title: Self-Assembled Monolayers of an Azobenzene Derivative on Silica and Their Interactions with Lysozyme.
abstract: The capability of the photoresponsive isomerization of azobenzene derivatives in self-assembled monolayer (SAM) surfaces to control protein adsorption behavior has very promising applications in antifouling materials and biotechnology. In this study, we performed an atomistic molecular dynamics (MD) simulation in combination with free-energy calculations to study the morphology of azobenzene-terminated SAMs (Azo-SAMs) grafted on a silica substrate and their interactions with lysozyme. Results show that the Azo-SAM surface morphology and the terminal benzene rings' packing are highly correlated with the surface density and the isomer state. Higher surface coverage and the trans-isomer state lead to a more ordered polycrystalline backbone as well as more ordered local packing of benzene rings. On the Azo-SAM surface, water retains a high interfacial diffusivity, whereas the adsorbed lysozyme is found to have extremely low mobility but a relative stable secondary structure. The moderate desorption free energy (∼60 kT) from the trans-Azo-SAM surface was estimated by using both the nonequilibrium-theorem-based Jarzynski's equality and equilibrium umbrella sampling.
authors.affiliation: Dan F. Smith Department of Chemical Engineering, Lamar University , Beaumont, Texas 77710, United States.
authors.forename: Tao
authors.initials: T
authors.lastname: Wei
authors.affiliation: Dan F. Smith Department of Chemical Engineering, Lamar University , Beaumont, Texas 77710, United States.
authors.forename: Md Symon Jahan
authors.initials: MS
authors.lastname: Sajib
authors.affiliation: Dan F. Smith Department of Chemical Engineering, Lamar University , Beaumont, Texas 77710, United States.
authors.forename: Mohammadreza
authors.initials: M
authors.lastname: Samieegohar
authors.affiliation: Dan F. Smith Department of Chemical Engineering, Lamar University , Beaumont, Texas 77710, United States.
authors.forename: Heng
authors.initials: H
authors.lastname: Ma
authors.affiliation: Mork Family Department of Chemical Engineering and Materials Science, University of Southern California , Los Angeles, California 90089, United States.
authors.forename: Katherine
authors.initials: K
authors.lastname: Shing
mesh_terms: D000327:Adsorption; D001391:Azo Compounds / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D004058:Diffusion; D008958:Models, Molecular; D009113:Muramidase / Q000737:chemistry* / Q000378:metabolism; D010316:Particle Size; D012822:Silicon Dioxide / Q000737:chemistry* / Q000378:metabolism; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D001391:Azo Compounds; D014867:Water; D012822:Silicon Dioxide; D009113:Muramidase; C009850:azobenzene