Sensor based on redox conjugated poly(para-phenylene) for the simultaneous detection of dopamine, ascorbic acid, and uric acid in human serum sample

Biosensors for psychiatric biomarkers in mental health monitoring

Psychiatric disorders are associated with serve disturbances in cognition, emotional control, and/or behavior regulation, yet few routine clinical tools are available for the real-time evaluation and early-stage diagnosis of mental health. Abnormal levels of relevant biomarkers may imply biological, neurological, and developmental dysfunctions of psychiatric patients. Exploring biosensors that can provide rapid, in-situ, and real-time monitoring of psychiatric biomarkers is therefore vital for prevention, diagnosis, treatment, and prognosis of mental disorders. Recently, psychiatric biosensors with high sensitivity, selectivity, and reproducibility have been widely developed, which are mainly based on electrochemical and optical sensing technologies. This review presented psychiatric disorders with high morbidity, disability, and mortality, followed by describing pathophysiology in a biomarker-implying manner. The latest biosensors developed for the detection of representative psychiatric biomarkers (e.g., cortisol, dopamine, and serotonin) were comprehensively summarized and compared in their sensitivities, sensing technologies, applicable biological platforms, and integrative readouts. These well-developed biosensors are promising for facilitating the clinical utility and commercialization of point-of-care diagnostics. It is anticipated that mental healthcare could be gradually improved in multiple perspectives, ranging from innovations in psychiatric biosensors in terms of biometric elements, transducing principles, and flexible readouts, to the construction of 'Big-Data' networks utilized for sharing intractable psychiatric indicators and cases.

Review—Recent Progress in Graphene Based Modified Electrodes for Electrochemical Detection of Dopamine

Graphene and its derivatives have been widely used for the electrochemical detection of dopamine (DA) neurotransmitter, thanks to its high surface area and excellent conductivity. Modified graphene and graphene-based nanocomposites have shown improved catalytic activity towards DA detection. Various modification approaches have been taken, including heteroatom doping and association with other nanomaterials. This review summarizes and highlights the recent advances in graphene-based electrodes for the electrochemical detection of DA. It also aims to provide an overview of the advantages of using polymer as a linker platform to form graphene-based nanocomposites applied to electrochemical DA sensors.

Ti3C2Tx (MXene)/Pt nanoparticle electrode for the accurate detection of DA coexisting with AA and UA

Dopamine (DA), uric acid (UA) and ascorbic acid (AA) are biomolecules widely distributed in the human body and play an important role in many physiological processes. An abnormal concentration of them is associated with various diseases. Thus, the accurate and fast detection of them has been one of the major demands in the healthcare industry. In this study, we demonstrate that Ti₃C₂T_x/PtNP modified glassy carbon electrodes (GCEs) show a good electrochemical performance in the detection of DA and UA. However, there is no response signal to AA for either the CV or DPV curve due to the electrostatic repulsion between the negatively charged electrode surface and the negatively charged AA. Ti₃C₂T_x(MXene)/Pt nanoparticles (PtNPs) are prepared by etching Ti₃AlC₂(MAX) with HF and reducing H₂PtCl₆ with a NaBH₄ aqueous solution. The morphology of Ti₃C₂T_x/PtNPs is multilayered accordion-like Ti₃C₂T_x decorated with PtNPs with a diameter of 10-20 nm. Furthermore, it is found that the electrochemical detection of DA will be enhanced by AA. The electrochemical detection rule of AA enhanced DA can be expressed as follows: I_(DA+AA) = 0.011216C_AA + 0.039950C_DA + 1.1175(I_(DA+AA) is the peak current of DA coexisting with AA. C_AA is the concentration of AA. C_DA is the concentration of DA). This can be used as a calibration to correct the concentration of DA when AA and DA coexist. Notably, AA promotes the stability of the electrode because it cleans the oxidation products from the electrode surface in time. In addition, the sensor exhibits good reproducibility and satisfactory recovery results in a real sample.

