Figure 3.

Coal fly ash (CFA) creates a negative particle-protein complex. (A) Zeta potential measurements of CFA 2691, human β-defensin-3 (HBD-3), and HBD-3–CFA suspensions. CFA 2691 had a negative zeta potential, HBD-3 had a positive zeta potential. When they were coincubated, $\text{HBD}-3+\text{CFA}2691$ formed a less negative complex compared with CFA alone ($n=6$). (B–F) Zeta potential measurements of several ambient particulate matters (PMs). (B) CFA 2691, (C) CFA 2690, (D) CFA 2689, (E) urban PM, and (F) volcanic ash all had a negative surface charge and formed negatively charged complexes when coincubated with increasing concentrations of lysozyme ($n=3$).