ADSA-TRIS: a new method to study interfacial phenomena at polymer–aqueous solution interfaces

Abstract

Axisymmetric drop shape analysis-profile (ADSA-P) was combined with total reflectometric interference spectroscopy (TRIS) in one experimental setup to study the interfacial phenomena at solid-liquid and liquid-vapor interfaces caused by adsorption/desorption (dissolution) of surface-active substances. Using sessile liquid droplets on polymer film/chromium-coated glass substrates that were optically matched with an immersion oil to a TRIS reflection prism, the optical thickness (product of physical thickness d and refractive index n) of the polymer film can be estimated by evaluating the wavelength-dependent intensity of reflected light. The sessile droplet is analyzed simultaneously by an ADSA setup arranged in a transverse direction to the path of the white-light beam of TRIS. From this analysis, the solid-vapor interfacial tension gamma (lv)(t), contact angle theta(t), contact radius r(t), drop volume V(t), and solid-liquid interfacial tension gamma (sl)(t) can be monitored as a function of time. The new method was applied to study polystyrene and poly(4-hydroxystyrene) surfaces in contact with aqueous buffer solutions and with protein solutions. The time-dependent changes in the optical film thickness caused by the adsorption of human serum albumin (HSA) and lysozyme (LSZ) were accompanied by changes in the solid-liquid interfacial tension. From the detailed study of both parameters, conclusions can be drawn with regard to the adsorption kinetics of the proteins on the hydrophobic polystyrene surfaces and to conformational changes occurring within the adsorbed protein layers.

Simultaneous Measurement of Contact Angle and Surface Tension Using Axisymmetric Drop-Shape Analysis-No Apex (ADSA-NA)

“…A number of methods have been developed for the measurement of contact angles and surface tensions. − There are some situations in which the simultaneous measurement of the contact angle and surface tension is necessary, for instance, in studies concerning the effect of the adsorption of surface-active substances on solid−liquid and liquid−vapor interfacial tension − or in studies concerning the measurement of the work of adhesion in molten alloy−ceramic substrate systems. − Among the methods of contact angle and surface tension measurement, the combination of the capillary rise method and the Wilhelmy method, as well as drop-shape techniques, is capable of simultaneous measurements.…”

Two Decades of Arrayed Imaging Reflectometry for Sensitive, High-Throughput Biosensing

“…Over the past few decades, several label-free biosensing technologies have been developed based on operating principles of interferometry or reflectometry. These techniques, close relatives of spectroscopic ellipsometry, include arrayed imaging reflectometry (AIR) [ 1 ], biolayer interferometry (BLI) [ 2 , 3 ], the interferometric reflectance imaging sensor (IRIS) [ 4 , 5 ], reflectometric interference spectroscopy (RIfS) [ 6 ], 1λ reflectometry [ 7 ], oblique-incidence reflectivity difference microscopy (OI-RD) [ 8 , 9 ], and total reflectometric interference spectroscopy (TRIS) [ 10 ]. A broad overview of these methods may be found in a recent review by Fechner et al [ 11 ].…”