After the coupling reaction (antibody-oligo), we used a Nanodrop ND-1000 to test the absorbance of the coupling products. We first tested the absorbance at 354 nm (user manual); we wanted to confirm if the conjugation was successful. We did not observe strong absorbance there, so we tested the absorbance of the product.

Posted on by

The 354 absorbance is small compared to the oligo A260 but what you have is reasonable. You can quantify the number of oligos attached using the extinction coefficient of the oligo (from the product data sheet, molar extinction coefficient at A354 is 29,000). Note the protein does not contribute much to the A260 so it can be ignored unless you want to be very accurate. Determine the protein concentration with a BCA assay. With those numbers, you can accurately determine the number of oligos/antibody.