A method for the preparation of degradable amorphous retinoid/calcium-polyphosphate nanospheres comprises: (i) dissolving a retinoid and a calcium salt in an organic solvent; (ii) adding the retinoid calcium salt solution as produced in step (i) to an aqueous solution containing dissolved polyphosphate (polyp) salt and poly(ethylene glycol) or another lubricating coating material, and (iii) collecting washing with water , and drying of the nanospheres as formed. Preferably the retinoid is retinol. Preferably the chain length of the polyphosphate is in the range of about 3 to about 1000 phosphate units. Preferably the amorphous retinoid/calcium-polyphosphate nanospheres are for use in the treatment or prophylaxis of dermatological conditions, such as inflammatory skin disorders, acne, disorders of increased cell turnover such as psoriasis, skin cancers and photoaging. The amorphous retinol/calcium-polyphosphate nanospheres displayed the following: (i) Homogenous size in a range (~45 nm) optimal for cellular uptake by clathrin-mediated endocytosis; (ii) Synergistic effect of both components, retinol and polyphosphate, at non-effective concentrations of the individual components, on cell proliferation and collagen expression (types I, II, and III); (iii) Pronounced synergistic effect on expression of collagen type III; (iv) Disintegration by extracellular enzymatic hydrolysis; (v) Dual biological effect of polyP and retinol, both via the extracellular and via the intracellular route; and (vi) No cytotoxicity.
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