-Liposome-Mediated Signal Amplification

Ultrasensitive and accurate detection of biomarkers in serum is of great importance for disease diagnosis and treatment. So far, the commonly used single-mode signal suffers from certain instinct drawbacks that restrict assay performances. Herein, we report the proof-of-concept fabrication of a split-type photoelectrochemical (PEC) and electrochemical (EC) dual-modal aptasensor for ultrasensitively tracing tumor necrosis factor-α, a noteworthy biological biomarker with essential clinical importance. By smart integrating molybdenum disulfide QDs/zeolitic imidazolate framework-8@ZnO nanorod arrays with a methylene blue-liposome-mediated signal amplification strategy, "dual signal-on" detection is accomplished based on a sandwich reaction of the target with aptamer-anchored carboxyl magnetic beads and an aptamer-confined MB liposome. Linear ranges of 5 fg/mL-5 μg/mL (detection limit 1.46 fg/mL) for PEC and 10 fg/mL-0.5 μg/mL (detection limit 6.14 fg/mL) for EC are obtained, respectively. An independent signal transduction mechanism supports the accuracy improvement, and a separate biological process from a translator enables convenient fabrication, short-time consumption, wider linearity, as well as outstanding reproducibility and stability in practical application. This work presents a universal bioassay route with prospects in biomedical and related areas.

Recent Advances in Aptamer Sensors

Recently, aptamers have attracted attention in the biosensing field as signal recognition elements because of their high binding affinity toward specific targets such as proteins, cells, small molecules, and even metal ions, antibodies for which are difficult to obtain. Aptamers are single oligonucleotides generated by in vitro selection mechanisms via the systematic evolution of ligand exponential enrichment (SELEX) process. In addition to their high binding affinity, aptamers can be easily functionalized and engineered, providing several signaling modes such as colorimetric, fluorometric, and electrochemical, in what are known as aptasensors. In this review, recent advances in aptasensors as powerful biosensor probes that could be used in different fields, including environmental monitoring, clinical diagnosis, and drug monitoring, are described. Advances in aptamer-based colorimetric, fluorometric, and electrochemical aptasensing with their advantages and disadvantages are summarized and critically discussed. Additionally, future prospects are pointed out to facilitate the development of aptasensor technology for different targets.