Biomedical subjects

R Arshady

Publications and source records attributed to R Arshady.

8 recordsLinked to original sources

PubMed1993

Microspheres for biomedical applications: preparation of reactive and labelled microspheres.

This review describes the synthesis and physico-chemical properties of reactive and labelled microspheres useful for biomedical applications. Preparation of microspheres with specific functional groups, fluorescent species, radionuclides and magnetite particles (Fe2O3) are discussed. Physico-chemical properties of microspheres, including surface charge and hydrophilicity/hydrophobicity, are also briefly covered.

Biocompatible Materials↗

PubMed1986

Distribution of polyhexyl cyanoacrylate nanoparticles in nude mice bearing human osteosarcoma.

[14C]Polyhexyl cyanoacrylate nanoparticles (PHCA), with diameters between 200 and 300 nm, were injected intravenously into nude mice bearing a human osteosarcoma. The distribution in liver, spleen, lung, heart, kidney, GI tract, gonads, brain, muscle, as well as in serum and transplanted tumor fragments was investigated by liquid scintillation counting. The peak levels in all organs with the exception of tumor and spleen were reached within 24 h. The highest levels were found in the organs of the reticuloendothelial system, liver, spleen, and lungs. The radioactivity in the other organs was found to be low, approximately 2%. In the tumor and the spleen the highest levels of radioactivity were found at approximately 7 d. At this stage the level of radioactivity in the tumor was 40 times higher than that in muscle. However, the amount of isotope detected in the tumor was still generally less than 1% of the injected dose. The concentration of radioactivity in the tumor was found to be quite variable. Higher levels of radioactivity were correlated with a low amount of tumor necrosis indicating the importance of viable tumor tissue for the accumulation of the radiolabel in this particular animal model.

Adult↗

PubMedDate not supplied

in vivo targeting of colloidal carriers by novel graft copolymers.

One of the major obstacles to the targeted delivery of colloidal carriers (nanocapsules) is the body's own defence mechanism in capturing foreign particles by the reticuloendothelial system (RES). This means that following intravenous administration, practically all nanometer size particles are captured by the RES (mainly the liver). This paper draws attention to a recent initiative on the design of 'macromolecular homing devices' which seem to disguise nanoparticles from the RES, and hence are of potential interest for the targeted delivery of nanocapsular carriers. The idea is based on a graft copolymer model embodying a link site for attachment (binding) to the carrier, a floating pad for maintaining the particles afloat in the blood stream, an affinity ligand for site-specific delivery and a structural tune for balancing the overall structure of the homing device. A general synthetic scheme for the preparation of such graft copolymers is given, and preliminary biological evaluations relating to the floating pad concept are discussed.

Animals↗

PubMedDate not supplied

Preparation of polymer nano- and microspheres by vinyl polymerization techniques.

The methodologies and techniques of producing polymer particles (nano- and microspheres) from vinyl monomers are described, with an emphasis on laboratory preparations. Five different techniques are employed in the preparation of polymer micro- and nanoparticles from vinyl monomers. Emulsion polymerization provides particles of about 50-200 nm in diameter, emulsifier free emulsion polymerization produces particles of about 100-1000 nm (0.1-1.0 micron), dispersion polymerization gives particles in the region of 0.3-10 micron, and suspension polymerization leads to the formation of particles of about 20 micron-2 mm. The gap in the 10-20 micron region may be filled by either seeded polymerization or by more elaborately performed suspension polymerization. All of the four techniques mentioned above produce regular, spherical particles. Precipitation polymerization, on the other hand, gives irregularly shaped particles in the range of 0.1-10 micron. An attempt is made to clarify the underlying differences between these techniques and to say how they are practised in the laboratory.

Emulsions↗

PubMedDate not supplied

Preparation of nano- and microspheres by polycondensation techniques.

Particle-forming polycondensation techniques can be divided into two main categories, namely normal polycondensation and interfacial polycondensation. Various normal polycondensation procedures employed for the preparation of nano- and microspheres are covered by this review, and are described under suspension polycondensation, dispersion polycondensation and precipitation polycondensation. Among these, suspension polycondensation procedures are generally applicable for the preparation of both nano- and microspheres. They are employed for the production of industrially important polycondensates such as phenolics, polyesters and polyurethanes, as well as for novel polymeric materials such as polycyclodextrins, mercury-binding polymercaptals, and polyurea microcapsules. Dispersion polycondensation leads to the formation of monodisperse nanoparticles, but it is not widely employed. Precipitation polycondensation produces non-spherical and polydisperse particles, and it is useful only if low molecular weights of the polymer and polydispersity of the particles do not adversely affect the intended application of the product.

Capsules↗

PubMedDate not supplied

Preparation of microspheres and microcapsules by interfacial polycondensation techniques.

A methodological review of the production of microspheres/microcapsules by interfacial polycondensation is presented and the mechanisms of particle and capsule formation are discussed. Procedures for interfacial polycondensation employed for the preparation of microspheres/microcapsules involve the polycondensation of two complementary monomers in a two phase suspension system. Each of the two complementary monomers resides largely in one of the two immiscible phases in the suspension system. The resulting polycondensate, which is formed at or on one side of the interface, may, or may not, be soluble in the droplet phase. If the polymer is soluble in the droplets, particulate microspheres or monolithic microcapsules are formed, i.e. particle forming interfacial polycondensation. If the polymer is insoluble in the droplets, it forms a membrane around them, and the droplets are thus individually encapsulated by the polymer. This leads to the formation of capsular microspheres or reservoir microcapsules, and hence capsule forming interfacial polycondensation. A major example of particle forming interfacial polycondensation is that of phosgene with bisphenol A recently developed for the production of polycarbonate resins in particle form. Capsule forming interfacial polycondensation is widely used to prepare polyamide (nylon) microcapsules containing proteins, pharmaceuticals, etc.

Capsules↗

PubMedDate not supplied

Naming microcapsules.

A system of nomenclature is proposed whereby microcapsules are named after their 'core', 'wall' or 'both core and wall', as may be desired. The proposed nomenclature provides short descriptive names, and eliminates the need for lengthy phrases often used in the microencapsulation literature.

Capsules↗

PubMedDate not supplied

Microcapsules for food.

A systematic description of various processes employed for microencapsulation of food additives is presented. Microencapsulation methods covered include spray drying, fluidized bed coating, extrusion, solvent extraction, coacervation, cocrystallization, liposome formation and molecular inclusion. Basic features of microcapsular products, such as morphology, particle size, core/coat characteristics, and release behaviour, are also highlighted.

Animals↗