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 PEGylated-lipid (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 C16-PEG(2000Da)-Ceramide-SWCNTs optical response is excitation-wavelength dependent, where resonant excitation leads to a larger fluorescence decrease in response to insulin. 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 (ELISA). 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.

Dendron-Polymer Hybrids as Tailorable Coronae of Single-Walled Carbon Nanotube

“…Corona-based recognition was reported for different types of analytes, including small biomolecules, 25,27 and even proteins. [28][29][30] The importance of the nature of the exposed, hydrophilic part of the dispersant in forming an analytespecific corona phase is evident, but previous publications reveal that the corona phase is also influenced by its hydrophobic anchor unit, attached to the SWCNTs. For the recognition of fibrinogen, SWCNTs suspended by a polyethylene glycol (PEG) polymer coupled to a phospholipid with a chain length of 16 carbon atoms were found to have the highest optical response, while coupling to a phospholipid with 14 or 18 carbon atoms showed significantly weaker response.…”

Dendron-Polymer Hybrids as Tailorable Coronae of Single-Walled Carbon Nanotube

“…Corona-based recognition was reported for different types of analytes, including small biomolecules, 25,27 and even proteins. [28][29][30] The importance of the nature of the exposed, hydrophilic part of the dispersant in forming an analytespecific corona phase is evident, but previous publications reveal that the corona phase is also influenced by its hydrophobic anchor unit, attached to the SWCNTs. For the recognition of fibrinogen, SWCNTs suspended by a polyethylene glycol (PEG) polymer coupled to a phospholipid with a chain length of 16 carbon atoms were found to have the highest optical response, while coupling to a phospholipid with 14 or 18 carbon atoms showed significantly weaker response.…”