Eumelanin like materials are known to be heterogeneous and highly insoluble materials and hence it was difficult to use them for applications even if they display fascinating properties as photoprotection and photoconductivity. Owing to the known reactivity of quinones available on the surface of dopamine-eumelanin particles with nucleophiles, we propose and demonstrate that proteins (among them human serum albumin, hen egg white lysozyme and alpha-lactalbumine from bovine milk) are able to control the size of dopamine-eumelanin aggregates formed in dopamine solutions upon oxidation. The particles obtained in the presence of human serum albumin can be as small as 30 nm in diameter and the viability of human gingival fibroblasts is not significantly affected (with respect to pure dopamine-eumelanin) in the presence of such particles provided they are diluted enough. (C) 2013 Elsevier Inc. All rights reserved.