ERIK HUUSFELDT LARSEN, PH.D. LEADER OF NANO-BIOSCIENCE NATIONAL FOOD INSTITUTE TECHNICAL UNIVERSITY OF DENMARK

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1 Nanoparticles in food and beyond. Analytical methods and omics for study of their occurrence and potential health effects. ERIK HUUSFELDT LARSEN, PH.D. LEADER OF NANO-BIOSCIENCE NATIONAL FOOD INSTITUTE TECHNICAL UNIVERSITY OF DENMARK

2 Nanoparticles Particles having one or more dimensions in the size range of 1 to 100 nm. One nanometer (nm) is a billionth of a meter 10 7 x 10 7 x

3 Nanoparticles in our daily lives? Carbon atom Gold atom Diameter (nm) 0.1 Particles with sizes between about 1 and 100 nm (at least in one dimension) 1 Engineered nanoparticles Albumin Diesel exhaust 10 fullerene carbon nanotube Clay Asbestos 100 Virus gold nanoparticles 1000

4 Nanoparticles in food: benefits vs. safety TEXTURE ANTIMICROBIAL PACKAGING Degradable foils made with nano particles that limit bacteria. Food spreadability and stability improve with nano-sized crystals and lipids for better low-fat NEW UNKNOWN TOXIC EFFECTS BECAUSE OF THE SMALL SIZE ENHANCED NUTRIENT DELIVERY Nano-encapsulating improves bioavailability of vitamins, antioxidants, PUFs and other nutraceuticals. UNKNOWN RISKS FOR THE CONSUMER HEALTH UNKNOWN RISKS FOR THE ENVIRONMENT

5 Q: Why are properties of nanosized particles different from corresponding bulk material? A: High proportion of non-coordinated surface atoms Catalytic activity Redox activity (ROS formation) Refs.: Grainger and Castner, 2008 Oberdörster et al, 2007

6 Types of nanomaterial mentioned in 633 records of the Nano Inventory Ref.: RIKILT and JRC, Inventory of Nanotechnology applications in the agricultural, feed and food sector. EFSA supporting publication 2014:EN-621, 125 pp.

7 Nanomaterials in agriculture, feed and food applications Ref.: RIKILT and JRC, Inventory of Nanotechnology applications in the agricultural, feed and food sector. EFSA supporting publication 2014:EN-621, 125 pp.

8 Challenges when working with nanoparticles in food and biological matrices Energy input primary particles Dissolution speciation Agglomeration (reversible) Aggregation (irreversible) NP core (Bio)molecular corona particle-surface interaction (adsorption, repulsion)

9 Dispersion methods (1) Standardization of the power delivered by probe sonication Probe sonicator calibration by calorimetry* Temperature ( C) Tip amplitude (µm): linear fit : :01 00:02 00:03 00:04 00:05 Time (min) Input power (W) Set tip amplitude (in % or µm) Delivered power (W) Linear fit a = 0 ± 0 b = ± Tip amplitude (µm) *Taurozzi et al Nanotoxicology 5:

10 Metrics for nano-particle characterisation 10 in relation to safety assessment Variable Size distribution (by mass) Shape Composition Physico-chemical structure Agglomeration state Size distribution (by number) Surface area Surface chemistry Surface contamination Porosity Surface charge in suspension Surface charge -powder Crystal structure Importance Method of analysis Essential Essential Essential Essential Essential Essential Valuable Valuable Valuable Valuable AFFF-LS- ICP-MS Single particle ICP- MS, or TEM Valuable, but non-essential Valuable, but non-essential Valuable, but non-essential

11 AFFF-MALS/DLS-ICP-MS platform for characterisation of nanoparticles in liquid suspension Ba 90 Zr 140 Ce Asymmetric flow field flow fractionation (AF 4 ) Optical detection (multi angle and dynamic light scattering, UV and fluorescence) m/z Inductively coupled plasma mass spectrometry (ICP-MS) Particle separation according to their size (small NPs elute first) Diffusion force vs. cross flow Particle detection (fractogram) Size determination (root mean square, hydrodynamic and geometric radius) Elemental detection for identification of particles Quantification

12 Inlet Injection AFFF 12 Cell 25 cm Principle of asymmetrical flow FFF t r = 2 t0 w V& 6 D V 0 x Outlet 0.25 mm kda membrane Cross flow brings LMW material to waste Adapted from Wyatt Europe

