Biosensors Based On Biological Nanostructures-Books Pdf

Biosensors Based on Biological Nanostructures
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150 New Perspectives in Biosensors Technology and Applications. facilitated the study of biological systems which can be utilized in biosensor devices. catalytic activities and molecular recognition Thus the challenge for synthetic chemistry in. the area of molecular electronics is to prepare molecules with specific and well defined. functions i e that can be used at a molecular level as wires switches diodes etc The. controlled assemblies of supramolecular species selected components allow the preparation. of nanosize materials with quite sophisticated electronic properties De La Rica e Matsui. 1 1 Peptide based nanostructures, The formation of tubular peptide nanostructures has been performed using several different. peptide sequences such as heptapeptide CH3CO Lys Leu Val Phe Phe Ala Glu NH2 Lu. Jacob et al 2003 and dipeptides NH3 Phg Phg COO Reches e Gazit 2004 and NH3 Phe. Trp COO Reches e Gazit 2003 The first peptide nanotubes were obtained by M R. Ghadiri and co workers from cyclic compounds Ghadiri Granja et al 1993 The L amino. acids are the most used building blocks However D amino acids can also self assemble to. form nanofibers similar to those obtained from L amino acids Poteau e Trinquier 2005. The properties of peptides can be modified through changes in the sequence of amino acid. residues used in their preparation providing a highly relevant factor in building these new. systems Poteau e Trinquier 2005 Such changes were reported in a study by varying the D. amino acids D Alanine D Leucine and D phenylanine to obtain different peptide. nanotubes De Santis Morosetti et al 2007 It was observed that by employing enantiomers. D L the possibility of obtaining different supramolecular systems arises with possible. changes in their structural and electronic properties De Santis Morosetti et al 2007. One of the most commonly used peptides in synthesis of nanotubes is NH3 Phe Phe COO. These nanotubes exhibit several unique properties such as high uniformity along the entire. length of the tube biocompatibility stability against various solvents and thermal stability. In this sense there are several studies that investigate the structural control of the nanotubes. by changing variables such as temperature solvent and pH Adler Abramovich Reches et. al 2006 The NH3 Phe Phe COO nanotubes maintain their morphology up to 200 C and. 2010 The thermal stability has been attributed to stacking interactions among aromatic. total degradation or loss of tubular morphology occurs between 200 and 300 C Ryu e Park. residues that mediate the formation of structures Reches e Gazit 2003 The investigation of. stability in different organic solvents shows that the nanotubes do not suffer morphological. changes after treatment in ethanol methanol 2 propanol acetone and acetonitrile Adler. Abramovich Reches et al 2006, Moreover in addition to conformational changes and the sequences of amino acids used in. peptide synthesis of nanomaterials cyclical or linear the amount of amino acids used and. the functional group of the side chains can influence the formation and possibly the desired. application Brea Castedo et al 2007 In this case all the proposed changes and the. preparation methods are in early stages of study and require further research to better. understand their formation and their influence on structural and electronic properties. Yanlian Ulung et al 2009, 2 Preparation methods of peptide nanostructures. 2 1 Obtaining nanostructures in liquid phase, The liquid phase method for obtaining nanostructures is divided in two steps To obtain a. nanostructure based on NH3 Phe Phe COO for example the first step is the dissolution. www intechopen com, Biosensors Based on Biological Nanostructures 151.
