Synthesis and characterization of a cysteine xyloglucan conjugate as mucoadhesive polymer

Abstract

The aim of this study was to improve the mucoadhesive potential of xyloglucan polymer by the covalent attachment of cysteine as thiol moiety. The parent polymer xyloglucan was chemically modified by introducing sulphydryl bearing compound L-cysteine HCl. Different batches of xyloglucan-cysteine conjugates were prepared at varying reaction pH (2-6) and evaluated for optimum thiol incorporation, disulphide group content, swelling behavior, rheological properties and mucoadhesive properties. The obtained conjugates characterized in vitro by quantification of immobilized thiol groups; showed maximum thiol incorporation on xyloglucan (7.67 ± 0.14 %) at pH 5. The disulphide group content was found maximum (2.83 ± 0.12) at pH 6. The water uptake at end of 4 h was 5.0 for xyloglucan and was found to decrease in thiolated derivatives with increase in thiolation. Mucoadhesion studies revealed that mucoadhesion of xyloglucan-cysteine conjugate increased more than twice compared to the unmodified polymer. The viscosity of thiomer was more than that of xyloglucan because of formation of disulphide bonds.Uniterms: Mucoadhesion. Thiomer. Xyloglucan. L-cysteine HCl.O objetivo deste estudo foi melhorar o potencial mucoadesivo do polímero xiloglicano pela ligação covalente de cisteína como unidade de tiol. O polímero xiloglicano foi quimicamente modificado pela introdução de cloridrato de cisteína como grupo contendo sulfidrila. Prepararam-se diferentes lotes de conjugados cisteína-xiloglicano em pH variando de 2 a 6, avaliando-se a incorporação ótima de tiol, o conteúdo de dissulfeto, o comportamento de inchamento, as propriedades reológicas e mucoadesivas. Os conjugados obtidos foram caracterizados in vitro pela quantificação de grupos tiol, mostrando máxima incorporação na xiloglicana (7.67 ± 0.14 %) em pH 5. O conteúdo de grupos dissulfeto foi máximo (2.83 ± 0.12) em pH 6. O índice de inchamento em % no fim de 4 h foi 83.87 para o xiloglicano e diminuiu para os derivados tiolados. O conteúdo foi mínimo para TH2 (78.26), aumentou pouco até TH5 (83.33) e diminuiu, posteriormente, para TH6 (80.13). Os estudos de mucoadesão revelaram que o conjugado xiloglicano-cisteína aumentou mais que duas vezes comparativamente ao polímero não modificado. A viscosidade do tiômero foi maior do que a do xiloglicano devido à formação das ligações dissulfeto.

Self-healing of Poly(2-hydroxyethyl methacrylate) Hydrogel through Molecular Diffusion

“…Therefore, once polymerization completed, spectrum for C=C at 1637cm -1 (Figure 1(a)) will disappear as shown in the ATR spectra (Figure 1(c)). Besides, the second possible reaction is condensation process between hydroxyl group of the HEMA with carboxylic acid of the cystine forming ester bond which it is in agreement with the previous study reported (Bhalekar et al 2013). In addition, the elements for breaking and reformation of disulphide bond on the hydrogel for thermally healing system will be explored in the future.…”

Effect of cross-link density and the healing efficiency of self-healing poly(2-hydroxyethyl methacrylate) hydrogel

“…l-Cystine acted as a cross-linker by the condensation reaction of its carboxyl groups with the hydroxyl groups of the HEMA, forming ester bonds, which is in agreement with the result of a previous study (11). However, future work needs to be done for further confirmation of the ester bond from the cross-linking reaction and for comparison between poly(HEMA) with and poly(HEMA) without a cross-linker.…”

Development of a Novel Equilibrium Passive Sampling Device for Methylmercury in Sediment and Soil Porewaters

“…Agarose gels were prepared with an existing method (Gao et al ), but suspensions of sorbents in agarose were based on custom formulations. Sulfur‐functionalized polymers were identified in the biomedical (Bernkop‐Schnürch et al ; Duan and Lewis ; Bhalekar et al ) or water treatment (Yu et al ) literature. A method for embedding AC in a polyvinylidene fluoride (PVDF) polymer was adapted from an electrochemistry application (Choi ).…”

“…References or sources for polymers and sorbents: ag, Gao et al (); Cys+alg, Bernkop‐Schnürch et al (); Cys+xylo, Bhalekar et al (); ag+MAA‐chit, Kast and Bernkop‐Schnürch (2001); ag+MPTMS‐DE, Yu et al (); SAMMS, Steward Environmental Solutions; agPEG, Charlionet et al (1996); CA, Membrane Filtration Products; MA, Aoki et al (2007); CN, Membrane Filtration Products; DE, Honeywell; MPTMS‐DE, Yu et al (); parafilm, Bemis; PDMS, Altec; PES, Goodfellow Cambridge; PET+Cys, Duan and Lewis (); POM38, CS Hyde; PTFE, Grainger.…”