This study was focused on developing a process to objectively determine the release behavior of retronasal aromas in food in real time, which could contribute to the development of foods better suited to consumer preferences. In food, organic compounds with low molecular weight easily vaporize to elicit a retronasal aroma, and such compounds are referred to as volatile. In this study, the release of aroma during the eating of small sandwiches was measured and verified in real-time via resonance-enhanced multiphoton ionization time-of-flight mass spectrometry (REMPI-TOFMS). Cumin and small slices of bread were used as food samples that would easily vaporize and could be detected in the breath of a person eating them. Laser pulses emitting at 266 nm during REMPI selectively detected the naturally occurring organic compound p-cymene in cumin. While it was being chewed, the time profile for p-cymene as a retronasal aroma compound showed the increases and decreases in the detection of this food in breaths released in a 6 s cycle (3 s intake, 3 s exhalation). Overall, the retronasal aroma increased and then decreased. The total ion signals of p-cymene obtained during chewing (integrated area under the time profiles) were slightly smaller when eating 1 g of bread than when eating 3 or 7 g. The bread samples were mixed with saliva during chewing, and the oral cavity became relatively saliva-rich. In other words, the bread was easily converted to a liquid food, and the vaporization of the p-cymene in cumin seemed to be suppressed with smaller slices of bread. Moreover, a fit function for the obtained time profile was proposed in the present study. The profile was constructed by combining the subtracted values of the two logistic functions and a trigonometric function. As a fit result, the start and end times of the overall transient time profile were both earlier when eating 1 g of bread than when eating 3 or 7 g; the start time was numerically ca. 3 s earlier, and on average, p-cymene was found to be emitted from the nose half a breath earlier under the present eating conditions.
Seawater pH measurement is essential for monitoring ocean acidification and its biogeochemical impacts. Glass electrode pH sensors are widely used for in situ applications due to their ease of operation, low power consumption, and no reagent requirements. However, their accuracy can be affected by temperature-dependent effects, particularly those associated with the internal reference solution. Conventional calibration methods based on the Nernst response do not explicitly account for temperature-induced variations in the internal solution, which may lead to systematic bias under conditions with large temperature gradients. In this study, a correction method is proposed to address temperature-dependent errors by modeling the internal pH (pHin). The model incorporates two primary temperature-dependent contributions: the intrinsic temperature dependence of the phosphate buffer and potential shifts caused by activity changes in saturated KCl. These effects are combined through the electrode response factor (fR), defined as the ratio of the observed electrode slope to the theoretical Nernst slope, to estimate pHin as a function of temperature and correct measured pH values to a reference temperature of 25 °C. Application of the method to vertical seawater profiles demonstrated a reduction in deviation from colorimetric reference measurements. The corrected results showed reduced temperature-dependent bias across depth. This approach provides a practical framework for improving the reliability of in situ glass electrode pH measurements under varying thermal conditions. The proposed method addresses equilibrium temperature-dependent effects of the internal solution but does not explicitly account for transient hysteresis, pressure effects, or long-term sensor drift.
