Bimetallic-Doped Metal-Organic Gel for Efficient Electrochemiluminescence: Staircase-Mediated Energy Transfer and Applications in Epinephrine Detection.

This study presents the development of a novel bimetallic-doped metal-organic gel (Tb-Eu-MOG) synthesized by codoping terbium (Tb(III)) and europium (Eu(III)) with the Hcptpy ligand and explores its application in electrochemiluminescence (ECL) for sensitive detection of epinephrine (EP). The Tb-Eu-MOG exhibits unique petal nanoflower-like morphology and remarkable ECL signals, attributed to the dual sensitization effects of Tb(III) and Eu(III) on the Hcptpy ligand. The Tb(III) doping facilitates energy transfer and enhances ECL efficiency through a staircase effect.

Indicator-Free Detection of Hyaluronidase Based on a Conductivity-Regulated Bipolar Electrochemiluminescence Platform.

Hyaluronidase (HAase) detection plays a critical role in cancer diagnosis and treatment. Most HAase biosensors require the incorporation of exogenous indicators into the sensing reaction for signal transduction, which might involve complex synthesis and modification procedures or potentially interfere with enzymatic activity. Herein, based on the fact that the electrochemiluminescence (ECL) can be regulated via a bipolar electrode (BPE) through the alteration of conductivity in the enzymatic reaction solution, we develop an indicator-free HAase biosensor based on the bipolar-based ECL (BP-ECL) platform.

Amines-enriched vertically-ordered silica nanochannels for conductivity-regulated electrochemiluminescence sensing and bacterial metabolism detection.

An innovative amine-enriched vertically-ordered mesoporous silica film (VMSF) on indium tin oxide (ITO) electrodes (A-VMSF/ITO) utilizing an anionic template strategy was successfully developed, resulting in the inner walls of the nanochannel being adorned with well-ordered and abundant tertiary amine groups. In the context of A-VMSF/ITO, the elevated solution conductivity not only facilitates the permeation of Ru(bpy) within nanochannels by compressing the inner electric double layer (EDL), but also greatly improves the electron-transfer efficiency that is critical for enhanced electrochemiluminescence (ECL) generation. Therefore, the A-VMSF/ITO platform exhibited a consistent increase in ECL intensity with rising ionic strength.

Bipolar Electrochemiluminescence Detection of Ampicillin Resistance Genes via HRCA-Mediated Precipitation-Induced Conductivity Modulation.

Antibiotic resistance genes pose a significant threat to public health, highlighting the urgent need for rapid and sensitive detection methods. In this study, a bipolar electrochemiluminescence (BPE-ECL) sensing strategy was developed for detecting ampicillin resistance genes (ARG) based on conductivity variation induced by the precipitation reaction from hyperbranched rolling circle amplification (HRCA). Initiated by ARG, HRCA generates ultralong DNA chains with pyrophosphate as a byproduct.

Ultrasensitive adsorptive stripping voltammetry-free electrochemical sensor for Cu based on its specific catalytic etching to cytosine-rich oligonucleotide templated silver nanoparticles.

The development of reliable and highly sensitive copper ions (Cu) detection technologies is crucial for both environmental conservation and health surveillance. To address the challenges associated with conventional adsorptive stripping voltammetry, such as potential matrix interference, lengthy pre-electrolysis times, and limited detection sensitivity, we herein introduce an innovative electrochemical sensing approach for Cu. This method utilizes the unique catalytic etching capability of Cu on cytosine-rich oligonucleotide (CRO)-templated silver nanoparticles (AgNPs).

Electrochemiluminescence Detecting and Imaging of Yeast Metabolism Indicated by Endogenetic Co-reactant.

Glycolysis, a pivotal step in yeast metabolism, plays an indispensable role as a carbohydrate utilization process crucial for cellular survival. Developing advanced technologies to elucidate this fundamental physiological process holds significant scientific implications. Electrochemiluminescence (ECL) imaging exhibits the advantage of negligible background interference and facilitates straightforward visualization, thereby conferring significant value in biomolecular observation.

Electrophoresis-driven AIE luminogens encapsulated within silica isoporous membrane for acid vapor sensing.

Acid vapors emitted by chemical industries pose an increasing threat to public health. The development of a cost-effective sensor for the on-site and real-time monitoring of environmental acid vapor is of great significance. Aggregation-induced emission (AIE) luminogens overcome the aggregation-caused quenching effect and exhibit intense fluorescence when supported in the solid matrices.

Electrolytic growth of phenyl-modified silica isoporous membrane for non-polar extraction and electrochemical detection of pentachloronitrobenzene.

A phenyl-modified silica isoporous membrane (Ph-SIM) was prepared on the indium-tin-oxide (ITO) electrode using the electrochemically assisted self-assembly (EASA) method. The resulting Ph-SIM preserved vertically ordered nanochannels while exhibiting outstanding hydrophobicity due to the incorporation of phenyl groups within the nanochannels. As a result, the Ph-SIM/ITO sensor exhibited a remarkable affinity for PCNB extraction through hydrophobic interactions, leading to high detection sensitivity.

