Simple Sol-Gel Protein Stabilization toward Rainbow and White Lighting Devices.

Fluorescent proteins (FPs) are heralded as a paradigm of sustainable materials for photonics/optoelectronics. However, their stabilization under non-physiological environments and/or harsh operation conditions is the major challenge. Among the FP-stabilization methods, classical sol-gel is the most effective, but less versatile, as most of the proteins/enzymes are easily degraded due to the need of multi-step processes, surfactants, and mixed water/organic solvents in extreme pH. Herein, sol-gel chemistry with archetypal FPs (mGreenLantern; mCherry) is revisited, simplifying the method by one-pot, surfactant-free, and aqueous media (phosphate buffer saline pH = 7.4). The synthesis mechanism involves the direct reaction of the carboxylic groups at the FP surface with the silica precursor, generating a positively charged FP intermediate that acts as a seed for the formation of size-controlled mesoporous FP@SiO2 nanoparticles. Green-/red-emissive (single-FP component) and dual-emissive (multi-FPs component; kinetic studies not required) FP@SiO2 are prepared without affecting the FP photoluminescence and stabilities (>6 months) under dry storage and organic solvent suspensions. Finally, FP@SiO2 color filters are applied to rainbow and white bio-hybrid light-emitting diodes featuring up to 15-fold enhanced stabilities without reducing luminous efficacy compared to references with native FPs. Overall, an easy, versatile, and effective FP-stabilization method is demonstrated in FP@SiO2 toward sustainable protein lighting.

Controlling aggregation-induced emission by supramolecular interactions and colloidal stability in ionic emitters for light-emitting electrochemical cells.

Chromophores face applicability limitations due to their natural tendency to aggregate, with a subsequent deactivation of their emission features. Hence, there has been a fast development of aggregation induced emission (AIE) emitters, in which non-radiative motional deactivation is inhibited. However, a fine control of their colloidal properties governing the emitting performance is fundamental for their application in thin film optoelectronics. In addition, ion-based lighting devices, such as light emitting electrochemical cells (LECs), requires the design of ionic AIE emitters, whose structure allows (i) an easy ion polarizability to assist charge injection and (ii) a reversible electrochemical behavior. To date, these fundamental questions have not been addressed. Herein, the hydrophilic/hydrophobic balance of a family of cationic tetraphenyl ethene (TPE) derivatives is finely tuned by chemical design. The hydrophilic yet repulsive effect of pyridinium-based cationic moieties is balanced with hydrophobic variables (long alkyl chains or counterion chemistry), leading to (i) a control between monomeric/aggregate state ruling photoluminescence, (ii) redox behavior, and (iii) enhanced ion conductivity in thin films. This resulted in a LEC enhancement with the first ionic AIE emitters, reaching values of 0.19 lm W-1 at ca. 50 cd m-2. Overall, this design rule will be key to advance ionic active species for optoelectronics.

VARPA: In Silico Additive Screening for Protein-Based Lighting Devices.

Protein optoelectronics is an emerging field facing implementation and stabilization challenges of proteins in harsh non-natural environments, such as dry polymers, inorganic materials, etc., operating at high temperatures/irradiations. In this context, additives promoting structural and functional protein stabilization are paramount to realize highly performing devices. On one hand, trial-error experimental assays based on previous knowledge of classical additives in aqueous solutions are effort/time-consuming, while their translation to water-less matrices is uncertain. On the other hand, computational simulations (molecular dynamics, electronic structure methods, etc.) are limited by the system size and time. Herein, ligand-binding affinity and atomic perturbations to create a day-fast computational method combining Vina And Rosetta for Protein Additives (VARPA) to simulate the stabilization effect of sugars for the archetypal enhanced green fluorescent protein embedded in a standard dry polymer color-converting filter for bio-hybrid light-emitting diodes is merged. The VARPA's sugar additive prediction trend for protein stabilization is nicely validated by thermal and photophysical studies as well as lighting device analysis. The device stability followed the predicted enhanced stability trend, reaching a 40-fold improvement compared to reference devices. Overall, VARPA can be adapted to a myriad of additives and proteins, driving first-step experimental efforts toward highly performing protein devices.

