Non-invasive continuous monitoring of pro-oxidant effects of engineered nanoparticles on aquatic microorganisms

Abstract

Engineered nanomaterials (ENMs) are key drivers for the development of highly sophisticated new technologies. As all new attainments, the rapidly increasing used of ENMs raise concerns about their safety for the environment and humans. There is growing evidence showing that if engineered nanomaterials are released into the environment, there is a possibility that they could cause harm to aquatic microorganisms. Among the divers effects triggering their toxicity the ability of ENMs to generate reactive oxygen species (ROS) capable of oxidizing biomolecules is currently considered a central mechanism of toxicity. Therefore, development of sensitive tools for quantification of the ROS generation and oxidative stress are highly sought. After briefly introducing ENMs-induced ROS generation and oxidative stress in the aquatic microorganisms (AMOs), this overview paper focuses on a new optical biosensor allowing sensitive and dynamic measurements of H2O2 in real-time using multiscattering enhanced absorption spectroscopy. Its principle is based on sensitive absorption measurements of the heme protein cytochrome c whose absorption spectrum alters with the oxidation state of constituent ferrous FeII and ferric FeIII. For biological applications cytochrome c was embedded in porous random media resulting in an extended optical path length through multiple scattering of light, which lowers the limit of detection to a few nM of H2O2. The sensor was also integrated in a microfluidic system containing micro-valves and sieves enabling more complex experimental conditions. To demonstrate its performance, abiotic absorption measurements of low concentrations of dye molecules and 10 nm gold particles were carried out achieving limits of detection in the low nM range. Other biologically relevant reactive oxygen species can be measured at sub-μM concentrations, which was shown for glucose and lactate through enzymatic reactions producing H2O2. In ecotoxicological investigations H2O2 excreted by aquatic microorganisms exposed to various stressors were measured. Pro-oxidant effects of nano-TiO2 and nano-CuO towards green alga Chlamydomonas reinhardtii were explored in various exposure media and under different light illuminations. Dynamics of Cd2+ induced effects on photosynthetic activity, sensitisation and recovery of cells of C. reinhardtii was also studied.

Effects of manufactured nanomaterials on algae: Implications and applications

“…Oxidative stress has been widely considered as one of the dominant mechanisms in the toxic effect of MNMs on algae (Xiao et al, 2016;Santschi et al, 2017;Chen et al, 2019). MNMs have unique physicochemical properties (e.g., photocatalytic, oxidative capability), which may trigger reactive oxygen species (ROS) formation in algal cells via direct and indirect chemical reactions (Ouabadi et al, 2013;von Moos and Slaveykova, 2014).…”

“…Generally, the intracellular ROS could be generated via directly contact-mediated approach, or indirectly through dissolved ions. The direct MNMs-mitochondria contacts could compromise the organelle membrane integrity, which would release of Ca 2+ ions from interior stores and further activate the ROS-generating Ca 2+ /calmodulindependent enzymes (Santschi et al, 2017). Additional direct pathways may associate with the interactions between MNMs and membrane-bound enzymes to trigger ROS formation (Navarro et al, 2008).…”

Self-Assembled Antimicrobial Nanomaterials

“…[ 77 ]. However, these NPs are nondegradable and persist in the aquatic environment affecting aquatic organisms such as prokaryotes, unicellular eukaryotes, and ciliates [ 77 , 80 , 81 ]; their steadily increasing use and release into the environment, especially into aquatic systems, inevitably raises the need of further research on the still unknown impact on aquatic ecosystems. In the mid-1990s, research on the toxicity of man-made, airborne nanoparticles towards pulmonary and other in vitro mammalian cell lines led to the conclusion that the ability of particles to generate reactive oxygen (ROS) and nitrogen radical species at or near their surface led to the oxidative stress in host cells as a central mechanism in their cytotoxicity [ 82 ].…”

Distribution and trophic transfer of engineered nanoparticles along aquatic food chains and related influencing factors: A review

“…当ENPs的尺寸在10 nm~5 μm时, 可通过内吞作用被 内化(图1, 过程④) [10,11] . 一些金属ENPs [12] 和具有切 割效应的碳材料 [13] 则可以通过细胞壁和细胞膜的损 伤进入到细胞(图1, 过程⑤)等. ENPs进入细胞后, 会 与细胞质基质、细胞器 [14,15] (如叶绿体、线粒体)以及 遗 传 物 质 ( 细 胞 核 或 者 拟 核 ) [16,17] 相 互 作 用 ( 图 1). ENPs一旦进入细胞或者细胞核, 就有可能造成胞液 泄漏, 破坏遗传物质 [9] , 对子代乃至所处食物链(网) 产生不可控的后果.…”