Metals controlled-release devices

Functionalized polymers are of interest in a variety of applications including but not limited to fire retardants, selective sorption resins, chromatography media, controlled release devices and phase transfer catalysts. This research has been conducted in an effort to functionalize a polymer with a variety of different reactive sites for use in membrane applications. These membranes are to be used for the specific separation and removal of metal ions of interest. A porous support was used to obtain membranes of a specified thickness with the desired mechanical stability. The monomer employed in this study was vinylbenzyl chloride, and it was lightly crosslinked with divinylbenzene in a photopolymerization. Specific ligands incorporated into the membrane film include dimethyl phosphonate esters, isopropyl phosphonate esters, phosphonic acid, and triethyl ammonium chloride groups. Most of the functionalization reactions were conducted with the solid membrane and liquid reactants, however, the vinylbenzyl chloride monomer was transformed to vinylbenzyl triethyl ammonium chloride prior to polymerization in some cases. The reaction conditions and analysis tools for uniformly derivatizing the crosslinked vinylbenzyl chloride / divinyl benzene films are presented in detail. 

Controlled-release devices that utihze the imique properties of conducting polymer membranes can also be configured. It has been shown that the transport properties of ICPs are dependent on the oxidation state of the membrane. This has been demonstrated both in solution (57) and for transport of volatiles (58). Extraordinary selectivity factors have been reported for the separation of some volatiles for example, selectivity factors of 3590 for H2/N2, 30 for O2/N2, and 336 for CO2/CH4 were reported (59). With membranes operational in solution, the controlled transport of simple ions (60), metal ions (61,62), small organic molecules (63), and even proteins (64,65) has been demonstrated. 

The scleral plug is a device that is implanted through a sclerotomy at the pars plana it releases the drug intravitreally (Fig. 4). Its shape is similar to that of a metallic scleral plug, which is used temporarily during pars plana vitrectomy. Controlled release of doxorubicin hydrochloride [adriamycin (ADR)] (15,16), GCV (3,4,17,19,21), fluconazole (18), 5-fluorouracil (20), and tacrolimus (FK506) (22) have been reported. 

Metal containing polymers are useful for a wide range of applications including analysis and catalysis, optical and electronic devices, colorants and coatings, structural composites, ceramics, controlled-released medicaments, and biocides. ... 

No current device meets all of these parameters. Diffusion-controlled release is demonstrated by transdermal patches e.g., birth-control, nicotine, etc.), whereas particulates such as metallic micro-/nanoparticles have been used to ablate cancer cells by localized heating with near-IR light.Whereas normal blood vessels have pore sizes <100 nm, the vessels adjacent to cancer cells have pore sizes between 100 and 200 nm. Hence, if DDS particulates e.g.y liposomes, polymeric micelles, metallic nanoparticles) are of this size regime, they will automatically situate nearby cancer cells. However, it usually takes at least 1 day of blood circulation to accumulate sufficient amounts. In order to hide the particles from the immune system, the particulates must be covered with a stealth lipsome such as poly (ethyleneglycol), PEG otherwise, the particulates will be filtered out of the body via the liver as urine. 

---