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Abstract
The second half of the 20th century has witnessed a productive interplay between chemistry and materials science—in fields as varied as polymers, catalysis, interface science, ceramics, and electronic materials. Society also has enjoyed the spectacular results-most notably in information and communications technologies—achieved by merging condensed matter physics and materials research. In contrast, connections between materials science and biology have been relatively weak. To be sure, materials research has made important contributions to medicine, but the discipline has yet to draw on biology in the same way that it has absorbed people, ideas, and skills from chemistry and physics.
This is beginning to change. With increasing frequency, new materials or processing strategies are emerging, inspired by biological examples or developed directly from biological systems. Already, researchers are engineering bacteria or other organisms to synthesize monomers for polymer production. They are synthesizing and expressing artificial genes to produce proteinlike materials with the mechanical properties of silk, collagen, or other materials containing elastic fibers. They are beginning to use phospholipids as templates for electronic materials; make synthetic phospholipid vesicles that, like proteins, respond to signals; use stereoselective catalyses to produce optically active polymers from racernic starting materials; and develop protein- and lipid-based sensors.
Chemists are playing a vital role in these developments, providing synthetic skills as well as insights into the behavior of complex molecular systems.
... Also, the involved biological process does not require any high temperature conditions and hazardous precursors which could create environmentally friendly biosensing medium. [6][7][8] Particularly, the binding affinities in serum albumin can extend conjugation towards other molecules due to its hydrophobic, hydrogen bonding and electrostatic interactions. 9,10 In general, the amino acid chiral subunits in protein molecule possess the stereospecific behavior that can cause binding with other small molecules. ...
... 19 In addition, the structural changes in protein can create defects in surface and thus altered properties tend to provide amplification in signal transduction. 6 Herein, we anticipate that the available sugar molecules, thymine and phosphate groups in DNA based sensor resulting amplified signal detection. ...
Bovine serum albumin (BSA) emerged as a potential bioprotein in the sensing field. Understanding the interactions of BSA with the analyte biomolecule has not been much reported. Herein, we report the functionally modified BSA (f-BSA) and its consecutive adsorption onto DNA for the ultrasensitive protein sensing. The DNA-modified f-BSA (DNA@f-BSA) composite was further characterized by using scanning electron microscopy, X-ray diffraction, and Fourier transform-infrared spectroscopy. Obtained results demonstrated excellent composite formulation due to electrostatic interaction/binding intercalation and provided promising scaffold for protein biosensor. The as-prepared DNA modified f-BSA (DNA@f-BSA) based biocomposite can be used as a selective probe for the detection of BSA by recording square wave voltammetry signals. The sensitivity of the hybrid biosensor significantly improved the BSA detection over a wide concentration range from 1×10-20 g/mL to 1×10-4 g/mL with a detection limit of 2.18×10-21 g/mL. Thus, the results have revealed the promising biosensor interactions which pave the way for the sensitive protein detection.
Herein, a novel nanostructure based on cyclic aromatic polyimide with statistical star polymer structure was synthesized via the functionalization of the CuFe2O4 MNPs surface. The polymerization process on the functionalized surface of CuFe2O4 MNPs was performed with pyromellitic dianhydride and phenylenediamine derivatives. All analytical methods such as Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric (TG) analysis, X-ray diffraction (XRD) pattern, energy-dispersive X-ray (EDX), field-emission scanning electron microscope (FE-SEM), vibrating-sample magnetometer (VSM) were performed to characterize the structure of CuFe2O4@SiO2-polymer nanomagnetic. The cytotoxicity of CuFe2O4@SiO2-Polymer was investigated for biomedical application by MTT test. The results proved that this nanocmposite was biocompatible with HEK293T healthy cells. Also, the evaluation antibacterial property of CuFe2O4@SiO2-Polymer showed that its MIC in Gram-negative and Gram-positive bacteria were 500–1000 µg/mL, so it had antibacterial activity.
The design and development of tissue-engineered products have benefited from the clinical utilization of a wide range of biodegradable polymers. Newly developed biodegradable polymers and modifications of previously developed biodegradable polymers have enhanced the tools available for tissue-engineering applications. Insights gained from studies of cell–matrix interactions, cell–cell signaling, and organization of cellular components are placing increased demands on medical implants to interact with the patient’s tissues in a more biologically suitable fashion. Whereas, in the 20th century, biocompatibility was largely equated with eliciting no harmful response, the biomaterials of the 21st century will have to elicit tissue responses that support healing or regeneration of the patient’s own tissues.
