Modified mineral-based fillers with enhanced retention of at least one active ingredient and/or enhanced antimicrobial capabilities are described. The materials comprise at least one mineral-based filler subjected to at least one modification process, which may be either a cationic modification process, a surface adsorption process, a surface retention process, or a combination thereof, with at least one active ingredient, followed by at least one thermal treatment. The at least one active ingredient may be a metal substance or other biocide, fungicide, mildewcide, antibiotic, insecticide, preservative, or antimicrobial agent. Methods for enhancing the antimicrobial activity of products in applications such as polymers, clothing, surgical equipment, coatings, and paints are also described.