An extended-gate-type organic field effect transistor functionalized with molecularly imprinted polymer has shown chiral selectivity to l-histidine and discriminated it from amino acid families. Indeed, the chiral sensor device has simultaneously determined four points of the enantiomeric excesses of the chiral amino acid.

Biomarkers in body fluids provide essential chemical information for examining health conditions; however, unlike conventional instrumental approaches, easy-to-use analytical methods have not yet been fully established. This review introduces extended-gate-type organic field-effect transistors (OFETs) as biosensor platforms for real-sample analysis. OFETs are electronic devices that show switching profiles when gate voltages are applied. Therefore, the gate electrode of OFET functions as a sensing unit combined with appropriate molecular recognition materials. Owing to their signal amplification properties, OFETs enable sensitive biosensing. The extended-gate surfaces are easily functionalized with enzymatic layers using chemical modification, and these surfaces provide a high discrimination ability for specific biomarkers from their analogs. This review presents the designs of the extended-gate structures (i.e., integrated and separated styles) and their enzymatic layers and includes their actual sensing performance. © 2025. The Author(s).

Paper substrates have been widely used as chemical sensor platforms owing to their eco-friendliness and high processability. Conventional paper-based analytical devices allow single analyte detection, whereas real samples contain multiple analytes at wide concentration ranges. Although multi-sensing devices are required in real-world scenarios, the realization is still challenging. Motivated by this, the author has developed paper-based sensor array devices for multi-sensing. In this regard, cross-reactive optical sensors are appropriate elements to achieve both qualitative and quantitative detection based on pattern recognition. Such cross-reactive chemical sensors on an array show various optical responses on a paper substrate upon the addition of different analytes. The optical sensor elements can be uniformly printed on the paper substrate using office apparatuses. In addition, optical responses of the paper substrate embedded with cross-reactive sensors are rapidly detected using digital recorders, followed by data processing using imaging analysis and pattern recognition techniques. Therefore, paper-based sensor array devices allow not only the simultaneous detection of multiple chemical information but also accurate analysis comparable to stational analytical methods. Herein, the author shows appropriate designs of paper-based sensor array devices and their applicability for real-sample analysis. © 2025 SPIE.

A colorimetric chemosensor array based on an indicator displacement assay has achieved not only visualization of differences in hormone structures but also quantitative detection of sex hormones in their mixtures. Furthermore, the chemosensor array has allowed the detection of a steroid hormone in diluted human saliva.

Gold nanoparticles (AuNPs) have attractedthe interest of scientists owing to their unique applications in diverse fields. This study presents a report on the utilisation of glutaraldehyde (GA) as a reducing and stabilising agent for the one-pot preparation of AuNPs functionalised with GA (GA-AuNPs), designed specifically for the immobilisation of proteins. The preparation of stable GA-AuNPs has been systematically explored by varying the temperature, quantity of GAs, and pH. Subsequently, bovine serum albumin and horseradish peroxidase have been immobilised on the GA-AuNPs surface to demonstrate the versatility of GA-AuNPs. Dynamic light scattering results indicated that the prepared quasi-spherical GA-AuNPs exhibited a zeta potential of −31.2 ± 2.3 mV and had a size of 5.7 ± 0.5 nm. The advantages of this method include its simplicity at room temperature under approximately neutral pH conditions, elimination of the need for additional steps, and streamlining of the immobilisation process. These results emphasise that GA-AuNPs are promising candidates for effectively transporting proteins or enzymes across a diverse range of applications. © 2024 Vietnam Academy of Science & Technology.

Sensor arrays, which draw inspiration from the mammalian olfactory system, are fundamental concepts in high-throughput analysis based on pattern recognition. Although numerous optical sensor arrays for various targets in aqueous media have demonstrated their diverse applications in a wide range of research fields, practical device platforms for on-site analysis have not been satisfactorily established. The significant limitations of these sensor arrays lie in their solution-based platforms, which require stationary spectrophotometers to record the optical responses in chemical sensing. To address this, this review focuses on paper substrates as device components for solid-state sensor arrays. Paper-based sensor arrays (PSADs) embedded with multiple detection sites having cross-reactivity allow rapid and simultaneous chemical sensing using portable recording apparatuses and powerful data-processing techniques. The applicability of office printing technologies has promoted the realization of PSADs in real-world scenarios, including environmental monitoring, healthcare diagnostics, food safety, and other relevant fields. In this review, we discuss the methodologies of device fabrication and imaging analysis technologies for pattern recognition-driven chemical sensing in aqueous media. © 2024