Nanoparticle compositions include a plurality of spherical-shaped nanoparticles and a plurality of coral-shaped metal nanoparticles, each coral-shaped metal nanoparticle having a non-uniform cross section and a globular structure formed by multiple, non-linear strands joined together without right angles. The nanoparticle compositions can be one-part or multi-part compositions. Nanoparticle compositions can have a mass ratio of spherical-shaped to coral-shaped nanoparticles of about 5:1-20:1, about 7.5:1-15:1, about 9:1-11:1, or about 10:1 and/or a number ratio of spherical-shaped to coral-shaped nanoparticles of about 50:1-200:1, about 75:1-150:1, about 90:1-110:1 or about 100:1. The nanoparticle compositions can be used for various purposes, including as an antimicrobial (e.g., anti-viral, anti-bacteria, or anti-fungal composition), fuel additive, or treating fabrics.