The present disclosure, among other things, provides a composition including a nanoscale core; a plurality of capping agent entities associated on the core; an outer encapsulant layer; and a plurality of dopant entities distributed at locations selected from the group consisting of: on or within the nanoscale core, on or between capping agent entities, on or within the encapsulating layer, and combinations thereof. Provided technologies can achieve unprecedented levels of dopant entity density and/or surface localization, which, for a SE(R)RS-active agent dopant, results in dramatically improved signal intensity and/or imaging sensitivity.