Compositionally engineered metal-organic frameworks (MOFs) have been designed and used to fabricate ultrafast scintillating films with emission in both the UV and visible regions. The inclusion of hafnium (Hf) ions in the nodes of the MOF increases the interaction cross-section with ionizing radiation, partially compensating for the low density of the porous material and dramatically increasing the system scintillation yield. The high diffusivity of bimolecular excitons within the framed conjugated ligands allows bimolecular annihilation processes between excited states that partially quench the MOF luminescence, resulting in ultrafast scintillation pulses under X-ray excitation with kinetics in the hundreds of picoseconds time scale. Despite the quenching, the gain in scintillation yield achieved by incorporating Hf ions is large enough to maintain the light yield of the films above 104 ph/MeV under soft X-rays. These unprecedented high efficiencies and simultaneous ultrafast emission kinetics obtained at room temperature in a technologically attractive solid-state configuration, together with the versatility of its composition allowing for further application-specific modifications, place the MOF platform in a prominent position for the realization of the next generation of ultrafast scintillation counters for high-energy physics studies and medical imaging applications.

Natural radioactive gases and anthropogenic radionuclides such as radon, xenon, hydrogen and krypton isotopes, need to be carefully monitored to be properly managed as pathogenic agents, radioactive diagnostic agents or indicators of nuclear activity. State-of-the-art gas detectors based on liquid scintillators suffer from many drawbacks such as lengthy sample preparation procedures and limited solubility of gaseous radionuclides, which produces a detrimental effect on measurement sensitivity. A potential breakthrough solution to this problem is using solid porous scintillators that act as gas concentrators and, therefore, could increase detection sensitivity. Highly porous scintillating metal-organic frameworks (MOFs) stand out as relevant materials for the realization of these devices. We demonstrate the capability of porous hafnium-based MOF nanocrystals exploiting dicarboxy-9,10-diphenylanthracene (DPA) as a scintillating conjugated ligand to detect gas radionuclides. The nanocrystals show fast scintillation properties in the nanosecond domain, a fluorescence quantum yield of ~40% and an accessible porosity suitable to host noble gas atoms and ions. The adsorption and detection of radionuclides such as 85Kr, 222Rn and 3H have been explored for these MOFs utilising a newly developed device based on a time coincidence technique. MOF nanocrystals demonstrate an improved sensitivity for these radionuclides compared to a reference detector, showing an excellent linear response down to an activity value lower than 1 kBq·m-3 that outperforms commercial devices. These results strongly support the possible use of scintillating porous MOF nanocrystals as the building block of ultrasensitive sensors for detecting natural and anthropogenic radioactive gases.

Abstract Sensitized triplet–triplet annihilation photon upconversion (sTTA‐UC) allows blue‐shifting non‐coherent low‐intensity light and is potentially useful in solar‐powered devices, bioimaging, 3D printing, and other applications. For technologically viable solar energy harvesting systems, solid materials that capture a large fraction of the solar spectrum and efficiently upconvert the absorbed energy must be developed. Here, it is shown that broadband‐to‐blue UC is possible in air‐tolerant, easy‐to‐access, nanostructured polymers comprising a rigid hydrophilic matrix and liquid nanodroplets with dimensions on the order of tens of nanometers. The droplets contain 9,10‐bis[(triisopropylsilyl)ethynyl] anthracene (TIPS‐Ac) as emitter/annihilator and palladium(II) octaethyl porphyrin (PdOEP) and palladium(II) meso‐tetraphenyl tetrabenzoporphine (PdTPBP) as sensitizers. The confinement of the three dyes in the liquid domains renders the various bimolecular energy transfer processes that are pivotal for the TIPS‐Ac's triplet sensitization highly efficient, and the simultaneous use of multiple light harvesters with triplet energy levels resonant with the emitter/annihilator increases the absorption bandwidth to ca. 150 nm. The UC process at low power densities is most efficient when both sensitizers are simultaneously excited, thanks to their confinement in the nanodroplets, which leads to an increase in the triplet density, and therefore TTA rate and yield, optimizing the use of the harvested energy.

Hospitals and other healthcare facilities harbor a complex interplay of microbial pathogens. The correct understanding of pathogens distribution and evolution is therefore crucial for infections control and for the design of effective prevention strategies. In parallel, the integration of cutting-edge nanotechnologies for the early detection and monitoring of these specific target pathogens is considered the most effective approach to face nosocomial infections. In this context, point-of-care (POC) testing, also known as near-patient testing, is becoming increasingly important. In this review we provide a systematic insight into the recent scientific and technological advances in pathogen detection that explore advanced nanotechnologies to realize devices and nanobiosensors, with improved selectivity and sensitivity. In particular, we report on the most diffused and affordable nanotechnologies developed and still developing for POC testing, with the aim to increase the sensitivity, speed and accuracy of pathogens detection in different environments, from intensive care units to outside the laboratory and hospital settings. The text is sub-divided in several sections, each one focused on different type of nanomaterials and techniques actually employed.

Ultraviolet (UV) light plays a central role in applications ranging from photochemistry to sterilization and water treatment. However, its low abundance in sunlight (∼10%) limits the direct solar use of UV-driven processes. Sensitized triplet-triplet annihilation upconversion (TTA-UC) offers a promising route to generate UV light from visible light under low-power excitation. Yet, molecular systems capable of efficient visible-to-UV TTA-UC remain scarce. Here, we demonstrate that 1,4-bis(phenylethynyl)benzene (BPEB) and its alkoxylated derivative serve as efficient UV-emitting annihilators when paired with the visible-light sensitizer Ir(ppy)3 in toluene solution. These systems achieve upconverted emission centered at 380 nm, with anti-Stokes shifts exceeding 0.6 eV with respect to excitation energy and threshold excitation intensities as low as 11.5 mW cm-2. Spectroscopic studies suggest that modulation of high-energy excited-state dynamics plays a key role in optimizing upconversion performance. By broadening the molecular design space of UV-emitting annihilators beyond traditional polycyclic aromatics, this study provides a foundation for future development of low-intensity visible-to-UV TTA-UC systems. These findings expand the molecular toolkit for photonic applications where UV emission from ambient light is required.

Photodynamic therapy (PDT) is an efficient, clinically approved, light-activated cancer treatment. However, it is mostly effective for superficial treatments of the skin and mucous membranes due to the limited penetration length of the excitation beam. X-ray-activated PDT (X-PDT) stands out as an emerging alternative. It exploits a radiosensitization effect to enhance the production of reactive oxygen species (ROS), including singlet oxygen (SO), in deep tissues. This radiosensitization is activated by high-Z and dense NPs coupled to PDT agents, which are injected to trigger localized energy release when activated by PDT. To address the common stability and solubility issues associated with NPs and PDT agents, we have developed a hybrid core-shell nanosystem of size 30-35 nm comprising a dense gold nanoparticle (AuNP) coated with a dye-impregnated, biocompatible polymer shell of ca. 6 nm. This design provides colloidal stability and PDT functionality. We investigated the structural, physicochemical, and luminescence properties of these core-shell nanoparticles to demonstrate the effectiveness of PDT dye impregnation. Under X-rays, we observed sensitized SO production in water at ultralow concentrations of radiosensitizers, indicating the effectiveness of our strategy for developing X-PDT agents.

The controlled synthesis of biocompatible nanomaterials with tailored composition, size, and functionalities has driven the advancement of nanomedicine, enabling the development of innovative diagnostic and therapeutic strategies. A key challenge in this field is the design of nano-objects exhibiting multiple functionalities, each dedicated to a specific diagnostic or therapeutic purpose. Among these, synthetic stoichiometric chrysotile nanotubes stand out as a highly biocompatible class of non-carbon nanotubes, already demonstrating their potential for diverse applications, including fluorescence, magnetism, singlet-oxygen generation, and scintillation. Expanding this functional versatility, we report a finely tunable approach for controlling the surface silanization using 3-aminopropyl-trimethoxysilane. This is achieved via a microwave-assisted synthesis, which enables mild reaction conditions and significantly reduces processing time. A comprehensive multi-technique characterization is employed to elucidate the structural and chemical features of the mineral-silane interface and the underlying reaction mechanism.

