(678c) Paramagnetic Cations-Loaded Polydopamine Nanoparticles Cytotoxicity

Melanins are natural occurring biopolymers with different functions in the organisms in which they are present. Among these functions, skin UV protection is perhaps the most recognized. However, they participate in many other biological processes, as the regulation of the cellular concentration of free metallic ions, being able of sequestering them or acting as an ion reservoir [1,2].

Taking into account this fact, polydopamine, a synthetic melanin analogous, has acquired an important role in material science [3]. Since its ability to chelate paramagnetic cations is known, it has been considered to device MRI contrast agents or more advanced theranostic systems. In this line, several studies have demonstrated polydopamine biocompatibility during the first 24 hours of treatment, but its long-time cytotoxicity has not been studied yet [4].

Thus, in the present work, the interaction of polydopamine particles with different cations (Fe²⁺, Fe³⁺, Ca²⁺, Na⁺, Zn²⁺ and Cu²⁺) has been carried out, analyzing their metal loading capacity and affinity. A tentative assignation for such metal binding sites has been performed by IR spectroscopy and, finally, polydopamine cytotoxicity has been studied in a cancer (BT474) and a healthy cell lines (NIHT3T3). As result, it has been found that this melanin analogous is toxic for both cell lines, possibly due to a ROS production process. So, in this manner, there would be a concern in the use of these metal-enriched polydopamine particles in some biomedical applications, but they could represent a potential antineoplastic agent [5].

References

[1] Hong L, Liu Y, Simon JD. Binding of metal ions to melanin and their effects on the aerobic reactivity. Photochemistry and Photobiology. 2004;80:477-81.

[2] Hong L, Simon JD. Current understanding on the binding sites, capacity, affinity and biological significance of metals in melanin. The Journal of Physical Chemistry B. 2007;111:7938-47.

[3] Lee H, Dellatore SM, Miller WM, Messersmith PB. Mussel-inspired surface chemistry for multifunctional coatings. Science. 2007;318:426-30.

[4] Cho S, Park W, Kim D-H. Silica-coated metal chelating-melanin nanoparticles as a dual-modal contrast enhancement imaging and therapeutic agent. ACS Applied Materials & Interfaces. 2017;9:101-11.

[5] Vega MA, Nieto C, Marcelo G, Martín del Valle EM. Cytotoxicity of paramagnetic cations-loaded polydopamine nanoparticles. Colloids and Surfaces B: Biointerfaces. 2018. doi: 10.1016/j.colsurfb.2018.04.027