Microparticles and nanoparticles

Several methods have been demonstrated for the synthesis of microparticles and nanoparticles. The most popular among these is the solvent evaporation 

Water-soluble therapeutic proteins and peptides can be delivered using porous nanospheres or nanocapsules formed by a double emulsion solvent evaporation procedure. A concern with the delivery of proteins by nanoparticles is the loss of protein activity before its release. Desai et al. showed about 30% of tetanus toxoid activity was lost due after encapsulation and release from nanoparticles (Desai et al. 1996). Protein may be inactivated due to denaturation based on exposure to organic solvents and adsorption onto the oil-water interface during fabrication (van de Weert et al. 2000 Lu et al. 2000). A strategy for reducing adsorption of the therapeutic protein is the incorporation of human or bovine semm albumin in the aqueous phase, which restricts the access of the therapeutic protein to the phase interface (Kim and Park 1999). Another proposed cause of protein inactivation is decreased local pH experienced by the encapsulated protein due to acidic degradation byproducts. This can be addressed by including an alkaline buffer into the aqueous phase (Zhu et al. 2000). 

The half-Ufe of systemically injected particulate dmg delivery systems (including but not Umited to polymeric nanoparticles) within the circulation is 

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Microparticles and nanoparticles present some advantageous features, namely mucoadhesive properties. They have demonstrated some potential in vaginal drug delivery, particularly in the formulation of delivery systems for vaccines or peptides and proteins [160, 161], Nonetheless, these particles have to be incorporated in adequate carrier systems in order to be delivered. This task has been shown to be complex, it being hard to achieve controlled-release and steady-release profiles. 

Brannon-Peppas, L. Recent advances on the use of biodegradable microparticles and nanoparticles in controlled drug delivery. Int. J. Pharm. 1995, 116, 1-9. 

Antibodies have also been adsorbed or covalently linked to a variety of other carrier systems, such as liposomes (167,302), erythrocytes (303,304), and microparticles and nanoparticles, to selectively target them to a specific site in the body. In recent years, bispecific antibodies, which are designed to bind to two epitopes of either the same or different antigen (e.g., a cytotoxic drug and a cell receptor such as CD3), have also been used to target cytotoxic drugs, such as radionuclides, drugs, and toxins, to tumors. Interested readers are referred to several excellent reviews published recently (305,306). 

Solid-State Electrochemical Reactions of Electroactive Microparticles and Nanoparticles... 

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