Desenvolvimento e caracterização termomecânica de adesivos de tecido a base de cianoacrilato

Abstract

Tissue adhesives are important elements in modern medicine and assist in the healing process of traumatic lacerations and surgical incisions of the human skin in a natural manner providing less tissue trauma. They are easy to use, dismiss the necessity of sutures, provide good cosmetic outcomes, and can provide local controlled drug release. They have been used to stop bleedings and hemorrhagic in vascular systems and act as a microbial barrier and structural fixation agents. The aim of this work was to specify the chemical composition of tissue adhesive based on cyanoacrylate-based blends. The characterization of three different formulations was achieved through FTIR (Frontier, Perkin Elmer), TGA (TGA 50, Shimadzu), DSC (DSC Q 20, TA Instruments). FTIR spectra obtained between 200 cm-1 and 4000 cm- 1 indicated the presence of specific functional groups, the base monomers of the formulas. TGA and DSC provided information on the thermal profile of the formulas showing the degradation profile and the temperature of mass loss. The samples started to degrade around 160°C and were completely degraded between 200 and 250 °C. Nonetheless, viscosity measures (DHR3, TA Instruments) provided information about the viscosity of the formulas and their behavior upon a temperature change and shear rate change. The shear rate range was from 300 s-1 to 1 s-1, while the temperature varied between 20°C and 37°C. DMTA (DMA Q8000, TA Instruments) and oscillatory rheology (DHR-3, TA Instruments) showed the difference in the properties and in the material’s behavior, as well as the transition between elastic and viscous behavior. Mechanical characterization was achieved through comparison between these results and the correspondent results of mechanical testing as per ASTM standards applicable to tissue adhesives. Specifically, for DMTA, compositions showed similar storage and loss modulus under a temperature range of 0-80°C, while a commercial standard sample, which was utilized as a comparison standard, showed the lowest values, about 25% less than other samples. Oscillatory rheology performed under 37°C with a change in the deformation amplitude between 0 and 100% and a constant oscillation frequency 5 rad/s, allowed a comparison between the samples evaluated and with the results from DMTA testing. ASTM testing results suggests the utilization of a viscous n-butyl and 2-octyl cyanoacrylate-based blend só that there is no compromise in the mechanical properties of the adhesive, but providing a better degree of biocompatibility, as the literature shows. Even though, biological testing is out of the cope of this study, comparisons between the mechanical properties of each sample and their respective biological response gives rise to a favorable scenario, as reported in the literature.