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Lourdes Basababe Desmonds (promorion date: 13 January 2006)

Fluorescent Self-Assembled Monolayers as New Sensing Materials

Promotion Date: 13 January 2006

Lourdes Basababe Desmonds

First we have developed a new fluorescent material for chemical sensing. The idea is to detect chemical substances with the fluorescent properties of the material. This material consists on glass slides coated with a mix monolayer of fluorescent and receptor molecules for metal ions and inorganic anions.
Thanks to the receptors molecules the material is able to complex the analytes, if that happen the fluorescence of the material changes and therefore we are able to detect the presence of the analyte.
After that, we have integrated this sensing material into microfluidic channels to generate sensing chips.
And finally we have applied these sensing materials in nanotechnology, generating fluorescent and metal ion micropatterns in glass surfaces. We wanted to develop a general method, not one single sensor for one analyte.

What was your thesis about?

First we have developed a new fluorescent material for chemical sensing. The idea is to detect chemical substances with the fluorescent properties of the material. This material consists on glass slides coated with a mix monolayer of fluorescent and receptor molecules for metal ions and inorganic anions. Thanks to the receptors molecules, the material is able to complex the analytes. If that happens, the fluorescence of the material changes and therefore we are able to detect the presence of the analyte. After that, we have integrated this sensing material into microfluidic channels to generate sensing chips. And finally we have applied these sensing materials in nanotechnology, generating fluorescent and metal ion micropatterns in glass surfaces. We wanted to develop a general method, not one single sensor for one analyte.
The fabrication of our fluorescent sensing surfaces is simpler than the fabrication of many other fluorescent chemosensors. Their easy synthesis allows the generation and screening of libraries of surfaces with different properties. These libraries can be used to identify the best sensor for a certain analyte, or they may be used all together to generate a fingerprint type of response towards the presence of the analyte, this is called differential sensing.

But how do you develop a number of sensors?

Making different combinations of fluorophores and receptor molecules at the surface, you can generate a number of different sensing surfaces with different properties. This allows obtaining easily a collection of sensors. When these sensors are not very specific, the collective response of the entire group may be used for the recognition of the analytes. Like our nose, or our tongue where numerous sensors work together to, for instance, distinguish the smell of coffee, or the taste of suit. Therefore large arrays of unspecific chemical sensors used for the recognition of analytes or mixtures of analytes, are called ‘electronic noses or tongues’. The sensing surfaces that we have developed can be applied to the fabrication of new electronic tongues.

So it was a success?

Yes it was a big success, we demonstrated this new concept for the fabrication of fluorescent sensing materials. As well we demonstrated the versatility and generality of the sensing scheme applying these surfaces for the detection of a number of cationic and anionic species. Looking towards application, we were able to integrate it into microfluidic chips, and we were able to use it for the generation and visualization of micro-patterns of metal ions in glass surfaces. These new materials may have important implications in the development of chemosensors and in nanotechnology. Part of the work has been already published and I am currently writing some more publications about it.

Is your ‘artificial tongue’ the first?

No, differential sensing is not a new concept. And also we have not developed a new artificial tongue, we have just fabricate a new material that may be used for that. Although this has been the first time that a fluorescent chemosensor array has been integrated in microfluidics chips, what will open the way to differential sensing in microdivices.

You are from Spain, how did you come to do a PhD here?

I got a fellowship from my University in Spain. I came to the group of David Reinhoudt for four months and I did some organic synthesis. Then I got the offer for a PhD position. Being back in Spain I soon realized that the conditions in the Netherlands are better, so I came.
The facilities you have here for your research are not limited money wise. Here money is invested in ideas that may or may not work, which is very good for science. Also I find all the facilities you have to collaborate with other groups extremely good, which gives you the chance to do a multidisciplinary research. It has been a great experience, professionally and personally. I have specially enjoyed the international environment in my group.

What didn’t you enjoy?

Well, it takes a while to adapt. To the university system for instance, which is far more self-learning than in Spain. On the whole I am enthusiastic about my time here. I did not have the uncertainty whether I would finish or not my PhD, although it was an enormous lot of work and sometimes very stressful.

What are your plans?

I want to go back to Spain eventually, maybe not just now, but I do not see my whole life in a foreign country. The next 1st of May I will start in a Post doctoral position in the Biomedical Diagnostics Institute at the Dublin City University (Ireland).

For the summary of the thesis, click here. (English)