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    发布时间:2013-10-30 20:48:41    点击:4144

研究生专题讲座


  目:Biomimetic approaches to surface functionalization for biomedical applications
 
报告人Prof. Marcus Twxtor
                 ETH Zurich, BioInterfaceGroup,
                 Department of Materials
                 Zurich, Switzerland
 
The number of potential applications of nanoparticles in biology and medicine, e.g., for application as contrast agents in medical imaging (diagnostics), for (targeted) drug delivery (therapy) and their combination (theragnostics) is rapidly increasing with emerging technologies to tune and control their bulk and, even more importantly, surface properties.
 
We have stabilized sub-30-nm iron oxide nanoparticles through catechol-derivative anchor groups, such as nitroDOPA, bound to poly(ethylene glycol) (PEG) and shown that the dispersed particles possess irreversible binding affinity to iron oxide and thus can optimally disperse superparamagnetic nanoparticles under physiologic conditions. This not only leads to ultrastable iron oxide nanoparticles but also allows close control over the hydrodynamic diameter and interfacial chemistry. Catechols in the form of DOPA are found in high concentrations in mussel adhesive proteins (MAPs) and contribute to the unique ability of MAPs to strongly bind to almost any material.
 
Further, we have prepared ultrasmall (<5 nm) iron oxide nanoparticles, and subsequently incorporated them into lipidic vesicles. Evidence from cryo-TEM provides evidence that nanoparticles are well dispersed in the hydrophobic core of the lipid membrane. Choosing a lipid system with a transition temperature above 40°C allowed for the design of a delivery system where hydrophilic model chemicals could be stably incorporated in the lumen of the liposomes at room temperature. Upon application of an ac magnetic field using an in vitro system, local heating of the membrane caused an increase of temperature to above the transition temperature and subsequent efficient release without destroying the liposomal structure and integrity.
 
In a second part, I will present results from culturing mammalian cells on 2D patterned surfaces and in microfabricated 3D wells, either hosting single cells or well defined cell clusters. Novel types of 3D culture substrates were produced in PDMS polymers and PEG hydrogels by efficient replication techniques from lithographically produced masters. Cells in 3D microenvironment were found to have very different adhesion, morphology and function. Finally, we have investigated the response of breast cancer cell clusters in 3D PEG hydrogel wells to the drug “Taxol*, demonstrating a platform that allows to interrogate separately factors affecting drug response, in particular dimensionality, cell-cell and cell-matrix interaction. Advanced 3D cell culture platforms have a great potential to reduce or eliminate in the future the need for animal testing.
 
  间:2013.11.1 (周五) 上午10:30
地 点:唐仲英楼B501室
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