Electrochemiluminescence (ECL) triggered by bipolar electrochemistry (BE) allows combining wireless electrochemical addressing with a simple optical readout, which enables effective analytical applications. A key factor in BE-ECL is the spatial distribution of the ECL-emitting region(s), which depends on the local electric field and the type and shape of the bipolar electrode (BPE). In this work, spatially resolved ECL emission, originating from single or interconnected beads acting as building blocks for BPE arrays was investigated. The impact of the spatial and compositional anisotropy within the BPE array was imaged by the ECL response of the model [Ru(bpy)3]2+/tri-n-propylamine system. This approach allows the design of a versatile and straightforward platform for high-throughput screening and real-time visualization of electrochemical activity within a single BPE with tuneable composition and chemical reactivity. Furthermore, this work may open up new perspectives for multiplexed biosensing of analytes and screening tools with encoded signals in anisotropic electrode arrays.

Electrogenerated chemiluminescence (ECL) offers a powerful platform for converting electrochemical input into light output with high sensitivity and spatiotemporal control. Here, we report a bipolar electrochemiluminescence (BE-ECL) setup based on a rotating disk bipolar electrode (RDBPE) operating under a polarity-reversed pulsed electric field (±ε) to study hydrodynamic effects on the [Ru(bpy)3]2+ annihilation ECL. The square wave switching (SWS) of the electric field generates alternatingly the oxidized and reduced forms of the luminophore that react with each other and generate the ECL emission, whereas the controlled convection efficiently enhances the intensity and spatial distribution of the ECL emission. Temporal modulation of the SWS of the electric field (duty cycle) selectively tunes the relative generation of oxidized and reduced species at each electrode pole, enabling controlled switching of defined regions. Intensity and shape of the ECL emission is governed by the electrochemical-hydrodynamic coupling. This approach opens new avenues for the development of high-resolution detection platforms for spatially and temporally-resolved analysis, based on alternating polarization of the bipolar electrode.

The development of efficient circularly polarized electrochemiluminescence (CP-ECL) probes is still at its infancy and examples are still very limited. Yet, their achievement would enable gathering a readout that carries privileged information on the probe's chiral environment by monitoring luminescence polarization bias with high signal-to-noise ratio. Notwithstanding, this is a highly challenging task and requires judicious chemical engineering of chiral ECL-active emitters. Herein, we aim at expanding the palette of CP-ECL luminophores by presenting a novel class of enantiopure heterobinuclear Ir(III)–Au(I) complexes, which are investigated thoroughly by means of chemical, structural, and (chiro-)optical techniques. The ground and excited state properties are also elucidated by using density functional theory (DFT) approaches including spin-orbital coupling (SOC) perturbation. The chiral-at-metal complexes display luminescence with a polarization bias of the emitted light that is function of the helical arrangement of the coordination sphere around the Ir(III) center. Overall, the photo- and electro-active complexes unraveled in this work combine unparallelly high photoluminescence quantum yield in the orange region, excellent circularly polarized luminescence (CPL) brightness up to 4.5 M −1 cm −1 with a notable ECL activity. Finally, these features provide emitters with CP-ECL efficiency that encompass remarkably by a factor 3.5 that of the well-known benchmark tris -(2,2′-bipyridyl)ruthenium(II).

Tip-enhanced Raman spectroscopy (TERS) is a powerful technique for nanoscale chemical imaging. However, its worldwide expansion is still limited by the challenging fabrication of cheap, robust and efficient TERS tips as optical nanosources to amplify the Raman signal. An original method based on bipolar electrodeposition is described here to prepare gold-coated AFM cantilevers used as TERS tips. This wireless method is simple to implement, cost-effective, and allows for the parallel fabrication of several TERS tips with good reproducibility of the metal thickness and a relatively long lifetime. The TERS activity was confirmed by imaging graphene oxide flakes with high spatial resolution (below 10 nm). A promising yield of 64% was achieved for the fabrication of active TERS tips. Therefore, this method could pave the way for the development of new chemical routes for the preparation of TERS tips and other plasmonic nanostructures.

