This study examined the structure, thermal property, and ion adsorption of silk particles. The particles were prepared by attritor-bead mill combination, using alkaline (pH 10) charge repulsion and surfactant steric repulsion methods. Both methods produced particles with a dominant beta-sheet structure, similar to the silk fibre. There was no significant difference in the decomposition temperatures for either the silk fibre or the micro/nano silk particles. An important finding from this study is clear evidence of reduction of amorphous content during the final stage of powdering using the bead mill. As a result, despite reduction in beta-sheet crystallites with the progressive milling, the relative beta-sheet content actually increased during this process. However, intermolecular forces between the beta-sheets reduced significantly and hence the XRD results showed significant reduction in crystallinity in nano silk particles but crystal forming segments remained with beta-sheet conformations after milling. The structural change influenced the ion-adsorption property where particle-size reduction resulted in a significant increase in both the rate and volume of HCrO4- adsorption. (C) 2014 Elsevier B.V. All rights reserved.