Source: Radboud University Nijmegen:
January 24, 2013
Chemists at Radboud University Nijmegen have created a gel made from helical polymers. The molecules twist together to form a ‘nano rope’, from which strong, stiff networks are produced. What is unusual is that a solution of the material is liquid when cold and turns into a gel when warmed – exactly the opposite of what happens to gelatine, for example. The leading scientific journal Nature published a paper showing how the ‘super gel’ works and its properties on 24 January. Together with the business community, the researchers are also developing various biomedical applications for this extraordinary gel.
Inspired by nature
The Nijmegen chemists Prof. Alan Rowan and Dr Paul Kouwer were inspired by the proteins that provide the cells in our bodies with their strength. Each cell contains thousands of these very thin but strong threads. They were able to mimic the winding structure of these proteins using a synthetic polymer – polyisocyanide (PIC). Kouwer: ‘We’ve made a copy that is almost exactly the same as the natural original, which is unprecedented. Not only is the structure of our material strikingly similar to the cell proteins, but the strength and sensitivity of the two materials are practically identical, even if you suddenly pull them hard.’ The structure provides the polymer with its unusual gel response – less than one gram of the solid substance needs to be added to a bucket of water to produce a strong gel. It therefore has a gel response one hundred times better than the commonly-used super gels (in nappies for example).
Stiffens when heated, melts in the refrigerator
What is also unusual about this substance is that it stiffens when the solution is warmed. The researchers show in Nature that the transition temperature of the solution can be varied between room temperature and body temperature, and the ability to adjust this temperature is very important in biomedical applications. The gel melts again when it is cooled.
Applications and patents
The structure of the gel implies huge opportunities for biomedical applications. Various options are being explored in partnership with Noviotech, a commercial partner of the Radboud University Nijmegen and Radboud University Nijmegen Medical Centre. Rowan: ‘One application is as a medium for the growth and manipulation of cells. Another potential application is in wound treatment. Once applied, the gel protects the wound: the microscopic structure allows fluid to pass through but keeps bacteria out. Once the wound has healed, the ‘plaster’ can be easily removed by cooling the gel.’ More and more possible applications for the super gel are emerging, with filters for nanomaterials and even cosmetic applications currently being investigated.
Fundamental and applied research
The paper published in Nature describes the fundamental properties of this unusual material. ‘When we first produced the material in the laboratory two years ago we knew that it was a very special substance, but did not yet understand why. The follow-up research has produced some fantastic results. And then I don’t mean just the publication of this paper, but also and especially the fact that the fundamental research has made the various applications much more feasible.’
See the Nature publication and click here.
NovioHelix® stands for a new thermoreversible gel product. One of its unique properties is the ability to form a well-defined nanoporous hydrogel (see below).
In the slides below we see the ‘cold’ gel (± 10 °C), on the left. It is almost 100% water and behaves like that. In the next slide (right) the gel is heated to 40 °C and forms a fully transparent gel. This phenomenon is fully reversible.
For a youtube demo of the NovioHelix gel, click here.
Properties of the NovioHelix gels:
- Fully synthetic
- Extremely high water content: 99.0 – 99.9% water. One teaspoon gelates 20 liters!
- Biocompatible and nontoxic;
- Nanoporous structures: porosity controllable between 100-250 nm;
- Thermal gelation: when aqueous solutions are heated, they gel at (tunable) temperatures.
- The gels are completely reversible: gels are formed upon heating yet will re-liquefy upon cooling;
- Stiffness tuneable between 10-1000 Pa.;
- Helical polymer provides a chemically achiral nanoenvironment;
- Optically transparent;
Customise your NovioHelix gels:
- Anchoring points available for standard (bio)conjugation;
- Introduction of multiple functional groups possible, for instance: fluorescent marker and a biomolecules (eg. with RGD peptides for cell growth);
- Tune the gelation temperature between 10 and 50 °C.
Future NovioHelix developments:
- Increase gel stability by (reversible) crosslinking reactions;
- Scaling-up of production
- GMP production
- Development of applications in bio and nano world.
Patent (pending): Method for the preparation of high molecular weight oligo(alkylene glycol) functionalized polyisocyanopeptides; WO 2011007012 A1