The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Pasquale Sacco - One of the best experts on this subject based on the ideXlab platform.
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Ionotropic Gelation of chitosan flat structures and potential applications
Molecules, 2021Co-Authors: Pasquale Sacco, Seidy Pedrososantana, Yogesh Kumar, Nicolas Joly, Patrick Martin, Patrizia BocchettaAbstract:The capability of some polymers, such as chitosan, to form low cost gels under mild conditions is of great application interest. Ionotropic Gelation of chitosan has been used predominantly for the preparation of gel beads for biomedical application. Only in the last few years has the use of this method been extended to the fabrication of chitosan-based flat structures. Herein, after an initial analysis of the major applications of chitosan flat membranes and films and their usual methods of synthesis, the process of Ionotropic Gelation of chitosan and some recently proposed novel procedures for the synthesis of flat structures are presented.
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insight into the Ionotropic Gelation of chitosan using tripolyphosphate and pyrophosphate as cross linkers
International Journal of Biological Macromolecules, 2016Co-Authors: Pasquale Sacco, Sergio Paoletti, Michela Cok, Fioretta Asaro, Michela Abrami, Mario Grassi, Ivan DonatiAbstract:Ionotropic Gelation of chitosan by means of opposite charged ions represents an efficient alternative to covalent reticulation because of milder condition of use and, in general, higher biocompatibility of the resulting systems. In this work 90° light scattering (turbidimetry), circular dichroism (CD) and 1H NMR measurements have been performed to study the interactions between the biopolymer and ionic cross-linkers tripolyphosphate (TPP) and pyrophosphate (PPi) in dilute solutions. Thereafter, a dialysis-based technique was exploited to fabricate tridimensional chitosan hydrogels based on both polyanions. Resulting matrices showed a different mechanical behavior because of their peculiar mesh-texture at micro/nano-scale: in the present contribution we demonstrate that TPP and PPi favor the formation of homogeneous and inhomogeneous systems, respectively. The different texture of networks could be exploited in future for the preparation of systems for the controlled release of molecules.
Michael Gelinsky - One of the best experts on this subject based on the ideXlab platform.
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novel biomaterials with parallel aligned pore channels by directed Ionotropic Gelation of alginate mimicking the anisotropic structure of bone tissue
2011Co-Authors: Florian Despang, Rosemarie Dittrich, Michael GelinskyAbstract:Regenerative medicine intends to restore lost functionality by healing tissues defects. For this novel types of biodegradable implants have to be used that first foster healing and later take part in the natural remodelling cycle of the body. In this way, patient’s cells can reconstruct and adapt the tissue according to the local situation and needs. Ideally, the implant should mimic the desired tissue. That means that the biomaterial should resemble the extracellular matrix (ECM) which is expressed by specific cells and acts as the biological scaffold of living tissues. The closer an artificial scaffold material mimics the pattern the easier it can be involved in the natural healing and remodelling processes, which is why more and more researchers try to establish biomimetic approaches for the development of tissue engineering scaffolds. Biological materials are seldom isotropic and for many tissue engineering applications distinct anisotropic materials are needed. E. g. compact bone exhibits a honeycomb-like structure with overlapping, cylindrical units (osteons) with the so-called Haversian canal in the centre. Scaffolds with parallel aligned pores, mimicking the osteon structure of compact bone can be synthesised by directed Ionotropic Gelation of the naturally occurring polysaccharide alginate. The parallel channels are formed via a sol-gel-process when dior multivalent cations diffuse into the sol in broad front, forming an alginate hydrogel. The pore size and pore alignment of such gels is influenced by the starting materials (e.g. concentrations, additives like powders or polymers) and the preparation process (e.g. temperature, drying process). The phenomenon was discovered already in the 50th of the last century but the biomedical potential of alginate scaffolds with parallel aligned pores structured by Ionotropic Gelation has been explored for osteoblasts, stem cell based tissue engineering, axon guiding or co-culture of vascular and muscle cells only in the past few years.
