AZEVEDO, MARIANGELA de B.M. deMELO, VITOR H.S.SOARES, CARLOS R.J.GAMARRA, LIONEL F.BARROS, CAIO H.N.TASIC, LJUBICA2019-12-192019-12-192019AZEVEDO, 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. <b>International Journal of Nanomedicine</b>, v. 14, p. 6869-6889, 2019. DOI: <a href="https://dx.doi.org/10.2147/IJN.S191274">10.2147/IJN.S191274</a>. Disponível em: http://repositorio.ipen.br/handle/123456789/30466.1178-2013http://repositorio.ipen.br/handle/123456789/30466Introduction: 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.6869-6889openAccesspolymersholmiumholmium 166acetylacetonecontrast mediamagnetic resonanceneoplasmstherapymicrospheresArtigo de periódico1410.2147/IJN.S191274https://orcid.org/0000-0002-7982-178979.87185.67