This chapter surveys the universe of biodegradable polymers that may be useful in the development of medical implants and tissue-engineered products. Here, we distinguish between biologically derived and synthetic polymers. The materials are described in terms of their chemical composition, breakdown products, mechanism of breakdown, mechanical properties, and clinical limitations. Also discussed are the product design considerations for processing biomaterials into a final form (e.g., gel, membrane, and matrix) that will induce the desired tissue response.
With the advancement of polymer engineering, complex star-shaped polymer architectures can be synthesized with ease, bringing about a host of unique properties and applications. The polymer arms can be functionalized with different chemical groups to fine-tune the response behavior or be endowed with targeting ligands or stimuli responsive moieties to control its physicochemical behavior and self-organization in solution. Rheological properties of these solutions can be modulated, which also facilitates the control of the diffusion of the drug from these star-based nanocarriers. However, these star-shaped polymers designed for drug delivery are still in a very early stage of development. Due to the sheer diversity of macromolecules that can take on the star architectures and the various combinations of functional groups that can be cross-linked together, there remain many structure–property relationships which have yet to be fully established. This review aims to provide an introductory perspective on the basic synthetic methods of star-shaped polymers, the properties which can be controlled by the unique architecture, and also recent advances in drug delivery applications related to these star candidates.
The design and development of tissue-engineered products has benefited from many years of clinical utilization of a wide range of biodegradable polymers. Newly developed biodegradable polymers and modifications of previously developed biodegradable polymers have enhanced the tools available for creating clinically important tissue-engineering applications. Insights gained from studies of cell-matrix interactions, cell-cell signaling, and organization of cellular components, are placing increased demands on medical implants to interact with the patient's tissue in a more biologically appropriate fashion. Whereas in the twentieth century biocompatibility was largely equated with eliciting no harmful response, the biomaterials of the twenty first century will have to elicit tissue responses that support healing or regeneration of the patient's own tissue.This chapter surveys the universe of those biodegradable polymers that may be useful in the development of medical implants and tissue-engineered products. Here, we distinguish between biologically derived polymers and synthetic polymers. The materials are described in terms of their chemical composition, breakdown products, mechanism of breakdown, mechanical properties, and clinical limitations. Also discussed are product design considerations in processing of biomaterials into a final form (e.g., gel, membrane, matrix) that will effect the desired tissue response.
Major advances in modern materials science focus in the preparation of bioconjugates combining synthetic polymers with biological macromolecules such as peptides, proteins, polysaccharides, and oligonucleotides. The use of such systems in biomedical applications requires that the bioconjugates are of uniform size and composition and water compatible. Recent advances in polymer chemistry and a broad range of orthogonal methods, including controlled/“living” polymerization techniques as well as conjugation/activation chemistries, have been employed to prepare polymer-biomolecule hybrids of controlled structure and specific functionalities. This chapter gives a general overview on the design of nanoparticulate bioconjugates, and the orthogonal chemistries used for their materialization. The bioconjugates discussed are: polymer-protein nanoparticulates, polymer-ODN/DNA nanoparticulates, polymer-carbohydrate nanoparticulates, polymer-bioactive molecule nanoparticulates, polymer-drug nanoparticulates and polymer-imaging agent nanoparticulates. Nanoparticulate materials of interest include micelles, nanogels, dendrimers, liposomes and polymersomes, and viral capsids associated with one or more biologically relevant molecules at the interface to give a nanoparticulate bioconjugate.
A batch of linear [m,n]-type sugar-based polyureas was synthesized by polyaddition reaction in solution from hexamethylene diisocyanate or 4,4’-methylene-bis(phenyl isocyanate) with the acyclic 2,3,4-tri-O-methyl-1,5-diamino-alditols having L-arabino,
or xylo configuration or the bicyclic 1,6-diamino-1,6-dideoxy-2,4:3,5-di-O-methylene-D-glucitol. The polymers were obtained in good yields and fair molecular weights. All these polyureas were semicrystalline materials showing well-defined melting transition
within the 86−171°C range, with Tgs being dependent on the aliphatic or aromatic nature of the diisocyanate used, and on the cyclic or acyclic chemical structure of the sugar moiety. They were found to be stable up to around 240°C, decomposing
at higher temperatures through a one- or two-stage mechanism.