The formation of porous crystalline structures of a series of Zr-MOFs comprising two coligands (dimethyl-terphenylene and diphenylanthracene dicarboxylates, TP and DPA, respectively) with varying ratios offered the opportunity to investigate systematically the modulation of the accessible pore volumes. These MOF structures exhibit large octahedral cavities of common diameter, while the tetrahedral cavity sizes vary in the series and are gradually reduced with increasing anthracene-based ligand. At low loadings, xenon atoms concentrate in the most energetically favorable corners of the tetrahedral cavities. The application of multiple investigation techniques, such as synchrotron-radiation X-ray diffraction of Xe-loaded crystalline powders, Xe adsorption isotherms, and grand canonical Monte Carlo (GCMC) simulations, allows for determining gas location and interaction energy with the pore walls. The remarkable Xe adsorption energy of 25.4 kJ/mol at low coverage was obtained for the more effective confinement-sites of homoligand Zr-DPA. Additionally, hyperpolarized Xe-129 NMR chemical shifts, collected at very low Xe partial pressure (2% Xe dilution), increased from 78.5 to 94.0 ppm, with increasing DPA ligand content. GCMC sorption simulations of the gas mixture with the same composition as that used for the hyperpolarized NMR experiments show remarkable Xe capture and 99% Xe located in the tetrahedral corners.

Fast photoluminescence and scintillation with a Stokes shift larger than 1 eV is achieved in hetero-ligand metal-organic framework (MOF) crystals comprising inorganic linking nodes and fluorescent conjugated ligands. By finely engineering the MOF composition with the use of ligands with strictly complementary emission and absorption properties and highly delocalized molecular electronic orbitals, the singlet excitons diffusion is enhanced through the ligand framework, fully exploiting both F & ouml;rster and Dexter energy transfer mechanisms. This allows for the sensitization of energy acceptor ligand fluorescence by ultrafast non-radiative energy transfer with a rate up to the THz range. This efficient antenna effect instantly activates the MOF scintillation with a Stokes shift as large as 1.3 eV in the blue spectral range, matching the highest sensitivity spectral window of the best photodetector available. This is obtained using a minimal doping level of the energy acceptor species, with a consequent elimination of emission re-absorption that allows the achievement of a 500% increment of the MOFs scintillation efficiency and the detection of the radioactive krypton isotope 85Kr from the gas phase with an improved sensitivity compared with the reference material.

Several small to medium-scale magnetic confinement fusion devices operate using deuterium as fuel. These low neutron rate (108–1010 n/s) devices rely on 2.45 MeV neutron measurements to validate physical models and to assess their performance. Given the modest rate, neutron monitors have to be placed as close as possible to the machine to maximize data gathering. In these regions, intense stray magnetic fields could affect the detector’s performance. In this work, the development of a neutron detector based on an EJ-276D scintillator crystal coupled with a SiPM and a custom-made readout system is presented. The detector has particle discrimination capability and is insensitive to magnetic fields.

Exosomes are promising therapeutics for tissue repair and regeneration to induce and guide appropriate immune responses in dystrophic pathologies. However, manipulating exosomes to control their biodistribution and targeting them in vivo to achieve adequate therapeutic benefits still poses a major challenge. Here we overcome this limitation by developing an externally controlled delivery system for primed annexin A1 myo-exosomes (Exomyo). Effective nanocarriers are realized by immobilizing the Exomyo onto ferromagnetic nanotubes to achieve controlled delivery and localization of Exomyo to skeletal muscles by systemic injection using an external magnetic field. Quantitative muscle-level analyses revealed that macrophages dominate the uptake of Exomyo from these ferromagnetic nanotubes in vivo to synergistically promote beneficial muscle responses in a murine animal model of Duchenne muscular dystrophy. Our findings provide insights into the development of exosome-based therapies for muscle diseases and, in general, highlight the formulation of effective functional nanocarriers aimed at optimizing exosome biodistribution. Exosome targeting for therapeutic needs remains a challenge. Here, the authors show that ferromagnetic-nanotube-passivated exosomes promote the transition of proinflammatory macrophages to an anti-inflammatory state and myogenic maturation of dystrophic muscle progenitors in a murine model.

