Patent ID: 8889657

Claim:
A compound of the formula: wherein each L 1 , L 2 , L 3 and L 4 is independently selected from the group consisting of a bond and a linking group; R 1 is selected from the group consisting of a nanoparticle, an attachment component, a targeting agent, a diagnostic agent, a stealth agent, and a tetrapodal presentation component; each R 2 is independently selected from the group consisting of a stealth agent, C 1 -C 10 alkyl, a carboxylic acid or ester, a phosphonic acid or ester, a sulfonic acid or ester, and a hydroxy; each R 3 and R 4 is independently selected from the group consisting of H, a nanoparticle, an attachment component, a targeting agent, a diagnostic agent, and a stealth agent, wherein at least one of R 3 or R 4 is other than H; and n is an integer of from 0 to 2.