Electrochemiluminescence biosensor for miRNA-21 based on toehold-mediated strand displacement amplification with Ru(phen) loaded DNA nanoclews as signal tags.

A novel electrochemiluminescence (ECL) biosensor was developed for high sensitive and selective detection of miRNA-21 based on the efficient and specific toehold-mediated strand displacement (TMSD) amplification with Ru(phen) loaded DNA nanoclews (NCs-Ru(phen)) as signal tags. The stable DNA nanoclews, synthesized by a simple rolling circle amplification reaction, were employed to load with Ru(phen) efficiently as ECL signal tags to amplify the signals. As for TMSD, the substrate strand (Sub) was initially hybridized with P1 and P2 to form DNA duplex structures with a toehold 1.

Ultrasensitive and Portable Assay for Lead(II) Ions by Electronic Balance as a Readout.

Lead ions (Pb) cause harm to human health. Therefore, the development of fast, effective, and convenient sensors for Pb monitoring has received great attention. In this study, a portable method has been proposed for Pb detection using normal electronic balance as a readout.

Development of an Immunosensor Based on the Exothermic Reaction between HO and CaO Using a Common Thermometer as Readout.

Thermometers, one of the most commonly used instruments at home, are normally adapted to measure temperature directly with high accuracy but rarely adopted to act as readout in the biosensors. It is necessary to find some ways to establish a relationship between the concentration of the target and the temperature change. In this study, a common thermometer was used as readout to develop a convenient immunosensor.

An electrochemical sensor based on poly(procaterol hydrochloride)/carboxyl multi-walled carbon nanotube for the determination of bromhexine hydrochloride.

Poly(procaterol hydrochloride) (p-ProH) polymeric film was successfully deposited onto the carboxyl multi-walled carbon nanotube (CMWCNT) modified glass carbon electrode (GCE) to construct a p-ProH/CMWCNT composite modified GCE. Due to the synergistic effect of p-ProH and CMWCNT in the composite, the developed sensor can enormously enhance the oxidation peak current of bromhexine hydrochloride (BrH) at + 0.90 V.

Fluorometric determination of the activity of inorganic pyrophosphatase and its inhibitors by exploiting the peroxidase mimicking properties of a two-dimensional metal organic framework.

A copper(II)-based two-dimensional metal-organic framework with nanosheet structure (CuBDC NS) that possesses peroxidase (POx) mimicking activity was prepared. In the presence of hydrogen peroxide, the system catalyses the oxidation of terephthalic acid to a blue-fluorescent product (excitation = 315 nm; emission = 425 nm). Pyrophosphate has a very strong affinity for Cu ion and blocks the POx-mimicking activity of the CuBDC NS.

Electrochemiluminescent functional nucleic acids-based sensors for food analysis.

Foodborne contaminants widely exist in foods, which can lead to various foodborne diseases and food safety issues. The development of quick, sensitive and universal analytical approaches for foodborne contaminants is imperative. Electrochemiluminescent functional nucleic acids (ECL FNAs)-based sensors are a series of sensing devices using FNAs as the recognition elements and ECL as the transducer.

A calcium alginate sponge with embedded gold nanoparticles as a flexible SERS substrate for direct analysis of pollutant dyes.

A surface-enhanced Raman scattering (SERS) substrate with good flexibility and high water absorbing capacity is reported. It consists of a calcium alginate sponge incorporating gold nanoparticles. These are in close contact with the sponge without the need for amino or sulfhydryl modification.

Label-free sensitive luminescence biosensor for immunoglobulin G based on AgAu ethisterone cluster-estrogen receptor α aggregation and graphene.

A specific and label-free "on-off-on" luminescence biosensor based on a novel heterometallic cluster [AgAu(ethisterone)]-estrogen receptor α (AgAuEth-ERα) aggregation utilizing graphene oxide (GO) as a quencher to lead a small background signal was firstly constructed to detect immunoglobulin G (IgG) with a simple process and high selectivity. The efficient photoluminescent (PL) AgAuEth-ERα aggregation is strongly quenched by GO. In the presence of IgG, the PL of this system will be restored, and perceivable by human eyes under UV lamp excitation (365 nm).

