pH-Responsive Elastin-Like Polypeptide Designer Condensates

Understanding the Phase Behavior of a Multistimuli-Responsive Elastin-like Polymer: Insights from Dynamic Light Scattering Analysis

Elastin-like polymers are a class of stimuli-responsive protein polymers that hold immense promise in applications such as drug delivery, hydrogels, and biosensors. Yet, understanding the intricate interplay of factors influencing their stimuli-responsive behavior remains a challenging frontier. Using temperature-controlled dynamic light scattering and zeta potential measurements, we investigate the interactions between buffer, pH, salt, water, and protein using an elastin-like polymer containing ionizable lysine residues. We observed the elevation of transition temperature in the presence of the common buffering agent HEPES at low concentrations, suggesting a "salting-in" effect of HEPES as a cosolute through weak association with the protein. Our findings motivate a more comprehensive investigation of the influence of buffer and other cosolute molecules on elastin-like polymer behavior.

Contribution of the ELRs to the development of advanced in vitro models

Developing in vitro models that accurately mimic the microenvironment of biological structures or processes holds substantial promise for gaining insights into specific biological functions. In the field of tissue engineering and regenerative medicine, in vitro models able to capture the precise structural, topographical, and functional complexity of living tissues, prove to be valuable tools for comprehending disease mechanisms, assessing drug responses, and serving as alternatives or complements to animal testing. The choice of the right biomaterial and fabrication technique for the development of these in vitro models plays an important role in their functionality. In this sense, elastin-like recombinamers (ELRs) have emerged as an important tool for the fabrication of in vitro models overcoming the challenges encountered in natural and synthetic materials due to their intrinsic properties, such as phase transition behavior, tunable biological properties, viscoelasticity, and easy processability. In this review article, we will delve into the use of ELRs for molecular models of intrinsically disordered proteins (IDPs), as well as for the development of in vitro 3D models for regenerative medicine. The easy processability of the ELRs and their rational design has allowed their use for the development of spheroids and organoids, or bioinks for 3D bioprinting. Thus, incorporating ELRs into the toolkit of biomaterials used for the fabrication of in vitro models, represents a transformative step forward in improving the accuracy, efficiency, and functionality of these models, and opening up a wide range of possibilities in combination with advanced biofabrication techniques that remains to be explored.

Peptide-Mediated Nanocarriers for Targeted Drug Delivery: Developments and Strategies

Effective drug delivery is essential for cancer treatment. Drug delivery systems, which can be tailored to targeted transport and integrated tumor therapy, are vital in improving the efficiency of cancer treatment. Peptides play a significant role in various biological and physiological functions and offer high design flexibility, excellent biocompatibility, adjustable morphology, and biodegradability, making them promising candidates for drug delivery. This paper reviews peptide-mediated drug delivery systems, focusing on self-assembled peptides and peptide-drug conjugates. It discusses the mechanisms and structural control of self-assembled peptides, the varieties and roles of peptide-drug conjugates, and strategies to augment peptide stability. The review concludes by addressing challenges and future directions.

Unravelling the Mechanism of Elastin-like Polypeptide-Enzyme Fusion Stabilization in Organic Solvents

Elastin-like polypeptides (ELP) are a class of materials that are widely used as purification tags and in potential therapeutic applications. We have used the hydrophobic nature of ELP to extract them into organic solvents and precipitate them to obtain highly pure materials. Although many different types of ELP have been rapidly purified in this manner, the underlying mechanism for this process and its ability to retain functional proteins within organic phase-rich media has been unclear. A cleavable ELP-Intein construct fused with the enzyme chorismate mutase (ELP-I-Cm2) was used to better understand the organic solvent extraction process for ELP and the factors impacting the retention of enzyme activity. Our extraction studies indicated that a cell lysis step was essential to stabilize the ELP-I-Cm2 in the organic phase, prevent intein cleavage, and extract the fusion protein with high efficiency and retained activity. Circular dichroism and infrared spectroscopic characterization of ELP-I-Cm2 in organic solvents and aqueous solutions of the extracted and precipitated material indicated that the ELP secondary structure was retained in both environments. Atomic force microscopy and negative stain transmission electron microscopy imaging of ELP-I-Cm2 in organic solvents revealed highly regular circular features that were ∼50 nm in diameter, in contrast to larger (>100 nm) irregular features found in aqueous solutions. Since reverse micelles have often been used in catalytic processes, we evaluated the enzymatic activity of the ELP-I-Cm2 reversed micelles in different organic solvent mixtures and found that Cm2-mediated reactions in organic media were of comparable rate and efficiency to those in aqueous media. Based on these findings, we report an exciting new opportunity for ELP-enzyme fusion applications by exploiting their ability to form catalytically active reverse micelles in organic media.