Electrochemical detection of glycan and protein epitopes of glycoproteins in serum

Abstract

Aberrant protein glycosylation is associated with a range of pathological conditions including cancer and possesses diagnostic importance. Translation of glycoprotein biomarkers will be facilitated by the development of a rapid and sensitive analytical platform that simultaneously interrogates both the glycan and protein epitopes of glycoproteins in body fluids such as serum or saliva. To this end, we developed an electrochemical biosensor based on the immobilization of a lectin on the gold electrode surface to recognize/capture a target glycan epitope conjugated to glycoproteins, followed by detection of the protein epitope using a target protein-specific antibody. Electrochemical signals are generated by labelfree voltammetric or impedimetric interrogation of a ferro/ferricyanide redox couple (e.g. [Fe(CN) 6 ] 3À/4À ) on the sensing surface, where the change in voltammetric current or interfacial electron transfer resistance was measured. The detection system was demonstrated using the model glycoprotein chicken ovalbumin with Sambucus nigra agglutinin type I (SNA lectin), and exhibits femtomolar sensitivity in the background of diluted human serum. The results obtained in this proof-of-concept study demonstrate the possibility of using electrochemical detection for developing cheap point-of-care diagnostics with high specificity and sensitivity for blood glycoprotein biomarkers.

An electrochemical method for sensitive and rapid detection of FAM134B protein in colon cancer samples

“…They also require high running/maintenance cost, cumbersome and laboratory-based procedures, technical experts, long assay protocol and complicated data analysis, which limits their application in inexpensive and fast point-of-care analysis 14, 15 . Therefore, there is a demand for new assays that can minimize the challenges of conventional detection methods, and will provide non-invasive and quick detection of FAM134B protein.…”

Prostate Cancer Risk-Associated Single-Nucleotide Polymorphism Affects Prostate-Specific Antigen Glycosylation and Its Function

“…Although there may be differences in glycans at other positions including Asn 51 , we observed the same activity, and functional outcomes, from our recombinant yeast PSA variants as with the transfected human PC3 cell line. Thus, using custom designed lectin binding assays to discriminate mannose and fucosyl side chains (33, 34) will allow accurate measurement of the Asn 84 PSA isoform and the WT PSA, respectively. Further, the current calibrants used in clinical assays are not appropriate for the Asn 84 isoform.…”

Employing an Intercalated Redox Reporter in Electrochemical Aptamer-Based Biosensors to Enable Calibration-Free Molecular Measurements in Undiluted Serum

“…The development of a diagnostic approach for a specific target molecule directly in a complex matrix (such as blood, serum, urine, etc.) promises the early diagnosis of diseases and health monitoring. − Toward this goal, we and others have developed electrochemical aptamer-based (E-AB) sensors, a platform supporting the detection of small molecules, proteins, and metal ions. − E-AB sensors exploit an electrode-bound, redox reporter-modified aptamer as their recognition element. The binding of the target molecule to the aptamer results in its conformational change, which alters the efficiency with which the redox reporter approaches the electrode surface, thus producing a readily measurable signal using an electrochemical method such as square wave voltammetry .…”