A simple one-step electrochemical deposition of bioinspired nanocomposite for the non-enzymatic detection of dopamine

A simple and cost-effective electrochemical synthesis of carbon-based nanomaterials for electrochemical biosensor is of great challenge these days. Our study describes a single-step electrochemical deposition strategy to prepare a nanocomposite of electrochemically reduced graphene oxide (ErGO), multi-walled carbon nanotubes (MWCNTs), and polypyrrole (PPy) in an aqueous solution of pH 7.0 for dopamine (DA) detection. The ErGO/MWCNTs/PPy nanocomposites show enhanced electrochemical performance due to the strong π–π* stacking interactions among ErGO, MWCNTs, and PPy. The efficient interaction of the nanocomposites is confirmed by evaluating its physical and electrochemical characteristics using field-emission scanning electron microscopy, Raman spectroscopy, electrochemical impedance spectroscopy, cyclic voltammetry, and amperometry. The deposited nanocomposites are highly stable on the substrates and possess high surface areas, which is vital to improve the sensitivity and selectivity for DA detection. The controlled deposition of the ErGO/MWCNTs/PPy nanocomposites can provide enhanced electrochemical detection of DA. The sensor demonstrates a short time response within 2 s and is a highly sensitive approach for DA detection with a dynamic linear range of 25–1000 nM (R2 = 0.999). The detection limit is estimated to be 2.3 nM, and the sensor sensitivity is calculated to be 8.96 μA μM−1 cm−2, with no distinct responses observed for other biological molecules.

A review on nanostructure-based mercury (II) detection and monitoring focusing on aptamer and oligonucleotide biosensors

Heavy metal ion pollution is a severe problem in environmental protection and especially in human health due to their bioaccumulation in organisms. Mercury (II) (Hg²⁺), even at low concentrations, can lead to DNA damage and give permanent harm to the central nervous system by easily passing through biological membranes. Therefore, sensitive detection and monitoring of Hg²⁺ is of particular interest with significant specificity. In this review, aptamer-based strategies in combination with nanostructures as well as several other strategies to solve addressed problems in sensor development for Hg²⁺ are discussed in detail. In particular, the analytical performance of different aptamer and oligonucleotide-based strategies using different signal improvement approaches based on nanoparticles were compared within each strategy and in between. Although quite a number of the suggested methodologies analyzed in this review fulfills the standard requirements, further development is still needed on real sample analysis and analytical performance parameters.

CeO₂ Nanorods Embedded in Ni(OH)₂ Matrix for the Non-Enzymatic Detection of Glucose

The electrode based on cerium oxide (CeO₂) nanorods embedded in nickel hydroxide (Ni(OH)₂) matrix were prepared and used for detecting glucose non-enzymatically. The materials were characterized by X-ray diffraction, transmission electron microscopy (TEM), and so on. The results indicate that the response of CeO₂/Ni(OH)₂ nanocomposite are significantly improved due to the synergetic effect between CeO₂ and Ni(OH)₂. The optimum CeO₂/Ni(OH)₂ nanocomposite electrode exhibits a detection range from 2 μM to 6.62 mM, a sensitivity of 594 μA mM-1 cm-2, an estimated detection limit of 1.13 μM, and a response time less than 5 s. In addition, this biosensor also shows good selectivity, long term stability, and accurate measurement in juice on sale.

Luminol and gold nanoparticle-co-precipitated reduced graphene oxide hybrids with long-persistent chemiluminescence for cholesterol detection

Luminol and AuNP dual-functionalized rGO hybrids (rGO/AuNP/luminol) have been synthesized to generate long-persistent chemiluminescence, which can be used as a chemiluminescent biosensing platform for the detection of cholesterol.

Colorimetric and fluorescence “turn-on” methods for the sensitive detection of bromelain using carbon dots functionalized gold nanoparticles as a dual probe

Carbon dots were functionalized on the surfaces of gold nanoparticles for the colorimetric and fluorescence detection of bromelain. The limit of detection for bromelain was 18.9 nM and 0.52 nM using UV-visible and fluorescence spectroscopy, respectively.

Synthesis of a novel and stable reduced graphene oxide/MOF hybrid nanocomposite and photocatalytic performance for the degradation of dyes

A simple and facile solvothermal method is developed for the preparation of a reduced graphene oxide/NH₂-MIL-125(Ti) (rGO–NMTi) hybrid nanocomposite photocatalyst with large specific surface area and thermal stability.

Mesoporous silica supported bimetallic Pd/Fe for enhanced dechlorination of tetrachloroethylene

Immobilization of Pd–Fe nanoparticles on mesoporous SiO₂microspheres increases the reactivity for tetrachloroethylene dechlorination and enhances the mobility and permeability forin situremediation of chlorinated hydrocarbons in porous media.