Copper(II)-Tannic Acid@Cu with In Situ Grown Gold Nanoparticles as a Bifunctional Matrix for Facile Construction of Label-Free and Ultrasensitive Electrochemical cTnI Immunosensor.

Sensitive detection of cardiac troponin I (cTnI) is of great significance in the diagnosis of a fatal acute myocardial infarction. A redox-active nanocomposite of copper(II)-tannic acid@Cu (CuTA@Cu) was herein prepared on the surface of a glassy carbon electrode by electrochemical deposition of metallic copper combined with a metal stripping strategy. Then, HAuCl was in situ reduced to gold nanoparticles (AuNPs) by strong reductive catechol groups in the TA ligand.

Conductivity-Regulated Bipolar Electrochemiluminescence Sensing Platform for Indicator-Free Homogeneous Bioassay.

Electrochemiluminescence (ECL) sensors have been widely developed because of their high sensitivity and low background. However, most of them suffered from tedious probe modification on the electrode and cross-interferences within the sensing and reporting reactions. The bipolar electrode based ECL (BPE-ECL) can effectively eliminate interference by physically separating the sensing and reporting cells, but there is still a need for exogenous electroactive indicators to transduce the variations between two poles of a BPE.

One-Pot Synthesis of Nanoflower-Like ZnSnS as Nanozymes for Highly Sensitive Electrochemical Detection of HO Released by Living Cells.

The sensitive and reliable nanozyme-based sensor enables the detection of low concentrations of HO in biological microenvironments, it has potential applications as an in-situ monitoring platform for cellular HO release. The uniformly dispersed bimetallic sulfide (ZnSnS) nanoflowers were synthesized via a one-pot hydrothermal method and the two kinds of metal ions can serve as morphology and structure directing agents for each other in the synthetic process. The nanoparticles were utilized as nanozyme materials to fabricate a novel electrochemical sensor, and it exhibits a distinct electrochemical response towards HO with excellent stability and detection capability (with a minimum detection limit of 1.

Electrophoretic deposition of Ru(bpy) in vertically-ordered silica nanochannels: A solid-state electrochemiluminescence sensor for prolidase assay.

Prolidase (PLD) plays a crucial role as a dipeptidase in various physiological processes, specifically involved in the cleavage of proline-containing dipeptides for efficient recycling of proline. The accurate determination of PLD activity holds significant importance in clinical diagnosis. Herein, a solid-state electrochemiluminescence (ECL) biosensor was developed to address the urgent need for PLD assay.

Competitive substitution in europium metal-organic gel for signal-on electrochemiluminescence detection of dipicolinic acid.

Metal-organic gels (MOGs) emerged as an attractive luminescent soft material for electrochemiluminescence (ECL). In this work, a cathodic ECL-activated europium metal-organic gel (Eu-MOG) has been synthesized by a facile mixing of Eu with 4'-(4-carboxyphenyl)-2,2':6',2''-terpyridine (Hcptpy) under mild conditions. The prepared Eu-MOG is highly mesoporous for co-reactant permeation to produce an ultra-stable and high-efficient ECL, based on the antenna effect of Eu coordinating with Hcptpy.

Metal-enhanced fluorometric formaldehyde assay based on the use of in-situ grown silver nanoparticles on silica-encapsulated carbon dots.

Fluorescent nanoparticles were prepared by encapsulating carbon dots (CDs) within silica spheres and then modifying these spheres with amino groups (CD@SiO-NH). On the basis of the silver mirror reaction, Ag assembled on the surface of CD@SiO-NH is reduced to silver nanoparticles (AgNPs) by formaldehyde. The in-situ grown AgNPs cause a visually distinguishable fluorescence enhancement.

Homogeneous Electrochemiluminescence Biosensor for the Detection of RNase A Activity and Its Inhibitor.

Ribonuclease A (RNase A) is increasingly considered as a biomarker for tumor diagnosis, and it is of great significance to develop an ultrasensitive, cost-effective assay for RNase A detection. Electrochemiluminescence (ECL) technology has distinctive advantages in the development of biosensors for diverse targets. However, most of the ECL biosensors require the complex process of electrode modification, which is laborious and time consuming.

A planar and uncharged copper(II)-picolinic acid chelate: Its intercalation to duplex DNA by experimental and theoretical studies and electrochemical sensing application.

Using an external redox-active molecule as a DNA hybridization indicator is still a popular strategy in electrochemical DNA biosensors because it is label-free and the multi-site binding can enhance the response signal. A planar and uncharged transition metal complex, Cu(PA) (PA = picolinic acid) with excellent electrochemical activity has been synthesized and its interaction with double-stranded DNA (dsDNA) is studied by experimental electrochemical methods and theoretical molecular docking technology. The experimental results reveal that the copper complex interacts with dsDNA via specific intercalation, which is verified by the molecular docking result.

Homogeneous and label-free electrochemiluminescence aptasensor based on the difference of electrostatic interaction and exonuclease-assisted target recycling amplification.

