Grafting ofchitosan with fatty acyl derivatives

Abstract

A plastificação interna da quitosana pela inserção covalente de longas ramificações alifáticas, tipicamente 12C, foi conduzida por meio da reação de condensação entre os grupamentos amino da quitosana com os derivados ácidos do ácido láurico, como anidrido ou cloreto de lauroíla que são mais reativos do que o ácido correspondente. A rota química possibilitou a N-acilação seletivamente. O grau de substituição, determinado quatitativamente por FTIR e 1 H NMR, variou entre 3 e 35%. A análise quantitativa por FTIR baseou-se em um método de calibração que forneceu boa precisão nos resultados. A quitosana modificada mostrou-se solúvel em água neutra e/ou DMF conforme o grau de substituição.The internal plasticization of chitosan with covalently linked long aliphatic branches, typically 12C, was accomplished through the condensation of the amino groups of chitosan with acidic derivatives of lauric acid, as lauroyl anhydride or lauroyl chloride, that are more reactive than the fatty acid itself. The chemical pathway led to selective N-acylation. The degree of substitution was quantitatively determined by FTIR and 1 H NMR and varied between 3 and 35%. The FTIR quantitative analysis was based in a calibration mmethod with good accuracy. The modified chitosan products were soluble in neutral water and/or DMF according to the degree of substitution. The modified chitosan films were more flexible than the pristine, non-modified ones.

One-Step Biofunctionalization of Quantum Dots with Chitosan and N-palmitoyl Chitosan for Potential Biomedical Applications

“…N -acylation of chitosan is favored compared to O -acylation because amines are more nucleophilic than hydroxyls (carbons 3 and 6 of the chitosan chain). Also amides are more stable molecules due to the effect of resonance localization of the lone pair electrons on nitrogen into the carbonyl “π” system [47]. That means, the presence of nucleophilic sites in the chitosan polymer was not significantly altered by grafting the N -palmitoyl moieties, leading to the formation of the lipid glycoconjugate (C-Pal).…”

Functionalized chitosan derivatives as nonviral vectors: physicochemical properties of acylated N,N,N-trimethyl chitosan/oligonucleotide nanopolyplexes

“…Notably, a DS value ranging from 1% to 10% was expected for the acylation of TMC based on the reaction conditions using buffered solutions at approximately neutral pH (pH 7.4, slightly above the pK a 6.5 of chitosan), as was used in our experiments, where N-acylation (primary amine groups) was preferred over O-acylation (C3 and C6 alcohol groups) of TMC. 24,39 Moreover, taking into account the relatively high degree of quaternization of TMC (approximately 30%), calculated as previously described 31 based on the 1 H NMR spectrum of TMC (Fig. 1A and Fig.…”

“…The CAC of fatty acid-modified TMCs was measured using pyrene (Synergy Mx, BioTek Instruments, USA), which acts as a hydrophobic probe in fluorescence spectroscopy. [33][34][35][36][37][38][39] For CAC experiments, TMC derivative solutions were prepared in 20 mM HEPES buffer containing 5 w/v% glucose (pH 7.4). A specific volume of pyrene aqueous solution (the final concentration of pyrene was controlled at 60 mM) was added under vortexing (3 s) and heated overnight to equilibrate the aggregates.…”

Encapsulation of salicylic acid in acylated low molecular weight chitosan for sustained release topical application

“…The absorption peak at 1570 cm −1 attributed to bending of primary amino group at C2 of chitosan in LMWC was disappeared and substituted with 1558 cm −1 which corresponded to NH bending of amide II (in combination with CN stretching) in LMWC‐B . The absence of absorption peak above 1700 cm −1 characterized for O ‐acyl ester chitosan in the spectrum revealed there was no O ‐acylation occurred on the LMWC in the reaction . All these observations showed the successful N ‐acylation of butyric anhydride onto the LMWC.…”

“…47,48 The absence of absorption peak above 1700 cm 21 characterized for O-acyl ester chitosan in the spectrum revealed there was no Oacylation occurred on the LMWC in the reaction. 49 All these observations showed the successful N-acylation of butyric anhydride onto the LMWC. FTIR spectrum is useful to show the effect of the acylating agent on DB via peak intensity at certain wavelength number.…”