Search results for "Biomaterials"
showing 10 items of 1265 documents
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.
Streptavidin-coated TiO2 surfaces are biologically inert: Protein adsorption and osteoblast adhesion studies
2011
Non-fouling TiO2 surfaces are attractive for a wide range of applications such as biosensors and medical devices, where biologically inert surfaces are needed. Typically, this is achieved by controlled surface modifications which prevent protein adsorption. For example, polyethylene glycol (PEG) or PEG-derived polymers have been widely applied to render TiO2 surfaces biologically inert. These surfaces have been further modified in order to achieve specific bio-activation. Therefore, there have been efforts to specifically functionalize TiO2 surfaces with polymers with embedded biotin motives, which can be used to couple streptavidin for further functionalization. As an alternative, here a s…
In vitroandin vivoenhancement of osteogenic capacity in a synthetic BMP-2 derived peptide-coated mineralized collagen composite
2013
Enhancement of osteogenic capacity was achieved in a mineralized collagen composite, nano-hydroxyapatite/collagen (nHAC), by loading with synthetic peptides derived from BMP-2 residues 32-48 (P17-BMP-2). Rabbit marrow stromal cells (MSCs) were used in vitro to study cell biocompatibility, attachment and differentiation on the mineralized collagen composite by a cell counting kit, scanning electron microscopy (SEM) and real-time reversed transcriptase-polymerase chain reaction analysis (RT-PCR). Optimal peptide dosage (1.0 µg/mL) was obtained by RT-PCR analysis in vitro. In addition, the relative expression level of OPN and OCN was significantly upregulated on P17-BMP-2/nHAC compared with nH…
Poly(γ-Glutamic Acid) as an Exogenous Promoter of Chondrogenic Differentiation of Human Mesenchymal Stem/Stromal Cells
2015
Cartilage damage and/or aging effects can cause constant pain, which limits the patient's quality of life. Although different strategies have been proposed to enhance the limited regenerative capacity of cartilage tissue, the full production of native and functional cartilaginous extracellular matrix (ECM) has not yet been achieved. Poly(γ-glutamic acid) (γ-PGA), a naturally occurring polyamino acid, biodegradable into glutamate residues, has been explored for tissue regeneration. In this work, γ-PGA's ability to support the production of cartilaginous ECM by human bone marrow mesenchymal stem/stromal cells (MSCs) and nasal chondrocytes (NCs) was investigated. MSC and NC pellets were cultur…