Ulrika Nilsson

Professor
Room: A329
Phone: +46 8 16 2327
ulrika.nilsson@aces.su.se

Staff Personal

I was employed as a researcher in Nov 1997, became docent in 2005 and professor 2014. I was formerly researcher at National Institute for Working Life (NIWL). During the first 10 years at SU, my focus was contaminants in work and indoor environments. We developed air-sampling techniques for isocyanates and organophosphate flame-retardants and plasticizers, and fast bioanalytical techniques, such as MIPs and membrane extraction techniques for the latter and their metabolites. A miniaturized denuder technique for personal exposure measurement was developed able to separate isocyanate vapor and aerosols. We also developed quantitative methods for airborne contaminants utilizing solid-phase microextraction (SPME).

My present research focus is analytical dermatochemistry, which involves skin allergens, their occurrence in commercial products and the environment, structure-activity relationships, and mechanisms behind hapten formation in the skin.

So far, eight Ph D students have been graduated under my supervision. Currently, my group consists of three Ph D students and a post doc.

Staff Research

Current research
Contact allergens: analytical methodology, exposure and study of hapten formation
This is a collaborative project involving colleagues at University of Gothenburg (GU), Prof Ann-Therese Karlberg, Doc Anna Börje and Dr Lina Hagvall. We have together identified a number of skin sensitizers, such as fragrance terpene hydroperoxides and epoxides in essential oils and ethyl isothiocyanate in neoprene rubber. A standard method has been developed for detection of strongly allergenic oxidized resin acids from colophonium in cosmetics and commercial products. A former Ph D student in my group (Sara Axelsson, now graduated) developed analytical methods for airborne oxidized resin acids in the wood pellets industry. Those compounds are known to cause both skin and airway problems among the workers.

Fragrance terpene hydroperoxides are among the most potent and common skin allergens and are formed when essential oils are handled and thus exposed to air. We have put lot of effort into the development of sensitive and quantitative methods for those compounds, and finally there is now a toolbox of methods at hand (Ph D student Ahmed Ramzy).

In order to start understanding the hapten formation between terpene hydroperoxides and skin proteins, we have studied some of them at their reactions with amino acids and model peptides. Specific adducts with amino acids moieties in the presence of an iron heme-like radical initiator were identified, which offer an explanation for the specificity of the immune response to structurally different hydroperoxides in animal experiments. In conclusion, we propose that immunogenic complexes of terpene hydroperoxides with skin proteins may be formed via a specific radical mechanism. We also found that the hydroperoxides only reacted in presence of radical initiator, suggesting that they may enter into the skin and remain inert until activated. This behavior may explain their strong sensitizing potencies.

Currently, we are studying the structure-reactivity-activity relationships for isothiocyanates, through their reactions with amino acids and peptides (Dr Isabella Karlsson). The activity (sensitizing potency) is reflected by LLNA and clinical patch test data.

Identification and quantification of a priori unknown protein adducts
This project is a joint collaboration with Doc Leopold Ilag and Prof Margareta Törnqvist. Measurement of protein adducts caused by exposure to reactive chemicals, such as electrophiles and many carcinogens, can be an important tool to assess health risks. Identification and quantification of a priori unknown protein adducts require highly sophisticated mass spectrometric methods. We are investigating novel scan techniques, sample preparation methods as well as tags for improved ionization efficiency (Ph D student Javier Zurita). The developed methods may be useful also for identifying the proteins involved in hapten formation at contact allergy.

Other research projects
In another project, led by Prof Caroline Leck, MISU, Arctic aerosols, fog and water are analyzed for surface active extracellular polysaccharides from marine microorganisms. Our contribution is to develop the highly sensitive and selective mass spectrometry methods needed for detection of the very low levels of biomolecules. One hypothesis is that sugars are transported into the atmosphere from the seawater surface microlayer and thereby contribute to the production of cloud condensation nuclei. We have now detected exopolysaccharides in seawater, pack ice and aerosols. Hopefully, this will provide more understanding of the Arctic aerosol-cloud system (Ph D student Farshid Mashayekhy Rad).

Staff Specialties

Mass spectrometry
Analytical method development for organic contact (skin) allergens

Analytical Chemistry

Analyzing organic chemicals: Basic research in method development and environmental / bioanalytical applications.