Investigations on the Surface Integrity and Wear Mechanisms of TiAlYN-Coated Tools in Inconel 718 Milling Operations.

Inconel 718 is a Ni superalloy with superior mechanical properties, even at high temperatures. However, due to its high hardness and low thermal conductivity, it is considered a difficult-to-machine material. This material is widely used in applications that require good dimensional stability, making the milling process the most used in machining this alloy. The wear resulting from this process and the quality of the machined surface are still challenging factors when it comes to Inconel 718. TiAlN-based coating has been used on cutting tools with Yttrium as a doping element to improve the process performance. Based on this, this work evaluated the machined surface integrity and wear resistance of cutting tools coated using Physical Vapor Deposition (PVD) HiPIMS with TiAlYN in the end milling of Inconel 718, varying the process parameters such as cutting speed (vc), feed per tooth (fz), and cutting length (Lcut). It was verified that the Lcut is the parameter that exerts the most significant influence since, even at small distances, Inconel 718 already generates high tool wear (TW). Furthermore, the main wear mechanisms were abrasive and adhesive wear, with the development of a built-up edge (BUE) under a125 m/min feed rate (f) and a Lcut = 15 m. Chipping, cracking, and delamination of the coating were also observed, indicating a lack of adhesion between the coating and the substrate, suggesting the need for a good interlayer or the adjustment of the PVD parameters.

A Conformationally Stable π-Expanded X-Type Double Helicene Comprising Dihydropyracylene Units with Multistage Redox Behavior.

A π-expanded X-type double [5]helicene comprising dihydropyracylene moieties was synthesized from commercially available acenaphthene. X-ray crystallographic analysis revealed the unique highly twisted structure of the compound resulting in the occurrence of two enantiomers which were separated by chiral HPLC, owing to their high conformational stability. The compound shows strongly bathochromically shifted UV/vis absorption and emission bands with small Stokes shift and considerable photoluminescence quantum yield and circular polarized luminescence response. The electrochemical studies revealed five facilitated reversible redox events, including three reductions and two oxidations, thus qualifying the compound as chiral multistage redox amphoter. The experimental findings are in line with the computational studies based on density functional theory pointing towards increased spatial extension of the frontier molecular orbitals over the polycyclic framework and a considerably narrowed HOMO-LUMO gap.

Supercharged Fluorescent Protein-Apoferritin Cocrystals for Lighting Applications.

The application of fluorescent proteins (FPs) in optoelectronics is hindered by the need for effective protocols to stabilize them under device preparation and operational conditions. Factors such as high temperatures, irradiation, and organic solvent exposure contribute to the denaturation of FPs, resulting in a low device performance. Herein, we focus on addressing the photoinduced heat generation associated with FP motion and rapid heat transfer. This leads to device temperatures of approximately 65 °C, causing FP-denaturation and a subsequent loss of device functionality. We present a FP stabilization strategy involving the integration of electrostatically self-assembled FP-apoferritin cocrystals within a silicone-based color down-converting filter. Three key achievements characterize this approach: (i) an engineering strategy to design positively supercharged FPs (+22) without compromising photoluminescence and thermal stability compared to their native form, (ii) a carefully developed crystallization protocol resulting in highly emissive cocrystals that retain the essential photoluminescence features of the FPs, and (iii) a strong reduction of the device's working temperature to 40 °C, leading to a 40-fold increase in Bio-HLEDs stability compared to reference devices.

Studying the Degradation of Three Polymers under Different Chlorine Concentrations and Exposure Times.

Due to chlorine's ability to kill bacteria and fungi through a chemical reaction, chlorine solutions are commonly used to clean and disinfect numerous public facilities, although these actions are also dependent to the equipment present in those facilities. Accordingly, the interest in studying its effect when in contact with different materials is obvious. This study was carried out through accelerated degradation tests and various analysis methods (optical microscope, scanning electron microscope, and tensile tests). The objective was to observe the wear presented by three polymeric materials, polyvinyl chloride (PVC), high-density polyethylene (HDPE), and polypropylene (PP), when exposed to chlorine's action in swimming pools and drinking water treatment plants. The resulting effect depends on the chlorine content and the type of contact between the chemical agent and the material. The aim was to select the material less likely to be affected by chlorine through tests and analyses, allowing a longer component life. The use of certain more resistant polymeric materials can drastically reduce maintenance, reducing fundamental factors such as costs, the downtime of municipal facilities, and also the risk to public health. It was concluded that PVC has the most stable behaviour overall when in contact with chlorine solutions.

