Obtenção de compósito para utilização como marcadores radiopacos no estudo do tempo de trânsito colônico.

Abstract

Constipation is a chronic problem that affects many patients in the world and can be defined as any difficulty in performing defecation, requiring greater effort than usual. One of the previous assessments of treatment in constipation includes the study of colonic transit time that is performed using the radiopaque markers, some of which are polymers added with charges that attribute radiopacity to the material. Polypropylene is a colorless, odorless, non-toxic plastic and considered one of the lightest plastics, has an apolar structure, is chemically inert, and is only susceptible to dissolution by non-polar solvents. Carbonate and calcium phosphate are among the materials most intensively used as inorganic carg, mainly for regeneration of bone tissue due to their chemical similarity, radiopacity and bioactivity. Due to these characteristics, they have the potential to be used to obtain a radiopaque composite for the measurement of colonic transit time. Therefore, the present work aims to obtain and characterize radiopaque markers for the study of colonic transit time. The research was carried out at the UFCG, at CERTBIO. The materials used were Polypropylene, Calcium Phosphate and Calcium Carbonate. To obtain the composite, the polypropylene was mixed to the load and then extrused in a monorail extruder. The polymeric matrix was added with concentrations of 5% and 10% of Calcium Phosphate and Calcium Carbonate, and later characterized by Scanning Electron Microscopy, X-ray Dispersive Energy Spectroscopy, Wettability by contact angle, Radiopacity, Degradation by Hydrochloric Acid and Degree of Swelling. In the MEV results before degradation the presence of uniformly distributed pores and particles on the surface was observed and after the degradation test the surface degradation of the samples was observed, leaving the internal charges in the polymer matrix exposed. The EDS test presented a high percentage of the Carbon and Oxygen elements characteristic of Polypropylene molecules, besides Calcium and Phosphorus coming of the Calcium Carbonate and Hydroxyapatite. Results of Wettability by contact angle suggest that the material has a hydrophilic profile. All the composites obtained in this research presented sufficient radiopacity when compared to radiolabels used in the market with barium sulfate. In the degradation assay a low degradation of the samples was observed. In the results of the swelling test, it was seen that the increase of the load influences the swelling of the samples, since in higher concentrations of load the reduction of the swelling of the samples takes place. Through the results obtained in the composites studied in this research it can be concluded that they are promising in the use as radiopaque markers in the study of colonic transit time. It is also concluded that the composites can present lower cost / benefit if it is obtained with the calcium carbonate that presents lower cost when compared to Hydroxyapatite that showed similar effectiveness in the radiopacity assay.