Target-Induced Horseradish Peroxidase Deactivation for Multicolor Colorimetric Assay of Hydrogen Sulfide in Rat Brain Microdialysis.

Hydrogen sulfide (HS) is important for normal neural functions, which involves protecting neurons from oxidative stress and neuronal transmission modulation in brain. The detection of HS is significant for revealing its role in the diagnosis of various disease. In this study, a novel multicolor colorimetric assay based on the etching of gold nanorods (Au NRs) is proposed to evaluate HS level with the naked eye.

An ultrasensitive conformation-dependent colorimetric probe for the detection of mercury(II) using exonuclease III-assisted target recycling and gold nanoparticles.

An ultrasensitive conformation-dependent colorimetric assay has been developed for the detection of mercury(II) ions. It is based on the use of exonuclease III (Exo III)-assisted target recycling and gold nanoparticles (AuNPs). In the absence of Hg(II), the hairpin-shaped DNA probe (H-DNA) binds to AuNPs and stabilizes them in solutions of high ionic strength.

Highly sensitive colorimetric aptasensor for ochratoxin A detection based on enzyme-encapsulated liposome.

A simple, low-cost, and sensitive liposome-based colorimetric aptasensor has been developed to detect ochratoxin A (OTA). Specifically, a dumbbell-shaped probe was designed, including magnetic beads (MBs), double-stranded DNA (dsDNA), and enzyme-encapsulated liposome. The dsDNA formed by the hybridization between OTA aptamer and its complementary probe.

A Simple and Convenient Aptasensor for Protein Using an Electronic Balance as a Readout.

The electronic balance, one of the most common pieces of equipment in the laboratory, is normally used to directly measure the weight of a target with high accuracy. However, little attention has been paid to the extension of its applications. In this study, an electronic balance was used as a readout to develop a novel aptasensor for protein quantification for the first time.

Preparation of an Efficient Ratiometric Fluorescent Nanoprobe (m-CDs@[Ru(bpy)]) for Visual and Specific Detection of Hypochlorite on Site and in Living Cells.

Hypochlorite (ClO) is one of the most important reactive oxygen species (ROS), which plays an important role in sustaining human innate immunity during microbial invasion. Moreover, ClO is a powerful oxidizer for water treatment. The safety of drinking water is closely related to its content.

Highly sensitive aptamer based on electrochemiluminescence biosensor for label-free detection of bisphenol A.

Bisphenol A (BPA), a typical endocrine disruptor, is widely used as a key monomer in the packaging industry. Residual monomer can transfer from the package material to the food and thereby pose a risk to the health of the consumer, so determination of BPA migration is highly important for food safety control. In this study, a simple but sensitive electrochemiluminescence (ECL) biosensor, which combines the characteristics of high selectivity of an aptamer and high sensitivity of ECL, has been developed to detect BPA from package materials.

Detection of aflatoxin B in food samples based on target-responsive aptamer-cross-linked hydrogel using a handheld pH meter as readout.

Aflatoxin B (AFB) can cause great threat to human health, so the development of convenient and portable device for sensitive detection of AFB is highly desired. The portable pH meter has the characters of facile operation, low cost, and easy availability. Therefore, in this study, we investigate the applicability of utilizing a pH meter as the readout to develop a portable sensor for AFB.

Highly sensitive antibody-aptamer sensor for vascular endothelial growth factor based on hybridization chain reaction and pH meter/indicator.

Vascular endothelial growth factor (VEGF) is a crucial signaling protein for the tumor growth and metastasis, which is also acted as the biomarkers for various diseases. In this research, we fabricate an aptamer-antibody sensor for point-of-care test of VEGF. Firstly, target VEGF is captured by antibody immobilized on the microplate, and then binds with aptamer to form the sandwich structure.

Electrochemical investigation and determination of procaterol hydrochloride on poly(glutamic acid)/carboxyl functionalized multiwalled carbon nanotubes/polyvinyl alcohol modified glassy carbon electrode.