of the compound in an organic solvent 1 1 1 3 3 3 hexafluoro 2 propanol HFP at a. concentration of 100mg mL 1 In the second step nanostructures are obtained in a. spontaneous process after the dilution in water to achieve 2mg mL 1 of concentration By. this protocol NH3 Phe Phe COO self assemble as nanotubes of 80 to 300 nm thick. understood However the most acceptable explanation suggests that the stacking. The self assembling mechanism in which nanotubes are produced is not yet fully. interactions and hydrogen bonds between aromatic rings are responsible for the material. nano organization Reches e Gazit 2003, Another strategy to obtain these materials in liquid phase was proposed by Kim et al Kim. Han et al 2010 In this work the authors used only pure water as solvent and submitted. the system to heating and sonication to dissolve the peptide since NH3 Phe Phe COO. present hydrophobic characteristics and do not dissolve easily in water Nanostructures are. formed after cooling pH values of the preparing media The concentration of the dipeptide. solution was susceptible to variation by the authors in order to comprehend their role in. nanostructure formation Their results showed formation of NH3 Phe Phe COO nanowires. in alkaline media while nanotubes were formed in acidic media Also at high. concentrations of peptide the predominant nanostructures formed are nanowires while at. low concentrations nanotubes are prevalent, 2 2 Nanostructure preparation in solid vapor phase. Peptide nanostructures have been prepared by self assembly oriented in the solid vapor. phase method which consists of using two solvents one to solubilize the peptide and. another one to encourage the nanostructure assemble Based on the bottom up strategy the. first step consists on the formation of a peptide film onto substrate surface usually silicon. with posterior evaporation of the solvent in the absence of humidity In this case the. peptide film is referred to as the solid phase The next step consists of keeping the solid film. in a vapor solvent atmosphere the commonly called vapor phase Parameters like. temperature vapor pressure concentration of solid film and exposure time of the film to. vapor solvent govern the nanostructure formation, Ryu et al described this methodology as the one to obtain 1D nanostructures Ryu e Park. 2008b a The authors studied the influence of temperature and water activity of a solution. containing metallic salts in the nanostructures formation and they reported that. nanostructures are formed at high water activity while for activity values lower than 0 3 no. nanostructures were obtained Also it was observed that nanostructures were only achieved. at a working temperature of 100 to 150 C Fig 1 shows the experimental schematic process. to prepare nanowires or nanotubes in solid vapor phase. The role of the solvent in this process was adapted by Demirel at al Demirel Malvadkar et. al 2010 with a few adaptations During this study the concentration of the precursor. solution was controlled at 2mg mL 1 and the solvent needed at the second step of the solid. vapor process was changed Results show that the nanostructure morphology is related to. the dielectric constant values of the solvents For example results showed that when formed. on water which presents a dielectric constant of 80 1 a tubular structure is obtained Same. structure are obtained when using methanol dielectric constant of 32 6 or ethanol 24 3 as. solvents while solvents presenting dielectric constants much smaller such as toluene 2 4. chloroform 4 8 or tetrahydrofuran 7 5 do not permit the peptide self assembling and no. structure is obtained Scanning electronic micrographs SEM of the nanostructure obtained. at various solvents are shown in Fig 2, www intechopen com. 152 New Perspectives in Biosensors Technology and Applications. Fig 1 Experimental scheme of obtaining peptide nanostructure using solid vapor process. Reprinted with permission from Ryu J and C B Park 2010 High Stability of Self. Assembled Peptide Nanowires Against Thermal Chemical and Proteolytic Attacks. Biotechnology and Bioengineering 105 2 221 230 2010 Wiley Ltd. Fig 2 SEM images of NH3 Phe Phe COO tubes and vesicles a 2mg mL dipeptide in. ethanol vaporized at 25 C b 2mg mL dipeptide in acetone vaporized at 25 C c 2mg mL. dipeptide in ethanol vaporized at 80 C and d 2mg mL dipeptide in acetone vaporized at. 80 C Reprinted with permission from Demirel G N Malvadkar et al 2010 Control of. Protein Adsorption onto Core Shell Tubular and Vesicular Structures of Diphenylalanine. Parylene Langmuir 26 3 1460 1463 2010 American Chemical Society Ltd. www intechopen com, Biosensors Based on Biological Nanostructures 153.
