IMDEA Nanoscience

Van der Waals (vdW) materials provide a platform to study and control the physical properties of low-dimensional materials. While strategies developed for 2D crystals are not directly transferable to 1D systems, we can benefit from them by creating layers formed by interconnected chains. Here, we develop a molecular strategy to illustrate this concept consisting of assembling 1D materials in 2D metal-organic frameworks (MOFs). Crystals of [FeX(pzX)(bpy)] (X = Cl, F; pz = pyrazole; bpy = bipyridine) consist of iron chains along the b-axis, crosslinked via bpy ligands along the a-axis to form 2D layers, stacked along the c-axis via vdW forces. This structural anisotropy manifests itself in highly-anisotropic optical properties, as demonstrated by optical measurements in the visible and terahertz ranges, results which are supported by DFT calculations. Chemical substitution enables the tuning of the optical properties, as exemplified by the photoluminescence of the Cl-derivative, which is quenched for the F-derivative. Thin-layers are obtained by mechanical exfoliation, and their optical properties are further tuned through the fabrication of orthogonally-twisted vdW heterostructures, enabling to effectively switch-off the optical anisotropy. Our work highlights the chemical flexibility of vdW layered MOFs as a platform for designing and manipulating 1D architectures.

Corrole photosensitizers for photodynamic therapy (PDT) have garnered significant attention due to their promising potential in cancer treatment. Advances in understanding their photophysical and photochemical properties have facilitated the development of more efficient and targeted PDT strategies. This study reports the synthesis and characterization of a series of alkyne-substituted gallium(iii) corrole complexes, as well as their conjugation to azide-functionalized glycofullerenes via copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions. The resulting glycofullerene-corrole conjugates were obtained and fully characterized using standard spectroscopic techniques. Their photodynamic efficacy was evaluated in vitro using HeLa cells. Among the series, the mono- and tris-alkyne-substituted corroles, as well as the monofunctionalized glycofullerene conjugate, exhibited the most potent PDT effects in cells, achieving IC50 values below 1.0 µM under blue irradiation at 420 nm with a total light dose as low as 5 J cm-2. These findings highlight the potential of gallium(iii) corrole-based nanostructures as water-soluble and efficient photosensitizers for PDT applications.

The combination of 2D materials and metallic nanoparticles (NPs) enables the creation of hybrid systems with enhanced properties, such as improved light absorption via plasmon resonance or the introduction of active catalytic sites. However, effectively interfacing 2D materials with NPs remains challenging. This work presents a novel and efficient à la carte synthesis approach that enables the tailored chemical linkage of noble metal NPs-gold (Au), platinum (Pt), and palladium (Pd)- to ultrathin 2H-MoS2 sheets using orthogonal maleimide-based linkers. Specifically, alkyne-, carboxylic acid-, and phenyl bromide-terminated maleimides are employed to anchor Au, Pt, and Pd NPs, respectively. This modular strategy allows precise control over the surface chemistry, leading to uniform decoration with sub-2nm NPs and robust attachment to the MoS2 substrate. This chemical linkage is expected to enhance the interaction between the MoS2 and the NPs while also improving the mechanical stability of the hybrid material. These combined effects make the system particularly promising for applications requiring both strong interfacial coupling and durability, such as electrocatalysis, sensing, and flexible electronic devices.

Two-dimensional (2D) van der Waals (vdW) antiferromagnets (AFMs) have emerged as promising candidates for spintronic applications due to their fast spin dynamics and robustness against external magnetic perturbations. However, their intrinsically low electrical conductivity challenges their integration into electronic devices. A possible path to overcome this limitation is to form vdW heterostructures with highly conductive materials such as graphene, which can sensitively respond to interfacial magnetic interactions. Such an interplay is, however, far from being understood. In this work, we investigate vdW heterostructures composed of single-layer graphene and the antiferromagnet FePS3 (FEPS). Electron transport measurements in a field-effect transistor geometry reveal a sharp change in graphene resistance precisely at the Néel temperature of FEPS. Temperature-dependent Raman spectroscopy and gate-dependent transport suggest a distinct interfacial charge transfer driven by the antiferromagnetic ordering. Density functional theory (DFT) calculations support this mechanism, showing a significant modulation of charge transfer across the interface linked to the magnetic phase. These findings unveil a strong interplay between magnetism and electron transport in 2D vdW heterostructures and pave the way toward integrating antiferromagnetic vdW materials into future electronic and spintronic technologies.