Osteoarthritis (OA) is a leading cause of chronic pain and disability in the elderly. The lack of sensitive diagnostic methods for early OA remains a major clinical challenge. Synovial fluid contains exosomes (SF-exosomes) that carry disease-specific biomolecules, making them promising targets for early diagnosis. However, efficient isolation of SF-exosomes with high purity is technically demanding. This study aimed to develop phosphatidylserine-based molecularly imprinted polymers (P-MIPs) for the efficient enrichment of SF-exosomes and to discover potential protein biomarkers for early OA diagnosis using proteomic analysis. P-MIPs can specifically recognize phosphatidylserine on the extracellular vesicle membrane, thereby achieving highly selective enrichment of extracellular vesicles. P-MIPs were synthesized via a reverse microemulsion system. The binding capacity, specificity, and enrichment efficiency of P-MIPs were characterized. SF-exosomes from 6 OA patients and 6 healthy controls were enriched using P-MIPs and analyzed by LC-MS/MS proteomics. Differentially expressed proteins (DEPs) were subjected to bioinformatics analysis. The diagnostic value of hub genes was validated by ROC analysis in an independent cohort. The results showed that the binding capacity (Qmax) of P-MIPs was 129.71 µmol/g, and the cross-reactivity with sphingomyelin (SM), phenylphosphonic acid (PYP), and tyrosine phosphopeptides was less than 3.5%. The purity of enriched SF-exosomes was 82.6%. A total of 40 DEPs were identified, of which 28 were upregulated and 12 were downregulated in OA. PPI network analyses identified 10 hub genes: IL6, IL1B, MYC, CD4, MMP9, PTPRC, CXCL8, PPARG, ICAM1, and STAT3. ROC analysis showed that among the top five hub genes ranked by degree, MYC (AUC = 0.741) and IL6 (AUC = 0.735) exhibited good diagnostic performance. A combined biomarker panel comprising the top five hub genes achieved an even higher diagnostic accuracy, with an AUC of 0.899. The P-MIPs-based SF-exosome enrichment strategy is efficient and selective. MYC and IL6 are potential diagnostic biomarkers for early OA, and the identified DEPs provide insights into OA pathogenesis. Furthermore, this strategy can be extended for the recognition and enrichment of exosomes in other biological fluid matrices, facilitating the discovery of novel disease biomarkers and therapeutic targets.
Serum C-terminal telopeptide of type I collagen (CTX-I) is a key bone turnover biomarker in osteoporosis, and its elevated levels are indicative of increased bone resorption. Current techniques for CTX-I measurement suffer from high operational requirements, complex procedures, and high costs. This study focuses on a novel strategy for detecting serum CTX-I concentration to predict the occurrence and severity of osteoporosis. Using silver-capped Fe3O4 (Fe3O4@Ag) as the substrate material, an artificial antibody for CTX-I was prepared via magnetic core-shell molecularly imprinted polymers (MIPs), and surface-enhanced Raman scattering (SERS) was used as a signal output device. With crystal violet (CV) at 10−4 M as the reporter molecule, the proposed biosensor exhibited a good linear response over the range of 10 pg/mL to 2 ng/mL (R2 = 0.986, LOQ = 4.79 pg/mL), covering the normal reference range required for identifying bone turnover. Moreover, the biosensing platform demonstrated resistance to matrix interference in real serum and urine samples. After six reuse cycles, the SERS intensity of CV decreased by only 10.5%, and after 15 days of storage at 4 °C, it decreased by 15.7%. The Fe3O4@Ag-MIPs were used to detect CTX-I with excellent uniformity (RSD = 4.1%) and repeatability (RSD = 2.7%), and the overall analysis time was 30 min. The proposed biosensing platform was applied to analyze known real serum samples obtained from human. The proposed biosensor was validated using enzyme-linked immunosorbent assay (ELISA), and the developed biosensor showed good correlation with ELISA. The experimental results indicate that the proposed novel biosensing platform is a fast, low-cost, and reliable tool for the rapid detection of the bone biomarker CTX-I in serum or urine.
