Cada año, un comité de expertos debe acometer una ardua tarea: de entre todas las publicaciones de ICREA, debe escoger unas cuantas que destaquen del resto. Es todo un reto: a veces los debates se acaloran, y siempre son difíciles, pero acaba saliendo una lista con las mejors publicaciones del año. No se concede ningún premio, y el único reconocimiento adicional es el honor de ser resaltado en la web de ICREA. Cada publicación tiene algo especial, ya sea una solución especialmente elegante, un éxito espectacular en los medios de comunicación o la simple fascinación por una idea del todo nueva. Independientemente de la razón, se trata de los mejores de los mejores y, como tales, nos complace compartirlos aquí.


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  • White paper on astrocytes in diseases of the central nervous system (2021)

    Galea, Elena (UAB)

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    White paper on astrocytes in diseases of the central nervous system

    Astrocytes are a type of cell in the central nervous system (CNS) with homeostatic and computational roles in neural circuits. Hypertrophy of astrocytes was recognized in the mid XIXth century as an almost universal sign of CNS pathology, and the term ‘reactive astrocytes’ was coined to describe astrocytic remodeling in response to pathologic conditions. In the decade of the 90s of the XXth century, the study of reactive astrocytes exploded as part of the so-called ‘neuroinflammation’ in CNS pathologies; however, thirty years later the field is stagnated. There are no therapies derived from research on ‘inflammatory’ astrocytes, data from highly influential studies cannot be reproduced, and, importantly, astrocyte experts do not agree on basic issues including what reactive astrocytes are. A few of us capitalized on this discontent by fostering a necessary debate. The result is a working consensus of 80+ authors on reactive astrocytes. We take positions on controversies regarding the impact of astrocytes in CNS diseases, we discuss nomenclature, provide definitions, and we outline a systematic approach to unraveling the contribution of astrocytes to disorders of the CNS aging. This article is expected to inform clinical thinking and research on astrocytes and to promote the development of astrocyte-based biomarkers and therapies.

  • Complete coupling of light to optical surface excitations (2021)

    García de Abajo, Francisco Javier (ICFO)

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    Complete coupling of light to optical surface excitations

    Confining optical modes well below the size determined by the light wavelength at the same frequency is beneficial for the design of compact and efficient optical devices because light concentration impacts the electromagnetic energy density, the ability of light to interact with analytes in sensors, and the nonlinear response of materials in all-optical light modulators. However, such confinement comes at the prize that coupling of propagating light to those modes is made more inefficient because of the mismatch with the light wavelength. Light coupling in and out of confined modes is in fact a major pending problem that limits the practical applicability of the optical confinement strategy in nanophotonics.

    Small scatterers are commonly employed to assist light coupling because they allow targeting designated spatial regions in space, matching the area occupied by the confined modes. However, when those scatterers are placed close to the materials supporting the optical modes, the coupling is reduced by losses introduced through the coupling itself, acting as a loss channel. In this work, we have proposed the use of small scatterers placed at a suitable distance from a surface supporting optical modes as a strategy to realize complete optical coupling into such optical modes. By employing lossless, resonant scatterers such as silica particles supporting dipolar Mie resonances, and illuminating the system with focused light, we demonstrate through rigorous theory the possibility of achieving complete optical coupling, provided the angular profile of the incident light is appropriately shaped, and the surface-scatterer distance is fixed to satisfy the so-called critical coupling conditions.

    The solution here proposed to solve the in and out optical coupling problem has general applicability in nanophotonics and provides a viable route toward the design of compact optical devices in which suitably engineered optical scatterers are used to funnel light into the surface modes of a planar surface, where they can be used for optical sensing or signal processing, and eventually coupled out into propagating light following the same scheme.

  • New breast cancer precision medicine approach to prevent metastasis: from bench to bedside (2021)

    Gomis, Roger (IRB Barcelona)

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    New breast cancer precision medicine approach to prevent metastasis: from bench to bedside

    Currently, bisphosphonates are not regulatory approved for its use in adjuvant treatment of early-stage breast cancer patients. However, they are recommended in the ASCO/ESMO guidance for clinical practice for adjuvant treatment of breast cancer of postmenopausal patients.


    The results from this study show that, independent of menopausal status, patients with MAF-negative (non-amplified) tumors treated with Clodronate had a longer survival than untreated patients (HROS= 0·59, (95% CI 0·37–0·93), p=0·02), whereas patients who had MAF-positive tumors had no benefit. The risk of death at 5 years in MAF-negative patients was reduced by 41% with clodronate adjuvant treatment. MAF-negative patients who benefited from clodronate adjuvant treatment in this study represented around 80% of all breast cancer patients.


    Our results indicate that the clinical benefit of adjuvant clodronate use is restricted to MAF-negative patients. The assessment of MAF status has the potential to become an objective approach to selection of breast cancer patients for adjuvant clodronate treatment, improving the clinical outcome of the patients.


