Search results for "Biomaterial"
showing 10 items of 1350 documents
Hardening of bio-silica in sponge spicules involves an aging process after its enzymatic polycondensation: evidence for an aquaporin-mediated water a…
2011
Abstract Background Spicules, the siliceous skeletal elements of the siliceous sponges, are synthesized enzymatically via silicatein. The product formed, bio-silica, constitutes their inorganic matrix. It remained unexplored which reactions are involved in molding of the amorphous bio-silica and formation of a solid and rigid biomaterial. Methods Cell and molecular biological techniques have been applied to analyze processes resulting in the hardening of the enzymatically synthesized bio-silica. The demosponge Suberites domuncula has been used for the studies. Results Cell aggregates (primmorphs) from the sponge S . domuncula , grown in the presence of Mn-sulfate, form spicules that compris…
Self-assembly of a bioelastomeric structure: solution dynamics and the spinodal and coacervation lines.
1990
The stability, metastability, and instability regions of aqueous solutions of a representative synthetic bioelastomeric polymer, poly (Val-Pro-Gly-Val-Gly), were determined by a combined use of elastic and quasi-elastic light scattering experiments. The approach followed here offers the attractive advantage of singling out the relevant contributions to the total scattering even in the presence of traces of noninteracting larger sized impurities. Conclusions so reached were checked by means of independent experiments. The present results provide descriptions of the very early events in the physics of bioelastogenesis in terms of general polymer science and phase transitions, and in terms of …
Polyester vascular prostheses coated with a cyclodextrin polymer and activated with antibiotics: Cytotoxicity and microbiological evaluation
2008
Abstract Polyester (PET) vascular grafts are used to replace or bypass damaged arteries. To minimize the risk of infection during and after surgical interventions, a PET vascular prosthesis (Polythese®) was functionalized with cyclodextrin polymers (PolyCDs) in order to obtain the controlled release of antibiotics (ABs: ciprofloxacin, vancomcyin and rifampicin). An epithelial cell line (L132) was used to determine the viability of the antibiotics, and human pulmonary microvascular endothelial cells (HPMEC) were used for cell proliferation by cell counting and cell vitality with Alamar Blue fluorescent dye. Staphylococcus aureus, Escherichia coli and Enteroccocus sp. were used to determine t…
Hydroxypropylcellulose as a novel green reservoir for the synthesis, stabilization, and storage of silver nanoparticles
2015
Muhammad Ajaz Hussain,1 Abdullah Shah,1 Ibrahim Jantan,2 Muhammad Raza Shah,3 Muhammad Nawaz Tahir,4 Riaz Ahmad,5 Syed Nasir Abbas Bukhari2 1Department of Chemistry, University of Sargodha, Sargodha, Pakistan; 2Drug and Herbal Research Centre, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, Kuala Lumpur, Malaysia; 3International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan; 4Institute of Inorganic and Analytical Chemistry, Johannes Guttenberg University, Duesbergweg, Mainz, Germany; 5Centre for Advanced Studies in Physics (CASP), GC University, Lahore, Pakistan Abstract: Polysaccharides are attracting the vigil eye of…
Application of the theory of naturally curved and twisted bars to designing Gorlov's helical turbine 1. System of governing equations
1998
The method of designing a new type of turbine used in flows of various kinds is discussed. Static, kinematic, and constitutive equations for transversely isotropic naturally curved and twisted bars are given, and the hypotheses used are discussed. The statement of the problem is linear and corresponds to small displacements. A method for solving the statically indeterminate problem is proposed. The objectives of numerical calculations, which will comprise the content of the second part of the investigation, are formulated.
Bioresponsive poly(amidoamine)s designed for intracellular protein delivery.
2013
Poly(amidoamine)s with bioreducible disulfide linkages in the main chain (SS-PAAs) and pH-responsive, negatively charged citraconate groups in the sidechain have been designed for effective intracellular delivery and release of proteins with a net positive charge at neutral pH. Using lysozyme as a cationic model protein these water soluble polymers efficiently self-assemble into nanocomplexes by charge attraction. At pH 5 (the endosomal pH) the amide linkages connecting the citraconate groups in the sidechains of the SS-PAAs are hydrolyzed by intramolecular catalysis, resulting in expulsion of the negative citraconate groups and formation of protonated amine groups, resulting in charge reve…
Two dimensional self-assembly of bis-acylureas having various functional end groups.
2011
We present the synthesis and morphology study of thirteen bis-acylurea molecules with various functional end groups. The bis-acylureas have two acylurea groups, -NH-CO-NH-CO-, divided by a pentamethylene spacer, -(CH(2))(5)-, and two symmetric functional end groups, such as, aliphatic, benzyl, mono- and bi-thiophenyl, sulfur-containing, and propargyl (HC[triple bond]CCH(2)-) moieties. The bis-acylureas were synthesized by the coupling reactions of ureas with pimeloyl chloride or pimelic acid. Upon cooling from hot isotropic solutions, the bis-acylureas spontaneously form supermolecules. In the cases of aliphatic, benzyl, mono- and bi-thiophenyl functional groups, two dimensional supramolecu…
Mononuclear rearrangement of heterocycles in zwitterionic micelles of amine oxide surfactants.
2012
Abstract Rate constants for the mononuclear rearrangement (MRH) of Z -phenylhydrazones of some 5-substituted-3-benzoyl-1,2,4-oxadiazoles in water have been measured in the presence of zwitterionic micelles. The use of micellized N -tetradecyl- N , N -dimethylamineoxide (C 14 DMAO) as the reaction medium allowed to solubilize the otherwise water-insoluble oxadiazoles. Micellar rate effects were analyzed by using a simple pseudo-phase model and compared with those obtained in non-ionic micelles (Triton X-100). Evidence that both the rate of the rearrangement reaction and the binding of the substrates to the micelles are mainly governed by substrate hydrophobicity is obtained. The disagreement…
Comparison of linear and hyperbranched polyether lipids for liposome shielding by 18F-radiolabeling and positron emission tomography
2018
Multifunctional and highly biocompatible polyether structures play a key role in shielding liposomes from degradation in the bloodstream, providing also multiple functional groups for further attachment of targeting moieties. In this work hyperbranched polyglycerol (hbPG) bearing lipids with long alkyl chain anchor are evaluated with respect to steric stabilization of liposomes. The branched polyether lipids possess a hydrophobic bis(hexadecyl)glycerol membrane anchor for the liposomal membrane. hbPG was chosen as a multifunctional alternative to PEG, enabling the eventual linkage of multiple targeting vectors. Different hbPG lipids (Mn = 2900 and 5200 g mol-1) were examined. A linear bis(h…
Formation of protein multilayers and their competitive replacement based on self-assembled biotinylated phospholipids.
1994
Based on specific recognition processes the build-up of protein multilayers was achieved using streptavidin layers as a docking matrix. For this purpose, streptavidin was organized at biotin-containing monolayers, liposomes, and self-assembled layers on gold. Thus, mixed double and triple layers of streptavidin, Con A, Fab fragments, and hormones were prepared and characterized by fluorescence microscopy and plasmon spectroscopy. Using biotin analogues with lower binding constants several cycles of multilayer formation followed by competitive replacement could be achieved.