Wulan Tri Wahyuni

Widespread use of organophosphate pesticides (OPPs) raises environmental, food safety, and public health concerns, and drives demand for rapid, sensitive, portable analytical technologies. We reviewed conductive polymer composite (CPC)-based electrochemical OPP sensors, focusing on the structure–performance relationships of representative polymers, polyaniline (PANI), polypyrrole (PPy), polythiophene (PTh), and poly(3,4-ethylenedioxythiophene) (PEDOT), and their hybrids with carbon nanomaterials, metal nanoparticles, metal oxides, MXenes, and metal–organic frameworks. We provided a critical comparison of conductive polymer systems, composite architectures, and enzymatic, molecularly imprinted polymer-based, and direct electrocatalytic sensing strategies, highlighting how material selection influences performance and applicability. Reported CPC-based sensors achieved limits of detection from micro- to femtomolar and successful application in real environmental and food samples; however, these results illustrate the capabilities achieved by selected high-performing reported platforms rather than the overall performance of CPC-based sensors. Despite these advances, reproducibility, long-term operational stability, matrix effects, sensor variability, and field implementation still limit deployment. We discussed future directions to address these challenges, including AI-assisted data analysis, standardised validation, portable field platforms, and sustainable fabrication. Rather than identifying a universally superior platform, this review emphasises rational material selection and composite design to guide CPC sensor development and translation for environmental monitoring and food safety applications.

Preeclampsia is a serious pregnancy complication associated with hypertension and endothelial dysfunction caused by impaired placental vascularization. Early detection is essential to reduce maternal and fetal risks. Placental growth factor (PlGF), a pro-angiogenic biomarker that decreases significantly in preeclampsia, is a promising target for early diagnosis. This study develops a gold-modified boron-doped diamond (BDD/Au) electrochemical aptasensor for sensitive and selective PlGF detection. An optimal aptamer is selected through 3D structure modeling and molecular docking, followed by electrode fabrication, aptamer immobilization, and characterization using SEM, XPS, CV, EIS, and DPV. The selected aptamer exhibits a docking score of -288.41 and a confidence score of 0.9155. The aptasensor shows a signal-off response, with current decreasing as PlGF concentration increases. It demonstrates excellent linearity (R² = 0.9952) over 1–10,000 fg/mL, with limits of detection of 2.10 fg/mL in PBS and 2.58 fg/mL in spiked human serum. Selectivity studies against various interfering species show 95.87% selectivity and 86.91% specificity toward PlGF, confirming specific aptamer–target recognition. These findings demonstrate that the BDD/Au aptasensor is a highly sensitive and selective platform with strong potential for early preeclampsia diagnosis.

The development of an efficient, cost‐effective, and earth‐abundant electrocatalyst for hydrogen production is essential for sustainable energy conversion. In this study, we report a f ‐MWCNT/Ti ₃ C ₂ MXene nanocomposite synthesized by the hydrothermal method to evaluate the electrocatalytic activity of hydrogen evolution reaction (HER) in alkaline media. The acid‐functionalized MWCNT was introduced onto Ti ₃ C ₂ MXene sheets to prevent agglomeration and restacking and to improve charge‐transfer kinetics, thereby enhancing active‐site exposure and electrochemical performance. A hybrid nanostructure demonstrates a synergistic effect in facilitating HER, exhibiting a low overpotential of 415 mV at a current density of 10 mA cm ⁻² and a small Tafel slope of 197 mV dec ⁻¹ , compared with the individual f ‐MWCNT and Ti ₃ C ₂ MXene components. The high double‐layer capacitance (8.03 mF cm ⁻² ), which directly indicates a high ECSA (200.83 cm ² ) and is supported by a small charge‐transfer resistance (9.76 Ω), indicates the nanocomposite's role in enhancing active surface area and interfacial charge transfer to improve HER activity. The durability test results also show the nanocomposite's efficient stability for 9000 s with no significant change in overpotential before and after chronoamperometry. These findings highlight the potential of f ‐MWCNT/Ti ₃ C ₂ MXene to improve the efficiency of renewable energy conversion.

