The purpose of this Article is to characterize polymeric particles of poly(methylmethacrylate) (PMMA) synthesized in the presence of one of two different quaternary ammonium surfactants (QACs): cetyltrimethylammonium bromide (CTAB) or dioctadecyldimethylammonium bromide (DODAB). The methods used are dynamic light scattering for sizing, polydispersity and zeta potential analysis, scanning electron microscopy (SEM) for morphology visualization, and plating plus colony-forming unities (CFU) counting for the determination of antimicrobial activity. The results point out the high QAC concentration required to obtain cationic and bioactive antimicrobial particles with good colloidal stability and a permanent load of the polymeric network with QACs. Over a range of micromolar QAC concentrations, there is remarkable antimicrobial activity of PMMA/CTAB or PMMA/DODAB particles, which is much higher than those determined for the QACs by themselves. Loading the biocompatible polyacrylate particles with QACs is a facile, fast, low-cost approach to obtaining highly efficient antimicrobial nanoparticles.