Carbon Nanotube Biosensor for Diabetes Disease

Introduction Diabetes mellitus is one of the major causes of death, poor life quality, and disability worldwide. It is caused by hyperglycemia (high blood glucose levels) and insulin shortage (1). Type 1 diabetes or juvenile diabetes, as an insulin-dependent diabetes, is an autoimmune disorder which results from a deficiency in insulin-producing beta cells of the islets of Langerhans and leads to hyperglycemia. Type 2 diabetes or adult-onset diabetes, as a noninsulin-dependent diabetes, is a metabolic disorder involving insulin resistance, also characterized by hyperglycemia. Gestational diabetes mellitus (GDM) resulting from high blood sugar level during pregnancy increases the risk of developing type 2 diabetes for women and their babies within 10 years after delivery, as well (2). Therefore, continuous and accurate glucose sensing in blood and serum is important for diagnosis, self-monitoring, and management of the disease (1). Hence, the innovation of reliable, sensitive, and low-cost biosensors for miniaturization of detection system and development of efficient sensor has significant impact on diagnosis of diabetes biomarker (3,4). Recent advent in nanomaterial sensors offers an opportunity to create portable devices with required sensitivity for non-invasive diabetes diagnosis via saliva, urine or tear. Among various types of nanomaterials, carbon nanotubes (CNTs) have been considered as the most promising materials for the development of future devices to assist in the early sensing of hyperglycemia as the most important biomarker for both types of diabetes (5). Biosensors as selective detectors in transduction integrate the recognizable responses of immobilized biorecognition elements such as enzymes, antibodies, and antigens with their biological sensors and produce an electronically measurable signal for bioassays (6,7). According to various types of bioreceptors, biosensors can be classified as immunobiosensors, genobiosensors and enzymatic biosensors, or optical, piezoelectric, electrochemical, and thermometric biosensors according to signal transduction procedure (8). Functionalized nanoparticles with biomedical applications such as drug administration and tissue engineering have shown considerable potency to be applied in the generation of highly sensitive biosensors recently (6,9,10). The detection limits of various biomarkers like DNA, RNA and glucose have been developed by substantial improvement in nanotechnology and biosensing technology using organic materials such as CNTs and inorganic materials like gold nanostructures (11). Remarkable structural, electronic, and mechanical properties, variable conductivity, and small size, in addition to expanded active surface area make CNT a predominant choice to be applied as a host substance for nanoparticles (12,13). Tremendous sensitivity of CNTs to any miniature change such as biomolecules exposing around their immediate adjacent Abstract Objective: Diabetes is the major and leading cause of death, poor quality of life and organ failure which emphasizes the importance of accurate measuring of body glucose. Carbon nanotube (CNT) biosensors exhibit great sensitivity and selectivity for glucose in blood and body fluids. The most recent progresses on the development of various methods of CNT biosensors for glucose detection are summarized in this review. Methods: For this review, online search of different sources such as PubMed, ISI and Scopus resulted in finding 34 articles correlated with CNT detector and its application in diabetes sensing. Results: The results showed advanced methods of CNT sensor functionalization with various modifiers like polyaniline and techniques such as self-assembly layer-by-layer process. These point-of-care solution-phase nanotube biosensors have significant potency to monitor blood glucose non-invasively and eliminate painful finger prick procedure. Conclusion: In this study, it was concluded that appropriate surface modification of CNT biosensors could play an important role in real-time diagnosis of diabetes. Keyword: Carbon nanotube, Biosensor, Diabetes mellitus detector, Nanotechnology Saeideh Same1*†, Golshan Samee2† Open Access Review Article