Metallated porphyrin-doped conjugated polymer nanoparticles for efficient photodynamic therapy of brain and colorectal tumor cells.

AIM: Assess biocompatibility, uptake and photodynamic therapy (PDT) mechanism of metallated porphyrin doped conjugated polymer nanoparticles (CPNs) in human brain and colorectal tumor cells and macrophages. MATERIALS & METHODS: CPNs were developed employing 9,9-dioctylfluorene-alt-benzothiadiazole, an amphiphilic polymer (PS-PEG-COOH),  and platinum octaethylporphyrin. T98G, SW480 and RAW 264.7 cell lines were exposed to CPNs to assess uptake and intracellular localization. Additionally, a PDT protocol using CPNs was employed for the in vitro killing of cancer and macrophage cell lines. RESULTS & CONCLUSION: CPNs were well incorporated into glioblastoma and macrophage cells with localization in lysosomes. SW480 cells were less efficient incorporating CPNs with localization in the plasma membrane. In all cell lines PDT treatment was efficient inducing oxidative stress that triggered apoptosis.

Polymer films with surfaces unmodified and modified by non-thermal plasma as new substrates for cell adhesion.

The surface properties of biomaterials, such as wettability, polar group distribution, and topography, play important roles in the behavior of cell adhesion and proliferation. Gaseous plasma discharges are among the most common means to modify the surface of a polymer without affecting its properties. Herein, we describe the surface modification of poly(styrene) (PS) and poly(methyl methacrylate) (PMMA) films using atmospheric pressure plasma processing through exposure to a dielectric barrier discharge (DBD). After treatment the film surface showed significant changes from hydrophobic to hydrophilic as the water contact angle decreasing from 95° to 37°. All plasma-treated films developed more hydrophilic surfaces compared to untreated films, although the reasons for the change in the surface properties of PS and PMMA differed, that is, the PS showed chemical changes and in the case of PMMA they were topographical. Excellent adhesion and cell proliferation were observed in all films. In vitro studies employing flow cytometry showed that the proliferation of L929 cells was higher in the film formed by a 1:1 mixture of PS/PMMA, which is consistent with the results of a previous study. These findings suggest better adhesion of L929 onto the 1:1 PS/PMMA modified film, indicating that this system is a new candidate biomaterial for tissue engineering.

Effect of calcium ions on rat osseous plate alkaline phosphatase activity.

Rat osseous plate alkaline phosphatase is a metalloenzyme with two binding sites for Zn2+ (sites I and III) and one for Mg2+ (site II). This enzyme is stimulated synergistically by Zn2+ and Mg2+ (Ciancaglini et al., 1992) and also by Mn2+ (Leone et al., 1995) and Co2+ (Ciancaglini et al., 1995). This study was aimed to investigate the modulation of enzyme activity by Ca2+. In the absence of Zn2+ and Mg2+, Ca2+ had no effects on the activity of Chelex-treated, Polidocanol-solubilized enzyme. However, in the presence of 10 microM MgCl2, increasing concentration of Ca2+ were inhibitory, suggesting the displacement of Mg2+ from the magnesium-reconstituted enzyme. For calcium-reconstituted enzyme, Zn2+ concentrations up to 0.1 microM were stimulatory, increasing specific activity from 130 U/mg to about 240 U/mg with a K0.5 = 8.5 nM. Above 0.1 microM Zn2+ exerted a strong inhibitory effect and concentrations of Ca2+ up to 1 mM were not enough to counteract this inhibition, indicating that Ca2+ was easily displaced by Zn2+. At fixed concentrations of Ca2+, increasing concentrations of Mg2+ increased the enzyme specific activity from 472 U/mg to about 547 U/mg, but K0.5 values were significantly affected (from 4.4 microM to 38.0 microM). The synergistic effects observed for the activity of Ca2+ plus magnesium-reconstituted enzyme, suggested that these two ions bind to the different sites. A model to explain the effect of Ca2+ on the activity of the enzyme is presented.

Mechanism of action of cobalt ions on rat osseous plate alkaline phosphatase.

Polidocanol-solubilized osseous plate alkaline phosphatase was modulated by cobalt ions in a similar way as by magnesium ions. For concentrations up to 1 microM, the Chelex-treated enzyme was stimulated by cobalt ions, showing Kd = 6.0 microM, V = 977.5 U/mg, and site-site interactions (n = 2.5). Cobalt-enzyme was highly unstable at 37 degrees C, following a biphasic inactivation process with inactivation constants of about 0.0625 and 0.0015 min-1. Cobalt ions stimulated the enzyme synergistically in the presence of magnesium ions (Kd = 5.0 microM; V = 883.0 U/mg) or in the presence of zinc ions (Kd = 75.0 microM; V = 1102 U/mg). A steady-state kinetic model for the modulation of enzyme activity by cobalt ions is proposed.