Synthesis of water-dispersible zinc oxide quantum dots with antibacterial activity and low cytotoxicity for cell labeling

Abstract

Typical photoluminescent semiconductor nanoparticles, called quantum dots (QDs), have potential applications in biological labeling. When used to label stem cells, QDs may impair the differentiation capacity of the stem cells. In this study, we synthesized zinc oxide (ZnO) QDs in methanol with an average size of ∼2 nm. We then employed two different types of polyethylene glycol (PEG) molecules (SH-PEG-NH2 and NH2-PEG-NH2) to conjugate ZnO QDs and made them water-dispersible. Fourier transform infrared spectroscopy spectra indicated the attachment of PEG molecules on ZnO QDs. No obvious size alteration was observed for ZnO QDs after PEG conjugation. The water-dispersible ZnO QDs still retained the antibacterial activity and fluorescence intensity. The cytotoxicity evaluation revealed that ZnO QDs at higher concentrations decreased cell viability but were generally safe at 30 ppm or below. Cell lines of hepatocytes (HepG2), osteoblasts (MC3T3-E1) and mesenchymal stem cells (MSCs) were successfully labeled by the water-dispersible ZnO QDs at 30 ppm. The ZnO QD-labeled MSCs maintained their stemness and differentiation capacity. Therefore, we conclude that the water-dispersible ZnO QDs developed in this study have antibacterial activity, low cytotoxicity, and proper labeling efficiency, and can be used to label a variety of cells including stem cells.

Application of new ZnO nanoformulation and Ag/Fe/ZnO nanocomposites as water-based nanofluids to considerin vitrocytotoxic effects against MCF-7 breast cancer cells

“…Zinc oxide quantum dots (QDs) with special and strong band gap energy (a mobile charge carrier) as typical photoluminescent (PL) semiconductor NPs have demonstrated antibacterial and anticancer effects. ZnO QDs can be synthesized in liquid media such as alcohol and become water dispersible by conjugation via functionalized groups such as fatty acids, PEG molecules, organosilanes, and polymers (Hsu et al 2013). Previously, our investigations suggested that various ZnO QDs and NPs with modified morphologies have a great antibiotic activity against many dangerous Gram-negative and -positive bacteria (Fakhroueian et al 2013).…”

Preparation of poly(N-vinylpyrrolidone)-stabilized ZnO colloid nanoparticles

“…Among different processing methods, the sol–gel technique has various advantages such as cost-efficient processing, low-temperature sintering capability, the possibility of coating large and complex surfaces, and the capability to produce high quality coatings with a wide range of easily controlled thicknesses [5]. Preparation of ZnO nanoparticles by a colloidal method in the form of hydrosols was widely investigated in recent years in connection with a possible employment in biology [6]. ZnO nanoparticles have been synthesized in conjunction with different polymers such as polyethylene glycol (PEG) and poly( N -vinylpyrrolidone) (PVP).…”

Safety issue of nanoparticles which used for stem cell labeling and tracking

“…Although QDs have been utilised for stem cell tracking and imaging for many years [51][52][53][54][55][56][57][58], most toxicity and pharmacokinetic studies have focused on the behaviours of II B-VI A and III A-V A QDs in rodents [59]. Investigations of the IV A QDs are still in the early stages.…”