Simultaneous analysis of catechol and hydroquinone by polymelamine/CNT with dual-template molecular imprinting technology

Molecularly imprinted photoelectrochemical sensor for ultrasensitive and selective detection of hydroquinone using 0D CdS nanoparticle/3D flower-like ZnIn2S4 microsphere nanocomposite

A novel photoelectrochemical (PEC) sensor was developed for the ultra-sensitive and highly selective detection of hydroquinone (HQ), featuring a composite structure that combines 0D CdS nanoparticles with a 3D flower-like ZnIn2S4 microsphere. The sensor, termed rMIP/CdS/ZnIn2S4, employed molecularly imprinted polymers (MIPs) to achieve specific recognition of HQ. An p-phenylenediamine (pPD) polymer film was electrochemically polymerized onto the surface of the CdS/ZnIn2S4 composite-coated glassy carbon electrode (GCE). Through hydrogen bonding, HQ molecules were imprinted onto the polymer film. Subsequent elution removed these molecules, leaving behind specific recognition sites, enabling selective detection of HQ. The unique spatial structure and heterojunction properties of the 0D CdS nanoparticle/3D flower-like ZnIn2S4 composite, combined with molecular imprinting, significantly enhanced the photocurrent response and increased the selectivity and sensitivity for HQ detection. Under optimal conditions, the rMIP/CdS/ZnIn2S4 sensor demonstrated a low detection limit (0.7 nmol·L-1, S/N=3) over a wide linear range of 1-1200 nmol·L-1. The sensor was successfully applied to detect HQ in real water samples, showing promise for environmental pollution control applications.

Redox probe-free electrochemical immunosensor utilizing electropolymerized melamine on reduced graphene oxide for the point-of-care diagnosis of gastric cancer

Pepsinogen I (PG I) is a biomarker that plays a crucial role in the diagnosis of gastric cancer. The development of biosensor to monitor PG I overexpression in serum is crucial for early gastric cancer diagnosis, offering a less invasive alternative to the costly and uncomfortable gastroscopy procedure. This study presents a cost-efficient, scalable and disposable label-free biosensing strategy for detecting PG I, utilizing a redox-active polymelamine electrodeposited on a reduced graphene oxide screen-printed electrode surface (PM-rGO/SPE). Under optimized conditions, the conducting polymer PM was deposited on the rGO/SPE via a potentiodynamic method. The structural and morphological features of PM-rGO/SPE were analyzed with the assistance of Raman and Scanning Electron Microscopy analysis. Specific monoclonal anti-PG I antibodies were immobilized on the in situ prepared redox-active layer via EDC/NHS chemistry to develop a novel electrochemical immunosensor. Unlike the traditional immunosensing strategies which utilizes external redox probe solution for measuring the signal, the developed configuration allowed for redox-probe free monitoring of current changes of the redox active PM resulting from the formation of the immunocomplex on the electrode surface. Utilizing this method, PG I detection spanned a clinically relevant concentration range of 0.01-200 ng/mL, with a low limit of detection at 9.1 pg/mL. The electrochemical immunosensor demonstrated specificity against other biomarkers such as PDCD1, ErBb2, and CD28 with negligible interference. The immunosensor exhibited excellent recovery capabilities for PG I detection in serum samples. These findings underscore the potential of the PM-rGO/SPE immunosensor as a point-of-care diagnostic tool for gastric cancer.

Nanomaterial-based Electrochemical Sensors for Multiplex Medicinal Applications

This review explores the advancements in nanomaterial-based electrochemical sensors for the multiplex detection of medicinal compounds. The growing demand for efficient and selective detection methods in the pharmaceutical field has prompted significant research into the development of electrochemical sensors employing nanomaterials. These materials, defined as functional materials with at least one dimension between 1 and 100 nanometers, encompass metal nanoparticles, polymers, carbon-based nanocomposites, and nano-bioprobes. These sensors are characterized by their enhanced sensitivity and selectivity, playing a crucial role in simultaneous detection and offering a comprehensive analysis of multiple medicinal complexes within a single sample. The review comprehensively examines the design, fabrication, and application of nanomaterial- based electrochemical sensors, focusing on their ability to achieve multiplex detection of various medicinal substances. Insights into the strategies and nanomaterials employed for enhancing sensor performance are discussed. Additionally, the review explores the challenges and future perspectives of this evolving field, highlighting the potential impact of nanomaterial-based electrochemical sensors on the advancement of medicinal detection technologies.

Bimetallic MOF synergy molecularly imprinted ratiometric electrochemical sensor based on MXene decorated with polythionine for ultra-sensitive sensing of catechol

Dual-signal ratiometric molecularly imprinted polymer (MIP) electrochemical sensors with bimetallic active sites and high-efficiency catalytic activity were fabricated for the sensing of catechol (CC) with high selectivity and sensitivity. The amino-functionalization bimetallic organic framework materials (Fe@Ti-MOF-NH₂), coupled with two-dimensional layered titanium carbide (MXene) co-modified glassy carbon electrode provides an expanded surface while amplifying the output signal through the electropolymerization immobilization of polythionine (pTHi) and MIP. The oxidation of CC and pTHi were presented as the response signal and the internal reference signal. The oxidation peak current at +0.42 V rose with increased concentration of CC, while the peak currents of pTHi at -0.20 V remained constant. Compared to the common single-signal sensing system, this one (MIP/pTHi/MXene/Fe@Ti-MOF-NH₂/GCE), a novel ratiometric MIP electrochemical sensor exhibited two segments wide dynamic range of 1.0-300 μM (R² = 0.9924) and 300-4000 μM (R² = 0.9912), as well as an ultralow detection limit of 0.54 μM (S/N = 3). Due to the specific recognition function of MIPs and the advantages of built-in correction of pTHi, the prepared surface imprinting sensor presented an excellent performance in selectivity and reproducibility. Besides, this sensor possessed superior anti-interference ability with ions and biomolecules, excellent reproducibility, repeatability, and acceptable stability. Furthermore, the proposed sensing system exhibits high specific recognition in the determination of environmental matrices and biological fluids in real samples with satisfactory results. Therefore, this signal-enhanced ratiometric MIP electrochemical sensing strategy can accurately and selectively analyze and detect other substances.