Poly(dimethylsiloxane) (PDMS) is the most widely used material for microfluidic chips because of its advantageous properties including easy fabrication through soft lithography, which means pattern transfer technique from microfabricated master molds. However, most of the master molds are made of a silicon wafer and a photoresist layer, and have two major disadvantages: (1) the fabrication process is complicated and requires specialized facilities, and (2) the fabricated master molds are fragile. Here, we describe a simple fabrication technique to produce a robust master mold by pattern transfer from an existing PDMS chip to an inexpensive, hobby-use UV-curable resin (UV resin). The process requires no specialized facilities or hazardous chemicals. The test pattern consisted of microchannels with a cross-section of 100 µm × 25 µm and a total area of 30 mm × 30 mm. This pattern was faithfully transferred from the PDMS surface to the UV resin. The inaccuracy of the solidified UV resin was evaluated to be smaller than the measurement error (< 0.2%). The UV resin mold was subsequently tested for the soft lithography of a next-generation PDMS chip. For successful soft lithography, the UV resin mold required heat treatment at 60 °C for at least 48 h prior to use. Without this treatment, substantial damage was observed on both the PDMS and the UV resin surfaces. This problem was probably caused by the inhibition of PDMS curing due to unreacted components of the UV resin remaining on the surface. The technique presented here provides a simple and low-cost route for the repetitive fabrication of identical PDMS microfluidic chips for various research fields. [Image: see text] The online version contains supplementary material available at 10.1007/s44211-026-00920-2.
The thiol compounds present in wine 4-mercapto-4-methyl-2-pentanone (4MMP), 3-mercapto-1-hexanol (3MH), and 3-mercaptohexyl acetate (3MHA) are key components contributing to the aromatic characteristics of wines such as Sauvignon Blanc, giving muscat and blackcurrant notes. This study evaluated the effectiveness of surface-enhanced Raman spectroscopy (SERS) using silver-film over nanosphere (AgFON) substrate combined with immersion, static headspace, and dynamic headspace methods. The immersion method was found unsuitable for detection of target molecules in low concentrations due to interference from wine-derived components. In contrast, detection was difficult in the gas-phase conditions with the static headspace method, whereas the introduction of an acceptor phase under liquid-phase conditions facilitated spectral observation of the target compounds. Furthermore, the headspace method with dynamic control of the acceptor demonstrated the detectability of 4MMP, with characteristic spectral features observable at 10 nM under the examined experimental conditions. For 3MH and 3MHA, peaks overlapping with other wine components remained an issue. Principal component analysis (PCA) was applied as an exploratory tool to visualize spectral variance, and the results showed partial cluster overlap under certain conditions, while revealing trends that differentiate thiol-containing samples from wine-derived backgrounds. These results indicate that the headspace SERS approach using AgFON combined with an acceptor phase has potential for the detection of thiol compounds in wine, particularly for 4MMP.
A recurrent neural network (RNN) system based on a Hopfield neural network (HNN) was developed to extract essential spectral patterns from the time-of-flight secondary ion mass spectrometry (ToF-SIMS) spectra of peptide samples. Because ToF-SIMS produces various fragment ions from organic molecules, the interpretation of ToF-SIMS spectra is generally complicated. ToF-SIMS is useful for peptide analysis because it detects specific amino acid fragment ions from peptides that indicate peptide information. However, the ToF-SIMS spectra also contain fragment ions that do not preserve the main structures of the original molecules, which makes them difficult to interpret. Therefore, it is crucial to extract essential spectral patterns from the ToF-SIMS spectra of organic materials. Peptides were selected as the target organic materials for this study due to their systematic chemical structures. A modified HNN was trained on the ToF-SIMS spectra of each peptide, and the trained HNNs were then used to recall patterns for various peptide ToF-SIMS spectra. The results show that the modified HNN recall essential spectra containing specific ions, including the protonated molecular ions and amino acid fragment ions of target peptides. Furthermore, the HNN results revealed differences and similarities between peptides with similar and different amino acid sequences. Thus, this study demonstrates the effectiveness of the HNN in interpreting complex spectra and its potential for preprocessing data for further analysis.
