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Facile Synthesis of Degradable and Electrically Conductive Polysaccharide Hydrogels
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
2011 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 12, no 7, 2601-2609 p.Article in journal (Refereed) Published
Abstract [en]

Degradable and electrically conductive polysaccharide hydrogels (DECPHs) have been synthesized by functionalizing polysaccharide with conductive aniline oligomers. DECPHs based on chitosan (CS), aniline tetramer (AT), and glutaraldehyde were obtained by a facile one-pot reaction by using the amine group of CS and AT under mild conditions, which avoids the multistep reactions and tedious purification involved in the synthesis of degradable conductive hydrogels in our previous work. Interestingly, these one-pot hydrogels possess good film-forming properties, electrical conductivity, and a pH-sensitive swelling behavior. The chemical structure and morphology before and after swelling of the hydrogels were verified by FT-IR, NMR, and SEM. The conductivity of the hydrogels was tuned by adjusting the content of AT. The swelling ratio of the hydrogels was altered by the content of tetraaniline and crosslinker. The hydrogels underwent slow degradation in a buffer solution. The hydrogels obtained by this facile approach provide new possibilities in biomedical applications, for example, biodegradable conductive hydrogels, films, and scaffolds for cardiovascular tissue engineering and controlled drug delivery.

Place, publisher, year, edition, pages
2011. Vol. 12, no 7, 2601-2609 p.
National Category
Materials Engineering
URN: urn:nbn:se:kth:diva-37165DOI: 10.1021/bm200389tISI: 000292617700021ScopusID: 2-s2.0-79960227637OAI: diva2:432318
Available from: 2011-08-02 Created: 2011-08-02 Last updated: 2011-11-23Bibliographically approved
In thesis
1. degradable electroactive polymers: Synthesis, Macromolecular architecture and scaffold design
Open this publication in new window or tab >>degradable electroactive polymers: Synthesis, Macromolecular architecture and scaffold design
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Electrically conducting polymers induce specific cellular responses at the molecular level. One of the crucial limitations of the use of conducting polymers in tissue engineering is their inability to degrade. The incorporation of conductivity into degradable polymers to obtain materials that are both electroactive and degradable is therefore highly anticipated. Architecture plays an important role in the performance of polymers. To be able to achieve the optimal mechanical, degradation, thermal and biological properties for a particular biomedical application, it is desirable to promote architectural diversity.

 In the first part, by combining the electroactivity of conducting polymers and the degradability of aliphatic polyesters, we have designed and synthesized a series of linear, star-shaped, hyperbranched, and crosslinked degradable and electrically conducting polymers and hydrogels based on polylactide (PLA), polycaprolactone (PCL), and aniline oligomers such as aniline trimer, aniline tetramer, and aniline pentamer. The polymers and hydrogels obtained have good electroactivity, as indicated by their ultraviolet spectra and by cyclic voltammetry. The conductivities of the polymers and hydrogels are tuned by the content of the aniline oligomer and the macromolecular architecture. The hydrophilicity of the polymers was greatly increased after doping the aniline oligomer with acid, which overcomes the hydrophobicity of the PLA and PCL. Thermogravimetric analysis and differential scanning calorimetry studies show that these copolymers and hydrogels have good thermal properties compared to PLA and PCL. The swelling ratios of these hydrogels covered a wide range and were controlled by the degree of crosslinking, the oligoaniline content, and the pH of the surrounding solution.

 In the next part, methods for the facile synthesis of degradable conducting polymers and hydrogels were presented to avoid the multi-step reaction used in the earlier work. We developed a one-pot reaction for the synthesis of degradable conducting polysaccharide hydrogels based on chitosan and aniline tetramer. These hydrogels can form free-standing and flexible conducting films. This overcomes the drawback of polyaniline which could not be easily fabricated into a thin film in common organic solvents. We also presented a universal two-step approach to create degradable conductive diblock or triblock copolymers based on a polyester and aniline tetramer or aniline pentamer by a combination of ring opening polymerization and post-functionalization via an oxidative coupling reaction. The self-assembly behavior of the triblock copolymer consisting of a middle aniline pentamer segment and two bilateral polycaprolactone segments in chloroform as a selective solvent (selective for PCL segment) were also investigated by transmission electron microscopy and dynamic light scattering. The size of the nanoparticles from the assembly of the triblock copolymers depends on the molecular weight of the copolymer and on the aniline pentamer state.

 In the last part, electroactive degradable non-toxic porous tubular scaffolds were fabricated from a polymer blend of hyperbranched degradable conductive copolymer and PCL by a modified solution-casting/particle-leaching technique. The porous structure of the tubular scaffolds was investigated by scanning electron microscope and microcomputed tomography. The hydrophilicity of the blend films was greatly improved by doping with (±)-10-camphorsulfonic acid. The conductivity of the films was tuned by adjusting the ratio of hyperbranched degradable conducting copolymer to PCL. The cytotoxicity test with HaCaT keratinocytes indicated that the materials were non-toxic.

 These degradable electroactive copolymers and hydrogels with different architectures and properties have a great potential for meeting the requirements of biomedical application.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. 87 p.
Trita-CHE-Report, ISSN 1654-1081 ; 2011:55
Poly(lactide), poly(ε-caprolactone), ring-opening polymerization, carboxyl-capped aniline trimer, carboxyl-capped aniline pentamer, phenyl amino-capped aniline tetramer, coupling reaction, DCC/DMAP system, degradability, electroactivity, conductivity, macromolecular architecture, chitosan, hydrogel, block copolymer, functionalization, oxidative coupling reaction, self-assembly, toxicity, tubular porous scaffold, neural tissue engineering.
National Category
Engineering and Technology
urn:nbn:se:kth:diva-48171 (URN)978-91-7501-136-3 (ISBN)
Public defence
2011-12-07, F3, Lindstedsvägen 26, KTH,, Stockholm, 10:00 (English)
QC 20111123Available from: 2011-11-23 Created: 2011-11-16 Last updated: 2011-11-23Bibliographically approved

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