NP Agglomeration Kinetics in Holtfreter’s Solution 1 S. George, T. Xia, and A. Nel et al. ACS Nano, 5(3), 2011, Improved dispersion and stability in the presence of alginate as the dispersing agent

Toxicity Screening in Zebrafish 2 S. George, T. Xia, and A. Nel et al. ACS Nano, 5(3), 2011,

Quantum Dot Mediated Toxicity 3

Dissolution Kinetics of ZnO and Fe-ZnO and Their Physical-Chemical Properties George, Pokhrel, Maedler et al. ACS Nano, 2010, 4, 15–29. 4

Case Study III – MWCNTs AP-MWCNT 500 nm Inflammation, inflammasome

MWCNT Combinatorial Library 6 X. Wang, T. Xia, and A.E. Nel et al. ACS Nano, 4(12),

Zeta Potential & Size Analyses of MWNTs 7 MediumAP-MWCNTPD-MWCNTCOOH-MWCNT Zeta potential (mV) H2OH2O PBS BEGM DMEM Hydrodynamic size (nm) H2OH2O PBS BEGM DMEM  In H 2 O: Slightly negative zeta potentials for AP-MWCNT and PD- MWCNT and much higher zeta potential for COOH-MWCNT  Similar zeta potentials in PBS, BEGM, and DMEM – DLVO theory fails at high ionic strength  COOH-MWCNT was much better dispersed in H 2 O compared to AP- MWCNT and PD-MWCNT, but not in PBS, BEGM, and DMEM X. Wang, T. Xia, and A.E. Nel et al. ACS Nano, 4(12),

n-Octanol/Water Partitioning by UV-vis 8 H2OH2O Hydrophobicity index (%) = × 100 % A 0 - A 1 A0A0 MWCNT in medium Absorbance at 550 nm (A 0 ) Add n-octanol vortex Absorbance at 550 nm (A 1 ) The relatively high hydrophobicity of AP-MWCNTs and PDMWCNTs is a major factor contributing to their poor dispersion, while the electrostatic repulsion by the carboxyl groups promotes COOH- MWCNT hydrophilicity and thus better dispersion. X. Wang, T. Xia, and A.E. Nel et al. ACS Nano, 4(12),

High Ionic Strength Contributes Tube Agglomeration 9 1/10 PBS 1/5 PBS 1/2 PBS 1x PBS 1x PBS w/o Ca 2+ & Mg % NaCl DI H 2 O COOH-MWCNT in PBS mM X. Wang, T. Xia, and A.E. Nel et al. ACS Nano, 4(12),

Improved MWCNT Dispersion in PBS by BSA 10 X. Wang, T. Xia, and A.E. Nel et al. ACS Nano, 4(12), COOH-MWCNT in PBS with BSA 1/10 PBS 1/5 PBS 1/2 PBS 1x PBS 1x PBS w/o Ca 2+ & Mg % NaCl DI H 2 O PBS+BSA PBS * * *

MWCNT Dispersion Characterization in BEGM 11 BEGMBEGM+DPPCBEGM+BSABEGM+BSA+DPPC PD-MWCNTs AP-MWCNTs MWCNT-COOH X. Wang, T. Xia, and A.E. Nel et al. ACS Nano, 4(12),

MWCNT Stability Measurement in BEGM 12 MWCNT in medium Absorbance at 550 nm BEGM+DPPC BEGM+BSA BEGM+BSA+DPPC BEGM AP-MWCNT 20 BEGM+DPPC BEGM+BSA BEGM+BSA+DPPC BEGM PD-MWCNT 20 BEGM+DPPC BEGM+BSA BEGM+BSA+DPPC BEGM COOH-MWCNT 20 X. Wang, T. Xia, and A.E. Nel et al. ACS Nano, 4(12),

MWCNT Dispersion Characterization in DMEM 13 PD-MWCNTs AP-MWCNTs MWCNT-COOH X. Wang, T. Xia, and A.E. Nel et al. ACS Nano, 4(12), DMEMDMEM+DPPCDMEM+BSADMEM+BSA+DPPC cDMEM

MWCNT Stability Measurement in DMEM 14 AP-MWCNT DMEM+DPPC DMEM+BSA DMEM+BSA+DPPC DMEM cDMEM 20 PD-MWCNT DMEM+DPPC DMEM+BSA DMEM+BSA+DPPC DMEM cDMEM 20 COOH-MWCNT DMEM+DPPC DMEM+BSA DMEM+BSA+DPPC DMEM cDMEM 20 MWCNT in medium Absorbance at 550 nm X. Wang, T. Xia, and A.E. Nel et al. ACS Nano, 4(12),

Dispersion Enhances Fibroblast Proliferation 15 D COOH-MWCNT ControlStarvation ND AP-MWCNT D AP-MWCNT ND PD-MWCNT D PD-MWCNT ND COOH-MWCNT 0 % 5 % 10 % 15 % 20 % 25 % 30 % 35 % Proliferation rate (EdU-positive cells) * * * X. Wang, T. Xia, and A.E. Nel et al. ACS Nano, 4(12), * p<0.05 compared to the control.

Summary Highly stable TiO 2 nanoparticle dispersions in different cell culture media were obtained by using FBS, BSA, or BSA&DPPC as dispersing agents A general dispersion method could be applied for many other metal or metal oxide nanoparticles Dissolution characterization is critical for nanomaterials such as ZnO and QDs Hydrophobicity and dispersion state play important roles in MWCNT toxicity studies 16

Acknowledgement s Dr. Tian Xia Dr. Saji George Dr. Huan Meng Dr. Xiang Wang Dr. Haiyuan Zhang Grant Support: NSF: DBI‐ Dr. Sijie Lin Dr. Angela Ivask Dr. Cecile Low-Kam Courtney R. Thomas LinJiang Li Dr. Jeffrey I. ZinkDr. Adré E. Nel