Patent ID: 8361508

Claim:
A method of enhancing an endocytosis of an active agent into a cell having surface receptors, comprising: obtaining particles comprising the active agent and surface moieties that have an affinity for or are capable of binding to the receptors, wherein the particles have a radius no less than an endocytotic threshold radius that is based on (a) a surface density of the receptors, (b) a surface density of the moieties and (c) one or more interaction parameters, including at least one of a non-specific interaction strength between the cell and one of said particles selected from the group consisting of decay length (δ), ligand-receptor natural length (ξ), ligand-receptor spring constant (k), ligand-receptor binding energy (C) and stiffness (σ), and wherein the particles have a radius that is from 0.7 to 1.3 of the particles' endocytosis maximizing radius; and interacting the cell with the particles, wherein the interacting enhances the endocytosis.