Radio-frequency plasma polymerized biodegradable carrier for in vivo release of cis-platinum.

A low pressure plasma process based on plasma deposition has been used to develop a drug delivery strategy. In this study, a drug delivery system based on different layers of plasma co-polymerized Poly ε-caprolactone-Polyethylene glycol (PCL-PEG) co-polymers was deposited on biocompatible substrates. Cis-platinum (118 µgm/cm2) was used as an anti-cancer drug and incorporated for local delivery of the chemotherapeutic agent. The co-polymer layers and their interaction with cancer cells were analyzed by scanning electron microscopy. Our study showed that the plasma-PCL-PEG coated cellophane membranes, in which the drug, was included did not modify the flexibility and appearance of the membranes. This system was actively investigated as an alternative method of controlling localized delivery of drug in vivo. The loading of the anti-cancer drug was investigated by UV-VIS spectroscopy and its release from plasma deposited implants against BALB/c mice liver tissues were analyzed through histological examination and apoptosis by TUNEL assay. The histological examination of liver tissues revealed that when the plasma-modified membranes encapsulated the cis-platinum, the Glisson's capsule and liver parenchyma were damaged. In all cases, inflammatory tissues and fibrosis cells were observed in contact zones between the implant and the liver parenchyma. In conclusion, low pressure plasma deposited uniform nano-layers of the co-polymers can be used for controlled release of the drug in vivo.

The mechanical properties and in vitro biodegradation and biocompatibility of UV-treated poly(3-hydroxybutyrate-co-3-hydroxyhexanoate).

Strong mechanical properties and controllable biodegradability, together with biocompatibility, are the important requirement for the development of medical implant materials. In this study, an ultraviolet (UV) radiation method was developed to achieve controlled degradation for bacterial biopolyester poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) which has a low biodegradation rate that limits its application for many implant applications required quick degradation. When UV radiation was applied directly to PHBHHx powder, significant molecular weight (Mw) losses were observed with the powder, Mw reduction depended on the UV radiation time. At the same time, a broad PHBHHx Mw distribution was the result of inhomogeneous radiation. Interestingly, this inhomogeneous radiation helped maintain the mechanical properties of films made of the UV-radiated powder. In comparison, the PHBHHx films subjected to direct UV radiation became very brittle although their degradation was faster than that of the PHBHHx powders subjected to direct UV radiation. After 15 weeks of degradation in simulated body fluid (SBF), films prepared from 8 and 16h UV-treated PHBHHx powders maintained 92% and 87% of their original weights, respectively, while the untreated PHBHHx films lost only 1% of its weight. Significant increases in growth of fibroblast L929 were observed on films prepared from UV-radiated powders. This improved biocompatibility could be attributed to increasing hydrophilic functional groups generated by increasing polar groups C-O and CO. In general, UV-treated PHBHHx powder had a broad Mw distribution, which contributed to fast degradation due to dissolution of low Mw polymer fragments, and strong mechanical property due to high Mw polymer chains. Combined with its improved biocompatibility, PHBHHx is one more step close to become a biomedical implant material.

Encapsulation of osteoblast seeded microcarriers into injectable, photopolymerizable three-dimensional scaffolds based on d,l-lactide and epsilon-caprolactone.

UMR-106 seeded microcarriers were encapsulated into in situ, photopolymerizable three-dimensional scaffolds based on d,l-lactide and epsilon-caprolactone. UMR-106 and rat bone marrow cells proliferated and differentiated well on the microcarriers. The microcarriers were completely colonized after 14 days in culture. The viscous polymer paste allowed to mix the UMR-106 seeded microcarriers and gelatin (porosigen) properly. After the photopolymerization process, microcarriers and gelatin were evenly distributed throughout the scaffold. Gelatin was leached out within 7 h, and a porous scaffold was obtained. The microcarriers remained in the scaffold even after 7 days which demonstrates that they were well entrapped in the polymer. Increasing the amount of entrapped microcarriers (20-50%) leads to scaffolds with a reduced cross-linking. Hence, the microcarriers leached out. The encapsulated UMR-106 cells did not show pyknotic nuclei which demonstrates that the photopolymerization and handling the viscous polymer/gelatin/microcarrier paste is not detrimental for the cells.

Photoinduced phase separation and miscibility in the condensed phase of a mixed Langmuir monolayer.

We report our studies on the mixed Langmuir monolayer of mesogenic molecules, p-(ethoxy)-p-phenylazo phenyl hexanoate (EPPH) and octyl cyano biphenyl (8CB), employing the techniques of surface manometry and Brewster angle microscopy. Our studies show that the mixed monolayer exhibits higher collapse pressures for certain mole fractions of EPPH in 8CB as compared to individual monolayers. Also, a considerable reduction in the area per molecule is seen in the mixed monolayer, indicating a condensed phase. We have also studied the photostability of the mixed monolayer at different initial surface pressures. The mixed monolayer, under alternate cycles of UV and visible illumination, exhibits changes in surface pressures. This is due to the photoinduced transformation of EPPH isomers in the mixed monolayer. Our in-situ Brewster angle microscope studies for 0.5 mole fraction of EPPH in 8CB show a phase separation in the UV and a miscible phase in the visible, at low surface pressures ( approximately 5 mN/m). At higher surface pressures ( approximately 10 mN/m), under UV illumination, we find a phase separation which does not revert to a miscible phase under visible illumination.

Acid-initiated polymerization of epsilon-caprolactone under microwave irradiation and its application in the preparation of drug controlled release system.

Acid-initiated ring-opening polymerization (ROP) of epsilon-caprolactone (epsilon-CL) was conducted under microwave irradiation (MI) at 2.45 GHz. At this frequency, metallic catalysts were no longer necessary. The effects of microwave power, irradiation time, epsilon-CL: acid molar ratio and acidity of acid on the polymerization were investigated. Both the rate of polymerization and the molar mass of polymer obtained were enhanced in comparison with conventional thermal method. Poly(epsilon-caprolactone) (PCL) with weight-average molar mass (Mw) over 12000 g/mol and Mw/Mn below 1.6 was synthesized in the presence of carboxylic acids such as maleic acid (MA), succinic acid (SA) and adipic acid (AA). The polymerization was also carried out when the monomer contained a certain amount of ibuprofen (IBU), by which, the IBU-PCL controlled release system was prepared directly. The release of IBU from the system was sustained from 12 h to 9 days with IBU content in weight increasing from 5 to 20%. It seems that this is a promising method to prepare drug controlled release systems.