Poly(glutamic acid) (P-GLU)/carboxyl functionalized multiwalled carbon nanotubes (MWCNTs-COOH)/polyvinyl alcohol (PVA) modified glassy carbon electrode (GCE) has been successfully prepared and the electrochemical behavior of procaterol hydrochloride (ProH) was studied. The results show that the as-prepared modified electrode exhibits a good electrocatalytic property towards the oxidation of ProH in 0.2M phosphate buffer solution (PBS) (pH 6.

Boron nitride nanosheets as a platform for fluorescence sensing.

Hexagonal boron nitride nanosheets (BNNS), one kind of inorganic graphene analogue, exhibit high fluorescence quenching ability via the photo-induced electron transfer (PET) and different affinity toward single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA). As a proof of concept, the BNNS was first used as a sensing platform for the rapid detection of DNA and small molecules with high sensitivity and selectivity in this study. This strategy is versatile and quick fluorescence sensing of DNA and extensive DNA related analytes such as metal cations and small molecules.

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.

A Portable Immunosensor with Differential Pressure Gauges Readout for Alpha Fetoprotein Detection.

A portable, affordable and simple detector is requested in a "Point-of-Care-Testing" (POCT) system. In this study, we exploited the potentialities of Differential Pressure Gauge (DPG) to the orientation of POCT technology. Alpha fetoprotein (AFP) was chosen as a model analyte that could specifically recognized by its antigen, and a tiny outfits equipped with a DPG was employed as the signal readout.

Highly sensitive colorimetric immunosensor for influenza virus H5N1 based on enzyme-encapsulated liposome.

Development of simple but sensitive biosensor for influenza detection is highly important in immediate and effective clinical treatment. In this study, a sensitive colorimetric immunosensor which combines the advantages of high selectivity of immunoassay and simplicity of colorimetric detection has been developed to detect influenza virus H5N1 based on enzyme-encapsulated liposome. Biotin-tagged liposome encapsulated with large amount of horseradish peroxidase (HRP) was firstly synthesized.

Highly Uniform Gold Nanobipyramids for Ultrasensitive Colorimetric Detection of Influenza Virus.

Gold nanoparticles (AuNPs) have been frequently utilized for the construction of diverse colorimetric biosensors. Normally, AuNPs with sharp edges could have better sensitivity. However, the poor monodipersity of AuNPs with sharp edges seriously confines their utility for colorimetric biosensing.

An electrochemiluminescence biosensor for Kras mutations based on locked nucleic acid functionalized DNA walkers and hyperbranched rolling circle amplification.

Herein, an electrochemiluminescence (ECL) biosensor for ultrasensitive and specific detection of Kras mutant genes has been developed on the basis of the high discrimination capability of locked nucleic acid (LNA) and dual signal amplification techniques including DNA walkers and hyperbranched rolling circle amplification (HRCA).

High peroxidase-like activity of iron and nitrogen co-doped carbon dots and its application in immunosorbent assay.

Herein, iron and nitrogen co-doped carbon dots (Fe-N-CDs) were synthesized through a solvothermal method assisting with the microwave synthesis system for the first time. Multiple techniques were employed to characterize the properties of the obtained particles. The emphasis of current work was the confirmation of their intrinsic peroxidase activity due to the Fe doping, which is similar to natural ferriporphyrin.

Creating BHb-imprinted magnetic nanoparticles with multiple binding sites.

A kind of protein imprinted over magnetic FeO@Au multifunctional nanoparticles (NPs) with multiple binding sites was synthesized and investigated. Magnetic FeO@Au NPs as carrier materials were modified with 4-mercaptophenylboronic acid (MPBA) and mercaptopropionic acid (MPA) to introduce boronic acids and carboxyl groups. Using Bovine Hemoglobin (BHb) as a template, a polydopamine(PDA)-based molecular imprinted film was fabricated to produce a kind of magnetic molecularly imprinted nanoparticle (MMIP), possessing multiple binding sites with benzene-diol, amino groups, boronic acids and carboxyl groups.