Previous resultsr evealed that arsenic trioxide might be used as promising therapeutic agent for the treatment of some solid tumoursa sa typical teratoid rhabdoid tumours (ATRT). However,i no rder to becomea na pproved drug for solid tumour treatment, the active formulation has to get more efficient and feasible-buta tt he same time less toxic. One of the possibilities to achieve this dichotomy is to use nanomedicine tools. Herein, we report on the Znbased metal-organicf ramework ZIF-8 (Zeolitic Imidazolate Framework-8) which turned out to be ap romising candidate for the delivery of As III species. It conjointly features ah igh drug loading capacity and ap rominent pH-triggered release behaviour.A s III -loaded ZIF-8 nanoparticlesc oated and noncoatedw ith polyethylene glycol weres tudied by XRPD, IR, Raman, TGA, TEM, EDX, CHN-elemental analysis, sorption analysisa nd ICP-OES, and their cytotoxicity was evaluated in vitro.