Abstract: A coating material and a method for coating a hydrophobic membrane with a copolymer that contains at least one hydrophilic segment and at least one hydrophilic segment, such as a PEO—PPO—PEO triblock copolymer, so that the surface of the membrane becomes hydrophilic. The hydrophilic coating helps repel biological molecules, thereby reducing the risk that these molecules will adsorb or deposit on the membrane surface. When the copolymers are modified with an active group, ligands can be immobilized on the copolymer through the active group so that specific molecules that will bind with the ligands can be targeted for immobilization on the copolymer coating, thereby improving the efficiency of the removal of specific targets.

Abstract: The method for mapping a mechanical property of a surface of a sample with a scanning force microscope comprises the steps of (a) scanning a fine tip in contact with the surface of the sample within a predetermined scan area, the fine tip being supported on an end of a cantilever beam, (b) applying a loading force on the surface of the sample by the fine tip, (c) using a constant frequency sine wave to oscillate the cantilever beam relative to the surface of the sample, (d) measuring a detector response of the fine tip at the end of the cantilever beam, (e) determining an amplitude of the detector response and a change in phase angle of the detector response relative to the sine wave used to oscillate the cantilever beam, and (f) relating the amplitude and the change in phase angle to a property of the surface of the sample. A feedback system is utilized which regulates the total force imposed by the fine tip onto the surface of the sample so that the amplitude of the detector response is maintained constant.