Self-Assembling Peptidic Bolaamphiphiles for Biomimetic Applications

Enhanced Photocatalytic Oxygen Evolution Using Copper-Coordinated Perylene Diimide Nanorod Assemblies

A crystalline supramolecular photocatalyst is prepared through metal-induced self-assembly of perylene diimide with imidazole groups at the imide position (PDI-Hm). Exploiting the metal-coordination ability of imidazole, a crystalline assembly of copper-coordinated PDI-Hm (CuPDI-Hm) in a nanorod shape is prepared which displays an outstanding photocatalytic oxygen evolution rate of 25,900 μmol g-1 h-1 without additional co-catalysts. The imidazole-copper coordination, along with π-π stacking of PDI frameworks, guides the arrangement of PDI-Hm molecules to form highly crystalline assemblies. The coordination of copper also modulates the size of the CuPDI-Hm supramolecular assembly by regulating the nucleation and growth processes. Furthermore, the imidazole-copper coordination constructs the electric field within the PDI-Hm assembly, hindering the recombination of photo-induced charges to enhance the photoelectric/photocatalytic activity when compared to Cu-free PDI-Hm assemblies. Small CuPDI-Hm assembly exhibits higher photocatalytic activity due to their larger surface area and reduced light scattering. Together, the Cu-imidazole coordination presents a facile way for fabricating size-controlled crystalline PDI assemblies with built-in electric field enhancing photoelectric and photocatalytic activities substantially.

Impact of Linker Groups on Self-Assembly, Gene Transfection, Antibacterial Activity, and In Vitro Cytotoxicity of Cationic Bolaamphiphiles

Cationic bolaamphiphiles have gained significant attention in various research fields, including materials science, drug delivery, and gene therapy, due to their unique properties and potential applications. The objective of the current research is to develop more effective cationic bolaamphiphiles. Thus, we have designed and synthesized two cationic bolaamphiphiles (-(CH2)12(2,3-dihydroxy-N,N-dimethyl-N-(3-ureidopropyl)propan-1-aminium chloride))2 (C12(DDUPPAC)2)) and (-(CH2)12(N-(3-(carbamoyloxy)propyl)-2,3-dihydroxy-N,N-dimethylpropan-1-aminium chloride)2 (C12(CPDDPAC)2) containing urea and urethane linkages, respectively. We have investigated their self-assembly properties in water using several techniques, including surface tension, electrical conductivity, fluorescence probe, calorimetry, dynamic light scattering, and atomic force microscopy. Their biological applications, e.g., in vitro gene transfection, antibacterial activity, and cytotoxicity, were studied. Both bolaamphiphiles were observed to produce aggregates larger than spherical micelles above a relatively low critical aggregation concentration (cac). The calorimetric experiments suggested the thermodynamically favorable spontaneous aggregation of both bolaforms in water. The results of interaction studies led to the conclusion that C12(CPDDPAC)2 binds DNA with a greater affinity than C12(DDUPPAC)2. Also, C12(CPDDPAC)2 is found to act as a more efficient gene transfection vector than C12(DDUPPAC)2 in 264.7 cell lines. The in vitro cytotoxicity assay using MTT, however, revealed that neither of the bolaamphiphiles was toxic, even at higher quantities. Additionally, both bolaforms show beneficial antibacterial activity.

Theranostic applications of peptide-based nanoformulations for growth factor defective cancers

Growth factors play a pivotal role in orchestrating cellular growth and division by binding to specific cell surface receptors. Dysregulation of growth factor production or activity can contribute to the uncontrolled cell proliferation observed in cancer. Peptide-based nanoformulations (PNFs) have emerged as promising therapeutic strategies for growth factor-deficient cancers. PNFs offer multifaceted capabilities including targeted delivery, imaging modalities, combination therapies, resistance modulation, and personalized medicine approaches. Nevertheless, several challenges remain, including limited specificity, stability, pharmacokinetics, tissue penetration, toxicity, and immunogenicity. To address these challenges and optimize PNFs for clinical translation, in-depth investigations are warranted. Future research should focus on elucidating the intricate interplay between peptides and nanoparticles, developing robust spectroscopic and computational methodologies, and establishing a comprehensive understanding of the structure-activity relationship governing peptide-nanoparticle interactions. Bridging these knowledge gaps will propel the translation of peptide-nanoparticle therapies from bench to bedside. While a few peptide-nanoparticle drugs have obtained FDA approval for cancer treatment, the integration of nanostructured platforms with peptide-based medications holds tremendous potential to expedite the implementation of innovative anticancer interventions. Therefore, growth factor-deficient cancers present both challenges and opportunities for targeted therapeutic interventions, with peptide-based nanoformulations positioned as a promising avenue. Nonetheless, concerted research and development endeavors are essential to optimize the specificity, stability, and safety profiles of PNFs, thereby advancing the field of peptide-based nanotherapeutics in the realm of oncology research.

Rh-coordinated histidyl bolaamphiphile assembly: a catalyst for the isomerization of cis-stilbene and cis-alkene

In this study, we present a colloidal assembly of histidyl bolaamphiphiles whose imidazoles coordinate with rhodium ions (HisC7[Rh]) to exhibit catalytic isomerization activity for cis-stilbene and cis-alkene molecules. The histidyl bolaamphiphiles self-assemble to form a soft scaffold that functions analogously to an apoenzyme. This scaffold exposes multiple histidyl imidazoles and carboxylates on its surface, to which rhodium ions bind, generating catalytically active sites. The Rh coordination with the biochemical functional groups was verified through comprehensive vibrational spectroscopy and calorimetry. The colloidal HisC7[Rh] demonstrated a significant catalytic effect on the isomerization of cis- to trans-stilbene under mild H2 conditions, resulting in 69% yield of trans-stilbene. In contrast, when Rh(cod)2BF4 was employed as a control catalyst, only the hydrogenated products of bibenzyl were obtained. These findings underscore the crucial role of histidyl motifs in exhibiting unique catalytic isomerization activity through the coordination with Rh. The catalytic activity of HisC7[Rh] is governed by several factors, such as rhodium content, solvent composition, temperature, and H2 pressure. Moreover, HisC7[Rh] displayed moderate isomerization activity towards not only stilbene but also unsaturated fatty acid isomers, highlighting its expansive potential as an isomerization catalyst.

Recent advances in self-assembling peptide matrices as functional coatings for implantable devices

Nature has evolved numerous supramolecular machineries for modulating various cellular functions. Inspired by the assembly of these sophisticated structures in nature, the controlled assembly of synthetic peptides emerges as a promising approach to therapeutically relevant applications. The self-assembling biomimetic peptides could form well-ordered architectures through non-covalent interactions such as π-π stacking, van der Waals, electrostatic, and hydrogen bonding. In addition, the peptidic building blocks are highly biocompatible and allow facile chemical manipulation with diverse functionalities. For decades, a serious of engineered self-assembling peptides have been extensively studied as functional hydrogels for various applications. Meanwhile, the surface modification strategies based on self-assembling peptide matrices have also raised the attention of biomaterials researchers due to their programmability and 3D porous morphologies. This concise review will cover recent advances in self-assembling peptide matrices as functional coatings for implantable devices. The opportunities and challenges in this field will also be discussed.