Pros And Cons Of Using CM-5 Chips In SPR Analysis

1) Comment on the pros and cons of using CM-5 chips in SPR analysis (3 marks).

CM-5 chips can provide a relatively high carboxylation of dextran matrix which develops high negative-charged surface that contribute to bind large amount of ligands. However, the high negative-charged surface may increase the chance of non-specific binding of other stronger positively charged molecules causing false positive signals.

Covalent bound with the ligand through the EDC/NHS activation process which provides excellent chemical stability and tight immobilization onto the chip. There are multiple linkers available onto the chip, including -NH2, -SH, -CHO, -OH or –COOH groups for binding a target ligand. However, the strong binding of ligand on the CM-5 chip may lead to difficulty in dissociation of ligand from the chip (theoretically, it is not able to regenerate covalent-bound ligands from the chip).

CM-5 provides high capacity of binding area to analytes by its high density of ligand binding surface while it could be the possible risk factor to trigger the non-specific binding. The non-specific binding signals leads to inaccurate analysis of protein-protein interaction or kinetic study.

2) When a CM-5 chip is used, what parameters we have to optimize for the immobilization? (2 marks)

1.
Applying Bovine serum albumin (BSA) (up to 3%) in the rung buffer could be useful. It is can be loaded into the running buffer and run with the target analytes while a interaction analysis of BSA binding on SPR sensor chip is needed in order to eliminate the signal generated from BSA binding at the final calculation. BSA is the most preferred because it can efficiently block the non-specific binding and no significant harmful effect on to ligands and analytes (Acchione M, Shezifi D, 2013, Nicoya Lifesciences,