An Electrochemical Sensor based on p-aminothiophenol/Au Nanoparticle-Decorated H TiS2 Nanosheets for Specific Detection of Picomolar Cu (II)

Microelectronic fibers for multiplexed sweat sensing

Wearable bioelectronics are gaining extraordinary attention due to their capabilities to achieve continuous monitoring of human health status. However, mainstream manufacturing technologies, including photolithography and printing technology, limit current wearable bioelectronics on 2D planar structures with little surface area in contact with the body. It thus limits the amount of physiological information that current wearable bioelectronics could obtain. Furthermore, they need to be firmly attached to the body, affecting the wearing comfort. In this study, we leveraged the versatile thermal drawing process and developed a flexible microelectronic fiber with bioanalytical functions that could be woven into textiles as a new form of wearable bioelectronics. Within a single strand of fiber, we successfully integrated all-in-one multiplexed electrochemical sensing capabilities, with the sweat as the primary object. Adopting the laser micromachining technique, we developed biosensing functions on the longitudinal surface of the fiber with two sensing electrodes for Na⁺ and uric acid (UA), respectively, together with a pseudo reference electrode (p-RE). We carefully characterized the all-in-one multiplexed sensing performance of the fiber and demonstrated its successful application in sweat sensing based on its textile forms. The results show significant potential for application in wearable textiles for monitoring key health signals of humans.

Two-dimensional inorganic nanosheets: production and utility in the development of novel electrochemical (bio)sensors and gas-sensing applications

This review (with 178 references) focuses on inorganic layered materials (ILMs) and the use of their two-dimensional nanosheets in the development of novel electrochemical (bio)sensors, analytical devices, and gas-phase sensing applications. The text is organized in three main sections including the presentation of the most important families of ILMs, a comprehensive outline of various "bottom-up", "top-down," and hydro(solvo)thermal methods that have been used for the production of ILM nanosheets, and finally an evaluative survey on their utility for the determination of analytes with interest in different sectors of contemporary analysis. Critical discussion on the effect of the production method on their electronic properties, the suitability of each nanomaterial in different sensing technologies along with an assessment of the performance of the (bio)sensors and devices that have been proposed within the last 5 years, is enclosed. The perspectives of further improving the utility of 2D inorganic nanosheets in sensing applications, in real-world samples, are also discussed.

Class-selective voltammetric determination of hydroxycinnamic acids structural analogs using a WS2/catechin-capped AuNPs/carbon black-based nanocomposite sensor

A high-performance screen-printed electrode (SPE) based nanocomposite sensor integrating tungsten disulfide (WS₂) flakes decorated with catechin-capped gold nanoparticles (AuNP-CT) and carbon black (CB) has been developed. The excellent antifouling properties of WS₂ decorated with AuNP-CT into a high conductivity network of CB results in high selectivity, sensitivity, and reproducibility for the simultaneous determination of hydroxycinnamic acid (hCN) structural analogs: caffeic (CF), sinapic (SP), and p-coumaric acids (CM). Using differential pulse voltammetry (DPV), the target hCNs resulted in three well-resolved oxidation peaks at SPE-CB-WS₂/AuNP-CT sensor. Excellent antifouling performance (RSD i_p,a ≤ 3%, n = 15 for three analytes' simultaneous measure) and low detection limits (CF 0.10 μmol L^-1; SP, 0.40 μmol L^-1; CM, 0.40 μmol L^-1) are obtained despite the analyzed compounds having a high passivation tendency towards carbon-based sensors. The SPE-CB-WS₂/AuNP-CT sensor was successfully applied to determine CF, SP, and CM in food samples with good precision (RSD ≤ 4%, n = 3) and recoveries (86-109%; RSD ≤ 5%, n = 3). The proposed sensor is the first example exploiting the simultaneous determination of these compounds in food samples. Given its excellent electrochemical performance, low cost, disposability, and ease of use, this SPE-CB-WS₂/AuNP-CT nanocomposite sensor represents a powerful candidate for the realization of electrochemical devices for the determination of (bio)compounds with high passivation tendency. Graphical abstract.

Covalent functionalization of MoS2 nanosheets synthesized by liquid phase exfoliation to construct electrochemical sensors for Cd (II) detection

Surface functionalization is an effective strategy in the precise control of electronic surface states of two-dimensional materials for promoting their applications. In this study, based on the strong coordination interaction between the transition-metal centers and N atoms, the surface functionalization of few-layer MoS₂ nanosheets was successfully prepared by liquid phase exfoliation method in N, N-dimethylformamide (DMF), 1-methyl-2-pyrrolidinone, and formamide. The cytotoxicity of surface-functionalized MoS₂ nanosheets was for the first time evaluated by the methylthiazolyldiphenyl-tetrazoliumbromide assays. An electrochemical sensor was constructed based on glass carbon electrode (GCE) modified by MoS₂ nanosheets obtained in DMF, which exhibits relatively higher sensitivity to Cd²⁺ detection and lower cytotoxicity against MCF-7 cells. The mechanisms of surface functionalization and selectively detecting Cd²⁺ were investigated by density functional theory calculations together with various spectroscopic measurements. It was found that surface-functionalized MoS₂ nanosheets could be generated through Mo-N covalent bonds due to the orbital hybridization between the 5 s orbitals of Mo atoms and the 2p orbitals of N atoms of the solvent molecules. The high selectivity of the sensor is attributed to the coordination reaction between Cd²⁺ and O donor atoms of DMF adsorbed on MoS₂ nanosheets. The robust anti-interference is ascribed to the strong binding energy of Cd²⁺ and O atoms of DMF. Under the optimum conditions, the electrochemical sensor exhibits highly sensitive and selective assaying of Cd²⁺ with a measured detection limit of 0.2 nM and a linear range from 2 nM to 20 μM.

Detection of Dopamine by a Biomimetic Electrochemical Sensor Based on Polythioaniline-Bridged Gold Nanoparticles

A new biomimetic electrochemical sensor was developed for the detection of dopamine based on a glassy carbon electrode modified with electrochemically generated gold nanoparticles. The preparation of the polymer is simple and cost-effective, achieving the polymerization of thioaniline and generation of gold nanoparticles in a single step by cyclic voltammetry, in the presence of the target molecule, dopamine. After extraction, the imprinted polymer exhibits high sensitivity and selectivity for dopamine. Moreover, the developed imprinted polymer film allows the fast, direct detection of dopamine without the need of a redox mediator. The formation of a self-assembled monolayer of the monomer prior to electropolymerization ensures the adherence of the film onto the electrode surface, conferring good stability to the sensor (over two weeks). Cyclic voltammetry, electrochemical impedance spectroscopy, atomic force microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy were used for the complete characterization of the developed sensor, and differential pulse voltammetry was used for its testing.

Carbon dots–quinoline derivative nanocomposite: facile synthesis and application as a “turn-off” fluorescent chemosensor for detection of Cu2+ ions in tap water

In this paper, a novel quinoline derivative: 8-(pyridin-2-ylmethoxy)quinoline-2-carboxylic acid (Q) has been successfully synthesized, then it was coupled with carbon dots (CDs) to synthesize a CDs–Q nanocomposite by a simple and green method.