Biointerfaces: Enabling Technology for Bio-Research

In collaboration with research groups from PSI and Universities we are developing surfaces for application in biomolecular and biomaterials research ranging from protein patterns on wafer, glass and polymer surfaces to micro- and nanostructured surfaces and templates for replication in biocompatible polymers.

Specific projects

Fluorescent-labeled biofunctionalized polymer brush structure
Copolymer brush structures grafted from the surface of polymer foils after functionalization with biotin and fluorescent labeled streptavidin.

Polymer brush structures for biosensor applications     
Based on our earlier work on polymer micro- and nanografting, we are exploring the potential of polymer brush structures for applications as bio-interfaces. In particular, we’re grafting copolymers consisting of hydrophilic units with antifouling properties and monomer that can easily biofunctionalized from the surface of polymer foils. Biofunctionalization is currently focused towards biosensor applications and includes binding of enzymes, linker proteins such as streptavidin and DNA.

 

Polymer support for SFX
A 3 µm thick perforated COC film is suspended in a 5 x 5mm sized polymer frame and fixed on a pin as used for protein crystallography. The SEM images on the right show 3 µm sized perforations in the membrane generated with nanoimprint lithography.

Supports for Serial Protein Crystallography     Serial femtosecond crystallography based on X-ray free-electron laser sources (XFELs) provides new opportunities for structural sciences, in particular for the time-resolved investigation of dynamic processes. High efficiency measurements at XFELs using the so-called fixed-target approach require very well ordered high-density deposition of protein micro-crystals on a substrate, which is positioned on a moveable stage and scanned through the (fixed) laser beam. We develop silicon- and polymer-based supports which are optimized for easy protein crystal deposition and low x-ray background, and which are suitable to perform pump-probe experiments.

References: 
I. Martiel et al., Versatile microporous polymer-based supports for serial macromolecular crystallography, Acta Cryst. (2021). D77, 1153–1167, doi: 10.1107/S2059798321007324.

A. Karpik, I. Martiel, P.M. Kristiansen and C. Padeste, Fabrication of ultrathin suspended polymer membranes as supports for serial protein crystallography, Micro and Nano Engineering 7 (2020) 100053, doi: 10.1016/j.mne.2020.100053.

Earlier Projects

Neuron cells cultured on a structured substrate
Outgrowth of neurites from primary rat neurons guided by a structure of parallel ridges.

Substrates for ultrastructural studies     We are developing patterned supports for neuron cell co-cultures with the aim to replicate the neuronal pathway under controlled conditions for subsequent use in ultrastructural studies of Parkinson’s Disease (PD). The lithographically structured substrates are compatible with a cryo-ultrastructural analysis workflow consisting of high pressure freezing, freeze substitution and preparation for electron microscopy. The aim is to understand the ultrastructure of PD-associated sub-cellular aggregates and intracellular components within diseased synapses, axons and neuronal bodies, in order to design better therapeutic strategies and ways to potentially monitor and detect the disease at an early stage. Our well-designed cell culture model can provide key insights while circumventing complex issues associated with handling whole human brain tissue.

Reference: Tran HT, Lucas MS, Ishikawa T, Shahmoradian SH and Padeste C (2021) A Compartmentalized Neuronal Cell-Culture Platform Compatible With Cryo-Fixation by High-Pressure Freezing for Ultrastructural Imaging. Front. Neurosci. 15:726763. doi: 10.3389/fnins.2021.726763

Functionalized microneedle integrated into an optofluidic sensor device
Functionalized microneedle integrated into an optofluidic sensor device

Integrated microneedle-optofluidic biosensor     In an international collaboration between the University of the British Columbia (UBC) and the Paul Scherrer Institut (PSI), a promising system for painless and minimally-invasive therapeutic drug monitoring has been demonstrated. The proposed device is based on the combination of an optofluidic system with hollow microneedles to extract extremely small volumes (< 1 nL) of interstitial fluid (ISF) to measure drug concentrations.  >>read more
 

Alignment of PAE cells cultured on a pattern of VEGF
Alignment of PAE cells cultured on a pattern of VEGF

VEGF-Patterns     Based on photolithograpghy or on microfluidics we were producing patterns of proteins of the VEGF-Family. Studies of porcine aortic endothelial cells (PAE cells) cultured on the substrates enable new insights into the mechanisms deteriming blood vessel formation which are highly dependent on the presence and distribution of VEGF-proteins. In collaboration with Kurt Ballmer, molecular cell biology at PSI.
 

Growth of NSCs on pillar arrays replicated in biocompatible PLLA/PLGA-copolymers. The cells align along the most dense packing of nanopillars.
Growth of NSCs on pillar arrays replicated in biocompatible PLLA/PLGA-copolymers. The cells align along the most dense packing of nanopillars.
Nanopillar arrays for cell growth studies    In a collaboration with the "Biomaterials and Tissue Engineering Research Laboratory" (BIOMAT), METU, Ankara, we designed and produced of arrays of 200 nm to 1 µm wide and 1 to  5 µm tall pillars with pillar-to-pillar distances in the range of 1-10 µm. The pillar arrays were replicated into biocompatible polymers and are being used in cell growth experiments performed at METU. Studies of cell adhesion and proliferation of different cells depending on the pillar size and inter-pillar distances deliver valuable information for the design of medical implant surfaces.

Contact

Dr. Celestino Padeste

Lab. of Nanoscale Biology
Paul Scherrer Institut
Forschungsstrasse 111
5232 Villigen PSI
Switzerland

Telephone:
+41 56 310 2141

E-mail:
celestino.padeste@psi.ch