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scaffolds for hard tissue engineering by Ionotropic Gelation of alginate influence of selected preparation parameters
Journal of the American Ceramic Society, 2007Co-Authors: Rosemarie Dittrich, G Tomandl, Florian Despang, Anne Bernhardt, T Hanke, Wolfgang Pompe, Michael GelinskyAbstract:Cylindrical constructs with parallel aligned pores were prepared by using Ionotropic Gelation of alginate/calcium phosphate hydroxyapatite (HAP) mixtures in regard to applications as scaffold for bone regeneration. The starting powder and stabilizing agents were characterized by measurement of electrosonic amplitude, particle size distribution, and specific surface. The shrinkage of the gels was investigated in dependence on the drying methods. The pore size relied on preparation conditions such as amount of HAP and concentrations of gelling agent or alginate sol. A wide field of pore sizes could be fabricated by varying the kind and concentration of additives. Micro computer tomography-investigations of freeze dried scaffolds demonstrated the pore progression over a length of 4 mm. The pore dimension and structure were adequate for cell seeding and blood capillary ingrowth. Biocompatibility was proven by in vitro experiments with human mesenchymal stem cells by fluorescence microscopy. A high stability of the wet gels was maintained under cell culture conditions for a period of 3 weeks.
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mineralized scaffolds for hard tissue engineering by Ionotropic Gelation of alginate
Advances in Science and Technology, 2006Co-Authors: Rosemarie Dittrich, G Tomandl, Florian Despang, Anne Bernhardt, T Hanke, Wolfgang Pompe, A Mannschatz, Michael GelinskyAbstract:Alginates form gels with tube-like pores when covered with solutions of di- or trivalent cations. This phenomenon also referred to as Ionotropic Gelation has been known for more than 30 years. By mixing a calcium phosphate powder and an alginate as the starting material, the mineral phase of bone is incorporated. Such porous structures can be used for scaffolds in hard tissue engineering. The starting materials and stabilizing additives are dispersed in an aqueous solution. Then a solution of Ca-ions is deposited onto the surface of the slurry. The slurry can be gelled by ion exchange of Na-ions in the alginate with Ca-ions. A primary thin gel layer with the function of a membrane is immediately formed. By diffusional control of cation transport through the membrane, the slurry gradually transforms to the gel forming tube-like pores in direction of cation diffusion. Like the Gelation of pure alginate the concentration of electrolyte and the kind of cations and anions influence the size (diameter and length) and size growth of the pores, but the tolerance in the preparation conditions is much smaller. The diameters of the pores can be adjusted between 50 and 500 m which fits the optimum size for cell seeding and blood capillary ingrowth very well. By selecting the proper drying method the inherent shrinkage can be controlled. Hydroxyapatite sintered at high temperatures loses the ability to be resorbed by osteoclasts in vivo. Therefore, we have developed scaffolds with channel-like pores from alginate/calcium phosphate composites without the necessity for heating them to higher temperatures.
Sang Jae Kim - One of the best experts on this subject based on the ideXlab platform.
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Worm structure piezoelectric energy harvester using Ionotropic Gelation of barium titanate-calcium alginate composite
Energy, 2017Co-Authors: Nagamalleswara Rao Alluri, Gae Myoung Lee, B. Saravanakumar, Arunkumar Chandrasekhar, Ji Hyun Jeong, Sandhiya Selvarajan, Sang Jae KimAbstract:A laterally aligned flexible composite linear worm-based piezoelectric energy harvester made up of piezoelectric barium titanate nanoparticles and a three dimensional gel network of calcium alginate biopolymer was aimed to harness the low frequency mechanical energy. It is highly desirable to fabricate innovative micro/nanostructures for high performance energy harvesting beyond the conventional thin films, and small scale fabrication of nanowires (or rods). The open circuit voltage of a single composite worm-based energy harvester (diameter�≈�550�μm, length�≈�2.5�cm) increases up to 5 times by increasing the frequency of mechanical load (11�N) from 3 to 20�Hz. Similarly, 1.5 times voltage increment was observed by increasing the length of the composite worm from 1.5 to 3.5�cm upon the bio-mechanical hand force. The energy harvester can function as an efficient portable/wearable self-powered device due to its good flexibility, and multiple lengths of composite linear worms can be utilized to drive low-power electronic devices. In this work, the composite worms were prepared by an Ionotropic Gelation approach, which is eco-friendly, non-toxic, having low processing temperature/time, and potential for cost-effective, large-scale fabrication, making it suitable for low frequency based self-powered devices.
