Zhi Yuan

Doxorubicin-loaded glycyrrhetinic acid-modified alginate nanoparticles for liver tumor chemotherapy.

Doxorubicin (DOX)-loaded glycyrrhetinic acid (GA)-modified alginate (ALG) nanoparticles (DOX/GA-ALG NPs) were prepared for targeting therapy of liver cancer. This study focused on the biodistribution of DOX/GA-ALG NPs in Kunming mice as well as their antitumor activity against liver tumors in situ and side effects. The biodistribution data showed that the concentration of DOX in the liver reached 67.8 ± 4.9 μg/g after intravenous administration of DOX/GA-ALG NPs, which was 2.8-fold and 4.7-fold higher compared to non-GA-modified nanoparticles (DOX/CHO-ALG NPs) and DOX·HCl, respectively. The concentration of DOX in the heart of mice treated with DOX/GA-ALG NPs at any sampling time was relatively lower than that of mice treated with DOX·HCl. The liver tumor growth inhibition rate (IR) in situ was about 52.6% and the mortality was 33% in DOX·HCl group. In contrast, the IR was 76.6% and no mice died in the DOX/GA-ALG NPs group. Histological examination showed tumor necrosis in both experimental groups. Most importantly, the heart cells and the liver cells surrounding the tumor were not affected by administration of DOX/GA-ALG NPs, whereas myocardial necrosis and apparent liver cell swelling were observed after DOX·HCl administration.

Glycyrrhetinic acid-modified chitosan/poly(ethylene glycol) nanoparticles for liver-targeted delivery

A liver-targeted drug delivery carrier, composed of chitosan/poly(ethylene glycol)-glycyrrhetinic acid (CTS/PEG-GA) nanoparticles, was prepared by an ionic gelation process, in which glycyrrhetinic acid (GA) acted as the targeting ligand. The formation and characterization of these nanoparticles were confirmed by FT-IR, dynamic light scattering (DLS) and zeta potential measurements. The biodistribution of the nanoparticles was assessed by single-photon emission computed tomography (SPECT), and the cellular uptake was evaluated using human hepatic carcinoma cells (QGY-7703 cells). The anti-neoplastic effect of the doxorubicin.HCl-loaded nanoparticles (DOX-loaded nanoparticles) was also investigated in vitro and in vivo. The results showed that the CTS/PEG-GA nanoparticles were remarkably targeted to the liver, and keep at a high level during the experiment. The accumulation in the liver was 51.3% at 3 h after injection; this was nearly 2.6 times that obtained with the CTS/PEG nanoparticles. The DOX-loaded nanoparticles were greatly cytotoxic to QGY-7703 cells, and the IC(50) (50% inhibitory concentration) for the free doxorubicin.HCl (DOX.HCl) and the DOX-loaded CTS/PEG-GA nanoparticles were 47 and 79 ng/mL, respectively. Moreover, the DOX-loaded CTS/PEG-GA nanoparticles could effectively inhibit tumor growth in H22 cell-bearing mice.

Glycyrrhetinic acid-modified poly(ethylene glycol)–b-poly(γ-benzyl l-glutamate) micelles for liver targeting therapy

Liver targeted micelles were successfully constructed via self-assembly of glycyrrhetinic acid (GA)-modified poly(ethylene glycol)-b-poly(gamma-benzyl l-glutamate) (GA-PEG-PBLG) block co-polymers, which were fabricated via ring opening polymerization of gamma-benzyl l-glutamate N-carboxyanhydride monomer initiated by GA-modified PEG. The in vivo biodistribution and the in vitro cellular uptake of these micelles were investigated. The results showed that the relative uptake of doxorubicin (DOX)-loaded micelles (DOX/GA-PEG-PBLG) in liver was much higher than in other tissues, and the resulting DOX concentration in liver was about 2.2-fold higher than that from the micelles without modification by GA. Moreover, the cellular uptake study demonstrated that the introduction of GA to the micelles could significantly increase the affinity for human hepatic carcinoma 7703 cells, which induced a 3.7-fold higher endocytosis than unmodified ones. The cytotoxicity of DOX/GA-PEG-PBLG micelles (IC(50) 47 ngml(-1)) was much higher than that of free DOX (IC(50) 90 ngml(-1)). These results indicate that GA-modified micelles have great potential in liver targeting therapy.

Self-assembly and liver targeting of sulfated chitosan nanoparticles functionalized with glycyrrhetinic acid.

