Nanospheres formulation

Cytotoxicity The cytotoxicity of nanocapsules was investigated against L929 mouse fibroblast cells and human polymorphonuclear PMNC cells with MTT assay [90], Cell viability values of different nanocapsule and nanosphere formulations on L929 and PMNC cells indicated that nonsurfactant P-CDC6 nanocapsules were less cytotoxic than nanocapsules containing surfactants. The cytotoxicity of the nanoparticles mostly arises from surfactant presence and was concentration dependent [90]. 

A.J. Ditto, P.N. Shah, L.R. Gump, YH. Yun, Nanospheres formulated from 1-tyrosine polyphosfliate exhibiting sustained release of polyplexes and in vitro controlled transfection properties. Mol. Hiarm. 6 (2009) 986-995. 

A.J. Ditto, P.N. Shah, S.T. Lopina, Y.H. Ytm, Nanospheres formulated from l-tyrosine polyphosphate as a potential intracellular delivery device, Int. J. Pharm. 368 (2009) 199-206. 

The procedure chosen for the preparation of lipid complexes of AmB was nanoprecipitation. This procedure has been developed in our laboratory for a number of years and can be applied to the formulation of a number of different colloidal systems liposomes, microemulsions, polymeric nanoparticles (nanospheres and nanocapsules), complexes, and pure drug particles (14-16). Briefly, the substances of interest are dissolved in a solvent A and this solution is poured into a nonsolvent B of the substance that is miscible with the solvent A. As the solvent diffuses, the dissolved material is stranded as small particles, typically 100 to 400 nm in diameter. The solvent is usually an alcohol, acetone, or tetrahydrofuran and the nonsolvent A is usually water or aqueous buffer, with or without a hydrophilic surfactant to improve colloid stability after formation. Solvent A can be removed by evaporation under vacuum, which can also be used to concentrate the suspension. The concentration of the substance of interest in the organic solvent and the proportions of the two solvents are the main parameters influencing the final size of the particles. For liposomes, this method is similar to the ethanol injection technique proposed by Batzii and Korn in 1973 (17), which is however limited to 40 mM of lipids in ethanol and 10% of ethanol in final aqueous suspension. 

Pfeifer, B. A., Burdick, J. A., and Langer, R. (2005),Formulation and surface modification of poly(ester-anhydride) micro- and nanospheres, Biomaterials, 26(2), 117-124. 

Chorny, M., Fishbein, I., Danenberg, H. D., and Golomb, G. (2002), Lipophilic drug loaded nanospheres prepared by nanoprecipitation Effect of formulation variables on size, drag recovery and release kinetics, J. Controlled Release, 83, 389-400. 

Intracellular infections were found to be a field of interest for drug delivery by means of nanospheres. Indeed, infected cells may constitute a reservoir for micro organisms, which are protected from antibiotics inside lysosomes. The resistance of intracellular infections to chemotherapy is often related to the low uptake of commonly used antibiotics or to their reduced activity at the acidic pH of lysosomes. To overcome these effects, the use of ampicillin, a p lactam antibiotic, bound to nanospheres was proposed as endocytozable formulation. The effectiveness of polyisohexylcyanoacrylate (PIHCA) nanospheres was tested in the treatment of two experimental intracellular infections. 

The properties of thermosetting and thermoplastic resin systems are continually improved to meet increasing performance requirements of end users. One way to enhance material properties is to incorporate nano-modifiers, based on elastomeric silicone particles, which are optionally grafted with other (acrylic) polymers to control dispersibility, viscosity, and other parameters. As an example, epoxy resin formulations have been modified with silicone nanospheres to improve low-stress behavior. Table 1 shows the outstanding fracture toughness improvement of silicone coreshell nanospheres, even at very low particle loading levels. 

Emulsions and suspensions are disperse systems that is, a liquid or solid phase is dispersed in an external liquid phase. While emulsions are sometimes formulated from oily drugs or nutrient oils their main function is to provide vehicles for drug delivery in which the drug is dissolved in the oil or water phase. Suspensions, on the other hand, are usually prepared from water-insoluble drugs for delivery orally or by injection, usually intramuscular injection. An increasing number of modern delivery systems are suspensions - of liposomes or of polymer or protein microspheres, nanospheres or dendrimers, hence the need to understand the formulation and stabilization of these systems. Pharmaceutical emulsions and suspensions are in the colloidal state, that is where the particles range from the nanometre size to visible (or coarse) dispersions of several micrometres. 

Surface active agents with bioadhesive microspheres or nanospheres have been discussed in the previous section. As these systems are suited to the appHcation on mucosal membranes, they are also used in peroral formulations. Furthermore, the formulation of proteins together with so-called carriers has been developed during the past few years. These carriers range from N-acylated a-amino acids [136] to aromatic amides and sulfamides [137] the mechanism of the latter system remains the subject of investigation. Carriers do... 

As summarized in Table 15.1, CyDs are often formulated as inclusion complexes to significantly increase encapsulation of lipophilic drugs within microspheres, nanospheres, and lipidic vesicles. 

Mukerjee A, Vishwanatha JK. Formulation, characterization and evaluation of curcumin-loaded PLGA nanospheres for cancer therapy. Anticancer Res. 2009 29(10) 3867-3875. 

Nanosuspensions consist of the pure poorly water-soluble drug without any matrix material suspended in dispersion. It is sub-micron colloidal dispersion of pure particles of drug stabilized by surfactants. By formulating nanosuspensions, problems associated with the delivery of poorly water-soluble drugs and poorly water-soluble and lipid-soluble drugs can be solved. Nanosuspensions differ from nanoparticles, " which are polymeric colloidal carriers of drugs (nanospheres and nanocapsules), and from solid-lipid nanoparticles, which are lipidic carriers of drug. 

For ophthalmic applications, properly formulated drug-loaded nanoparticles (DNPs) are reported to provide ease of application just like eye drop solutions, with the added advantage of being patient friendly, due to less frequent application and extended duration of retention in the extraocular portion. The drug may be attached to a nanoparticle matrix, or dissolved, encapsulated, and entrapped, giving rise to different terminologies as nanoparticles, nanospheres, or nanocapsules. " ... 

---