Folate-conjugated self-assembling block copolymers of modulated block length: a new strategy for surface decoration of nanoparticles

In the present communication, we describe a route of synthesis aimed to selectively obtain PCL-PEG-?Fol copolymer with high yield and purity. It is note from literature that only ?-folate conjugates retain affinity towards the receptor. Synthesis of PCL-PEG-?Fol copolymer was optimized in terms of yield, purity and feasibility. We demonstrate that the extent of specific internalization of targeted NPs can be improved by regulating the length of the PEG chains in PCL-PEG to attain stealth properties (1000 Da) and in PCL-PEG-Fol to ameliorate Fol exposition on NP surface (1500 Da). Formulations of NPs using amphiphilic copolymers with different length of PEG blocks turned to be a good strategy to enhance exposition of Folate on the surface of NPs. In fact, the use of short-long PEG blocks length resulted in a significant receptor specific endocytosis.