MgO Nanoparticles Obtained from an Innovative and Sustainable Route and Their Applications in Cancer Therapy

Abstract

This paper aimed to evaluate the biological damages towards diseased cells caused by the use of MgO nanoparticles (NPs). The NPs are produced by a calcination process of a precursor, which is an aqueous suspension of nanostructured Mg(OH)₂, in turn synthesized following our original, time-energy saving and scalable method able to guarantee short times, high yield of production (up to almost 10 kg/week of NPs), low environmental impact and low energy demand. The MgO NPs, in the form of dry powders, are organized as a network of intercrystallite channels, in turn constituted by monodispersed and roughly spherical NPs < 10 nm, preserving the original pseudo hexagonal-platelet morphology of the precursor. The produced MgO powders are diluted in a PBS solution to obtain different MgO suspension concentrations that are subsequently put in contact, for 3 days, with melanoma and healthy cells. The viable count, made at 24, 48 and 72 h from the beginning of the test, reveals a good cytotoxic activity of the NPs, already at low MgO concentrations. This is particularly marked after 72 h, showing a clear reduction in cellular proliferation in a MgO-concentration-dependent manner. Finally, the results obtained on human skin fibroblasts revealed that the use MgO NPs did not alter at all both the vitality and proliferation of healthy cells.

Keywords: HRTEM; MgO against cancer growth; MgO nanoparticles; XRD; growth curves of melanoma cells; ion exchange process; scalable and time-energy synthesis; therapeutic applications.

Figure 1

X-ray diffraction pattern of the synthesized nanoparticles. (a) The precursor Mg(OH)₂ (MH sample); (b) MgO NPs obtained after the calcination process (MgO sample).

Figure 2

HRTEM images of MH nanoparticles acting as a precursor. (a,b) The presence of pseudo-hexagonal lamellas much lower than 90 nm with thicknesses less than 10 nm can be observed; (c) at higher magnification, each lamella was really composed by a self-assembly of primary and homogeneously dispersed nanoparticles < 10 nm.

Figure 3

TEM images of the produced MgO NPs obtained starting from the calcination process of the precursor. (a,b) Following the pseudomorphic decomposition of MH, the formation of a network of intercrystallite channels of MgO NPs can be observed; (c) each pseudo-hexagonal lamella is composed by an aggregation of monodispersed and roughly spherical MgO NPs, less than 10 nm.

Figure 4

(a) Nitrogen adsorption–desorption isotherms for MH dry powders; (b) Barrett–Joyner–Halenda (BJH) pore size distribution curve determined by using the N₂ desorption isotherm.

Figure 5

(a) Nitrogen adsorption–desorption isotherms for MgO dry powders; (b) Barrett–Joyner–Halenda (BJH) pore size distribution curve determined by using the N₂ desorption isotherm.

Figure 6

(a,c) Histograms representing the number of live melanoma and healthy cells in relation to the MgO suspension concentration as well as to the incubation time; (b,d) growth curves of melanoma cells and skin fibroblasts expressed as a function of the incubation time and the MgO suspension concentration too.