13 Determination of Ag NP size distribution Fraction collection for transmission electron microscopy (TEM) nm 43 nm 60 nm Diameter determined by size-calibration curve (polystyrene standard spheres) DTU Food, Technical University of Denmark Loeschner et. al, J. Chrom. A (2012)

14 AF 4 -ICP-MS of AgNPs in enzymatically digested chicken meat vs. pristine AgNPs Proteinase K 1:5 40 min@37 o C (60 µg enzyme/mg tissue) 10 AgNPs diluted with ultrapure water enzymatically digested meat with AgNPs Significant nanofraction (~80%) recovered Ag mass concentration (ng/ml) void peak extra peaks 1 & 2 nanoparticle peak Formation of additional peaks red curve (0-5 min) Pre-elution (~ 2 min) in comparison to pristine AgNPs: Sizing by t R problematic Q: Does AgNP peak in fractogram reflect dissolution (i.e. smaller size) or non-ideal fractionation behavior? t 0 retention time (min) Loeschner, et al., Anal., Bioanal. Chem. (2013), 405,

15 Are silver NPs toxic in an animal model? 28 days dosage via sonde in GI tract of: AgNPs (14 nm o.d.), or AgAc (dissolved silver; Ag + ) Distribution in organs Determination of Ag by ICPMS in tissue following ashing with HNO 3 /HCl Distribution within organs Silver staining (as in photography) of tissue slices followed by light microscopy Is silver still in particle form? Distribution within cells? Have the particles agglomerated? Imaging by TEM/EDX of thin tissue slices ( nm).

16 Toxicity of ENPs to cells by ROS-formation 16 Reactive oxygen species (ROS):. O 2 - Superoxide H 2 O 2 Hydrogen peroxide. OH Hydroxy radical ROOH (lipid-)peroxide Oxidative stress = Too much ROS Ref.: Oberdörster et al (2007), Nanotoxicology, 1, 2-25

17 Stabilised silver nanoparticles analysed by batch-mode DLS 14 nm 50 nm AgNP + PVP Dynamic light scattering (DLS) and transmission electron microscopy (TEM) Approx. 10 % of Ag as Ag + or clusters (12,5 kda filter) Long-term stable (150 d)

18 Organ distribution of silver silver nanoparticles vs. silver acetate concentration of Ag (ng/g wet weight) Ag nanoparticles Ag acetate

19 Organ distribution of silver silver nanoparticles vs. silver acetate concentration of Ag (ng/g wet weight) Ag nanoparticles Ag acetate

20 Organ distribution of silver silver nanoparticles vs. silver acetate concentration of Ag (ng/g wet weight) Ag nanoparticles * * 12.6 mg/kg bw/day Ag acetate 9.2 mg/kg bw/day * * * *p < 0.05 Ag nanoparticles Ag acetate

21 Transmission electron microscopy (TEM) Silver nanoparticle exposed rat: ileum intestinal villus lysosome containing particles macrophage

22 Transmission electron microscopy (TEM) Silver acetate exposed rat: ileum lysosome containing particles particles in the basal lamina

23 Transmission electron microscopy (TEM) Silver nanoparticle exposed rat: ileum intestinal villus particles in the basal lamina

24 What can we learn about the chemical composition of AgNPs inside rat s intestinal cells? particles bacground particles background Energi (kev) Energi (kev) TEM+ energy dispersive X-ray spectroscopy (EDX)

25 Are silver NPs more harmful to rats than dissolved silver? Bodymass increase decrease Relative mass of thymus Control AgNPs (9 mg Ag/kg bw/day) AgAc (9 mg Ag/kg bw/day) Plasma alkaline phosphatase Plasma urea NOAEL: AgNPs: = 9 mg Ag/kg bw/day AgAc: < 9 mg Ag/kg bw/day NH3 Reference: N. Hadrup et al, accepteret til: Archives of Toxicology september 2011

26 Folie 25 NH3 Arch Toxicol Apr;86(4): Niels Hadrup;

27 Urine metabolome of rats following AgNP dosage: Female rats group separately from their controls and from males Female vehicle Female high NP Male vehicle Male high NP Females, 9 mg/kg b.w. as AgNPs

28 Urine metabolome of rats: Female rats group separately from their controls, but not by dosage level nor by AgNPs vs. AgAc PC 2 Female vehicle Female low NP Female mid NP Female high NP Female Ag-acetate PC1

