Preparation of oxidized sodium alginate with different molecular weights and its application for crosslinking collagen fiber

A series of periodate oxidized sodium alginate (OSA) were prepared as green polysaccharide-based crosslinkers. The molecular weight of OSA decreased, while their aldehyde group content increased with increasing dosage of sodium periodate. A typical OSA was further fractionated to four fractions by ethanol with a narrower molecular weight distribution. Then the crosslinking performances of OSAs/fractions on collagen fiber (CF) were investigated. DSC and SEM analyses showed that the thermal stability and dispersion degree of crosslinked CF was considerably enhanced with decreasing molecular weight of OSA. The effect of aldehyde group content of OSA on its crosslinking performance was less obvious than that of molecular weight, probably because the aldehyde group content in each OSA sample was higher than the amino group content of CF involved in the crosslinking reaction. In general, molecular weight of OSA plays a decisive role in improving properties of the crosslinked CF.

Adsorption of uranium by amidoximated chitosan-grafted polyacrylonitrile, using response surface methodology

The amidoximated chitosan-grafted polyacrylonitrile (CTS-g-PAO) was prepared for the adsorption of uranium from water. The effects of pH, concentration of uranium and the solid-liquid ratio on the adsorption of uranium by CTS-g-PAO were optimized using Doehlert design of response surface methodology (RSM). The adsorption capacity and removal efficiency achieved 312.06 mg/g and 86.02%, respectively. The adsorption process attained equilibrium only in 120 min. More than 80% of the absorbed uranium could be desorbed by 0.1 mol/l HCl or EDTA-Na, and CTS-g-PAO could be reused at least 3 times. The CTS-g-PAO and U(VI) ions formed a chelate complex due to FTIR spectral analysis. The surface morphology of CTS-g-PAO was also investigated by SEM. The adsorption process was better described by Langmuir isotherm and pseudo second order kinetic model. Results obtained indicated that CTS-g-PAO was very promising in adsorption of uranium from water.

Improvement of pharmacokinetic and antitumor activity of PEGylated liposomal doxorubicin by targeting with N-methylated cyclic RGD peptide in mice bearing C-26 colon carcinomas

Cyclic Arg-Gly-Asp (cRGD) pentapeptides engrafted liposomes have attracted considerable attention for targeting integrin receptors on tumor vasculature. In this study PEGylated liposomal doxorubicin (PLD) was decorated with three cRGD peptides including Arg-Gly-Asp-D-Tyr-Cys (RGDyC), Arg-Gly-Asp-D-Phe-Lys (RGDfK) and Arg-Gly-Asp-D-Phe-[N-Methyl]Lys (RGDf[N-Met]K). The in vitro liposome-cell-association and cytotoxicity experiments demonstrated the RGD-PLDs capability of internalization into integrin expressing HUVEC cells via receptor mediated endocytosis. The biodistribution studies revealed that decreasing the hydrophilicity of the peptide greatly reduces the RGD-PLDs blood clearance rate and increases their localization in C-26 colon carcinoma tumor model. Meanwhile, the most selective version, RGDf[N-Met]K, which has intermediate hydrophilicity revealed the lowest unwanted interactions with other integrin presenting sites, further localization in tumor, and lower doxorubicin (Dox) side effects. RGDf[N-Met]K-PLD demonstrated a superior control of tumor growth and increased the survival of mice. In this study, we introduced RGDf[N-Met]K for the first time, as a promising ligand for active targeting of liposomes to solid tumor which merits further investigations.