Hydrogel-based drug carriers have been developed from biocompatible materials, cyclodextrin, dextran and poly(ethylene glycol) and were used in zebrafish embryos. Maleimide modified dextrans (Dex... Show moreHydrogel-based drug carriers have been developed from biocompatible materials, cyclodextrin, dextran and poly(ethylene glycol) and were used in zebrafish embryos. Maleimide modified dextrans (Dex-mal) were functionalized with cyclodextrins and crosslinked to form a hydrogel using either per-6-thio-β-cyclodextrin (PSCD) or a combination of mono-6-thio-β-cyclodextrin (MSCD) and di-thiolated poly(ethylene glycol) (DSPEG). Using all-trans retinoic acid (RA) as a model hydrophobic drug, a sustained release from these cyclodextrin modified hydrogels was observed in vitro without an initial burst. This is because the cyclodextrin moiety in these hydrogels acts as a binding site for the RA. Furthermore, the nanosized hydrogel particles were injected into early stage zebrafish embryos in order to test in vivo release of RA and biocompatibility. We found the gel particles prepared from Dex-mal, MSCD and DSPEG were suitable for use in zebrafish embryos and it showed the release of RA in the embryos occurs in a controlled manner. Show less
Live-cell imaging techniques are essential to gain a better understanding of microbial functioning in natural systems, for example in biofilms. Autofluorescent proteins, such as the green... Show moreLive-cell imaging techniques are essential to gain a better understanding of microbial functioning in natural systems, for example in biofilms. Autofluorescent proteins, such as the green fluorescent protein (GFP) and the red fluorescent protein (DsRed), are valuable tools for studying microbial communities in their natural environment. Because of the functional limitations of DsRed such as slow maturation and low photostability, new and improved variants were created such as mCherry. In this study, we developed genetic tools for labeling Gram-negative bacteria in order to visualize them in vitro and in their natural environment without the necessity of antibiotic pressure for maintenance. mcherry was cloned into two broad host-range cloning vectors and a pBK-miniTn7 transposon under the constitutive expression of the tac promoter. The applicability of the different constructs was shown in Escherichia coli, various Pseudomonas spp. and Edwardsiella tarda. The expression of mcherry was qualitatively analyzed by fluorescence microscopy and quantified by fluorometry. The suitability of the constructs for visualizing microbial communities was shown for biofilms formed on glass and tomato roots. In addition, it is shown that mCherry in combination with GFP is a suitable marker for studying mixed microbial communities. Show less
Akker, W.M. van den; Durston, A.J.; Spaink, H.P. 2010
