Silver
nanoparticles have been of great interest as plasmonic substrates
for sensing and imaging, catalysts, or antimicrobial systems. Their
physical properties are strongly dependent on parameters that remain
challenging to control such as size, chemical composition, and spatial
distribution. We report here on supramolecular assemblies of a novel
peptide amphiphile containing aldehyde functionality in order to reduce
silver ions and subsequently nucleate silver metal nanoparticles in
water. This system spontaneously generates monodisperse silver particles
at fairly regular distances along the length of the filamentous organic
assemblies. The metal–organic hybrid structures exhibited antimicrobial
activity and significantly less toxicity toward eukaryotic cells.
Metallized organic nanofibers of the type described here offer the
possibility to create hydrogels, which integrate the useful functions
of silver nanoparticles with controllable metallic content.
The use of cucurbit[8]uril as a molecular host has emerged in the chemical literature as a reliable strategy for the creation of dynamic chemical systems, owing to its ability to form homo- and heteroternary complexes in aqueous media with appropriate molecular switches as guests. In this manner, CB[8]-based supramolecular switches can be designed in a predictable and modular fashion, through the selection of appropriate guests able to condition the redox, photochemical, or pH-triggered behavior of tailored multicomponent systems. Furthermore, CB[8] allows the implementation of dual/triple and linear/orthogonal stimuli-dependent properties into these molecular devices by a careful selection of the guests. This versatility in their design gives these supramolecular switches great potential for the rational development of new materials, in which their function is not only determined by the custom-made stimuli-responsiveness, but also by the transient aggregation/disaggregation of homo- or heteromeric building blocks.
A surface-enhanced Raman scattering (SERS)-based sensor was developed for the detection of the oncoprotein c-Jun at nanomolar levels. c-Jun is a member of the bZIP (basic zipper) family of dimeric transcriptional activators, and its overexpression has been associated with carcinogenic mechanisms in several human cancers. For our sensing purpose, we exploited the ability of c-Jun to heterodimerize with its native protein partner, c-Fos, and therefore designed a c-Fos peptide receptor chemically modified to incorporate a thiophenol (TP) group at the N-terminal site. The TP functionality anchors the c-Fos protein onto the metal substrate and works as an effective SERS probe to sense the structural rearrangements associated with the c-Fos/c-Jun heterodimerization.
The use of fluorescent techniques in biological research is widespread. Many of the techniques rely on the use of fluorescent genetically-encoded tags (namely GFP and its different variants), but small molecules and nanoparticle-based approaches are being increasingly used. Peptides, owing to their modular nature, synthetic accessibility and biomolecular recognition potential, offer unique possibilities for the development of efficient and selective fluorescent sensors. In this tutorial review we present several of the strategies that have been used to develop fluorescent-based peptide sensors and discuss selected applications to biological problems.
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