Gene expression within cells can be altered through gene delivery approaches, which have tremendous potential for gene therapy, tissue engineering, and diagnostics. Substrate-mediated gene delivery describes the delivery of plasmid DNA or DNA complexed with nonviral vectors to cells from a surface, with the DNA immobilized to a substrate through specific or nonspecific interactions. In this work, DNA-nanoparticle (DNA-NP) adsorption to substrates is evaluated using combinatorial, in situ spectroscopic ellipsometry and quartz crystal microbalance with dissipation (SE/QCM-D), to evaluate the basic dynamic processes involved in the adsorption and immobilization of DNA-NP complexes to substrates. The concentration of DNA-NP solutions influences the adsorbed DNA-NP surface mass, which increases by a factor of approximately 6 (detected by SE) and approximately 4.5-fold (detected by QCM-D), as the DNA concentration increases from 1.5 mu g/mL to 15 mu g/mL, with an increase in layer porosity. In addition, SE/QCM-D analysis indicates that DNA-NP adsorption rates, surface coverage densities, and volume fractions are dependent on the type of substrate: gold (Au) and silicon dioxide substrates, protein-coated and uncoated substrates, and surfaces modified with alkanethiol self assembled monolayers (SAMs). These studies also demonstrate that the influence of an adsorbed protein layer on resulting DNA-NP immobilization efficiency is substrate dependent. For example, Au surfaces coated with fetal bovine serum (FBS) resulted in two-fold greater mass of adsorbed DNA-NPs, compared to DNA-NP adsorption to FBS-coated SAM substrates. This investigation offers insights into dynamic DNA-NP surface adsorption processes, characteristics of the immobilized DNA-NP layer, and demonstrates substrate-dependent DNA-NP adsorption. (C) 2014 Elsevier B.V. All rights reserved.