Tripeptide Self-Assembly into Bioactive Hydrogels: Effects of Terminus Modification on Biocatalysis

Bioactive hydrogels based on the self-assembly of tripeptides have attracted great interest in recent years. In particular, the search is active for sequences that are able to mimic enzymes when they are self-organized in a nanostructured hydrogel, so as to provide a smart catalytic (bio)material whose activity can be switched on/off with assembly/disassembly. Within the diverse enzymes that have been targeted for mimicry, hydrolases find wide application in biomaterials, ranging from their use to convert prodrugs into active compounds to their ability to work in reverse and catalyze a plethora of reactions. We recently reported the minimalistic l-His-d-Phe-d-Phe for its ability to self-organize into thermoreversible and biocatalytic hydrogels for esterase mimicry. In this work, we analyze the effects of terminus modifications that mimic the inclusion of the tripeptide in a longer sequence. Therefore, three analogues, i.e., N-acetylated, C-amidated, or both, were synthesized, purified, characterized by several techniques, and probed for self-assembly, hydrogelation, and esterase-like biocatalysis. This work provides useful insights into how chemical modifications at the termini affect self-assembly into biocatalytic hydrogels, and these data may become useful for the future design of supramolecular catalysts for enhanced performance

Sustainable Thermosetting Polyurethane Resins as interlayers and primary Encapsulants in emerging photovoltaics

International audienceNowadays, polyurethane-based materials are massively exploited in a plethora of applications, from adhesives to foams, from building insulations to athletic tracks. Recently, the specifical use of aliphatic thermosetting polyurethanes (aPUs) has enormously increased in the industrial context for their versatile synthesis and tunable physicochemical properties. In the context of photovoltaics, and more specifically, the emerging field of Perovskite Solar Cells (PSCs), we proposed the use of thermosetting polyurethanes as low-cost but effective encapsulants on rigid devices. [1]The advantage of thermosetting PUs over other polymeric encapsulants lies in their tunable flexibility. Indeed, a properly designed combination of precursors leads to a PU that could be coupled with PET in flexible PSCs, allowing PU-protected devices to outperform the non-encapsulated cells in both conventional and high-humidity (RH > 70%) environments. Another possibility with thermosetting PU is their application as both encapsulant and interlayer in tandem devices; more in detail, we exploited a specifically designed formulation (i.e., having a refractive index comparable to the one of glass and a transmittance higher than 90%) to glue together a NIR-Dye Sensitized Solar Cell and a UV-absorbing PSC. The final tandem device reached a total efficiency close to 10% with an Average Visible Transmittance (AVT) as high as 35%, leading to a Light Utilization Efficiency close to 3.5%. All the proposed formulations have been engineered to improve their sustainability by replacing fossil fuel precursors with bio-based or waste-derived ones [2], thus leading to high-performing but sustainable encapsulants and interlayers for emerging photovoltaics