Characterization of well‐defined poly(ethylene glycol) hydrogels prepared by thiol‐ene chemistry

Yang, Ting; Long, Hai; Malkoch, Michael; Gamstedt, E. Kristofer; Berglund, Lars A.; Hult, Anders

doi:10.1002/pola.24847

Cited by 60 publications

(66 citation statements)

References 33 publications

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“…28–31 Having established the pH-responsiveness of DEGE-containing materials, we set out to explore the use of poly( N,N -diisopropyl ethanolamine glycidyl ether) (PDEGE) domains as the responsive element within the context of pH-triggered hydrogelation from symmetric PDEGE- b -PEO- b -PDEGE triblock copolymers. A symmetric DEGE-containing triblock copolymer was synthesized using a 20 kg mol −1 PEO-diol as a macroinitiator as shown in Scheme 2.…”

Section: Resultsmentioning

confidence: 99%

Physiologically relevant, pH-responsive PEG-based block and statistical copolymers with N,N-diisopropylamine units

et al. 2013

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In order to impart pH-responsiveness within a physiologically-relevant context to PEG-based biomaterials, a new tertiary amine containing repeat unit, N,N-diisopropyl ethanolamine glycidyl ether (DEGE), was developed and incorporated into statistical and block copolymers with ethylene oxide (EO), and allyl glycidyl ether (AGE) via anionic ring-opening polymerization. The reactivity of this novel monomeric building block in copolymerizations with EO was investigated by spectroscopy with observed reactivity ratios of rDEGE = 1.28 ± 0.14 and rEO = 0.82 ± 0.10. It was further demonstrated that DEGE containing copolymers could serve as building blocks for the formation of new pH-responsive materials with a pKa of ca. 9, which allowed macroscopic hydrogels to be prepared from symmetric triblock copolymers PDEGE5.3k-b-PEO20k-b-PDEGE5.3k. The triblock copolymers exhibited clear sol-to-gel transitions in a physiologically-relevant critical gelation range of pH 5.8–6.6 and pH-dependent viscoelastic properties. On the nanometer scale, the preparation of pH-responsive micro- or nanogels was demonstrated by crosslinking P(DEGE-co-AGE) copolymers in miniemulsion droplets stabilized by PEO-b-P(DEGE-co-AGE) diblock terpolymers. These nanoparticles exhibited a reversible pH-dependent swelling profile with a volume phase transition at physiological pH 6.5–7.5.

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Section: Resultsmentioning

confidence: 99%

Physiologically relevant, pH-responsive PEG-based block and statistical copolymers with N,N-diisopropylamine units

et al. 2013

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“…15 Both the S2 and S8 were immersed in distilled water for 5 h and in ethanol (100%) for 3 h to remove any remaining residues. The purified hydrogels were air dried overnight and placed in a vacuum oven at 40 C for 1 h to remove any remaining solvents.…”

Section: Preparation Of Seqipns Hydrogelsmentioning

confidence: 99%

“…[12][13][14] In the case of hydrogels, PEG with chain lengths ranging between 2 kDa and 8 kDa has successfully been constructed within 5 min at ambient conditions via the UV initiated TEC reaction. 15,16 The mechanical properties of these gels depend on several parameters of which the chain length and type of the chain-ends on the PEG precursors, that is, being a thiol (PEG-SH) or unsaturated allyl group (PEG-allyl), are of importance. For example, the elastic modules was found to be three times larger for a hydrogel based on 3 kDa PEG allyl (E ¼ 311 kPa) when compared with a hydrogel prepared from 3 kDa PEG-thiol (E ¼ 139 kPa).…”

mentioning

confidence: 99%

The influence of diffusion time on the properties of sequential interpenetrating PEG hydrogels

