Electroanalysis最新文献

Diabetes mellitus is a common metabolic disease that requires frequent and accurate glucose monitoring to prevent serious complications and improve outcomes of treatment. Traditional glucose-monitoring methods like finger pricking and injectable insulin delivery are invasive, painful, and often inconvenient for long-term use which can adversely affect patient compliance. In addition, the poor permeability of the stratum corneum limits the effectiveness of many conventional transdermal systems, highlighting the need for minimally invasive and patient-friendly alternatives. Microneedle-based biosensors have attracted considerable interest as promising platforms for continuous glucose monitoring, since they can penetrate the outer layer of skin with minor pain and directly access the interstitial fluid to detect glucose in real time. Microneedle design, materials, fabrication technologies, and sensing strategies have been substantially advanced. However, most of the existing reviews discuss these aspects individually and have limited coverage on the synergistic effects of the microneedle structure, material property, fabrication strategy, and sensing mechanism on the biosensor performance and clinical applicability. This review focuses on the recent advances of microneedle-based glucose biosensors including different microneedle architectures, fabrication techniques, material systems, and sensing mechanisms such as enzymatic, nonenzymatic, colorimetric, fluorescence-based, and surface-enhanced Raman scattering (SERS)–based systems. The effects of microneedle design mechanical properties on sensing efficiency, biocompatibility, and patient comfort are discussed in detail. Current challenges such as biofouling, long-term stability, manufacturing complexity, and wearable integration are also discussed. Overall, microneedle-based biosensors are promising for minimally invasive and personalized management of diabetes.

Diabetes mellitus is a common metabolic disease that requires frequent and accurate glucose monitoring to prevent serious complications and improve outcomes of treatment. Traditional glucose-monitoring methods like finger pricking and injectable insulin delivery are invasive, painful, and often inconvenient for long-term use which can adversely affect patient compliance. In addition, the poor permeability of the stratum corneum limits the effectiveness of many conventional transdermal systems, highlighting the need for minimally invasive and patient-friendly alternatives. Microneedle-based biosensors have attracted considerable interest as promising platforms for continuous glucose monitoring, since they can penetrate the outer layer of skin with minor pain and directly access the interstitial fluid to detect glucose in real time. Microneedle design, materials, fabrication technologies, and sensing strategies have been substantially advanced. However, most of the existing reviews discuss these aspects individually and have limited coverage on the synergistic effects of the microneedle structure, material property, fabrication strategy, and sensing mechanism on the biosensor performance and clinical applicability. This review focuses on the recent advances of microneedle-based glucose biosensors including different microneedle architectures, fabrication techniques, material systems, and sensing mechanisms such as enzymatic, nonenzymatic, colorimetric, fluorescence-based, and surface-enhanced Raman scattering (SERS)–based systems. The effects of microneedle design mechanical properties on sensing efficiency, biocompatibility, and patient comfort are discussed in detail. Current challenges such as biofouling, long-term stability, manufacturing complexity, and wearable integration are also discussed. Overall, microneedle-based biosensors are promising for minimally invasive and personalized management of diabetes.

A portable multifrequency electrochemical response analyzer was developed on an ESP32 microcontroller platform for comparative impedance-sensitive characterization of aqueous electrolytes. The instrument employs PWM square-wave excitation (1–15 kHz), a two-electrode stainless steel probe, and RC signal conditioning with 12-bit analog-to-digital converter (ADC) sampling. Response values are determined via a voltage-divider relationship between electrolyte impedance and the conditioning network, yielding comparative measurements in arbitrary units. Analysis of strong electrolytes (HCl, NaOH, KOH, NaCl) and weak electrolyte (CH₃COOH) at 0.001–1 M revealed monotonically increasing responses with excitation frequency (gain ratio 14.8–23.6). Strong electrolytes exhibited moderate frequency dependence consistent with complete ionization, whereas acetic acid showed markedly higher absolute responses and enhanced interfacial polarization due to partial ionization, enabling quantitative class-level discrimination. Repeatability at 0.1 M NaCl (n = 5) yielded CV < 2.1% across all frequencies. The analyzer offers a small, cost-effective screening platform for portable electrochemical characterization in resource-constrained environments, made WiFi enabled with real-time visualization and CSV data export, enabling use in environmental assessment, process monitoring, and analytical screening.

