A new methodology for optical biosensing with drop-casting fabrication of sensor chips and irradiation/detection of a single laser beam

Abstract

We propose a new methodology for optical biosensing with drop-casting fabrication of sensor chips and irradiation/detection of a single laser beam. Glucose sensor chips were fabricated by simply depositing a solution, including o-phenylenediamine (oPD), glucose oxidase (GOD), and horseradish peroxidase (HRP), on a glass substrate. A sample solution was dropped on the sensor chip and the concentration was detected by measuring the reflection intensity of the laser beam focused on the chip. A surface deformation induced by the laser irradiation on the chip was observed by electron microscopy, demonstrating that this sensor chip converts the enzyme reactions into morphological changes using the assistance of the laser beam. The mechanism of the laser-induced surface deformation was investigated by testing the effect of sodium azide and fluorescence spectroscopy.

Direct Blue Light-Induced Autocatalytic Oxidation of o-Phenylenediamine for Highly Sensitive Visual Detection of Triaminotrinitrobenzene

“…In contrast, as for the OPD oxidation reaction, the UV–vis absorption spectra do not change when methanol that is an effective scavenger for superoxide radical is added to the reaction system (Figure S7). These results indicate that 1 O 2 is main ROS and cause the photo-oxidation of OPD, which is in good agreement with the experimental results from the green laser-caused oxidaiton of OPD. , Howbeit, the oxOPD has a weak absorption at the laser wavelength (532 nm), as depicted in Figure a,b. At the same time, the laser has a strong energy and significant thermal effect.…”

“…38 These results indicate that 1 O 2 is main ROS and cause the photo-oxidation of OPD, which is in good agreement with the experimental results from the green laser-caused oxidaiton of OPD. 39,40 Howbeit, the oxOPD has a weak absorption at the laser wavelength (532 nm), as depicted in Figure 2a,b. At the same time, the laser has a strong energy and significant thermal effect.…”

An optical pickup enzyme-linked immunosorbent assay (ELISA) with a microfluidic disk

“…In our previous study of glucose detection, a laser beam was focused onto a glass substrate to measure the reection intensity. 14,15 To construct microELISA chips using PMMA, the optical pickup signal obtained with a PMMA substrate was evaluated by experiments and computational simulation (see Fig. S1 in ESI †).…”

“…As an innovative way to solve the problems inherent in colorimetric-based ELISAs, we propose the application of optical pickup detection of horseradish peroxidase (HRP), which was recently developed by our group. 14,15 In principle, this is a method to induce and detect oxidative polymerization (dimerization) of o-phenylenediamine (oPD) using a single laser beam. oPD is a well-known colorimetric reagent used in conventional ELISAs; oxidative polymerization (mainly dimerization) of oPD is catalysed by horseradish peroxidase (HRP), and the reaction product (diaminophenazine: DAP) has an intense colour.…”

“…The detection mechanism was explained in detail in previous reports. 14,15 The oPD reaction occurs with a laser focus of approximately 1 mm in diameter. As a result, the sample volume necessary in this method is on the scale of several nL-pL, which is much smaller as compared with that of conventional ELISA.…”