Virtual separation approach to study porous ultra-thin films by combined spectroscopic ellipsometry and quartz crystal microbalance methods

Dynamic analysis of DNA nanoparticle immobilization to model biomaterial substrates using combinatorial spectroscopic ellipsometry and quartz crystal microbalance with dissipation

“…Combinatorial SE/ QCM-D was used for this investigation since both SE and QCM-D can measure adsorption masses in situ (i.e. real-time), though the adsorbed mass measured by SE is a measure of the mass of only organic constituents of the thin film, while QCM-D measures the adsorbed mass of the organic constituents including entrapped and associated solvent molecules [14,18]. Therefore, any differences reported in SE and QCM-D adsorbed mass for a given treatment do not indicate conflicting measurement results, but rather demonstrate the different components being measured by the two different instruments.…”

“…Detailed accounts of SE/QCM-D data acquisition and modeling can be found in previously published work [14,18]. Briefly, the combinatorial SE/ QCM-D setup consists of an E1 QCM-D module (Q-Sense, Linthicum, MD) mounted to the sample stage of a M-2000 spectroscopic ellipsometer (J.A.…”

“…The Sauerbrey relation was used to calculate the adsorbed mass detected by QCM-D via changes in frequency upon biomolecule adsorption, since the layer of DNA-NPs on the surface was assumed to be a rigid, solid film [14,[16][17][18]. Additionally, for SE/QCM-D data modeling, which is covered in detail in another publication [14], the densities for both the ambient medium (1× TBS) and the organic medium (DNA-NP solution prepared in 1× TBS) were assumed to be 1, since specific gravity data is not available for these solutions.…”

“…While both SE and QCM-D are commonly used separately, only recently have these devices and techniques been combined to form a hybrid measurement platform known as combinatorial in situ SE/QCM-D, which is used to characterize the adsorption processes of a diverse array of organic molecules and thin films [14][15][16][17][18][19]. By combining both measurement systems, new physical parameters of thin films can be elucidated, such as the porosity of a thin film or the amount of entrapped and associated solvent in real time.…”

“…In the combinatorial system, the QCMD sensor provides an interface for studying surface interactions and is mounted within an airtight liquid flow cell, which contains windows for the SE light beam to also probe the QCM-D sensor. Detailed accounts of in situ combinatorial SE/QCM-D experimental and theoretical principles are presented in previously published literature [14,18]. SE/QCM-D can be used as a quick, reliable, and noninvasive tool to accurately monitor adsorption processes and to standardize or optimize substrate immobilization strategies.…”