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					Biomimetic poly(amidoamine) hydrogels as synthetic materials for cell culture

August 25

2009

Abstract Background: Poly(amidoamine)s (PAAs) are synthetic polymers endowed with many biologically interesting properties, being highly biocompatible, non toxic and biodegradable. Hydrogels based on PAAs can be easily modified during the synthesis by the introduction of functional comonomers. Aim of this work is the development and testing of novel amphoteric nanosized poly(amidoamine) hydrogel film incorporating 4-aminobutylguanidine (agmatine) moieties to create RGD-mimicking repeating units for promoting cell adhesion. Results: A systematic comparative study of the response of an epithelial cell line was performed on hydrogels with agmatine and on non-functionalized amphoteric poly(amidoamine) hydrogels and tissue culture plastic substrates. The cell adhesion on the agmatine containing substrates was comparable to that on plastic substrates and significantly enhanced with respect to the nonfunctionalized controls. Interestingly, spreading and proliferation on the functionalized supports are slower than on plastic exhibiting the possibility of an easier control of the cell growth kinetics. In order to favor the handling of the samples, a procedure for the production of bi-layered constructs was also developed by means the deposition via spin coating of a thin layer of hydrogel on a pretreated cover slip. Conclusion: The obtained results reveal that PAAs hydrogels can be profitably functionalized and, in general, undergo physical and chemical modifications to meet specific requirements. In particular the incorporation of agmatine warrants good potential in the field of cell culturing and the development of supported functionalized hydrogels on cover glass are very promising substrates for applications in cell screening devices.

A synthesis on the journal article of Biomimetic poly(amidoamine) hydrogels as synthetic materials for cell culture Submitted by: Kevin S. Cuarta Submitted to: Mr. Alvin B. Cervania

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iotechnology is technology based on biology, agriculture, food science, and medicine. Modern use of the term usually refers to genetic engineering as well as cell- and tissue culture technologies. However, the concept encompasses a wider range and history of procedures for modifying living things according to human purposes, going back to domestication of animals, cultivation of plants and "improvements" to these through breeding programs that employ artificial selection and hybridization. By comparison to biotechnology, bioengineering is generally thought of as a related field with its emphasis more on mechanical and higher systems approaches to interfacing with and exploiting living things. Evidence is the journal on the Biomimetic poly (amidoamines) hydrogels-are synthetic polymers higly biocompatible, non toxic and biodegradable. The research is profitable, in a way that it can build a functional amphoteric repeating unit which is structurally similar to RGD and the obtained results reveal that PAAs hydrogels can be profitably functionalized and, in general, undergo physical and chemical modifications to meet specific requirements. In particular the incorporation of agmatine warrants good potential in the field of cell culturing and the development of supported functionalized hydrogels on cover glass are very promising substrates for applications in cell screening devices. A short history of the name biomimetics was coined by Otto Schmitt in the 1950s. The term bionics was coined by Jack E. Steele in 1958 while working at the Aeronautics Division House at Wright-Patterson Air Force Base in Dayton. However, terms like biomimicry or biomimetics are more preferred in the technology world in efforts to avoid confusion between the medical term bionics. Coincidentally, Martin Caidin used the word for his 1972 novel Cyborg, which inspired the series The Six Million Dollar Man. Caidin was a long-time aviation industry writer before turning to fiction full time. The researchers accepted the hypothesis that PAA can be used in cell culture because they found out that it can be used to replace other tissues in the body only if performed properly. The journal research fall under the category of BIOREMEDIATION and BIODEGRADATION because bioremediation can be defined as any process that uses microorganisms, fungi, green plants or their enzymes to return the natural environment altered by contaminants to its original condition. Bioremediation may be employed to attack specific soil contaminants, such as degradation of chlorinated hydrocarbons by bacteria. An example of a more general approach is the cleanup of oil spills by the addition of nitrate and/or sulfate fertilizers to facilitate the decomposition of crude oil by indigenous or exogenous bacteria and biodegradation is the chemical breakdown of materials by a physiological environment. The term is often used in relation to ecology, waste management and environmental remediation (bioremediation). Organic material can be degraded aerobically with oxygen, or anaerobically, without oxygen. A term related to biodegradation is biomineralisation, in which organic matter is converted into minerals. Biosurfactant, an extracellular surfactant secreted by microorganisms, enhances the biodegradation process. And the only controversy I can see in this journal article is that cell adhesion on fully synthetic hydrogels, however, is still an issue for many of these materials, such as PHEMA or crosslinked PEG derivatives [9]. A number of chemical and physical modifications have been proposed to overcome this problem, often relying on modification of the synthetic surface with biological or biomimetic moieties,

like peptides or proteins. The process of cell adhesion to a substrate, both on the natural extracellular matrix (ECM) and synthetic materials is mediated by interactions between surface ligands and cell receptors, such as transmembrane integrins and proteoglycans. The tripeptide argininglycin aspartic acid (RGD), present in several ECM proteins, has been object of intensive research in the last years. In fact, several studies have shown that this tripeptide and some of its analogues can interact with adhesion regulating proteins of the integrin family, and play a role in promoting cell adhesion and spreading, mimicking the effect of some ECM proteins such as fibronectin or vitronectin. The overall action mechanism is still not completely clear, but some studies have associated it to the conformation of the guanidine side group of arginine and its distance and angle from the acidic pendant of aspartic acid. Modification of chemical structures in order to include an RGD or RGD-like group has been proposed for a number of applications where interaction with cells is desired, to enhance adhesion or recognition by cellular receptors.


				
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