The fluorescence quenching or turn-off strategy is an emerging method for determination of fluorescent and non-fluorescent active principal ingredients (API). It is gaining a growing interest in advanced pharmaceutical applications due to its high sensitivity and selectivity. The present review represents a comprehensive and up-to-date overview of the quantitative determination of drugs by fluorescence quenching-based methods with a special focus on probes for the first time. The theoretical fundamentals of fluorescence quenching, including static and dynamic quenching as well as the inner filter effect are presented. Subsequently, the key analytical and methodological considerations of fluorescence quenching-based methods, including analytical parameters (probe, solvent, pH), instrumentation, analytical performance with emphasis on application of green and white analytical chemistry principles, are highlighted. Finally, the properties of fluorescent probes (organic molecules, inorganic elements, salts, complexes, enzyme-catalyzed products, nanomaterials, nanocomposites, and hybrid materials) and their analytical approaches for drug determination are systematically appraised and summarized with relevant analytical conditions and parameters of the methods. The review also highlighted the advances and challenges of fluorescence quenching-based analytical methods.
Microdroplet injection systems, which introduce single cells into an inductively coupled plasma by encapsulating them in droplets, have been developed by several research groups, including our group. In our laboratory, to improve the analytical sensitivity, a droplet desolvation system using a ribbon heater has achieved an approximately tenfold improvement in sensitivity. However, the desolvation throughput was limited to 100 Hz because of the low heat-transfer efficiency associated with indirect of indirect heating via heated gas. In this paper, a novel desolvation device using infrared radiation was developed to improve the desolvation throughput. Infrared radiation enables direct and efficient droplet heating. The developed device comprises a heating section and a cooling section. An infrared lamp with a luminous length of 140 mm was used in the heating section. Infrared radiation was focused on the flight axis of the droplets to enhance irradiation efficiency. The cooling section was placed downstream of the heating section to condense and remove vapor. With a power of 1000 W applied to the lamp and a carrier gas flow rate of 0.1 L min-1, the carrier gas temperatures at the bottom of the heating section remained below 71 °C for both argon and helium. Under these conditions, the cells remained intact without rupture. Helium exhibited superior throughput compared to argon and when the carrier gas flow rate was above 0.5 L min-1, the desolvation at a throughput of 1000 Hz could be achieved with an applied power of 150 W to the lamp.
A portable microfluidic titration system using a smartphone camera was developed as a detector for onsite quantitative analysis. Two types of cross-shaped microfluidic devices with different channel geometries were designed and evaluated to improve the visual detectability of the equivalence point under limited spatial resolution. An expanding-channel device was found to promote molecular diffusion downstream, resulting in enhanced visibility of the equivalence point compared to a constant-width device. Using the optimized device, a strong acid-strong base system was subjected to acid-base titration using bromothymol blue as the indicator. The color images captured by the smartphone camera were analyzed by extracting the red channel intensity profiles and used to determine the distance corresponding to the equivalence point. A linear relationship was obtained between the measured distance and hydrochloric acid concentration in the range of 25-150 mM. The applicability of the proposed system was demonstrated by analyzing a real hot-spring water sample. The determined acid concentration was in good agreement with that obtained by conventional volumetric titration, with no statistically significant difference at the 95% confidence level. These results indicate that the proposed portable microfluidic titration system enables reliable quantitative analysis without the use of microscopes or specialized optical instruments, highlighting its potential for onsite analytical applications.
The Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method is widely used as a pretreatment technique to extract a broad range of drugs and toxicants into the acetonitrile layer. However, the aqueous layer generated during the extraction process has a high-salt content and has not been analytically explored. This study focused on the unused aqueous layer and established a method for detecting the highly polar compounds glyphosate (Gly) and glufosinate (Glu) through derivatization with 9-fluorenylmethoxycarbonyl chloride, followed by liquid chromatography–tandem mass spectrometry. Under optimized conditions, both analytes were effectively separated and detected with favorable peak shapes from 50 µL of whole blood. Calibration curves exhibited good linearity over the range of 0.1–10 µg/mL, with correlation coefficients of 0.993 for Gly and 0.994 for Glu. The lower limit of quantification for both compounds was 0.1 µg/mL. The method also demonstrated acceptable precision, accuracy, process efficiency, and stability. Herein, we demonstrate that the aqueous layer generated during the QuEChERS extraction process can serve as a valuable analytical matrix for determining Gly and Glu in blood. This method can be employed by directly adding the derivatization reagent to the aqueous layer without modifying the conventional QuEChERS extraction process. This method has the ability to reduce sample consumption by employing multiple extraction layers with distinct physicochemical characteristics. This is particularly important when only a limited number of sample volumes is available such as in fatal cases or poisoning incidents.
