scholarly journals Cross-Linking Optimization for Electrospun Gelatin: Challenge of Preserving Fiber Topography

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2472
Author(s):  
Chiara Emma Campiglio ◽  
Selene Ponzini ◽  
Paola De Stefano ◽  
Giulia Ortoleva ◽  
Lorenzo Vignati ◽  
...  
Keyword(s):  
Chemical Cues ◽  
Cross Linking ◽  
Fiber Morphology ◽  
Fiber Network ◽  
Specific Chemical ◽  
Naturally Occurring ◽  
Effective Combination ◽  
Significant Impairment ◽  
Fibrous Morphology ◽  
Electrospun Gelatin

Opportunely arranged micro/nano-scaled fibers represent an extremely attractive architecture for tissue engineering, as they offer an intrinsically porous structure, a high available surface, and an ideal microtopography for guiding cell migration. When fibers are made with naturally occurring polymers, matrices that closely mimic the architecture of the native extra-cellular matrix and offer specific chemical cues can be obtained. Along this track, electrospinning of collagen or gelatin is a typical and effective combination to easily prepare fibrous scaffolds with excellent properties in terms of biocompatibility and biomimicry, but an appropriate cross-linking strategy is required. Many common protocols involve the use of swelling solvents and can result in significant impairment of fibrous morphology and porosity. As a consequence, the efforts for processing gelatin into a fiber network can be vain, as a film-like morphology will be eventually presented to cells. However, this appears to be a frequently overlooked aspect. Here, the effect on fiber morphology of common cross-linking protocols was analyzed, and different strategies to improve the final morphology were evaluated (including alternative solvents, cross-linker concentration, mechanical constraint, and evaporation conditions). Finally, an optimized, fiber-preserving protocol based on carbodiimide (EDC) chemistry was defined.

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.

Electrospun gelatin nanofibers: Optimization of genipin cross-linking to preserve fiber morphology after exposure to water

2011 ◽  
Vol 7 (4) ◽  
pp. 1702-1709 ◽  
Author(s):  
Silvia Panzavolta ◽  
Michela Gioffrè ◽  
Maria Letizia Focarete ◽  
Chiara Gualandi ◽  
Laura Foroni ◽  
...  
Keyword(s):  
Cross Linking ◽  
Fiber Morphology ◽  
Electrospun Gelatin

Roles of actin cross-linking proteins in the force transmission in stress fiber network

2020 ◽  
Vol 2020.31 (0) ◽  
pp. 1A32
Author(s):  
Gaku MOTOORI ◽  
Tsubasa S. MATSUI ◽  
Daiki MATSUNAGA ◽  
Kentaroh NOI ◽  
Shinji DEGUCHI
Keyword(s):  
Stress Fiber ◽  
Cross Linking ◽  
Force Transmission ◽  
Fiber Network

Insect–Plant Interactions: A Multilayered Relationship

2020 ◽  
Author(s):  
Garima Sharma ◽  
Praful Ashokrao Malthankar ◽  
Vartika Mathur
Keyword(s):  
Plant Resistance ◽  
Crucial Role ◽  
Chemical Cues ◽  
Defense Responses ◽  
Trophic Levels ◽  
Plant Interactions ◽  
Plant Metabolites ◽  
Specific Chemical ◽  
Plant Interaction ◽  
Morphological Defense

Abstract During herbivory, insects recognize their host plant based on specific chemical cues, whereas the plants induce various chemical and morphological defense responses to resist this attack. However, the seemingly bidirectional insect–plant interaction involves various confounding aspects that influence the performance and fitness of the two participants. These interactions are often mediated by associated microbiota, competitors, predators, and parasitoids that interact in either obligate or facultative manner. Insect endosymbionts play a crucial role in the perception, nutrition, metabolism as well as reproduction of their host, which together determine its survival and fitness on the plant. Endosymbionts also help their host to overcome plant defenses by detoxifying plant metabolites. On the contrary, plant-associated microbes contribute in induced systemic plant resistance by enhancing chemical and morphological defense. These interactions determine the association of insect and plant, not only with the high trophic levels but also with the ecosystem as a whole. Thus, insect–plant interaction is a multilayered relationship extending to various micro- and macro-organisms associated either temporally or spatially. All these relationships may be considered to obtain a wholesome perspective of the natural environment.

scholarly journals Fire-Borne Life: A Brief Review of Smoke-Induced Germination

2019 ◽  
Vol 14 (9) ◽  
pp. 1934578X1987292 ◽  
Author(s):  
Vilmos Soós ◽  
Eszter Badics ◽  
Norbert Incze ◽  
Ervin Balázs
Keyword(s):  
Species Diversity ◽  
Organic Material ◽  
Scientific Community ◽  
Chemical Cues ◽  
Current Knowledge ◽  
Early Observation ◽  
Controlled Burning ◽  
Naturally Occurring ◽  
Plant Life ◽  
Physical Effects