Well-defined peptide-poly(epsilon-caprolactone) (Pep-PCL) biohybrids were successfully synthesized by grafting-from ring-opening polymerization (ROP) of epsilon-caprolactone (CL) using designed amine-terminated sequence-defined peptides as macroinitiators. MALDI-TOF-MS and H-1 NMR analyses confirmed the successful attachment of peptide to the PCL chain. The gel permeation chromatography (GPC) measurement showed that the Pep-PCL biohybrids with controllable molecular weights and low polydispersities (PDI <1.5) were obtained by this approach. The aggregation of Pep-PCL hybrid molecules in THF solution resulted in the formation of micro/nanospheres as confirmed through FESEM, TEM, and DLS analyses. The circular dichroism study revealed that the secondary structure of peptide moiety was changed in the peptide-PCL biohybrids. The crystallization and melting behavior of Pep-PCL hybrids were somewhat changed compared with that of neat PCL of comparable molecular weight as revealed by DSC and XRD measurements. In Pep-PCL biohybrids, extinction rings were observed in the PCL spherulites, in contrast with the normal spherulite morphology of the neat PCL. There was a substantial decrease (4-5 folds) in the spherulitic growth rate after the incorporation of peptide moiety at the end of PCL chain as measured by polarizing optical microscopy. Pseudomonas lipase catalyzed enzymatic degradation was studied for Pep-PCL hybrids and neat PCL. (C) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 50: 2130-2141, 2012
Effect of curing temperature on properties of ovalbumin has been investigated. Functional basis, crosslinking degree, tensile strength, and hardness increases with rising curing temperature. The increase of visible transmittance and the decrease of absorption accompany with increasing wavelength. The absorptive peak shows at 440–450 nm and the wavelength of the absorptive peak increases with the rising curing temperature. The relationship of joint strength with solvent welded joints of ovalbumin to their microstructure is also investigated. Ovalbumin can promote joint strength after the treatment of distilled water and curing. Comparing joint strength with fracture morphology, the smoother fracture surface morphology is related to the maximum tensile and shear joint strength, respectively. The joint strength is increasing with curing temperature and compressive stress, and the joint strength of treatment with 150°C curing temperature and 0.12 kgf/mm2 compressive stresses are larger than its original tensile fracture strength of cured ovalbumin at same curing temperature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
We imagine the built environment of the future as a 'bio-hybrid machine for living in' that will sense and react to activities within the space in order to provide experiences and services that will elevate quality of life while coexisting seamlessly with humans and the natural environment. The study of Hierarchical design in biological materials has the potential to alter the way designers/ engineers/ craftsmen of the future engage with materials in order to realise such visions. We are exploring this design approach using digital manufacturing technologies such as jacquard weaving and 3D printing.
Two novel sugar-based fatty ester polyols were synthesized by selective transesterification of epoxidized methyl or ethyl oleate with unprotected methyl α-D-glucopyranoside and sucrose respectively, followed by hydrolysis of the epoxide moiety. The so-formed polyols were then used as polyurethane (PU) precursors in the polyaddition with isophorone diisocyanate (IPDI) in the presence of dibutyl tin dilaurate (DBTDL) as a catalyst. Interestingly, the reactivity of the hydroxyl functions attached to the sugar and to the fatty ester chain moieties respectively could be discriminated with respect to the solvent used, enabling the synthesis of either linear or cross-linked PUs. The linear PUs were studied by means of FTIR, 1H NMR spectroscopy and size exclusion chromatography, SEC. The thermo-mechanical properties of these original PUs bearing pendant or intramolecular sugar units were also analyzed by differential scanning calorimetry, DSC.
