Promotor: J.G.E.M. Fraaije, Co-Promotor: A. Kros

Alexander Kros and co-workers describe how mesoporous silica nanoparticles (MSNs) are delivered into cells via membrane fusion thereby omitting endocytosis pathways. Fusion is induced by a pair of complementary coiled-coil lipopeptides inserted into the membrane of cells and in the bilayer of lipid-coated…

How can the transport of molecules in living cells help to target medicines at exactly the right place?

Promotor: J.G.E.M.Fraaije, Co-promotor: A. Kros

The European Research Council (ERC) has awarded chemist Dr Alexander Kros a Starting Independent Researcher Grant of 1.4 million euro. He will be using the grant to study how molecules penetrate the natural barrier of a cell membrane. If his research is successful, it will in time bring about a revolution…

The thesis describes the use of electron paramagnetic resonance (EPR) spectroscopy, in continuous wave and pulse modes, to address the interaction of α-Synuclein (αS) with membranes and the aggregation of αS.

Membrane fusion is a vital process in living organisms and is mediated by zipper-like proteins.

Promotor: A. Kros

A structural investigation of coiled coil peptides used as membrane fusogens, mimicing naturally occuring coiled-coil fusion proteins. Synthetic modifications have been made to alter lipid attachment, secondary structure and to insert photoactive azobenzene moieties for active control over coiled coil…

This dissertation contains four works during my PhD. Different biomaterials have been designed based on coiled-coil peptides. These biomaterials have a range of applications, inclusing drug delivery, cell sorting to cell-cell fusion.

Membrane proteins and membrane interactions of proteins are studied by spin label EPR. Intact, native membranes, vesicles of all sizes and nano-disks can be investigated, because the size of the object does not matter in EPR. Whereas solution NMR is limited to micelles (a few nm in diameter), by EPR…

Promotor: J.G.E.M.Fraaije, Co-promotor: A. Kros

Is there a sufficiently large market for drug screening and testing in Zebrafish larvae using membrane fusion?

Promotor: A. Kros, Co-promotor: R.R.C.L. Olsthoorn

Multicellular giant algae Chara species have been widely used in physiological studies for decades.

Many biological processes occur by biomolecules coming together and organizing into specific clusters without being bound to each other. These interactions range from clustering, transiently interacting (kiss and run), or assembling to multimeric units that can only function in conjunction. The hydrogen…

The plant hormone auxin plays a central role in the growth and development of plants. Auxin acts in a concentration dependent manner and polar cell-to-cell transport of this hormone determines its distribution in the tissues of plants. This polar auxin transport is mediated by several families of auxin…

Promotor: M. Ubbink, Co-promotor: G. Siegal

Alexander Kros studies supramolecular systems in a biological environment. The unifying theme between the projects in my lab is specific molecular recognition, i.e. the intermolecular interaction between complementary molecules with high affinity and selectivity. Studying, imitating and dissecting processes…

The current resurgence of whooping cough is alarming, and improved pertussis vaccines are thought to offer a solution. Outer membrane vesicle vaccines (omvPV) are potential vaccine candidates, but omvPV-induced humoral responses have not yet been characterized in detail.

The Supramolecular & Biomaterials Chemistry group comprises the PIs Alexander Kros, Roxanne Kieltyka, Gregory Schneider and Sander Wezenberg, and is active in the field of self-assembly of amphiphilic peptides and applying them in supramolecular chemistry.

The skin barrier function is provided by the stratum corneum (SC). The lipids in the SC are composed of three lipid classes: ceramides (CERs), cholesterol (CHOL) and free fatty acids (FFAs) which form two crystalline lamellar structures. In the present study, we investigate the effect of CER chain length…

Congres/symposium

Barrier function is the natural role of the skin. The lipid matrix present in the outermost layer of the skin, the stratum corneum is important for this function.

Promotor: J. A. Bouwstra

Source: International Journal of Cosmetic Science, Volume 37, Number 1, pp. 158-158 (2015) ISBN: 0142-5463

The effectiveness of the skin barrier underlies the outer layer of the skin: the stratum corneum (SC). However, in several skin diseases this barrier is impaired. In two inflammatory skin diseases, atopic eczema and Netherton syndrome, an increased level of monounsaturated fatty acids (MUFAs) has been…

Research at the SBC group is comprised of the following research themes:

The stratum corneum (SC) plays a fundamental role in the barrier function of the skin. The SC consists of corneocytes embedded in a lipid matrix.

The connection between programming and reading seems non-existing. Yet in the new reading book ‘De Programmeerbende’ they go together very well. On 26 February author Inge Strijker and co-inventor and computer scientist Felienne Hermans launched the book at the Leiden Institute of Advanced Computer…

Chemical biology research at the Leiden Institute of Chemistry is aimed at understanding biological processes at the molecular level to strengthen the knowledge base of human health and disease. The approach to achieve this goal is a fundamental chemical one; with the aid of chemical probes biological…

Leiden chemists have created a new ultrathin membrane only one molecule thick. The membrane can produce a hundred times more power from seawater than the best membranes used today. The researchers have published their findings in Nature Nanotechnology.

The lipid membrane is a basic structural component of all living cells. Embedded in this nanometer-thin barrier, membrane proteins shape the membrane and at the same time respond to the shape of the membrane.

Α-synuclein, a protein associated with Parkinson’s disease, proves to bind with membranes in a surprisingly efficient way. It confirms scientists’ suspicion of the protein’s leading role in the transmission of neurotransmitters between nerve cells in the brain. Publication in PLoS ONE.

Solar energy harnessed by plants and algae has great potential to be converted into biofuels for future generations.

Light-Harvesting Complex II (LHCII) is responsible for light absorption and excitation energy transfer in plants and photosynthetic algae, while in high light it undergoes conformational changes by which it quenches excitations to prevent photodamage.

Promotor: J.N. Kok, Co-promotor: H.J. Hoogeboom

My PhD thesis investigates the ecological significance of resistance against drought-induced air bubble formation inside the water conduits of plants (embolism), and the plasticity and functional aspects of stem anatomical traits in woody and herbaceous species.

Chemist Alexander Kros and astronomer Joop Schaye are two of the four Leiden researchers who have been awarded a Vici as part of NWO's Innovation Research Incentives scheme. They each have 1.5 million euros to set up a research group and employ PhD candidates.

This dissertation provides a novel perspective on the interaction between quantifier scope and ellipsis. It presents a detailed investigation of the scopal interaction between English negative indefinites, modals, and quantified phrases in ellipsis. One of the crucial observations is that a negative…

A full overview of BPOC/SSNMR PhD theses.

Can effective synergists be identified to enhance the effect of antibiotics against Gram negative pathogens?

Promotores: Prof.dr. H. S. Overkleeft, Prof.dr. G. A. van der Marel

Plants, are sessile organisms, have developed strategies to adapt to changes in their environment, in part by altering their growth and development.

Plants, algae and cyanobacteria have the amazing capacity to perform delicate photophysical and photochemical processes of light capture, excitation transfer, charge separation and catalysis in fluctuating living environments. As a consequence, photosynthetic proteins and membranes form dynamic architectures.…

Like a mixture of oil and water, lipid membranes separate into two liquid phases.

A selection of recent publications from the Plant BioDynamics Laboratory.