Triplet-triplet annihilation (TTA), or triplet fusion, is a biexcitonic process in which two triplet-excited molecules can combine their energy to promote one into an excited singlet state. To alleviate the dependence of the TTA rate and yield on triplet diffusion in both solid and solution environments, intramolecular TTA (intra-TTA) has been recently proposed in conjugated molecular systems able to hold multiple triplet excitons simultaneously. Developing from the previous demonstration of TTA performance enhancement in sensitized upconversion solutions, here similar improvements in triplet harvesting in solid-state films are reported under electrical excitation in organic light emitting diodes (OLEDs). At low dye concentration and low current densities, the intra-TTA active OLED shows a +40% improved external quantum efficiency with respect to the reference device, and a TTA spin-statistical factor f 4DPA of 0.4, close to that determined in fluid solution for the individual chromophore (0.45). These results therefore indicate the utility of this molecular design strategy across a wider range of TTA applications, and with particular utility in the further development of low-power TTA-enhanced OLEDs. The intramolecular triplet-triplet annihilation in conjugated molecular systems able to hold multiple triplet excitons simultaneously boosts by +40% the external quantum yield in blue-emitting organic light emitting diodes (OLEDs), suggesting the utility of this molecular design strategy across the range of triplet-triplet annihilation (TTA) applications and with particular utility in the development of low-power TTA-enhanced OLEDs. image

Scintillating materials emit light when exposed to ionizing radiation or particles and are used for the detection of nuclear threats, medical imaging, high-energy physics, and other usages. For some of these applications, it is vital to distinguish neutrons and charged particles from γ-rays. This is achievable by pulse shape discrimination (PSD), a time-gated technique, which exploits that the scintillation kinetics can depend on the nature of the incident radiation. However, it proves difficult to realize efficient PSD with plastic scintillators, which have several advantages over liquid or crystalline scintillating materials, including mechanical robustness and shapeability. It is shown here that sensitive and rapid PSD is possible with nanostructured polymer scintillators that consist of a solid polymer matrix and liquid nanodomains in which an organic dye capable of triplet-triplet annihilation (TTA) is dissolved. The liquid nature of the nanodomains renders TTA highly efficient so that delayed fluorescence can occur at low energy density. The nanostructured polymer scintillators allow discriminating α particles, neutrons, and γ-rays with a time response that is better than that of commercial scintillators. Exploiting that the liquid nanodomains can facilitate energy transfer processes otherwise difficult to realize in solid polymers, an auxiliary triplet sensitizer is incorporated. This approach further increases the scintillator's sensitivity toward α particles and neutrons and other high-energy processes where localized interactions are involved.

Time-of-Flight Positron Emission Tomography is a medical imaging technique, based on the detection of two back-to-back {\gamma}-photons generated from radiotracers injected in the body. Its limit is the ability of employed scintillation detectors to discriminate in time the arrival of {\gamma}-pairs, i.e. the coincidence time resolution (CTR). A CTR < 50 ps that would enable fast imaging with ultralow radiotracer dose. Monolithic materials do not have simultaneously the required high light output and fast emission characteristics, thus the concept of scintillating heterostructure is proposed, where the device is made of a dense scintillator coupled to a fast-emitting light material. Here we present a composite polymeric scintillator, whose density has been increased upon addition of hafnium oxide nanoparticles. This enhanced by +300% its scintillation yield, surpassing commercial plastic scintillators. The nanocomposite is coupled to bismuth germanate oxide (BGO) realizing a multilayer scintillator. We observed the energy sharing between its components, which activate the nanocomposite fast emission enabling a net CTR improvement of 25% with respect to monolithic BGO. These results demonstrate that a controlled loading with dense nanomaterials is an excellent strategy to enhance the performance of polymeric scintillators for their use in advanced radiation detection and imaging technologies.

