Gulistan's work with colleagues from Eindhoven on hierarchically structured liquid-crystal polymer networks as new biointerfaces accepted in Advanced Materials!
Shirish publishes FluidFM work with partners from ETH and provides quantitative insights on interactions between cells and supramolecular interfaces.
LipoCoat B.V. is formally established half way in 2016. This Twente startup develops unique coatings for medical devices such as contact lenses. The coatings are designed to improve performance, safety and comfort of medical devices.
Supramolecular Protein Immobilization on Lipid Bilayers
Protein immobilization on surfaces, and on lipid bilayers specifically, has great potential in biomolecular and biotechnological research. Of current special interest is the immobilization of proteins using supramolecular noncovalent interactions. This allows for a reversible immobilization and obviates the use of harsh ligation conditions that could denature fragile proteins. In the work presented here, reversible supramolecular immobilization of proteins on lipid bilayer surfaces was achieved by using the host–guest interaction of the macrocyclic molecule cucurbituril. A fluorescent protein was successfully immobilized on the lipid bilayer by making use of the property of cucurbituril to host together a methylviologen and the indole of a tryptophan positioned on the N-terminal of the protein. The supramolecular complex was anchored to the bilayer through a cholesterol moiety that was attached to the methylviologen tethered with a small polyethylene glycol spacer. Protein immobilization studies using a quartz crystal microbalance (QCM) showed the assembly of the supramolecular complexes on the bilayer. Specific immobilization through the protein N-terminus is more efficient than through protein side-chain events. Reversible surface release of the proteins could be achieved by washing with cucurbituril or buffer alone. The described system shows the potential of supramolecular assembly of proteins and provides a method for site-specific protein immobilization under mild conditions in a reversible manner.
In this work, the development of a photoresponsive platform for the presentation of bioactive ligands to study receptor–ligand interactions has been described. For this purpose, supramolecular host–guest chemistry and supported lipid bilayers (SLBs) have been combined in a microfluidic device. Quartz crystal microbalance with dissipation monitoring (QCM-D) studies on methyl viologen (MV)-functionalized oligo ethylene glycol-based self-assembled monolayers, gel and liquid-state SLBs have been compared for their nonfouling properties in the case of ConA and bacteria. In combination with bacterial adhesion test, negligible nonspecific bacterial adhesion is observed only in the case of methyl-viologen-modified liquid-state SLBs. Therefore, liquid-state SLBs have been identified as most suitable for studying specific cell interactions when MV is incorporated as a guest on the surface. The photoswitchable supramolecular ternary complex is formed by assembling cucurbituril (CB) and an azobenzene–mannose conjugate (Azo–Man) onto MV-functionalized liquid-state SLBs and the assembly process has been characterized using QCM-D and fluorescence techniques. Mannose has been found to enable binding of E. coli via cell-surface receptors on the nonfouling supramolecular SLBs. Optical switching of the azobenzene moiety allows us to “erase” the bioactive surface after bacterial binding, providing the potential to develop reusable sensors. Localized photorelease of bacterial cells has also been shown indicating the possibility of optically guiding cellular growth, migration, and intercellular interactions.
Supramolecular Surface Immobilization of Knottin Derivatives for Dynamic Display of High Affinity Binders
Knottins are known as a robust and versatile class of miniprotein scaffolds for the presentation of high-affinity binding peptides; however, to date their application in biomaterials, biological coatings, and surface applications have not been explored. We have developed a strategy to recombinantly synthesize a β-trypsin inhibitory knottin with supramolecular guest tags that enable it to adhere to self-assembled monolayers of the supramolecular host cucurbituril (CB). We have described a strategy to easily express knottins in E. coli by conjugating them to a fluorescent protein after which they are cleaved and purified. Knottin constructs that varied in the number and position of the supramolecular tag at either the N- or C-termini or at both ends have been verified for their trypsin inhibitory function and CB-binding properties in solution and on surfaces. All of the knottin constructs showed strong inhibition of trypsin with inhibition constants between 10 and 30 nM. Using microscale thermophoresis, we determined that the supramolecular guest tags on the knottins bind CB with a Kd of ∼6 μM in solution. At the surface, strong divalent binding has been determined with a Kd of 0.75 μM in the case of the knottin with two supramolecular guest tags, whereas only weak monovalent binding occurred when only one guest tag was present. We also show successful supramolecular surface immobilization of the knottin using CB and prove that they can be used to immobilize β-trypsin at the surface.
The review paper with the title "Effects of variations in ligand density on cell signaling" from Tushar Satav has been accepted in Small. It was regarded very urgent and will be highlighted in Materials View.
Multiple simultaneous interactions between receptors and ligands dictate extracellular and intracellular activities of cells. The concept of programmable ligand display is generally used to study the interaction between ligands at various densities displayed on surfaces with receptors present on cell surfaces. Various strategies are discussed here to display ligands on surfaces to study their effect on cell behavior. Only very few strategies have been reported where this display combines precise control over density with lateral spacing of ligands on surfaces. In this review we discuss selected examples of strategies to control ligand density and spacing and their implications for biological functions of cells.
Jasper receives the first investment from new UT investment fund. LipoCoat is a high tech start-up company that was founded by Jasper van Weerd, Marcel Karperien and Pascal Jonkheijm. The funding was awarded by Neelie Kroes, special envoy of the startup delta and renowned former politician in both the national government and European parliament
More on the UT investment fund and the first awarding can be found on the news page of the website of the University of Twente: http://www.utwente.nl/en/news/!/2015/6/415072/twente-launches-new-investment-fund-dutch-student-investment-fund
"UT RESEARCH OPENS THE WAY TO LIVING IMPLANTS"
was the heading of an article on the website of the
University of Twente that referred to Shrikrishnan’s
article of in ACS Nano.
“AANGELIJNDE BACTERIE, Twentse modificatie zet medicijnfabriekje vast op implantaat”
(TETHERED BACTERIA, a modification designed in Twente attaches medicine-factories to implant)
Headed C2W (Dutch biweekly magazine about chemistry and life-science)
The original articles can be found following these links: