Nano EHS Impact Globally: Predictive Approach Assists nano EHS Decision Making and Risk Identification

Transcription

1 Nano EHS Impact Globally: Predictive Approach Assists nano EHS Decision Making and Risk Identification Nanomaterial libraries High throughput screening In silico decisions, in vitro ranking Compositional Me Oxides Metals CNTs Similar behavior (Cluster) Property accentuation Size, Shape, AR Dissolution Band gap Risk Identification and decision making to Reduce risk Influence governance Dosimetry calculations Safer design Pulmonary inflammation Cells, bacteria, yeasts, zebra fish embryos High toxicity Moderate Low toxicity (nuisance dust) Dose (mass, surface area dose, reactive surface area) In vivo hazard ranking Prioritize Speed up Dosimetry Validate Exposure Dosimetry Organism Animal testing

2 Assembly and characterization of an Engineered Nanomaterial Library >30 types of compositions Metal oxides: 25 (TiO 2, ZnO, CeO 2, CuO ) Doped metal oxides: 3 (Fe-ZnO, Fe-TiO 2, Al-ZnO) Metals: 3 (Ag, Pt, Pd) Carbon nanotubes: 2 (SWNT, MWNT) Origin Commercial Sol-gel method Hydrothermal technique Flame spray pyrolysis Hydrothermal Flame Spray Pyrolysis d=10 nm Cube 50 nm d=30 nm Rod d=130 nm Wire Various sizes, shapes, and crystal structures >40 different sizes, typically 5 to 200 nm Shapes: spherical, cubic, rod, wire, tube Crystallinity: amorphous, mesoporous, crystalline TOTAL OF 149 TYPES OF NANOPARTICLES IN THE LIBRARY Godwin et al. EST Thomas et al. ACS Nano. 2011

3 Efficient separation, purification and dispersion of SWNCT for toxicity studies Three manufactures, differently catalytically synthesized Separated using ultracentrifugation Highly dispersed using Pluronic tri-block copolymer F108 Suitable for cellular or organismal study of individual nanotubes SWNT in PBS Pluronic 1h sonication As-prepared SWNT w/ Pluronic in PBS After sonication Purified F108-dipsersed two years Ultracentrifugation (41,000 rpm) ENM-2: Mark Hersam, Matthew C. Duch SWCNT w/ Pluronic in PBS After two years Wang et al. ACS Nano. 2011

4 Safer design principle for nano-zno by using iron doping Mädler & Pokhrel: Theme 1 ZnO Metal Ions Iron doping decreases ZnO dissolution 24 BAL PMN count (x10 4 ) C57BL/6 * * George et. al. ACS Nano Xia et al. ACS Nano

5 Zebrafish HTS hazard ranking on 24 MOx s Ctrl Automated machine-learning based on phenotype Theme Liu et al. PLOS One % hatching * * * * 24

6 NP stability and mobility in suspension is strong function of aqueous chemistry Nanoparticle Freshwater Groundwater Seawater TiO 2 CeO 2 ZnO CeO 2 CuO Ag citrate Ag PVP Pt Pd Fe (0) - coated Most Me & MOx NPs are stable in freshwater due to NOM Lower stability in groundwater due to high Ca 2+ Most NPs are unstable in seawater due to high ionic strength Longer polymeric coating (e.g. PVP) increase stability Deposition of unstable solutions occurs in min to hr Stability is a strong function of surface charge, which is a function of [NOM], ph, and ionic strength Keller et al. ES&T. 2010; Thio et al. ES&T. 2011; Thio et al. J HazMat Suspensions are considered stable when the particle concentration remains constant 1

7 Attachment to mineral surfaces depends on [NOM] and coatings Nanoparticle Freshwater Groundwater Seawater TiO 2 Coated Ag Fe 2 O 3 ZnO CeO 2 CuO TBD TBD Ag citrate Ag PVP Pt TBD TBD Pd TBD TBD Fe (0) - coated TBD TBD Higher attachment in groundwater (includes filtration and straining) Lower attachment in seawater due to higher [NOM] Lowest in freshwater due to high [NOM] For coated NPs significantly reduced attachment observed Thio et al. ES&T. 2011; Thio et al. J HazMat. 2011; Thio et al. Langmuir Coated Ag 1