In the past few years, the global uncontrollable spread of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has underscored the need for rapid, sensitive, and accurate detection methods. Given the continuous mutation characteristics of viruses, single-target detection carries the risk of false-positive or false-negative results, whereas dual-target detection can effectively mitigate such risks. Therefore, thermosensitive polymer poly(N-isopropylacrylamide) (PNIPAM) was integrated with an isothermal amplification method-circle-to-circle amplification (C2CA) in this study, enabling individual and simultaneous detection of the SARS-CoV-2 S1 protein and N gene, respectively. PNIPAM-capture probe conjugates enabled specific target recognition and thermal separation from complex matrices, while C2CA achieved exponential signal amplification by leveraging two cascaded rolling circle amplification (RCA) reactions. During single-target detection, the method exhibited linear ranges of 0.1-1000 pg/mL for S1 protein detection and 0.1-1000 pM for Ng detection, with the limit of detection (LOD) of 55 fg/mL and 11.2 fM, respectively. The spiked recovery experiment demonstrated that this method possesses high specificity and robust anti-interference capability. Furthermore, in order to improve the accuracy and efficiency, simultaneous detection was achieved by integrating S1 protein and Ng detection into a single reaction system and labeling differential fluorophores. The LOD was 68.3 fg/mL for S1 protein and 33.1 fM for Ng, respectively. This method combines the advantages of homogeneous reaction and isothermal amplification, eliminating the need for complex instruments and cumbersome procedures, thereby making it suitable for resource-limited settings.
This study reports the synthesis and comprehensive characterization of a new Schiff-base ligand (L), derived from the condensation of 2,5-thiophenedicarboxaldehyde and sulfamerazine. The structural identity of L was unequivocally confirmed through elemental analysis, FT-IR, 1H/13C NMR spectroscopy, and LC-MS/MS measurements. The electrochemical behavior of L was investigated on a glassy carbon electrode in an anhydrous medium, revealing an irreversible, diffusion-controlled redox process best described by an electrochemical-chemical mechanism. The interaction between L and DNA was examined using voltammetric and spectrophotometric techniques. Differential pulse voltammetry demonstrated a pronounced decrease (44.4%) in the guanine oxidation signal upon interaction with L, indicating strong binding with an estimated binding constant of 1.04 × 106 M-1. Complementary UV-Vis studies showed a hypochromic effect accompanied by a hypsochromic shift in the ligand's absorption spectrum, consistent with an intercalative binding mode, yielding a Kb value of 1.44 × 106 M-1. Molecular docking simulations supported the experimental findings by revealing that L preferentially binds within the minor groove of DNA. The interaction is stabilized through a network of noncovalent forces, including conventional hydrogen bonds, van der Waals interactions, C-H···X contacts, and π-sulfur contributions, with a calculated binding energy of - 8.8 kcal mol- 1. Overall, the combined electrochemical, spectroscopic, and theoretical results demonstrate that the synthesized Schiff-base ligand L exhibits high affinity toward DNA, positioning it as a promising candidate for further pharmacological evaluation.
