Comparing Oxygen Plasma, Hydrogen Peroxide and Flame Treatments of Polyamide Tubes to Hydrophilic Coating Adhesion

The incorporation of minimally invasive practices in surgical procedures has provided many facilities and benefits compared to equivalent traditional surgical techniques1. Through small localized incisions and using specific equipment, surgical management is restricted only to the diseased area and thus preserves the peripheral structures. This reduces the need for blood replacement, the length of hospital internment, the likelihood of infections, and the postoperative pain1–6 . However, these new techniques also have some disadvantages. In the case of endovascular procedures one of the biggest problems is the trauma and injury caused to blood vessel walls due to friction during the introduction of the device2,3,5,6 . Hydrophiliccoated catheters have contributed to further broadening the range of benefits offered by minimally invasive surgery through a significant reduction in the endovascular friction between the device and blood, as well as an increase in the biocompatibility of catheters. Hydrophilic coatings are polar materials and have high affinity for liquids of the same nature as blood, making the interface between them slide more easily3 . Moreover, the hydrophilic coatings have given positive results in tests for cytotoxicity, systemic toxicity, and acute intracutaneous reactivity, among others, demonstrating that they also satisfy requirements related to biocompatibility2,3 . Generally, methods to obtain a hydrophilic polymeric coating on another polymer component or device can be divided into three stages: (i) treatment of the device surface, (ii) deposition of the coating and (iii) curing of the coating. The surface treatment is necessary mainly due to a difference in polarity between the hydrophilic coating and the polymer device, factor which hinder the adhesion between them. The surface treatment of 7 polymeric devices can be accomplished by various methods ranging from wet to dry processes such as controlled oxidation using oxyacids6–8 , plasma9–12 and flame treatments13. Generally, techniques for surface modification are used to introduce polar functional groups that promote interaction at the interface between the device and polymer coating through intermolecular interactions, improving the wettability of the device3,8,12,14 . This study investigated the use of oxygen plasma, hydrogen peroxide solution and flame exposure treatments to provide hydrophilicity to polyamide 11 (PA11) catheter surfaces. In particularly, the influence of exposure 64 times for each individual technique was evaluated with the aim of increasing the adhesion between the PA11 catheter and the hydrophilic coating. The wettability and adhesion of a hydrophilic coating were investigated. Treated samples were characterized by goniometry, scanning electron microscopy, infrared spectroscopy and scratch resistance of the hydrophilic coating deposited.