Demetra Giuri

Amino acid-based surfactants are promising ingredients for cosmetic formulations, combining mildness with intrinsic self-assembly properties. A recent challenge in the cosmetic field is the replacement of synthetic polymers, used as rheological modifiers, with sustainable and biodegradable alternatives. In this work, sodium cocoyl glycinate (SCG) and sodium cocoyl alaninate (SCA) were investigated as both surfactants and supramolecular gelators for the development of a “supramolecular shampoo”. pK_a analysis and rheological studies revealed that SCG forms robust gel networks at pH 5, whereas SCA shows limited stability. The progressive incorporation of typical cosmetic ingredients, including cocamidopropyl betaine (CAPB), preservatives, conditioning agents, and fragrance, led to a controlled decrease in mechanical strength while preserving pseudoplastic behavior. The final formulation remained stable under accelerated aging and freeze–thaw conditions for months. These results demonstrate that supramolecular structuring offers a viable and sustainable alternative to conventional polymer-based systems in shampoo formulations.

We report the controlled synthesis of a new class of oxygen-bridged cyclo[2]malonates via condensation of malonyl dichloride with substituted benzylic α,ω-diols. Optimization of reaction conditions enables selective access to dimeric macrocycles, overcoming the intrinsic tendency toward higher oligomer formation. Single-crystal X-ray diffraction reveals well-defined conformations, tunable cavity sizes, and substituent-dependent stereochemical preferences. The macrocycles assemble into interlocked columnar architectures driven by shape complementarity and stabilized by C–H···O hydrogen bonding, with additional halogen bonding in iodinated derivatives. While α-proton acidity is retained across the series, vanadyl (VO²⁺) binding is strongly governed by cavity size and conformational preorganization, suggesting a structure–function relationship. These findings introduce cyclo[2]malonates as an accessible and versatile macrocyclic platform, combining structural tunability with predictable supramolecular behavior, and highlight their potential in molecular recognition and functional materials design.

Low-molecular-weight gelators (LMWGs) are small organic molecules that self-assemble through noncovalent interactions into fibrous networks capable of immobilizing solvents to create supramolecular gels that can be used in biomedical applications and other fields. Unlike robust polymeric gels, LMWGs offer tunability, stimuli-responsiveness, and easy degradation. Designing effective LMWGs requires a delicate balance of their weak, noncovalent interactions to form fibers instead of crystals. We investigated the critical molecular features required for the formation of a stimuli-responsive supramolecular gel derived from O-benzyl tyrosine. The amino moiety of the amino acid was coupled with six different fatty acids, yielding a series of compounds. Our screening revealed that Adi-[Tyr­(Bn)]₂ and Aze-[Tyr­(Bn)]₂ emerged as successful gelators, forming robust and responsive gels, while the other homologues formed less stable gels or precipitates, often yielding crystalline materials. The viscoelastic and self-assembly properties of the gels were comprehensively analyzed by rheology, electronic circular dichroism (ECD), and scanning electron microscopy (SEM), while single-crystal x-ray diffraction (SC-XRD) was used to confirm and elucidate their structural features. Interestingly, the ECD profile of Aze-[Tyr­(Bn)]₂ was reminiscent of collagen-mimetic assemblies, which are of interest for applications in tissue engineering and the design of biomaterials.

This paper reports on the use of acetyl-L-valine (Ac-Val) as an effective and precise pH modifier for inducing hydrogel formation. Ac-Val offers several advantages: it is fully water-soluble, overcoming dissolution issues, and allows for stock solution preparation to fine-tune trigger volume and final material pH. As a weaker carboxylic acid compared to inorganic acids, Ac-Val enables more controlled pH variation. For comparison, a commercial lactic acid (LA) solution was also evaluated. The reliability of Ac-Val as a pH modifier was tested on three amino acid derivatives—Boc-Dopa(Bn)₂-OH, Lau-Dopa(Bn)₂-OH, and Pal-Phe-OH, all known to be efficient gelators. These molecules, sharing common structural features, form gels varying in transparency, robustness, and elasticity. Notably, Pal-Phe-OH is a supergelator. A key benefit of Ac-Val lies in its ability to cause an instantaneous pH modification, allowing for precise pH adjustment before the gel network forms. This pH-change approach with Ac-Val demonstrates broad applicability, enabling the creation of gels with tailored pH values for various acidic molecules, which is particularly valuable for applications like drug delivery where specific pH environments are crucial.