Approximately three decades ago, in response to the growing demand for rapid and sensitive analysis of small-volume samples, monolithic column technology emerged contemporaneously with other key concepts in analytical chemistry, such as the micro-total analysis system (µTAS) and lab-on-a-chip technology. These innovations attracted considerable attention as paradigm-shifting tools in the field. In the post-genomic era in particular, where miniaturization and high-throughput workflows became critical, monoliths-characterized by their continuous porous structure, high permeability, and low back pressure-were recognized as next-generation separation media, especially in omics-driven research. However, subsequent advances in liquid chromatography-most notably the development of core-shell particle packing materials and the widespread adoption of ultra-high-performance liquid chromatography (UHPLC)-gradually diminished the relative advantages of monolithic columns in standard high-throughput HPLC applications. Despite this shift, their intrinsic features, including ease of fabrication, outstanding flow properties, and flexible moldability into diverse formats, have continued to generate new value. In recent years, applications of monoliths have expanded beyond analytical separations into diverse fields, including biopharmaceutical purification (e.g., antibody drugs), solid-phase extraction, immobilized catalytic systems, and integration into micro- and nanoscale devices. This review provides a comprehensive overview of the three-decade evolution of monolithic column technology, highlighting its historical context, current applications, and emerging roles in both analytical and preparative sciences within the broader context of evolving analytical technologies.
The water content of organic solvents was determined by the ligand dissociation of a tris(2-methyl-8-quinolinolato)indium(III) complex. Water in the organic solvent reacts with the indium complex to induce a ligand-exchange reaction. The fluorescence of deprotonated 2-methyl-8-quinolinol disappears when the ligand-exchange reaction forms a neutral molecule; thus, the complex can serve as a turn-off water-detection sensor. We measured the water content of various organic solvents, including ethyl acetate, 1-octanol, and ethanol. The indium complex was dissolved in a water-containing organic solvent, the fluorescence of the 8-quinolonolate ion was measured, and determination curves were constructed based on the decrease in fluorescence intensity. To demonstrate the versatility of the present method, we measured the water content of alcoholic drinks. These results are consistent with the data obtained by Karl Fischer (KF) titration. Although the limits of detection and quantification were not as low as those of the KF titration, the simple experimental setup and procedure of this method are favorable for its application.
This study investigates the electrochemiluminescence (ECL) behavior of water-soluble cadmium telluride quantum dots (CdTe QDs) synthesized via a microwave-assisted hydrothermal method. The ECL response was examined in the presence of tri-n-propylamine (TPrA) as a coreactant, revealing two anodic ECL emissions, denoted as ECL1 and ECL2, at potentials of + 0.85 V and + 1.2 V, corresponding to TPrA oxidation and CdTe QD oxidation, respectively. These emission intensities showed strong dependence on pH, suggesting multiple mechanistic pathways. In situ fluorescence microscopy was employed to observe interactions between electrogenerated TPrA intermediates and CdTe QDs at the electrode surface, providing insights into the reaction mechanisms. It is proposed that ECL1 arises from reactions involving the TPrA•+ intermediate under mildly basic conditions (pH 8-9), where both TPrA•+ and TPrA• radicals facilitate electron transfer with CdTe QDs, resulting in low-potential ECL emission. The findings demonstrate that TPrA•+ acts as both a fluorescence quencher and a reactive intermediate, advancing understanding of the pH-dependent anodic ECL mechanism of semiconductor QDs.
Narrow therapeutic index drugs (NTIDs) require precise monitoring to ensure efficacy and prevent toxicity, yet their analysis in complex biological matrices remains challenging. This study presents a novel sonic-spray ionization mass spectrometry (SSI-MS) method for the rapid and sensitive analysis of NTIDs, using tacrolimus as a model compound. The custom-built SSI source operates without high voltage or heating, relying solely on a coaxial nitrogen flow for gentle and efficient ionization. Under optimized conditions, the method achieved a low limit of quantitation (5 ng/mL) and excellent linearity (R² = 0.999) across the clinically relevant therapeutic window (5-200 ng/mL). Compared to electrospray ionization, SSI provided a cleaner background and a 1.88-fold improvement in the signal-to-noise ratio. The accuracy of this method was validated in mice serum, with recoveries ranging from 99.8% to 106.8% and relative standard deviations below 8.4%. Furthermore, the platform successfully detected tacrolimus directly in a saline matrix. These results demonstrate that SSI-MS is a powerful, high-performance tool for the rapid and reliable quantification of NTIDs, offering significant potential for advancing therapeutic drug monitoring in clinical practice.
