کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1384612 982411 2008 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Precise derivatization of structurally distinct chitosans with rhodamine B isothiocyanate
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
Precise derivatization of structurally distinct chitosans with rhodamine B isothiocyanate
چکیده انگلیسی

Work to date shows that structurally distinct chitosans have reacted inefficiently and unpredictably with fluorescein isothiocyanate (FITC) in an acid–methanol solvent that maintains both chitosan and fluorophore solubility. Since isothiocyanate preferentially reacts with neutral amine groups, and chitosan solubility typically depends upon a minimal degree of protonation, we tested the hypothesis that precise derivatization of chitosan with rhodamine isothiocyanate (RITC) can be achieved by controlling the reaction time and the degree of protonation. Addition of 50% v/v methanol reduced the chitosan degree of protonation in acetic acid but not HCl solutions. At various degrees of protonation, chitosan reacted inefficiently with RITC as previously observed with FITC. Nevertheless, precise derivatization was achieved by allowing the reaction to proceed overnight at a given degree of protonation (p < 0.0001, n = 18) and fixed initial fluorophore concentration. A reproducible 2% to 4% fraction of neutral amines reacted with RITC in proportion to the initial fluorophore concentration (p < 0.005). Using our optimized protocol, chitosans with different degree of deacetylation and molecular weight were derivatized to either 1% or 0.5% mol/mol RITC/chitosan-monomer with a precision of 0.1% mol/mol. The average molecular weight of fluorescent RITC-chitosan was similar to the unlabeled parent chitosan. Precise molar derivatization of structurally distinct chitosans with RITC can be achieved by controlling chitosan degree of protonation, initial fluorophore concentration, and reaction time.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Carbohydrate Polymers - Volume 72, Issue 4, 10 June 2008, Pages 616–624
نویسندگان
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