Development of a Telemetric System for Postoperative Follow-up of Vascular Surgery Procedures: In Vitro Model.

BACKGROUND: Because of the unique electromagnetic characteristics of the magnetoelastic microwire, the changes in the pressure of a fluid will provoke a variation of the mechanical pressure on the sensor, which will cause a variation of its magnetization that will be detectable wirelessly. Thus, a wireless system can be developed for following up vascular surgery procedures. METHODS AND RESULTS: The sensor consists of a magnetoelastic microwire ring, which was integrated into an in vitro model with pulsatile flow. Different degrees of stenosis were simulated in different locations both in bovine artery as well as in a polytetrafluoroethylene anastomosis. A Fourier analysis of the registered signals and a statistical analysis using Pearson test and receiver operating characteristic (ROC) curves were made. A Pearson index of 0.945 (P<0.001) was obtained between the invasive pressure of the fluid and the power of the signal transmitted by the sensor in bovine artery. The sensor obtained very good ROC curves upon analyzing the signals registered, both in the case of preanastomotic stenosis (area under the curve [AUC], 0.98; 95% CI, 0.97-1.00), of anastomosis (AUC, 0.93; 95% CI, 0.86-0.99), as well as distal (AUC, 0.88; 95% CI, 0.79-0.98), compared to the control group. CONCLUSIONS: The magnetoelastic microwire has shown that it is capable of detecting, locating, and quantifying the degree of stenosis in bovine artery, as well as in a latero-terminal anastomosis, with a high statistical potency. For the first time, a wireless in vitro sensor has been developed for the postoperative follow-up of vascular surgery procedures.

Structural reorganization of cylindrical nanoparticles triggered by polylactide stereocomplexation.

Co-crystallization of polymers with different configurations/tacticities provides access to materials with enhanced performance. The stereocomplexation of isotactic poly(L-lactide) and poly(D-lactide) has led to improved properties compared with each homochiral material. Herein, we report the preparation of stereocomplex micelles from a mixture of poly(L-lactide)-b-poly(acrylic acid) and poly(D-lactide)-b-poly(acrylic acid) diblock copolymers in water via crystallization-driven self-assembly. During the formation of these stereocomplex micelles, an unexpected morphological transition results in the formation of dense crystalline spherical micelles rather than cylinders. Furthermore, mixture of cylinders with opposite homochirality in either THF/H2O mixtures or in pure water at 65 °C leads to disassembly into stereocomplexed spherical micelles. Similarly, a transition is also observed in a related PEO-b-PLLA/PEO-b-PDLA system, demonstrating wider applicability. This new mechanism for morphological reorganization, through competitive crystallization and stereocomplexation and without the requirement for an external stimulus, allows for new opportunities in controlled release and delivery applications.