Leopold Ilag

Leopold Luna Ilag


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Works at Department of Materials and Environmental Chemistry
Telephone 08-16 24 35
Visiting address Svante Arrhenius väg 16 C
Room A 313
Postal address Institutionen för material- och miljökemi 106 91 Stockholm

About me

Leopold is originally from the Philippines but has been living in Europe since starting graduate studies in 1992. He obtained his PhD (1997)  from the Department of Medical Biochemistry and Biophysics at the Karolinska Institute, was an EMBO postdoc fellow at the Max Planck Institute for Biochemistry, Germany and then joined the lab of Prof Dame Carol V. Robinson at the Universities of Oxford and Cambridge, UK. In 2004, Leopold moved to Stockholm University as an Assistant professor and became Docent in 2009. He is a visiting Professor at the Medical University of Lublin, Poland; a Board member of the Swedish Mass Spectrometry Society and an Editorial Board member of Scientific Reports.


Currently Leopold is the course coordinator and a lecturer in Bioanalytical Chemistry. He participates in teaching the course Modern Methods in Chemistry and gives guest lectures in Molecular Biology. He also helped etablish a course in Analytical Chemical Ecology.

He was the Director of PhD studies in Analytical Chemistry (until end of 2019) and as such was involved in the PhD course in "Teaching Chemistry" . In 2020 he will be coordinator for a PhD course on Patents and Innovation.

He has graduated 10 PhD students and have had a number of MSc students.

For the past five years he has hosted guest interns from France, Italy, Colombia and Poland. 




Chemical analysis and structural characterization methods : 

    • Advanced analytical techniques for materials, environment and health

GAIA: Gas Phase Analyses of Intact Assemblies.

A project towards becoming a Sci Life Lab Infrastructure. This involves not only building up native mass spectrometry in Sweden but also involvement with the platform regarding the OMNITRAP (Fasmatech), a single ion trap component in which different gas phase activation techniques can be applied (Including collision induced dissociation, radical driven dissociation as well as photo-dissociation). This is in collaboration with Prof. Roman Zubarev.

Research projects on Native Mass Spectrometry 

Development of Native mass spectrometric methods for amyloids and analyses of non-covalent interactions, including the use of nanodiscs and other biomembrane mimics (collaboration with  DBB, SU and University of Leeds, UK). Ion mobility mass spectrometry with current projects on investigating gas phase structures involving cryo-mass spectrometry and infra-red spectroscopy (collaboration with AMGEN California, USA and the University of Lausanne).

Research projects on Novel Analytical Techniques 

Method development including electrocapture, carbon based solid-phase extraction, laser desorption strategies; new materials such as nanocomposites for ambient mass spectrometry and a new solvent assisted paper spray ionization method (in collaboration with KTH, Hong Kong Polytechnic and University of Parma and University of Salerno.

Research projects on Environmental Chemistry/Chemical Ecology

Development of strategies for identifying and monitoring environmental toxins with emphasis on BMAA and its isomers and related conjugates (in collaboration with ACES-X, SU);

IR/Raman Microscopy and bone biomaterials.

This is in cooperation with Dr. Habil Anna Sroka Bartnicka of Medical University of Lublin and Marie Curie Skolodowska University, Lublin, Poland. The work revolves around the application of an interdisciplinary approach using different complementary spectroscopic techniques vibrational spectroscopy (IR and Raman spectroscopy) and mass spectrometry (MALDI MSI) to study biological materials and biopolymers.

Fibrils, Biomembranes, Antimicrobials and NMR. 

This is in cooperation with Prof. Burkhard Bechinger ( Work has been on the structural elucidation of membrane interaction of cell penetrating peptides using both solution and solid-state NMR.

Funding: SciLife Lab (SU), Olle Engkvist Foundation, and 2 Swedish Research Council Grants (as co-applicant).

