Thermoresponsive poly(2-oxazoline)s, polypeptoids, and polypeptides

Hoogenboom, Richard; Schlaad, Helmut

doi:10.1039/c6py01320a

Cited by 256 publications

(207 citation statements)

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“…These are promising materials for biomedical applications such as drug delivery systems. [3][4][5] The produced hydrogels will be used as wound patches for infected or chronic infected wounds. Therefore, so called photosensitizers shall be incorporated in the hydrogels.…”

Section: Resultsmentioning

confidence: 99%

“…[3] In the last decades, they have been intensely investigated especially as thermoresponsive materials [4] and for biomedical applications. [5] More recently, polypeptoid based hydrogels were reported.…”

Section: Figurementioning

confidence: 99%

“…[1] The first investigations using nanoparticles of PMOs have also appeared. [2][3][4] In general, such nanoparticle systems are able to release only a single active agent, although in many cases it would be advantageous to deliver a combination of different drugs, possibly sequentially in time. For example, when implantassociated drug release is concerned, delivery of an anti-inflammatory/antibacterial drug followed by an active agent to promote healing would be beneficial.…”

Section: S05-04mentioning

confidence: 99%

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Session 5: Young Scientist Forum

2017

Biomedical Engineering / Biomedizinische Technik

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IntroductionExtrusion based additive manufacturing allows printing of cells within a cell convenient hydrogel, which commonly is referred to as bioprinting. Although the stiffness of hydrogels can be tailored, hydrogels might never reach the stiffness required for bone tissue engineered constructs. We have demonstrated the extrusion of plottable calcium phosphate cements (CPC) at mild conditions (A Lode et al., J Tissue Eng Regen Med, 2014); After transformation of the precursors to hydroxyapatite (HAP), the cement showed both high cell compatibility and mechanical stiffness suitable for bone scaffolds. Herein, the CPC was co-extruded with a cell-laden hydrogel blend consisting of 3% alginate and 9% methylcellulose (Alg-MC) (Schütz et al., J Tissue Eng Regen Med, 2017) to achieve bioprinted scaffolds with macropores and increased stiffness. Materials & MethodsCPC (Velox, INNOTERE, Radebeul, Germany) and Alg-MC were prepared as described in the literature and processed with a multichannel printing system (Bioscaffolder 3.1, GeSiM, Großerkmannsdorf, Germany). Human mesenchymal stem cells (hMSC) were mixed into the Alg-MC material. Printed constructs were analysed microscopically (stereo light microscopy, SEM, cLSM, fluorescence microscopy) and by uniaxial compressive tests. Results & DiscussionBoth materials were successfully co-extruded and combined to one scaffold. The optimal conditions for CPC setting and alginate crosslinking within the biphasic scaffold were investigated. If immersed into liquids, CPC hardens but microcracks arise simultaneously which does not happen in case of setting in humidity (Akkineni et al., Acta Biomater, 2015). Herein we observed, that initial setting for 20 min is sufficient to minimize the appearance of microcracks. Furthermore, cell viability of hMSC inside non-crosslinked Alg-MC scaffold incubated in humidity up to 30 min was not changed. As a result, biphasic scaffolds after printing were incubated in humidity for 20 min, followed by crosslinking of the hydrogel and incubation in cell culture medium. At day 1 after post-processing of the biphasic scaffolds, the cell viability was significantly reduced at the interface region between the two materials; after 21 d cells migrated from the hydrogel to the CPC strands. In conclusion, a method was developed for the fabrication of biphasic scaffolds comprising CPC and a cell-laden hydrogel, as a basis for fabrication of constructs for bone and osteochondral regeneration. Hydrogels are water-swollen polymer networks that can be loaded with bioactive substances and drugs very easily. They can absorb a large amount of water and possess a high degree of flexibility. 1, 2In this study we use poly(ethyleneglycol) diacrylate hydrogels. These are promising materials for biomedical applications such as drug delivery systems. [3][4][5] The produced hydrogels will be used as wound patches for infected or chronic infected wounds. Therefore, so called photosensitizers shall be incorporated in the hydrogels. These photosensitizers can act as antimi...

