A colorimetric biosensor based on a biodegradable fluidic device capable of efficient saliva sampling and salivary biomarker detection

Abstract

The use of saliva as a diagnostic biofluid offers many advantages over traditional blood-based diagnostics, and has the potential to revolutionize the field of point-of-care and personalized medicine. However, there remains a strong demand for precise and convenient saliva sampling and an all-in-one system that can achieve saliva sample loading and biomarker detection in a patient-friendly, easy-to-use, and cost-effective manner. In this study, we developed a biodegradable fluidic device for use in point-of-care diagnostics using saliva as a sample biofluid. The device comprised a sample loading zone and a detection zone connected through channels. A chitosan sponge was used to sample artificial saliva owing to its large absorption capacity and ability to release absorbed saliva, and polyethylene glycol-based hydrogel entrapping enzymes and dyes were used as the sensing module for the colorimetric detection of target biomarkers. When a saliva-absorbed chitosan sponge was inserted into the loading zone and squeezed, the absorbed saliva was released from the sponge and moved to the detection zone containing the hydrogel-based sensing module, where it initiated an enzyme-catalyzed reaction and subsequently induced a color change in the hydrogel. The enzyme-based detection of glucose and creatinine in a clinically useful concentration range confirmed the effectiveness of the proposed fluidic system. The proposed system enabled the quantitative detection of glucose and creatinine both spectrophotometrically and via smartphone-based analysis, highlighting its potential in point-of-care diagnostics.