Synthesis, characterization and potential applications for oxidized agarose.

The knowledge of agarose (AG) oxidation using periodate as oxidizer has not been systematically explored. This paper synthesized oxidized agarose (OAG) using solid-sate and solution reaction methods; the reaction mechanism and the properties of OAG samples were systematically evaluated. Chemical structure analysis disclosed that the aldehyde group and carboxyl group contents in all OAG samples are extremely low. Meanwhile, crystallinity, dynamic viscosity and molecular weight of OAG samples is lower than that of the original AG. Reaction temperature, time and sodium periodate dosage are inversely proportional to the decline of the gelling temperature (Tg) and melting temperature (Tm); and the Tg and Tm for the OAG sample obtained are even 19 °C and 22 °C lower than that of the original AG. The as-synthesized OAG samples all possess excellent cytocompatibility and blood compatibility; and can promote the proliferation and migration of fibroblast cells. Last but not least, the gel strength, hardness, cohesiveness, springiness and chewiness of the OAG gel can be effectively regulated via oxidation reaction. In conclusions, both solid and solution oxidation can regulate the physical properties of OAG and enlarge its potential applications in wound dressing, tissue engineering and food areas.

Synthesis of Gentamicin-Immobilized Agar with Improved Antibacterial Activity.

To develop agar derivatives with good antibacterial activity and decreased gelling and melting temperatures, two agar-gentamycin conjugates with 9.20% and 12.68% gentamicin immobilized were fabricated by oxidation, Schiff base and reduction reaction, and characterized by a Fourier Transform Infrared Spectrometer, 1H nuclear magnetic resonance and an elemental analyzer. It was found that the modifications changed the intermolecular interactions, leading to decreased gelling and melting temperatures for the oxidized agar and slightly increased gelling and melting temperatures for agar-gentamycin conjugates. Further studies of antimicrobial properties showed that the two agar-gentamycin conjugates possessed good antibacterial activity, which was positively correlated with the dosage and the immobilization rate of gentamicin. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of agar-gentamycin conjugates with higher immobilization rates of gentamicin against Escherichia coli were 39.1 µg/mL and 156.2 µg/mL, respectively, and the MICs and MBCs against Staphylococcus aureus were 19.5 µg/mL and 78.1 µg/mL, respectively. A biofilm test indicated that certain concentrations of agar-gentamycin conjugate could effectively inhibit the biofilm formation of Escherichia coli and Staphylococcus aureus. In summary, agar-gentamycin conjugates possess good antibacterial activities and may be applied as a new kind of antibacterial material.