Development and characterisation of polymeric microparticle of poly(d,l-lactic acid) loaded with holmium acetylacetonate

Abstract

Biodegradable polymers containing radioactive isotopes such as Holmium 166 (Ho) have potential applications as beta particle emitters in tumour tissues. It is also a gamma ray emitter, allowing nuclear imaging of any tissue to be acquired. It is frequently used in the form of complexes such as holmium acetylacetonate (HoAcAc), which may cause damages in tissues next to the targets cancer cells, as it is difficult to control its linkage or healthy tissues radiotherapy effects. Poly(d,l-lactic acid), PDLLA, was used to encapsulate holmium acetylacetonate (HoAcAc) using an emulsion solvent extraction/evaporation technique. Microspheres with sizes between 20-53 µm were extensively characterised. HoAcAc release from the microspheres was assessed through studies using Inductively Coupled Plasma - Optical Emission Spectroscopy, and the microspheres showed no holmium leakage after a period of 10 half-lives and following gamma irradiation. Thus, HoAcAc loaded microspheres are here presented as a potential system for brachytherapy and imaging purposes.

<p>Poly(3-hydroxi-butyrate-co-3-hydroxy-valerate) (PHB-HV) microparticles loaded with holmium acetylacetonate as potential contrast agents for magnetic resonance images</p>

“…Many inconveniences in the use of oxides and resins as matrixes to produce particles for medical therapies come from their long-time stability in the human body what brings a risk of embolization in healthy organs. Recently, the biodegradable matrixes are being preferred to host radionuclides 56. Their lower time of stability gives them properties of controlled delivery systems: (1) release time of radionuclides is longer than in free formulations, (2) they maintain plasma concentration for a long time, (3) they also locomote in vivo through physical and/or chemical principles 57.…”