This paper reports on the use of acetyl-L-valine (Ac-Val) as an effective and precise pH modifier for inducing hydrogel formation. Ac-Val offers several advantages: it is fully water-soluble, overcoming dissolution issues, and allows for stock solution preparation to fine-tune trigger volume and final material pH. As a weaker carboxylic acid compared to inorganic acids, Ac-Val enables more controlled pH variation. For comparison, a commercial lactic acid (LA) solution was also evaluated. The reliability of Ac-Val as a pH modifier was tested on three amino acid derivatives — Boc-Dopa(Bn)2-OH, Lau-Dopa(Bn)2-OH, and Pal-Phe-OH, all known to be efficient gelators. These molecules, sharing common structural features, form gels varying in transparency, robustness, and elasticity. Notably, Pal-Phe-OH is a supergelator. A key benefit of Ac-Val lies in its ability to cause an instantaneous pH modification, allowing for precise pH adjustment before the gel network forms. This pH-change approach with Ac-Val demonstrates broad applicability, enabling the creation of gels with tailored pH values for various acidic molecules, which is particularly valuable for applications like drug delivery where specific pH environments are crucial.

Cosmetic formulations are complex mixtures of ingredients that must fulfill several requirements. One of the challenges of the cosmetic industry is to find natural alternatives to replace synthetic polymers, preserving desirable sensory characteristics. The aim of this work is to induce the formation of gels, by replacing synthetic polymers with a low-molecular-weight gelator (LMWG), a small molecule able to self-assemble and form supramolecular networks. The impact of low-molecular-weight gelators on the environment is reduced as they are highly biodegradable. Thus, the behavior of solutions containing Boc-L-Dopa(Bn)₂-OH, an LMWG, together with ten different anionic surfactants, was studied to understand if the LMWG may act as a rheological modifier by increasing the viscosity of the formulation or forming gels with these ingredients. An amphoteric surfactant, cocamidopropyl betaine (CAPB), often used to increase cleansing gentleness, was also added to the solutions to better mimic a cosmetic formulation. In most cases, the addition of the gelator at only a 1% w/v concentration induces the gelification or an increase in the viscosity of the solutions, thus showing that this molecule is also able to self-assemble in complex mixtures.

Cosmetic formulations are complex mixtures of ingredients that must fulfil several requirements. One of the challenges of the cosmetic industries is to find natural alter-natives to replace synthetic polymers, preserving desirable sensory characteristics. The aim of this work is to induce the formation of gels, by replacing synthetic polymers with a low-molecular-weight gelator (LMWG), a small molecule able to self-assemble and to form supramolecular networks. The impact on environment of low-molecular-weight gelators is much reduced, as they are highly biodegradable. Thus the behaviour of so-lutions containing Boc-L-Dopa(Bn)2-OH, a LMWG, together with ten different anionic surfactants was studied, to understand if the LMWG may act as rheological modifier by increasing the viscosity of the formulation or forming gels with these ingredients. In most cases, the addition of the gelator in only 1% w/v concentration induces the gelifi-cation of the solutions, thus showing that this molecule is able to self-assemble also in complex mixture. An amphoteric surfactant, cocamidopropyl betaine (CABP), often used to increase cleansing gentleness, was also added to the solutions to better mimic a cosmetic formulation. These samples form gels, thus showing that the CABP addition does not disturb their formation.

Low‐molecular‐weight (LMW) gelators are a versatile class of compounds able to self‐assemble and to form supramolecular materials, such as gels. The use of LMW peptides to produce these gels shows many advantages, because of their wide structure tunability, the low‐cost and effective synthesis, and the in vivo biocompatibility and biodegradability, which makes them optimal candidates for release and delivery applications. In addition, in these materials, the binding of the hosts may occur through a variety of noncovalent interactions, which are also the main factors responsible for the self‐assembly of the gelators, and through specific interactions with the fibers or the pores of the gel matrix. This review aims to report LMW gels based on amino acid and peptide derivatives used for the release of many different species (drugs, fragrances, dyes, proteins, and cells) with a focus on the possible strategies to incorporate the cargo in these materials, and to demonstrate how versatile these self‐assembled materials are in several applications.