Preparation and encapsulation techniques of chitosan microsphere for enhanced bioavailability of natural antioxidants.

Reactive oxygen species (ROS), induced by medical and life irradiation, have led to diverse diseases. Natural antioxidants (NAs) have been widely used to protect the body from the harmful effects of ROS. NAs have biocompatible properties but their bioavailability in the body is very low. This article discusses possible solutions to improve the bioavailability using several preparation and encapsulation techniques for microspheres using chitosan as a carrier. The first is the emulsion technique that controls particle size (0.5-1000 µm) according to the speed (RPM) of the agitator. The second technique discussed is spray drying-a very simple method that can control particle size (5-5000 µm) according to the nozzle size and discharge pressure. The third is the extrusion technique, which can control particle size (250-2500 µm) according to the syringe pore size. These techniques have enormous potential for use as drug delivery systems (DDS) in the functional food and biomedical field industries.

Triggered doxorubicin release using redox-sensitive hyaluronic acid-g-stearic acid micelles for targeted cancer therapy.

To develop a carrier for targeted drug delivery and triggered drug release in a reducing-tumor environment, reduction-sensitive hyaluronic acid-g-stearic acid (HCS) micelles were synthesized using a coupling agent. The HCS 40% was shown to have a more compact particle size than HCS 20% and the particle size of doxorubicin (DOX)-loaded HCS (HCSD) was increased relative to that of HCS micelles. The behavior of DOX release from HCSD showed that DOX was rapidly released in GSH (10 mM) solution. The site-specific targeting effect of HCSD nanoparticles was investigated by cellular uptake and competition assay at HCT116 and CT26 cell lines. An in vivo study of HCSD revealed that tumor suppression and site-specific targeted delivery of HCSD nanoparticles in HCT116-xenografted tumors were more superb than in the CT26-xenografted tumor. These results suggest that HCSD nanoparticles can be expected to have high therapeutic efficacy because they enable targeted drug delivery and rapid drug release.

Evaluation of hyaluronic acid-combined ternary complexes for serum-resistant and targeted gene delivery system.

Branched polyethylenimine (bPEI) was well known as high transfection agent, which has many amine group. However, utilization of bPEI was limited due to high toxicity. To solve these problems, bPEI was introduced to low molecular weight water-soluble chitosan (LMWSC) with coupling agent. In addition, hyaluronic acid (HA), one of natural anion polymer, was introduced to binary complex of pDNA/bPEI-grafted LMWSC (LMPEI) to target the specific cancer cell and impart the serum resistant. Ternary complexes of pDNA/LMPEI/HA were prepared by electrostatic charge interaction and their binding affinity and DNase protection assay were conducted by gel retardation assay. Particle size of ternary complexes showed that had each 482 ±â€¯245.4 (pDNA/LMPEI2%/HA, 1:16:1, w/w/w) and 410 ±â€¯78.5 nm (pDNA/LMPEI4%/HA, 1:16:2, w/w/w). Moreover, to demonstrate serum-resistant effect of ternary complexes, particle size of them was measured according to incubated time (0-10 h) under serum condition. Transfection assay of ternary complexes showed that their transfection efficiency in CD44-receptor overexpressed HCT116 cell was higher than CD44-receptor negative CT26 cell. Additionally, intracellular uptake of ternary complexes with propidium iodide (PI)-labeled pDNA was observed to confirm targeting effect and cellular internalization by fluorescence microscopy. These results suggest that ternary complexes are superb gene carrier with excellent serum-resistant and high gene transfection.

Evaluation of disulfide bond-conjugated LMWSC-g-bPEI as non-viral vector for low cytotoxicity and efficient gene delivery.