SUMMARY Systems with parts in relative motion experience friction and wear. The need to understand tribology on the micro- and nanoscale increases in importance with decreasing technological device sizes. Micro- and nanoelectromechanical systems often experience failure due to stiction (static friction). During millions of years of evolution, natural systems have optimized their tribological and other performances. The aim of biotribology is to gather information about friction, adhesion, lubrication and wear of biological friction systems and to apply this knowledge to innovate technology, with the additional benefit of environmental soundness. Examples for biological friction systems at different length scales are bacterial flagellae, joints and articular cartilage as well as muscle connective tissues. Our model system for biotribological investigations at the micro- and nanoscale are diatoms. Diatoms are single celled microalgae with a cell wall consisting of amorphous glass enveloped by an organic layer. Diatoms are small, highly reproductive, and accessible with different kinds of microscopy methods. There are several diatom species which actively move (e.g. Bacillaria paxillifer forms colonies of 5 to 30 cells which rhythmically expand and contract) or which can - as cell colonies - reversibly be elongated by a major fraction of their original length (e.g. Ellerbeckia arenaria). Diatoms also seem to show highly efficient self lubrication while cells divide and grow. These algae might provide lubrication strategies which are still unknown to engineers!
Novel linear homogeneous polyurethanes and polyureas with enhanced hydrophilic character have been successfully prepared from sugar-based monomers having their hydroxyl groups free or partially protected. By the reaction of primary hydroxyl groups of xylitol with dimethyl hexamethylene dicarbamate (HMDC) or di-tert-butyl-4,4′-diphenyl methyl dicarbamate (MDC), two new linear semicrystalline polyurethanes [PU(X-HMDC) and PU(X-MDC)] have been prepared. Likewise, by the reaction of xylitol with the analogous diisocyanates hexamethylene diisocyanate (HMDI) or 4,4′-methylenebis(phenyl isocyanate) (MDI), similar polyurethanes [PU(X-HMDI) and PU(X-MDI)] were obtained. However, these latter polyurethanes present some degree of crosslinking because of the higher reactivity of the diisocyanate comonomers. Linear hydrophilic polyureas having free hydroxyl groups joined to the main chain have also been prepared by the reaction of the same diisocyanates (HMDI and MDI) with 1,6-diamino-1,6-dideoxy-D-mannitol and 1,6-diamino-1,6-dideoxy-3:4-O-isopropylidene-D-mannitol. As far as we are aware, this kind of polyhydroxylated polyurea has not been previously described in the literature. The new polymers were characterized by standard methods (elemental analyses, gel permeation chromatography, IR, and NMR). The polyurethanes were hydrolytically degradable under physiological conditions, in contrast with less-hydrophilic linear polyurethanes previously described. The thermal properties of the novel polymers were investigated by thermogravimetric analysis and differential scanning calorimetry. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Peptide polymer hybrid bioconjugates containing poly(methyl methacrylate) chains attached with oligopeptide molecules were prepared by atom transfer radical polymerization (ATRP) using designed peptide-initiators. These initiators were synthesized from newly designed peptides with 2-bromoisobutyric acid via a standard coupling reaction. ATRP of methyl methacrylate was conducted using Br-terminated peptide as macroinitiator and copper(I) chloride/N,N,N',N '',N ''-pentamethyldiethylenetriamine as the catalyst system in dimethyl sulfoxide (DMSO) at an elevated temperature (90 degrees C). The peptide polymer bioconjugates with controllable molecular weights and low polydispersities (PDI < 1.35) were obtained. We devised a simple solution approach in assembling the peptide polymer bioconjugate molecules into hybrid micro/nanospheres in different organic solvents as confirmed from transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), and dynamic light scattering (DES) results. The average size of the formed hybrid micro/nanospheres decreases with the increase of the polarity of the solvent used in aggregation process. A mechanistic model was suggested for the aggregation of peptide polymer conjugates into hybrid micro/nanospheres that correlates well with the experimental observation. The dye-loaded hybrid micro/nanospheres were simply prepared by mixing an organic dye (Rhodamine 6G) into the aggregated solution of peptide-polymer bioconjugates. The uptake of dye into the micro/nanospheres was studied by fluorescence microscopy and time-correlated single photon counting (TCSPC) techniques.
A study was conducted to demonstrate the derivation of dendrimers from 1→3 branching motifs. A three-atom distance was needed between the branch point and the reactive chemical center to circumvent retardation of these chemical transformations. Triol was treated with the chloroacetic acid, esterified (MeOH,H+ to produce polyester reduced (LAH) and transformed (TsCl) to the corresponding tris(tosylate). The simplest 1→3 branched monomer TRIS had been used for simple amidation where it readily transformed esters to the corresponding amide by a facile two-step procedure, transesterification followed by rearrangement. This ester triol transformation was also demonstrated in the conversion of numerous initially nondendritic hydrophobic materials into more hydrophilic compounds, such as neutral, cyclophanedodecaalcohol.