Brighter fast scintillators are needed for advanced applications to acquire data with high signal-to-noise ratio in short time windows, like in the time-of-flight positron emission tomography (ToF-PET) imaging technique for cancer. A new composite polymeric fast scintillator loaded with high-density hafnium dioxide (HfO2, hafnia) nanoparticles is developed here to be used for detection of the 511 keV gamma-rays employed in ToF-PET. By a fine tuning and engineering of the electronic properties of its components, namely the polymeric matrix, the dense nanoparticles and the embedded fluorescent dye, a highly luminous polymeric scintillating nanocomposite is realized, showing an unprecedented scintillation efficiency for plastic materials and nanosecond-scaled scintillation decay. Nanocomposite films are then coupled to dense bismuth germanate (Bi4Ge3O12, BGO) crystal sheets to fabricate an heterostructured multilayer scintillator as a prototype pixel for ToF-PET scanners. Thanks to the nanocomposite high scintillation efficiency, the prototype detector shows an ultrafast time resolution of 115 ps for 511 keV gamma-rays detection, actually limited by the non-optimal light transport properties in the pixel and by the sensitivity of the employed photodetector.

Crystalline rubrene (RUB) with the orthorhombic structure can be regarded as a workhorse in organic optoelectronics. So far, however, its great potential for device integration has been held back by the struggle to obtain high-quality and photo-oxidation-resistant RUB thin films. Here, we propose an effective strategy to obtain homogeneous, highly crystalline, and oriented RUB thin films, which relies on the spontaneous amorphous-to-crystal transition driven by organic epitaxy occurring at room temperature in vacuum; this crucial process dictates the final morphological, structural, and optoelectronic properties of the film. To probe the kinetics of the transition, we combine ex situ analysis via polarized optical spectroscopy and atomic force microscopy with a photoluminescence investigation carried out in situ, based on monitoring the efficiency of the singlet fission process typical of crystalline RUB. Building on the insights gained, we tune the thin film growth and post-growth parameters to obtain centimeter-scale, highly homogeneous and crystalline RUB thin films, consisting of several mu m-sized and coherently oriented domains, featuring oxidation resistance. We show that the amorphous-to-crystal transition driven by epitaxy is the process behind the growth of rubrene films with single-crystal-like properties. Growth optimisation expedites this transition and greatly improves the homogeneity of the films.

Lead halide perovskite nanocrystals (LHP-NCs) embedded in polymeric hosts are gaining attention as scalable and low-cost scintillation detectors for technologically relevant applications. Despite rapid progress, little is currently known about the scintillation properties and stability of LHP-NCs prepared by the ligand assisted reprecipitation (LARP) method, which allows mass scalability at room temperature unmatched by any other type of nanostructure, and the implications of incorporating LHP-NCs into polyacrylate hosts are still largely debated. Here, we show that LARP-synthesized CsPbBr3 NCs are comparable to particles from hot-injection routes and unravel the dual effect of polyacrylate incorporation, where the partial degradation of LHP-NCs luminescence is counterbalanced by the passivation of electron-poor defects by the host acrylic groups. Experiments on NCs with tailored surface defects show that the balance between such antithetical effects of polymer embedding is determined by the surface defect density of the NCs and provide guidelines for further material optimization.

