Viscoelastic Oxidized Alginates with Reversible Imine Type Crosslinks: Self-Healing, Injectable, and Bioprintable Hydrogels

Hafeez, Shahzad; Ooi, Huey Wen; Morgan, Francis L. C.; Mota, Carlos; Dettin, Monica; Blitterswijk, Clemens van; Moroni, Lorenzo; Baker, Matthew B.

doi:10.3390/gels4040085

Cited by 78 publications

(110 citation statements)

References 55 publications

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“…Alginate (Alg) hydrogels have long been proposed for drug delivery 39,40 and tissue engineering applications 41,42 , as well as bioinks. 43,44 Alg and mucin have been previously mixed to disclose the mechanism of interaction relevant in CF. 45,46 On the basis of this knowledge, we propose the combination of mucin and Alg in a hydrogel to produce models of CF mucus.…”

Section: Alginate Hydrogelsmentioning

confidence: 99%

Disassembling the complexity of mucus barriers to develop a fast screening tool for early drug discovery

et al. 2019

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Section: Alginate Hydrogelsmentioning

confidence: 99%

Disassembling the complexity of mucus barriers to develop a fast screening tool for early drug discovery

et al. 2019

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“…Interestingly, the amino-functionalized Ca-alg MS were found to be reusable, still possessing more than 80% of their initial adsorption capacity after five consecutive treatment cycles. functionalities, which showed promising properties for bioprinting applications [106]. Alternatively, unmodified alg was cross-linked by bis-acetalization with glutaraldehyde, under acidic conditions.…”

Section: Other Functionalization Methodsmentioning

confidence: 99%

“…Finally, cross-linked hydrogels with high gelatin content promoted the formation of filopodial protusions during the osteogenic differentiation of microencapsulated human adipose-derived stem cells [105]. Other imine-based cross-linking strategies include the formation of oxime and semi-carbazone functionalities, which showed promising properties for bioprinting applications [106]. Alternatively, unmodified alg was cross-linked by bis-acetalization with glutaraldehyde, under acidic conditions.…”

Section: Cross-linked Hydrogels From Oxidized Alginatesmentioning

confidence: 99%

Strategies to Functionalize the Anionic Biopolymer Na-Alginate without Restricting Its Polyelectrolyte Properties

2020

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The natural anionic polyelectrolyte alginate and its derivatives are of particular interest for pharmaceutical and biomedical applications. Most interesting for such applications are alginate hydrogels, which can be processed into various shapes, self-standing or at surfaces. Increasing efforts are underway to functionalize the alginate macromolecules prior to hydrogel formation in order to overcome the shortcomings of purely ionically cross-linked alginate hydrogels that are hindering the progress of several sophisticated biomedical applications. Particularly promising are derivatives of alginate, which allow simultaneous ionic and covalent cross-linking to improve the physical properties and add biological activity to the hydrogel. This review will report recent progress in alginate modification and functionalization with special focus on synthesis procedures, which completely conserve the ionic functionality of the carboxyl groups along the backbone. Recent advances in analytical techniques and instrumentation supported the goal-directed modification and functionalization.Polymers 2020, 12, 919 2 of 23 Physicochemical and Polyelectrolyte Characteristics of AlginateThe composition, internal structure, and molar mass of the alg backbone govern the functional properties [9]. The solubility of alg in water depends on the pH value and the type of the counterions of the carboxyl groups. At pH < 3, both the M-and G-structures will precipitate as alginic acid. However, alternating M-and G-structures precipitate at lower pH values compared to the alg containing Polymers 2020, 12, 919 3 of 23 more homogeneous block structures. Neutralization of the alginic acid occurs at pH > 4, where it is converted into its corresponding salt [10]. Na-alg is an example of a water-soluble alg.Na-alg behaves in aqueous solution as a typical linear homogeneously charged polyelectrolyte. The chain conformation and consequently the solution viscosity strongly depend on the ionic strength, i.e., on both the alg concentration and the simultaneous presence of low molar mass salt. The intramolecular electrostatic repulsion between the neighboring negatively charged carboxyl groups of each monomer unit forces alg molecules into an extended random coil conformation in aqueous solution [11]. This results in highly viscous solutions even at relatively low alg concentration. The dynamic viscosity increases exponentially with the molar mass, while the intrinsic flexibility of the alg chains in solution increases in the order GG < MM < MG [12]. On the other hand, the selectivity for cation-binding and gel-forming properties strongly depends on the composition and sequence. Divalent cations preferably bind to the G-blocks. The ability to form ionotropic gels is based on this selective binding of cations. Mixing solutions of Na-alg with solutions of cationic polyelectrolytes yields precipitates of polyelectrolyte complexes.The rheological behavior of Na-alg solutions is important for a number of technologies and depends on both the concentration and th...

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“…This property can be used to design environments which enable cells to reorganize during the maturation process, a useful tool, for example, for researching developments of neuronal network formation. More recently, imine‐type dynamic covalent chemistry was also applied for bioink development . Partially oxidized alginate and linear, low molecular weight imine type crosslinkers (alkoxy, semicarbazide, and hydrazide) were used to adjust the viscoelastic properties of the bioinks through dynamic covalent crosslinks (oxime, semicarbazone, and hydrazone).…”

Section: Recent Progress For Controlling Shapementioning

confidence: 99%

“…Partially oxidized alginate and linear, low molecular weight imine type crosslinkers (alkoxy, semicarbazide, and hydrazide) were used to adjust the viscoelastic properties of the bioinks through dynamic covalent crosslinks (oxime, semicarbazone, and hydrazone). Secondary crosslinking was not necessary to ensure stability over seven days in vitro . Double network formation from dynamic covalent interactions and thiol–ene click photochemistry is another promising approach demonstrating the potential of dynamic covalent interactions for bioink development …”

Section: Recent Progress For Controlling Shapementioning

confidence: 99%

From Shape to Function: The Next Step in Bioprinting

et al. 2020

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In 2013, the “biofabrication window” was introduced to reflect the processing challenge for the fields of biofabrication and bioprinting. At that time, the lack of printable materials that could serve as cell‐laden bioinks, as well as the limitations of printing and assembly methods, presented a major constraint. However, recent developments have now resulted in the availability of a plethora of bioinks, new printing approaches, and the technological advancement of established techniques. Nevertheless, it remains largely unknown which materials and technical parameters are essential for the fabrication of intrinsically hierarchical cell–material constructs that truly mimic biologically functional tissue. In order to achieve this, it is urged that the field now shift its focus from materials and technologies toward the biological development of the resulting constructs. Therefore, herein, the recent material and technological advances since the introduction of the biofabrication window are briefly summarized, i.e., approaches how to generate shape, to then focus the discussion on how to acquire the biological function within this context. In particular, a vision of how biological function can evolve from the possibility to determine shape is outlined.

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Viscoelastic Oxidized Alginates with Reversible Imine Type Crosslinks: Self-Healing, Injectable, and Bioprintable Hydrogels

Cited by 78 publications

References 55 publications

Disassembling the complexity of mucus barriers to develop a fast screening tool for early drug discovery

Disassembling the complexity of mucus barriers to develop a fast screening tool for early drug discovery

Strategies to Functionalize the Anionic Biopolymer Na-Alginate without Restricting Its Polyelectrolyte Properties

From Shape to Function: The Next Step in Bioprinting

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