A portable multifrequency electrochemical response analyzer was developed on an ESP32 microcontroller platform for comparative impedance-sensitive characterization of aqueous electrolytes. The instrument employs PWM square-wave excitation (1–15 kHz), a two-electrode stainless steel probe, and RC signal conditioning with 12-bit analog-to-digital converter (ADC) sampling. Response values are determined via a voltage-divider relationship between electrolyte impedance and the conditioning network, yielding comparative measurements in arbitrary units. Analysis of strong electrolytes (HCl, NaOH, KOH, NaCl) and weak electrolyte (CH₃COOH) at 0.001–1 M revealed monotonically increasing responses with excitation frequency (gain ratio 14.8–23.6). Strong electrolytes exhibited moderate frequency dependence consistent with complete ionization, whereas acetic acid showed markedly higher absolute responses and enhanced interfacial polarization due to partial ionization, enabling quantitative class-level discrimination. Repeatability at 0.1 M NaCl (n = 5) yielded CV < 2.1% across all frequencies. The analyzer offers a small, cost-effective screening platform for portable electrochemical characterization in resource-constrained environments, made WiFi enabled with real-time visualization and CSV data export, enabling use in environmental assessment, process monitoring, and analytical screening.

Dopamine is a key catecholaminergic neurotransmitter, and its precise determination in biological fluids is essential for studying neurological dysfunction and developing diagnostic approaches. This study reports a thermally optimized carbon quantum dot-embedded zeolitic imidazolate framework-8 (CDs@ZIF-8) nanocomposite as an electrochemical sensing platform for ultrasensitive dopamine detection. Carbon quantum dots were synthesized via a hydrothermal route using L-proline and o-phenylenediamine as carbon and nitrogen precursors and subsequently integrated into the ZIF-8 framework through pH-regulated electrostatic impregnation. Structural characterization confirmed the successful incorporation of CDs while preserving the sodalite-type crystalline structure of ZIF-8. The introduction of CDs significantly improved the electrochemical properties of ZIF-8 by reducing the charge transfer resistance from approximately 510 to 55 Ω and enhancing dopamine oxidation performance through improved electron transport and increased accessible active sites. Temperature optimization identified 30 °C as the optimal sensing condition, enabling the CDs@ZIF-8-modified glassy carbon electrode to achieve a wide linear detection range from 0.05 to 180 μM, a sensitivity of 0.2156 μA μM⁻¹, and a detection limit of 18 nM (S/N = 3). The sensor exhibited high selectivity against common interfering substances, excellent storage stability with 93.8% signal retention after 10 days, and reliable analytical performance in fetal bovine serum samples with recoveries of 97.1%–104.8%. The developed CDs@ZIF-8 platform provides an effective strategy for improving metal–organic framework-based electrochemical sensing systems and demonstrates potential for dopamine monitoring in complex biological matrices.

Dopamine is a key catecholaminergic neurotransmitter, and its precise determination in biological fluids is essential for studying neurological dysfunction and developing diagnostic approaches. This study reports a thermally optimized carbon quantum dot-embedded zeolitic imidazolate framework-8 (CDs@ZIF-8) nanocomposite as an electrochemical sensing platform for ultrasensitive dopamine detection. Carbon quantum dots were synthesized via a hydrothermal route using L-proline and o-phenylenediamine as carbon and nitrogen precursors and subsequently integrated into the ZIF-8 framework through pH-regulated electrostatic impregnation. Structural characterization confirmed the successful incorporation of CDs while preserving the sodalite-type crystalline structure of ZIF-8. The introduction of CDs significantly improved the electrochemical properties of ZIF-8 by reducing the charge transfer resistance from approximately 510 to 55 Ω and enhancing dopamine oxidation performance through improved electron transport and increased accessible active sites. Temperature optimization identified 30 °C as the optimal sensing condition, enabling the CDs@ZIF-8-modified glassy carbon electrode to achieve a wide linear detection range from 0.05 to 180 μM, a sensitivity of 0.2156 μA μM⁻¹, and a detection limit of 18 nM (S/N = 3). The sensor exhibited high selectivity against common interfering substances, excellent storage stability with 93.8% signal retention after 10 days, and reliable analytical performance in fetal bovine serum samples with recoveries of 97.1%–104.8%. The developed CDs@ZIF-8 platform provides an effective strategy for improving metal–organic framework-based electrochemical sensing systems and demonstrates potential for dopamine monitoring in complex biological matrices.

The electrochemical oxidation of 2,5-dihydroxybenzoic acid (2,5-DHBA) in the presence of p-toluenesulfinic acid (TSA) was investigated by cyclic voltammetry and controlled-potential coulometry. The results revealed an ECEC mechanism, leading to the formation of a new disulfone derivative. In contrast, investigation of five other hydroquinone derivatives under identical conditions revealed that their electrochemical oxidation in the presence of the nucleophile follows an EC mechanism. To clarify the origin of this mechanistic difference, density functional theory (DFT) calculations were performed using various functionals in combination with CPCM and SMD solvation models. Comparison of calculated oxidation free energies (ΔG_tot) with experimental voltammetric data identified the M06-2X-D3/6-311++G(d,p)/SMD level as the most reliable method, providing excellent agreement with experiment. The results demonstrated that the total change in Gibbs free energy of the electrochemical oxidation of the species is the key factor governing the reaction pathway. Products whose ΔG_tot are higher than those of the corresponding starting materials do not undergo further oxidation under the experimental conditions, resulting in an EC mechanism. In contrast, species with lower ΔG_tot values are susceptible to further oxidation, leading to an ECEC mechanism.