29 NH4 Metabolomics by LC-Q-TOF-MS: Excretion of uric acid and allantoin were enhanced in female rats urine Uric acid (% control) 100 * *** Allantoin (% control) 100 ** ** *** *** Control Ag-NP low Ag-NP mid Ag-NP high Ag-acetate high Control Ag-NP low Ag-NP mid Ag-NP high Ag-acetate high Biochemical interpretation: Uric acid and allantoin may be increased due to ROS formation caused by exposure to AgNPs and AgAc Reference: N. Hadrup et al, Journal of applied toxicology in press

30 Folie 28 NH4 Erik bemærk at med en mere konservativ statistik foreslået af revieweren så er AgAc ikke signifikant for Uric Acid Niels Hadrup;

31 Summary.. A large and varied box of tools, and multidiciplinary collaboration, were necessary in nanotoxicology studies AgNPs or AgAc were distributed equally in the rat Silver, irrespective of the dosage form, exists as nanoparticles (Ag 2 S and/or Ag 2 Se) in intestinal cells Our research indicated that the AgNPs are (partially) dissolved and re-deposit as NPs in the cells Toxicological experiments with rats indicated, that AgNPs were equally or less toxic than AgAc for the investigated end-points 1000 $-question: Is it safe to recommend future use of AgNPs in contact with food?

32 What s next in food nanoscience? Scientific advancements Reference materials Advanced instrumentation Standardised dispersion methods of dry nanomaterials Sample preparation schemes EU legislation and new nanodefinition

33 EU legislation and regulation? Food to be labelled with nano from 13/ The essentials about food labelling with nano : 1. Engineered nanomaterial is intentionally produced and has one or more dimensions below 100 nm 2. The regulation foresees adaptation of the definition in accordance with technical/scientific progress (cf. suggested number based size distribution) 3. Ingredients as engineered nanomaterials shall be labelled with nano

34 COMMISSION RECOMMENDATION of 18 October 2011 New definition of nanomaterial based on number size distribution Number-based size 100% distribution of AgNPs By: spicpms or EM-methods

35 Conclusions The overview demonstrates: Physical interferences by matrix constituents remain a challenge, and case-to-case adaptations of sample preparation are necessary Even lower LODs for nanoparticle size is needed NanoDefine and other EU projects will assist the EU Commission in etablishing and controlling new definition Silver nanoparticles exist inside rodents tissues, possibly after dissolution and redeposition as sulfide and selenide salts

36 Technical University of Denmark, National Food Institute (DTU-Food), Nano-BioScience Group

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38 Characterisation of selenium nanoparticles stabilized with BSA size determination methods 2000 Fractogram 25 Size distribution TEM Image ICP-MS signal (cps) 90 LS signal free BSA retention time (min) AFFF-MALS-ICP-MS *RMS (nm) RMS - root mean square radius volume (%) hydrodynamic diameter (nm) Dynamic light scattering 20nm 50 nm Transmission electron microscopy

39 Resumé A large and varied box of tools and multidiciplinary collaboration is necessary in nanotox studies AgNPs or AgAc are distributed equally in the rat Silver, irrespective of the dosage form, exists as nanoparticles in intestinal cells Our research indicates that the AgNPs are (partially) dissolved and re-deposit as NPs in the cells Toxicological experiments with rats indicate, that AgNPs are equally or less toxic than AgAc for the investigated end-points 1000 $-question: Is it safe to recommend the use of AgNPs in contact with food?

40 Reference materials Neat AgNP suspension AgNPs in chicken meat Conclusions: Feasible? Yes Partial dissolution of AgNPs More methods and measurements needed for full certification

41 Advanced instrumentation Analysis of TiO 2 as Ti via Ti(NH 3 ) x clusters using triple quad technology Agilent technologies 8800 Q1 Cell Q2 Detector 9800 cps/ppb 10 ng/ml Ti ion sol. Q1: m/z 46-50; Q3: m/z ; Cell gas: 10% NH 3 in ca. 2 ml/min

42 spicp-qqq-ms of TiO 2 Enzymatic digestion in mouse liver Pristine TiO 2 NPs in water Mouse liver IT admin. Mouse liver IV admin. BED 53 nm Discussion: New software provides easy data analysis, and results were: Same background equivalent diameter (BED) in pristine and biological samples because of low background at m/z 150 (1-5 counts/dwell) No knowledge about NPs smaller than BED value Some agglomeration of TiO 2 NPs in biological tissue rel. to pristine

43 spicp-ms analysis of fractions collected after AF 4 separation Thermo Fischer icap Q 3 ms/60 kdwells Loeschner, et al., Anal., Bioanal. Chem. (2013), 405,

