Electrochemical Biosensor Based on Well-Dispersed Boron Nitride Colloidal Nanoparticles and DNA Aptamers for Ultrasensitive Detection of Carbendazim

Integration of a hamper pad on test strips for improved sensitivity of carbendazim detection

Lateral flow immunoassays (LFIAs) are widely used to determine carbendazim (CBZ) residues in food products due to their advantages of low cost, ease and rapid use, on-site detection capability. However, conventional LFIAs have low detection sensitivity. Although improvements have been made to increase the sensitivity, it is not sufficient. Here, a hamper pad, polyvinyl alcohol coated on a nitrocellulose membrane, was integrated to enhance the sensitivity of LFIA for CBZ detection. The hamper pad was inserted between the conjugated and nitrocellulose pads to delay the flow rate, thereby increasing the possibility of the antibody and target analyte binding. This platform exhibited a fourfold sensitivity increase in CBZ detection compared with the conventional LFIA, and its limit of detection was 1.6 ng/mL. In addition, a single-step operation was successfully applied to detect CBZ in rice (white rice, brown rice, sticky rice, and paddy) and soybean samples, with acceptable recoveries of 93.6%-120.0%. This novel device was compared to the standard high-performance liquid chromatography method, which shows high accuracy with a Kappa coefficient of 0.91. Therefore, improved sensitivity with a rapid, simple, and inexpensive device could facilitate the detection of CBZ residues in agricultural products for on-field screening and improved user-friendliness.

A dual action electrochemical molecularly imprinted aptasensor for ultra-trace detection of carbendazim

Carbendazim is often used in agriculture to prevent crop diseases, even though it has been associated with health concerns. To ensure the safety of food products and comply with environmental regulations, an ultrasensitive method for carbendazim determination must be developed. In this study, a new electrochemical molecularly imprinted polymer-aptasensor based on hemin-Al-metal organic framework@gold nanoparticles (H-Al-MOF@AuNPs) was developed for sensitive and selective carbendazim detection. Hemin linked to the surface of the Al-metal organic framework also possesses outstanding peroxidase-like qualities that can electrocatalyse the reduction of H2O2. Thus, H-Al-MOF functions as an in-situ probe. Additionally, AuNPs offer many binding sites to load carbendazim aptamers and create an imprinted polymer-aptasensing interface. Dopamine is the chemical functional monomer in the electropolymerised film, while carbendazim is the template molecule. Thus, compared to the molecularly imprinted polymer or aptasensor alone, the molecularly imprinted polymer-aptasensor showed greater selectivity due to the synergistic action of the polymer and carbendazim aptamer towards carbendazim. A decrease in peak current was observed by differential pulse voltammetry (DPV) and chronoamperometry (CA) as the concentration of carbendazim increased. This possibly resulted from carbendazim connecting to the carbendazim aptamer and simultaneously blocking the imprinted polymer cavities on the surface of the modified electrode, which reduced the transfer of electrons. Signals were observed for hemin DPV and H2O2 catalytic reduction CA. DPV and CA showed that the linear ranges for carbendazim were 0.3 fmol L-1-10 pmol L-1 and 0.7 fmol L-1-10 pmol L-1, respectively, with limits of detection of 80 and 300 amol L-1. Satisfactory recoveries were obtained with tap water, apple juice, and tomato juice samples, demonstrating that the proposed sensor has potential for food and environmental analysis.

Development of Two-Dimensional Functional Nanomaterials for Biosensor Applications: Opportunities, Challenges, and Future Prospects

New possibilities for the development of biosensors that are ready to be implemented in the field have emerged thanks to the recent progress of functional nanomaterials and the careful engineering of nanostructures. Two-dimensional (2D) nanomaterials have exceptional physical, chemical, highly anisotropic, chemically active, and mechanical capabilities due to their ultra-thin structures. The diversity of the high surface area, layered topologies, and porosity found in 2D nanomaterials makes them amenable to being engineered with surface characteristics that make it possible for targeted identification. By integrating the distinctive features of several varieties of nanostructures and employing them as scaffolds for bimolecular assemblies, biosensing platforms with improved reliability, selectivity, and sensitivity for the identification of a plethora of analytes can be developed. In this review, we compile a number of approaches to using 2D nanomaterials for biomolecule detection. Subsequently, we summarize the advantages and disadvantages of using 2D nanomaterials in biosensing. Finally, both the opportunities and the challenges that exist within this potentially fruitful subject are discussed. This review will assist readers in understanding the synthesis of 2D nanomaterials, their alteration by enzymes and composite materials, and the implementation of 2D material-based biosensors for efficient bioanalysis and disease diagnosis.

Tuberculosis detection from raw sputum samples using Au-electroplated screen-printed electrodes as E-DNA sensor

Tuberculosis (TB) remains a leading cause of death globally, especially in underdeveloped nations. The main impediment to TB eradication is a lack of efficient diagnostic tools for disease diagnosis. In this work, label free and ultrasensitive electrochemical DNA biosensor for detecting Mycobacterium tuberculosis has been developed based on the electrodeposition of gold nanoparticles on the surface of carbon screen-printed carbon electrode (Zensors) for signal amplification. Particularly, screen-printed electrodes were modified by electrochemical deposition of Au to enhance the conductivity and facilitate the immobilization of ssDNA probes via Au-S bonds. The electrochemically modified SPEs were characterized using Scanning electron microscopy/Energy Dispersive X-Ray Analysis (SEM/EDX) and X-Ray Diffraction (XRD). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques were used to investigate the DNA hybridization between single-stranded (ssDNA) probe and target DNA (tDNA). Under the ideal conditions, DPV exhibited a correlation coefficient R2 = 0.97, when analyzed with different tDNA concentrations. The proposed DNA biosensor exhibits a good detection range from 2 to 10 nm with a low detection limit of 1.91 nm, as well as high selectivity that, under ideal conditions, distinguishes non-complementary DNA from perfectly matched tDNA. By eliminating the need for DNA purification, this work paves the path for creating disposable biosensors capable of detecting DNA from raw sputum samples.