Sodium hexametaphosphate\u2013induced enhancement of silver nanoparticle toxicity towards leukemia cells

Magdalena Oćwieja,Anna Barbasz

doi:10.1007/s11051-020-04903-w

Abstract

Synergistic effects occurring between biologically active substances are of great importance for efficient treatment of many diseases. Therefore, the aim of research was to determine impact of sodium hexametaphosphate (HEX), which is a well-known permeabilizer, on the cytotoxicity of silver ions and two types of AgNPs towards HL-60 and U-937 tumor cells. The AgNPs were synthesized in a chemical reduction method using sodium borohydride and trisodium citrate (CITAgNPS) or sodium hypophosphite and HEX (HEXAgNPs). Imaging with the use of transmission electron microscopy (TEM) and atomic force microscopy (AFM) revealed that the AgNPs exhibited spherical shape and comparable size distribution. Electrophoretic mobility studies showed that the AgNPs were negatively charged. The mitochondrial and antioxidant activity as well as membrane lipid peroxidation and integrity after dose-dependent AgNP treatment were evaluated using biochemical assays. The impact of HEXAgNPs on the membrane integrity and inactivation of antioxidant enzymes of the cells was much higher than this one observed for CITAgNPs and silver ions of the same concentration. The membrane damage occurred as a result of lipid peroxidation which was induced by pure HEX and HEXAgNPs. It was also observed that HEX significantly increased cell membrane damage induced by CITAgNPs and silver ions although the cells exhibited different sensitivity to these components. Moreover, it was found that HEX can induce oxidative stress. Hence, it was revealed that HEX enhances AgNP activity when it is applied both as their stabilizer or supplement in their suspensions.

Highlights

Numerous literature reports describing research with living organisms have indicated that biological activity of silver nanoparticles (AgNPs) strongly depends on their size (Carlson et al 2008; Lu et al 2013), morphology (Pal et al 2007), and surface properties including surface charge
It is worth mentioning that in the previous literature reports describing the preparation of AgNPs (Li et al 2010; Liu et al 2010) or AuNPs capped by HEX, the polyvinyl pyrrolidone (PVP) was used to improve the stability of the nanoparticles
CITAgNPs were prepared according to the wellknown method relies on a reduction of silver ions in the medium containing sodium borohydride and trisodium citrate (Barbasz et al 2017)

Summary

Introduction

Based on the results of experimental studies, it was documented that some positively charged AgNPs are more toxic towards numerous pathogens and cancer cells than negatively charged nanoparticles (Abbaszadegan et al 2015; Suresh et al 2012). This effect was mainly explained by the attractive electrostatic interactions which occur between AgNPs and negatively charged cell membranes. The surface charge of AgNPs is mainly tuned by molecules of stabilizing agents adsorbed on their surface (Abbaszadegan et al 2015; Le Ouay and Stellacci 2015). The presence of these molecules plays a pivotal role in the bioactivity of AgNPs (Pokhrel et al 2013)

Methods

Results

Discussion

Conclusion