A method for treating a surface of a plastic substrate, comprising: treating the surface to form a converted surface, in which treating the surface is carried out by: employing a first treatment step that includes remote conditioning treatment of the surface with conditioning plasma of one or more non-polymerizing compounds at a remote point, where the ratio of the radiant energy density at the remote point to the radiant energy density at the brightest point of the conditioning plasma is less than 0.5, alternatively less than 0.25, alternatively substantially zero, alternatively zero; and employing a second treatment step that includes remote conversion treatment of the surface with a conversion plasma of water vapor to form a converted surface, where the ratio of the radiant energy density at the remote point of conversion treatment to the radiant energy density at the brightest point of the conversion plasma is less than 0.5, alternatively less than 0.25, alternatively substantially zero, alternatively zero, wherein the radiant energy density at the brightest point of the plasma is determined spectrophotometrically by measuring the radiant intensity of the most intense emission line of light in the spectrum from 380 nm to 750 nm wavelength at the brightest point, and the radiant energy density at the remote point is determined spectrophotometrically by measuring the radiant energy density of the same emission line of light at the remote point; wherein after the second treatment step the converted surface has a biomolecule recovery percentage greater than the biomolecule recovery percentage of the surface prior to treatment according to the method, wherein the biomolecule recovery percentage is determined according to the method "Testing of all embodiments" described in the description. employing a first treatment step that includes remote conditioning treatment of the surface with conditioning plasma of one or more non-polymerizing compounds at a remote point, where the ratio of the radiant energy density at the remote point to the radiant energy density at the brightest point of the conditioning plasma is less than 0.5, alternatively less than 0.25, alternatively substantially zero, alternatively zero; and employing a second treatment step that includes remote conversion treatment of the surface with a conversion plasma of water vapor to form a converted surface, where the ratio of the radiant energy density at the remote point of conversion treatment to the radiant energy density at the brightest point of the conversion plasma is less than 0.5, alternatively less than 0.25, alternatively substantially zero, alternatively zero, wherein the radiant energy density at the brightest point of the plasma is determined spectrophotometrically by measuring the radiant intensity of the most intense emission line of light in the spectrum from 380 nm to 750 nm wavelength at the brightest point, and the radiant energy density at the remote point is determined spectrophotometrically by measuring the radiant energy density of the same emission line of light at the remote point; wherein after the second treatment step the converted surface has a biomolecule recovery percentage greater than the biomolecule recovery percentage of the surface prior to treatment according to the method, wherein the biomolecule recovery percentage is determined according to the method "Testing of all embodiments" described in the description.