r is an amino acid, a dipeptide or a tripeptide with a C-terminus ???OH, NH2, or NH???R14; R14 is an aliphatic C1 to C17 chain; each X is a peptide chain that (i) has a minimum of three amino acid residues, (ii) has a maximum of about fifty amino acid residues, and (iii) binds a HBGFR; J1 and J2 are each independently a trifunctional alpha amino acid residue, wherein each X is covalently bonded th