A new sandwich-type electrochemiluminescence sensor based on HPSNs-NH2@Au NPs and AuPdPt NPs for determination of α(2,3)-sial-Gs

A novel sandwich-type "on-off" electrochemiluminescence (ECL) biosensor for the determination of α(2,3)-sial-Gs was designed. Specifically, amino-functionalized porous silica nanoparticles (HPSNs-NH2) were first prepared and then decorated with gold nanoparticles (Au NPs) to form HPSNs-NH2@Au NP nanocomposite, which exhibited a strong ability to enhance ECL intensity with K2S2O8 as co-reactant (signal-on) and could immobilize the target-specific binding molecules of maackia amurensis lectin (MAL). Additionally, AuPdPt trimetallic nanoparticles were prepared to serve as a quenched ECL signal indicator (signal-off) with the ability of capturing the target non-specific binding molecules of 3-aminophenylboronic acid (APBA) to form a signal label. The sandwich-type ECL biosensor was constructed based on the structure of MAL-α(2,3)-sial-Gs-APBA and achieved a determination toward α(2,3)-sial-Gs with a wide linear range from 1 fg mL-1 to 10 ng mL-1 and a low detection limit of 0.5 fg mL-1. Furthermore, the proposed ECL biosensor showed satisfactory selectivity, stability, and reproducibility for α(2,3)-sial-Gs determination.

Lys-AuNPs@MoS2 Nanocomposite Self-Assembled Microfluidic Immunoassay Biochip for Ultrasensitive Detection of Multiplex Biomarkers for Cardiovascular Diseases

The progression of cardiovascular diseases is accompanied by myocardial injury and necrosis, heart failure, and inflammatory response. Accordingly, ultrasensitive and rapid detection of multiple biomarkers plays a vital role in clinical diagnosis and timely treatment. Here, we developed a novel Lys-AuNPs@MoS₂ nanocomposite self-assembled microfluidic immunoassay biochip with digital signal output and applied it to the simultaneous detection of multiple serum biomarkers including inflammatory factors and cardiovascular biomarkers, PCT, CRP, IL6, cTnI, cTnT, and NT-BNP, with high throughput and sensitivity. The digital output signal was collected in the solid phase on the chip surface with two-dimensional distribution of targets. Lys-AuNPs@MoS₂ nanocomposites self-assembled biochips could simultaneously detect all six biomarkers in 60 samples in 40 min with detection limit of a few to tens of pg/mL for all serum biomarkers. The microfluidic biochip based on Lys-AuNPs@MoS₂ nanocomposites provides a promising method in applications for clinical diagnosis.

Fabrication strategies and surface tuning of hierarchical gold nanostructures for electrochemical detection and removal of toxic pollutants

The intensive research on the synthesis and characterization of gold (Au) nanostructures has been extensively documented over the last decades. These investigations allow the researchers to understand the relationships between the intrinsic properties of Au nanostructures such as particle size, shape, morphology, and composition to synthesize the Au nano/hybrid nanostructures with novel physicochemical properties. By tuning the properties above, these nanostructures are extensively employed to detect and remove trace amounts of toxic pollutants from the environment. This review attempts to document the achievements and current progress in Au-based nanostructures, general synthetic and fabrication strategies and their utilization in electrochemical sensing and environmental remediation applications. Additionally, the applications of Au nanostructures (e.g., as adsorbents, sensing platforms, catalysts, and electrodes) and advancements in the field of electrochemical sensing of different target analytes (e.g., proteins, nucleic acids, heavy metals, small molecules, and antigens) are summarized. The literature survey concludes the existing methods for the detection of toxic contaminants at various concentration levels. Finally, the existing challenges and future research directions on electrochemical sensing and degradation of toxic contaminants using Au nanostructures are defined.

Application of the catalytic activity of gold nanoparticles for development of optical aptasensors

Biosensor technology is considered to be a great alternative in analytical techniques over the conventional methods. Among many recently developed techniques and devices, aptasensors are interesting because of their high specificity, selectivity and sensitivity. Combining aptamer as a biological recognition element with gold nanoparticles (AuNPs) as probe, are becoming more general owing to their beneficial properties, including low cost and ability to analyze specific targets on-site and using naked eye. Hydrogen bonds, nucleic acid hybridization, aptamer-target and antigen-antibody binding, Raman signature, enzyme inhibition, and enzyme-mimicking activity are main different sensing strategies exploited in AuNPs-based optical aptasensors. In this review article, we discussed the recent advances in optical aptasensors with a special emphasis on the catalytic activity property of AuNPs.