Yang¹,

Malkoch²,

Hult³

2012

J. Polym. Sci. A Polym. Chem.

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Four sets comprising a total of 16 sequential interpenetrating network (SeqIPN) hydrogels were efficiently fabricated via UV initiated thiol-ene coupling chemistry and from 2 kDa or 8 kDa primary poly(ethylene glycol) (PEG) networks (S2 and S8). Each primary system delivered four different SeqIPNs constructed after 2, 4, 20, and 44 h diffusion of secondary network PEG precursors, 2 kDa and 8 kDa. This allowed the assessment of both mechanical and swelling properties for a wide range of novel hydrogels ranging from loosely crosslinked SeqIPN 8-8 to densely crosslinked SeqIPN 2-2 systems. All gel fractions of secondary networks were above 83% and 44 h of diffusion was found sufficient to fully saturate the primary networks. Disperse red functionalized PEGs (2 kDa and 8 kDa) were further used as probes to investigate the diffusion mechanisms. The impact of diffusion time on loosely crosslinked S8 network with a swelling degree of 970% and tensile modulus of 175 kPa displayed a significant change in the final properties. For instance, a 2 h diffusion of 2 kDa PEG precursors generated a SeqIPN 8-2:2 comprising a secondary network solid content of 34% with a water swelling degree 580% and a tensile modulus of 365 kPa. On saturation, that is, 44 h of diffusion, SeqIPN 2-8:44 exhibited 64% of secondary network solid content, a swelling capacity of 380% and over fourfold of tensile modulus (758 kPa) when compared with the primary network S8. SeqIPN hydrogel with the highest tensile modulus and lowest degree of water swelling was obtained after 44 h diffusion of 2 kDa PEG precursors within the densely crosslinked S2 primary network. In this case, SeqIPN 2-2:44 noted a water swelling capability of 280% and a tensile modulus over 1 MPa. The latter was twofold when compared with S2 with a tensile modulus of 555 kPa. Consequently, the diffusion time of secondary network is a promising parameter to control and that enables the fabrication of PEG hydrogels with a wider window of mechanical and swelling properties.

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“…Rapid rates under mild conditions and control of when and where they take place with light make these reactions well-suited for user-directed control of biomaterial properties in the presence of cells. 7,8 In particular, thiol−ene photoclick chemistries have been used to generate hydrogel-based biomaterials with robust mechanical properties 5,9 and for the encapsulation of a wide variety of cell types, including, but not limited to, human mesenchymal stem cells (hMSCs), fibroblasts, chondrocytes, and pancreatic cells, with promise for cell culture and delivery. 10,11 Further, these chemistries have been used for the spatial patterning of biochemical cues to mimic key aspects of native cell microenvironments and facilitate appropriate cell-matrix interactions, including adhesion, differentiation, and invasion.…”

Section: Introductionmentioning

confidence: 99%

Light-mediated Formation and Patterning of Hydrogels for Cell Culture Applications

Sawicki

Kloxin

2016

JoVE

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Click chemistries have been investigated for use in numerous biomaterials applications, including drug delivery, tissue engineering, and cell culture. In particular, light-mediated click reactions, such as photoinitiated thiol−ene and thiol−yne reactions, afford spatiotemporal control over material properties and allow the design of systems with a high degree of user-directed property control. Fabrication and modification of hydrogel-based biomaterials using the precision afforded by light and the versatility offered by these thiol−X photoclick chemistries are of growing interest, particularly for the culture of cells within well-defined, biomimetic microenvironments. Here, we describe methods for the photoencapsulation of cells and subsequent photopatterning of biochemical cues within hydrogel matrices using versatile and modular building blocks polymerized by a thiol−ene photoclick reaction. Specifically, an approach is presented for constructing hydrogels from allyloxycarbonyl (Alloc)-functionalized peptide crosslinks and pendant peptide moieties and thiol-functionalized poly(ethylene glycol) (PEG) that rapidly polymerize in the presence of lithium acylphosphinate photoinitiator and cytocompatible doses of long wavelength ultraviolet (UV) light. Facile techniques to visualize photopatterning and quantify the concentration of peptides added are described. Additionally, methods are established for encapsulating cells, specifically human mesenchymal stem cells, and determining their viability and activity. While the formation and initial patterning of thiol-alloc hydrogels are shown here, these techniques broadly may be applied to a number of other light and radical-initiated material systems (e.g., thiol-norbornene, thiol-acrylate) to generate patterned substrates.

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Characterization of well‐defined poly(ethylene glycol) hydrogels prepared by thiol‐ene chemistry

Cited by 60 publications

References 33 publications

Physiologically relevant, pH-responsive PEG-based block and statistical copolymers with N,N-diisopropylamine units

Physiologically relevant, pH-responsive PEG-based block and statistical copolymers with N,N-diisopropylamine units

The influence of diffusion time on the properties of sequential interpenetrating PEG hydrogels

Light-mediated Formation and Patterning of Hydrogels for Cell Culture Applications

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