Recent Advances in Layered Double Hydroxide-Based Electrochemical and Optical Sensors

Layered double hydroxides (LDHs) have attracted considerable attention as promising materials for electrochemical and optical sensors owing to their excellent catalytic properties, facile synthesis strategies, highly tunable morphology, and versatile hosting ability. LDH-based electrochemical sensors are affordable alternatives to traditional precious-metal-based sensors, as LDHs can be synthesized from abundant inorganic precursors. LDH-modified probes can directly catalyze or host catalytic compounds that facilitate analyte redox reactions, detected as changes in the probe's current, voltage, or resistance. The porous and lamellar structure of LDHs allows rapid analyte diffusion and abundant active sites for enhanced sensor sensitivity. LDHs can be composed of conductive materials such as reduced graphene oxide (rGO) or metal nanoparticles for improved catalytic activity and analyte selectivity. As optical sensors, LDHs provide a spacious, stable structure for synergistic guest-host interactions. LDHs can immobilize fluorophores, chemiluminescence reactants, and other spectroscopically active materials to reduce the aggregation and dissolution of the embedded sensor molecules, yielding enhanced optical responses and increased probe reusability. This review discusses standard LDH synthesis methods and overviews the different electrochemical and optical analysis techniques. Furthermore, the designs and modifications of exemplary LDHs and LDH composite materials are analyzed, focusing on the analytical performance of LDH-based sensors for key biomarkers and pollutants, including glucose, dopamine (DA), H2O2, metal ions, nitrogen-based toxins, and other organic compounds.

Murexide-derived in vitro electrochemical sensor for the simultaneous determination of neurochemicals

This work highlights the protocol employed for the simultaneous electroanalysis of tryptamine, serotonin and dopamine using a conducting poly-murexide-based electrode. To date, this is the first-of-its-kind report of simultaneous electrochemical determination of these three targets. Features of the developed electrode were identified by employing FE-SEM analysis. Under optimized conditions, the analytes underwent an irreversible electro-oxidation at the modified electrode surface, with a linear range of 0.5-40 μΜ, 0.4-40.4 μΜ and 0.5-40 μΜ for dopamine, serotonin and tryptamine, respectively. The electrolytic medium employed for the sensing was a phosphate-buffered solution with pH 7. The specificity of the developed electrode was also satisfactory in the presence of other biomolecules including L-phenylalanine, L-serine, glucose and ascorbic acid. Thus, the developed murexide-derived conducting-polymer-based electrode was used for the simultaneous sensing of the neurochemicals dopamine, serotonin and tryptamine. Electroanalysis was also demonstrated for these targets in human serum.

Hemin-doped metal-organic frameworks based nanozyme electrochemical sensor with high stability and sensitivity for dopamine detection

This study reports a new type of artificial nanozyme based on Hemin-doped-HKUST-1 (HKUST-1, also referred to as MOF-199; a face-centered-cubic MOF containing nanochannels) as a redox mediator for the detection of dopamine (DA). Hemin-doped-HKUST-1 was successfully synthesized by one-pot hydrothermal method, which was combined with reduced graphene oxide (rGO) modified on a glassy carbon electrode (GCE) to construct a sensor (Hemin-doped HKUST-1/rGO/GCE). The morphology and structure of Hemin-doped-HKUST-1 were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and infrared spectra (IR) techniques. The Hemin-doped HKUST-1/rGO nanozyme showed an excellent electrocatalytic activity for DA oxidation, which is due to the enhanced Hemin activity through the formation of a metal-organic framework (MOFs) and the synergy between the Hemin-doped HKUST-1 and rGO in nanozyme. The resulted sensor exhibited a high sensitivity of 1.224 μA μM-1, with a lower detection limit of 3.27 × 10-8 M (S/N = 3) and a wide linear range of 0.03-10 μM for DA detection. In addition, due to the stabilizing effect of MOFs on heme, the sensor showed satisfactory stability and has been successfully applied to the detection of DA in serum samples, indicating that this work has potential value in clinical work.