In hydroponic cultivation, pH and electrical conductivity are currently widely used as indicators for nutrient management, whereas the concentrations and compositions of individual ions (NO3‒, NO2‒, NH4+, H2PO4‒/HPO42‒, K+) are not precisely monitored. To reduce the environmental load and nutrient costs in future hydroponics, individual fertilization management based on effective and detailed monitoring of nutrients is required, necessitating accurate evaluation of nutrient levels. In this study, we describe the development and application of ion exclusion/cation exchange chromatography (IEC/CEC) with a neutral eluent (40 mM sodium acetate, and 0.5 mM 18-crown-6, pH 7.71) for simultaneous separation of ionic nutrients in a hydroponic fertilizer solution. These problems of the degradation of the separation column due to the precipitation of metal ion species under alkaline elution condition and the oxidation of NO2‒ to NO3‒ encountered under acidic eluent used in previously reported chromatographic studies were avoided while ensuring the base gel stability by using a polymer-based zwitterionic exchanger with neutral eluent. In addition, the developed IEC/CEC method was successfully applied to monitor the temporal evolution of the amount of target ionic nutrients in hydroponic solutions.
Accurate glucose analysis has been a major research focus for the past five decades since the pioneering development of enzymatic glucose sensing, driven by the global demand for rapid and reliable diagnostics. In contrast to well-established enzymatic glucose sensors, the development of chemical sensors based on supramolecular receptors remains a developing area. Among the supramolecular receptors for glucose, phenylboronic acid (PBA) derivatives provide unique functions, such as the formation of boronate esters with glucose and their reversibility. In this study, we focus on organic field-effect transistors (OFETs) combined with PBA derivatives as chemical sensors. Although the beneficial properties of OFETs have been explored for physical sensor applications in organic electronics, the instability of organic devices remains a major limitation for chemical sensing applications. To address this issue, an extended-gate structure was employed as the OFET-based chemical sensor configuration. In this sensor design, an extended-gate electrode functionalized with a PBA derivative self-assembled monolayer was connected to the gate electrode of the OFET, enabling glucose detection via boronate ester formation at the aqueous-sensing electrode interface. In this mini-review, we introduce strategies for establishing non-enzymatic glucose sensors using OFETs with multifunctionalized extended-gate electrodes. Notably, selective glucose detection in human blood plasma has been demonstrated by combining a two-dimensional material that suppresses the physical adsorption of endogenous proteins onto an extended-gate electrode. Finally, an approach that integrates a microfluidic chamber into an extended-gate-based OFET device is introduced to highlight the inherent reversibility of the PBA derivative.
This work presents the advantages of modifying glassy carbon electrodes with a graphene aerogel (GA) dispersed in polyethylenimine (PEI). The presence of GA entrapped in PEI produces a catalytic effect that greatly facilitates the separation of the anodic peaks of ascorbic acid (AA) and uric acid (UA), enabling their detection and quantification by differential pulse voltammetry (DPV). The result is a highly efficient dual electrochemical sensor with a sensitivity of approximately 2.13 × 104 µAM− 1 for AA and 5.0 × 104 µAM− 1 UA. The current response showed a linear relationship for AA when the concentration ranged from 1.0 to 10 × 10− 4 M, with a minimum detection concentration of 0.25 µM and a relative standard deviation (RSD) of 2.0%. For UA, the lineal range was 1.0–15.0 × 10− 5 M, with a minimum detection concentration of 9 µM and an RSD of 2.8%. The promising analytical performance, which allows the evaluation of AA and UA, enables accurate quantification of AA in pharmaceutical samples and UA in urine without the use of enzymes or pretreatment.