title: Simultaneous monitoring of insulin and islet amyloid polypeptide secretion from islets of Langerhans on a microfluidic device.
abstract: A method was developed that allowed simultaneous monitoring of the acute secretory dynamics of insulin and islet amyloid polypeptide (IAPP) from islets of Langerhans using a microfluidic system with two-color detection. A flow-switching feature enabled changes in the perfusion media within 5 s, allowing rapid exchange of the glucose concentrations delivered to groups of islets. The perfusate was continuously sampled by electroosmotic flow and mixed online with Cy5-labeled insulin, fluorescein isothiocyanate (FITC)-labeled IAPP, anti-insulin, and anti-IAPP antibodies in an 8.15 cm mixing channel maintained at 37 °C. The immunoassay mixture was injected for 0.3 s onto a 1.5 cm separation channel at 11.75 s intervals and immunoassay reagents detected using 488 and 635 nm lasers with two independent photomultiplier tubes for detection of the FITC and Cy5 signal. RSD of the bound-to-free immunoassay ratios ranged from 2 to 7% with LODs of 20 nM for insulin and 1 nM for IAPP. Simultaneous secretion profiles of the two peptides were monitored from groups of 4-10 islets during multiple step changes in glucose concentration. Insulin and IAPP were secreted in an approximately 10:1 ratio and displayed similar responses to step changes from 3 to 11 or 20 mM glucose. The ability to monitor the secretory dynamics of multiple peptides from islets of Langerhans in a highly automated fashion is expected to be a useful tool for investigating hormonal regulation of glucose homeostasis.
authors.affiliation: Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States.
authors.forename: Anna R
authors.initials: AR
authors.lastname: Lomasney
authors.forename: Lian
authors.initials: L
authors.lastname: Yi
authors.forename: Michael G
authors.initials: MG
authors.lastname: Roper
mesh_terms: D000818:Animals; D007328:Insulin / Q000032:analysis*; D058228:Islet Amyloid Polypeptide / Q000032:analysis*; D007515:Islets of Langerhans / Q000737:chemistry*; D057230:Limit of Detection; D008297:Male; D051379:Mice; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*
chemical_list: D007328:Insulin; D058228:Islet Amyloid Polypeptide