    The MAF gene amplification acts like an orchestra conductor, activating and blocking a large number of genes, and it plays a key role in breast cancer metastasis, particularly in the spread to the bone. It regulates processes such as cell survival, the initiation of metastasis, metabolic rewiring, and also adhesion to cells from the bone marrow, and the formation of osteoclasts, a cell types responsible for remodeling bone.

    The MAF test is developed by Inbiomotion, a spin-off from IRB Barcelona and ICREA, the test has been successfully assayed in two clinical trials, involving a total of 6,500 patients.

  • Why are hybrid metal-halide perovskites so defect tolerant? (2021)

    Goñi, Alejandro R. (CSIC - ICMAB)

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    Why are hybrid metal-halide perovskites so defect tolerant?

    Hybrid lead halide perovskites are causing a revolution in photovoltaics, reaching light conversion efficiencies in excess of 25% after less than a decade of intense research. In nanocrystal form, these materials exhibit light-emission quantum yields close to 100%, which make them excellent candidates for light emitting devices too. However, a feature making hybrid perovskites so attractive for commercialization is the fact that they are produced by low-temperature, hence low-cost, scalable solution-based methods. In part as a consequence, hybrid perovskites are mechanically soft ionic solids with low energetic barriers for point-defect formation and yet they exhibit excellent optoelectronic properties. This can be explained if most native point defects (vacancies, interstitials and antisite defects) are shallow. Unlike deep traps, which are highly localized centers exhibiting high charge-carrier trapping rates, shallow defects are benign as far as the charge-carrier recombination is concerned. Shallow defects can be studied by means of low-temperature photoluminescence (PL). In PL experiments, correlated electron-hole pairs, called excitons, are excited with a laser. Excitons move freely through the crystal, like a binary-stars system, but they can become bound to different shallow defects. Free or bound excitons recombine radiatively emitting photons with precise energies, constituting an optical fingerprint (see Fig. 1). 

    In a recent work [1], we performed the first systematic study of the evolution of shallow-defect signatures observed in low-temperature PL spectra of mixed organic-cation lead iodide perovskite single crystals. Based on state-of-the-art ab initio calculations, we were able to provide a first assignment for all PL features to different shallow-defects (vacancies & interstitials) of hybrid perovskites. 

    In this way, our results provide a deeper insight into fundamental aspects of the photo-physics of native shallow defects in metal halide perovskites. This is instrumental for the optimization and further development of photovoltaic as well as light-emitting devices, based on this class of extraordinary semiconductor materials.

  • What big eyes you have! (2021)

    Gorostiza Langa, Pau (IBEC)

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    What big eyes you have!

    Can pupils dilate with light? they usually do the opposite, as they are intended to adjust to the ambient light intensity. That is why a common test performed by eye doctors to examine the optic nerve and retina, or in ophthalmological shops to evaluate visual performance, requires to dilate the pupil with a drug. But pupil dilation is annoying, as it causes blurry vision, increased light sensitivity, and increased ocular pressure long after the test.

    A common way to induce pupil dilation is to use agonists of adrenoceptors, proteins that are expressed on the iris dilator muscle, but also in almost any organ and tissue of the human body, where they regulate important physiological functions such as heart and respiratory rate, digestion, vascular tone, and gland secretion, besides pupil diameter.

    These receptors can now be “turned on and off” locally using a set of photoswitchable molecules that we called “adrenoswitches.” These compounds enable remote control over a variety of physiological functions simply using illumination. And the eye offers a perfect window to demonstrate it. Eye-dilating agents (mydriatics) are used in several ophthalmic procedures. However, post-exam pupil dilation can impede simple everyday tasks like driving or reading for several hours. In order to avoid that, we envisaged a drug that would dilate the pupil only during the examination, and then be deactivated as soon as the lights went off.

    When tested in blind mice, whose pupils do not respond to illumination, adrenoswitch-1 evoked a pupil dilation that reversed upon removal of the activating light source. In wild type animals, it inhibited the pupil contraction reflex when this was induced by violet light.

  • A biosensor made of photosynthetic complexes from plants (2021)

    Gorostiza Langa, Pau (IBEC)
    van Hulst, Niek F. (ICFO)

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    A biosensor made of photosynthetic complexes from plants

    Photosynthetic reactions in plants, algae, and cyanobacteria are driven by photosystem protein complexes, which exchange electrons with partner biomolecules. Photosynthetic complexes can also bind synthetic organic molecules, which mediates their photoactivity and enables sensing of herbicides and algicides, or the study of electron transport chains. Thus, development, characterization, and sensing of photosystem complexes bears both fundamental and applied interest. Binding to the plastoquinone sites of photosystem-I provides a promising route to biosensing, and would enable identifying novel substances displaying phytotoxic effects, including those obtained from natural product extracts. To this end, we have devised a procedure to attach photo- and redox-active photosystem I complexes to the surface of transparent gold, and we obtained reproducible electrochemical photo-responses with direct current readout. Using this novel biosensing platform, we measured photocurrents in the presence of the viologen derivative paraquat at concentrations as low as 100 nM, with a biosensor dynamic range spanning six orders of magnitude up to 100 mM concentration.