Activity 2: Label-free optical spectroscopic analysis


Current proteomic analysis methods, including mass spectrometry, surface plasmon resonance and label assisted assays provide valuable information about the molecular content of various biological samples. This activitity aims to develop a label-free optical spectroscopic analysis method that has the potential for studying real-time molecular interactions, in particular post-translational modifications of proteins such as the effects of phosphorylation and glycosylation. The method is based on a modified evanescence spectroscopic method where we couple mid-infrared (IR) light into a thin diamond layer which act as a waveguide. The high refractive index of diamond compared to the surrounding media means that there will only leak out an evanescent wave penetrating a few microns above the waveguiding layer. In regions of the IR spectrum where the sample absorbs energy, the evanescent wave will be attenuated or altered. This feature is common to all evanescent spectroscopic methods. However, employing mid-IR light the transmitted signal will carry information about the specific fundamental vibrational properties of molecules adsorbed on the sensor surface. Moreover, the diamond layer is in our case fabricated on-board a microfluidic chip for signal multiplexing and sample handling. A particular attractive feature of nano crystalline diamon, which we will use in the present project, is that it offers several, and sometimes simpler, surface-to-ligand coupling strategies than currently feasible with e.g. silicon or gold sensing layers. Furthermore, diamond offers possibilities for easy sample preparation and regeneration due to its beneficial chemical and mechanical properties. We intend to first work with a class of well characterized proteins, in order to benchmark our new technology against existing methods. In a second step we plan to evaluate the analysis method for post-translational modifications of proteins, relevant in Alzheimer’s disease.






Project leader:






  • Fredrik Nikolajeff (UU)
  • Lars Österlund (Molecular Fingerprint)
  • Lars Lannfelt (UAS)
  • Joakim Bergström (UU)
  • Pär Gellerfors (BioArctic Neuroscience)






Uppsala Berzelii Technology Centre for Neurodiagnostics | Email