Abstract: A method and kit is described for the detection of a biomarker in a sample, by light scattering microscopy. The invention is particularly useful for the detection of low abundance biomarker in complex samples, and is suitable for use in a point of care setting. In an embodiment, the method of the invention describes detection of a biomarker in a sample using mass photometry.

Abstract: The application discloses a method and apparatus for imaging a sample by interferometric scattering microscopy, the method comprising illuminating a sample with at least one coherent light source, the sample being held at a sample location comprising an interface having a refractive index change, illuminating the sample with illuminating radiation to generate a backpropagating signal from the sample comprising light reflected at the interface and light scattered by the sample, splitting the backpropagating signal into first and second signals, modifying the second signal using a modifying element such that the second signal differs from the first signal, directing the first and second signals onto first and second detectors to generate, respectively, first and second images and comparing, by a processor, the first and second images to determine one or more characteristics of the sample.