Optical Nanosensors for Real‐Time Feedback on Insulin Secretion by β‐Cells

Abstract

Quantification of insulin is essential for diabetes research in general, and for the study of pancreatic β‐cell function in particular. Herein, fluorescent single‐walled carbon nanotubes (SWCNT) are used for the recognition and real‐time quantification of insulin. Two approaches for rendering the SWCNT sensors for insulin are compared, using surface functionalization with either a natural insulin aptamer with known affinity to insulin, or a synthetic lipid‐poly(ethylene glycol) (PEG) (C16‐PEG(2000Da)‐Ceramide), both of which show a modulation of the emitted fluorescence in response to insulin. Although the PEGylated‐lipid has no prior affinity to insulin, the response of C16‐PEG(2000Da)‐Ceramide‐SWCNTs to insulin is more stable and reproducible compared to the insulin aptamer‐SWCNTs. The SWCNT sensors successfully detect insulin secreted by β‐cells within the complex environment of the conditioned media. The insulin is quantified by comparing the SWCNTs fluorescence response to a standard calibration curve, and the results are found to be in agreement with an enzyme‐linked immunosorbent assay. This novel analytical tool for real time quantification of insulin secreted by β‐cells provides new opportunities for rapid assessment of β‐cell function, with the ability to push forward many aspects of diabetes research.

Biosensing with Fluorescent Carbon Nanotubes

“…This study highlights the urgent need to investigate sensors not only in simple buffers but biologically complex environments.M ost recently,E hrlich et al developed ac omplementary approach using an insulin aptamer (found within the natural insulin gene promoter) functionalized to the SWCNT surface through a( AT) 15 ssDNAa nchor sequence. [158] In contrast to the synthetic PEGylated-lipid, which has no prior affinity to insulin, this aptamer possesses ak nown affinity to insulin. However,t he observed sensitivity was lower than the previous approach.…”

Biosensing with Fluorescent Carbon Nanotubes

“…Most recently, Ehrlich et al. developed a complementary approach using an insulin aptamer (found within the natural insulin gene promoter) functionalized to the SWCNT surface through a (AT) 15 ssDNA anchor sequence [158] . In contrast to the synthetic PEGylated‐lipid, which has no prior affinity to insulin, this aptamer possesses a known affinity to insulin.…”

Monitoring the Activity and Inhibition of Cholinesterase Enzymes using Single-Walled Carbon Nanotube Fluorescent Sensors

“…Thus, we monitored the fluorescence response of the DNA-SWCNT sensors to different concentrations of both AChE and BChE between 10 −4 and 10 2 U L −1 well within the relevant window for characterizing enzymatic activity and inhibition in the body. 66 The concentration-dependent normalized fluorescence response was fitted by a four parameter logistic regression with a zero baseline, resulting in a three-parameter fit, 45,46…”