A double-quenching paperclip ECL biosensing platform for ultrasensitive detection of antibiotic resistance genes (mecA) based on Ti3C2 MXene-Au NPs as a coreactant accelerator

Anti-interference detection of antibiotic resistance genes via tetrahedral DNA framework-velcro capturing Py-HOF@Ti3C2 MXene

Methicillin-resistant Staphylococcus aureus (MRSA) is rapidly spreading worldwide. Concurrently, numerous antibiotic resistance genes (ARGs) have escaped into complex natural environments, particularly in water environment. Among these, mecA is one of the most prevalent ARGs identified in MRSA. Consequently, the development of robust analytical methods for detecting ARGs is critically important. This study effectively designed and constructed a tetrahedral DNA framework array termed "Velcro". By initiating the catalytic hairpin assembly (CHA) of the target loop through mecA, the "stickiness" of Velcro is stimulated, enabling efficient capture of, the composite of hydrogen-bonded organic frameworks (HOFs) with aggregation-induced electrochemiluminescence (AIECL) activity and co-reaction accelerator Ti3C2 MXene (TCM). Concurrently, the stable DNA framework can effectively withstand various environmental interferences, including bacterial invasion and enzymatic degradation, thereby enabling the sensitive detection and analysis of antibiotic resistance genes in complex environments. The linear range of the proposed ECL Biosensor for ARGs (mecA) detection was 0.01 pM to 10 nM, with a detection limit of 2.3 fM. This research proposes a novel approach for tracing this new type of genetic contamination and holds significant reference value for the scientific application of antibiotics.

Ti3C2Tx/Au NPs/PPy ternary heterostructure-based intra-capacitive self-powered sensor for DEHP detection

Phthalate esters, particularly di(2-ethylhexyl) phthalate (DEHP), are widely used plasticizers found in various consumer products, posing significant environmental and health risks due to their endocrine-disrupting effects. In this study, a novel enzyme-free intra-capacitive biofuel cell self-powered sensor (ICBFC-SPS) was developed. The ICBFC-SPS integrated a ternary heterostructure-based capacitive anode and a cathode with a sensing interface into a single-chamber electrolytic cell. The ternary heterostructure based on Ti3C2Tx MXene with ultra-small Au NPs and polypyrrole (PPy) NPs was prepared to provide the efficient glucose oxidation and robust electron production. Furthermore, the charge storage capacity was significantly enhanced through a synergistic combination of the double-layer capacitor mechanism of Ti3C2Tx and the pseudocapacitive behavior of PPy. Additionally, the intercalation of PPy NPs expanded the interlayer spacing, promoting electrolyte ion diffusion and charge transfer. The ICBFC-SPS demonstrated exceptional sensitivity with a linear detection range from 0.05 to 100000 ng/L and a detection limit of 9.51 pg/L for the sensitive and selective detection of DEHP in complex environmental and biological samples. The ICBFC-SPS addresses the limitations of traditional methods by providing a self-powered, highly sensitive, and portable platform for rapid, on-site DEHP detection. This work underscores the potential of self-powered sensors as transformative tools for real-time environmental monitoring and public health protection.

Target-triggered dual suppression of self-enhanced ECL sensor for sensitive detection of l-Cysteine

l-Cysteine (L-Cys), one kind of aminothiol, ubiquitously exists in proteins and plays important roles in the food industry and biological processes. Herein, an electrochemiluminescence (ECL) sensor was constructed for the sensitive detection of L-Cys. As an ECL emitter, europium-porphyrin coordination polymer (Eu-PCP) was synthesized and subsequently modified with copper benzene-1,4-dicarboxylate (CuBDC) as a coreaction accelerator, which achieved high self-enhanced ECL responses. CuBDC on Eu-PCP was decomposed by the introduced L-Cys due to the coordination between Cu2+ and L-Cys, resulting in the decrease of ECL signal. Besides, L-Cys could consume the co-reactant of K2S2O8 to reduce the production of free radical SO4•-, further decrease ECL signal. Thus, this L-Cys coordination-driven decomposition of coreaction accelerator and consumption of co-reactant strategy was employed to doubly suppress the ECL signal for detecting L-Cys without additional recognition and amplification elements. The constructed ECL sensor exhibited a linear range of 1.0 × 10-10-5.0 × 10-5 mol/L with a limit of detection of 2.0 × 10-11 mol/L. This work has opened up new prospects for developing novel ECL sensing strategies in food safety monitoring and disease diagnosis.