AbstractMagnesium, a highly reactive alkaline earth metal, acts spontaneously as a strong reducing agent. In this work, the redox reactivity of Mg is fine‐tuned selectively in a wireless manner by means of bipolar electrochemistry (BE). This is demonstrated by mapping the spatial electroactivity of Mg via the electrochemiluminescence (ECL) emission of the Ru(bpy)32+/S2O82− system. Asymmetric ECL patterns are obtained by controlling the applied external electric field. The ECL intensity is increased by up to approximately 80 % at the cathodic extremity whereas a 50 % decrease is observed at the anodic side of a bipolar electrode. Additionally, the influence of the spatial distribution of the electric field on the reactivity of Mg and its concomitant ECL emission is evaluated, producing complex luminescent patterns. These findings, illustrate the wireless modulation of redox reactivity by BE.

Optical readouts have gained a considerable attention due to their high spatial resolution, high signal to noise ratio and fast response times. Among these, light‐emitting diodes (LEDs) as optical transducers enable to encode chemical information in the current passing through the diode and as a consequence in its light emission amplitude. Recently, the synergy between the principle of bipolar electrochemistry and the optical and electric advantages of LEDs have been explored, in order to develop novel and straightforward approaches to visualize chemical information. This has been increasingly exploited in multiple applications ranging from electroanalysis to chiral recognition, dynamic systems, and multimodal imaging. This review aims to highlight the use of endogenous (thermodynamically spontaneous) and exogenous (externally driven) bipolar electrochemistry for the design of wireless optical readouts based on the operating principle of LEDs.

Coupling electrochemistry with optical techniques gives in-depth insights into the interfacial processes in action. In that context, fluorescence confocal laser scanning microscopy (F-CLSM) enables an electrode surface characterization with spatial resolution in the lateral plane (xy) as well as in the axial direction (z), perpendicular to the electrode surface. However, like most optical techniques, fluorescence microscopy has intrinsic limitations, notably in terms of resolution and sensitivity, which are investigated in this contribution by conducting F-CLSM experiments with two disk electrodes of different sizes: a large microelectrode (LME, Ø = 250 μm) and a much smaller so-called ultramicroelectrode (UME, Ø = 18 μm). We demonstrated that the diffusion layers of both microelectrodes can be imaged with sufficient resolution and sensitivity to be quantitatively compared with the simulated concentration profiles. This work highlights the intrinsic technical challenges associated with this kind of coupled experiments, and it discusses the conditions that should be fulfilled to obtain reliable results at the microscale. These results pave the way toward reaction layer imaging down to micrometric resolution and could help decipher complex electrochemical reactions possibly involving transient species.

Light-emitting dynamic systems have attracted significant attention due to their wireless control, high sensitivity, short response-time, and self-mixing capability. Although, among the different propulsion mechanisms, magnetically-driven motion is a common approach, it requires the use of ferromagnetic components and complex electromagnetic set-ups. In this work, a wireless light-emitting monolayer graphene rotor is designed, powered by the synergetic effect between a magnetic field-enhanced electrophoretic propulsion mechanism and electrochemiluminescence (ECL) generated by the model [Ru(bpy)3]2⁺/tri-n-propylamine system. The asymmetric polarization of a graphene monolayer triggers the reduction of water and the oxidation of the luminophore/co-reactant system, resulting in an observable ECL readout. Simultaneously, a Lorentz force, orthogonal to the plane defined by the external electric and magnetic fields, is induced on the charge compensating ionic flux alongside the device. The combination of both physical chemistry processes is the driving force to trigger light emission and rotational displacement. The efficient coupling of the direction of the global applied electric field and the orientation of the magnetic field allows generating a predictable clockwise (CW) and counterclockwise (CCW) rotation of the 2D nanomaterial, which can be monitored by the ECL emission.

