TGF-β growth factor and its latent complex are conjugated to magnetic micro- or nanoparticles and to magnetic micro- or nanodiscs. By exposing the resulting conjugates to magnetic fields, the TGF-β growth factor can be released from its latent complex in vivo, potentially making it useful in tissue engineering and regenerative medicine. And by exposing a conjugate of TGF-β growth factor and a magnetic particle to a sufficiently strong, radiofrequency magnetic field, the TGF-β growth factor can be denatured and thereby deactivated, potentially making it possible to avoid triggering tumorigenesis, atherosclerosis, fibrotic disease, and cancer.