title: Molecular dynamics simulations on the effect of size and shape on the interactions between negative Au18(SR)14, Au102(SR)44and Au144(SR)60nanoparticles in physiological saline.
abstract: Molecular dynamics simulations employing all-atom force fields have become a reliable way to study binding interactions quantitatively for a wide range of systems. In this work, we employ two recently developed methods for the calculation of dissociation constantsKDbetween gold nanoparticles (AuNPs) of different sizes in a near-physiological environment through the potential of mean force (PMF) formalism: the method of geometrical restraints developed by Woo et al. and formalized by Gumbart et al. and the method of hybrid Steered Molecular Dynamics (hSMD). Obtaining identical results (within the margin of error) from both approaches on the negatively charged Au18(SR)14NP, functionalized by the negatively charged 4-mercapto-benzoate (pMBA) ligand, we draw parallels between their energetic and entropic interactions. By applying the hSMD method on Au102(SR)44and Au144(SR)60, both of them near-spherical in shape and functionalized by pMBA, we study the effects of size and shape on the binding interactions. Au18binds weakly withKD= 13mMas a result of two opposing effects: its large surface curvature hindering the formation of salt bridges, and its large ligand density on preferential orientations favoring their formation. On the other hand, Au102binds more strongly withKD= 30μMand Au144binds the strongest withKD= 3.2nM.
authors.affiliation: Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, Texas 78249, U.S.A.
authors.forename: Oscar D
authors.initials: OD
authors.lastname: Villareal
authors.affiliation: Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, Texas 78249, U.S.A.
authors.forename: Roberto A
authors.initials: RA
authors.lastname: Rodriguez
authors.affiliation: Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, Texas 78249, U.S.A; Department of Laboratory Medicine, Yancheng Vocational Institute of Health Sciences, Jiangsu Yancheng 224006, P.R.C.
authors.forename: Lili
authors.initials: L
authors.lastname: Yu
authors.affiliation: Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, Texas 78249, U.S.A.
authors.forename: Thierry O
authors.initials: TO
authors.lastname: Wambo
keywords: Aggregation; Gold Nanoparticles; Molecular Dynamics