A drug carrier based on glycyrrhetinic acid-modified sulfated chitosan (GA-SCTS) was synthesized. The glycyrrhetinic acid (GA) acted as both a hydrophobic group and a liver-targeting ligand. The GA-SCTS micelles displayed rapid and significant ability to target the liver in vivo. The IC(50) for doxorubicin (DOX)-loaded GA-SCTS micelles (DOX/SA-SCTS micelles) against HepG2 cells was 54.7 ng/mL, which was extremely lower than the amount of no-GA-modified DOX-loaded micelles. In addition, DOX/SA-SCTS micelles could target specifically the liver cancer cells. They had higher affinity for the liver cancer cells (HepG2 cells) than for the normal liver cells (Chang liver cells). There was nearly 2.18-fold improvement in uptake of the DOX/SA-SCTS micelles by HepG2 cells than that by Chang liver cells. These results indicate that GA-SCTS is not only an excellent carrier for drugs, but also a potential vehicle for liver-cancer targeting.

Functional alginate nanoparticles for efficient intracellular release of doxorubicin and hepatoma carcinoma cell targeting therapy.

In order to efficiently deliver chemotherapy drugs into hepatoma cells, a pH-sensitive and liver-targeted drug delivery system (glycyrrhetinic acid-modified alginate/doxorubicin-modified alginate complex nanoparticles), termed GA-ALG/DOX-ALG NPs, was prepared. First, GA-ALG and DOX-ALG were synthesized, and then GA-ALG/DOX-ALG NPs self-assembled by mixing GA-ALG and DOX-ALG via dialysis. Properties of pH-sensitivity, biodistribution in mice, and antitumor activity against ectopic hepatoma tumors in the NPs were evaluated. DOX release from GA-ALG/DOX-ALG NPs showed pH-sensitivity; less than 10% of drugs were liberated at pH 7.4 within 9 d while 58.7% of DOX released at pH 4.0. The confocal laser scanning microscope (CLSM) experiment showed that GA-ALG/DOX-ALG NPs can respond to the endosomal/lysosomal environment and had pH-triggered intracellular releasing property. The area under the curve (AUC(0-∞)) and half-life (t(½)) in the liver of GA-ALG/DOX-ALG NPs were 1156.7 μg h/g and 34.3 h, respectively, which was 11.8- and 3.2-fold higher than that of the DOX·HCl group. Furthermore, the inhibition rate of tumor growth was 79.3% after treatment with GA-ALG/DOX-ALG NPs, which was much higher than that of the DOX·HCl (48.5%) and DOX-ALG NPs groups (62.7%). Importantly, no mice died in the GA-ALG/DOX-ALG NPs group, while the mortality rate was 40% in the DOX·HCl group.

Silk Fibroin/Montmorillonite Nanocomposites: Effect of pH on the Conformational Transition and Clay Dispersion

By adjusting the solution pH value below the isoelectric point (pI) of silk fibroin (SF) protein, the SF was in the cation state and it could interact strongly with unmodified anionic montmorillonite (MMT) surface. In this way, novel SF-MMT nanocomposites with good clay dispersion were successfully obtained, which were confirmed by X-ray diffraction and transmission electron microscopy. Further 1H CRAMPS and 13C CP/MAS NMR experimental results revealed that beta-sheet content of SF was remarkably enhanced for nanocomposite prepared below the pI of SF (SF-MMTA) due to the strong interaction between MMT and SF. In SF-MMTA nanocomposite, clay layers acting as an efficient nucleator could efficiently enhance the beta-sheet crystallization. On the contrary, SF preserved the native random coil conformation in SF-MMTN nanocomposites due to the weak interaction between MMT and SF. A tentative model was suggested and used to explain the mechanism of clay dispersion and conformational transition of silk protein.

Role of thiol-containing polyethylene glycol (thiol-PEG) in the modification process of gold nanoparticles (AuNPs): Stabilizer or coagulant?

Gold nanoparticles (AuNPs) have significant potential as biosensors and drug delivery vehicles, as well as imaging and thermotherapy agents. Thiol-containing polyethylene glycol (PEG), hereafter denoted as thiol-PEG, is widely used as a macromolecular ligand for modifying AuNPs and stabilizing them under various environments. In this work, a series of thiol-PEG-modified AuNPs (PEGylated AuNPs) with different PEG molecular weights (Mw) were synthesized. The saturated capping density, charge-screening ability, and stability of the PEGylated AuNPs were then examined. The results showed that high-Mw PEG stabilized the AuNPs and screened the surface charge better than low-Mw PEG, but the latter showed higher saturated capping density. More importantly, PEG exhibited the maximum coagulation concentration (MCC) and critical stabilization concentration (CSC) in the stabilizing process of the AuNPs. Thiol-PEG acted as an AuNP stabilizer only when its concentration was higher than the CSC. Otherwise, thiol-PEG accelerated AuNPs aggregation, which reached the peak level at the MCC. These results were significant in recognizing the influence of thiol-PEG on the stability of AuNPs.