Bionic learning in MXene-based actuators: An emerging frontier

Bionics offers valuable insights into the design and application of MXene-based soft actuators, which have garnered significant attention in the fields of flexible electronics and smart materials owing to their exceptional electrical conductivity, tunable interlayer spacing, and responsiveness to diverse external stimuli. This review begins with a comprehensive summary of the main response mechanisms of MXene-based soft actuators under various external stimuli. It presents a detailed analysis of the advantages and limitations of different actuation modes and discusses strategies for composite modification with other materials to enhance MXene performance under multi-stimulus conditions. Inspired by the sensory capabilities of animals and plants in nature, this work explores the potential for biomimetic design and identifies four key challenges for advancing the field: (1) the development of efficient and controllable material synthesis techniques, (2) the electrochemical stability and environmental robustness of devices, (3) the overall performance optimization of actuators, and (4) the nascent exploration of biomimetic learning mechanisms. Finally, future research directions are outlined, offering novel perspectives to promote the broader application of MXene-based soft actuators in biomimetic systems.

Enzyme-free biosensor for ultrasensitive detection of mecA gene utilizing electrochemically controlled atom transfer radical polymerization triggered by copper nanoflowers enriched on DNA polymers

Herein, an ultrasensitive electrochemical biosensor is constructed to detect mecA gene by utilizing electrochemically controlled atom transfer radical polymerization (eATRP) triggered by copper nanoflowers enriched on DNA polymers. Firstly, specific capture and enrichment of mecA gene is achieved by using magnetic separation system, effectively weakening the interference of the complex matrix. Next, enzyme-free hybridization chain reaction is triggered in the presence of mecA gene to form long DNA polymers containing numerous active sites for subsequent binding to streptavidin-copper hybrid nanoflowers (SA@Cu HNFs). Then, numerous Cu(I) afforded by the reduction and dissolution of collected SA@Cu HNFs, as catalysts and signal transduction modulators, are applied to promote the click reaction between azide-modified DNA probes on the electrode surfaces and propargyl 2-bromoisobutyrate. Finally, plentiful electroactive polymers are continually grown in situ via eATRP, significantly boosting the signal output. Under optimal conditions, the biosensor can detect mecA gene as low as 0.06 fM, with a linear range from 0.1 fM to 10 pM. Moreover, the biosensor is high selective, and suitable for mecA gene detection in actual environment and food samples. Due to its ultra-sensitivity and cost-effectiveness, the developed strategy can achieve other genes detection by simply substituting the recognition element of target.

Wavelength-Resolved Magnetic Multiplex Biosensor for Simultaneous and Ultrasensitive Detection of Pneumonia Pathogens via Catalytic Hairpin Assembly Strategy with Luminescent Iridium Complexes

Pneumonia is a prevalent acute respiratory infection and a major cause of mortality and hospitalization, and the urgent demand for a rapid, direct, and highly accurate diagnostic method capable of detecting both Streptococcus pneumoniae (S. pneumoniae) and Klebsiella pneumoniae (K. pneumoniae) arises from their prominent roles as the primary pathogens responsible for pneumonia. Herein, two luminescent iridium complexes with nonoverlapping photoluminescence spectra, iridium(III)-bis [4,6-(difluorophenyl)-pyridinato-N,C2'] picolinate (abbreviated as Ir-B) and bis (2-(3,5- dimethylphenyl) quinoline-C2,N') (acetylacetonato) iridium(III)) (abbreviated as Ir-R), were unprecedently proposed to construct a novel wavelength-resolved magnetic multiplex biosensor for simultaneous detection of S. pneumoniae and K. pneumoniae based on catalytic hairpin assembly (CHA) signal amplification strategy combined with dye-doped silica nanoparticles. Notably, the proposed wavelength-resolved multiplex biosensor not only exhibits a broad linear range from 50 pM to 10 nM but also demonstrates excellent recovery rates for S. pneumoniae (96.1-99.3%) and K. pneumoniae (94.8-101.5%) in real clinical samples, with corresponding relative standard deviation (RSD) values ranging from 2.57 to 3.15% for S. pneumoniae and 1.45 to 3.17% for K. pneumoniae. These favorable experimental outcomes undoubtedly offer a promising approach for the simultaneous detection of multiple pathogens in the future.

Target-promoted activation of DNAzyme walker for in situ assembly of hemin/G-quadruplex nanowires enable ultrasensitive and label-free electrochemical myocardial microRNA assay

The concentration elevation of myocardial microRNA (miRNA) biomarker is associated with the pathogenic process of acute myocardial infarction (AMI), and sensitive quantification of myocardial miRNA biomarker plays an important role for early AMI diagnosis and its treatment. In response, this work describes an ultrasensitive and non-label electrochemical biosensor for the assay of myocardial miRNA based on cascade signal amplifications integrated by DNAzyme walker and hemin/G-quadruplex nanowires. The DNAzyme walker is activated by presence of target miRNAs to move along the electrode surface to cyclically cleave the substrate hairpins to release G-quadruplex segments, which further trigger the in situ formation of many hemin/G-quadruplex nanowires. The large amounts of hemin intercalated into the DNA nanowires subsequently generate drastically magnified electrochemical current signals for highly sensitive label-free assay of myocardial miRNAs down to 15.7 fM within dynamic range of 100 fM to 10 nM. Such a biosensor also has high selectivity and can monitor myocardial miRNAs in diluted serums at low levels, providing a sensitive and reliable platform for diagnosing infarct-associated cardiovascular diseases.

