Rob Deller one first prize for his poster at the SCRA Microscopy Conference, 21/09/12. His poster detailed his work on novel cryopreservation strategies based on modulating the growth of ice crystals.

Well done!

Our paper exploring the synthesis of degradable and responsive polymers by RAFT polymerization has been accepted in ACS Biomacromolecules. This paper builds on our previous report (Chem Comm 2012) on the synthesis of poly(disulfides) from RAFT derived macromonomers. In this report additional monomers are explored for their compatability with our methodology and their degradability is studied. In particular, it was shown that the polymers specifically degrade under conditions mimicing intracellular glutathione concentrations, and also can be tuned to undergo a shift in their responsive properties. This 'isothermal' transition will find use in intracellular delivery.

Read the paper here

Collaborative work with the Laboratory of Biomedical Imaging (EPFL, CH) is now availabe to read online.

Read the paper here

Abstract

We introduce photothermal optical lock-in Optical Coherence Microscopy (poli-OCM), a volumetric imaging technique, which combines the depth sectioning of OCM with the high sensitivity of photothermal microscopy while maintaining the fast acquisition speed inherent to OCM. We report on the detection of single 40 nm gold particles with a 0.5 µm lateral and 2 µm axial resolution over a 50 µm depth of field and the three-dimensional localization of gold colloids within living cells. In combination with intrinsic sample contrast measured with dark-field OCM, poli-OCM offers a versatile platform for functional cell imaging.

Collaborative work with the optics laboratory at EPFL on the direct visualisation of metallic nanoparticles inside living cells has been accepted for publication in Optics Express.

Read the paper here

The use of gold nanoparticles (AuNPs) for diagnostic applications and for drug and genedelivery is currently under intensive investigation. For such applications, biocompatibility and the absence of cytotoxicity of AuNPs is essential. Although generally considered as highly biocompatible, previous in vitro studies have shown that cytotoxicity of AuNPs in certain human epithelial cells was observed. In particular, the degree of purification of AuNPs (presence of sodium citrate residues on the particles) was shown to affect the proliferation and induce cytotoxicity in these cells. To expand these studies, we have examined if the effects are related to nanoparticle size (10, 11 nm, 25 nm), to the presence of sodium citrate on the particles' surface or they are due to a varying degree of internalization of the AuNPs. Since two cell types are present in the major barriers to the outside in the human body, we have also included endothelial cells from the vasculature and blood brain barrier.

Our paper describing how bioreduction of single polymer end groups can trigger an LCST type transistion has been accepted. Here we introduce hydrophilic or hydrophobic end groups via disulfide bond onto one end of a thermoresponsive polymer. Bioreduction of the end group by intracellular glutathione levels results in a solubility switch, normally associated with a temperature change (i.e. LCST). This work will allow us to alter the lipophilicity of drug carriers intracellularly along with delivery of bioactive compounds.

A collaborative manuscript (with REPAIR lab, Mainz) investigating the cytoxicity and uptake of gold nanoparticles into primary endothelial cells (major cell type in vasculature) is studied. This shows differences between immortalised and primary cell cultures as well contributions from residual citrate from their synthesis.

Lucienne won a prize for her post/flash presentaiton at the Syst. Bio. Annual Meeting. Well done!!