A facile one-step gelation approach simultaneously combining physical and chemical cross-linking for the preparation of injectable hydrogels

2017 ◽  
Vol 5 (17) ◽  
pp. 3145-3153 ◽  
Author(s):  
Haofang Zhu ◽  
Xiaojun Cai ◽  
Lihuang Wu ◽  
Zhongwei Gu
Keyword(s):  
Cross Linking ◽  
Injectable Hydrogels ◽  
One Step ◽  
Physical And Chemical ◽  
Chemical Cross Linking

Process Control of Loss Factor in Soft Materials

2006 ◽  
Vol 11-12 ◽  
pp. 725-728
Author(s):  
Jun Hao Wu ◽  
Yoshitaka Ikarashi ◽  
Shuji Fujii ◽  
Seiichi Kawahara ◽  
Yoshinobu Isono
Keyword(s):  
Loss Tangent ◽  
Loss Modulus ◽  
Soft Materials ◽  
Polymer Chains ◽  
Cross Linking ◽  
Unstable State ◽  
High Loss ◽  
One Step ◽  
Deformed State ◽  
Chemical Cross Linking

Loss tangent defined by the ratio of loss modulus to storage modulus, G”/G’, is widely used as a measure of energy loss for rubber materials. We can expect high loss tangent due to unstable state of polymer chains in large deformation. However, chemical cross-linking is usually introduced in no deformation where we cannot expect high loss tangent. Even if introduced in deformed state, polymer chains take relaxation before completion of cross-linking. In this study, hence, a novel two-step cure has been proposed. The loss tangent by two-step cure has been found to be higher than that by one-step cure in no deformation, showing effectiveness of the process proposed.

scholarly journals Differentiation of physical and chemical cross-linking in gelatin methacryloyl hydrogels

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lisa Rebers ◽  
Raffael Reichsöllner ◽  
Sophia Regett ◽  
Günter E. M. Tovar ◽  
Kirsten Borchers ◽  
...  
Keyword(s):  
Near Infrared ◽  
Cross Linking ◽  
Cross Link ◽  
Scanning Calorimetry ◽  
Link Density ◽  
Double Bond Conversion ◽  
Cross Links ◽  
Physical And Chemical ◽  
The Impact ◽  
Chemical Cross Linking

AbstractGelatin methacryloyl (GM) hydrogels have been investigated for almost 20 years, especially for biomedical applications. Recently, strengthening effects of a sequential cross-linking procedure, whereby GM hydrogel precursor solutions are cooled before chemical cross-linking, were reported. It was hypothesized that physical and enhanced chemical cross-linking of the GM hydrogels contribute to the observed strengthening effects. However, a detailed investigation is missing so far. In this contribution, we aimed to reveal the impact of physical and chemical cross-linking on strengthening of sequentially cross-linked GM and gelatin methacryloyl acetyl (GMA) hydrogels. We investigated physical and chemical cross-linking of three different GM(A) derivatives (GM10, GM2A8 and GM2), which provided systematically varied ratios of side-group modifications. GM10 contained the highest methacryloylation degree (DM), reducing its ability to cross-link physically. GM2 had the lowest DM and showed physical cross-linking. The total modification degree, determining the physical cross-linking ability, of GM2A8 was comparable to that of GM10, but the chemical cross-linking ability was comparable to GM2. At first, we measured the double bond conversion (DBC) kinetics during chemical GM(A) cross-linking quantitatively in real-time via near infrared spectroscopy-photorheology and showed that the DBC decreased due to sequential cross-linking. Furthermore, results of circular dichroism spectroscopy and differential scanning calorimetry indicated gelation and conformation changes, which increased storage moduli of all GM(A) hydrogels due to sequential cross-linking. The data suggested that the total cross-link density determines hydrogel stiffness, regardless of the physical or chemical nature of the cross-links.

Hybrid Nanogels with Physical and Chemical Cross-Linking Structures as Nanocarriers

2005 ◽  
Vol 5 (8) ◽  
pp. 710-716 ◽  
Author(s):  
Nobuyuki Morimoto ◽  
Takao Endo ◽  
Michiko Ohtomi ◽  
Yasuhiko Iwasaki ◽  
Kazunari Akiyoshi
Keyword(s):  
Cross Linking ◽  
Physical And Chemical ◽  
Chemical Cross Linking

scholarly journals Cross-Linking Strategies for Electrospun Gelatin Scaffolds

Materials ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2476 ◽  
Author(s):  
Chiara Emma Campiglio ◽  
Nicola Contessi Negrini ◽  
Silvia Farè ◽  
Lorenza Draghi
Keyword(s):  
Low Cost ◽  
Cross Linking ◽  
Fiber Morphology ◽  
Natural Polymers ◽  
Wide Availability ◽  
Fiber Scaffolds ◽  
Electrospun Gelatin ◽  
Physical And Chemical ◽  
Synthetic And Natural Polymers ◽  
Chemical Cross Linking

Electrospinning is an exceptional technology to fabricate sub-micrometric fiber scaffolds for regenerative medicine applications and to mimic the morphology and the chemistry of the natural extracellular matrix (ECM). Although most synthetic and natural polymers can be electrospun, gelatin frequently represents a material of choice due to the presence of cell-interactive motifs, its wide availability, low cost, easy processability, and biodegradability. However, cross-linking is required to stabilize the structure of the electrospun matrices and avoid gelatin dissolution at body temperature. Different physical and chemical cross-linking protocols have been described to improve electrospun gelatin stability and to preserve the morphological fibrous arrangement of the electrospun gelatin scaffolds. Here, we review the main current strategies. For each method, the cross-linking mechanism and its efficiency, the influence of electrospinning parameters, and the resulting fiber morphology are considered. The main drawbacks as well as the open challenges are also discussed.

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