*Article* **Poly(Ethylene Glycol)-***b***-Poly(D,L-Lactide) Nanoparticles as Potential Carriers for Anticancer Drug Oxaliplatin**

**Yulia A. Kadina 1, Ekaterina V. Razuvaeva 1,\*, Dmitry R. Streltsov 1, Nikita G. Sedush 1, Eleonora V. Shtykova 2, Alevtina I. Kulebyakina 1, Alexander A. Puchkov 1, Dmitry S. Volkov 3, Alexey A. Nazarov 3 and Sergei N. Chvalun 1,4**


**Abstract:** Nanoparticles based on biocompatible methoxy poly(ethylene glycol)-*b*-poly(D,L-lactide) (mPEG113-*b*-P(D,L)LA*n*) copolymers as potential vehicles for the anticancer agen<sup>t</sup> oxaliplatin were prepared by a nanoprecipitation technique. It was demonstrated that an increase in the hydrophobic PLA block length from 62 to 173 monomer units leads to an increase of the size of nanoparticles from 32 to 56 nm. Small-angle X-ray scattering studies confirmed the "core-corona" structure of mPEG113-*b*-P(D,L)LA*n* nanoparticles and oxaliplatin loading. It was suggested that hydrophilic oxaliplatin is adsorbed on the core-corona interface of the nanoparticles during the nanoprecipitation process. The oxaliplatin loading content decreased from 3.8 to 1.5% wt./wt. (with initial loading of 5% wt./wt.) with increasing PLA block length. Thus, the highest loading content of the anticancer drug oxaliplatin with its encapsulation efficiency of 76% in mPEG113-*b*-P(D,L)LA*n* nanoparticles can be achieved for block copolymer with short hydrophobic block.

**Keywords:** poly(lactide); poly(ethylene glycol); block copolymers; self-assembly; nanoparticles; drug delivery systems; anticancer agen<sup>t</sup>
