دانلود رایگان مقاله لاتین کنفورماسیونی از سایت الزویر
عنوان فارسی مقاله:
حرارت و PH ناشی از تغییرات کنفورماسیونی BSA، تشکیل و کاربرد هیدروژل به عنوان داربست سلول
عنوان انگلیسی مقاله:
Heat- and pH-induced BSA conformational changes, hydrogel formation and application as 3D cell scaffold
سال انتشار : 2016
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مقدمه انگلیسی مقاله:
1. Introduction
Many globular proteins have the ability to form gels, both by heat and cold treatments. It is well known that under appropriate conditions, native proteins can undergo conformational changes associated with partial unfolding or denaturation that may lead to aggregation [1,2] up to gelation, above a critical protein concentration [3]. Protein aggregation is a complex process made by different and simultaneous steps: first the protein partially unfolds and goes towards molten globule forms or intermediate states also called amorphous pre-aggregates [4,5]; second, these different aggregates in appropriate experimental conditions can form amorphous aggregates, fibrils and fibers [6]. Under appropriate conditions, depending on several factors among which the protein concentration, the temperature and the pH, these aggregates can be the bricks of protein hydrogels [7,8]. Recently, the fabrication of gels from biological molecules, in particular from proteins, has received increasing interest due to their applications in the field of biomedical research [9e12]. The protein-based hydrogels can be biocompatible and biodegradable [12], can entrap large amounts of water or biological fluids [13], have a microporous structure and provide an excellent mechanical support through their three-dimensional structure [14,15]. These properties make them ideal biomaterials also to be used as devices for encapsulation and protection of sensitive materials and pHsensitive hydrogels for the controlled delivery of biologicallyactive drugs [16e18]. As an example, the microscopic and macroscopic properties of these hydrogels can be controlled by changing the pH value: particulate, brittle and opaque gel can be formed close to the protein isoelectric point, while more flexible and transparent gel, made of linear aggregates, far from the isoelectric point [19].Recent studies have demonstrated that gels formed by fibrillar aggregates are more prone to promoting cell attachment and neurite outgrowth, while hydrogels, having different structure, do not show any biological activity [15,20]. Thus, the well-known general tendency of the globular proteins to fibrillation and gelation can be taken as an advantage to generate new forms of nanoscale biomaterials based on the amyloid fibrillar architecture, since they are characterized by well-ordered and stable structures that can be formed by self-association in aqueous solution [21,22]. The surplus value, consisting in their highly ordered network stabilized by intermolecular and/or intramolecular hydrogen bonding, electrostatic interactions, and hydrophobic effects, makes the fibrillar hydrogels a versatile device usable as scaffold in tissue engineering [20]. Gels made by biocompatible physically cross-linked protein molecules, should be used for scaffolds, controlled drug delivery, or uptake of biological molecules [23]. Indeed, biodegradable hydrogels capable of phase transition in response to external stimuli such as temperature or pH values represent an alternative method of preparing injectable hydrogels for biomedical applications [23]. It is important to emphasize that the relevant properties of biocompatibility are not affected by using a gel formed by mature fibrils. Fibrils are the final state of aggregated and re-organized protofibrils and it is now established that prefibrillar oligomers [24e27] rather than mature fibrils are the prime toxic agents [27e29] responsible of the amyloid-induced cellular toxicity. In this paper, we report results obtained by exploiting the natural tendency of bovine serum albumin (BSA) to self-organize in 3D network, for the production of new protein-based materials. The main aim of our work has been to determine the appropriate experimental conditions to obtain hydrogels of BSA aggregates and to characterized the hydrogels thus formed. Albumin is an abundant and low-cost protein with a molecular weight of 66 kDa, in some forms also human-compatible and with well-known properties [1,30,31]. It is an important natural carrier of hydrophobic molecules and a polyampholyte with pH-dependent charge. After heating or cooling treatments it can form hydrogels [32], ideal candidates for loading and releasing drugs, since its sites can be reversibly used to bind and release drugs by regulating pH value [18,33]. In this work we have characterized the conformation and the morphology of the BSA heat-induced aggregates, namely the fundamental “bricks” of the network, and investigated if the modifications of the pH and protein concentration can induce hydrogels with different structural properties when subjected to prolonged heating. The conformational and structural changes of the protein during incubation at 60 C were studied by FTIR spectroscopy. The aggregation growth and the gelation process were followed by FTIR and rheological measurements up to 20 h from the beginning of the experiments. Information about the morphology of the aggregates during the gelation process were obtained by atomic force microscopy (AFM). Finally, micrographs of the different kinds of hydrogels were made by SEM measurements and biological tests on LAN5 cell cultures have been also performed. Our results indicate that it is possible to modulate the final texture of the hydrogels by tuning pH and protein concentration for the appropriate applications.
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کلمات کلیدی:
PH-Induced conformational changes of BSA in ... - ResearchGate https://www.researchgate.net/.../257346121_PH-Induced_conformational_changes_of_... We investigated the pH-induced fluorescence changes of BSA-protected gold nanoclusters, Au16NCs@BSA, and the corresponding conformational changes of ... Investigation of pH-Induced Protein Conformation Changes by ... pubs.acs.org/doi/abs/10.1021/la403981t by G Thakur - 2014 - Cited by 9 - Related articles Feb 10, 2014 - Investigation of pH-Induced Protein Conformation Changes by ... Quenching interaction of BSA with DTAB is dynamic in nature: A ... Isothermal titration calorimetric studies of the pH induced ... link.springer.com/content/pdf/10.1007/s10973-009-0040-5.pdf by R Kun - 2009 - Cited by 28 - Related articles Jun 19, 2009 - Isothermal titration calorimetric studies of the pH induced conformational changes of bovine serum albumin. Robert Kun Æ Márta Szekeres Æ ... Conformational Transitions of the Three Recombinant Domains of ... www.jbc.org/content/275/5/3042.long by M Dockal - 2000 - Cited by 401 - Related articles Feb 4, 2000 - The acid-induced structural changes of bovine and human serum albumin ... pH 7.0 and 9.0, HSA and BSA undergo another conformational ... The Importance of Protein-Protein Interactions on the pH-Induced ... www.cell.com/biophysj/abstract/S0006-3495(09)01570-7 by LRS Barbosa - 2010 - Cited by 98 - Related articles Jan 6, 2010 - The Importance of Protein-Protein Interactions on the pH-Induced Conformational Changes of Bovine Serum Albumin: A Small-Angle X-Ray ... Advances in Serum Albumin Research and Application: 2012 Edition https://books.google.com/books?isbn=1464997578 2012 - Medical (2011 AUG 3) University of Sao Paulo: The importance of protein-protein interactions on the pH-induced conformational changes of bovine serum albumin - a ... Advances in Serum Albumin Research and Application: 2011 Edition https://books.google.com/books?isbn=1464930198 2012 - Medical (2010 MAR 22) University of Sao Paulo: The importance of protein-protein interactions on the pH-induced conformational changes of bovine serum albumin: a ...
