A Paper-Based Analytical Device Integrated with Smartphone: Fluorescent and Colorimetric Dual-Mode Detection of β-Glucosidase Activity

• Published in: Biosensors (Basel) Vol. 12; no. 10; p. 893
• Main Authors: Zhang, Wei-Yi, Tian, Tao, Peng, Li-Jing, Zhou, Hang-Yu, Zhang, Hao, Chen, Hua, Yang, Feng-Qing
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.10.2022; MDPI
• Subjects: Cellulose; Chemical properties; colorimetric; Colorimetric analysis; Colorimetry; Cost analysis; dual-mode smartphone sensor; Enzymes; Fluorescence; Glucose; Glucosidase; Glucosides; Green products; Irradiation; Light irradiation; Measurement; Methods; Optical properties; paper-based analytical device; Reagents; Screen printing; Sensors; Smart phones; Smartphones; Spectrophotometer; Substrates; Ultraviolet radiation; β-Glucosidase; β-glucosidase activity; China; Beijing China
• ISSN: 2079-6374; 2079-6374
• DOI: 10.3390/bios12100893

In this work, indoxyl-glucoside was used as the substrate to develop a cost-effective, paper-based analytical device for the fluorescent and colorimetric dual-mode detection of β-glucosidase activity through a smartphone. The β-glucosidase can hydrolyze the colorless substrate indoxyl-glucoside to release indoxyl, which will be self-oxidized to generate green products in the presence of oxygen. Meanwhile, the green products emit bright blue-green fluorescence under ultraviolet–visible light irradiation at 365 nm. Fluorescent or colorimetric images were obtained by a smartphone, and the red-green-blue channels were analyzed by the Adobe Photoshop to quantify the β-glucosidase activity. Under the optimum conditions, the relative fluorescent and colorimetric signals have a good linear relationship with the activity of β-glucosidase, in the range of 0.01–1.00 U/mL and 0.25–5.00 U/mL, and the limits of detection are 0.005 U/mL and 0.0668 U/mL, respectively. The activities of β-glucosidase in a crude almond sample measured by the fluorescent and colorimetric methods were 23.62 ± 0.53 U/mL and 23.86 ± 0.25 U/mL, respectively. In addition, the spiked recoveries of normal human serum and crude almond samples were between 87.5% and 118.0%. In short, the paper-based device, combined with a smartphone, can provide a simple, environmentally friendly, and low-cost method for the fluorescent and colorimetric dual-mode detection of β-glucosidase activity.