Fancy-Shaped Gold–Platinum Nanocauliflowers for Improved Proton Irradiation Effect on Colon Cancer Cells

Abstract

Enhancing the effectiveness of colorectal cancer treatment is highly desirable. Radiation-based anticancer therapy—such as proton therapy (PT)—can be used to shrink tumors before subsequent surgical intervention; therefore, improving the effectiveness of this treatment is crucial. The addition of noble metal nanoparticles (NPs), acting as radiosensitizers, increases the PT therapeutic effect. Thus, in this paper, the effect of novel, gold–platinum nanocauliflowers (AuPt NCs) on PT efficiency is determined. For this purpose, crystalline, 66-nm fancy shaped, bimetallic AuPt NCs were synthesized using green chemistry method. Then, physicochemical characterization of the obtained AuPt NCs by transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy dispersive X-ray spectroscopy (EDS), and UV-Vis spectra measurements was carried out. Fully characterized AuPt NCs were placed into a cell culture of colon cancer cell lines (HCT116, SW480, and SW620) and a normal colon cell line (FHC) and subsequently subjected to proton irradiation with a total dose of 15 Gy. The 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) test, performed after 18-h incubation of the irradiated cell culture with AuPt NCs, showed a significant reduction in cancer cell viability compared to normal cells. Thus, the radio-enhancing features of AuPt NCs indicate their potential application for the improvement in effectiveness of anticancer proton therapy.

Radiosensitization Effect of Gold Nanoparticles in Proton Therapy

“…According to Lin et al, the AuNPs freely distributed in the cytoplasm can result in a higher dose enhancement than those aggregated inside the endosomes because of lower internal absorption of secondary electrons in the AuNPs ( 42 , 94 ).Provisional in silico results show that AuNP shell coatings lead to a decreased electron yield, which may not be beneficial to the improvement of RT in the presence of AuNPs ( 85 ). A recent in vitro study of Klebowski et al described the radiation enhancement effect of bimetallic gold-platinum nanocauliflowers, with a highly developed surface area and average size of 66 nm, for the treatment of colon cancer with PT ( 95 ). A clinical proton therapy system (IBA Proteus C-235 cyclotron) with a beam energy of 225 MeV was used for these experiments, which showed a significant reduction in cancer cell viability compared to normal cells.…”

Gold-Decorated Platinum and Palladium Nanoparticles as Modern Nanocomplexes to Improve the Effectiveness of Simulated Anticancer Proton Therapy

“…It is also worth noting that the simultaneous placing of both precursors in the reaction vessel at the same time, followed by their reduction with gallic acid, would result in obtaining bimetallic nanoparticles consisting of a gold core and a platinum/palladium shell. The gold precursor, due to the much higher redox potential, would be reduced faster than the other, as demonstrated in our previous study [ 20 ].…”

“…In turn, in the next step after the addition of chloroauric acid to the reaction mixture containing pre-synthesized Pt or Pd NPs, the rest of the reaction occurs rapidly, which results in an immediate color change of the solution. As demonstrated in previous work, this is due to the fact that there is a significant difference in the redox potentials of the platinum/palladium and gold precursors [ 20 , 31 ]. These differences in redox potential are the driving force behind this reaction and therefore, they take place quickly.…”

“…In our synthesis, it served as a reducing agent, as well as a stabilizer, preventing the agglomeration of NPs [ 28 ]. The undoubted advantage of gallic acid is not only its eco-friendliness, but also its low cost and a wide spectrum of activity, as a potential reducing agent of various noble metal precursors [ 20 , 29 , 30 , 31 , 32 ].…”

“…Noble metal nanoparticles, based on gold (Au NPs), platinum (Pt NPs), and palladium (Pd NPs), are characterized by highly developed surface, stability, good thermal properties, and the ability to generate reactive oxygen species (ROS) under the influence of applied radiation, which increases their biological effectiveness [ 12 , 13 , 14 , 15 ]. So far, the literature contains several papers on using in vitro Au, Pt, bismuth (Bi), gadolinium (Gd) NPs, as well as bimetallic nanocomplexes as potential radiosensitizers in PT [ 16 , 17 , 18 , 19 , 20 ]. The experimental studies correspond to a number of theoretical works using the Monte Carlo method to assess the improvement of PT by NPs [ 18 , 21 , 22 , 23 ].…”