Synthesis and characterization of nanozeolite NaY and its potential as alternative adjuvant theraphy for cancer

Abstract

The efficacy of zeolite as anticancer adjuvant is unclear, but natural zeolite clinoptilolite has been proven to have antiproliferation activity against cancer cells. This research investigated the potential of synthetic nanozeolite as anticancer adjuvant in vitro. Initial study proved the antiproliferation abilities of zeolite NaY (Zeo-NaY), commercial zeolite Y (CBV300) and beta (CP814E) against six types of cancer cells through 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The aim of this research was to synthesize nanozeolite NaY (Nano-NaY) with higher antiproliferation activity and tolerance to gastrointestinal condition using organotemplate-free method and rice husk ash (RHA) as the silica source. The newly-synthesized Nano-NaY was characterized by X-ray diffraction (XRD), Fourier transform infra-red (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and surface area analysis. Structural stability of Nano-NaY was tested in simulated gastric fluid (SGF) and intestinal fluid (SIF) at different concentrations by monitoring its characteristic and elemental composition (Al3+, Si4+). Elemental composition (Ca2+, Mg2+) of nanozeolite-treated media were analyzed before and after preparation. Cytotoxicity of Nano-NaY was tested by MTT assay against colon cancer cells (HT-29) and normal liver cells (WRL-68). Pure Nano-NaY was successfully synthesized with the particles sized from 220 nm to 470 nm, and 788 m2/g surface area. Incubation of 30 mg/ml Nano-NaY in simulated gastrointestinal fluid (SGIF) resulted in slight dealumination of the Nano-NaY, but its structure remained stable. Reduction of Ca2+ and Mg2+ concentrations (35-85%) from nanozeolite-treated media suggested adsorption of the cations by Nano-NaY through ionic exchange mechanism. Antiproliferation activity and cytotoxicity of Nano-NaY were dependent on its micropore surface area (Smicropore), with initial half maximal inhibitory concentration (IC50) against HT-29 recorded at 1.26 mg/ml. The cytotoxicity against WRL-68 after incubation in SGIF was low (IC50 = 650 mg/ml). Thus, Nano-NaY might have the potential as an alternative adjuvant therapy for colorectal cancer.