Solution composition impacts fibronectin immobilization on carboxymethyl-dextran surfaces and INS-1 insulin secretion

It is shown that solution composition during immobilization plays a critical role in the properties of fibronectin (FN) surfaces and their bioactivity towards insulinoma (INS-1) cell function. X-ray photoelectron spectroscopy revealed FN grafting onto low-fouling carboxymethyl-dextran (CMD) surfaces was successful with solutions composed of 10 μM CaCl2, 10 μM MgCl2, 10 μM MnCl2, and 10 μM and 1 mM NaCl, but unsuccessful with those made of 150 mM NaCl or 1× PBS. Circular dichroism and photon correlation spectroscopy revealed that regardless of solution composition, no measurable differences in free FN conformation prevail. AFM imaging of FN-CMD revealed, while there are no quantitative differences in surface roughness, there are some subtle qualitative differences in topography. FN surface immobilization scheme does not influence INS-1 cell growth after 3 and 7 days regardless of the underlying substrate or solution composition. INS-1 cell insulin secretion in response to glucose is affected by the substrate and solution composition during FN immobilization.

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► Fibronectin (FN) exposed to low-fouling carboxymethyl dextran (CMD) surfaces.
► Only FN solutions with low salt concentration resulted in FN immobilization to CMD.
► Insulinoma (INS-1) cells were seeded to FN-CMD and FN-Glass surfaces.
► INS-1 cell growth uninfluenced by solution composition during FN immobilization.
► FN solution composition impacts INS-1 insulin secretion in response to glucose.