Superior protein thermophilicity prediction with protein language model embeddings.

Protein thermostability is important in many areas of biotechnology, including enzyme engineering and protein-hybrid optoelectronics. Ever-growing protein databases and information on stability at different temperatures allow the training of machine learning models to predict whether proteins are thermophilic. In silico predictions could reduce costs and accelerate the development process by guiding researchers to more promising candidates. Existing models for predicting protein thermophilicity rely mainly on features derived from physicochemical properties. Recently, modern protein language models that directly use sequence information have demonstrated superior performance in several tasks. In this study, we evaluate the usefulness of protein language model embeddings for thermophilicity prediction with ProLaTherm, a Protein Language model-based Thermophilicity predictor. ProLaTherm significantly outperforms all feature-, sequence- and literature-based comparison partners on multiple evaluation metrics. In terms of the Matthew's correlation coefficient, ProLaTherm outperforms the second-best competitor by 18.1% in a nested cross-validation setup. Using proteins from species not overlapping with species from the training data, ProLaTherm outperforms all competitors by at least 9.7%. On these data, it misclassified only one nonthermophilic protein as thermophilic. Furthermore, it correctly identified 97.4% of all thermophilic proteins in our test set with an optimal growth temperature above 70°C.

Genetically Encoded Oligomerization for Protein-Based Lighting Devices.

Implementing proteins in optoelectronics represents a fresh idea toward a sustainable new class of materials with bio-functions that can replace environmentally unfriendly and/or toxic components without losing device performance. However, their native activity (fluorescence, catalysis, and so on) is easily lost under device fabrication/operation as non-native environments (organic solvents, organic/inorganic interfaces, and so on) and severe stress (temperature, irradiation, and so on) are involved. Herein, a gift bow genetically-encoded macro-oligomerization strategy is showcased to promote protein-protein solid interaction enabling i) high versatility with arbitrary proteins, ii) straightforward electrostatic driven control of the macro-oligomer size by ionic strength, and iii) stabilities over months in pure organic solvents and stress scenarios, allowing to integrate them into classical water-free polymer-based materials/components for optoelectronics. Indeed, rainbow-/white-emitting protein-based light-emitting diodes are fabricated, attesting a first-class performance compared to those with their respective native proteins: significantly enhanced device stabilities from a few minutes up to 100 h keeping device efficiency at high power driving conditions. Thus, the oligomerization concept is a solid bridge between biological systems and materials/components to meet expectations in bio-optoelectronics, in general, and lighting schemes, in particular.

Core-Shell Structured Fluorescent Protein Nanoparticles: New Paradigm Toward Zero-Thermal-Quenching in High-Power Biohybrid Light-Emitting Diodes.

Stable and efficient high-power biohybrid light-emitting diodes (Bio-HLEDs) using fluorescent proteins (FPs) in photon downconverting filters have not been achieved yet, reaching best efficiencies of 130 lm W-1 stable for >5 h. This is related to the rise of the device temperature (70-80 °C) caused by FP-motion and quick heat-transmission in water-based filters, they lead to a strong thermal emission quenching followed by the quick chromophore deactivation via photoinduced H-transfer. To tackle both issues at once, this work shows an elegant concept of a new FP-based nanoparticle, in which the FP core is shielded by a SiO2 -shell (FP@SiO2 ) with no loss of the photoluminescence figures-of-merit over years in foreign environments: dry powder at 25 °C (ambient) or constant 50 °C, as well as suspensions in organic solvents. This enables the preparation of water-free photon downconverting coatings with FP@SiO2 , realizing on-chip high-power Bio-HLEDs with 100 lm W-1 stable for >120 h. Both thermal emission quenching and H-transfer deactivation are suppressed, since the device temperature holds <40 °C and remote high-power Bio-HLEDs exhibit final stabilities of 130 days compared to reference devices with water-based FP@SiO2 (83 days) and FP-polymer coatings (>100 h). Hence, FP@SiO2 is a new paradigm toward water-free zero-thermal-quenching biophosphors for first-class high-power Bio-HLEDs.

