[Zinc-modified Nanotransporter for Target Drug Therapy of Breast Cancer]

In the centre of nanomedical interest stands the nanotechnological modification of anthracycline antibiotics, which are often used in antitumor treatment of hematological malignancies and solid tumors. Chitosan nanoparticles are gaining more attention in the field of targeted transport of drugs because of their stability, low toxicity and simple preparation. The main objective of the project, was the design of chitosan nanotransporter of anthracycline antibiotics with zinc modified surface, for a specific interaction with metallothionein.

The chitosan nanoparticles with encapsulated doxorubicin were prepared by a dissolution of 5g of chitosan in 3% solution of acetic acid and TPP (0.25% w/v) and doxorubicin (0.5mg/ml). Fe2O3-NPs were prepared by a reduction with borohydride and using ammonia. Thereafter Fe2O3-AuNPs were prepared by thermal synthesis. The amount of doxorubicin and Zn2+ was determined using DPV.

Chitosan nanotransporter with anthracycline antibiotics (CHIT-Zn-DOXO-Fe2O3-AuNPs) was designed and subsequently studied by biophysical methods. Inside of the nanometric structure is electrostatically bound doxorubicin (concentration 10 µM, CHIT-DOXO). Moreover metallothionein is a molecule rich in cysteine and thanks to its free sulphhydryl groups is capable of bonding with the zinc ions. We have decided to use this ability for a construction of the nanotransporter for its targeted direction towards the tumor tissue (CHIT-Zn-DOXO). We have shown significant increases of a metallothionein (MT) level in malignant tumors in many of our previous experiments. MT into its domains binds heavy metal ions (naturally zinc ions) and keeps the homeostasis in equilibrium this way. Therefore we have decided to observe the ability of modified chitosan nanoparticles (CHIT-Zn-DOXO, 100 µg/ml) for MT protein binding (magnetic gold nanoparticles were modified by MT, 100 µg/ml, Fe2O3-AuNPs) in the other part of our experiment. The efficiency of the chitosan nanoparticle bond modified by zinc ions (CHIT-Zn-DOXO) to the MT (CHIT-Zn-DOXO-Fe2O3-AuNPs-MT) increased by more than 30% compared with the unmodified nanoparticle (CHIT-DOXO).

We assume that the new nanotransporter is specific for its bioavailability, increased uptake of the drug from bloodstream in the tumor tissue area and low toxicity for an untargeted tissue.Key words: chitosan - magnetic gold nanoparticles - breast cancer - doxorubicin The work was realized with the support of the project NANODRUGS 328/2017/FaF and The European Technology Platform for Nanomedicine. The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 6. 3. 2017Accepted: 26. 3. 2017.