The Amphipathy Of Chitosan Derivatives And Its Interaction With Histamine On Air-water Interface

In this work, three amphiphilic chitosan derivatives, stearyl chitosan ?SCTS?, had been synthesized from chitosan and stearyl chloride by the selective protection of amino groups in MeSO3H, and then was characterized by means of FT-IR,1H NMR, XRD, contact angle and GPC. The amphiphilic properties and Langmuir monolayer behavior of SCTS were investigated on air-water interface. The ?-A isotherms revealed that the formation of amphiphilic SCTS monolayer with A*=150.5 cm² and the collapse pressure= 59.53 mN/m. The compression performance and relaxation phenomena of the resultant monolayer were observed by ?d?/dA?-A curve and cyclic compression-decompression curves, respectively. Moreover, the effect of conditions in sbuphase on the monolayer behavior was described. After changing the phase composition, the ?-A isothermal curves of the SCTS monolayer could change accordingly. The results showed that the SCTS monolayer had a strong and stable amphiphilic property in the subphase with pH=6.5, the monolayer stability weakened relatively in the acidic or weak alkaline subphase ?pH=3.0,5.0 and 9.0? and the monolayer could not formed in the subphase with strong base ?pH=12.0?. In addition, the SCTS monolayer properties were affected the addition of copper ion and its concentration. The A* and collapse pressure for the monolayer increased and reduced in the subphase with copper ion. The increment of A* decreased with the increase of amount of copper ion.Histamine is the one of widely distributed and bioactive substances in the human body tissue cells histamine. The Langmuir film of the chitosan derivative containing histamine was formed via reconstruction induced by histamine on air-water interface. And the interaction between stearyl chitosan and histamine in the two-component monolayer was explored. The two-conponent monolayer possessed an A* of 205.6 cm² and single collapse pressure of 31.62 mN/m, indicating a good miscibility between two components when the addition of 100 ?L of histamine solution at concentration of 0.2 mol/mL. The A* and collapse pressure of the two-component monolayer increased to 248.8 cm² and 60.10 mN/m when the 250 ?L of histamine was added in the subphase, showing that more histamine molecules were adsorbed SCTS monolayer. Also, the enhanced capability of SCTS monolayer adsorption for histamine created improved the stability and strength of the mixed membrance. In addition, besides histamine amount, the subphase environment (pH and Cu²⁺) had influence on the condensed SCTS-histamine monolayer behaviour. The A* increased to 286.3 cm² when the addition of Cu²⁺ in the subphase with pH of 8.5 and displayed a single collapse pressure of 52.65 mN/m.SCTS monolayer transferability was very good from deposition curve of LB. AFM images of SCTS and SCTS-histamine mixed LB membranes were compared and showed that the presence of small aggregates ?0.968 nm average roughness? with a root-mean-square ?rms? roughness of 1.614 nm, and for the SCTS single monolayer these two values were 1.354 and 1.847 nm.