N-Acetylation of Biodegradable Supramolecular Peptide Nanofilaments Selectively Enhances Their Proteolytic Stability for Targeted Delivery of Gold-Based Anticancer Agents

Abstract

Peptide materials are promising for various biomedical applications; however, a significant concern is their lack of stability and rapid degradation in vivo due to non-specific proteolysis. For materials specifically designed to respond to disease-specific proteases, it would be desirable to retain high susceptibility to target proteases while minimizing the impact of non-specific proteolysis. We describe N-terminal acetylation as a simple synthetic modification of amphiphilic self-assembling peptides that contain an MMP-9-cleavable segment and form soluble, nanoscale filaments. We found that the N-terminus capping of these peptides did not significantly impact their self-assembly behavior, critical aggregation concentration, or ability to encapsulate hydrophobic payloads. By contrast, their proteolytic stability in human plasma (especially for anionic peptide sequences) was considerably increased while susceptibility to hydrolysis by MMP-9 was retained when compared to non-acetylated peptides, especially during the first 12 h. We note, however, that due to the longer time scale required for in vitro studies (72 h), non-specific proteolysis of both anionic acetylated peptides leads to similar activity in vitro despite differing MMP-9 kinetics during the early stages. Overall, the enhanced stability against non-specific proteases, combined with the ability of these nanofilaments to enhance the effectiveness of gold-based drugs toward cancerous cells compared to healthy cells, brings these acetylated peptide filaments a step closer toward clinical translation.

Development of immunoliposomes containing cytotoxic gold payloads against HER2-positive breast cancers

“…Cell viability studies are usually employed to asses toxicity of drugs encapsulated in nanocarriers. 43–46 we selected four cell lines for this study: two HER2-positive breast cancer cell lines, BT-474 and SKBR-3 (both with equal overexpression of HER242); a triple-negative breast cancer line, MDA-MB-231; and a non-cancerous lung fibroblast line, IMR-90. We first measured the IC 50 value of both 1 and 2 at 72 hours and found low micromolar values for all cell lines, with slightly higher toxicity for MDA-MB-231 (Fig.…”

MMP-responsive nanomaterials

“…Nanomaterials allow incorporation of additional factors to obtain greater control and tunability in achieving desired substrate specificity towards specific MMPs and increase proteolytic stability in samples like human plasma. 67 Thus, the second factor examines the morphology of nanostructures which can be arranged in such a manner that permits the MMPs to access the cleavable substrate, optimally mimicking the supramolecular context of the natural biological substrates of the target MMP. Lastly, the short-range electrostatic interactions between the nanoparticle and the enzyme can be tuned to optimize responsiveness.…”

Tuning Supramolecular Chirality in Iodinated Amphiphilic Peptides Through Tripeptide Linker Editing

“…Designed peptide sequences that self-assemble into nanostructures − continue to receive attention for biomedical applications. − We are interested in developing matrix metalloprotease (MMP)-activated peptide filaments − as theranostic agents, which will ultimately involve the direct labeling of peptides with a radioisotope of iodine. The systems are designed to undergo localized, hydrolysis-induced changes in dispersibility catalyzed by target MMPs that are overexpressed by cancer cells, thus giving rise to immobilization or precipitation of the radioisotope at the cancer site, which can function as a therapy or imaging agent.…”