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Enzymatic sensor for phenols based on titanium dioxide generating surface confined ROS after treatment with H2O2
摘要： Titanium dioxide (TiO2) is a popular material as host matrix for enzymes. We now evidence that TiO2 can accumulate and retain reactive oxygen species after treatment by hydrogen peroxide (H2O2) and support redox cycling of a phenolic analyte between horseradish peroxidase (HRP) and an electrode. The proposed detection scheme is identical to that of second generation biosensors, but the measuring solution requires no dissolved H2O2. This significantly simplifies the analysis and overcomes issues related to H2O2 being present (or generated) in the solution. The modified electrodes showed rapid stabilization of the baseline, a low noise level, fast realization of a steady-state current response, and, in addition, improved sensitivity and limit of detection compared to the conventional approach, i.e. in the presence of H2O2 in the measuring solution. Hydroquinone, 4-aminophenol, and other phenolic compounds were successfully detected at sub-μM concentrations. Particularly, a linear response in the concentration range between 0.025 and 2 μM and LOD of 24 nM was demonstrated for 4-aminophenol. The proposed sensor design goes beyond the traditional concept with three sensors' generations offering a new possibility for the development of enzymatic sensors based on peroxidases and the formation of ROS on titania after treatment with H2O2.
关键词： Hydroperoxyl species,Titanium dioxide,Horseradish peroxidase,Bioelectrochemistry,Hydrogen peroxide
更新于2025-09-23 15:23:52
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[Lecture Notes in Electrical Engineering] Sensors Volume 539 (Proceedings of the Fourth National Conference on Sensors, February 21-23, 2018, Catania, Italy) || Portable Optoelectronic System for Monitoring Enzymatic Chemiluminescent Reaction
摘要： This work presents a portable lab-on-chip system, based on thin film electronic devices and an all-glass microfluidic network, for the real-time monitoring of enzymatic chemiluminescent reactions. The microfluidic network is patterned, through wet etching, in a 1.1 mm-thick glass substrate that is subsequently bonded to a 0.5 mm-thick glass substrate. The electronic devices are amorphous silicon p-i-n photosensors, deposited on the outer side of the thinner glass substrate. The photosensors, the microfluidic network and the electronic boards reading out the photodiodes' current are enclosed in a small metallic box (10 × 8 × 15 cm3) in order to ensure shielding from electromagnetic interferences. Preliminary tests have been performed immobilizing horseradish peroxidase on the inner wall of the microchannel as model enzyme for detecting hydrogen peroxide. Limits of detection and quantification equal to 18 and 60 μM, respectively, have been found. These values are comparable to the best performances reported in literature for chemiluminescent-based optofluidic sensors.
关键词： Amorphous silicon,Photosensors,Enzymatic reactions,Anodic bonding,Horseradish peroxidase,Microfluidics
更新于2025-09-19 17:15:36
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The Scopoletin-HRP Fluorimetric Determination of H2O2 in Seawaters—A Plea for the Two-Stage Protocol
摘要： A single solution protocol has been widely used for the ?uorimetric determination of H2O2 in natural waters by its bleaching of the ?uorescing scopoletin in the presence of the enzyme horseradish peroxidase (HRP). In this protocol, the reaction between scopoletin and H2O2 in the sample and the subsequent internal additions, and the measurements of the ?uorescence are all carried out at a single pH in a ?uorometer cell. It is found that this protocol is prone to four sources of possible error. The variability in the reaction stoichiometry between scopoletin and H2O2 in the presence of varying amounts of excess scopoletin, the effect of pH on the rate of reaction between scopoletin and H2O2, the photobleaching of scopoletin, and the de-activation of HRP. These possible sources of error can be circumvented in a two-stage protocol in which the reaction between H2O2 and scopoletin is carried out immediately upon sampling at a pH of 7, and the measurement of the ?uorescence is carried out later on at a pH of 9. It should be the protocol of choice. Furthermore, in the two-stage protocol, after the initial reaction between H2O2 and scopoletin, the sample may be stored at room temperature for six days and at 4 ?C for at least a month before its ?uorescence is measured. This option can signi?cantly reduce the logistics in the ?eld.
关键词： hydrogen peroxide,?uorimetric determination,horseradish peroxidase,scopoletin
更新于2025-09-09 09:28:46