Abstract Photodynamic therapy (PDT) is a clinically approved anticancer treatment based on the generation of reactive oxygen species (ROS) when a photosensitizing agent (PS) is irradiated with specific light. Typically, irradiation is performed to cover the entire tumor or treatment area. However, this approach presents some disadvantages, including irradiation of the surrounding normal tissue. Therefore, this study introduces a novel phototherapeutic approach using single‐point laser irradiation. With the plasma membrane as the primary organelle target, it is demonstrated that single‐point laser irradiation induces plasma membrane damage in cancer cells using two clinically approved fluorescent markers for Glioblastoma: Protoporphyrin IX (PPIX), which localizes to the plasma membrane, and Sodium Fluorescein (NaF), which remains in the extracellular space, contacting the membrane. Single‐point laser irradiation in photodynamic therapy induces plasma membrane disruption in both cases, resulting in selective necrotic cancer cell death. Interestingly, this approach induces cell death from within the spheroids, and the cell death gradually extends to the rest of the spheroid, minimizing damage to the surrounding tissue. In conclusion, this study presents a novel approach using focused laser irradiation and clinically approved dyes to induce precise, targeted cell death within the tumor, suggesting potential for theranostic applications in tumor eradication.

Despite intensive research in tip‐enhanced Raman spectroscopy (TERS), the angular distribution of Raman scattering in the TERS gap remains experimentally unreported leaving its relevance to the TERS signal formation to be seldomly discussed. Here, we investigate the angular distribution of the tip‐enhanced Raman signal in the Fourier plane using a model system composed of flat‐lying cobalt (II) hexadecafluoro‐phthalocyanine (CoPcF16) molecules physically adsorbed on a smooth gold surface. Both in‐plane and out‐of‐plane vibrational modes are observed, where the out‐of‐plane Raman modes at about 678 and 740 cm−1 have different angular intensity distributions than those of in‐plane Raman modes at 1309 and 1373 cm−1. We interpret the angular spectrum of the TERS signal considering the molecular vibrational modes computed with density functional theory (DFT) for the free and gold‐deposited molecule, and the directed Raman scattering by the gap‐mode predicted by finite‐difference time‐domain (FDTD) simulations. We contend that the TERS gap directs the Raman vibrational modes differently, leading to distinct angularly distributed Raman scattering intensities. These findings emphasize the nonnegligible role of the TERS detection scheme in understanding spectral features, such as the relative peak intensity ratio variations for studying molecular orientations, or for monitoring chemical reactions.

An ideal implant surface should promote cell attachment and tissue integration while preventing bacterial colonization. Engineering the surface topography of a biomaterial implant to elicit a differential response is a promising approach to dealing with both issues. To achieve this, we integrated Moth-Eye (ME) nanocones with micrometric features such as gratings and pillars in various hierarchical configurations, leading to different responses in bacteria and cells. These hierarchical topographies were tested on different polymers to compare their biological responses. Mesenchymal stem cells (MSCs) were employed as a model system to study cell behavior, given their ability to proliferate, self-renew, and differentiate. The bactericidal effect was tested using gram-negative Escherichia coli and gram-positive Staphylococcus aureus. Results show that these topographies-maintained cell viability and influenced cell morphology, orientation, migration and differentiation, which are crucial processes for regeneration and osseointegration. Finite Element Method (FEM) simulations estimated the traction forces generated by cells on these surfaces. Overall, the hierarchical topographies enhanced the expression of osteogenic markers in the MSCs while retaining the bactericidal properties of the ME nanostructures.