Study of the Chlorine Influence on the Corrosion of Three Steels to Be Used in Water Treatment Municipal Facilities.

Many municipal facilities, such as pools and drinking water treatment facilities, are subject to ongoing maintenance due to the corrosion of their metallic materials caused by chlorine, leading to high costs and a possible risk to public health. A proper study of the employed product's effect could lead to the use of better materials, which significantly increase the lifetime of metallic equipment more attacked by corrosion, through studies evaluating their cost-effectiveness. This paper was carried out with the objective of studying the degradation of some metallic materials (AISI 316L, AISI 321 and Duplex 14462) used in the referred facilities in order to select the one that possessed a better behavior. It was observed that the introduction of some more adequate materials can drastically reduce maintenance operations, with Duplex 14462 showing the best results, ideal for greater chlorine concentrations, followed by AISI 321, which may be employed for components in less contact with chlorine, since it is more easily affordable.

The Impact of the Deterioration on Wood by Chlorine: An Experimental Study.

The use of disinfection and cleaning chemicals in several municipal facilities, such as swimming pools and drinking water treatment plants, causes the degradation of various types of wood, which leads to failures in equipment and the corresponding need for maintenance. This degradation creates added costs for municipalities, as well as the closure of certain facilities due to curative or preventive maintenance and, in many cases, public health issues, due to the water being contaminated with deteriorating products. Through a thorough study of the degradation effect on the products, more resistant materials can be found which are able to withstand these adversities and increase the lifespan of wood in regular contact with chemical agents. This is achievable by the determination of the cost-effectiveness of the substitute material to replace these components with alternative ones, with properties that better resist the deterioration effects promoted by aggressive environments. No studies have been found so far strictly focused on this matter. The objective of this study is to evaluate the degradation presented by two types of wood, beech and oak, which are exposed to the action of chlorine in municipal facilities. This degradation varies according to the chlorine content and the materials' time of contact with the chemical agent, allowing the selection of new materials which will provide an extended lifetime of the components, reducing maintenance drastically, as well as costs for the facilities and the risk to public health. The performed experimental tests have shown that the oak wood has the best results regarding chlorine degradation resistance.

Tweaking the Optoelectronic Properties of S-Doped Polycyclic Aromatic Hydrocarbons by Chemical Oxidation.

Peri-thiaxanthenothiaxanthene, an S-doped analog of peri-xanthenoxanthene, is used as a polycyclic aromatic hydrocarbon (PAH) scaffold to tune the molecular semiconductor properties by editing the oxidation state of the S-atoms. Chemical oxidation of peri-thiaxanthenothiaxanthene with H2 O2 led to the relevant sulfoxide and sulfone congeners, whereas electrooxidation gave access to sulfonium-type derivatives forming crystalline mixed valence (MV) complexes. These complexes depicted peculiar molecular and solid-state arrangements with face-to-face π-π stacking organization. Photophysical studies showed a widening of the optical bandgap upon progressive oxidation of the S-atoms, with the bis-sulfone derivative displaying the largest value (E00 =2.99 eV). While peri-thiaxanthenothiaxanthene showed reversible oxidation properties, the sulfoxide and sulfone derivatives mainly showed reductive events, corroborating their n-type properties. Electric measurements of single crystals of the MV complexes exhibited a semiconducting behavior with a remarkably high conductivity at room temperature (10-1 -10-2  S cm-1 and 10-2 -10-3  S cm-1 for the O and S derivatives, respectively), one of the highest reported so far. Finally, the electroluminescence properties of the complexes were tested in light-emitting electrochemical cells (LECs), obtaining the first S-doped mid-emitting PAH-based LECs.

Supramolecular Chalcogen-Bonded Semiconducting Nanoribbons at Work in Lighting Devices.

