Drug release characteristics of physically cross-linked thermosensitive poly(N-vinylcaprolactam) hydrogel particles.

The effect of physical cross-linking was studied on the formation and properties of thermosensitive polymer particles of poly(N-vinylcaprolactam), PVCL, and PVCL grafted with poly(ethylene oxide) macromonomer, PVCL-graft-C(11)EO(42). Loading and release of model drugs into/from the hydrogel particles were evaluated. Thermosensitive particles were stabilized by cross-linkers, the most feasible of which was salicylic acid (SA).

In vitro toxicity and permeation of cyclodextrins in Calu-3 cells.

Cyclodextrins (CDs) can improve the pulmonary drug delivery by increasing aqueous solubility, absorption and bioavailability of drugs. Although the systemic absorption of CDs from gastrointestinal tract is very limited, their systemic absorption after pulmonary administration cannot be excluded. The aims of this study were 1) to evaluate the in vitro toxicity of various CDs (alpha-, beta-, gamma-, hydroxypropyl-alpha-, hydroxypropyl-beta- and randomly methylated-beta-CD) in pulmonary Calu-3 cells and Calu-3 cell layers using MTT and LDH cytotoxicity tests, and 2) to study the permeation of natural CDs (alpha-, beta- and gamma-CD) at non-toxic concentrations across Calu-3 cell layers.

Failure of MTT as a toxicity testing agent for mesoporous silicon microparticles.

In this work, it is shown that the common toxicity indicator, MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide), will fail to predict the toxicity of porous silicon (PSi) microparticles. This is due to the spontaneous redox reactions where the MTT is reduced and the PSi particle surfaces are oxidized simultaneously. MTT was shown to even react with thermally oxidized and carbonized forms of PSi particles, although the treatment did give an enhanced protection against the unwanted reactions as compared to as-anodized PSi particles.

Cell-polymer interactions of fluorescent polystyrene latex particles coated with thermosensitive poly(N-isopropylacrylamide) and poly(N-vinylcaprolactam) or grafted with poly(ethylene oxide)-macromonomer.

Cell-polymer interactions of thermosensitive poly(N-isopropylacrylamide) (PNIPAM) or poly(N-vinylcaprolactam) (PVCL) coated particles with RAW264.7 macrophages and intestinal Caco-2 cells were evaluated. Nanosized particles were prepared by modifying the surface of fluorescent polystyrene (FPS) particles with the thermosensitive polymer gels or with poly(ethylene oxide) (PEO)-macromonomer grafts.

Cytotoxicity of thermosensitive polymers poly(N-isopropylacrylamide), poly(N-vinylcaprolactam) and amphiphilically modified poly(N-vinylcaprolactam).

Thermosensitive polymers poly(N-isopropylacrylamide) (PNIPAM), poly(N-vinylcaprolactam) (PVCL) and PVCL grafted with amphiphilic poly(ethylene oxide) (PEO) chains (PVCL-graft-C11EO42) were prepared and characterized and their putative cytotoxicity was evaluated. The cytotoxicity of these thermosensitive polymers and their monomers was investigated as a function of polymer concentration, incubation time and incubation temperature by using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) cytotoxicity tests in Caco-2 and Calu-3 cell cultures. Also, the influence of the chain end functionality on toxicity was examined.

Binding and release of drugs into and from thermosensitive poly(N-vinyl caprolactam) nanoparticles.

Three model drug substances, the beta-blocking agents nadolol and propranolol and a choline-esterase inhibitor tacrine, were used in order to determine how different drug molecules affect the behavior of thermally responsive polymer nanoparticles composed of poly(N-vinylcaprolactam) (PVCL). Pure PVCL particles in water exist in a swollen state at room temperature, but the size of the particles decreases discontinuously when the temperature is raised above the volume phase transition temperature. At temperatures above this transition temperature, water is expelled out from the nanoscopic hydrogel particles.