Geração e caracterização de microbolhas monodispersas com revestimento lipídico utilizando dispositivos de entroncamento microfluídicos

Abstract

There is a growing currently interest in the use of microbubbles in various fields of medicine, pharmacology and chemistry, as well as in the food industry. There are several techniques used for the production of monodisperse microbubbles, such as coaxial electrohydrodynamic atomization (CEHDA), insonation methods and microfluidic devices. Some of these techniques require safety procedures during the application of intense electric fields (eg CEHDA) or soft microlithography equipment for the production of microfluidic devices, which require a clean room and controlled environment, avoiding the contamination in the microlithography process of the devices. The microfluidic trunking devices have the lowest dispersion rate of microbubble size generated, compared to the Insonation and CEHDA techniques. This work presents the process of generation of lipid-coated microbubbles by the T-junction channel junction method using clinical-use micropipettes inserted into microfluidic devices developed by a 3D printer, where microbubbles of different sizes were generated in relation to the different micropipettes used during the experiments. The diameters of the microbubbles generated were 16.55 μm at 57.7 μm, according to the micropipette used, and polydispersity index close to 1%. With these results it was possible to elaborate a characteristic curve relating the diameter of the micropipette as a function of the diameter of the microbubble to be generated, by means of a 2nd order polynomial. The results were compared to other studies that used the lipid matrix as coating and air as the gas phase of the microbubble. The percentage error was between 2.75% and 6.62% and absolute error between 0.11 μm and 4.64 μm. According to the elaborated characteristic curve, the microfluidic device allows the production of microbubbles of sizes suitable for clinical use, using a micropipette with internal diameter of less than 3 μm. In the continuity of this work, studies were carried out on the microbubble generation at high liquid flow rate and gas flow and microbubble stability due to alteration of the coating (sunflower oil and emulsifier) ​​in different mass proportions and the association of emulsifiers. The microbubble production rate was 1800 bubbles per second, with an average diameter of 42.8 μm and a polydispersity index of 3%. For the stability analysis, it was possible to measure the increase in stability by the association of different emulsifiers in the coating layer. The stability obtained was between 10 s and 900 s for a microbubble with an initial diameter of approximately 25 μm.