Poly(3-hydroxi-butyrate-co-3-hydroxy-valerate) (PHB-HV) microparticles loaded with holmium acetylacetonate as potential contrast agents for magnetic resonance images
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International Journal of Nanomedicine
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Introduction: Biodegradable polymers that contain radioactive isotopes such as Holmium 166
have potential applications as beta particle emitters in tumor tissues. Also, Ho(III) is paramagnetic,
which makes it suitable as a contrast agent for magnetic resonance (MR) images.
Methods: Holmium acetylacetonate (Ho(acac)3) loaded poly(3-hydroxy-butyrate-co-3-
hydroxy-valerate) microspheres, with 5% or 8% of 3-hydroxy-valerate (HV), were prepared
by emulsification/evaporation process within 20–53 μm size. Microspheres characterization
was done using scanning electron microscopy, energy-dispersive X-ray, and infrared spectroscopies.
The release of holmium(III) in sodium phosphate buffer (pH 7.4) was followed for 9
days with inductively coupled plasma. Finally, T2 and T2* magnetic resonance images (MRI)
were acquired and compared with the MRI of the inclusion complex of holmium acetylacetonate
in some β-cyclodextrins.
Results: Holmium acetylacetonate loading, evaluated by thermogravimetry, was up to 20 times
higher for copolymer with 5% of HV. It was shown that microspheres loaded with Ho(acac)3
exhibited an accumulation of Ho(III) on their surfaces but were stable over time, as no expressive
release of holmium(III) was detected in 9-day exposition to sodium phosphate buffer. Holmium
acetylacetonate in both microspheres or inclusion complexes was very efficient in obtaining T2
and T2* weighted images in magnetic resonance, thus, might be used as contrast agents.
Conclusion: This is the first description of the use of inclusion complexes of holmium
acetylacetonate in biodegradable polymers as contrast agents. New investigations are underway
to evaluate the resistance of PHB-HV polymer microparticles to nuclear activation to
assess their potential for use as radiopharmaceuticals for the treatment of liver cancer.
Como referenciar
AZEVEDO, MARIANGELA de B.M. de; MELO, VITOR H.S.; SOARES, CARLOS R.J.; GAMARRA, LIONEL F.; BARROS, CAIO H.N.; TASIC, LJUBICA. Poly(3-hydroxi-butyrate-co-3-hydroxy-valerate) (PHB-HV) microparticles loaded with holmium acetylacetonate as potential contrast agents for magnetic resonance images. International Journal of Nanomedicine, v. 14, p. 6869-6889, 2019. DOI: 10.2147/IJN.S191274. Disponível em: http://repositorio.ipen.br/handle/123456789/30466. Acesso em: 30 Dec 2025.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.