Silicate nanoparticles, otherwise referred to as very small grains (VSGs) [1], occur in various astrophysical environments. These grains experience substantial processing (e.g., amorphization) during their lifetime in the diffuse interstellar medium due to events such as grain-grain collisions and irradiation [2]. Moreover, several studies have pointed out that the main building blocks of these silicates are O, Si, Fe, Mg, Al and Ca, all elements that are among the principal constituents of the Earth’s surface [3], thus leading to the name “astronomical silicates”. However, the structure and chemical evolution together with the origin of these grains are still poorly understood and intensively debated [4,5]. The aim of this study is the simulation of space weathering processes on olivine single crystals by liquid phase pulsed laser ablation (LP-PLA). The study of the resulting structure of both the target and the ablated material together with their chemical evolution has been carried out by a multiple technique characterization. In particular, spectroscopy and dynamic light scattering measurements, analyses of the electrostatic properties and reactivity to acids and bases on the obtained colloidal solutions of the ablated nanoproducts have been performed and coupled with high-resolution transmission electron microscopy (HR-TEM). Selected olivine target crystals (Fo87) from the São Miguel island (Azores) were analyzed by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDX). LP-PLA experiments were performed with a Nd:YAG laser focused via a singlet lens onto the surface of the target, which was fixed at the bottom of a polystyrene box filled with 4 ml of deionized water (type 1) to immerge it completely. Laser pulses of 5 ns and 100 mJ simulate the timeframe and energy exchange occurring during grain-grain interstellar collisions [6] and they generate a plasma plume at the crystal/liquid interface. The rapid cooling induced by the confining liquid layer brings about the condensation of the chemical vapor it contains with production of a colloidal solution of nanoparticles. These solutions were analyzed by dynamic light scattering techniques and optical absorption spectroscopy in the range from 200 nm to 1100 nm (6.20 eV - 1.13 eV). Absorption measurements on the colloidal solutions have been compared against reference colloidal solutions dispersed in deionized water (i.e. mesoporous silica [SiO2] nanoparticles, brucite [Mg(OH)2] nanoparticles, aluminum hydroxide [Al(OH)3] nanoparticles, chrysotile [Mg3Si2O5(OH)4] nanotubes, and synthetic forsterite [Mg2SiO4] nanoparticles). Moreover, additional absorption analyses have been carried out as a function of the addition of known aliquots of sulfuric acid and sodium hydroxide solutions. TEM/EDS analyses were then performed on the ablated nanoparticles deposited via electrophoresis on C-coated Cu grids and compositional variations of the ablated target were determined by X-ray photo-emission spectroscopy analyses. The size distribution of LP-PLA synthesized nanoparticles is typically multimodal due to aggregation phenomena. Aggregation is consistent with the measured ζ-potential, which is negative with a relatively low absolute value, within the range 30-50 mV. Nonetheless, a recurrent mode is centered at about 2 nm (hydrodynamic diameter) and it is consistent with the measured size distribution obtained by transmission electron microscopy analysis (average nanoparticles diameter around 3-5 nm). Optical absorption measurements on the ejected material show a main band around 215 nm. This feature is very similar to the “B2 band” reported in several studies on silica glass [7] and ascribed to oxygen vacancies, but its nature is still far to be fully understood. We also found that this feature at 215 nm is very common among both Si and Mg compounds (e.g., Si-oxide, Mg-hydroxide, chrysotile). Moreover, additional absorption bands in the range 240-350nm are observed suggesting the formation of new space weathering products as result of the ablation process. Therefore, these results suggest that substantial chemical processing might be expected during space weathering of “typical” interstellar grains into VSGs. Moreover, coupling these experimental results with remote sensing datasets will provide fundamental information about the origin and evolution of these silicate grains. Acknowledgments: M.M is supported by the SIMP PhD thesis award. References: [1] Witt A. N. (2000) Journal of Geophysical Research: Space Physics, 105(A5), 10299-10302. [2] Carrez P. et al. (2002) Meteoritics & Planetary Science, 37, 1599-1614. [3] Henning T. (2010) Annual Review of Astronomy and Astrophysics, 48, 21-46. [4] Draine B. T. (2003) Annual Review of Astronomy and Astrophysics, 41, 241-289. [5] Escatllar A. M. et al. (2019) ACS Earth and Space Chemistry, 3, 2390-2403. [6] Loeffler M. J. et al. (2016) Meteoritics & Planetary Science, 51, 261-275. [7] Skuja L. N. et al. (1984), Solid State Communications, 50, 1069-1072.

Fast emitting polymeric scintillators are requested in advanced applications where high speed detectors with a large signal-to-noise ratio are needed. However, their low density implies a weak stopping power of high energy radiation and thus a limited light output and sensitivity. To enhance their performance, polymeric scintillators can be loaded with dense nanoparticles (NPs). We investigate the properties of a series of polymeric scintillators by means of photoluminescence and scintillation spectroscopy, comparing standard scintillators with a composite system loaded with dense hafnium dioxide (HfO2) NPs. The nanocomposite shows a scintillation yield enhancement of +100% with an unchanged time response. We provide for the first time an interpretation of this effect, pointing out the local effect of NPs in the generation of emissive states upon interaction with ionizing radiation. The obtained results indicate that coupling fast conjugated emitters with optically inert dense NPs could lead to surpassing the actual limits of pure polymeric scintillators.

ESKAPEE pathogens: where we can find them in hospital environments and how to detect them through nanotechnologies devices.