Methods for the preparation of multivalent constructs for therapeutic and diagnostic applications are provided. More specifically, novel methods for preparing multivalent constructs comprising the formula A-B-C-D-E-B'-F for therapeutic and diagnostic applications are provided which use a novel linker D comprising, in various embodiments, a dicarboxylic acid derivative such as, e.g., a glutaric acid bis N-hydroxysuccinimidyl ester or a derivative thereof; or a diamine derivative.The remaining components in the multivalent construct A-B-C-D-E-B'-F are defined as follows: A is a first peptide, B is a first branching group, C is an optional first spacer, E is an optional second spacer which may be the same as or different from said first spacer C, B' is an optional second branching group which may be the same as or different from said first branching group B, and F is a second peptide which may be the same as or different from said first peptide A.