Toxicity and oxidative stress induced by semiconducting polymer dots in RAW264.7 mouse macrophages

Abstract

The rapid development and acceptance of PDots for biological applications depends on an in depth understanding of their cytotoxicity. In this paper, we performed a comprehensive study of PDot cytotoxicity at both the gross cell effect level (such as cell viability, proliferation and necrosis) and more subtle effects (such as redox stress) on RAW264.7 cells, a murine macrophage cell line with high relevance to in vivo nanoparticle disposition. The redox stress measurements assessed were inner mitochondrial membrane lipid peroxidation (nonyl-acridine orange, NAO), total thiol level (monobromobimane, MBB), and pyridine nucleotide redox status (NAD(P)H autofluorescence). Because of the extensive work already performed with QDots on nanotoxicity and also because of their comparable size, QDots were chosen as a comparison/reference nanoparticle for this study. The results showed that PDots exhibit cytotoxic effects to a much lesser degree than their inorganic analogue (QDots) and are much brighter, allowing for much lower concentrations to be used in various biological applications. In addition, at lower dose levels (2.5 nM to 10 nM) PDot treatment resulted in higher total thiol level than those found with QDots. At higher dose levels (20 nM to 40 nM) QDots caused significantly higher thiol levels in RAW264.7 cells, than was seen with PDots, suggesting that QDots elicit compensation to oxidative stress by upregulating GSH synthesis. At the higher concentrations of QDots, NAD(P)H levels showed an initial depletion, then repletion to a level that was greater than vehicle controls. PDots showed a similar trend but this was not statistically significant. Because PDots elicit less oxidative stress and cytotoxicity at low concentrations than QDots, and because they exhibit superior fluorescence at these low concentrations, PDots are predicted to have enhanced utility in biomedical applications.

Recent advances of semiconducting polymer nanoparticles in in vivo molecular imaging

“…A recent in vitro study conducted by Ye et al [56] evaluated the toxicity and oxidative stress induced by semiconducting polymer dots in RAW264.7 mouse macrophages. Using a series of assays evaluating cell viability (MTT and trypan blue), proliferation (propidium iodide based flow cytometry) and necrosis as well as fluorescence based assays to measure oxidative stress to the cells the authors demonstrate that toxicity is dose dependent and significantly lower as compared to equivalent doses of quantum dots.…”

Recent Advances in the Development of Highly Luminescent Semiconducting Polymer Dots and Nanoparticles for Biological Imaging and Medicine

“…13,18 We recently performed a systematic comparative study on the cytotoxicity of Pdots and Qdots, both at the gross cell level (e.g., cell viability, proliferation, and necrosis) and at a molecular level (e.g., redox stress). 20 These recent reviews, perspectives, and research articles suggest that Pdots are preferable for many biomedical applications. In this Review, we mainly will highlight recent advances of luminescent Pdots (including fluorescence, phosphorescence, and electro- and chemiluminescence) or CPNs that are comprised of more than 50% semiconducting polymer.…”

Single step synthesized sulfur and nitrogen doped carbon nanodots from whey protein: nanoprobes for longterm cell tracking crossing the barrier of photo-toxicity

“…15,16 However, the heavy metal originated quantum dots have been observed to cause generation of free radicals, resulting in cytotoxicity and developmental defects 17,18 . However, quantum dots were mostly synthesized out of toxic metals like cadmium, lead, indium and arsenic.…”