A disposable paper-based glucose biosensor with direct electron transfer (DET) of glucose oxidase (GOX) was developed through simple covalent immobilization of GOX on a carbon electrode surface using ...zero-length cross-linkers. This glucose biosensor exhibited a high electron transfer rate (ks, 3.363 s
) as well as good affinity (km, 0.03 mM) for GOX while keeping innate enzymatic activities. Furthermore, the DET-based glucose detection was accomplished by employing both square wave voltammetry and chronoamperometric techniques, and it achieved a glucose detection range from 5.4 mg/dL to 900 mg/dL, which is wider than most commercially available glucometers. This low-cost DET glucose biosensor showed remarkable selectivity, and the use of the negative operating potential avoided interference from other common electroactive compounds. It has great potential to monitor different stages of diabetes from hypoglycemic to hyperglycemic states, especially for self-monitoring of blood glucose.
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•We for the first time develop a low-cost electrochemical immunosensor on paper for quantitative analysis of pancreatic cancer biomarker PEAK1.•The combination of electrochemical ...detection with gold nanoparticles enables high detection sensitivity.•Graphene oxide is drop-coated on carbon electrodes, providing a simple strategy to link antibodies to electrodes.•The immunosensor exhibits a low limit of detection of 10 pg mL−1 PEAK1, indicating high detection sensitivity for early cancer diagnosis.•This electrochemical platform has tremendous potential for point-of-care early diagnosis of a variety of cancers in resource-poor settings.
Due to the lack of specific early detection methods for pancreatic cancer, it usually goes undetected until it is advanced. By employing paper-based electrodes (PPEs), herein we for the first time developed a disposable low-cost paper-based immunosensor for rapid early quantitative detection of pancreatic cancer with a new biomarker, pseudopodium-enriched atypical kinase one, SGK269 (PEAK1). The immunosensor was constructed by fabricating PPEs immobilized with the versatile nanomaterial graphene oxide for the incorporation of antibodies to form an immunosensing platform, without the need of complicated surface modification. After it was confirmed that the PPEs exhibited excellent electrochemical properties, a sandwich-type electrochemical immunosensor was subsequently constructed by employing graphene oxide layers immobilized with anti-PEAK1, and the antibody conjugated with gold nanoparticles (AuNPs-tagged-Anti PEAK1). Further, spectral and surface characteristic studies confirmed the formation of the immunosensing platform. The immunosensor for PEAK1 exhibited a wide linear range between 10 pg mL−1 and 106 pg mL−1 with a low limit of detection (LOD) of 10 pg mL−1. The obtained results point towards rapid, sensitive, and specific early diagnosis of pancreatic cancer at the point of care and other low-resource settings.
Importance: Diabetes is a common world-wide disease characterized by insulin resistance and as result there is an increased risk of cardiovascular disease and other metabolic abnormalities, that ...contribute to irreversible end-organ damage. The cause of diabetes is multifactorial and includes genetic, inflammatory and environmental factors plus lifestyle issues. Because in diabetes there are high levels of glucose and glycated hemoglobin, these molecules are used in clinical settings for the acute and chronic management of diabetic patients.Objectives: a. To design and build an electrochemical biological sensor using the enzyme Glucose Oxidase (GOX) to detect glucose in biological fluids.b. To design and build an electrochemical biological sensor using amino-phenyl-boronic acid (APBA) to detect glycated hemoglobin (HbA1c) in blood.Methodology: The two types of electrodes were built using a similar carbon-coated cellulose matrix followed by a surface pretreatment (Pre-Anodization), and by the addition of cross-linking molecules in order to generate specific covalent bonds. Theses cross-linkers attach to anodized cellulose fibers by specific functional groups as carboxyl’s, generating avid binding sites for either GOX or APBA. The GOX transfers electrons to the matrix through its flavin adenine nucleotide (FAD) subunits as its oxidase’s glucose; the number of electrons transferred is proportional to the glucose concentration in the test solution. Due to the presence of catalase activity in the APBA-HbA1c complexes, and in the presence of H2O2, a proportional number of electrons to the number of bound glycated hemoglobin is transferred to the matrix.Results: The specific covalent immobilization of GOX and cofactor APBA, was successfully achieved on carbon precoated cellulose matrix. The proposed use of zero-length cross-linkers create the indispensable molecular bindings sites for the functionality of theses disposable paper-carbon electrodes. The GOX-based sensor showed a high sensitivity (60.8723 μA. mM−1cm−2) and specificity for the detection of glucose. This APBA-based sensor also showed in laboratory settings high specificity and sensitivity (208.9461 μA mM−1cm−2).Conclusions and Relevance: These new laboratories tested electrodes to detect glucose and HbA1c met FDA requirements and have a great potential to be used as new biosensors for the management of diabetes in clinical settings. Furthermore, these electrodes have the potential for clinical acceptance due to their manufacturing friendliness of portability, high sensitivity, high specificity and low costs.
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