For efficient gene delivery, non-viral vectors should have high cellular uptake, excellent endosomal escape, and the ability to rapidly release the gene into the cytoplasm. Here, we developed a disulfide bond-conjugated bioreducible LMWSC-g-bPEI (LCP) composed of low molecular-weight water soluble chitosan (LMWSC), bPEI, and cystamine (Cys). The developed LCP had advantages such as low toxicity, great endosomal escape, and rapid release of pDNA into the cytoplasm. The polyplexes with LCP showed higher uptake into the nucleus and greater transfection efficiency than that without disulfide bond. Moreover, LCP polymer and polyplexes with LCP indicated lower cytotoxicity than bPEI 25kDa. In addition, a gel retardation assay and particle size were analyzed to demonstrate the reduction-sensitive gene delivery system. Besides, intracellular uptake pathway of polyplexes was investigated by various endocytosis inhibitor and confirmed to internalization into cell via macropinocytosis. These results suggest that bioreducible LCP is a superb non-viral vector for efficient gene delivery.

Simple nanophotosensitizer fabrication using water-soluble chitosan for photodynamic therapy in gastrointestinal cancer cells.

The polysaccharide chitosan has abundant cationic amine groups, and can form ion-complexes with anionic molecules such as the strong photosensitizer chlorin e6 (Ce6). In this study, water-soluble chitosan (WSC) was used to fabricate Ce6-incorporated nanophotosensitizers (Abbreviated as ChitoCe6 nanophotosensitizer) via a self-assembling process. This was accomplished by dissolving WSC in pure water and then directly mixing the solution with solid Ce6 causing ion complex formation between WSC and Ce6. The resulting nanophotosensitizer was spherical in shape and had a particle size of less than 300nm. The photodynamic effect of ChitoCe6 nanophotosensitizer was evaluated using gastrointestinal (GI) cancer cells. At in vitro study using SNU478 cholangiocarcinoma cells, ChitoCe6 nanophotosensitizer showed improved Ce6 uptake by tumor cells, reactive oxygen species production, and cellular phototoxicity. An in vivo study using SNU478-bearing nude mice showed that the ChitoCe6 nanophotosensitizer efficiently accumulated in the tumor tissue and inhibited tumor growth more than treatment with Ce6 alone. Furthermore, ChitoCe6 nanophotosensitizer was also efficiently absorbed through tissue layers in an ex vivo study using porcine bile duct explants. ChitoCe6 nanophotosensitizer showed enhanced photosensitivity and photodynamic effects against cancer cells in vitro and in vivo. We present ChitoCe6 nanophotosensitizer as a promising candidate for photodynamic therapy of GI cancer.

Anticancer effect of gene/peptide co-delivery system using transferrin-grafted LMWSC.

A series of ternary complex was designed to deliver psiRNA-bcl2 and (KLA)4 peptide into cancer cells for cancer therapy. The delivered psiRNA-bcl2 induced gene-silencing in a nucleus of cancer cells, while (KLA)4 peptide inhibited cancer growth via mitochondrial apoptosis, indicating that the ternary complexes exerted very strong synergistic effects on cancer growth suppression by acting on psiRNA-bcl2 and (KLA)4 peptide simultaneously. The ternary complexes having a targeting-ligand, transferrin (TfP), were found to be especially effective at binding to the TfP receptor rich cancer cells, HCT119. The plasmid DNA (pDNA) in ternary complexes was completely condensed at various content of LMWSC-PEG-TfP (32-64 times more than pDNA) and released into cells. pDNA in the complexes was protected from DNase present on the exterior of cells. The size (165-248 nm) of ternary complexes with LMWSC-PEG-TfP was increased, but surface charges (3-4.5 mV) were decreased. These results likely occurred because the free amine-group of LMWSC decreased in response to conjugated transferrin. Moreover, transfected ternary complexes with LMWSC-PEG-TfP were not expressed in the normal cells (HEK293), but were over expressed in HCT119 cells. These findings indicate that the ternary complexes can be specifically targeted to HCT119 cancer cells. The useful complexes for gene and peptide delivery had high anticancer activities via a synergistic effect due to co-operative action of psiRNA and (KLA)4 peptide in HCT119 cells.