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self powered ph sensor using piezoelectric composite worm structures derived by Ionotropic Gelation approach
Sensors and Actuators B-chemical, 2016Co-Authors: Nagamalleswara Rao Alluri, Arunkumar Chandrasekhar, Ji Hyun Jeong, Sophia Selvarajan, Saravanakumar Balasubramaniam, Sang Jae KimAbstract:Abstract Multifunctional biopolymer-piezoelectric composite worm structures (wavy and linear) derived by Ionotropic Gelation technique is fundamentally reported. Mass production of composite wavy pattern worms (CWPWs) enable high energy conversion from low frequency mechanical energy to electrical energy, tunable piezoelectricity by tailored length dependent CWPWs, weight ratio of piezoelectric nanoparticles. Interestingly we found that, the peak–peak voltage and current decreases around 87% and 71% for CWPW devices when the CWPWs length decreased to 56.4% (L = 1.95 to 0.85 cm) respectively. We also tested, the pH dependent conductivity of composite linear worm (CLW) for clinical, food monitoring applications. Next, we demonstrate the generated piezoelectric potential of CWPW device holds as a promising independent power source unit to drive the CLW sensor under different pH solutions. The proposed work is non-invasive, flexible with robustness in long-term effective usage, biocompatibility, and battery-less operation for self powered biosensor in theranostics, blood pH measurement.
Ivan Donati - One of the best experts on this subject based on the ideXlab platform.
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insight into the Ionotropic Gelation of chitosan using tripolyphosphate and pyrophosphate as cross linkers
International Journal of Biological Macromolecules, 2016Co-Authors: Pasquale Sacco, Sergio Paoletti, Michela Cok, Fioretta Asaro, Michela Abrami, Mario Grassi, Ivan DonatiAbstract:Ionotropic Gelation of chitosan by means of opposite charged ions represents an efficient alternative to covalent reticulation because of milder condition of use and, in general, higher biocompatibility of the resulting systems. In this work 90° light scattering (turbidimetry), circular dichroism (CD) and 1H NMR measurements have been performed to study the interactions between the biopolymer and ionic cross-linkers tripolyphosphate (TPP) and pyrophosphate (PPi) in dilute solutions. Thereafter, a dialysis-based technique was exploited to fabricate tridimensional chitosan hydrogels based on both polyanions. Resulting matrices showed a different mechanical behavior because of their peculiar mesh-texture at micro/nano-scale: in the present contribution we demonstrate that TPP and PPi favor the formation of homogeneous and inhomogeneous systems, respectively. The different texture of networks could be exploited in future for the preparation of systems for the controlled release of molecules.
Nora J Francois - One of the best experts on this subject based on the ideXlab platform.
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chitosan starch beads prepared by Ionotropic Gelation as potential matrices for controlled release of fertilizers
Carbohydrate Polymers, 2016Co-Authors: Jonas Jose Perez, Nora J FrancoisAbstract:The present study examines the agrochemical application of macrospheres prepared with chitosan and chitosan-starch blends by an easy dripping technique, using a sodium tripolyphosphate aqueous solution as the crosslinking agent. These biopolymers form hydrogels that could be a viable alternative method to obtain controlled-release fertilizers (CRFs). Three different concentrations (ranging from 20 to 100wt/wt% of chitosan) and two crosslinking times (2 or 4h) were used. The resulting polymeric matrices were examined by scanning electron microscopy coupled with energy dispersive X-ray, X-ray diffraction, Fourier transform infrared spectroscopy, solid-state nuclear magnetic resonance, thermogravimetric analysis and differential scanning calorimetry. Ionotropic Gelation and neutralization induced the formation of the macrospheres. The crosslinking time and the composition of the polymeric hydrogel controlled the crosslinking degree, the swelling behavior and the fertilizer loading capability. Potassium nitrate-loaded beads were shown to be useful as a controlled-release fertilizer. After 14days of continuous release into distilled water, the cumulative concentration in the release medium reached between 70 and 93% of the initially loaded salt, depending on the matrix used. The prepared beads showed properties that make them suitable for use in the agrochemical industry as CRFs.
