问题1：荧光微球的粒径多大？
2：为什么要加2-巯基乙醇？
我做过羧基微球直接与抗体偶联的试验，直接用EDC，偶联效率在95%以上。

先把微球和NHS放在一起加溶剂，溶解NHS，然后在冰浴下缓慢滴加EDC，可以把EDC先溶解稀释缓慢滴加，然后在慢慢回温，其实加水就可以淬灭EDC了，不需要加巯基乙醇，多臭啊
加入抗体后多反应一点时间，反应个过夜或者8h再试试吧

http://pubs.acs.org/doi/abs/10.1021/ac303204q
Approximately 5 mg of MNS or FNS were activated
in 100 mM EDC and 100 mM NHS in l mL of 0.01 M PBS
(pH 6.8) at room temperature with continuous shaking. After
incubating for 30 min, MNS were separated by magnetic force,
and FNS by centrifugation, and washed with 0.01 M PBS (pH
7.2) three times. Then, they were dispersed in 1 mL of 0.01 M
pH 7.2 PBS to react with 2 mg of NH2−PEG−CM for about 4
h at room temperature with continuous shaking. Afterward, the
resultant MNS−PEG−COOH and FNS−PEG−COOH were
washed by 0.01 M PBS (pH 7.2) five times to remove any
unreacted NH2−PEG−CM. Then, MNS−PEG−COOH and
FNS−PEG−COOH were reacted with the antibodies to S.
typhimurium (about 50 μg), and the conjugation procedure was
similar to that above except that the NH2−PEG−CM were
replaced by antibodies，