Key Engineering Materials
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Key Engineering Materials Vols. 342-343
Paper Title Page
Abstract: Thiolated polymers have been studied by many researchers because of the mucoadhesive
properties of thiol group. Alginate is a natural and biocompatible polymer that has been widely used
in drug delivery. In this study, thiolated chitosan microspheres (TCMs) were prepared by ionic
gelation process with tripolyphosphate and then, the bovine growth hormone (BGH) was loaded as
a model drug. Finally, the BGH-loaded TCMs (BTCMs) were coated with alginate to improve the
stability in gastrointestinal (GI) track. The alginate-coated BTCMs (ABTCMs) were observed as
spherical shapes. The average particle sizes of ABTCMs were 6.97±0.55 -m and the sizedistribution
was shown uniformly. Release of BGH from ABTCMs was decreased by coating with
alginate and increased rapidly with the change in medium pH from 1.2 to 7.4. Results indicate that
the ABTCMs have a potential as a drug carrier for oral drug delivery.
433
Abstract: The strategies developed for gene delivery are generally classified into two categories of
viral and non-viral vectors. The limitation of viral vectors, which have problems including toxicity,
immunogenicity and inflammatory response has led to the development of a novel, synthetic vectors
based on non-viral vectors. Chitosan, one of non-viral vectors, has been a good candidate in gene
delivery field. Moreover, galactosylated chitosan (GC) had the specific recognition of hepatocytes
by galactose in the GC. Also, carbonate apatite increased the rate of DNA endocytosis and the
efficiency of gene transfer. We describe here a new concept for improving cell specificity and
transfection efficiency by hybridization of carbonate apatite (CAp) with GC. The complex
formation was confirmed by agarose gel electrophoresis. The complex optimized through
controlling calcium ion and charge ratio was evaluated on the cell specificity and transfection
efficiency.
437
Abstract: The objective of this study is to investigate whether the PEGylated conjugated linoleic
acid (PCLA) as an anti-cancer prodrug can have favorable stability, biological activity, and
prevention of proliferation in MCF-7 breast cancer cells for anti-cancer when compared with
conjugated linoleic acid (CLA) itself. The CLA was simply coupled to poly(ethylene glycol) (PEG)
at melting state without solvent or catalyst through ester linkage between carboxylic group of CLA
and hydroxyl one of PEG. The results showed that the half life of PCLA was 55h in cell culture
medium at pH 7.4 and 37°C. Apoptosis of MCF-7 breast cancer cells were induced by not only
CLA- but PCLA-treatment with increasing concentrations whereas PCLA increased cell viability
when compared with CLA itself. These results indicate that the PCLA is a more stable and valuable
prodrug in that it has good stability and inhibition of cancer cell proliferation.
441
Abstract: The aim of this study is to prepare mucoadhesive chitosan microspheres for protein drug
to deliver to intestine through oral administration. The thiolated Eudragit was synthesized by
reaction between L-cysteine hydrochloride and Eudragit® L-100. About 8 mol-% of cysteine was
introduced to the Eudragit-cysteine conjugate. The conjugate was used to coat bovine serum
albumin (BSA)-loaded chitosan microspheres. The average particle sizes of BSA-loaded thiolated
Eudragit-coated chitsoan microspheres (TECMs) were 4.06±0.74 .m and the uniform sizedistribution
was shown. The in vitro release of BSA from BSA-loaded TECMs was pH-dependent.
Our results indicated that thiolated Eudragit might be a good candidate as a coating material for oral
delivery of protein drug owing to mucoadhesive and pH-sensitive properties.
445
Abstract: The key strategy for the advancement of gene therapy is the development of an efficient
targeted gene delivery system into cells. The targeted gene delivery system is especially important in
non-viral gene transfer which shows the relatively low transfection efficiency. It also opens the
possibility of selective delivery of therapeutic plasmids to specific tissues. Chitosan has been
considered to be a good candidate for gene delivery system, since it is already known as a
biocompatible, biodegradable, and low toxic material with high cationic potential. However, low
specificity and low transfection efficiency of chitosan need to be overcome prior to clinical trial. In
this study, we focused on the chemical modification of chitosan for enhancement of cell specificity
and transfection efficiency. Also, the potential of clinical application was investigated.
449
Abstract: Novel, biodegradable poly(ester amine)s (PEAs) were synthesized using hydrophobic
polycaprolactone diacrylate (PCLDA) and highly cationic polyethylenimine (PEI). This novel gene
carrier can form stable DNA complexes with particle sizes around 200 nm, and showing excellent
transfection efficiency and relatively low cytotoxicity compared with PEI 25K. Effect of
hydrophobicity on transfection efficiency and cytotoxicity was profound and was relatively
important parameter for the success of gene delivery.
453
Abstract: Polypropylenimine (PPI) dendrimers have been used by many researchers as gene
delivery carriers due to their high functionality. Glucose as a kind of carbohydrate is biocompatible
and hydrophilic. In this study, we synthesized glucosylated PPI (G-PPI) dendrimers to reduce
cytotoxicity. Glucose substitution of G-PPI dendrimers was determined by the sulfuric acid micromethod.
The G-PPI dendrimer was complexed with plasmid DNA in various N/P ratios, and the
complex was characterized. G-PPI dendrimers showed good DNA binding ability and high
protection of DNA from nuclease attack. The G-PPI dendrimer had low cytotoxicity compared to
PPI dendrimer by cytotoxicity assay. Also, transfection efficiency was influenced by glucosylation
degree and the transfection efficiency for the G-PPI-5 was slightly higher than that of PPI
dendrimer in HeLa cell line.
457
Abstract: Biodegradable in situ forming drug delivery systems that solidify or gel in the body from
injectable fluids represent effective parenteral depot systems for controlled delivery of proteins.
Various pharmaceutical additives were tested on their effectiveness as protein release modifiers and
stabilizers. Mono-, di-, poly-saccharides, PEG2K and salting-out salts except cyclodextrins
significantly decreased Tg of thermogelling polymers and their decreasing abilities were
proportional to the polymer concentration and additive/polymer weight ratio up to solubility limits
in aqueous media. For methyl cellulose (MC) gel, sodium carbonate, a strong salting-out salt,
decreased Tg by 23 °C so that in situ gel can be formed at the body temperature. The incorporation
of additives into thermogelling polymers significantly decreased the burst and retarded release
kinetics. Although the pH inside gel gradually dropped down due to the polymer degradation,
released model protein was confirmed to retain the original conformation.
461
Abstract: A naphthalocyanine dendrimer (DNPcZn) was synthesized as a potential
candidate of photosensitizer for photodynamic therapy. DNPcZn exhibited strong Q
band absorption around 780 nm, a useful wavelength for high tissue penetration. A
polyion complex (PIC) micelle (DNPcZn/m) system was formed via an electrostatic
interaction of anionic DNPcZn and poly(ethylene glycol)-poly(L-lysine) block
copolymers (PEG-b-PLL).
465
Abstract: In this study, we prepared using low molecular weight water-soluble chitosan nanoparticle loaded
paclitaxel (LMWSC-NPT) and investigated the potential as a drug carrier which is able to accumulate in the
tumor site. In the experiment of receptor-mediated endocytosis, LMWSC-NPT was treated with sodium azid
(NaN3) as an inhibitor of endocytosis process. As results, the antitumor activity of LMWSC-NPT treated
with sodium azid didn’t show but LMWSC-NPT was shown the high antitumor activity. Therefore,
LMWSC-NPs modified with hydrophobic group will be useful anticancer agent carrier via receptor-mediated
endocytosis.
469