The difference of electrostatic interaction between free Ru(phen) and Ru(phen) embedded in double strand DNA (dsDNA) to the negatively charged indium tin oxide (ITO) electrode has been applied to develop a homogeneous and label-free electrochemiluminescence (ECL) aptasensor for the first time. Ochratoxin A (OTA) has been chosen as the model target. The OTA aptamer is first hybridized with its complementary single strand DNA (ssDNA) to form dsDNA and then interacted with Ru(phen) via the grooves binding mode to form dsDNA-Ru(phen) complex, which remains negatively charged feature as well as low diffusion capacity to the negatively charged ITO electrode surface owing to the electrostatic repulsion.

Cationic Carbon Dots for Modification-Free Detection of Hyaluronidase via an Electrostatic-Controlled Ratiometric Fluorescence Assay.

Carbon dots (CDs) emerge as excellent fluorescent nanomaterials, but the full exploitation and application of their exceptional properties in the development of fluorescence assay are still rare. In this work, cationic carbon dots (C-CDs) covered with plenty of positive charges on the surface were synthesized through a facile ultrasonic method. Negatively charged hyaluronic acid (HA) caused the aggregation of positively charged C-CDs and neutral red (NR) along its linear chain via electrostatic adsorption, leading to a remarkable Förster resonance energy transfer (FRET) from C-CDs to NR.

Graphene Oxide Directed One-Step Synthesis of Flowerlike Graphene@HKUST-1 for Enzyme-Free Detection of Hydrogen Peroxide in Biological Samples.

A novel metal-organic framework (MOF)-based electroactive nanocomposite containing graphene fragments and HKUST-1 was synthesized via a facile one-step solvothermal method using graphene oxide (GO), benzene-1,3,5-tricarboxylic acid (BTC), and copper nitrate (Cu(NO)) as the raw materials. The morphology and structure characterization revealed that the GO could induce the transformation of HKUST-1 from octahedral structure to the hierarchical flower shape as an effective structure-directing agent. Also, it is interesting to find out that the GO was torn into small fragments to participate in the formation of HKUST-1 and then transformed into the reduction form during the solvothermal reaction process, which dramatically increased the surface area, electronic conductivity, and redox-activity of the material.

Immobilization free electrochemical biosensor for folate receptor in cancer cells based on terminal protection.

The determination of folate receptor (FR) that over expressed in vast quantity of cancerous cells frequently is significant for the clinical diagnosis and treatment of cancers. Many DNA-based electrochemical biosensors have been developed for FR detection with high selectivity and sensitivity, but most of them need complicated immobilization of DNA on the electrode surface firstly, which is tedious and therefore results in the poor reproducibility. In this study, a simple, sensitive, and selective electrochemical FR biosensor in cancer cells has been proposed, which combines the advantages of the convenient immobilization-free homogeneous indium tin oxide (ITO)-based electrochemical detection strategy and the high selectivity of the terminal protection of small molecule linked DNA.

Facile construction of a highly sensitive DNA biosensor by in-situ assembly of electro-active tags on hairpin-structured probe fragment.

An ultrasensitive DNA biosensor has been developed through in-situ labeling of electroactive melamine-Cu(2+) complex (Mel-Cu(2+)) on the end of hairpin-like probe using gold nanoparticles (AuNPs) as the signal amplification platform. The 3'-thiolated hairpin-like probe was first immobilized to the gold electrode surface by the Au-S bond. The AuNPs were then tethered on the free 5'-end of the immobilized probe via the special affinity between Au and the modified -NH2.

A sensitive DNA biosensor based on a facile sulfamide coupling reaction for capture probe immobilization.

A novel DNA biosensor was fabricated through a facile sulfamide coupling reaction. First, the versatile sulfonic dye molecule of 1-amino-2-naphthol-4-sulfonate (AN-SO3(-)) was electrodeposited on the surface of a glassy carbon electrode (GCE) to form a steady and ordered AN-SO3(-) layer. Then the amino-terminated capture probe was covalently grafted to the surface of SO3(-)-AN deposited GCE through the sulfamide coupling reaction between the amino groups in the probe DNA and the sulfonic groups in the AN-SO3(-).

Carbon dots and chitosan composite film based biosensor for the sensitive and selective determination of dopamine.

A simple, sensitive and reliable dopamine (DA) biosensor was developed based on a carbon dots (CDs) and chitosan (CS) composite film modified glassy carbon electrode (CDs-CS/GCE). Under optimal conditions, the CDs-CS/GCE showed a better electrochemical response for the detection of DA than that of the glassy carbon electrode (GCE). The oxidation peak current (Ipa) of DA was linear with the concentration of DA in the range from 0.

Low-background, highly sensitive DNA biosensor by using an electrically neutral cobalt(II) complex as the redox hybridization indicator.

An electrically neutral cobalt complex, [Co(GA)2(phen)] (GA = glycollic acid, phen = 1,10-phenathroline), was synthesized and its interactions with double-stranded DNA (dsDNA) were studied by using electrochemical methods on a glassy carbon electrode (GCE). We found that [Co(GA)2(phen)] could intercalate into the DNA duplex through the planar phen ligand with a high binding constant of 6.2(±0.