44 A B Optimised spicp-ms analysis of NIST RM 8013: C A. Dwell time (3-10 ms) B. AuNP concentration ( ng/l) C. Selection of threshold Loeschner et al., Anal., Bioanal. Chem. (2013) (DOI) /s y

45 Size and concentration of AuNPs in rat tissue determined by spicpms after TMAH or enzymatic treatment Number-based size distribution, o.d. (nm) Quantitative results (ng Au/g) Animal Alkaline Enzymatic Aqua regia (spicpms) (spicpms) (ICPMS) Mean RSD (%) Repeatability RSD (%) Both sample preparation methods give same AuNP size distribution Alkaline sample preparation gives more accurate quantitative results Ref.: Loeschner, K., Brabrand, M., Sloth, J.J., and Larsen, E.H., Anal., Bioanal. Chem. (2013) (DOI) /s y

46 Alkaline sample preparation in summary: The high content of solubilised organic matter impaired AF 4 separation of Ag and Au NPs, but not their ICP-MS detection The solubilised organic matter hampered optical detection methods: UV, MALS or DLS, precluding direct sizing information The effective tissue solubilisation was however, succesful for ICP-MS detection in single particle mode

47 Determination of silver nanoparticle size 1.0 ml/min cross flow Calibration with size standards (polymer nanoparticles) MALS not possible for sizing 44nm because Ag is an absorbing Nanoparticle and DLS is insensitive 59nm Löschner et al., J. Chrom. A (In press)

48 The icapq for spicp-ms Nano-relevant features: Dwell time 0,2-10 ms Large data buffer allowing 20 mins 3 ms dwell time High sensitivity e.g cps for 1 ng/ml Au Low instrumental background <1 m/z 220 Source: Thermo Fischer Scientific

49 Preparation of chicken meat prior to characterisation of Ag-NPs NPs in a liquid or tissue matrix Dilution of the matrix Degradation of the matrix Separation of NPs and matrix enzymatic chemical thermal chemical (NP-selective chemistry) physical Alkaline solubilisation AF 4 - Fractionation Acidic Wet ashing filtration centrifugation

50 Single particle-icpms, the principle

51 The icapq for spicp-ms Nano-relevant features: Dwell time 0,2-10 ms Large data buffer allowing 20 mins 3 ms dwell time High sensitivity e.g cps for 1 ng/ml Au Low instrumental background <1 m/z 220 Source: Thermo Fischer Scientific

52 Particle events during short dwell times in ICP-MS Multiple Single Partial Partial events event event x % event 100-x % 3 ms 6 ms 9 ms 12 ms Dwells Duration of an ion plume dwells is us

53 Time scan of Ag NPs in water. 50 ng/l; 3 ms dwell; cps at m/z 107 (silver) Time scan Signal hgt(cps) Time (ms) Each signal is calibrated by an external standard curve to get mass, which is converted to size by assumption of spherical shape of nanoparticle

54 AF 4 - ICP-MS of AgNPs in enzymatically digested chicken meat vs. pristine AgNPs 10 AgNPs diluted with ultrapure water enzymatically digested meat with AgNPs Significant nanofraction (~80%) recovered Ag mass concentration (ng/ml) void peak extra peaks 1 & 2 nanoparticle peak Formation of additional peaks red curve (0-5 min) Pre-elution (~ 2 min) in comparison to pristine AgNPs: Sizing by t R problematic Q: Does AgNP peak in fractogram reflect dissolution or non-ideal fractionation behavior of AgNPs? t 0 retention time (min) Loeschner, et al., Anal., Bioanal. Chem. (2013), 405,

55 Summary.spICPMS Pros Easy and fast analysis with state-of.the-art ICP-MS equipment Accurate size and size distribution possible Fit for monitoring if EU recommended nanodefinition is complied with No losses on physical surfaces Cons Poor mass accuracy Method still in it s infancy (need for dedicated sample preparation methods) Therefore: Future coupling of sp ICP-MS with separation technique such as FFF to improve NP size separation power Target of future coupled method: Food, feed and cosmetics monitoring Future legislative control of NPs

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57 Q1 Agilent 8800 ICP-QQQ Cell Q2 Detector 55

58 Standardisation of dispersion methods Aim: To produce a stable aqueous suspension of the dry nanoparticles with same characteristics across laboratories Energy input required (e.g. by manual shaking/vortexing/milling/ultrasound bath/ultrasound probe) Preferably without using stabilisers Ball-milling with ZrO 2 beads in diluted acetic acid Ultrasound probe sonication in Milli-Q water 56

