טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentRozen Yoav
SubjectStudying Medical Sealant Based on Alginate and Phenol
DepartmentDepartment of Chemical Engineering
Supervisor Professor Havazelet Bianco-Peled
Full Thesis textFull thesis text - English Version


Abstract

Over leakage of body fluids is a major factor that complicates clinical procedures. In bypass surgeries, for example, blood vessels are reattached to replace damaged ones in order to restore an intact blood supply. Bleeding during these procedures is a major obstacle, especially in light of the use of systemic anticoagulation agents. The use of an adhesive agent that actively forms barrier which stops leakage offers a good alternative to traditional hemostatic methods such as suture and/or topical hemostatic agents.

The current research focuses on a surgical adhesive composed of cross-linked alginate and phloroglucinol. This formulation was previously shown to glue wet and dry surfaces. The purpose of this research was to evaluate the capability of the adhesive to function as a tissue sealant and to characterize its properties and mechanism of action.

A new apparatus was developed especially for this research in order to characterize the sealing performance. As opposed to the commonly used characterization methods, this method measures the actual sealing capability of the adhesive by measuring the burst pressure, namely the pressure in which the sealant fails to seal a hole when exposed to pressure.

Optimization had shown that the sealant best performance was obtained with phloroglucinol concentration between 5 to 10 mg/ml and alginate concentration of 35 mg/ml. Altering the alginat's molecular weight did not change this optimum.

The replacement of Phloroglucinol with other phenols resulted with a phenol type dependence of the burst pressure. It was suggested that hydroxyl group which are symmetrically arranged on the benzene ring is a common feature of the phenols that positively contribute to the sealing performance. Large polyphenols were found to lower the sealing performance.

Rheological measurements have showed that phenol addition to alginate reduced the Ca2 concentration necessary for inducing a sol-gel transition. This finding support the assumption that interactions between the phenol and the alginate exist, however no relation was found between that phenomenon and the sealing ability. An interesting finding was the existence of a direct relation between the pre-gelled solution's viscosity and the sealing ability of the cured formulation.

Phloroglucinol was found to reduce the cohesive strength compare to gelled alginate. In addition its contribution to the sealing ability was influenced by the substrate’s hydrophilic. These two findings have led us to the assumption of the phloroglucinol interference with the sealant-substrate interactions.

The research evidences can assist with future work of seeking for medical sealants.