The electrochemical oxidation of 2,5-dihydroxybenzoic acid (2,5-DHBA) in the presence of p-toluenesulfinic acid (TSA) was investigated by cyclic voltammetry and controlled-potential coulometry. The results revealed an ECEC mechanism, leading to the formation of a new disulfone derivative. In contrast, investigation of five other hydroquinone derivatives under identical conditions revealed that their electrochemical oxidation in the presence of the nucleophile follows an EC mechanism. To clarify the origin of this mechanistic difference, density functional theory (DFT) calculations were performed using various functionals in combination with CPCM and SMD solvation models. Comparison of calculated oxidation free energies (ΔG_tot) with experimental voltammetric data identified the M06-2X-D3/6-311++G(d,p)/SMD level as the most reliable method, providing excellent agreement with experiment. The results demonstrated that the total change in Gibbs free energy of the electrochemical oxidation of the species is the key factor governing the reaction pathway. Products whose ΔG_tot are higher than those of the corresponding starting materials do not undergo further oxidation under the experimental conditions, resulting in an EC mechanism. In contrast, species with lower ΔG_tot values are susceptible to further oxidation, leading to an ECEC mechanism.

Large-scaleapplicationof lithium-ion batteries has been hampered by thermal safety issues associated with organic electrolytes based on carbonates. The development of flame-resistant or noncombustible electrolytes is therefore essential. Recently, researchers have shown increasing interest in novel ionic liquid-based electrolytes. However, pure ionic liquids are unsuitable as electrolyte solvents. 1-Butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([Bmim]TF₂N) is a favorable candidate for binary electrolytes owing to its higher conductivity and lower viscosity. Herein, a series of experiments was conducted on binary electrolytes composed of [Bmim]TF₂N and carbonate-based electrolytes (1 M LiPF₆ in EC/DMC/EMC, 1:1:1 v/v/v). The results revealed that the [Bmim]TF₂N binary electrolyte outperformed the carbonate electrolyte.The [Bmim]TF₂N-containing electrolytes exhibited higher total ionic conductivity than the carbonate-based electrolyte under the tested conditions. The binary electrolytes exhibited 6.61% and 11.63% greater flame-retardant efficiencies than the carbonate electrolytes when the [Bmim]TF₂N concentrations were 20% ([Bmim]TF₂N-20%) and 40% ([Bmim]TF₂N-40%), respectively. After 100 cycles, LiFePO₄ batteries employing [Bmim]TF₂N-20% and [Bmim]TF₂N-40% delivered capacities of 141.8 and 141.4 mAh g⁻¹, respectively, with corresponding capacity retention rates that were 3.52% and 4.4% higher than those of the carbonate batteries (132.5 mAh g⁻¹). Furthermore, among all the electrolytes tested, the [Bmim]TF₂N-20% binary electrolyte exhibited the highest charge/discharge capacity under high-rate cycling conditions.

Large-scaleapplicationof lithium-ion batteries has been hampered by thermal safety issues associated with organic electrolytes based on carbonates. The development of flame-resistant or noncombustible electrolytes is therefore essential. Recently, researchers have shown increasing interest in novel ionic liquid-based electrolytes. However, pure ionic liquids are unsuitable as electrolyte solvents. 1-Butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([Bmim]TF₂N) is a favorable candidate for binary electrolytes owing to its higher conductivity and lower viscosity. Herein, a series of experiments was conducted on binary electrolytes composed of [Bmim]TF₂N and carbonate-based electrolytes (1 M LiPF₆ in EC/DMC/EMC, 1:1:1 v/v/v). The results revealed that the [Bmim]TF₂N binary electrolyte outperformed the carbonate electrolyte.The [Bmim]TF₂N-containing electrolytes exhibited higher total ionic conductivity than the carbonate-based electrolyte under the tested conditions. The binary electrolytes exhibited 6.61% and 11.63% greater flame-retardant efficiencies than the carbonate electrolytes when the [Bmim]TF₂N concentrations were 20% ([Bmim]TF₂N-20%) and 40% ([Bmim]TF₂N-40%), respectively. After 100 cycles, LiFePO₄ batteries employing [Bmim]TF₂N-20% and [Bmim]TF₂N-40% delivered capacities of 141.8 and 141.4 mAh g⁻¹, respectively, with corresponding capacity retention rates that were 3.52% and 4.4% higher than those of the carbonate batteries (132.5 mAh g⁻¹). Furthermore, among all the electrolytes tested, the [Bmim]TF₂N-20% binary electrolyte exhibited the highest charge/discharge capacity under high-rate cycling conditions.