Production and characterization of¹⁶⁶Ho polylactic acid microspheres

Abstract

Microsphere and particle technology with selective transport of radiation represents a new generation of therapeutics. Poly-L-lactic acid (PLLA) microspheres loaded with holmium-166 acetylacetonate ((166)Ho-PLLA-MS) are novel microdevices. In this research, (165)HoAcAc-PLLA microparticles were prepared by the solvent evaporation technique. Microspheres were irradiated at Tehran Research Reactor. The diameter and surface morphologies were characterized by particle sizer and scanning electron microscopy before and after irradiation. The complex stability, radiochemical purity, and in vivo biodistribiotion were checked in the final solution up to 3 days. In this study, (166)Ho-PLLA spherical particles with a smooth surface and diameter of 20-40 µm were obtained, which were stable in vitro and in vivo studies. Neutron irradiation did not damage the particles. The ease with which the PLLA spheres could be made in the optimal size range for later irradiation and their ability to retain the (166)Ho provided good evidence for their potential use in radioembolization.

Preparation and evaluation of 188Re sulfide colloidal nanoparticles loaded biodegradable poly (L‐lactic acid) microspheres for radioembolization therapy

“…Furthermore, according to the results of previous studies on the biodegradable PLLA microspheres irradiated in a reactor, such as 186 Re‐PLLA and 166 Ho‐PLLA to radioembolization of liver tumors, neutron activation strongly decreased the average molecular weight of the microspheres. Also, the heat production from gamma radiation melted the microspheres, so the microspheres were becoming misshaped and conglomerates and also likely led to the appearance of pores on the microsphere surface.…”

“…For effective radioembolization, the radionuclide must be a short‐lived high energy beta emitter. 90 Y, 186 Re, 188 Re, and 166 Ho radioisotopes have been tested for radioembolization, but only 90 Y‐microspheres are currently in routine clinical use. 90 Y glass‐based Thera‐Sphere1 (Nordion, Canada) and 90 Y resin‐based SIR‐Spheres1 (SIRTex, Australia) microspheres are commercially available radioembolic agents for radioembolization of liver tumors.…”

“…166 Ho‐PLLA and 186 Re‐PLLA have been investigated previously. These radiomicrospheres are produced by irradiation in a reactor.…”

Radiochemical processing of nuclear-reactor-produced radiolanthanides for medical applications

“…Like several other radiolanthanides, the use of 166 Ho-EDTMP has been explored for bone pain palliation [128]. The use of 166 Ho loaded poly(L-lactic acid) (PLLA) microspheres, which are commercially available as QuiremSpheres, was investigated for the treatment of liver malignancies [127,[129][130][131]. Due to the average diameter of these microspheres of 30 mm, the microspheres lodge preferentially in the microvasculature surrounding the tumor, maximizing tumorcidal effects and minimizing the effects on healthy liver parenchyma.…”

Contaminación de suelos y aguas por hidrocarburos en Colombia. Análisis de la fitorremediación como estrategia biotecnológica de recuperación

“…Conocidos como sustancias naturales originadas a partir de algas acuáticas establecidas durante millones de años, gracias a la materia orgánica formada en la superficie de la tierra, proceso iniciado con la fotosíntesis, la cual hace parte del ciclo del carbono; y a través del tiempo geológico este aporte ha producido grandes cantidades de materia fósil (Yavari et al, 2015). Dichas sustancias están conformadas principalmente de compuestos con diferente solubilidad, volatilidad, y debido a que son formadas únicamente por átomos de carbono e hidrógeno son compuestos orgánicos susceptibles para ser biodegradados, ya sea eliminados o transformados en sustancias menos tóxicas tanto en suelos como en cuerpos de agua contaminadas, permitiendo de este modo el análisis de estudios con el fin de diseñar estrategias fitorremediadoras para contribuir con su degradación y por ende con la descontaminación de los suelos y agua.…”