Material bioactive

Radiation grafting for various biomedical applications remains an extremely active field of development. The grafted side chains can contain functional groups to which bioactive materials can be attached. These include amine, carboxylic, and hydroxyl groups, which can be considered as a center for further modifications. 

Pitt, C. G., Marks, T. A., and Schindler, A., Biodegradable drug delivery systems based on aliphatic polyesters application to contraceptives and narcotic antagonists, in Controlled Release of Bioactive Materials (R. Baker, ed.). Academic Press, New York, 1980, pp. 19-43. 

Kohn, J., and Langer, R., Non-peptide poly(amino acids) for biodegradable drug delivery systems, in Proceedings of the 12th International Symposium on Controlled Release of Bioactive Materials (N. A. Peppas and R. J. Haluska, eds.). Controlled Release Society, Lincolnshire, IL, 1985, pp. 51-52. 

Much remains to be accomplished in the separation, isolation, and identification of both naturally occurring and synthetic bioactive materials effective in the germination of parasitic weed seeds. Structure-activity studies suffer from the lack of separation of isomers in most synthetic samples. Strigol is an important tool in basic studies on the effect of chemicals on seed germination, but it is highly unlikely that the compound will meet practical field... 

A. Trouet, Carriers for bioactive materials, in Polymeric Delivery Systems (R. J. Kostelnik, ed.), Gordon Breach, New York, 1978, p. 157. 

RW Korsmeyer, KD Wilner, WE Ballinger, FC Falkner. Asymmetric membrane tablets for delivery of glipizide. Proceedings of the International Symposium on the Controlled Release of Bioactive Materials, Stockholm, 1997, pp 239-240. 

PI Lee. Determination of diffusion coefficients by sorption from a constant, finite volume. In RW Baker, ed. Controlled Release of Bioactive Materials. New York Academic Press, 1980, pp 255-265. 

The combination of bioactive ceramic particles and a polymer matrix gives bioactive materials which show mechanical properties analogous to those of human cortical bone. However, the bioactivity is not so high because the filler content is limited due to the brittleness, and the weak bonding between the filler and matrix may induce problems. 

It has been shown that the bioactive materials bond to living bone through a hydroxyapatite layer which is formed on their surfaces in the body [13]. Therefore,... 

Kokubo et al. [16,17] showed that the hydroxyapatite formation on the surfaces of bioactive materials in the living body can be reproduced even in an acellular protein-free simulated body fluid (SB F) with ion concentrations nearly equal to those of human blood plasma. This indicates that the hydroxyapatite layer is formed through chemical reaction of the bioactive glass with the surrounding body fluids. The formed layer consists of carbonated hydroxyapatite with small crystallites and low crystallinity, which is similar to bone hydroxyapatite. Hence the bioactivity of a material can be evaluated even in vitro by examining the hydroxyapatite formation on its surface in SBF. 

The bonding mechanism between glass and bone has been described in detail [ 36]. The basis for bone bonding is the reaction of the glass with the surrounding solution. A sequence of interfacial reactions, which begin immediately after the bioactive material is implanted, leads to the formation of a CHA layer and the establishment of an interfacial bonding. The sequence of interfacial reactions can be summarized as follows ... 

Bioactive materials can be used as powders for filling small defects and as coatings that enhance metallic prosthesis fixation. However, when considering bioactive materials for bone regeneration in medium and large defects, bioactive pieces with appropriate mechanical properties are required. At this point, the key is to keep the properties provided by the nanostructure when processing a piece at the macroscopic... 

The design and implementation of a portable fiber-optic cholinesterase biosensor for the detection and determination of pesticides carbaryl and dichlorvos was presented by Andreou81. The sensing bioactive material was a three-layer sandwich. The enzyme cholinesterase was immobilized on the outer layer, consisting of hydrophilic modified polyvinylidenefluoride membrane. The membrane was in contact with an intermediate sol-gel layer that incorporated bromocresol purple, deposited on an inner disk. The sensor operated in a static mode at room temperature and the rate of the inhibited reaction served as an analytical signal. This method was successfully applied to the direct analysis of natural water samples (detection and determination of these pesticides), without sample pretreatment, and since the biosensor setup is fully portable (in a small case), it is suitable for in-field use. 

Olbrich, C., Kayser, O., Muller, R.H., and Grubhofer, N., Solid lipid nanoparticles (SLN) as vaccine adjuvant study in sheep with a mycoplasma bovis antigen and stability testing, International Symposium of Controlled Release and Bioactive Material, 2000, 27, 293-294. 

Other systems like electroporation have no lipids that might help in membrane sealing or fusion for direct transfer of the nucleic acid across membranes they have to generate transient pores, a process where efficiency is usually directly correlated with membrane destruction and cytotoxicity. Alternatively, like for the majority of polymer-based polyplexes, cellular uptake proceeds by clathrin- or caveolin-dependent and related endocytic pathways [152-156]. The polyplexes end up inside endosomes, and the membrane disruption happens in intracellular vesicles. It is noteworthy that several observed uptake processes may not be functional in delivery of bioactive material. Subsequent intracellular obstacles may render a specific pathway into a dead end [151, 154, 156]. With time, endosomal vesicles become slightly acidic (pH 5-6) and finally fuse with and mature into lysosomes. Therefore, polyplexes have to escape into the cytosol to avoid the nucleic acid-degrading lysosomal environment, and to deliver the therapeutic nucleic acid to the active site. Either the carrier polymer or a conjugated endosomolytic domain has to mediate this process [157], which involves local lipid membrane perturbation. Such a lipid membrane interaction could be a toxic event if occurring at the cell surface or mitochondrial membrane. Thus, polymers that show an endosome-specific membrane activity are favorable. 

Bioactive Materials from ROMP Exploring Multivalent Interactions... 

Considering that severe health hazards and diseases that can be induced by the adhesion and proliferation of bacteria on the surface of numerous materials, bioactive materials incorporated in the surfaces will be required. The cellulose-functionalised with porphyrin 69-71 and 80 were shown to kill gram positive and gram negative bacteria upon irradiation with visible light. Such materials could be used in industrial, household and medical environments, and more generaly in areas that would benefit from permanent and efficient surface disinfection.62 64... 

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