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Fatal pathogenic organisms have been detected by various point‐of‐care tests (PoCTs) in clinical samples. PoCTs based on portable electrical devices are able to detect organisms in simple and rapid method. Although electrical PoCT devices show ultra sensitivity when detecting pathogens in standard samples, their industrialization has been limited due to low reproducibility, sensitivity, and specificity, resulting from nonspecific binding issues by media. In this research, a perpendicular N‐heterocyclic carbene self‐assembled monolayer (NHC‐SAM) conjugated on graphene micropattern field‐effect transistors (NGMFETs) is first demonstrated for monitoring pathogens. Two single bonds of NHCSAM on GM are investigated via density functional theory (DFT) and surface analyses. Bioreceptors are conjugated on the side gate‐modulated NGMFET for ultra‐stable on‐site detection. The side‐gated BNGMFETs system displayed remarkable performance in the detection of the following: i) SARS‐CoV‐2 spike protein S1 (limit of detection (LOD): ≈10 pg mL−1) in CTM, ii) O. tsutsugamushi Ab (LOD: ≈1 pg mL−1), and iii) E. coli (LOD: 10° CFU mL−1) in serum. Compared to commercial methodology, the platform presents 102 times higher LODs towards those pathogens in clinical samples with higher reproducibility. Based on these results, side‐gated BNGMFETs can be utilized as universal PoCT during pandemics. [ABSTRACT FROM AUTHOR]

Organic interfacial compounds (OICs) are required as linkers for the highly stable and efficient immobilization of bioprobes in nanobiosensors using 2D nanomaterials such as graphene. Herein, we first demonstrated the fabrication of a field‐effect transistor (FET) via a microelectromechanical system process after covalent functionalization on large‐scale graphene by introducing oligo(phenylene‐ethynylene)amine (OPE). OPE was compared to various OICs by density functional theory simulations and was confirmed to have a higher binding energy with graphene and a lower band gap than other OICs. OPE can improve the immobilization efficiency of a bioprobe by forming a self‐assembly monolayer via anion‐based reaction. Using this technology, Magainin I‐conjugated OGMFET (MOGMFET) showed a high sensitivity, high selectivity, with a limit of detection of 100 cfu mL−1. These results indicate that the OPE OIC can be applied for stable and comfortable interfacing technology for biosensor fabrication. [ABSTRACT FROM AUTHOR]

Hydrogels consisting of three-dimensional (3D) polymeric networks have found a wide range of applications in biotechnology due to their large water capacity, high biocompatibility, and facile functional versatility. The hydrogels with stimulus-responsive swelling properties have been particularly instrumental to realizing signal transduction in biosensors and bioelectronics. Graphenes are two-dimensional (2D) nanomaterials with unprecedented physical, optical, and electronic properties and have also found many applications in biosensors and bioelectronics. These two classes of materials present complementary strengths and limitations which, when effectively coupled, can result in significant synergism in their electrical, mechanical, and biocompatible properties. This report reviews recent advances made with hydrogel and graphene materials for the development of high-performance bioelectronics devices. The report focuses on the interesting intersection of these materials wherein 2D graphenes are hybridized with 3D hydrogels to develop the next generation biosensors and bioelectronics. [ABSTRACT FROM AUTHOR]

Abstract: In this study, we examined the in vitro electrochemical detection of Vascular Endothelial Growth Factor (VEGF) as cancer biomarker using p-type field-effect transistor (FET) biosensor. We demonstrated the high-performance FET sensor, which could detect ca. 400 fM of VEGF concentration, based on anti-VEGF RNA aptamer conjugated carboxylated polypyrrole nanotubes (CPNTs). The CPNTs used as high-performance transducers of this FET system were successfully fabricated by cylindrical micelle templates in a water-in-oil emulsion system. The functional carboxyl group (–COOH) was effectively incorporated into the polymer backbone during the polymerization by using pyrrole-3-carboxylic acid (P3CA) as a co-monomer. Two types of CPNTs (CPNT1: ca. 200 nm in diameter, CPNT2: ca. 120 nm in diameter) demonstrated the excellent conductivity performance in this FET system. Based on CPNTs conjugated with anti-VEGF RNA aptamer (CPNTs-aptamer), VEGF (target molecule) acts as the gate dielectrics of p-type FET sensor and specifically interacts with anti-VEGF aptamer attached to CPNT surfaces. Importantly, the VEGF detection limit of the FET sensor based on CPNT2-aptamer was found to be near 400 fM in real-time. Moreover, the CPNTs-aptamer FET sensors can be repeatedly used for various concentrations of the target molecule (VEGFs) through the washing and rinsing processes. [Copyright &y& Elsevier]

Abstract: A rapid and efficient strategy to detect novel heat shock protein 90 (Hsp90) inhibitors as anti-cancer agents was developed with field-effect transistor (FET) sensor based on carboxylated polypyrrole nanotubes (CPNTs). First of all, the CPNTs were successfully fabricated by using cylindrical micelle templates in a water-in-oil emulsion system, and the functional carboxyl groups were effectively incorporated into the polymer backbone during the polymerization by using pyrrole-3-carboxylic acid (P3CA) as a co-monomer. A liquid-ion gated FET-type sensor was readily constructed on the basis of CPNTs as the conductive channel. The CPNTs were covalently immobilized onto the microelectrode substrate to maintain stable electrical contact between the CPNTs and the microelectrodes in the liquid phase. Subsequently, Hsp90 was attached to the CPNTs surface through condensation reactions between the terminal amino groups in Hsp90 amino acid residues and the carboxyl groups on the CPNTs. The Hsp90-conjugated CPNT FET sensor provided a convenient and sensitive method to observe the affinity between Hsp90 to Hsp90 inhibitors in real-time. This result suggests that the FET sensor will open up the potential application for new anti-cancer drug discovery (Hsp90 inhibitors) after a judicious optimization. [Copyright &y& Elsevier]

Hydrogen sulfide is a critical biological messenger, but few biologically compatible methods are available for its detection in vivo. Here, we describe the design and synthesis of a novel azide-functionalized near-infrared probe, NIR-Az, for a hydrogen sulfide assay in which a self-immolative linker is incorporated between the azide moiety and phenolic dihydroxanthene fluorophore from a cyanine dye. A large “turn-on” near-infrared fluorescence signal results from the reduction of the azide group of the fluorogenic moiety to an amine, in which the self-immolative linker also enhances the accessibility of NIR-Az to hydrogen sulfide. NIR-Az can select hydrogen sulfide from among 16 analytes, including cysteine, glutathione, and homocysteine. By exploiting the superior properties of NIR-Az, such as its good biocompatibility and rapid cell internalization, we successfully demonstrated its usefulness in monitoring both the concentration- and time-dependent variations of hydrogen sulfide in living cells and animals (detection limit less than 0.26 μM), thereby providing a powerful approach for probing hydrogen sulfide chemistry in biological systems. [ABSTRACT FROM AUTHOR]