Resumo

MENDOZA-MUNOZ, Néstor; PINON-SEGUNDO, Elizabeth; GANEM-QUINTANAR, Adriana  e  QUINTANAR-GUERRERO, David. Preparation and in vitro evaluation of biodegradable polymeric nanoparticles as ultrasound contrast agent. TIP [online]. 2007, vol.10, n.1, pp.14-20. ISSN 1405-888X.

Ultrasound contrast agents available in the market do not allow the efficient detection of tumors in diverse organs. The miniaturization of this kind of systems on nanometric scale could solve this problem. The purpose of this work was to adapt the solvent displacement method in order to obtain the "hollow" nanoparticles from the encapsulation of a sublimate nucleus (naphthalene), characterizing them for their size, density and morphology. An in vitro evaluation by means of a commercial ultrasound system was also performed. Nanoparticles with a diameter of 50-400 nm and an entrapment efficiency of 66.55% of naphthalene were obtained. Lyophilization allow to take off 98% of the encapsulated amount of naphthalene, however, the micrographs obtained by scanning electronic microscopy and transmission, did not demonstrate the presence of pores or hollows in the polymeric matrix. In addition, the density of the preparations with naphthalene was similar to the systems with nanospheres formed only by polymer. Nevertheless, in vitro results suggest an increase in echogenicity for those preparations containing nanoparticles, in comparison with those solutions without nanoparticles.

Palavras-chave : Contrast agents; solvent displacement; lyophilization; nanoparticles; ultrasound.