Polyethylenimine grafted-chitosan based Gambogic acid copolymers for targeting cancer cells overexpressing transferrin receptors.

Recent advancements in gene delivery systems that specifically target a variety of cancer types have increased demand for tissue-specific gene therapy. The current study describes the synthesis of a copolymer (GPgWSC) composed of a polyethylenimine (PEI)-grafted water-soluble chitosan (WSC) and gambogic acid (GA). It was validated as a ligand capable of enabling targeted attachment to transferrin receptors in HCT116 cancer cell lines. GPgWSC demonstrated superior antitumor activity in vitro in HCT116 compared to LoVo or MCF-7 cell lines, facilitated by the apoptotic activity of psiRNA-hBCL2. Pre-incubation of transferrin significantly inhibited GFP expression in the GPgWSC polyplex, demonstrating that GA is an extremely effective transferrin receptor targeting molecule. Additionally, in the HCT116-bearing mouse model, the tumor mass of PBS-treated mice increased to 2270 mm2 after 22 days, but the injection of GPgWSC polyplex significantly reduced the mass-increasing rate as a mass size of 248 mm2.

One-step synthesis of gene carrier via gamma irradiation and its application in tumor gene therapy.

INTRODUCTION: Although numerous studies have been conducted with the aim of developing drug-delivery systems, chemically synthesized gene carriers have shown limited applications in the biomedical fields due to several problems, such as low-grafting yields, undesirable reactions, difficulties in controlling the reactions, and high-cost production owing to multi-step manufacturing processes. MATERIALS AND METHODS: We developed a 1-step synthesis process to produce 2-aminoethyl methacrylate-grafted water-soluble chitosan (AEMA-g-WSC) as a gene carrier, using gamma irradiation for simultaneous synthesis and sterilization, but no catalysts or photoinitiators. We analyzed the AEMA graft site on WSC using 2-dimensional nuclear magnetic resonance spectroscopy (2D NMR; 1H and 13C NMR), and assayed gene transfection effects in vitro and in vivo. RESULTS: We revealed selective grafting of AEMA onto C6-OH groups of WSC. AEMA-g-WSC effectively condensed plasmid DNA to form polyplexes in the size range of 170 to 282 nm. AEMA-g-WSC polyplexes in combination with psi-hBCL2 (a vector expressing short hairpin RNA against BCL2 mRNA) inhibited tumor cell proliferation and tumor growth in vitro and in vivo, respectively, by inducing apoptosis. CONCLUSION: The simple grafting process mediated via gamma irradiation is a promising method for synthesizing gene carriers.

Targeting and synergistic action of an antifungal peptide in an antibiotic drug-delivery system.

Amphotericin B (AmB) has been widely used against fungal infections throughout almost the entire body, including the skin, nails, oral cavity, respiratory tract, and urinary tract. However, the development of AmB-loaded nanoparticles demands a novel technique that reduces its toxicity and other associated problems. Here, we developed a pH-responsive and redox-sensitive polymer-based AmB-delivery carrier system. In particular, this system was functionalized by conjugation with the antifungal peptide histatin 5, which acts both as a targeting ligand and a synergistic antifungal molecule against Candida albicans, a major systemic fungal pathogen of humans. Our results in vitro and in vivo suggest that this drug-delivery system may serve as a novel tool to facilitate the use of antimicrobial peptides as targeting ligands to pathogenic microbes, which would open new avenues of investigation in the field of drug delivery.

Effects of reduced chemical vapor deposition environment on growth and optical characteristics of TiO2 nanobelts.

TiO2-delta nanobelts were self-catalytically grown at 510 degrees C on bare Si (100) substrates using metallorganic chemical vapor deposition. The nanobelt formation was critically affected by the partial pressure of oxygen. The nanobelts were grown when supplying only Ar or a mixed gas of Ar (90%) and H2 (10%), while thin films were formed with an O2 gas flow of more than 50 cm3 min(-1). The nanobelts consisted of approximately 20-30 nm size rutile-dominant nanocrystallites. A vapor-solid growth mechanism excluding a liquid phase appeared to control the nanobelt formation. The grown TiO2-delta nanobelts showed a strong photoluminescence (PL) spectra peak at approximately 550 nm due to oxygen vacancies. The nanobelt surface possessed significant amount of oxygen vacancies contributing PL and actively reacting with the environment, indicating promise for photocatalytic and gas sensor applications in a visible light regime.