SPR stands for Surface Plasmon Resonance, which is a technique that detects biomolecular interactions and can provide valuable data about them, including providing kinetics/affinity characterisation and screening. Typically, SPR involves shining a polarised light source through a prism onto an electrically conducting chip surface (usually gold). The light beam reflects off the chip at a specific incident angle (also known as the resonant angle) into a detector. The biomolecules of interest can then interact on this chip and if a binding event occurs the light beam’s incident angle will change as the chip surface has been changed. The detector now receives this new angle indicating that a binding event has occurred, and vital information can be gathered from the differences in these recorded angles.
SPR at Nicoya
Our partner company Nicoya uses the principles described above in their OpenSPR and Alto Instruments. The sensor chip they use is a gold film coated on a glass substrate, which is modified to allow ligands to be immobilised onto it. During experimentation a solution containing the analyte is passed over the chip and allows the analyte to bind to the immobilised ligands. The analyte can also be washed away using a buffer solution leaving the immobilised ligands alone on the chip, so they can provide association and dissociation data of biomolecular interactions. However, as previously seen these binding events change the incident angle which is captured by the detector but at Nicoya they obtain the kinetics data from changes in the refractive index, due to their use of LSPR rather than regular SPR.
What is LSPR?
LSPR also known as localised surface plasmon resonance uses the same principles seen above but rather than one continuous film of gold, the glass coated substrate is covered in metal nanoparticles of gold. This produces a strong resonance absorbance peak which is highly sensitive to the local refractive index and any changes it may experience due to binding events.
So, for the OpenSPR and Alto it is the small changes in wavelength of the absorbance position which are measured by the detector rather than the incident angle produced by the reflected polarised light. This gives the LSPR system several advantages, which include:
LSPR on The Alto
On top of using LSPR technology, the Alto system also uses digital microfluidics with nanotechnology-based biosensors, which provide further advantages as the system is designed to be user-friendly and accessible. Find out more about SPR and Nicoya’s OpenSPR and Alto systems here. If you are interested in any of these systems or are looking for contract testing for binding kinetics data please contact us.