Thiomers: A new generation of mucoadhesive polymers

Bernkop‐Schnürch, Andreas

doi:10.1016/j.addr.2005.07.002

Cited by 550 publications

(286 citation statements)

References 47 publications

Supporting

Mentioning

281

Contrasting

Unclassified

Order By: Relevance

“…Viscosity of TH5 shows 2.92 fold increase over xyloglucan. It occurs because of the formation of disulfide bonds within the threedimensional polymeric network leads to an increased viscosity (Bernkop-Schnürch 2005). …”

Section: Viscosity Measurementmentioning

confidence: 99%

Synthesis and characterization of a cysteine xyloglucan conjugate as mucoadhesive polymer

Bhalekar¹,

Sonawane

Shimpi³

2013

Braz. J. Pharm. Sci.

View full text Add to dashboard Cite

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.

show abstract

Section: Viscosity Measurementmentioning

confidence: 99%

Synthesis and characterization of a cysteine xyloglucan conjugate as mucoadhesive polymer

Bhalekar¹,

Sonawane

Shimpi³

2013

Braz. J. Pharm. Sci.

View full text Add to dashboard Cite

show abstract

“…As an example, the accumulation of glutathione in the cytosol is worth mentioning. 179 Therefore, delivery vehicles based on functional groups cleavable in the presence of high reducing agents concentrations are particularly attractive for intracellular delivery. 180 In this context, the utilization of crosslinking molecules containing disulfide bonds hydrolysable in the presence of reducing agents have gained increasing interest for the preparation of degradable microgels.…”

Section: Microgels Containing Hydrolytically Cleavable Crosslinkersmentioning

confidence: 99%

Light-Sensitive Polymeric Nanoparticles Based on Photo-Cleavable Chromophores

Klinger

2013

Springer Theses

View full text Add to dashboard Cite

This thesis focuses on the design, synthesis and characterization of novel photo-sensitive microgels and nanoparticles as potential materials for the loading and light-triggered release/accessibility of functional compounds. In order to realize this concept, different approaches to irradiation-dependent response mechanisms have been investigated.Novel light-cleavable divinyl functionalized monomeric crosslinkers based on o-nitrobenzyl derivatives were synthesized and used for the preparation of either PMMA or hydroxyl functionalized PHEMA microgels swellable and degradable in organic solvents. By the introduction of anionic MAA moieties into the PHEMA microgels, this concept was successfully transferred to double stimuli-responsive p(HEMA-co-MAA) hydrogel nanoparticles exhibiting a pH-dependent swelling and light-induced degradation behavior in aqueous media. This sensitivity to two orthogonal triggers is proposed to combine a pHinduced post-formation loading mechanism with a pH-and light-triggered release. In addition, a new class of enzyme-and light-sensitive PAAm microgels based on (meth-)acrylate functionalized dextrans as photo-and enzymatically degradable macromolecular crosslinkers was developed by introducing a photo-labile linker between the enzymatically degradable dextran chain and the polymerizable vinyl moieties. Here, the water solubility of the crosslinkers is assumed to enable an in situ loading approach of hydrophilic compounds.A different approach to the loading of microgels is based on photo-labile covalent microgel-drug conjugates. The first step to the realization of this concept was achieved by the development of a novel functional monomer consisting of a doxorubicin molecule covalently attached to a radically polymerizable methacrylate group via a photo-cleavable linker.Moreover, in order to enable the release of hydrophobic substances in aqueous media, hydrophobic nanoparticles consisting of a photo-resist polymer were designed to be degradable upon irradiation in water. Light-triggered conversion of the initial hydrophobic polymer into hydrophilic PMAA induced in situ particle dissolution and release of nile red.Since the introduction of a stimuli-responsive shell around a microgel is assumed to prevent leakage of embedded compounds, studies on non-stimuli-responsive shell formation around preformed microgel seed particles and the formation of microgel cores in polymeric shells were conducted to investigate potential synthetic pathways to this approach.In a last attempt, the surface of PHEMA and p(HEMA-co-MAA) microgels was functionalized with cinnamoyl groups in order to trigger the (reversible) particles interaction with each other by light-induced [2+2] cycloaddition reactions.

show abstract

“…Thiolation reaction with Traut's reagent (2-iminothiolane) has the advantages of being a one-step reaction and protecting the thiolating agent from oxidation. The degree of thiol substitution in thiolated chitosan can be obtained based on Ellman's method for assaying thiols [33][34][35][36][37][38][39][40][41][42][43]. Thiolated chitosan possesses better mucoadhesiveness and permeation properties as compared to unmodified chitosan [33][34][35][36][37][38][39][40][41][42][43].…”

Section: Thiolationmentioning

confidence: 99%

“…Nanoparticles of thiolated chitosan may be obtained as a result of an ionic cross-linking reaction of thiolated chitosan with TPP [100]. Thiolated chitosan nanoparticles have been studied for applications in drug delivery as well as for permeation enhancement [33][34][35][36][37][38][39][40][41][42][43].…”

Section: Thiolationmentioning

confidence: 99%

“…Thus, in the current chapter, an overview on the drug delivery applications of cross-linked [23] and chemically modified chitosan is given. Important modified and cross-linked derivatives include carboxymethyl-chitosan (CMC), O-carboxymethyl-chitosan (O-CMC), N,O-carboxymethyl-chitosan (N,O-CMC) and N-carboxymethyl-chitosan (N-CMC) [14][15][16][17][18][19], succinylchitosan [24][25][26][27][28][29][30][31][32], thiolated chitosan [33][34][35][36][37][38][39][40][41][42][43], and chitosan grafted with PNIPAAm and PNVCL (chitosang-PNIPAAm and chitosan-g-PNVCL) [44][45][46][47].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation