Ultrashort Peptides and Gold Nanoparticles: Influence of Constrained Amino Acids on Colloidal Stability

Abstract

Poor colloidal stability of gold nanoparticles (AuNPs) in physiological environments remains one of the major limitations that contribute to their difficult translation from bench to clinic. For this reason, an active research field is the development of molecules able to hamper AuNPs aggregation tendency in physiological environments. In this context, synthetic peptides are gaining an increased interest as an alternative to the use of biomacromolecules and polymers, due to their easiness of synthesis and their profitable pharmacokinetic profile. In this work, we reported on the use of ultrashort peptides containing conformationally constrained amino acids (AAs) for the stabilization of AuNPs. A small library of non-natural self-assembled oligopeptides were synthesized and used to functionalize spherical AuNPs of 20 nm diameter, via the ligand exchange method. The aim was to investigate the role of the constrained AA, the anchor point (at C- or N-terminus) and the peptide length on their potential use as gold binding motif. Ultrashort Aib containing peptides were identified as effective tools for AuNPs colloidal stabilization. Furthermore, peptide coated AuNPs were found to be storable as powders without losing the stabilization properties once re-dispersed in water. Finally, the possibility to exploit the developed systems for binding proteins via molecular recognition was also evaluated using biotin as model.

Microalgae Peptide-Stabilized Gold Nanoparticles as a Versatile Material for Biomedical Applications

“…Moreover, the bands corresponding to pep-AuNPs showed significantly lower streaking due to the peptide’s capacity to stabilize and firmly wrap the AuNPs to protect them from clumping up [ 22 ]. Short peptides have been shown to dramatically increase the stability of the gold nanoparticles, even providing the possibility of being stored as dry powders without losing their properties after redispersion [ 51 ]. Because of the differences in sample migration, gel electrophoresis was a practical and straightforward method to observe and conclude tendencies of size dispersity, aggregation, stability, and proper modifications of nanoparticles in a single test.…”

Tuning Peptide-Based Hydrogels: Co-Assembly with Composites Driving the Highway to Technological Applications

“…The system showed very interesting catalytic activity in reducing small pollutants to less toxic compounds, which makes it promising for environmental technology applications [110]. It should also be noted that the conjugation of peptides with AuNPs is extremely advantageous, not only in the formulation of AuNPs-hydrogels, but also in addressing the major limitation of the latter, particularly in physiological environments, i.e., poor colloidal stability [111]. On the other hand, the work conducted so far on AgNPs-hydrogel composites focuses on the development of antibacterial materials [112][113][114][115][116] and the detection of analytes by surface-enhanced Raman scattering (SERS).…”

Radiolabeled Gold Nanoseeds Decorated with Substance P Peptides: Synthesis, Characterization and In Vitro Evaluation in Glioblastoma Cellular Models

“…This is a crucial issue, as AuNPs for biomedical applications need to be stable in physiological environments. If needed, several strategies can be employed to improve the colloidal stability of AuNPs gold nanoparticles, such as their functionalization with different biomacromolecules and polymers or with thiol-containing small peptides [ 29 , 30 , 31 ]. As we have previously shown for bombesin (BBN) derivatives, AuNP-TDOTA can be readily functionalized with bioactive peptides carrying an N-terminal thioctic acid function for their Au-S chemisorption through the terminal disulfide group [ 28 , 32 ].…”