1,720,969 research outputs found
Gold Nanoparticles Guided by Self‐Assembling Peptides: From Sequence to Superstructure
No full textPeptide-based supramolecular assemblies have emerged as useful scaffolds to control the synthesis and spatial organization of gold nanoparticles (AuNPs) into nanocomposite superstructures. This concept article summarizes recent progress in the design of peptide-directed AuNP assemblies, focusing on how subtle variations in peptide sequence, conjugation strategy, and synthesis conditions influence NP morphology, chiral arrangement, and the resulting optical properties. It highlights key strategies for rationally tailoring structural parameters, such as particle size, shape, and interparticle spacing, which determine the collective optical and plasmonic behaviors of the assemblies. The fundamental design rules discussed here provide critical insights for constructing programmable AuNP-based nanomaterials, potentially useful in diverse fields including sensing, optical devices, and catalysis. Finally, it outlines current challenges and propose directions to further exploit the unique versatility of peptide-nanoparticle hybrid systems in nanotechnology
Combined Supra- & Nano-Architectures for Functional Materials
No full textL’enorme sviluppo tecnologico degli ultimi anni ha guidato la ricerca verso strade alternative per la produzione di materiali a basso costo e con proprietà sempre migliori. Questi nuovi materiali con diverse potenziali applicazioni sono comunemente denominati materiali funzionali. In particolare, questi materiali smart sono in grado di cambiare le loro proprietà in risposta a diversi stimoli (ad esempio chimici, fisici o meccanici). In letteratura è riportata una grande varietà di questi materiali, come i materiali carboniosi, i materiali “soft” (ad esempio gel, cristalli liquidi, liquidi ionici), o in generale materiali supramoleculari. La possibilità di regolare in modo fine le loro proprietà, grazie alla combinazione di diversi materiali, è estremamente attrattiva. Questo approccio può portare a nuove materiali compositi o ibridi, con nuove proprietà in modo da estendere la gamma delle diverse possibili applicazioni.
In questo progetto di dottorato si sono sintetizzati diversi materiali funzionali a base di gel di peptidi supramolecolari o nanotubi di carbonio (CNTs), combinati con delle gabbie supramoleculari (MOCs). Nel Capitolo 2, in particolare, viene descritta la sintesi di nuove gabbie aventi dei peptidi come leganti periferici. I peptidi scelti per questo scopo sono tripeptidi eterochirali PABA-L-Phe-D-Xaa-L-Phe-NH2 (Xaa = Ala, Val, Leu, Ile) derivatizzati al N-terminale con un gruppo p-amino benzoico e amidati al C-terminale. Tutti i peptidi sono in grado di assemblare in acetonitrile a diverse concentrazioni. L’assemblaggio dei peptidi, con diverse aldeidi e ioni metallici ha portato alla formazione di diverse gabbie supramoleculari. L’abilità di formare gel delle gabbie è stata studiata e razionalizzata sia da un punto di vista teorico (Dinamica Molecolare) e sperimentale (Spettroscopia UV Raman Risonante). Il Capitolo 3 si focalizza sullo studio dell’auto-assemblaggio di gabbie simili a quelle del precedente capitolo, ma il cui auto-assemblaggio si basa un altro tipo di interazione. I peptidi utilizzati contengono degli atomi di zolfo sulle catene alterali degli amino acidi. La capacità delle gabbie di gelare è indotta dalla formazione di un legame di coordinazione tra lo zolfo e altri ioni metallici (Ag+, Zn2+, Hg2+), aggiunti in soluzione. La capacità di formare gel in presenza di metalli pesanti può essere estremamente promettente per la rimozione di metalli tossici dall’ambiente.
Nel Capitolo 4 viene riportato il primo esempio di funzionalizzazione di CNTs con le MOCs. Si è inizialmente studiata l’affinità delle MOC verso diverse tipologie di CNTs mediante analisi termogravimetrica. La gabbia utilizzata nello studio ha inoltre la capacità di passare da un solvente acquoso ad uno organico grazie al cambio di contro ione. Questa abilità è stata utilizzata per testare la separazione di CNTs con diversi diametri mediante estrazione di fase. Ulteriori sviluppi in quest’area potrebbero portare ad enormi avanzamenti nel campo della separazione, della sensoristica e della catalisi.The technological advances over the last years are driving research towards alternative ways to produce materials with reduced cost and enhanced properties. These newly synthesised materials with various potential applications are referred to as functional materials. In particular, smart materials change their properties in response to a certain stimulus (e.g., chemical, physical or mechanical), thus enabling new potential applications. In literature, there is a wide variety of functional materials, such as carbon nanomaterials, soft materials (i.e. gels, liquid crystals, ionic liquids), and, generally, supramolecular materials. The possibility of fine-tuning the properties of different materials by combing them together is very attractive. This approach can lead to novel composites or even hybrids, which display new properties, thus extending the range of possible applications.
This Ph.D. thesis focuses on the synthesis of innovative functional materials based on supramolecular peptide gels or carbon nanotubes (CNTs) combined with metal organic cages (MOCs). In particular, Chapter 2 describes the synthesis on new MOCs having pendant peptides as peripherical ligands. The peptides chosen for this purpose were heterochiral tripeptides PABA-L-Phe-D-Xaa-L-Phe-NH2 (Xaa = Ala, Val, Leu, Ile) derivatised at the N-terminus with a p-amino benzoyl unit and amidated at the C-terminus. All four peptides were able to gel on their own. The peptides were self-assembled with different aldehydes and metal ions to obtain different MOCs. The gelling ability of the MOCs was studied and it was rationalized both from a theoretical (Molecular Dynamics) and experimental point of view (UV Resonance Raman Spectroscopy).
Chapter 3 investigates the self-assembly of MOCs containing pendant peptides based on another type of interaction. In this case the tripeptides contain sulfur on their sidechains. The gelation of these MOCs was induced by the formation of coordinative bond between the sulfur unit and other metals ions (i.e., Ag+, Zn2+, Hg2+). This gelation in the presence of heavy metals holds promise for the removal of toxic metal ions from the environment.
Chapter 4 describes the first example of functionalisation of CNTs with MOCs. The affinity of the MOC for different CNT types was studied through thermogravimetric analysis (TGA). The MOC employed in this study was able to transfer between aqueous and organic solvents by counter-anion exchange. The MOC binding onto the CNTs enabled their phase transfer as well, upon ion exchange. This phenomenon was exploited to test CNT sorting by phase extraction depending on their diameter.
In conclusion, this work identified new ways to combine supramolecular materials with nanostructures, offering new designs to hierarchically co-assemble tripeptides, aldehydes, and metal ions into gelling MOCs, as well as providing the first example of MOC binding onto CNTs to transfer them across phases for sorting. Further developments in these areas could enable advances in separation, sensing or catalysis
Smart Hydrogels Meet Carbon Nanomaterials for New Frontiers in Medicine
Full text linkCarbon nanomaterials include diverse structures and morphologies, such as fullerenes, nano-onions, nanodots, nanodiamonds, nanohorns, nanotubes, and graphene-based materials. They have attracted great interest in medicine for their high innovative potential, owing to their unique electronic and mechanical properties. In this review, we describe the most recent advancements in their inclusion in hydrogels to yield smart systems that can respond to a variety of stimuli. In particular, we focus on graphene and carbon nanotubes, for applications that span from sensing and wearable electronics to drug delivery and tissue engineering
Metal Ions Trigger the Gelation of Cysteine‐Containing Peptide‐Appended Coordination Cages
Full text link: We report a series of coordination cages that incorporate peptide chains at their vertices, prepared through subcomponent self-assembly. Three distinct heterochiral tripeptide subcomponents were incorporated, each exhibiting an L-D-L stereoconfiguration. Through this approach, we prepared and characterized three tetrahedral metal-peptide cages that incorporate thiol and methylthio groups. The gelation of these cages was probed through the binding of additional metal ions, with the metal-peptide cages acting as junctions, owing to the presence of sulfur atoms on the peripheral peptides. Gels were obtained with cages bearing cysteine at the C-terminus. Our strategy for developing functional metal-coordinated supramolecular gels with a modular design may result in the development of materials useful for chemical separations or drug delivery
Green Approaches to Carbon Nanostructure-Based Biomaterials
Full text linkThe family of carbon nanostructures comprises several members, such as fullerenes, nano-onions, nanodots, nanodiamonds, nanohorns, nanotubes, and graphene-based materials. Their unique electronic properties have attracted great interest for their highly innovative potential in nanomedicine. However, their hydrophobic nature often requires organic solvents for their dispersibility and processing. In this review, we describe the green approaches that have been developed to produce and functionalize carbon nanomaterials for biomedical applications, with a special focus on the very latest reports
Self‐assembling tripeptide forming water‐bound channels and hydrogels
Full text linkD-Ser(tBu)-L-Phe-L-Trp is described as a self-assembling tripeptide that yields nanofibrillar hydrogels at physiological conditions (phosphate buffer at pH 7.4). The peptide is characterized by several spectroscopic methods, such as circular dichroism and fluorescence, oscillatory rheometry, and transmission electron microscopy. Single-crystal X-ray diffraction reveals supramolecular packing into water-bound channels and allows the visualization of the intermolecular interactions holding together peptide stacks
Self-Assembly and Gelation Study of Dipeptide Isomers with Norvaline and Phenylalanine
Full text linkDipeptides have emerged as attractive building blocks for supramolecular materials thanks to their low-cost, inherent biocompatibility, ease of preparation, and environmental friendliness as they do not persist in the environment. In particular, hydrophobic amino acids are ideal candidates for self-assembly in polar and green solvents, as a certain level of hydrophobicity is required to favor their aggregation and reduce the peptide solubility. In this work, we analyzed the ability to self-assemble and the gel of dipeptides based on the amino acids norvaline (Nva) and phenylalanine (Phe), studying all their combinations and not yielding to enantiomers, which display the same physicochemical properties, and hence the same self-assembly behavior in achiral environments as those studied herein. A single-crystal X-ray diffraction of all the compounds revealed fine details over their molecular packing and non-covalent interactions
Racemic peptide assembly boosts biocatalysis
No full textRacemic assembly of minimalistic heterochiral tripeptides boosts their biocatalytic activity for ester hydrolysis. The amino acidic sequences are bioinspired and feature histidine (His) as a catalytically active residue, and the diphenylalanine (Phe-Phe) motif to drive self-assembly into anisotropic nanostructures that gel. This study thus provides key insights for the design of green biocatalysts with improved activity
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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