The biological surface adsorption index (BSAI) is a novel approach to characterize surface
adsorption energy of nanomaterials that is the primary force behind nanoparticle aggregation,
protein corona formation, and other complex interactions of nanomaterials within biological
systems. Five quantitative nanodescriptors were obtained to represent the surface adsorption
forces (hydrophobicity, hydrogen bond, polarity/polarizability, and lone-pair electrons) of the
nanomaterial interaction with biological components. We have mapped the surface adsorption
forces over 16 different nanomaterials. When the five-dimensional information of the
nanodescriptors was reduced to two dimensions, the 16 nanomaterials were classified into
distinct clusters according their surface adsorption properties. BSAI nanodescriptors are
intrinsic properties of nanomaterials useful for quantitative structureactivity relationship
(QSAR) model development. This is the first success in quantitative characterization of the
surface adsorption forces of nanomaterials in biological conditions, which could open a
quantitative avenue in predictive nanomedicine development, risk assessment, and safety
evaluation of nanomaterials.