A new family of nanospheres is made by complexation of divalent Metals (i.e., Ca2+, Ba2+) and poly(phenylacetylene) polymers bearing alpha-methoxyphenyl-acetic acid (MPA) pendants with high content of the cis isomer responsible for their helical. structures. The resulting helical polymer metal complex (HPMC) nanospheres present two interesting, properties (a) their diameter can be tuned to different sizes to growth or to shrink, by changing the metal ion or the polymer/metal ion ratio, and (b) the helicity on the. surface and the interior of the particle can be tuned to any of the two helical senses (M or P) by selection of the metal ion. The role of the solvent, the metal ion and the helicity of the polymer in the aggregation are discussed. The ability of these nanospheres to encapsulate is demonstrated with examples.