59 At the forefront of nano-research: Preparation of biological samples prior to NP characterisation NPs in a liquid or tissue matrix Dilution of the matrix Degradation of the matrix Separation of NPs and matrix enzymatic chemical thermal chemical (NP-selective chemistry) physical Alkaline solubilisation Fractionation Acidic Wet ashing filtration centrifugation

60 Q: Why are properties of nanosized particles different from corresponding bulk material? A: High proportion of non-coordinated surface atoms Catalytic activity Redox activity (ROS formation) Refs.: Grainger and Castner, 2008 Oberdörster et al, 2007

61 Cross-laboratory results for dispersion of CuO-NH 3 + following standardised procedure Hydrodynamic diameter, z ave (by DLS) for 9 replicates in each lab. on 2 days Verdict: Room for improvement!

62 Q: Why are properties of nanosized particles different from corresponding bulk material? A: High proportion of non-coordinated surface atoms Refs.: Grainger and Castner, 2008 Oberdörster et al, 2007

63 Au/Rh - Ratio AF 4 -ICP-MS of AuNPs in rat s liver digested with TMAH 10 and 60 nm AuNPs in PBS were injected in rats tail vein Alkaline dissolution of liver tissue following stabilisation of AuNPs with BSA 10 TMAH extracts of liver homogenate containing 10 and 60 nm AuNPs Retention Time (min) Aqueous Aunanoparticle suspension (10 and 60 nm) first stabilised with BSA and then treated with TMAH (ph 13) Recoveries were % but separation was unsuccessful 60 Ref.: Schmidt et al. Anal. Chem. (2011)

64 Dispersion methods (3) CuO NPs with -NH 3+ or -COO - Z ave (nm) PDI ζ-potential (mv) CuO core 1408 ± ± 1.2 CuO-CH 2 -NH ± ± 0.5 CuO- COO ± ± 0,3 62

65 Before you start working.. Get the nanoparticles into a stable suspension, but how?

66 Dispersion methods (2) Standardization of the acoustic energy Dispersion & size of a nanomaterial in aqueous suspension depends on the delivered acoustic energy =acoustic power and sonication time Other testing labs should reach same deagglomeration (corresponding to 5 13 W using standardised procedure) 64

67 spicp-ms analysis of fractions collected after AF 4 separation Thermo Fisher icap Q 3 ms/60 kdwells Loeschner, et al., Anal., Bioanal. Chem. (2013), 405,

68 Q: Do the AgNPs dissolve during enzymatic digestion at of chicken meat? Techniques: spicp-ms and TEM Slight change in particle number size distribution after enzymatic sample prep! Loeschner, et al., Anal., Bioanal. Chem. (2013), 405,

69 Size and concentration of AuNPs in rat tissue determined by spicpms after TMAH or enzymatic treatment Number-based size distribution, o.d. (nm) Quantitative results (ng Au/g) Animal Alkaline Enzymatic Aqua regia (spicpms) (spicpms) (ICPMS) Mean RSD (%) Repeatability RSD (%) Both sample preparation methods give same AuNP size distribution Alkaline sample preparation gives more accurate quantitative results Ref.: Loeschner, K., Brabrand, M., Sloth, J.J., and Larsen, E.H., Anal., Bioanal. Chem. (2013) (DOI) /s y

70 AF 4 -DLS-ICP-MS fractogram of gold nanoparticles in aqueous suspension AFFF mobile phase: 0.05% SDS Noise characteristics of ICP-MS detection of 0.5 ng/ml Au 4 sizes (100 ms dwell time) and ionic standard Au/Rh - Ratio nm Au NPs 20 nm Au NPs 30 nm Au NPs 60nm Au NPs Hydrodynamic Diameter (nm) Au NP 60 nm Au NP 30 nm Retention Time (min) 0 Au (cps) Au NP 20 nm Au NP 10 nm Au Standard Time (min) Statement: Life is quite easy when working with stable nanoparticles in aqueous suspension Ref.: Schmidt et al. Anal. Chem. (2011)

71 "Nanoparticles in Food: Analytical methods for detection and characterisation" Pristine silver nanoparticles spiked to blank chicken meat as sample, then: Subjected to enzymatic digestion for o C Aim: Analyse and study fate of Ag NPs by size separation using AF 4 and ICP-MS detection

72 Optimized AF 4 fractionation of pristine AgNPs in aqueous suspension 1 ml/min for optimum selectivity and analysis time Cross flow rate of carrier, 50 mm HN 4 HCO 3 (ml/min) For further details of AF 4 optimisation see: Loeschner et. al, J. Chrom. A (2012)