The study of the self-assembly of helical structures has been motivated by their newly found biological and technological importance. In many systems, helical ribbons are precursors to the formation of tubules, which may be used in the controlled release of drugs or as templates for micron scale electronic components. Used as springs, helical ribbons open up an entirely new avenue for the measurement of forces on the biological scale. Given the importance of these structures, a series of experiments to probe the kinetics and energetics of helix formation has been performed. Theoretical interpretation and experimental measurements of helix elastic properties have also been performed. It was shown that the formation of helical ribbons of pitch angles of 11 and 54ʻ, previously thought to be a property unique to model bile systems, is a general phenomenon of quaternary sterol systems composed of a bile salt or nonionic detergent, a phosphatidylcholine or a (mixture of) fatty acid(s), and a steroid analog of cholesterol in water. The majority of helical ribbons were right-handed; but some left-handed helices have been found. Additionally, a small number of helices with pitch angles between 30 and 47ʻ were found in some systems. The elastic properties of the low pitch helical ribbons in Chemically Defined Lipid Concentrate were studied via relaxation experiments and measurements of force versus extension curves using silicon cantilevers as force probe. The helices exhibited linear behavior over a large range of extensions (up to 200% of helix original axial length). The forces involved in the deformation of low pitch helices have been found to be in the 0.25-1.0 nN range making them ideal for use as biological force probes.
A study was initiated into the formation and stability of highly soluble beta-sheet macrostructures. Such beta-sheet macrostructures are useful model systems for the study of the biological function of the hydrophobic core of proteins and for the de novo design of novel catalytic mimics. In the current study, a 16-mer-alanine-based peptide (Ac-KA14K-NH2) that is highly water soluble and adopts an extremely stable macromolecular beta-sheet structure was synthesized. A tyrosine-containing analog (Ac-KYA13K-NH1) was used to study the tertiary structure of the complex by circular dichroism spectroscopy, while the influence of the charges on the complex formation and binding affinity was evaluated using a zwitterionic analog (Ac-KEA13KE-NH1). Both the secondary and tertiary structures of the beta-sheet complex were stable to denaturants, as demonstrated by far- and near-ultraviolet circular dichroism spectroscopy. Binding studies with mononucleotides have shown that the beta-sheet complex binds to molecules through both hydrophobic and electrostatic interactions. These intrinsic properties were found to be a prerequisite for the observed enhanced cleavage of phosphodiester bonds.
Hydrogels are cross-linked hydrophilic polymers that can imbibe water or biological fluids. Their biomedical and pharmaceutical applications include a very wide range of systems and processes that utilize several molecular design characteristics. This review discusses the molecular structure, dynamic behavior, and structural modifications of hydrogels as well as the various applications of these biohydrogels. Recent advances in the preparation of three-dimensional structures with exact chain conformations, as well as tethering of functional groups, allow for the preparation of promising new hydrogels. Meanwhile, intelligent biohydrogels with pH- or temperature-sensitivity continue to be important materials in medical applications.
Synthetic polymers and gels capable of molecular recognition are very useful in designing novel intelligent biomaterials. In this article we review the recent progress in both theoretical and experimental studies toward making heteropolymers and gels with biomimetic properties, specifically in relation to protein recognition. Knowledge obtained from protein-folding studies sheds much light on our understanding of the heteropolymer behavior. Consequently, it is possible to design synthetic heteropolymers with specific structure that can fold into unique conformations, form receptor-like cavities and recognize specific target molecules. Recent studies towards simplifying the requirement for the heteropolymer structures and the polymerization procedures are reviewed. Intelligent polymer gels can be designed with new and interesting characteristics of molecular imprinting. The results are encouraging for further investigation and design of synthetic gels with programmable collapsed structure might be achieved.
Spiders spin up to seven different types of silk and each type possesses different mechanical properties. The reports on base sequences of spider silk protein genes have gained importance as the mechanical properties of silk fibers have been revealed. This review aims to link recent molecular data, often translated into amino acid sequences and predicted three dimensional structural motifs, to known mechanical properties.
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