A composition including a collapsed, polymer nanoparticle and at least one organic, neutral compound associated with the nanoparticle, wherein the nanoparticle is less than 100 nm in diameter, and the polymer comprises a water-soluble polyelectrolyte, has a molecular weight of at least about 100,000 Dalton and is cross-linked. The organic, neutral compound is selected from the group consisting of dyes, pigments, colorants, oils, UV-light absorbing molecules, fragrances, flavoring molecules, preservatives, electro-conductive compounds, thermoplastic compounds, adhesion promoters, penetration enhancers, anti-corrosive agents, and combinations thereof.