Abstract: Provided is a method for permeabilising a viable cell having a cell wall, comprising: (a) pressurising a fluid or gel in contact with a surface of the cell; and (b) depressurising the fluid or gel; to form at least one hole in a surface of the cell.

Abstract: Provided is a method for introducing a substance into a cell, which method comprises: (a) generating one or more bubbles of a gas in a liquid medium comprising the cell, the bubbles being capable of forming a hole in the surface of the cell when one or more bubbles interact with the cell; and (b) introducing the substance into the cell.

Abstract: Provided is a method for introducing a substance into a cell, which method comprises: (a) contacting the cell with a recognition agent to bind the recognition agent to a recognition site on the surface of the cell; and (b) separating the recognition agent from the cell thereby forming a hole in the surface of the cell. Kits for use in such methods are also provided.

Abstract: A fixed-angle rotor, having a centrifuge tube inclined at a predetermined gradient angle with respect to a rotational axis, is used to obtain a sedimentation coefficient of sample particles. In one method, a distance in the centrifugal direction is corrected by the gradient angle .theta. of centrifuge tube 1. Sedimentation coefficient S.sub.20,W is calculated based on the corrected distance, and then the sedimentation coefficient S.sub.20,W is multiplied with sin(.theta.) to obtain a corrected sedimentation coefficient. In another method, a distance in the centrifugal direction is corrected by the gradient angle .theta., and also an angular acceleration .omega..sup.2 is corrected by dividing it by sin(.theta.). And then, the sedimentation coefficient S.sub.20,W is calculated based on thus corrected distance and corrected angular acceleration.