8 Decrease Soil DNA Nano-TiO 2 & -ZnO Impacts on Soil Microbial Communities Change specific taxa abundance Change Bacterial Community Axis to 2 mg/g nano-tio 2 Rhizobiales (%) Y = -1.48X R 2 = 0.50 P = Y = -2.22X R 2 = 0.55 P = Bradyrhizobiaceae (%) Y = -0.97X R 2 = 0.60 P = Y = -1.40X R 2 = 0.62 P = control Axis 1 TiO 2 (mg g -1 ) TiO 2 (mg g -1 ) Incl.: N 2 fixation, Fe cycling, CH 4 oxidation Ge et al. ES&T Ge et al. Submitted Environmental Taxa for Theme 2 HTS

9 Soybean Cultivated in soil w/ Nano- ZnO or CeO 2 Zn in leaves mg Zn/kg dry weight control low medium high Priester et al. Submitted N 2 -Fixation Potential Rate 4.5E E E E E E E E E E+00 N 2 fixation by nodules containing Ce Control Ce Low Ce Med Ce High

10 Hypothesis: TiO 2 ENMs are toxic to phytoplankton under natural light levels due to photo-activated production of ROS Population Population growth growth hr -1 hr - 1 Thallassiosira pseudonana TiO 2 was toxic under natural light levels Mechanism of titania toxicity was production of ROS TiO 2 mg L -1 (ppm) CuO and Ag significantly reduced population growth rates CeO 2 and SWCNTs had no effects Miller et al. PLOS

11 Hypothesis: ZnO disrupts membrane function, produces ROS leading to cell death, which leads to reduced population growth Mitochondrial membrane potential Isochrysis galbana Membrane permeability (Cell death ) RF Relative fluorescence (RF) ZnO mg L -1 (ppm) Reactive oxygen species (ROS) production Population growth hr -1 ZnO mg L -1 (ppm) ZnO mg L -1 (ppm) ZnO mg L -1 (ppm) Miller et al. ES& T. 2012

12 A Mechanistic Computational Transport Model of Nanoparticles Agglomeration Predict the size distribution (SD) of nanoparticles in aqueous suspensions (particle-particle interactions, sedimentation, diffusion) Validated with CEIN & literature reported data for TiO 2, CeO 2, and C60 (IS= mm, ph=3 10.4) Modeling approach can be extended to account for non-dlvo interactions and complex geometries Liu et al. ES&T. 2011

13 Developed Computational Algorithms and Tools for Knowledge Extraction from HTS Toxicity Data Robust statistical analyses, machine learning methods & tools for mining the CEIN data sets of enms toxicity (cell lines and whole organisms) HTS Data processing algorithms and web-based tools for rapid HTS data exploration including hit identification, clustering, and visualization - Self-organizing maps (SOM) representation of HTS toxicity data - SOM clustering for similarity analysis of toxicity-associated cell signaling pathways Rallo et al. ES&T Hit identification in HTS data - QSARs based on processed HTS data Cloud-based HTS data analysis system

14 ENM Industry EHS and Risk Perception: Need for Information & Regulation 100% 90% Percent of companies 80% 70% 60% 50% 40% 30% 20% 10% Phone & web survey of 78 companies in 14 countries 0% Carbon nanotubes Heavy metals Dry powders Quantum dots Other carbonaceous materials Moderate - high risk Don't know Almost no risk - slight risk Metal Oxides Large majority of industry leaders are uncertain or show moderate/high perceived risk re: ENMs, combined don t know plus moderate/high risk = 64%(metal oxides) - 83% (quantum dots) yet not self protective and prefer autonomy from regulation Engeman et al. JNR. 2012

15 Training Future Researchers and Broadening Participation Through Nanoecotoxicology Online Course Available online to external partners Topics based on UC CEIN research and include: Overview of Field Nanoscience Basics Toxicology Basics Characterization of NMs Nanoecotoxicology Methods (Cellular, Organismal, Population Level) HTS and HCS for Nanoecotox Risk Perception and Societal Implications Nanoregulatory Policy 1 mg ml -1 Sonication 15 min Sonication 15 min Stock Solution BSA NPs 50 µg ml -1 Dilute Final Suspension Suspension Medium DLS

16 Development of Standard Research Protocols Based on UC CEIN Science Publically Available Protocols: UC_CEIN_research_Protocols.html) Dispersion & Fate/Transport Protocols: Aqueous dispersion of MO x NPs HT DLS of NPs in cell culture media Measurement of aggregation kinetics for MO x NPs Dispersion of MWCNTs in cell culture media using DPPC Introduction of MO x NPs into soil for ecotox studies Cellular Assays: HTS of nanotoxicity using a multiparametric assay Oxidative stress assay for MO x NPs in mammalian cells Organismal Assays: Toxicity Screening for NPs in Zebrafish embryos