Microsphere

One concern with current techniques of UV reactor validation is that they provide only a measure of the mean UV fluence. In this research, the actual fluence distribution of a UV reactor is measured through the use of photochemically active fluorescent microspheres. ...

The two-part article aimed to investigate poloxamer 407-based microspheres as a novel platform for enhancing and controlling the delivery of atenolol across the oromucosal tissue. In the Part I of the work, atenolol-loaded poloxamers 407 microparticles were prepared by the solvent free spray congealing technology. This approach was feasible upon the high viscosity of the systems allowing for high loaded (20% w/w) non-aggregated microspheres. Several formulations were studied and the results demonstrated that the drug release patterns, solubility data, mucoadhesion to buccal tissue and gelling properties in saliva could be modified by adding different amount of an amphiphilic polymer-lipid excipient (Gelucire(®) 50/13) to poloxamer 407. Particularly, microspheres based only on poloxamer 407 exhibited very high solubility, mucoadhesive strength and gelling behaviour. To assess their potential as matrix for buccal application, the gelling property and the drug release from tablets obta...

The purpose of this work is to develop empirical equations for describing the in vitro ganciclovir (GCV) release from PLGA microspheres and also to develop and characterize a formulation containing GCV loaded PLGA microspheres dispersed in thermogelling PLGA-PEG-PLGA polymer gel. Effect of polymer chain length and polymer blending on GCV entrapment and release from PLGA microspheres is also examined. PLGA microspheres of GCV were prepared from two polymers PLGA 6535 (d,l-lactide:glycolideColon, two colons65:35, Mw=45,000-75,000 Da) and Resomer RG 502H (d,l-lactide:glycolideColon, two colons50:50, Mw=8000 Da) and a 3:1 mixture. PLGA-PEG-PLGA polymer was synthesized and characterized. In vitro GCV release studies were conducted with microspheres and microspheres dispersed in 23% w/v PLGA-PEG-PLGA solution. Polymer blended microspheres entrap more GCV (72.67+/-2.49%) than both PLGA 6535 (51.37+/-2.7%) and Resomer RG 502H (47.13+/-1.13%) microspheres. In vitro drug release data was fit ...

Microorganisms have been deliberately injected into groundwater environments for well over a hundred years. Reasons for the additions include increasing oil recovery from less permeable zones, increasing rates of organic contaminant biodegradation, a better understanding of the hydrologic properties of aquifers, particularly those characterized by a high degree of physical heterogeneity, a better understanding of the factors controlling the transport and (or) survival of pathogenic, genetically engineered, or other non-indigenous microorganisms in groundwater systems, and assessments of the vulnerability of an aquifer to microbial (pathogen) contamination. This chapter will focus on addition and recovery studies in which microorganisms are used as tracers in order to gain information about subsurface microbial transport behavior, biorestoration potential, geohydrology, or vulnerability to microbial contamination of groundwater systems. Because of the impor-tance of microbial-sized microspheres to the overall understanding of subsurface microbial attachment and transport behavior and of the hydrologic properties of different types of aquifers, the uses of microspheres as microbial-sized tracers are also discussed.

Biological drugs are usually complex proteins and cannot be orally delivered due to problems related to degradation in the acidic and protease-rich environment of the gastrointestinal (GI) tract. The high molecular weight of these drugs often results in poor absorption into the periphery when administered orally. The most common route of administration for these therapeutic proteins is injection. Most of these proteins have short serum half-lives and need to be administered frequently or in high doses to be effective. So, difficulties in the administration of protein-based drugs provides the motivation for developing drug delivery systems (DDSs) capable of maintaining therapeutic drug levels without side effects as well as traversing the deleterious mucosal environment. Employing a polymer as an entrapment matrix is a common feature among the different types of systems currently being pursued for protein delivery. Protein release from these matrices can occur through various mechanisms, such as diffusion through or erosion of the polymer matrix, and sometimes a combination of both. Encapsulation of proteins in liposomes has also been a widely investigated technology for protein delivery. All of these systems have merit and our worthy of pursuit. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:2497–2523, 2008

Polylactide homopolymers, polylactide and poly(ethylene oxide) diblock and triblock copolymers are used to prepare spherical microparticles by using the single oil-in-water emulsion and solvent evaporation technique. We are able to create both bulk and hollow microspheres by altering the conditions of preparation. The experiments are carried out at two fixed temperatures of 15 and 22 °C. We show, from scanning electron

The immune-stimulating activities of Bordetella bronchiseptica antigens containing dermonecrotoxin (BBD) loaded in chitosan microspheres (CMs) have already been reported in vitro and in vivo with a mouse alveolar macrophage cell line (RAW264.7) and mice. Therefore, this study attempted to demonstrate the successful induction of mucosal immune responses after the intranasal administration of BBD loaded in CMs (BBD-CMs) in colostrum-deprived pigs. The BBD was introduced to the CMs using an ionic gelation process involving tripolyphosphate (TPP). Colostrum-deprived pigs were then directly immunized through intranasal administration of the BBD-CMs. A challenge with a field isolate of B. bronchiseptica was performed ten days following the final immunization. The BBD-specific IgG and IgA titers, evident in the nasal wash and serum from the vaccinated pigs, increased with time (p<0.05). Following the challenge, the clinical signs of infection were about 6-fold lower in the vaccinated pi...

The two-part article aimed to investigate poloxamer 407-based microspheres as a novel platform for enhancing and controlling the delivery of atenolol across the oromucosal tissue. In the Part I of the work, atenolol-loaded poloxamers 407 microparticles were prepared by the solvent free spray congealing technology. This approach was feasible upon the high viscosity of the systems allowing for high loaded (20% w/w) non-aggregated microspheres. Several formulations were studied and the results demonstrated that the drug release patterns, solubility data, mucoadhesion to buccal tissue and gelling properties in saliva could be modified by adding different amount of an amphiphilic polymer-lipid excipient (Gelucire(®) 50/13) to poloxamer 407. Particularly, microspheres based only on poloxamer 407 exhibited very high solubility, mucoadhesive strength and gelling behaviour. To assess their potential as matrix for buccal application, the gelling property and the drug release from tablets obta...