The development of efficient circularly polarized electrochemiluminescence (CP‐ECL) probes is still at its infancy and examples are still very limited. Yet, their achievement would enable gathering a readout that carries privileged information on the probe's chiral environment by monitoring luminescence polarization bias with high signal‐to‐noise ratio. Notwithstanding, this is a highly challenging task and requires judicious chemical engineering of chiral ECL‐active emitters. Herein, we aim at expanding the palette of CP‐ECL luminophores by presenting a novel class of enantiopure heterobinuclear Ir(III)–Au(I) complexes, which are investigated thoroughly by means of chemical, structural, and (chiro‐)optical techniques. The ground and excited state properties are also elucidated by using density functional theory (DFT) approaches including spin‐orbital coupling (SOC) perturbation. The chiral‐at‐metal complexes display luminescence with a polarization bias of the emitted light that is function of the helical arrangement of the coordination sphere around the Ir(III) center. Overall, the photo‐ and electro‐active complexes unraveled in this work combine unparallelly high photoluminescence quantum yield in the orange region, excellent circularly polarized luminescence (CPL) brightness up to 4.5 M −1 cm −1 with a notable ECL activity. Finally, these features provide emitters with CP‐ECL efficiency that encompass remarkably by a factor 3.5 that of the well‐known benchmark tris ‐(2,2′‐bipyridyl)ruthenium(II).

We report on intense electrochemiluminescence (ECL) emission from the redox switching of a series of heterobimetallic systems consisting of lanthanide complexes emitting in the near-infrared (NIR) range (Yb3+ and Nd3+) associated with a redox-active carbon-rich ruthenium bipyridyl antenna chelate. The NIR ECL emission was achieved successfully using the same molecular scaffold. Electrochemical reactions between the antenna and the sacrificial ECL coreactant allow for the low-potential redox modulation of the NIR luminescence from Yb3+ and Nd3+. This strategy offers interesting new insights into NIR ECL systems based on inorganic complexes.

The combination of electrochemiluminescence (ECL) and bipolar electrochemistry (BE) has advanced the development of a new generation of optical devices, offering new possibilities for high-efficiency detection and sensing applications. ECL, a luminescent phenomenon triggered at the electrode surface and driven by redox reactions, has become a versatile technique for highly sensitive detection. Meanwhile, BE enables the remote activation of electrochemical processes without the need for a direct electric connection to the electrodes, thus simplifying the design and miniaturization of electrochemical systems. The integration of both technologies optimizes the interaction between luminophores and bipolar electrodes, improving the efficiency of analyte detection and facilitating the implementation of parallel or multiplexed detection strategies, thus increasing precision and repeatability. This synergy has extended the application scope in areas such as bioanalysis, environmental analysis, and pollutant detection. This review analyzes the fundamental principles of ECL and BE, as well as their synergy in advanced systems, covering the design of spatially confined structures that improve the polarization of bipolar electrodes, thus reducing the threshold energy required to activate ECL and enhancing its efficiency. Additionally, the incorporation of dynamic elements, such as rotating electrodes and microfluidic platforms, has facilitated real-time analysis and the visualization of electrochemical processes at both macroscopic and microscopic levels. The combination of ECL and BE technologies has not only expanded diagnostic and monitoring possibilities in autonomous systems, but has also paved the way for the development of the next generation of analytical technologies, with a significant impact on various scientific challenges.

