The present invention describes a polyamide textile fiber comprising conjugated nanoparticles homogeneously dispersed in the fiber, selected from polyethylene glycol-conjugated platinum nanoparticles, hyaluronic acid-conjugated gold nanoparticles and mixtures thereof. The invention also describes how to obtain it as well as its use in a cosmetic skin treatment as a system for the release of said conjugated nanoparticles.