Cellular biophysical dynamics and ion channel activities detected by AFM-based nanorobotic manipulator in insulinoma β-cells

Distinct biochemical, electrochemical and electromechanical coupling processes of pancreatic β-cells may well underlie different response patterns of insulin release from glucose and capsaicin stimulation. Intracellular Ca2 + levels increased rapidly and dose-dependently upon glucose stimulation, accompanied with about threefold rapid increases in cellular stiffness. Subsequently, cellular stiffness diminished rapidly and settled at a value about twofold of the baseline. Capsaicin caused a similar transient increase in intracellular Ca2 + changes. However, cellular stiffness increased gradually to about twofold until leveling off. The current study characterizes for the first time the biophysical properties underlying glucose-induced biphasic responses of insulin secretion, distinctive from the slow and single-phased stiffness response to capsaicin despite similar changes in intracellular Ca2 + levels. The integrated AFM nanorobotics and optical investigation enables the fine dissection of mechano-property from ion channel activities in response to specific and non-specific agonist stimulation, providing novel biomechanical markers for the insulin secretion process.From the Clinical EditorThis study characterizes the biophysical properties underlying glucose-induced biphasic responses of insulin secretion. Integrated AFM nanorobotics and optical investigations provided novel biomechanical markers for the insulin secretion process.

Graphical AbstractDynamic characterization of cellular stiffness simultaneously with [Ca2 +]i fluorescence imaging after glucose stimulation. The kinetics of ion channel activities overlaps with the cellular stiffness change in the first phase when the onset of stimulation induced rapid structural rearrangement. A second sustained phase follows to maintain the stiffness at a relatively higher level (A). A close look at the lagging of stiffness response compared with that of Ca2 +, a 2-min delay was observed (B). The fluorescence imaging of [Ca2 +]i before stimulation (C), 12 min after when the light intensity reaches the peak (D), and 20 min after (E) when the light intensity falls to the baseline.Figure optionsDownload high-quality image (200 K)Download as PowerPoint slide