NOVELTY - An anisotropic self-assembled structure has grafted nanoparticle comprising a spherical inorganic core nanoparticle and an organic brush structure grafted to the nanoparticle. The brush structure comprises grafted polymeric chains having a weight average molecular weight.    USE - Anisotropic self-assembled structure for synthetic substitute for bone or tooth enamel; fuel cell; flame-retardant material; or electroconductive material (claimed).    ADVANTAGE - The anisotropic self-assembled structure has superior mechanical properties which provide stronger and more durable structure for bone or tooth repair in patient; has superior structural properties and high ion densities which provide efficient fuel cells; can reduce gas permeability of flame-retardant materials; and can be manufactured with a cost-effective method.    DETAILED DESCRIPTION - An anisotropic self-assembled structure comprises a one-dimensional string of the grafted nanoparticles within the matrix, a two-dimensional sheet of the grafted nanoparticles within the matrix, and three dimensionally interconnected structures where the width of each structure is 1-10 nanoparticles. The string has a width of one nanoparticle and a length of 1-10 nanoparticles. The sheet has a length and a breadth of less than or equal to 1 mu m respectively, where the sheet is 2-5 nanoparticles in thickness. Each grafted nanoparticle comprises a spherical inorganic core nanoparticle and an organic brush structure grafted to the nanoparticle. The brush structure comprises grafted polymeric chains of a weight average molecular weight (Mg). The polymeric matrix has a weight average molecular weight of M. An average number of grafted polymeric chains per nm2 of surface of the inorganic core nanoparticles D is also provided. An INDEPENDENT CLAIM is included for a method for preparing the anisotropic self-assembled structure comprising forming a dispersion of the grafted nanoparticles in the polymeric matrix, then, annealing the residue at a temperature above a glass transition temperature (preferably greater than 200 degrees C) of the polymeric matrix for a time (preferably 1-20 days) to bring formation of the self-assembled structure within the matrix.