A glucose oxidase-coupled DNAzyme sensor for glucose detection in tears and saliva

• Published in: Biosensors & bioelectronics 2015-08, Vol.70, p.455-461
• Main Authors: Liu, Chengcheng, Sheng, Yongjie, Sun, Yanhong, Feng, Junkui, Wang, Shijin, Zhang, Jin, Xu, Jiacui, Jiang, Dazhi
• Format: Article
• Language: English
• Subjects: Biosensing Techniques - instrumentation; Biosensors; Cleavage; DNA, Catalytic - chemistry; Equipment Design; Equipment Failure Analysis; Glucose; Glucose - analysis; Glucose - chemistry; Glucose oxidase; Glucose Oxidase - chemistry; Hydrogen Peroxide - analysis; Hydrogen Peroxide - chemistry; Monitoring; Non-invasive technology; Patients; Pistol-like DNAzyme; Reproducibility of Results; Saliva; Saliva - chemistry; Sensitivity and Specificity; Slopes; Tear; Tearing; Tears - chemistry
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2015.03.070

Biosensors have been widely investigated and utilized in a variety of fields ranging from environmental monitoring to clinical diagnostics. Glucose biosensors have triggered great interest and have been widely exploited since glucose determination is essential for diabetes diagnosis. In here, we designed a novel dual-enzyme biosensor composed of glucose oxidase (GOx) and pistol-like DNAzyme (PLDz) to detect glucose levels in tears and saliva. First, GOx, as a molecular recognition element, catalyzes the oxidation of glucose forming H2O2; then PLDz recognizes the produced H2O2 as a secondary signal and performs a self-cleavage reaction promoted by Mn2+, Co2+ and Cu2+. Thus, detection of glucose could be realized by monitoring the cleavage rate of PLDz. The slope of the cleavage rate of PLDz versus glucose concentration curve was fitted with a Double Boltzmann equation, with a range of glucose from 100nM to 10mM and a detection limit of 5μM. We further applied the GOx–PLDz 1.0 biosensor for glucose detection in tears and saliva, glucose levels in which are 720±81μM and 405±56μM respectively. Therefore, the GOx–PLDz 1.0 biosensor is able to determine glucose levels in tears and saliva as a noninvasive glucose biosensor, which is important for diabetic patients with frequent/continuous glucose monitoring requirements. In addition, induction of DNAzyme provides a new approach in the development of glucose biosensors. •Pistol-like DNAzyme (PLDz) as new ‘material’ is applied to construct a glucose biosensor.•PLDz and GOx are integrated in the cascade by H2O2 to develop a novel dual-enzyme glucose biosensor.•PLDz in the biosensor plays a dual role in both secondary signal recognition and signal output.•GOx–PLDz 1.0 is able to determine glucose levels in saliva and tears as a noninvasive biosensor.