Gold and Silver Nanoparticles Biomimetically Synthesized Using Date Palm Pollen Extract-Induce Apoptosis and Regulate p53 and Bcl-2 Expression in Human Breast Adenocarcinoma Cells

Abstract

Recently, several attempts have been made to use the phytopharmaceuticals from plant extracts as reducing, capping and stabilizing agents for the biomimetic synthesis of various metal nanoparticles conjugated to the phytopharmaceuticals. These biogenic metal nanoparticles are non-toxic and can be used as contrast agents, drug delivery vehicles and photothermal agents for cancer therapy. Herein, we report the synthesis of both silver and gold nanoparticles using the pollen extract of Phoenix dactylifera (Date Palm), characterization using UV-visible spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy, quantitation of phytochemicals capping the nanoparticles using Folin - Ciocalteu's method, cytotoxicity studies on MCF-7 breast cancer cells, cancer cell death analysis using fluorescent microscopy, and modulation of expression of the pro-apoptotic p53 and anti-apoptotic Bcl-2 proteins. The biosynthesis resulted in stable and poly-dispersed silver nanoparticles and gold nanoparticles, exhibiting strong and broad surface plasmon absorption peaks. The elemental analysis confirmed the presence of gold and silver of high purity and also the organic moieties from the plant extract acting as capping and stabilizing agents. The biogenic nanoparticles also exhibited dose-dependent cytotoxicity on MCF-7 cells and showed signs of apoptotic cell death. Immunoassays revealed the upregulation of the pro-apoptotic protein p53 and down-regulation of the anti-apoptotic protein Bcl-2 after the nanoparticle treatment.

Keywords: Apoptosis; Breast cancer; Cytotoxicity; Nanoparticles; Phoenix dactylifera; Phytochemicals.