Patent ID: 7816315

Claim:
A compound comprising: a bifunctional material containing an amino group and a carboxyl group, wherein the bifunctional material has formula 1 or 2, wherein n is an integer from 1 to 10, A is wherein x is O, CO, S, SO 2 , CH 2 , C(CH 3 ) 2 or C(CF 3 ) 2 , or wherein a carbonyl group and a carboxyl group may be substituted on any carbon position except for a linking portion of the rings, and Y is wherein R 1 and R 2 may be identical or different and each is independently selected from the group consisting of a —OH group and a —NH(CH 2 ) n Y group, wherein n is an integer from 1 to 10 and Y is a nitrogen containing heterocycle base, R 3 is a C 1-10 alkyl group, and 1 is an integer from 1 to 30,000.