Search

Poly(9-phenyl-2,4,8,10-tetraoxaspiro-[5,5]undcane-3-one) (PPTC) was synthesized by the microwave-assisted ring-opening polymerization (MROP) of a six-membered cyclic carbonate monomer 9-phenyl-2,4,8,10-tetraoxaspiro-[5,5]undcane-3-one (PTC) with tin(II) 2-ethylhexanoate (Sn(Oct)) or aluminum isopropoxide (Al(OPr)) as the catalysts. The obtained polycarbonates were further reduced by apalladium/carbonate catalyst (10% Pd/C) to afford partly deprotected polycarbonates containing hydroxyl groups (HPPTC). These two types of polycarbonates were characterized by H-NMR, Fourier transform infrared spectroscopy (FTIR), UV, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and automatic contact-angle measurements. The influence of the feed molar ratio of monomer-to-catalyst, the microwave irradiation power and the reaction time on the polymerization was also studied. The experimental results showed that HPPTC possessed significantly higher hydrophilicity and water absorption rate than PPTC. [ABSTRACT FROM AUTHOR]

Folate-containing dextran ligand (FA-Dextran-DTPA) was synthesized by the incorporation of diethylenetriaminepentaacetic acid (DTPA) and folate (FA) as a tumor-targeting group into dextran as a polymer carrier. This ligand was further reacted with gadolinium chloride to make a dextran gadolinium complex FA-Dextran-DTPA-Gd. The ligand and its gadolinium complex were characterized by H-NMR, FTIR, UV-Vis, average particle sizes and zeta potential, as well. In vitro properties including relaxivity, cytotoxicity assay, cellular uptake assay, and magnetic resonance imaging (MRI) were also evaluated. Compared with Gd-DTPA, FA-Dextran-DTPA-Gd possessed obviously higher relaxation effectiveness and lower cytotoxicity to HeLa cells. FA-Dextran-DTPA-Gd had a high affinity to the H460 and MDA-MB-231 tumor cells and can be taken up selectively by these tumor cells. Moreover, FA-Dextran-DTPA-Gd showed enhanced signal intensities (SI) of MRI and enhanced the contrast of MR images of tumor cells. These results indicated that FA-Dextran-DTPA-Gd showed the potential as a tumor-targeting contrast agent in MRI. [ABSTRACT FROM AUTHOR]

Polyetheretherketone (PEEK) is regarded as one of the most potential candidates of biomaterials in spinal implant applications. However, as a bioinert material, PEEK plays a limited role in osteoconduction and osseointegration. In this study, recombinant human bone morphogenetic protein-2 (rhBMP-2) was immobilized onto the surface of collagen-coated PEEK in order to prepare a multi-functional material. After adsorbed onto the PEEK surface by hydrophobic interaction, collagen was cross-linked with N-(3-dimethylaminopropyl)-N′-ethyl carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). EDC/NHS system also contributed to the immobilization of rhBMP-2. Water contact angle tests, XPS and SEM clearly demonstrated the surface changes. ELISA tests quantified the amount of rhBMP-2 immobilized and the release over a period of 30 d. In vitro evaluation proved that the osteogenesis differentiation rate was higher when cells were cultured on modified PEEK discs than on regular ones. In vivo tests were conducted and positive changes of major parameters were presented. This report demonstrates that the rhBMP-2 immobilized method for PEEK modification increase bioactivity in vitro and in vivo, suggesting its practicability in orthopedic and spinal clinical applications. [ABSTRACT FROM AUTHOR]

Polyetheretherketone (PEEK) is regarded as one of the most potential candidates for replacing current implant applications. To obtain good bone-implant interfaces, many modification methods have been developed to enable PEEK and PEEK-based composites from bio-inert to bioactive. Among them, physical methods have aroused significant attention and been widely used to modify PEEK for orthopedic implants. This review summarizes current physical modification techniques of PEEK for orthopedic applications, which include composite strategies, surface coating methods and irradiation treatments. The positive consequences of those modification methods will encourage continuing investigations and stimulate the wide range of applications of PEEK-based implants in orthopedics. [ABSTRACT FROM AUTHOR]

Purpose: The aim was to investigate anticancer drug-loaded poly(carbonate-ester) nanospheres as potential drug delivery systems for cancer therapy. Methods: Functional poly(carbonate-ester) copolymers (HPCP-SD) were synthesized by the incorporation of sulfadiazine as the tumor-targeting groups to hydroxyl groups of poly(carbonate-ester) copolymers. Two types of anticancer drug-loaded poly(carbonate-ester) nanospheres I and II were further prepared by dialysis method and high-voltage electrostatic field-assisted atomization, respectively, using HPCP-SD as polymeric carriers. These carriers and anticancer drug-loaded nanospheres were characterized, and their properties in vitro and in vivo were evaluated. Results: These anticancer drug-loaded poly(carbonate-ester) nanospheres had steady drug release rates and good controlled release properties. Moreover, anticancer drug-loaded poly(carbonate-ester) nanospheres II had faster drug release rates than those of anticancer drug-loaded nanospheres I. These anticancer drug-loaded nanospheres possessed lower cytotoxicity to HEK 293 cells and exhibited obviously higher anticancer efficiencies to the HeLa tumor cells than that of 5-fluorouracil. Anticancer drug-loaded nanospheres I possessed lower cytotoxicity to HEK 293 cells and higher anticancer activity to HeLa cells than those of anticancer drug-loaded nanospheres II. Conclusions: These anticancer drug-loaded poly(carbonate-ester) nanospheres showed the potential as drug delivery systems for cancer therapy. [ABSTRACT FROM AUTHOR]