Water soluble poly(3-hydroxyalkanoate) containing ionic groups was designed by two successive photo-activated thiol-ene reactions. Sodium-3-mercapto-1-ethanesulfonate (SO3-) and poly(ethylene glycol) methyl ether thiol (PEG) were grafted onto poly(3-hydroxyoctanoate-co-3-hydroxyundecenoate) PHO(67)U(33) to both introduce ionic groups and hydrophilic moieties. The grafted copolymers PHO(67)SO3-(20)PEG(13) were then used as biocompatible coatings of nano-Metal Organic Frameworks surface. Scanning Electron Microscopy and Scanning Transmission Electron Microscopy coupled with Energy Dispersive X-ray characterizations have clearly demonstrated the presence of the copolymer on the MOF surface. These coated nano-MOF are stable in aqueous and physiological fluids. Cell proliferation and cytotoxicity tests performed on murine macrophages J774.A1 revealed no cytotoxic side effect. Thus, biocompatibility and stability of these novel hybrid porous MOF structures encourage their use in the development of effective therapeutic nanoparticles.