Insight into glycyrrhetinic acid: the role of the hydroxyl group on liver targeting.

Two kinds of glycyrrhetinic acid-modified chitosan/poly(ethylene glycol) nanoparticles (CTS/PEG-GA NPs) were prepared by an ionic gelation process in which the liver targeting ligand glycyrrhetinic acid (GA) was introduced into the nanoparticles at the C(30)-carboxyl group (CTS/PEG-GA(c) NPs) or the C(3)-hydroxyl group (CTS/PEG-GA(h) NPs). Their characteristics, especially their ability to target the liver, were compared. The results showed that both the CTS/PEG-GA(c) NPs and the CTS/PEG-GA(h) NPs are remarkably targeted to the liver. The accumulation in the liver is 51.3% and 56.5% of the injected dose for the CTS/PEG-GA(c)(4.60%) NPs (the subscript number denotes the GA content as weight percent in nanoparticles) and the CTS/PEG-GA(h)(4.57%) NPs at 3 h after injection, respectively. This is nearly 2.6-2.8 times higher than that obtained with the CTS/PEG NPs. According to our results, there is no significant difference between the CTS/PEG-GA(c) NPs and the CTS/PEG-GA(h) NPs in their ability to target the liver, when they were formed under identical conditions. This indicated that the C(3)-hydroxyl group in GA has little influence on the targeting ability.

Peptide REDV-modified polysaccharide hydrogel with endothelial cell selectivity for the promotion of angiogenesis.

Rapid and controlled vascularization of engineered tissues remains one of the key limitations in thick tissue engineering. Although many studies have focused on improving the rapid vascularization through the immobilization of bioactive molecules, the competition in growth between endothelial cells (ECs) and other cell types is to some extent neglected. In this study, we developed a peptide GREDV-modified scaffold for selective adhesion of human umbilical vein endothelial cells (HUVECs) through the specific recognition of the REDV peptide and integrin α4 β1 . In vitro studies showed that GREDV-conjugated alginate (ALG-GREDV) improved HUVEC adhesion, migration and proliferation when compared with a non-modified group. Furthermore, ALG-GREDV exhibited a superior capability for promoting the proliferation and selective adhesion of HUVEC over that of other peptide (RGD and YIGSR) modified groups (ALG-Pep). In vivo angiogenic assays demonstrated that the ALG-GREDV scaffold induced an angiogenic potential by stimulating new vessel formation and showed the highest blood vessel density among all samples after 21 days of implanting (83.7 vessels/mm(2) ). More importantly, the blood vessel density in cambium fibrous tissue of ALG-GREDV was about 1.5 times greater than other ALG-Pep groups, indicating facilitation of ALG-GREDV on selective angiogenesis in vivo. These results demonstrated that REDV-conjugated alginate could be a useful scaffold for stimulating and inducing angiogenesis in tissue-engineered applications.

Glycyrrhetinic acid-functionalized degradable micelles as liver-targeted drug carrier

Recently, many efforts have been devoted to investigating the application of functionalized micelles as targeted drug delivery carriers. In this study, glycyrrhetinic acid (GA, a liver targeting ligand) modified poly(ethylene glycol)-b-poly(γ-benzyl l-glutamate) micelles were prepared and evaluated as a potential liver-targeted drug carrier. The aggregation behavior, stability, size and morphology of the micelles were investigated. Anticancer drug doxorubicin (DOX) was encapsulated in the micelles. The drug release profile, in vivo distribution and the cytotoxicity against hepatic carcinoma QGY-7703 cells of DOX-loaded micelles were studied. The results indicated that the release profile was pH-dependent with Fickian diffusion kinetics. The micelles were remarkably targeted to the liver, inducing a 4.9-fold higher DOX concentration than that for free DOX·HCl. The DOX-loaded micelles exhibited almost twofold more potent cytotoxicity compared with DOX·HCl, and the cytotoxicity was time- and dosage-dependent. These results suggest that GA-functionalized micelles represent a promising carrier for drug delivery to the liver.