Gold thickness layer sensitivity affect

Hello,

As I read from the literature the gold thickness layer can affect the sensitivity of the measurement, so because the Biacore sensor chip is already optimized to get the best signal so I have confused with one thing

Does the ligand size (nm) will affect the thickness and the sensitivity of the Au layer chip?
for example, If the Au chip layer is 50nm and I conjugated a ligand that has 100nm size to the gold chip so the total thickness will be 150nm and then the sensitivity will decrease.

or the bigger ligand Mwt should enhance the signal because of bigger wavelength shifting after analyte recognition?

Thanks in advance 
 

Hi,
The thickness of the gold layer is of importance in coupling the light to obtain the surface plasmons. By doing so a fraction of the incident light is used and that is what is measured as a dip in the light spectrum. The coupling also generates an evanescent wave which extends for about one wavelength. Adsorbing molecules to the surface will not impact the spr-signal in the way you state but will -in case of a Biacore- shift the angle of the spr-minimum.

Arnoud