On-surface chemistry represents a fast-growing field that allows to synthesize molecular structures not available by traditional wet chemistry. In this context, high-resolution scanning probe microscopy techniques can provide an unprecedented spatial resolution, allowing to precisely identify individual products of the reactions. Nevertheless, a deep understanding of the reaction mechanism under the conditions imposed by the substrate remains unknown.In this context, various computational strategies are available to characterize the optimal reaction pathways of the chemical processes that take place on the surfaces of solids. For example, the nudged elastic band (NEB) is one of the most popular approaches, as well as different transition state theory methods beyond it. These approaches had demonstrated their capability to characterize the potential energy landscape of the reaction pathways [1-2]. Another approach that attracts the interest of the on-surface synthesis community is the application of molecular dynamics (MD) methods, within the canonical ensemble, and based on the QM/MM (quantum mechanics/molecular mechanics) of the interatomic forces [3-4]. This approach, that combines Density functional theory (DFT) and empirical force fields to describe the interaction forces, allows to simulate very large systems, at a very low computational cost while still accounting for the crucial quantum mechanics interactions. Also, such temperature-dependent simulations include the effect of entropy, vibrations modes, concerted motion, etc.I will present the experimental and computational results of different projects in which we are making use of these computational approaches to achieve a better understanding of the on-surface synthesis experiments performed by the group. For example, the rationalization of the transformation of a benzodithiophene precursor deposited on a Ag(111) substrate (See Figure 1a). The group had also studied the stepwise transformation of coronene-based organometallic networks into two-dimensional covalent patches through intermolecular homocoupling (See Figure 1b). We had as well investigated the transformation of indenyl precursors, through a triple C-H cleavage followed by a peripheral directed homocoupling, to form a polyacetylene backboned polymer that features a parity dependent and highly delocalized soliton in-gap state (See Figure 1c). [5]

The design of bottom-up synthesis of molecular nanographenes (NGs) has typically been explored through the preparation of functionalized hexa-peri-hexabenzocoronene (HBC) derivatives.[1] This synthetic approach usually involves a [4+2] Diels-Alder reaction followed by a graphitization process using the Scholl reaction, which can often be challenging.[2] In this work, we propose a simplified approach for the preparation of molecular NGs through a single-step condensation reaction. This method allows for the construction of increasingly complex structures with the tailored design of a nanographene fragment (referred to as 1 in Figure 1). Using this approach, we have developed a family of aza-nanographenes that incorporate either planar scaffolds (benzene and triphenylene) or 3D platforms such as cyclooctatetraene (COT).[3] The newly synthesized aza-nanographenes exhibit remarkable optical properties, including high fluorescence quantum yield (QY) and emissive processes such as aggregation-induced emission (AIE) (Figure 1, right). AIE is an emerging optical property in molecular NGs, with significant potential across various fields, including chemistry, materials science, and biomedical applications. To date, only a few molecular nanographenes displaying AIE properties have been described in the literature,[4] making this family of compounds excellent candidates for developing applied optoelectronic applications. Furthermore, this work includes a comprehensive density functional theory (DFT) study of the different photophysical processes observed in the aza-NGs, providing theoretical support for the experimental data.

La sentencia sobre el asunto T-375/22 del Tribunal General de la Unión Europea representa un hito en la delimitación jurisprudencial del conflicto entre el derecho de acceso a los documentos institucionales y la protección de los datos personales en el ámbito parlamentario. Este trabajo examina críticamente los fundamentos jurídicos y las implicaciones estructurales de dicho fallo, prestando especial atención al modo en que se aplican las excepciones previstas en el Reglamento 1049/2001 cuando los documentos solicitados contienen información sobre eurodiputados y sus asistentes. A partir del análisis del rol del consentimiento, el interés público y el principio de proporcionalidad, se concluye que la sentencia refuerza una interpre­tación restrictiva del derecho de acceso, sin diferenciar entre sujetos con distinta exposición pública. Asimismo, se argumenta que el fallo consolida una arquitectura institucional donde el Parlamento Europeo conserva un margen discrecional excesivo para limitar la transparencia, debilitando tanto el acceso pasivo como la adopción de prácticas de transparencia activa. Todo ello plantea desafíos relevantes para el modelo de control democrático y de rendición de cuentas en el seno de la Unión Europea.