Current PhD Students (for alumni see ) :

Nicklas Österlund co-supervisee with Prof Astrid Graslund, DBB

Nikola Radoman co-supervisee with Prof Ian Cousins, ACES

Pedro de Sousa  co-supervisee with Docent Magnus Åberg

In Poland (PhD co-supervisees with Dr. Anna Sroka Bartnicka):

Grzegorz Kallis

Kasia Susniak

Mikoway Krysa

Current MSc students:

Monireh Kargar –Sharif (MSc student) external working at Karolinska Institute (with Prof Roman Zubarev)

Lovisa Österlind (Msc student) external working at the Doping Lab in Karolinska

Niklas Boden (MSc student) external working at the Doping Lab in Karolinska



A selection from Stockholm University publication database
  • 2019. Nicoló Riboni (et al.). Scientific Reports 9

    Paper Spray Ionization (PSI) is commonly applied for the analysis of small molecules, including drugs, metabolites, and pesticides in biological fluids, due to its high versatility, simplicity, and low costs. In this study, a new setup called Solvent Assisted Paper Spray Ionization (SAPSI), able to increase data acquisition time, signal stability, and repeatability, is proposed to overcome common PSI drawbacks. The setup relies on an integrated solution to provide ionization potential and constant solvent flow to the paper tip. Specifically, the ion source was connected to the instrument fluidics along with the voltage supply systems, ensuring a close control over the ionization conditions. SAPSI was successfully applied for the analysis of different classes of biomolecules: amyloidogenic peptides, proteins, and N-glycans. The prolonged analysis time allowed real-time monitoring of processes taking places on the paper tip, such as amyloid peptides aggregation and disaggregation phenomena. The enhanced signal stability allowed to discriminate protein species characterized by different post translational modifications and adducts with electrophilic compounds, both in aqueous solutions and in biofluids, such as serum and cerebrospinal fluid, without any sample pretreatment. In the next future, application to clinical relevant modifications, could lead to the development of quick and cost-effective diagnostic tools.

  • 2019. Nicklas Österlund (et al.). Journal of the American Chemical Society 141 (26), 10440-10450

    The mechanisms behind the Amyloid-beta (A beta) peptide neurotoxicity in Alzheimer's disease are intensely studied and under debate. One suggested mechanism is that the peptides assemble in biological membranes to form beta-barrel shaped oligomeric pores that induce cell leakage. Direct detection of such putative assemblies and their exact oligomeric states is however complicated by a high level of heterogeneity. The theory consequently remains controversial, and the actual formation of pore structures is disputed. We herein overcome the heterogeneity problem by employing a native mass spectrometry approach and demonstrate that A beta(1-42) peptides form coclusters with membrane mimetic detergent micelles. The coclusters are gently ionized using nanoelectrospray and transferred into the mass spectrometer where the detergent molecules are stripped away using collisional activation. We show that A beta(1-42) indeed oligomerizes over time in the micellar environment, forming hexamers with collision cross sections in agreement with a general beta-barrel structure. We also show that such oligomers are maintained and even stabilized by addition of lipids. A beta(1-40) on the other hand form significantly lower amounts of oligomers, which are also of lower oligomeric state compared to A beta(1-42) oligomers. Our results thus support the oligomeric pore hypothesis as one important cell toxicity mechanism in Alzheimer's disease. The presented native mass spectrometry approach is a promising way to study such potentially very neurotoxic species and how they could be stabilized or destabilized by molecules of cellular or therapeutic relevance.