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Section: Resultsmentioning

confidence: 99%

Section: Figurementioning

confidence: 99%

Section: S05-04mentioning

confidence: 99%

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Session 5: Young Scientist Forum

2017

Biomedical Engineering / Biomedizinische Technik

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“…We found that at 10% reduced side chains, the T g shifted to 313 K. Increasing the degree of reduction further to 25%, the T g decreased to 293 K. Samples with an even higher degree of reduction (≥ 40%) did not show a T g in our experimental setup, which agrees well with the observation by Hoogenboom and co-workers. As many water-soluble polymers 13 do, the water solubility of several POx [14][15][16] and PEtOx in particular shows a dependence on the temperature. Depending on the molar mass and the polymer architecture, the lower critical solution temperature of PEtOx ranges from 343 to about 370 K.…”

Section: Figure 3|mentioning

confidence: 99%

Poly(2-ethyl-2-oxazoline-co-N-propylethylene imine)s by controlled partial reduction of poly(2-ethyl-2-oxazoline)

Pfister¹,

Ringhand²,

Fetsch³

et al. 2018

Preprint

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The partial reduction of poly(2-ethyl-2-oxazoline) was investigated. A series of poly(2-ethyl-2-oxazoline-co-N-propylethylene imine)s were synthesized by direct reduction using lithium aluminum hydride or borane/dimethylsulfide (BH 3 /DMS), respectively. It is shown that the degree of reduction can be readily controlled either by the reaction time when using an excess of LiAlH 4 or by the stoichiometry of BH 3 /DMS as was demonstrated by 1 H-NMR spectroscopy. Differential scanning calorimetry revealed that the glass transition temperature of the products decreased with increasing degree of reduction up to 25% of reduction, above which no glass transition could be detected. This control over the reduction allows the tailor synthesis of partially cationic polymers, which, in combination over the hydrophilic/lipophilic balance through the side chain length allows a tight control over materials properties. Such materials may be interesting, inter alia, for biomaterials or organic electronics.

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“…21 Poly(2-alkyl-2-oxazolines) (POx) are synthetic pseudopeptides with a -(CH 2 -CH 2 -N) n -backbone (Scheme 1). [22][23][24][25] The backbone is non-chiral and the amide-group provides coplanar side-groups. In an extended chain conformation, subsequent side-groups are alternating laterally to either side of the backbone.…”

Section: Introductionmentioning

confidence: 99%

Inversion of crystallization rates in miscible block copolymers of poly(lactide)-block-poly(2-isopropyl-2-oxazoline)

et al. 2018

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a Miscible block copolymers (BCPs) are rarely studied. When one or both components of such BCPs are semi-crystalline polymers, strong effects on the crystallization behavior can be expected. We present a study of 18 miscible BCPs comprised of poly(lactide) (PLLA, semi-crystalline and PDLLA, amorphous) and poly(2-isopropyl-2-oxazoline) (PiPOx, semi-crystalline) with PiPOx volume fractions of 0.14 < ϕ PiPOx < 0.82. All BCPs exhibit a single glass transition and form a homogeneous melt. Mixing has a plasticizing effect on PiPOx and increases its crystallization rates (DSC). In contrast, the crystallization rates of PLLA are dramatically reduced, or in most cases entirely prevented. During isothermal crystallization at 130°C, the crystallization rates of the BCPs were inverted in comparison with those of the parent homopolymers. Crystallization drives the BCPs to phase separate and the formed crystalline structure is that of the parent homopolymers. The fast crystallization of PiPOx confines the observed superstructure. The BCPs were studied on multiple length scales -from the atomic level (WAXS, IR spectroscopy) to the meso level (AFM, SAXS) and the macroscopic superstructure ( polarized optical microscopy). A mechanism of the structure evolution is presented.

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Thermoresponsive poly(2-oxazoline)s, polypeptoids, and polypeptides

Abstract: This review covers the recent advances in the emerging field of thermoresponsive polyamides or polymeric amides, i.e., poly(2-oxazoline)s, polypeptoids, and polypeptides, with a specific focus on structure-thermoresponsive property relationships, self-assembly, and applications

Cited by 256 publications

References 136 publications

Session 5: Young Scientist Forum

Session 5: Young Scientist Forum

Poly(2-ethyl-2-oxazoline-co-N-propylethylene imine)s by controlled partial reduction of poly(2-ethyl-2-oxazoline)

Inversion of crystallization rates in miscible block copolymers of poly(lactide)-block-poly(2-isopropyl-2-oxazoline)

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