Development of Self‐Assembling Mixed Protein Micelles with Temperature‐Modulated Avidities

Abstract

Elastin-like polypeptides (ELPs) are polypentapeptides that undergo hydrophobic collapse and aggregation above a specific transition temperature, Tt. ELP diblocks sharing a common “core” block (I60) but varying “outer” blocks (A80, P40) were designed, where Tt,I < Tt,A < Tt,P. The formation of ~55 nm diameter mixed micelles from these ELP diblocks was verified using dynamic light scattering (DLS), multiangle light scattering (MALS) and fluorescence resonance energy transfer (FRET). To confer affinity to the blood circulating protein fibrinogen, a fibrinogen-binding tetrapeptide sequence (GPRP) was fused to A80-I60, while P40-I60 was fused to a non-binding control (GPSP). The self-assembling, peptide-displaying, mixed micelles exhibit temperature-modulated avidities for immobilized and soluble fibrinogen at 32 °C and 42 °C. In this initial proof-of-concept design, the engineered mixed micelles were shown to disengage fibrinogen at elevated temperatures. The modular nature of this system can be used for developing in vivo depot systems that will only be triggered to release in situ upon specific stimuli.

Fibrin-based biomaterials: Modulation of macroscopic properties through rational design at the molecular level

“…These mimics can then be used alone, or in conjunction with carrier materials, to modify fibrin structure. We subsequently created a variety of knob mimic constructs including knob A -protein constructs, PEGylated knobs A and B and knob A modified elastin-like peptide (ELP) micelles and characterized their effect on fibrin properties such as polymerization, degradation and mechanical properties and network structure [31, 43, 151–153]. Knob A -protein constructs designed to display the tetrapeptide sequences GPRP, GPRV, GHRP or GSPE (non-binding control) at the N-termini of a protein fragment, specifically the cell binding 9th and 10th type III repeats of fibronectin, were found to stably bind fibrinogen via specific knob:hole interactions and were retained within fibrin matrices for 24 hours, therefore showing promise as a potential method for drug release from fibrin matrices [152].…”

Bifunctional Elastin-like Polypeptide Nanoparticles Bind Rapamycin and Integrins and Suppress Tumor Growth in Vivo

“…28 This is supported by a recent report, which confirmed the in vitro coassembly of two ELP diblock copolymers into mixed micelles, whereby one ELP-bound fibrinogen and a second ELP provided temperature-dependent reversal of binding. 47 To develop the first in vivo evidence that multiple ELP diblock copolymers can work together to improve the delivery of a small molecule, this manuscript describes two ELP diblock copolymer fusions (FSI and ISR) that assemble at physiological temperature into bifunctional nanoparticles (Figure 1). …”

Elastin‐Like Peptides (ELPs) – Building Blocks for Stimuli‐Responsive Self‐Assembled Materials

“…Soon et al [60] demonstrated a gradual, controlled selfassembly of ELP diblocks to micelles to micron-sized aggregates. Two types of diblocks were used in this study: I 60 40 .…”

“…Two types of diblocks were used in this study: I 60 40 . The A 80 block was decorated with a fibronectin binding group.…”