Hydrogel-integrated multimodal biosensor for the detection of glucose and carcinoembryonic antigen

Multimodal biosensors can reduce false negative/positive rates to produce more reliable results. In this study, we report a multimodal biosensor that can achieve the detection of biomarkers by color, temperature and distance signals. The detection of glucose and carcinoembryonic antigen (CEA) is demonstrated as an example. The horseradish peroxidase (HRP), glucose oxidase (GOx) and 3,3 ',5,5 '-tetramethylbenzidine (TMB) are all entrapped in the gelatin hydrogel. When glucose is present, the final product oxTMB shows the blue signal and photothermal effect that can cause the gel-sol phase transition of the gelatin hydrogel, which enables the detection of glucose based on color, temperature and water flow distance on the pH indicator paper. To further broaden the application of this biosensor, a multimodal immunosensor is constructed to detect CEA using detection antibodymodified MnO2 Nanoflowers (NFs) as detection probe. Based on the oxidase-like activity of MnO2 NFs and the gel-sol transition property of the gelatin hydrogel, the detection of CEA with multiple signals as mentioned above was achieved by the sandwich immunoassay. Additionally, the detection of glucose and CEA is also fulfilled for in real samples. Overall, the hydrogel-integrated multimodal biosensor is simple to operate and the resulting multiple signals can complement each other, providing a versatile method for analysis of biomarkers.