https://cyberleninka.org/article/n/933162.pdf

Hydrogels in drug delivery: progress and challenges

An overview of the recent developments in polylactide (PLA) research.

Novel crosslinking methods to design hydrogels

https://depositonce.tu-berlin.de/bitstream/11303/5674/1/c2np20085f.pdf

Ribosomally synthesized and post-translationally modified peptide natural products: Overview and recommendations for a universal nomenclature

With advances in tissue engineering, the possibility of regenerating injured tissue or failing organs has become a realistic prospect for the first time in medical history. Tissue engineering - the combination of bioactive materials with cells to generate engineered constructs that functionally replace lost and/or damaged tissue - is a major strategy to achieve this goal. One facet of tissue engineering is biofabrication, where three-dimensional tissue-like structures composed of biomaterials and cells in a single manufacturing procedure are generated. Cell-laden hydrogels are commonly used in biofabrication and are termed "bioinks". Hydrogels are particularly attractive for biofabrication as they recapitulate several features of the natural extracellular matrix and allow cell encapsulation in a highly hydrated mechanically supportive three-dimensional environment. Additionally, they allow for efficient and homogeneous cell seeding, can provide biologically-relevant chemical and physical signals, and can be formed in various shapes and biomechanical characteristics. However, despite the progress made in modifying hydrogels for enhanced bioactivation, cell survival and tissue formation, little attention has so far been paid to optimize hydrogels for the physico-chemical demands of the biofabrication process. The resulting lack of hydrogel bioinks have been identified as one major hurdle for a more rapid progress of the field. In this review we summarize and focus on the deposition process, the parameters and demands of hydrogels in biofabrication, with special attention to robotic dispensing as an approach that generates constructs of clinically relevant dimensions. We aim to highlight this current lack of effectual hydrogels within biofabrication and initiate new ideas and developments in the design and tailoring of hydrogels. The successful development of a "printable" hydrogel that supports cell adhesion, migration, and differentiation will significantly advance this exciting and promising approach for tissue engineering.

/pdf/25th-anniversary-article-engineering-hydrogels-for-52t0ojjbic.pdf

25th Anniversary Article: Engineering Hydrogels for Biofabrication

New insights into the hydrolytic degradation of poly(lactic acid): participation of the alcohol terminus

Glycidyl methacrylate derivatized dextran (dex-GMA) was synthesized by coupling of GMA to dextran in the presence of 4-(N,N-dimethylamino)pyridine using DMSO as an aprotic solvent and characterized by GPC, FTIR, and NMR. The structure of the product was established with 1 H and CH-COSY NMR. The degree of substitution, as determined by NMR, can be controlled by varying the molar ratio of GMA and dextran. Almost quantitative incorporation of GMA (>90%) was established. Hydrogels were prepared by radical polymerization of aqueous solutions of dex-GMA, using ammonium peroxydisulfate (APS) and N,N,N',N'-tetramethylethylenediamine (TEMED) as the initiating system. The polymerization rate, as determined by FTIR analysis, was dependent on the APS, the TEMED, and the dex-GMA concentration. By proper selection of the polymerization conditions, hydrogels could be obtained in which more than 95% of the methacrylate groups had reacted within 20 min.

Synthesis, characterization, and polymerization of glycidyl methacrylate derivatized dextran

Physically crosslinked dextran hydrogels by stereocomplex formation of lactic acid oligomers: degradation and protein release behavior.

This paper describes a novel hydrogel concept, which is based on self-assembling of enantiomeric lactic acid oligomers (stereocomplex formation) grafted to dextran. The hydrogels are prepared in an all-aqueous environment. For this purpose, l- and d-lactic acid oligomers were coupled to dextran, yielding dex−(l)lactate and dex−(d)lactate, respectively. Upon dissolving each product in water separately and mixing the solutions, we observed that a hydrogel is formed at room temperature as demonstrated by rheological measurements. The storage modulus of the obtained hydrogel strongly decreased upon heating to 80 °C, while it was restored upon cooling to 20 °C, demonstrating the thermoreversibility and the physical nature of the cross-links. Rheological experiments with monodisperse lactic acid oligomers grafted to dextran showed that the degree of polymerization (DP) of the lactic acid oligomers must be at least 11 to obtain a hydrogel. The hydrogel characteristics can be modulated by varying the degree of po...

Novel Self-assembled Hydrogels by Stereocomplex Formation in Aqueous Solution of Enantiomeric Lactic Acid Oligomers Grafted To Dextran

It is found that the reaction of glycidyl methacrylate with dextran proceeds via transesterification and results in the direct attachment of methacryloyl groups at the 2- and 3-hydroxyl group of the glucopyranose ring, in a 1:1 ratio

J. J. Kettenes-van den Bosch

Papers

New insights into the hydrolytic degradation of poly(lactic acid): participation of the alcohol terminus

Synthesis, characterization, and polymerization of glycidyl methacrylate derivatized dextran

Physically crosslinked dextran hydrogels by stereocomplex formation of lactic acid oligomers: degradation and protein release behavior.

Novel Self-assembled Hydrogels by Stereocomplex Formation in Aqueous Solution of Enantiomeric Lactic Acid Oligomers Grafted To Dextran

Reaction of Dextran with Glycidyl Methacrylate: An Unexpected Transesterification