The present invention in particular relates to the field of micro- and nanoparticles, more in particular to coated nanoparticles. The coatings of the present invention in particular comprise surfactant protein B (SP-B) and one or more lipids. The invention further relates to such coated particles and compositions comprising them for use as a medicament, in particular for use in the treatment of various disorders. Furthermore, the invention provides the use of the compositions of the current invention for delivering one or more agents, such as small interfering RNA (siRNA) molecules, to the target tissue or cells.