Silica
nanostructures find applications in drug delivery, catalysis,
and composites, however, understanding of the surface chemistry, aqueous
interfaces, and biomolecule recognition remain difficult using current
imaging techniques and spectroscopy. A silica force field is introduced
that resolves numerous shortcomings of prior silica force fields over
the last 30 years and reduces uncertainties in computed interfacial
properties relative to experiment from several 100% to less than 5%.
In addition, a silica surface model database is introduced for the
full range of variable surface chemistry and pH (Q<sup>2</sup>, Q<sup>3</sup>, Q<sup>4</sup> environments with adjustable degree of ionization)
that have shown to determine selective molecular recognition. The
force field enables accurate computational predictions of aqueous
interfacial properties of all types of silica, which is substantiated
by extensive comparisons to experimental measurements. The parameters
are integrated into multiple force fields for broad applicability
to biomolecules, polymers, and inorganic materials (AMBER, CHARMM,
COMPASS, CVFF, PCFF, INTERFACE force fields). We also explain mechanistic
details of molecular adsorption of water vapor, as well as significant
variations in the amount and dissociation depth of superficial cations
at silica–water interfaces that correlate with ζ-potential
measurements and create a wide range of aqueous environments for adsorption
and self-assembly of complex molecules. The systematic analysis of
binding conformations and adsorption free energies of distinct peptides
to silica surfaces will be reported separately in a companion paper.
The models aid to understand and design silica nanomaterials in 3D
atomic resolution and are extendable to chemical reactions