Obtenção e caracterização de microbolhas com cápsulas de policaprolactona em ultrassom visando aplicações biomédicas

Abstract

The objective of this work is to assess two polycaprolactone (PCL) porous capsules of different molecular masses applied as ultrasound contrast agents (UCAs). The compared features are capsule composition, stability, compressibility, ultrasonic cavitation, and ultrasonic backscattering. The acoustic response of porous UCAs produced with two molecular masses, 10,000 and 45,000 mg/mol of PCL capsules, is compared for the first time, by evaluating the backscatter signals, the temporal stability, and the response to increasing acoustic pressure intensities. The variation in molecular weight resulted in small variations in the elastic module, in which PCL45 had a more elastomeric behavior than PCL10. Porous PCL10 and PCL45 UCAs presented greater stability than phospholipid UCAs and thinner capsule thickness than polymeric ones (16 to 26 nm). UCAs with PCL45 proved to be superior to those with PCL10, since they showed greater backscattering in a variety of frequencies, as well as greater response to diferente acoustic pressures allowed in clinical use of UCAs. PCL is than considered a candidate for UCAs capsules in the polymer category. Both PCL capsules have potential for biomedical applications, either for contrast ultrasound as well as for HIFU treatments. In the latter, there are two possible uses, raise image contrast of a specific tissue using ultrasound, and ablate the area using higher intensity. Also, PCL is compatible with a wide variety of other polymers and can be copolymerized with other monomers, which expands its possibilities for future applications.