PATOJENİK BAKTERİLERİN TANISI İÇİN NANOESASLI SENSOR PLATFORMLARI

Abstract

In the first part of this study, chitosan-graft-PCL (CS-g-PCL) copolymers and PCL polymer were synthesized. For grafting of PCL oligomers on the chitosan chains, chitosan was dissolved in acidic solvent (Methane sulfonic acid) under N2 atmosphere, then ε-caprolactone monomers was added to the solution. Grafting reaction initiated in acidic condition and ended after 5 hours. In this part two different CS-g-PCL copolymers with different proportion of chitosan and ε-caprolactone were synthesized. Synthesizing of PCL polymer was carried out by use of the ring opening polymerization. ε-caprolactone in pyrex tube heated up to 110 ̊C under N2 atmosphere, after that Sn(Oct)2 was added as catalyzer and put in oven at 120 ̊C for 24 hours. Synthesized copolymers and PCL were characterized with FTIR, 1HNMR, GPC and TGA. Results of characterization described that the synthesize procedures were done successfully. Molecular weights of copolymers and PCL were obtained. Then, different blends of PCL with each of the copolymers were prepared in the chloroform and N,N-dimethylformamide as a solvent system. PCL and Blend solutions were used to prepare nanofibers with electrospinning. Two different types of electrospinning system were used to prepare nanofibers. In the first part, conventional electrospinning system with syringe and rotating collector was used to produce nanofibers. In the second part, nanospider electrospinning machine produced with Elmarco Co. was used for electrospinning process. Surface chemistry, hydrophilic and hydrophobic character and mechanic strength of nanofiber matrices were characterized with XPS (X-ray Photoelectron Spectroscopy), water contact angle and mechanic tests respectively. Antibacterial activity of the nanofiber matrices were studied with use of two different bacteria as gram positive and gram negative bacteria. Also the formation of biofilm on the surface of nanofiber matrices was studied. Sonochemical reduction method was used for reduction of gold and silver nanoparticles on the surface of the nanofiber matrices, and for comparison, deposition of synthesized gold nanoparticles on the surface of the nanofiber matrices with use of sonication was done in parallel with sonochemical reduction procedure. SEM image of prepared nanofiber matrices and nanofibers doped with gold and silver particles, were obtained and showed successful preparation of matrices. Raman spectroscopy was used to study the surface enhanced (SERS) properties of doped gold and silver nanoparticles on the surface of nanofiber matrices. Then the effect of nanofiber matrices with highest SERS peaks on gram negative bacteria (E. coli ATCC 25922) studied with fluorescence microscope.