  • 2019. Javier Zurita (et al.). Analytical Methods 11, 432-442

    β-Methylamino-L-alanine, a neurotoxin first isolated from the seeds of cycad tree Cycas circinalis, is widely spread in a variety of environments. New sensitive techniques and robust methodologies are needed to detect its presence in complex biological samples and to further understand its biochemical properties. In this context, the determination of the enantiomeric composition of natural BMAA is of great importance. In this study, a simple and easily implemented LC-ESI-MS/MS method was developed to determine the presence of both D- and L-BMAA enantiomers in samples of cycad seed (Cycas micronesica). The samples were subjected to enzymatic hydrolysis to avoid racemization that occurs during strong acid hydrolysis. Derivatization with (+)-1-(9-fluorenyl)-ethyl chloroformate (FLEC) was performed prior to LC-ESI-MS/MS to produce chromatographically separable derivatives of D- and L-BMAA. Together with the retention time, two MRM transitions and their peak area ratios were used to identify the compounds. The LOQ obtained was 0.3 μg BMAA per g wet weight for each enantiomer. Method repeatability was within 3 RSD% both intraday and interday and accuracy was 98–108%. An accurate enantiomeric composition was obtained from the samples of cycad seed, where L- and D-BMAA were detected at 50.13 ± 0.05 and 4.08 ± 0.04 μg BMAA per g wet weight respectively (n = 3).

  • 2018. Nicklas Österlund (et al.). ACS Chemical Neuroscience 9 (7), 1680-1692

    The amphiphilic nature of the amyloid-beta (A beta) peptide associated with Alzheimer's disease facilitates various interactions with biomolecules such as lipids and proteins, with effects on both structure and toxicity of the peptide. Here, we investigate these peptide-amphiphile interactions by experimental and computational studies of A beta(1-40) in the presence of surfactants with varying physicochemical properties. Our findings indicate that electrostatic peptide-surfactant interactions are required for coclustering and structure induction in the peptide and that the strength of the interaction depends on the surfactant net charge. Both aggregation-prone peptide-rich coclusters and stable surfactant-rich coclusters can form. Only A beta(1-40) monomers, but not oligomers, are inserted into surfactant micelles in this surfactant-rich state. Surfactant headgroup charge is suggested to be important as electrostatic peptide-surfactant interactions on the micellar surface seems to be an initiating step toward insertion. Thus, no peptide insertion or change in peptide secondary structure is observed using a nonionic surfactant. The hydrophobic peptide-surfactant interactions instead stabilize the A beta monomer, possibly by preventing self-interaction between the peptide core and C terminus, thereby effectively inhibiting the peptide aggregation process. These findings give increased understanding regarding the molecular driving forces for A beta aggregation and the peptide interaction with amphiphilic biomolecules.

  • 2019. Farshid Mashayekhy Rad (et al.). Journal of the American Society for Mass Spectrometry 30 (1), 161-173

    In this article, an analytical methodology to investigate the proteinaceous content in atmospheric size-resolved aerosols collected at the Zeppelin observatory (79 °N, 12 °E) at Ny Ålesund, Svalbard, from September to December 2015, is proposed. Quantitative determination was performed after acidic hydrolysis using ultrahigh-performance liquid chromatography in reversed-phase mode coupled to electrospray ionization tandem mass spectrometry. Chromatographic separation, as well as specificity in the identification, was achieved by derivatization of the amino acids with N-butyl nicotinic acid N-hydroxysuccinimide ester prior to the analysis. The chromatographic run was performed within 11 min and instrumental levels of detection (LODs) were between 0.2 and 8.1 pg injected on the column, except for arginine which exhibited an LOD of 37 pg. Corresponding method LODs were between 0.01 and 1.9 fmol/m3, based on the average air sampling volume of 57 m3. The sum of free amino acids and hydrolyzed polyamino acids was shown to vary within 6–2914 and 0.02–1417 pmol/m3 for particles in sizes < 2 and 2–10 μm in equivalent aerodynamic diameter, respectively. Leucine, alanine, and valine were the most abundant among the amino acids in both aerosol size fractions. In an attempt to elucidate source areas of the collected aerosols, 5- to 10-day 3D backward trajectories reaching the sampling station were calculated. Overall, the method described here provides a first time estimate of the proteinaceous content, that is, the sum of free and polyamino acids, in size-resolved aerosols collected in the Arctic.

Show all publications by Leopold Luna Ilag at Stockholm University

Last updated: February 18, 2020

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