Electrogenerated chemiluminescence of Ru(bpy)32+ at MoS2 nanosheets modified electrode and its application in the sensitive detection of dopamine

Electrogenerated chemiluminescence (ECL) of Ru(bpy)₃²⁺ was studied at a MoS₂ nanosheets modified glassy carbon electrode (MoS₂NS/GCE) in neutral condition. Electrochemical results revealed that MoS₂ nanosheets could significantly catalyze the electrochemical oxidation of Ru(bpy)₃²⁺, as a result, strong anodic ECL was obtained. Several impact factors, such as the modified amount of MoS₂ nanosheets suspension, the pH value, and the concentration of Ru(bpy)₃²⁺, were investigated to obtain the optimal experimental condition. Dopamine exhibited apparent inhibiting effect on ECL intensity of Ru(bpy)₃²⁺-MoS₂ nanosheets through energy transfer process, and could be sensitively detected in the range of 1.0 × 10^-9 to 1.0 × 10^-4 mol L^-1. The linear equation between the decrease of ECL intensity and the logthium of dopamine concentration was determined as ΔI = 9965.02 + 1077.03lgC (C in mol L^-1), with the detection of 8.5 × 10^-10 mol L^-1 (3σ). The modified electrode exhibited satisfactory sensitivity, selectivity, and stability, which can be used to detect dopamine in real samples.

One-Step Synthesis of Tunable Zinc-Based Nanohybrids as an Ultrasensitive DNA Signal Amplification Platform

Herein, we demonstrated a one-step route for the manufacturing of polypyrrole (PPy)/zinc nanohybrids with tunable elemental composition and nanoscale component mixing resolution by using an ultrafast (within tens of seconds) microwave approach for ultrasensitive DNA biosensors. The zinc-based nanoparticles (i.e., MWPPy/ZnO and MWPPy/ZnS) were produced by loading zinc acetate (ZnAc₂) on PPy under the electromagnetic environment of a microwave with or without sulfur powder in one pot. Then, the signal amplification platforms were fabricated by modifying the glassy carbon electrode (GCE) with the obtained nanohybrids. It was found that both of the resultant MWPPy/ZnO and MWPPy/ZnS were suitable for ultrasensitive DNA molecule detection of the gastric carcinoma related PIK3CA gene ascribing to their unique hybrid nanostructures and surface characteristics. Experimental results revealed that the proposed GCE/MWPPy/ZnO sensor showed a linear range of 1.0 × 10^-10 to 1.0 × 10^-13 M. Notably, the GCE/MWPPy/ZnS sensor was endowed with promising DNA hybrid selection with a minimum concentration response of 1.0 × 10^-18 M. The corresponding detection limit was, respectively, found to be 2.90 × 10^-11 and 7.73 × 10^-21 M for MWPPy/ZnO- and MWPPy/ZnS-based biosensors. Furthermore, reliable determination of single-base and two-base mismatched DNA are more attractive, which greatly supported the application of the constructed zinc-based nanohybrids for the detection of single nucleotide polymorphism in genetic diseases, biological infectious pathogens, or warning against bio-warfare agents.

Tunable electrochemiluminescence properties of CsPbBr3perovskite nanocrystals using mixed-monovalent cations

Herein, we demonstrate a simple approach for tuning the elecrochemiluminescence (ECL) properties of CsPbBr₃perovskite nanocrystals by using mixed-monovalent cations.

Highly sensitive detection for cocaine using an aptamer–cocaine–aptamer method

In this study, a thiol-modified aptamer was immobilized on a gold nanoparticle-modified molybdenum disulfide composite material (MoS₂@AuNPs), which could remove the interference of physical adsorption and reduce false positive signals.

Highly sensitive determination of DNA via a new type of electrochemical zirconium signaling probe

Exploiting Zr(iv) as a redox probe for the detection of DNA has great potential in clinical analysis.

Magnetic Graphene Field-Effect Transistor Biosensor for Single-Strand DNA Detection

Herein, a magnetic graphene field-effect transistor biosensor was prepared through the transfer of a chemical vapor deposition graphene film onto a glass substrate to produce a sensing film and conductive channel. By fixing 1-pyrenebutanoic acid succinimidyl ester onto graphene film as an anchor, a probe aptamer was immobilized on the graphene film in order to capture magnetically labeled complementary single-stranded DNA. Our experiments showed that, within a periodic magnetic field, the biosensor impedance exhibited a periodic oscillation, the amplitude of which was correlated to the complementary DNA concentration. Based on this principle, the magnetic graphene field-effect transistor was utilized to detect single-stranded DNA with detection limition of 1 pM. The results were rationalized using a model wherein the magnetic force causes the DNA strand to bend, thereby resulting in magnetic nanobeads/DNA modulation of the double conductive layer of graphene transistors. Furthermore, since a periodic magnetic field could be introduced to produce a periodic impedance changes of MGFETs, sampling integration could be used to improve the signal-to-noise ratio efficiently by increasing the number of periods of the external magnetic field. Therefore, a novel biosensor for DNA detection with high sensitivity has been presented in this work. Based on the detection principle, this system may also be a potential tool for detecting other bio-molecules, cells, etc.

