Polymeric particles are provided for use in therapeutic and/or diagnostic procedures. The particles include poly[bis(trifluoroethoxy)phosphazene and/or a derivative thereof which may be present throughout the particles or within an outer coating of the particles. The particles may also include a core having a hydrogel formed from an acrylic-based polymer. Such particles may be provided to a user in specific selected sizes to allow for selective embolization of certain sized blood vessels or localized treatment with an active component agent in specific clinical uses. Particles of the present invention may further be provided as color-coded microspheres or nanospheres to allow ready identification of the sized particles in use. Such color-coded microspheres or nanospheres may further be provided in like color-coded delivery or containment devices to enhance user identification and provide visual confirmation of the use of a specifically desired size of microspheres or nanospheres.