Background and purpose: Dopamine and nicotinamide adenine dinucleotide (NADH) are key biomarkers associated with neurological and metabolic disorders. Developing rapid, low-cost, and portable detection platforms of these biomarkers is essential for a point-of-care diagnostic kit. In this work, we report a colorimetric sensing approach using paper-based microfluidic devices (µPADs) modified with graphene-supported palladium (G/Pd) and platinum (G/Pt) nanocatalysts to enhance detection performance. Experimental approach: Monolayer G/Pd and G/Pt nanocomposites were synthesized via a hydrothermal method with precursor concentrations ranging from 0.1 to 10 mM. The catalytic behaviour and metal-graphene interactions were further investigated using spin-polarized density functional theory (DFT) calculation (PHASE/0). Microfluidic paper-based analytical devices (µPADs) were laser-printed on commercial filter paper and folded into 3D origami structures. Colorimetric responses were quantified using red, green, blue (RGB) and hue, saturation, value (HSV) analysis, where time-dependent Euclidean distance in RGB colour space was used to assess the reaction kinetics. Key results: DFT results indicate that Pd and Pt clusters preferentially adopt a top-site configuration on graphene, facilitating interfacial charge redistri­bution and enhancing catalytic activity experimentally. Catalyst-modified µPADs significantly improve reaction kinetics, reducing detection time by up to 3.7× for dopamine and 2.5× for NADH compared to unmodified devices. G/Pt (10 mM) exhibits the best overall performance, achieving limits of detection of 0.16 µM for dopamine and 0.195 µM for NADH with good linearity (R2 = 0.91). G/Pd displays competitive sensitivity, particularly at lower precursor concentration. Conclusion: The findings highlight that optimizing catalyst morphology and interfacial electronic structure is more critical than minimizing activation energy for achieving high-performance colorimetric sensing. The resulting platform shows potential as a cost-effective and portable tool for the detection of clinically relevant biomarkers in point-of-care settings.

Ground clove bud adulteration with cheaper materials, such as clove stem and soil, poses a significant threat to spice quality and consumer trust. This study introduces a novel, alternative analytical method for the authentication and detection of adulteration in ground clove bud samples. The approach combines voltammetric fingerprinting using a multi-walled carbon nanotube-modified electrode with robust chemometric analysis. Cyclic voltammetry of clove bud samples revealed anodic peaks above +0.5 V and a smaller cathodic peak between +0.5 and −0.3 V vs. Ag/AgCl, suggesting the presence of electroactive compounds. Voltammograms were obtained for authentic clove bud samples sourced from three major Indonesian production regions (South Sulawesi, North Maluku, and East Java), showing varying redox peak intensities. Chemometric analysis, specifically Partial Least Squares Discriminant Analysis (PLS-DA), was successfully employed to differentiate clove bud samples by geographical origin, and Principal Component Analysis (PCA) was used to discriminate authentic clove bud samples from adulterants. Furthermore, Partial Least Squares Regression (PLSR) was utilized to quantify adulteration levels, predicting adulterant concentration (10–100% w/w) using electrochemical signal intensities. The PLSR method exhibited strong linearity between observed and predicted values, confirming its robustness. This proposed method offers a simple, portable, and practical approach for the quality control of ground clove bud. The combination of rapid voltammetric measurement and chemometric modelling provides a valuable and practical tool to prevent fraud and ensure the integrity of the spice trade.

In this work, an analytical approach combining voltammetric detection with chemometric analysis was developed to discriminate melamine and urea adulterants in milk products. The electrochemical measurement was performed using a glassy carbon electrode (GCE) modified with acid-functionalized multiwalled carbon nanotubes (f-MWCNTs), which served as the working electrode to obtain the voltammetric fingerprint. This electrode was used to measure the voltammetric response of fresh cow milk adulterated with melamine and urea in 0.1 M KCl as the electrolyte by employing cyclic voltammetry (CV). Based on this result, milk adulterated with melamine and urea displayed broad peaks in the potential range of 0.6–0.8 V versus Ag/AgCl, attributable to the electroactive components in the adulterants and the milk. Additionally, it was found that milk adulterated with melamine exhibited several reduction peaks in the potential range from −0.4 to 0 V versus Ag/AgCl, corresponding to the reduction reaction of components present in melamine. Further chemometric analysis, i.e., principal component analysis, effectively distinguishes cow milk adulterated with melamine and urea. Moreover, the discrimination between cow’s milk and its adulterants was successfully achieved using hierarchical cluster analysis, with the lowest melamine concentration detected at 0.24%. Quantitative estimates of milk adulterants were predicted using partial least-squares regression, as determined by root-mean-square error cross-validation (RMSECV), with melamine at 0.0755% and urea at 0.0064%. Therefore, this result demonstrates a promising, cost-effective analytical technique that can be further developed into a novel approach for detecting adulterants in dairy products for practical applications.

An MWCNT-COOH/Chitosan-modified GCE combined with voltammetry and chemometrics enables sensitive detection and discrimination of Java Long Pepper adulteration.