2 3 Obtaining nanostructures for physical vapor deposition. Recently NH3 Phe Phe COO nanotubes were obtained vertically oriented employing the. physical vapor deposition technique Fig 3 Adler Abramovich Aronov et al 2009 Size. and quantity of peptide nanotubes were controlled through deposition parameters. adjustment such as time solvent of preparation temperature and distance between. substrates The peptide nanotubes formation using this technique became possible because. of the low molecular weight and high volatility of precursor species In a typical synthesis. the NH3 Phe Phe COO is heated at 220 C in a vacuum chamber containing a clean. substrate heated at 80 C that is located at the top of the chamber The nanotubes formed. exhibit length of hundreds of micrometers and diameters of 50 to 300nm with morphologies. similar to those from the liquid phase This method has been employed in the fabrication of. electronic devices such as capacitors but it can be used in the modification of electrodes for. electrochemical uses, Fig 3 Proposed assembly mechanism for the formation of vertically aligned ADNTs. a Schematic of the vapor deposition technique During evaporation the NH3 Phe Phe COO. peptide which is heated to 220 C attained a cyclic structure Cyclo NH3 Phe Phe COO. and then assembled on a substrate to form ordered vertically aligned nanotubes b Illustration. of a single peptide nanotube composed mainly of peptide Cyclo NH3 Phe Phe COO. c Molecular arrangement of six Cyclo NH3 Phe Phe COO peptides after energy. minimization A stacking interaction between aromatic moieties of the peptides is suggested. to provide the energetic contribution as well as order and directionality for the initial. interaction Reprinted with permission from Shklovsky J P Beker et al 2010 Bioinspired. peptide nanotubes Deposition technology and physical properties Materials Science and. Engineering B Advanced Functional Solid State Materials 169 1 3 62 66 2009 Elsevier B V. In a recently work this technique was used together with photolithography to enable. peptide nanotubes to assume specific positions in a silicon wafer Shklovsky Beker et al. 2010 The authors used a photoresist wafer with square shaped cavities The schematic. process for the cavities preparation is in Fig 4 According to SEM images presented in Fig 4. dipeptide nanotubes are located over the silicon wafer which is useful to construct. integrated circuits since the orientation and control of nanotubes material size is needed in. such systems, www intechopen com, 154 New Perspectives in Biosensors Technology and Applications. Fig 4 Left Schematic diagram of the peptide nanotubes bundles fabrication process. Right SEM images of patterned arrays of peptide nanotubes fabricated by PVD a Cross. section view of patterned substrate covered by peptide nanotube coating b Top view of. patterned substrate covered by peptide nanotube coating c Top view of peptide nanotube. bundles after HF release d Enlargement view of image c Reprinted with permission from. Shklovsky J P Beker et al 2010 Bioinspired peptide nanotubes Deposition technology. and physical properties Materials Science and Engineering B Advanced Functional Solid. State Materials 169 1 3 62 66 2009 Elsevier B V, 2 4 Electrospinning. The electrospinning technique is a technology that uses a high tension electric field 5 50kV. and low currents 0 5 1 A to obtain 1D nanostructures In this process a fluid material is. accelerated and drawn trough an electric field producing structures with reduced diameters. In the work of Singh et al Singh Bittner et al 2008 NH3 Phe Phe COO nanotubes were. prepared from solution in HFP Then this solution was diluted in water to 2 9 mmol L 1 of. concentration and sonicated for 1 hour Variations in the obtaining parameters of the. nanostructures like electric field concentration and flow injection speed on silicon wafer. were investigated and their influence on the nanostructure formation was reported. 3 Functionalization of peptide nanostructures for biosensor applications. In order to obtain some new properties and increase the applicability of peptide. nanomaterials some chemical modification can be performed and materials can be. functionalized to give rise to hybrid compounds Materials that can be employed on. functionalization are nanoparticles polymers and fluorophores among others. Recently Banerjee et al reported the synthesis of peptide nanotubes containing. bis N amido glycylglycine 1 7 heptane dicarboxylate and its modification with. 2 mercaptoethylamine so as to enable its interaction with a Au substrate through a covalent. bond Banerjee Yu et al 2004 In this work the nanomaterial was deposited on a Gold. Au substrate modified with a thiol self assembled monolayer SAM containing cavities. that could be identified by atomic force microscopy AFM AFM images showed that the. modification of the substrate by microfabrication techniques became viable due to the. Biosensors Based on Biological Nanostructures 151 of the compound in an organic solvent 1 1 1 3 3 3 hexafluoro 2 propanol HFP at a concentration of 100mg mL 1 In the second step nanostructures are obtained in a spontaneous process after the dilution in water to achieve 2mg mL 1 of concentration By

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