Homogeneous Insulin and C-Peptide Sensors for Rapid Assessment of Insulin and C-Peptide Secretion by the Islets

• Published in: Diabetes (New York, N.Y.) Vol. 59; no. 10; pp. 2360 - 2365
• Main Authors: HEYDUK, Ewa, MOXLEY, Michael M, SALVATORI, Alison, CORBETT, John A, HEYDUK, Tomasz
• Format: Journal Article
• Language: English
• Published: Alexandria, VA American Diabetes Association 01-10-2010
• Subjects: Antibodies; Antigenic determinants; Base Sequence; Biological and medical sciences; Biosensing Techniques; C-Peptide - analysis; C-Peptide - genetics; C-Peptide - metabolism; Care and treatment; Cloning; Diabetes; Diabetes mellitus; Diabetes. Impaired glucose tolerance; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Enzyme-Linked Immunosorbent Assay; Etiopathogenesis. Screening. Investigations. Target tissue resistance; Glucose; Health aspects; Humans; Insulin; Insulin - analysis; Insulin - genetics; Insulin - metabolism; Insulin Secretion; Islets of Langerhans - metabolism; Limit of Detection; Medical sciences; New Methodologies and Databases; Oligodeoxyribonucleotides - chemistry; Peptides; Proinsulin - analysis; Proinsulin - metabolism; Radioimmunoassay; Research design; Risk factors; Sensors; Endocrinopathy; Pancreatic hormone; Secretion; Insulin; C-Peptide; Diabetes mellitus
• ISSN: 0012-1797; 1939-327X
• DOI: 10.2337/db10-0088

Glucose-stimulated islet insulin or C-peptide secretion experiments are a fundamental tool for studying and assessing islet function. The goal of this work was to develop Ab-based fluorescent homogenous sensors that would allow rapid, inexpensive, near-instantaneous determinations of insulin and C-peptide levels in biological samples.
Our approach was to use molecular pincer design (Heyduk et al., Anal Chem 2008;80:5152-5159) in which a pair of antibodies recognizing nonoverlapping epitopes of the target are modified with short fluorochrome-labeled complementary oligonucleotides and are used to generate a fluorescence energy transfer (FRET) signal in the presence of insulin or C-peptide.
The sensors were capable of detecting insulin and C-peptide with high specificity and with picomolar concentration detection limits in times as short as 20 min. Insulin and C-peptide levels determined with the FRET sensors showed outstanding correlation with determinations performed under the same conditions with enzyme-linked immunosorbent assay. Most importantly, the sensors were capable of rapid and accurate determinations of insulin and C-peptide secreted from human or rodent islets, verifying their applicability for rapid assessment of islet function.
The homogeneous, rapid, and uncomplicated nature of insulin and C-peptide FRET sensors allows rapid assessment of β-cell function and could enable point-of-care determinations of insulin and C-peptide.