The Enceed T cell Activation reagent induces T cell activation and expansion in enriched T cells or PBMCs. The Enceed T cell Activation reagent is composed of biodegradable matrix-coated nanoparticles conjugated with mouse anti-human CD3 and mouse anti-human CD28 antibodies. The small sized particulate structure of the activation reagent enables its easy removal by media washing or centrifugation.