Figure 1. The schematic illustration and assembly of 3D optical TIRI chip 3.2. Detection Method and Data Analysis Method The principle of detection of the 3D TIRI optical chip is a one-step sandwich method shown in figure 2. When the samples were added, the sample rehydrated the trace mAb and magnetic particle in the detection area and then the antigen action with the composites. The bidirectional magnetic force was open and the capture antibody in the bottom acted with the Mag-mAb-Ag complex and form magnetic spots at the bottom of the reaction area. The total internal optical signals are subject to magnetic speckle interference, and the signal was inverse correlation with the antigen Matlab software was used to assay the obtained magnetic spot imaging. Figure 2. Schematic diagram of detection principle of sandwich immunoassay method 3. Results 3.1. Optimization on the reflection angle of the 3D Chip One major aim of the assay development was the capture of the clear images that during one-step sandwich immunoassay. The incidence angle and reflection angle of the 3D optical chip was symmetric in the center of the reaction zone. The incidence angle should meet the conditions of total internal reflection imaging according to the index of the material of the 3D chip. The angular range of the reflection angle has important influence on imaging quality. When the reflection angle continues to increase, the image sharpness decreased rapidly with the increasing angle of reflection. The image changed from circles to ellipse when the angle gradually increased and the image aggravated when the angle reached 70 degree angle (Fig. 3). It was too small to form a total internal reflection if the reflection angle is less than 45 degree. Figure 3. The TIRI image of 3D chip at different reflection angle 3.2. Detection of hs-CRP The standard curves with a dilution series of standard CRP samples by PBS buffer were created. The assay achieved an LOD value of 0.1 ng/mL in standard CRP samples. The linear fits to the curves are shown in Fig. 4. The sensitivity of the assay is sufficient to distinguish hs-CRP levels during 0.1~10 ng/mL (Fig.4). To enable the measurement of lower and higher concentrations of CRP, further detection and improvements to the chip system are necessary. The assay required no sample preparation and is therefore easy to handle, which is suitable for POC measurement at the patient.
Figure 1. The schematic illustration and assembly of 3D optical TIRI chip 3.2. Detection Method and Data Analysis Method The principle of detection of the 3D TIRI optical chip is a one-step sandwich method shown in figure 2. When the samples were added, the sample rehydrated the trace mAb and magnetic particle in the detection area and then the antigen action with the composites. The bidirectional magnetic force was open and the capture antibody in the bottom acted with the Mag-mAb-Ag complex and form magnetic spots at the bottom of the reaction area. The total internal optical signals are subject to magnetic speckle interference, and the signal was inverse correlation with the antigen Matlab software was used to assay the obtained magnetic spot imaging. Figure 2. Schematic diagram of detection principle of sandwich immunoassay method 3. Results 3.1. Optimization on the reflection angle of the 3D Chip One major aim of the assay development was the capture of the clear images that during one-step sandwich immunoassay. The incidence angle and reflection angle of the 3D optical chip was symmetric in the center of the reaction zone. The incidence angle should meet the conditions of total internal reflection imaging according to the index of the material of the 3D chip. The angular range of the reflection angle has important influence on imaging quality. When the reflection angle continues to increase, the image sharpness decreased rapidly with the increasing angle of reflection. The image changed from circles to ellipse when the angle gradually increased and the image aggravated when the angle reached 70 degree angle (Fig. 3). It was too small to form a total internal reflection if the reflection angle is less than 45 degree. Figure 3. The TIRI image of 3D chip at different reflection angle 3.2. Detection of hs-CRP The standard curves with a dilution series of standard CRP samples by PBS buffer were created. The assay achieved an LOD value of 0.1 ng/mL in standard CRP samples. The linear fits to the curves are shown in Fig. 4. The sensitivity of the assay is sufficient to distinguish hs-CRP levels during 0.1~10 ng/mL (Fig.4). To enable the measurement of lower and higher concentrations of CRP, further detection and improvements to the chip system are necessary. The assay required no sample preparation and is therefore easy to handle, which is suitable for POC measurement at the patient.