Abstract: A peptide derivative selected from a list of peptide derivatives with a sequence derived from human serum albumin fragment EPI-X4 is provided, which binds to CXCR4 with about 1000-fold stronger efficiency than EPI-X4. The peptide derivatives comprise length variants as well as modifications by length variants, D-amino acids, coupling of fatty acids, cholesterol or polymers, acetyl substitutions of amino groups, amination of carboxyl groups. Further provided are pharmaceutical compositions of the peptide derivative.

Abstract: Materials and methods for targeted and controlled addition of polymers to proteins are provided herein. For example, the methods provided herein can include contacting a protein with (i) an inactive controlled radical polymerization (CRP) initiator blocker that can reacts with amino groups on the protein but cannot serve as an initiator for polymer addition, and (ii) an active CRP initiator that reacts with amino groups on the protein and also includes a group through which a polymer can be coupled to the initiator.