The tailoring of novel nanomaterials for sensitive glucose detection through a non-enzymatic mechanism is currently under intensive research. Here, we present a laser-induced graphene (LIG) electrode decorated with silver nanoparticles (AgNPs) as a catalytic element for the direct electrooxidation of glucose. The AgNPs were synthesized through cyclic voltammetry using LIG as a template, resulting in a porous tridimensional assembly with anchored nanostructures. The characterization corroborated the formation of LIG/AgNPs composite with distinctive peaks attributed to Ag₂O and AgO interaction with glucose. The proposed non-enzymatic sensors were successfully applied for non-enzymatic amperometric detection, exhibiting a linear range from 1 to 10 mM in the first peak (+0.7 V) and a narrow range from 1 to 2 mM with higher sensitivity of 52.2 mA/mM and improved LOD of 45 μM in the second peak (+0.55 V). The applicability of the LIG/AgNPs sensor was evaluated with spiked artificial saliva in a PoC format using a smartphone potentiostat, showing an average recovery rate of 91%. The analysis was performed in a portable, mobile, and low-cost fashion using a simulated non-invasive sample, with promising results in clinical ranges.

Although an enzymatic electrochemical biosensor is a major keystone in Diabetes Mellitus management, its replacement with a low-cost and stable non-enzymatic glucose sensor (NEGS) is of high interest to scientific and industrial fields. However, most NEGS for direct glucose electrooxidation (DGE) must be performed under extreme alkaline conditions, implying additional pretreatments before detection and a limited application for on-body, real-time monitoring. Thus, research on DGE in physiological conditions is fundamental to successfully translating the current NEGS into clinical applications. In physiological conditions, drawbacks such as low current, low selectivity, and poisoning appear due to the reduction of OH ions in neutral electrolytes and the presence of chloride ions in biofluids. Therefore, an increasing number of nanomaterials based on Pt, Au, and their nanocomposites have been proposed to improve the electrochemical performance. Additionally, transition metals such as Cu, Pd, Ni, or Co combined with high surface area supports have shown promising results in increasing catalytic sites for DGE. The molecular interaction of phenylboronic acid with glucose has also been demonstrated in neutral conditions. Overall, the present review summarizes the current strategies for DGE in physiological conditions and highlights the challenges still faced for further development of functional glucose NEGS.

Chemical sensing based on semiconducting metal oxides has been largely proposed for acetone sensing, although some major technical challenges such as high operating temperature still remain unsolved. This work presents the development of an electrochemical sensor based on nanostructured PANI/cellulose/WO₃composite for acetone detection at room temperature. The synthesized materials for sensor preparation were polyaniline (PANI) with a conductivity of 13.9 S/cm and tungsten trioxide (WO₃) in monoclinic phase doped with cellulose as carbon source. The synthesized materials were characterized by high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), cyclic voltammetry (CV), and Raman spectroscopy. The composite was applied for acetone detection in the range of 0 to 100 ppmv at room temperature with electrochemical impedance spectroscopy (EIS) for monitoring resistance changes proportional to acetone concentration. The developed sensor achieved a calculated limit of detection of 10 ppm andR2of 0.99415 with a RSD of 5% (n=3) at room temperature. According to these results, the developed sensor is suitable for acetone sensing at room temperatures without the major shortcomings of larger systems required by high operating temperatures.

In this research, a brush-like polyaniline (poly(2-acrylamide-2-methyl-1-propanesulfonate)-g-polyaniline)-b-poly(N-vinylcarbazole) (BL PAni) was developed as a strategy to overcome the limited processability and dedoping above pH 4 of conventional polyaniline (PAni). For the BL PAni synthesis, RAFT polymerization (homopolymer), RAFT-mediated surfactant-free emulsion polymerization (block copolymer), and interfacial oxidative polymerization were applied to graft the PAni chains. NMR and FT-IR spectroscopies were performed to confirm the structural elucidation of the reaction pathways, while the thermal properties were analyzed by TGA and DSC. Notably, the BL PAni presents absorption throughout the visible region and up to the near-infrared, showing dedoping resistance at up to 80 °C and at a neutral pH. The absorption range of the BL PAni, block copolymer, and homopolymer were studied by UV–Vis spectroscopy in solid-state and dispersion/solution, highlighting BL PAni and poly(anilinium 2-acrylamide-2-methyl-1-propanesulfonate)-b-poly(N-vinylcarbazole) (PAAMP-b-PVK) due to the π-stacking between the anilinium and carbazole groups. The cyclic voltammetry confirmed the persistence of electroactivity at a pH near 7.