This work describes the design and synthesis of a π-conjugated telluro[3,2-ß][1]-tellurophene-based synthon that, embodying pyridyl and haloaryl chalcogen-bonding acceptors, self-assembles into nanoribbons through chalcogen bonds. The ribbons π-stack in a multi-layered architecture both in single crystals and thin films. Theoretical studies of the electronic states of chalcogen-bonded material showed the presence of a local charge density between Te and N atoms. OTFT-based charge transport measurements showed hole-transport properties for this material. Its integration as a p-type semiconductor in multi-layered CuI -based light-emitting electrochemical cells (LECs) led to a 10-fold increase in stability (38 h vs. 3 h) compared to single-layered devices. Finally, using the reference tellurotellurophene congener bearing a C-H group instead of the pyridyl N atom, a herringbone solid-state assembly is formed without charge transport features, resulting in LECs with poor stabilities (<1 h).

Multivariate Analysis Identifying [Cu(N

White light-emitting electrochemical cells (LECs) comprising only [Cu(N^N)(P^P)]+ have not been reported yet, as all the attempts toward blue-emitting complexes failed. Multivariate analysis, based on prior-art [Cu(N^N)(P^P)]+ -based thin-film lighting (>90 papers) and refined with computational calculations, identifies the best blue-emitting [Cu(N^N)(P^P)]+ design for LECs, that is, N^N: 2-(4-(tert-butyl)phenyl)-6-(3,5-dimethyl-1H-pyrazol-1-yl)pyridine and P^P: 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene, to achieve predicted thin-film emission at 490 nm and device performance of 3.8 cd A-1 @170 cd m-2 . Validation comes from synthesis, X-ray structure, thin-film spectroscopic/microscopy/electrochemical characterization, and device optimization, realizing the first [Cu(N^N)(P^P)]+ -based blue-LEC with 3.6 cd A-1 @180 cd m-2 . This represents a record performance compared to the state-of-the-art tricoordinate Cu(I)-complexes blue-LECs (0.17 cd A-1 @20 cd m-2 ). Versatility is confirmed with the synthesis of the analogous complex with 2-(4-(tert-butyl)phenyl)-6-(3,5-dimethyl-1H-pyrazol-1-yl)pyrazine (N^N), showing a close prediction/experiment match: λ = 590/580 nm; efficiency = 0.55/0.60 cd A-1 @30 cd m-2 . Finally, experimental design is applied to fabricate the best white multicomponent host:guest LEC, reducing the number of trial-error attempts toward the first white all-[Cu(N^N)(P^P)]+ -LECs with 0.6 cd A-1 @30 cd m-2 . This corresponds to approximately ten-fold enhancement compared to previous LECs (<0.05 cd A-1 @<12 cd m-2 ). Hence, this work sets in the first multivariate approach to design emitters/active layers, accomplishing first-class [Cu(N^N)(P^P)]+ -based blue/white LECs that were previously elusive.

Towards rainbow photo/electro-luminescence in copper(i) complexes with the versatile bridged bis-pyridyl ancillary ligand.

The synthesis and characterization of a family of copper(i) complexes bearing a bridged bis-pyridyl ancillary ligand is reported, highlighting how the bridge nature impacts the photo- and electro-luminescent behaviours within the family. In particular, the phosphonium bridge led to copper(i) complexes featuring good electrochemical stability and high ionic conductivity, as well as a stark blue-to-orange luminescence shift compared to the others. This resulted in high performance light-emitting electrochemical cells reaching stabilities of 10 mJ at ca. 40 cd m-2 that are one order of magnitude higher than those of the other complexes. Overall, this work sheds light onto the crucial role of the bridge nature of the bis-pyridyl ancillary ligand on the photophysical features, film forming and, in turn, on the final device performances.

In Situ Ambient Preparation of Perovskite-Poly(l-lactic acid) Phosphors for Highly Stable and Efficient Hybrid Light-Emitting Diodes.