Novel Efficient Selenium-Based D-π-A NIR Polymer Dots Anodic Electrochemiluminescence Emitter and Its Application in Simultaneous Detection of Two Pneumonia Pathogens with CdS Quantum Dots

Community-acquired pneumonia (CAP) is a major cause of death in children under 5 years old globally. With Streptococcus pneumoniae (S. pneumoniae) and Mycoplasma pneumoniae (M. pneumoniae) being the main pathogens linked to CAP that requires hospitalization, there is an urgent need for a straightforward, cost-efficient, and highly accurate diagnostic method for immediate and early detection of CAP. In this work, benzo[1,2-c;4,5-c']bis([1,2,5]thiadiazole) (BBT) as π-bridge spacer with the donor unit of poly(9,9-dioctylfluorene) (PF) and the acceptor unit of dithienylbenzoselenadiazole (DBS) has been successfully copolymerized to unprecedentedly prepare novel D-π-A selenium-based polymer dots with efficient NIR electrochemiluminescence (named as Se-Pdots in this work). Se-Pdots exclusively generated excellent anodic ECL in the two-component coreaction system comprising TPrA and K2S2O8. Moreover, a potential-resolved ECL biosensor to simultaneously detect S. pneumoniae and M. pneumoniae has also been successfully constructed based on this novel Se-based NIR Pdots as an anodic emitter with CdS QDs as a cathodic emitter. Under optimal conditions, the biosensor has a wide linear range for S. pneumoniae (10-15 to 10-9 M) and M. pneumoniae (10-15 to 10-9 M), with low detection limits for S. pneumoniae (0.56 fM) and M. pneumoniae (0.96 fM). The proposed ECL biosensor provides a simple, sensitive, and reliable method for the simultaneous detection of CAP pathogens in clinical applications.

Bis-tridentate Iridium(III) Complex with the N-Heterocyclic Carbene Ligand as a Novel Efficient Electrochemiluminescence Emitter for the Sandwich Immunoassay of the HHV-6A Virus

Human herpesvirus type 6A (HHV-6A) can cause a series of immune and neurological diseases, and the establishment of a sensitive biosensor for the rapid detection of HHV-6A is of great significance for public health and safety. Herein, a bis-tridentate iridium complex (BisLT-Ir-NHC) comprising the N-heterocyclic carbene (NHC) ligand as a novel kind of efficient ECL luminophore has been unprecedently reported. Based on its excellent ECL properties, a new sensitive ECL-based sandwich immunosensor to detect the HHV-6A virus was successfully constructed by encapsulating BisLT-Ir-NHC into silica nanoparticles and embellishing ECL sensing interface with MXene@Au-CS. Notably, the immunosensor illustrated in this work not only had a wide linear range of 102 to 107 cps/μL but also showed outstanding recoveries (98.33-105.11%) in real human serum with an RSD of 0.85-3.56%. Undoubtedly, these results demonstrated the significant potential of the bis-tridentate iridium(III) complex containing an NHC ligand in developing ECL-based sensitive analytical methods for virus detection and exploring novel kinds of efficient iridium-based ECL luminophores in the future.

Ultrasensitive Electrochemiluminescence Biosensor to Detect Ampicillin Resistance Gene (ARGAMP) Based on a Novel Near-Infrared Ruthenium Carbene Complex/TPrA/PEI Ternary ECL System

The establishment of rapid target identification and analysis methods for antibiotic resistance genes (ARGs) is urgently needed. In this study, we unprecedently designed a target-catalyzed hairpin assembly (CHA) electrochemiluminescent (ECL) biosensor for the ultrasensitive detection of ampicillin resistance genes (ARGAMP) based on a novel, efficient near-infrared ruthenium carbene complex/TPrA/PEI ternary ECL system with low oxidation potential. The ternary NIR-ECL system illustrated in this work displayed double ECL intensity in comparison with their corresponding traditional binary ECL system. The as-prepared ECL biosensor illustrated in this work demonstrates highly selective and sensitive determination of ARGAMP from 1 fM to 1 nM and a low detection limit of 0.23 fM. Importantly, it also exhibits good accuracy and stabilities to identify ARGAMP in plasmid and bacterial genome DNA, which demonstrates its excellent reliability and great potential in detecting ARGAMP in real environmental samples.