Fractionating Nanosilver: Importance for Determining Toxicity to

Nov 17, 2010 - U.S. Army Engineer Research and Development Center, Vicksburg, Mississippi 39180, United States, Department of Civil and Environmental ...
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SUPPORTING INFORMATION Fractionating Nanosilver: Importance for Determining Toxicity to Aquatic Test Organisms Alan J. Kennedy†*; Matthew S. Hull‡; Anthony J. Bednar†; Jennifer D. Goss†; Jonas C. Gunter§; Jennifer L. BouldinΩ; Peter J. Vikesland‡; Jeffery A. Steevens† * U.S. Army Engineer Research and Development Center Environmental Laboratory, EP-R 3909 Halls Ferry Rd Vicksburg, MS, 39180 Voice: 601-634-3344 Fax: 601-634-2263 [email protected]

† U.S. Army Engineer Research and Development Center, Vicksburg, MS, 39180 ‡Department of Civil and Environmental Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA § Luna Innovations, Blacksburg, VA Ω Arkansas State University, Jonesboro, AR

Number of pages in Supporting Information (including cover): 7 Number of tables in Supporting Information: 4 Number of figures in Supporting Information: 2

S1

Table S1. Quality control measures for the dynamic light scattering data presented in Table 1 for the tested Nano-silver (nAg) materials. The baseline index is provided as a measure of the quality of fit to the algorithm in the DLS software. PI = polydispersity index; BI = baseline index Hydrodynamic Diameter by intensity (nm) Material MQ water MHRW

ASAP-nAg

PI = 0.13; BI = 7.6

PI = 0.06; BI = 8.0

Citrate-nAg

PI = 0.29; BI = 8.4

PI = 0.28; BI = 8.8

EDTA-nAg

PI = 0.27; BI = 6.4

PI = 0.29; BI = 3.9

NanoComposix (10 nm)

PI = 0.39; BI = 0.0

PI = 0.22; BI = 8.8

NanoComposix (20 nm)

PI = 0.18; BI = 6.2

ND

NanoComposix (50 nm)

PI = 0.19; BI = 9.6

ND

NanoComposix (80 nm)

PI = 0.19; BI = 6.1

PI = 0.20; BI = 8.9

Polyvinyl pyrrolidone Ag

PI = 0.24; BI = 7.5

PI = 0.24; BI = 6.5

S2

Table S2. Electrophoretic mobility and zeta potential of nanosilver suspensions in milli-Q (MQ) water and moderately hard reconstituted water (MHRW) after 5 minutes and 24 hours of interaction with the media. In MQ Material

In MHRW (5 min.)

In MHRW (24h)

Electrophoretic Mobility (m2/v*s)

Zeta (mV)

Electrophoretic Mobility (m2/v*s)

Zeta (mV)

Electrophoretic Mobility (m2/v*s)

Zeta (mV)

Citrate-Ag

-3.6 ± 0.2

-46 ± 3

-2.1 ± 0.1

-27 ± 1

-1.3 ± 0.2

-17 ± 3

EDTA-Ag

-2.6 ± 0.2

-33 ± 2

-1.7 ± 0.2

-22 ± 2

-2.0 ± 0.1

25 ± 1

NC10-Ag

-1.7 ± 0.1

-21 ± 2

0.4 ± 0.3

5±4

-0.6 ± 0.2

-8 ± 3

NC20-Ag

-1.8 ± 0.1

-23 ± 1

-1.7 ±0.1

-21 ± 2

-0.8 ± 0.5

-11 ± 6

NC50-Ag

-2.7 ± 0.1

-34 ± 1

-0.9 ± 0.7

-12 ± 4

-1.6 ± 0.1

-21 ± 1

NC80-Ag

-1.5 ± 0.1

-20 ±1

-0.9 ± 0.1

-11 ± 1

-1.9 ± 0.1

-24 ± 2

PVP-Ag

-1.1 ± 0.1

-15 ± 1

-0.7 ± 0.1

-9 ±1

-0.5 ± 0.3

-6 ± 4

S3

Table S3. Silver (Ag) measured in the unmodified stock, a supernatant of the stock produced by ultracentrifugation at 100,000 x g for 60 minutes, percent dissolved in the stock measured by field flow fractionation (FFF) and percentage of nAg in the supernatant of the high Daphnia magna and Pimephales promelas exposure concentrations following ultracentrifugation.

Material

Stock concentration Supernatant in milli-Q concentration water (µg/L) (µg/L)

% Ag in stock supernatant

% dissolved by FFF

% Fractionated % Fractionated Silver in Silver in highest highest MHRW MHRW concentration concentration (P. promelas) (D. magna)

Calculated % fractionated at LC50 (P. promelas)

ASAP-Ag

10,300

NA

NA

NA

57%

57%

16%

Citrate-Ag

5,550

1100

20%

7%

6%

25%

21%

EDTA-Ag

15,800

520

4%

4%

7%

2%

3%

NC10

5,170

374

7%

5%

9%

10%

11%

NC20

10,147

610

6%

4%

7%

7%

7%

NC50

10,372

351

3%

4%

7%

7%

6%

NC80

1,560

36.8

2%

6-8%

ND

5%

4%

PVP-Ag

89,100

2750

3%

3%

3%

NA

NA

S4

Table S4. Change in total and fractionated (dissolved) silver concentrations of nanosilver particles after 48-h exposure to the fish Pimephales promelas. The percent increase or decrease in silver concentrations is provided for the no observable effect concentration (NOEC). Asterisks indicate a value below detection limits.

Material

Effect level (% survival)

NanoComposix 10

Total Silver (µg/L)

Fractionated Silver (µg/L) 0 48 Percent hours hours Change

0 hours

48 hours

Percent Change

NOEC (95 ± 6%)

22.4

18.3

-18%

2.6

3.1

+20%

NanoComposix 80

NOEC (100 ± 0%)

81.1

69.7

-14%

0.6

3.3

+432%

NanoComposix 80

NOEC (97 ± 6%)

93.1

82.8

-11%

2.0

3.4

+73%

EDTA-nAg

NOEC (98 ± 5%)

18.0

8.5

-53%

0.5 *

1.1

+120%

EDTA-nAg

NOEC (90 ± 8%)

31.5

20.0

-37%

1.3

2.7

+108%

S5

(a)

(b)

(c)

(d)

(f)

(e)

(g)

Figure S1. Field flow fractionation analysis of nano silver suspensions for (a) citrate-Ag (b) EDTA-Ag, (c) NC10, (d) NC20, (e) NC50, (f) NC80 and (g) PVP-Ag. The left peak corresponds to the dissolved concentration. S6

(a)

Percent Survival

100

AgNO3 (3 tests) ASAP-nAg

80

Citrate-nAg EDTA-nAg

60

NC10 NC20 NC50

40

NC80 PVP-nAg

20 0 0.1

1

10

100

Log Total Silver (ug/L) (b)

Percent Survival

100 80 60 40 20 0 1

10

100

1000

Log Total Silver (ug/L) Figure S2. Dose response for Daphnia magna (a) and Pimephales promelas (b) exposed to silver nitrate (AgNO3) and nanoparticle suspensions.

S7