Recent advances in molybdenum disulfide-based electrode materials for electroanalytical applications

The primary objective of this review article is to summarize the development and structural diversity of 2D/3D molybdenum disulfide (MoS₂) based modified electrodes for electrochemical sensors and biosensor applications. Hydrothermal, mechanical, and ultrasonic techniques and solution-based exfoliation have been used to synthesize graphene-like 2D MoS₂ layers. The unique physicochemical properties of MoS₂ and its nanocomposites, including high mechanical strength, high carrier transport, large surface area, excellent electrical conductivity, and rapid electron transport rate, render them useful as efficient transducers in various electrochemical applications. The present review summarizes 2D/3D MoS₂-based nanomaterials as an electrochemical platform for the detection and analysis of various biomolecules (e.g., neurotransmitters, NADH, glucose, antibiotics, DNA, proteins, and bacteria) and hazardous chemicals (e.g., heavy metal ions, organic compounds, and pesticides). The substantial improvements that have been achieved in the performance of enzyme-based amperometry, chemiluminescence, and nucleic acid sensors incorporating MoS₂-based chemically modified electrodes are also addressed. We also summarize key sensor parameters such as limits of detection (LODs), sensitivity, selectivity, response time, and durability, as well as real applications of the sensing systems in the environmental, pharmaceutical, chemical, industrial, and food analysis fields. Finally, the remaining challenges in designing MoS₂ nanostructures suitable for electroanalytical applications are outlined. Graphical abstract • MoS₂ based materials exhibit high conductivity and improved electrochemical performance with great potential as a sensing electrode. • The role of MoS₂ nanocomposite films and their detection strategies were reviewed. • Biomarkers detection for disease identification and respective clinical treatments were discussed. • Future Challenges, as well as possible research development for "MoS₂ nanocomposites", are suggested.

A method for SNP detection using MoS2@AuNPs and SYBR Green I in combination with enzyme digestion

Single-nucleotide polymorphisms (SNPs) in a gene sequence are markers for a variety of human diseases.

A comprehensive review on nano-molybdenum disulfide/DNA interfaces as emerging biosensing platforms

The development of nucleic acid-based portable platforms for the real-time analysis of diseases has attracted considerable scientific and commercial interest. Recently, 2D layered molybdenum sulfide (2D MoS₂ from here on) nanosheets have shown great potential for the development of next-generation platforms for efficient signal transduction. Through combination with DNA as a biorecognition medium, MoS₂ nanostructures have opened new opportunities to design and construct highly sensitive, specific, and commercially viable sensing devices. The use of specific short ssDNA sequences like aptamers has been proven to bind well with the unique transduction properties of 2D MoS₂ nanosheets to realize aptasensing devices. Such sensors can be operated on the principles of fluorescence, electro-cheumuluminescence, and electrochemistry with many advantageous features (e.g., robust biointerfacing through various conjugation chemistries, facile sensor assembly, high stability with regard to temperature/pH, and high affinity to target). This review encompasses the state of the art information on various design tactics and working principles of MoS₂/DNA sensor technology which is emerging as one of the most sought-after and valuable fields with the advent of nucleic acid inspired devices. To help achieve a new milestone in biosensing applications, great potential of this emerging technique is described further with regard to sensitivity, specificity, operational convenience, and versatility.

Noble metal nanostructure-decorated molybdenum disulfide nanocomposites: synthesis and applications

Noble metal nanostructure-decorated MoS₂ nanocomposites have been used in sensors, catalysts, antibacterial materials and batteries due to their excellent properties.

Two-dimensional MoS2: A promising building block for biosensors

Recently, two-dimensional (2D) layered nanomaterials have trigged intensive interest due to the intriguing physicochemical properties that stem from a quantum size effect connected with their ultra-thin structure. In particular, 2D molybdenum disulfide (MoS₂), as an emerging class of stable inorganic graphene analogs with intrinsic finite bandgap, would possibly complement or even surpass graphene in electronics and optoelectronics fields. In this review, we first discuss the historical development of ultrathin 2D nanomaterials. Then, we are concerned with 2D MoS₂ including its structure-property relationships, synthesis methods, characterization for the layer thickness, and biosensor applications over the past five years. Thereinto, we are highlighting recent advances in 2D MoS₂-based biosensors, especially emphasize the preparation of sensing elements, roles of 2D MoS₂, and assay strategies. Finally, on the basis of the current achievements on 2D MoS₂ and other ultrathin layered nanomaterials, perspectives on the challenges and opportunities for the exploration of 2D MoS₂-based biosensors are put forward.

A simple label-free electrochemical DNA biosensor based on carbon nanotube–DNA interaction

A DNA biosensor based on π–π interactions between DNA and MWCNTs was developed in which the MWCNTs play the role of a conductive indicator.