Naturally occurring fires have been shaping landscapes long before mankind existed. Presumably, it is an early observation that in some habitats, fire is crucial to maintaining species diversity and for the rejuvenation of the vegetation, and so early settled farmers might have started to take advantage of the controlled burning of a desired area. The heat of fire is essential to break the dormancy of many fire ephemerals and for the seed release of some serotinous or woody taxa. Besides the physical effects caused by the heat on seeds, smoke and burnt organic material contain chemical cues that regulate the germination of seeds and the early development of seedlings. The scientific community really started to reveal the secrets of these enigmatic components from the early 1990s, although there are still a number of questions to be answered. In this review, we briefly introduce the path which leads to our current knowledge on smoke-derived compounds and their enormous effects on plant life.

scholarly journals Site-Directed Disulfide Cross-Linking Shows that Cleft Flexibility in the Periplasmic Domain Is Needed for the Multidrug Efflux Pump AcrB of Escherichia coli

2007 ◽  
Vol 189 (23) ◽  
pp. 8677-8684 ◽  
Author(s):  
Yumiko Takatsuka ◽  
Hiroshi Nikaido
Keyword(s):  
Escherichia Coli ◽  
Conformational Changes ◽  
Disulfide Bonds ◽  
Drug Transport ◽  
Site Directed Mutagenesis ◽  
Cross Linking ◽  
Cysteine Residues ◽  
Multidrug Efflux ◽  
Specific Chemical ◽  
Periplasmic Domain

ABSTRACT Escherichia coli AcrB is a multidrug efflux transporter that recognizes multiple toxic chemicals having diverse structures. Recent crystallographic studies of the asymmetric trimer of AcrB suggest that each protomer in the trimeric assembly goes through a cycle of conformational changes during drug export. However, biochemical evidence for these conformational changes has not been provided previously. In this study, we took advantage of the observation that the external large cleft in the periplasmic domain of AcrB appears to become closed in the crystal structure of one of the three protomers, and we carried out in vivo cross-linking between cysteine residues introduced by site-directed mutagenesis on both sides of the cleft, as well as at the interface between the periplasmic domains of the AcrB trimer. Double-cysteine mutants with mutations in the cleft or the interface were inactive. The possibility that this was due to the formation of disulfide bonds was suggested by the restoration of transport activity of the cleft mutants in a dsbA strain, which had diminished activity to form disulfide bonds in the periplasm. Furthermore, rapidly reacting, sulfhydryl-specific chemical cross-linkers, methanethiosulfonates, inactivated the AcrB transporter with double-cysteine residues in the cleft expressed in dsbA cells, and this inactivation could be observed within a few seconds after the addition of a cross-linker in real time by increased ethidium influx into the cells. These observations indicate that conformational changes, including the closure of the external cleft in the periplasmic domain, are required for drug transport by AcrB.

Engineering oxidative stability in human hemoglobin based on the Hb providence (βK82D) mutation and genetic cross-linking

2017 ◽  
Vol 474 (24) ◽  
pp. 4171-4192 ◽  
Author(s):  
Michael Brad Strader ◽  
Rachel Bangle ◽  
Claire J. Parker Siburt ◽  
Cornelius L. Varnado ◽  
Jayashree Soman ◽  
...  
Keyword(s):  
Oxidative Degradation ◽  
Oxygen Affinity ◽  
Side Chain ◽  
Cross Linking ◽  
Critical Element ◽  
Low Oxygen ◽  
Naturally Occurring ◽  
Low Concentrations ◽  
Genetic Cross ◽  
Low Oxygen Affinity

Previous work suggested that hemoglobin (Hb) tetramer formation slows autoxidation and hemin loss and that the naturally occurring mutant, Hb Providence (HbProv; βK82D), is much more resistant to degradation by H2O2. We have examined systematically the effects of genetic cross-linking of Hb tetramers with and without the HbProv mutation on autoxidation, hemin loss, and reactions with H2O2, using native HbA and various wild-type recombinant Hbs as controls. Genetically cross-linked Hb Presbyterian (βN108K) was also examined as an example of a low oxygen affinity tetramer. Our conclusions are: (a) at low concentrations, all the cross-linked tetramers show smaller rates of autoxidation and hemin loss than HbA, which can dissociate into much less stable dimers and (b) the HbProv βK82D mutation confers more resistance to degradation by H2O2, by markedly inhibiting oxidation of the β93 cysteine side chain, particularly in cross-linked tetramers and even in the presence of the destabilizing Hb Presbyterian mutation. These results show that cross-linking and the βK82D mutation do enhance the resistance of Hb to oxidative degradation, a critical element in the design of a safe and effective oxygen therapeutic.

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