Immobilization in single-particle tracking (SPT): escape from the point spread function (PSF) of the microscope

Abstract

A key idea in SPT analysis is that the pure unhindered random walk is the null hypothesis. To claim that a diffusing tracer particle is doing something, one must evaluate, informally or formally, the probability that similar behavior would occur by chance in a pure random walk of the same duration. One biophysically important behavior of a tracer is immobilization. Immobilization is usually defined in terms of noise, specifically the observed scatter of positions of a tracer physically immobilized on the slide.