2024
Microfluidic-driven short peptide hydrogels with optical waveguiding properties.
A. M. Garcia, J. A. Garcia-Romero, S. H. Mejías, P. Prieto, V. Saggiomo, A. H. Velders, M. L. Soriano, V. Ruiz-Díez, J. Cabanillas-González, M. V. Gomez.
J. Mat. Chem. C. 2024, 12, 6027-6034.
Soft photonic elements with optical waveguiding ability based on biocompatible hydrogels have become increasingly important in optical techniques for medical diagnosis and phototherapy, among others. Supramolecular hydrogels based on peptides with interesting optical properties are rarely reported and explored. Although robust crystals based on short peptides have shown optical waveguiding capabilities, their rigidity is the main issue to overcome in the quest for soft biocompatible materals. Here, we report on the microfluidic-assisted formation of a heterochiral short peptide hydrogel that exhibits active optical waveguiding properties thanks to the incorporation of two different dyes, thioflavin T and rhodamine B, into the hydrogel structure. Using our microfluidic platform, different parameters such as the concentration of a peptide, type of dye and its concentration, and flow rate have been rapidly explored, with remarkable low reagent consumption. In this way, it was possible to develop peptide hydrogel waveguides with good optical loss values, modulating the emission in diverse spectral regions. The use of microfluidics to prepare these hydrogels makes possible the preparation of structures of high length-to-diameter aspect ratios, which otherwise are hard to devise from bulk conditions. Overall, this work broadens the use of supramolecular self-assembly of peptides to create functional materials with additional versatility to polymeric hydrogels, thanks to the possibility of tuning the structure by changing amino acid sequences. Additionally, the optical properties can be easily modulated by quick optimization of experimental parameters via microfluidic technology.
DOI: 10.1039/D4TC00282B
Self-assembled D–π–A multifunctional systems with tunable stimuli-responsive emission and optical waveguiding behaviour
R. Martín, A. Sanchez-Oliva, A. Benito, I. Torres-Moya, A. M. Garcia, J. Álvarez-Conde, J. Cabanillas-González, P. Prieto, B. Gómez-Lor.
J. Mat. Chem. C. 2024, 12, 2903-2910.
Smart materials with stimuli-responsiveness are a subject of great attention nowadays. In this work, we describe two D–π–A naphthalenimide (NI) derivatives, with different N-functionalization prepared by an environmentally benign process. They self-assemble into fluorescent crystals that display optical waveguiding behaviour with low optical loss coefficients. In addition, they present thermal/mechanical stimuli-responsiveness, which is tuned upon substitution at the molecular main core as a result of changes in crystal packing. A cold-crystallization process, as confirmed by DSC and power X-ray analysis, was identified as the underlying cause of the colour change upon heating, which can be reverted due to an amorphization process upon shearing. The combination of the reversible coloured amorphous-crystalline phase transition, together with the light guiding, holds significant promise for practical applications including use in security inks, rewritable materials or modern optics.
DOI: 10.1039/d3tc04100j
Metal ions trigger the gelation of cysteine-containing peptide-appended coordination cages.
M. Li, H. Zhu, S. Adorinni, W. Xue, A. Heard, A. M. Garcia, S. Kralj, J. R. Nitschke, S. Marchesan.
Angew. Chem. Int. Ed. 2024, e202406909.
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.
DOI: 10.1002/anie.202406909
Insulin amyloid fibril formation reduction by tripeptide stereoisomers.
B. Rosetti, S. Kralj, E. Scarel, S. Adorinni, B. Rossi, A. V. Vargiu, A. M. Garcia, S. Marchesan.
Nanoscale 2024, 16, 11081-11089
Insulin fibrillation is a problem for diabetic patients that can occur during storage and transport, as well as at the subcutaneous injection site, with loss of bioactivity, inflammation, and various adverse effects. Tripeptides are ideal additives to stabilise insulin formulations, thanks to their low cost of production and inherent cytocompatibility. In this work, we analysed the ability of eight tripeptide stereoisomers to inhibit the fibrillation of human insulin in vitro. The sequences contain proline as β-breaker and Phe–Phe as binding motif for the amyloid-prone aromatic triplet found in insulin. Experimental data based on spectroscopy, fluorescence, microscopy, and calorimetric techniques reveal that one stereoisomer is a more effective inhibitor than the others, and cell live/dead assays confirmed its high cytocompatibility. Importantly, in silico data revealed the key regions of insulin engaged in the interaction with this tripeptide, rationalising the molecular mechanism behind insulin fibril formation reduction.
DOI: 10.1039/d4nr00693c
Effect of Meso- or b-Functionalization of Porphyrins on the Photovoltaic Properties of Organic Solar Cells
R. Caballero, R. Dominguez, S. Shankar S., M. Privado, P. Prieto, P. de la Cruz, R. Singhal, G. D. Sharma, F. Langa.
RRL Solar, 2024, 2400069
Porphyrin derivatives are widely used as donors in organic solar cells (OSCs) due to their excellent optical and electrochemical properties. Although porphyrins can be functionalized at the meso- and β-positions, only meso-functionalized porphyrins have been reported as OSCs. Consequently, a direct comparison of the properties of porphyrins functionalized at these two positions is needed. The synthesis of two similar D–π–A–π–D materials is described herein and these compounds contain benzothiadiazole as the acceptor core and two Ni-porphyrins as donors functionalized at the meso- and β-positions to give RC19 and RC20, respectively. The optical and electrochemical properties of these compounds are reported. All-small-molecule OSCs based on RC19:TOCR1 and RC20:TOCR1 active layers show power conversion efficiencies (PCEs) of 13.72% and 5.20%, respectively. It should be noted that the PCE of 13.72% obtained for RC19:TOCR1 devices is, to one's knowledge, the highest value reported for porphyrin-based binary OSCs. The higher PCE obtained for RC19 is due to its higher photon harvesting ability, more efficient exciton dissociation and charge transfer, balanced charge transport, and lower bimolecular and trap-assisted recombination.
DOI: 10.1002/solr.202400069