Amphiphilic Carboxymethyl Dextran Nanomicelles for Antibacterial Coating on Titanium

Peri-implantitis occurs at a significant rate, which is the leading cause of implant failure. The main reason for this unwanted complication is bacterial invasion and biofilm formation. To reduce the incidence of peri-implantitis, we constructed a carboxymethyl dextran (CMD) based nanomicelles antibacterial coating on microarc-oxidized titanium (MAO-Ti) surface. After cross-linking, the drug-loaded nanomicelles were spherical with a particle size of 130nm and uniformly dispersed. Zeta potential was negative, and the absolute value was greater than 10 mV, effectively avoiding micelles aggregation. It was observed by dynamic light scattering (DLS) that the stability of nanomicelles was significantly improved after cross-linking. The hemolysis rate of micelles was less than 5%, and the overall survival rate of human umbilical vein endothelial cells was more than 90%. After being coated on MAO-Ti surface, the cumulative drug release rate of drug-loaded nanomicelles reached 86.6% after 360 hours. Fluorescence staining of immobilized bacteria showed more dead bacteria on the coating surface, and the number of live bacteria was significantly reduced. It was concluded that dextran-based nanomicelles, which showed long-term drug release properties and excellent biocompatibility, are potential drug carriers for fabricating antibacterial coating on titanium surfaces.

Epoxy Functionalized Carboxymethyl Dextran Magnetic Nanoparticles for Immobilization of Alcohol Dehydrogenase

Microbial inhibition of carboxymethyl dextran (CMD) magnetic nanoparticles (MNPs) was investigated on two different bacterial cultures, Escherichia coli and Staphylococcus aureus, where inhibition properties of CMD-MNPs were confirmed, while uncoated MNPs exhibited no inhibition properties. To such CMD-MNPs, enzyme alcohol dehydrogenase (ADH) from Saccharomyces cerevisiae was immobilized. Later on, CMD-MNPs were functionalized, using an epoxide cross-linker epiclorohydrin (EClH) for another option of ADH immobilization. Residual activities of immobilized ADH onto epoxy functionalized and non-functionalized CMD-MNPs were determined. Effect of cross-linker concentration, temperature of immobilization and enzyme concentration on residual activities of immobilized ADH were determined, as well. With optimal process conditions (4% (v/v) EClH, 4 °C and 0.02 mg/mL of ADH), residual activity of immobilized ADH was 90%. Such immobilized ADH was characterized using FT-IR, SEM and DLS analysis.

Immobilization of alcohol dehydrogenase from Saccharomyces cerevisiae onto carboxymethyl dextran-coated magnetic nanoparticles: a novel route for biocatalyst improvement via epoxy activation

A novel method is described for the immobilization of alcohol dehydrogenase (ADH) from Saccharomyces cerevisiae onto carboxymethyl dextran (CMD) coated magnetic nanoparticles (CMD-MNPs) activated with epoxy groups, using epichlorohydrin (EClH). EClH was used as an activating agent to bind ADH molecules on the surface of CMD-MNPs. Optimal immobilization conditions (activating agent concentration, temperature, rotation speed, medium pH, immobilization time and enzyme concentration) were set to obtain the highest expressed activity of the immobilized enzyme. ADH that was immobilized onto epoxy-activated CMD-MNPs (ADH-CMD-MNPs) maintained 90% of the expressed activity. Thermal stability of ADH-CMD-MNPS after 24 h at 20 °C and 40 °C yielded 79% and 80% of initial activity, respectively, while soluble enzyme activity was only 19% at 20 °C and the enzyme was non-active at 40 °C. Expressed activity of ADH-CMD-MNPs after 21 days of storage at 4 °C was 75%. Kinetic parameters (KM, vmax) of soluble and immobilized ADH were determined, resulting in 125 mM and 1.2 µmol/min for soluble ADH, and in 73 mM and 4.7 µmol/min for immobilized ADH.

Magnetofluorescent Nanocomposite Comprised of Carboxymethyl Dextran Coated Superparamagnetic Iron Oxide Nanoparticles and β-Diketon Coordinated Europium Complexes

Red emitting europium (III) complexes Eu(TFAAN)3(P(Oct)3)3 (TFAAN = 2-(4,4,4-Trifluoroacetoacetyl)naphthalene, P(Oct)3 = trioctylphosphine) chelated on carboxymethyl dextran coated superparamagnetic iron oxide nanoparticles (CMD-SPIONs) was synthesized and the step wise synthetic process was reported. All the excitation spectra of distinctive photoluminesces were originated from f-f transition of EuIII with a strong red emission. The emission peaks are due to the hypersensitive transition 5D0→7F2 at 621 nm and 5D0→7F1 at 597 nm, 5D0→7F0 at 584 nm. No significant change in PL properties due to addition of CMD-SPIONs was observed. The cytotoxic effects of different concentrations and incubation times of Eu(TFAAN)3(P(Oct)3)3 chelated CMD-SPIONs were evaluated in HEK293T and HepG2 cells using the WST assay. The results imply that Eu(TFAAN)3(P(Oct)3)3 chelated CMD-SPIONs are not affecting the cell viability without altering the apoptosis and necrosis in the range of 10 to 240 μg/mL concentrations.