In NHS/EDC protocol, there are two buffers. coupling buffer and activation buffer. (+washing buffer) And, I will conjugate PEG-COOH to amine-modified oligonucleotide.

In the NHS / EDC reaction protocol, the composition of the coupling buffer is shown but the composition of the activation buffer is not shown. In addition, all of these protocols are protocols for the conjugation of amine to -COOH in proteins, and there is no mention of what buffer to use when attaching an amine modified oligonucleotide to -COOH.

1. If the pH is kept between 8.5 and 9.5, does the activation buffer have a similar pH? What is the composition of the activation buffer?

2. In the case of the coupling buffer, the pH of the protein in the protocol is 6.0, which is higher than 7.2. Is it okay to use it as a coupling buffer for oligonucleotides (for immersing PEG particles)?

ps. If you have an EDC / NHS protocol for conjugation of the amino-modified oligonucleotide you have with -COOH (which is better for polyethylene glycol-COOH), I would appreciate it. Other reagents can not afford to buy.