Collagen Targeting Using Protein-Functionalized Micelles: The Strength of Multiple Weak Interactions

Abstract

Collagen is an important marker for the assessment of tissue remodeling, both in normal tissue maturation and in a variety of prevalent disease processes. Given the importance of multivalency in the natural interactions of collagen, multivalent ligands provide unique opportunities to target collagen architectures. Here, we explored the use of micelles as dynamic self-assembling multivalent scaffolds for the collagen binding protein CNA35. Despite the increased popularity of micelles as nanosized carriers in targeted drug delivery and molecular imaging, few studies have actually directly addressed the importance of multivalent interactions for micelle-based targeting. Native chemical ligation was used as a chemoselective and efficient method to prepare relatively well-defined and stable micelles with a tunable average protein content between 0 and 20 copies of CNA35 per micelle. The thermodynamics and kinetics of CNA35 micelle binding to collagen was studied using solid-phase and surface plasmon resonance assays. Multivalent interactions between the micelles and collagen had a remarkable effect on micellar stability, since no dissociation of collagen-bound micelles was observed even after extensive washing. In addition, an impressive enhancement of collagen affinity was observed both in vitro and ex vivo resulting from multivalent display of a so-called "nonbinding" variant of CNA35. This "restoration" of collagen affinity was subsequently also observed for liposomes displaying the same low-affinity CNA35 variant at a sufficient density. These results demonstrate the importance of multivalent interactions for micelle-based targeting and illustrate the strength of multiple weak interactions when targeting intrinsically multivalent extracellular matrix (ECM) proteins such as collagen.

Peptide-functionalized nanoparticles for selective targeting of pancreatic tumor

“…Figure S5). The more important ligand-receptor interaction observed with CKAAKN-functionalized nanoparticles, as compared with the free peptide, demonstrated that the affinity of phage-display-derivated peptides can be significantly enhanced thanks to the multivalent interactions offered by a scaffold-like nanosized material in concordance with previous observations [33,34]. Although peptides present several advantages in comparison to other targeting homing devices (i.e., easy of synthesis and low immunogenicity), they usually possess modest target affinity.…”

“…Although peptides present several advantages in comparison to other targeting homing devices (i.e., easy of synthesis and low immunogenicity), they usually possess modest target affinity. However, the conjugation of multiple copies of targeting ligand onto the nanocarrier surface, allows overcoming this limitation by enabling multivalent interaction with high binding constants and improving targeting efficacy [33]. These results allowed identifying the biological target of the CKAAKN peptide confirming also its surface localization.…”

Collagen targeting using multivalent protein-functionalized dendrimers

“…In one approach peptide phage display was used to identify linear 7-mer peptides with a moderate affinity for collagen type I. 25 Multivalent display of this peptide on a pentavalent dendritic AB 5 scaffold was shown to successfully mimic the multivalent architecture of the peptides displayed on the original phage, resulting in a 100-fold increase in collagen affinity. Another demonstration of the potency of multivalent interactions was provided by a second study that used micelles and liposomes as multivalent scaffolds for the collagen binding protein CNA35.…”

“…Another demonstration of the potency of multivalent interactions was provided by a second study that used micelles and liposomes as multivalent scaffolds for the collagen binding protein CNA35. 14,25 This well-characterized collagen binding protein binds various types of collagen with a K d of 0.5 lM by wrapping around the collagen triple helix 26 and was shown to be a useful probe to monitor collagen formation in tissue engineering and in atherosclerotic plaques. 27 decrease the dissociation rate of these micelles in surface plasmon resonance binding (SPR) studies, being stable for more than 8 h under conditions of continuous flow.…”

Protease‐Activatable Collagen Targeting Based on Protein Cyclization

“…[8,[21][22][23][24] Collagen contains a high density of CNA35 binding sites, allowing fluorescent imaging of collagen without the need to remove non-bound CNA35. [21,23] Here we report circularization of CNA35 as a new approach to generate a dual-specific collagen-targeting probe that only binds collagen after activation by MMP1.…”