Metal halide perovskite (MHP)-based phosphor-converted light-emitting diodes (pc-LEDs) are limited by the low MHP stability under storage/operation conditions. A few works have recently established the in situ synthesis of MHPs into polymer matrices as an effective strategy to enhance the stability of MHP with a low-cost fabrication. However, this is limited to petrochemical-based polymers. Herein, the first in situ ambient preparation of highly luminescent and stable MHP-biopolymer filters (MAPbBr3 nanocrystals as an emitter and poly(l-lactic acid) (PLLA) as the matrix) with arbitrary areas (up to ca. 300 cm2) is reported. The MAPbBr3-PLLA phosphors feature a narrow emission (25 nm) with excellent photoluminescence quantum yields (>85%) and stability under ambient storage, water, and thermal stress. This is corroborated in green pc-LEDs featuring a low-efficiency roll-off, an excellent operational stability of ca. 600 h, and high luminous efficiencies of 65 lm W-1 that stand out compared to the prior state of the art (e.g., an average lifetime of 200 h at 50 lm W-1). The filters are further exploited to fabricate white-emitting pc-LEDs with efficiencies of ca. 73 lm W-1 and x/y CIE color coordinates of 0.33/0.32. Overall, this work establishes a straightforward (one-pot/in situ) and low-cost preparation (ambient/room temperature) of highly efficient and stable MHP-biopolymer phosphors for highly performing and more sustainable lighting devices.

Transparent and flexible high-power supercapacitors based on carbon nanotube fibre aerogels.

In this work, we report the fabrication of continuous transparent and flexible supercapacitors by depositing a CNT network onto a polymer electrolyte membrane directly from an aerogel of ultra-long CNTs produced floating in the gas phase. The supercapacitors show a combination of a power density of 1370 kW kg-1 at high transmittance (ca. 70%), and high electrochemical stability during extended cycling (>94% capacitance retention over 20 000 cycles) and against repeated 180° flexural deformation. They represent a significant enhancement of 1-3 orders of magnitude compared to prior state-of-the-art transparent supercapacitors based on graphene, CNTs, and rGO. These features mainly arise from the exceptionally long length of CNTs, which makes the material behave as a bulk conductor instead of an aspect ratio-limited percolating network, even for electrodes with >90% transparency. The electrical and capacitive figures-of-merit for the transparent conductor are FoMe = 2.7, and FoMc = 0.46 F S-1 cm-2 respectively.

Revealing the Impact of Heat Generation Using Nanographene-Based Light-Emitting Electrochemical Cells.

Self-heating in light-emitting electrochemical cells (LECs) has been long overlooked, while it has a significant impact on (i) device chromaticity by changing the electroluminescent band shape, (ii) device efficiency because of thermal quenching and exciton dissociation reducing the external quantum efficiency (EQE), and (iii) device stability because of thermal degradation of excitons and eliminate doped species, phase separation, and collapse of the intrinsic emitting zone. Herein, we reveal, for the first time, a direct relationship between self-heating and the early changes in the device chromaticity as well as the magnitude of the error comparing theoretical/experimental EQEs-that is, an overestimation error of ca. 35% at usual pixel working temperatures of around 50 °C. This has been realized in LECs using a benchmark nanographene-that is, a substituted hexa-peri-hexabenzocoronene-as an emerging class of emitters with outstanding device performance compared to the prior art of small-molecule LECs-for example, luminances of 345 cd/m2 and EQEs of 0.35%. As such, this work is a fundamental contribution highlighting how self-heating is a critical limitation toward the optimization and wide use of LECs.

White-emitting Protein-Metal Nanocluster Phosphors for Highly Performing Biohybrid Light-Emitting Diodes.

This work presents a simple in situ synthesis and stabilization of fluorescent gold nanoclusters (AuNCs) with different sizes using engineered protein scaffolds in water. The protein-AuNC hybrids show a dual emission (450 and 700 nm) with a record photoluminescence quantum yield of 20%. These features impelled us to apply them to biohybrid light-emitting diodes as color down-converting filters or biophosphors. Efficient white emission (x/y CIE color coordinates of 0.31/0.29) and stabilities of more than 800 h were achieved. This represents a 2 orders of magnitude enhancement compared to the prior art. Besides the outstanding performance, the protein scaffold also infers a unique anisotropic emission character that is considered as a proof-of-concept of high interest for single-point lighting and display.