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w 12 | Live from the Labs cnrs I international magazine Chemistry A new technique using nanoparticles to glue gels together holds exciting prospects for biomedical applications. Tiny Particles that Bind q Contact information: MMC, Paris. Ludwik Leibler > ludwik.leibler@espci.fr by Marianne Niosi A team led by CNRS researcher Ludwik Leibler1 has developed a simple adhesive for gels, known for being a “glue-adverse” material. Jelly-like, squishy, and wet, gels are extremely difficult to glue together. Made up of liquid trapped within a three-dimensional molecular network, they are highly useful in a variety of biomedical applications such as contact lenses, biological tissue growth, wound dressing, or drug delivery. The team spread a droplet of a commercially available aqueous solution of silica nanoparticles at the interface between two gels. After only 30 seconds of manual pressure, the two pieces of gel were solidly glued together. This quick adhesive process, which does not require any chemical reaction, relies on a phenomenon called adsorption. 2 The tiny silica particles create multiple weak bonds with the gel’s mesh-like molecular network, and soon become trapped in it. Leibler, who heads the MMC laboratory,3 was inspired by his previous research on vitrimers. Based on his understanding of the mechanism that allows this new material to change shape without breaking, he hypothesized that gels and nanoparticles could form very dynamic bonds that break and reform easily, allowing the adhesive joint to distort without breaking. The practical applications of this finding seem quite extensive. Although the researchers initially used simple gels such as poly(dimethylacrylamide) (PDMA) gels or gelatin, they showed that their solution could be applied to biological tissues, which have similar physical properties to those of gels. They successfully tested the technique on freshly-cut calf liver ribbons. More research is needed to fully grasp the mechanisms that drive adhesion and to fine-tune the properties of nanoparticle solutions. As for medical applications, there is still “a long way to go before finding optimal ways to put this discovery to use in the biological world,” concludes Leibler. 01. S. Rose et al., "Nanoparticle solutions as adhesives for gels and biological tissues," Nature, 2013. 505:382–5. 02. Adsorption is defined as an increase in the concentration of a dissolved substance at the interface of a solid, a liquid, or a gel, and a gas or liquid phase due to the operation of surface forces. 03. Matière molle et chimie (CNRS / ESPCI). Using the silica nanoparticle solution to glue two gels together. These three steps only take ten seconds. Paris A photo report can be viewed on the online version of the magazine: > www.cnrs.fr/cnrsmagazine © M. gracia /Laboratoire MMC-CNRS/ESPCI © C. FRESILLON/LOMA /CNRS Photot hèque


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