Molecularly imprinted polymers (MIPs) act as "artificial antibodies" offering molecular recognition along with advantages like cost-effective production, versatility, stability, and reusability. These features make MIPs ideal for detecting food contaminants such as mycotoxins, harmful secondary metabolites produced by fungi on cereals, fruits, and vegetables. However, their use as sensors requires a transducer of the analyte binding event. In this work, we report the development of a hybrid light-emitting device for the wireless electroanalysis of zearalenone (ZON), as exemplary mycotoxin with endocrine disrupting activity. Our approach combines the concepts of bipolar electrochemistry (BE) with the fine molecular recognition of a tailored MIP and the optical readout provided by a light-emitting diode (LED). The polymeric-microelectronic hybrid bipolar electrode incorporates a MIP-coated anode and a gold wire cathode to the extremities of a green LED. The MIP responds immediately to the binding of the target mycotoxin, facilitating redox reactions of the electroactive probe ([Fe (CN)6]3-/4-) at each terminal of the bipolar electrode and triggering the emission of light. A correlation between the intensity of the emitted light and the analyte concentration was obtained. By integrating the BE setup with a microfluidic platform, a highly sensitive analytical device has been built, offering a linear ZON quantification range of 10-70 ng mL-1 , suitable for its quantification in food samples.

Glassy carbon electrodes were modified with a CeO2 film and Pt nanoparticles (Pt-CeO2) for electrocatalysis. Interestingly, the oxidation of benzyl alcohol was significantly enhanced when Pt-CeO2 films were prepared by the simultaneous electrodeposition of the two materials, indicating a significant synergistic electrocatalytic activity. Subsequently, bipolar electrochemistry was employed to prepare Pt-CeO2 gradient films. Scanning electrochemical microscopy (SECM) was employed for studying local electrochemical properties at liquid/solid interfaces. SECM allowed mapping the local electrochemical performance of the Pt-CeO2 gradient films for benzyl alcohol oxidation, showing that the reaction rate is proportional to the local Pt-CeO2 surface coverage. Therefore, Pt-CeO2 deposits with different densities along the bipolar electrode offer tunable catalytic performances for benzyl alcohol oxidation. This allows identifying in a fast and straightforward way the optimal conditions for electrocatalytic processes in a more general sense because the approach, illustrated here with one specific reaction, can be easily generalized to other catalytically-active surfaces.

Total-internal-reflection tip-enhanced Raman spectroscopy (TIR-TERS) imaging of amyloid-beta (A beta(1-42)-L34T) fibrils is performed with nanoscale spatial resolution in water, using TERS tips fabricated by bipolar electrodeposition. Ideal experimental parameters are corroborated by both theoretical simulations and TIR-TERS measurements. TIR-TERS imaging reveals the predominant parallel beta-sheet secondary structure of A beta(1-42)-L34T fibrils as well as the nanoscale spatial distribution of tyrosine, histidine, and phenylalanine aromatic amino acids. Their proportion in TERS spectra can be qualitatively explained by the combined effect of their localization in the A beta(1-42)-L34T fibril structure and their molecular orientation with respect to the excitation laser light polarization. Conclusions drawn from the TERS experiments in water corroborate and significantly enrich our previous study in ambient air, thus confirming that hydration has only a marginal impact on the structure of such amyloid fibrils. This first TIR-TERS study in liquid opens fascinating perspectives for future applications in biology.

Context Genomic selection is a promising approach for forest tree breeding. However, its advantage in terms of prediction accuracy over conventional pedigree-based methods is unclear and within-family accuracy is rarely assessed.Aims We used an pedigree-based model (ABLUP) with corrected pedigree data as a baseline reference for assessing the prediction accuracy of genome-based model (GBLUP) at the global and within-family levels in maritime pine ( Pinus pinaster Ait).Methods We sampled 39 full-sib families, each comprising 10 to 40 individuals, to constitute an experimental population of 833 individuals. A stochastic simulation model was also developed to explore other scenarios of heritability, training set size and tagging density.Results Prediction accuracies with GBLUP and ABLUP were similar and accuracy with GBLUP within-family was on average zero with large variation between families. Simulations revealed that the number of individuals in the training set was the principal factor limiting GBLUP accuracy in our study and likely in many forest tree breeding programmes. Accurate within-family prediction is possible if 40-65 individuals per full-sib family are included in the genomic training set, from a total of 1600-2000 individuals in the training set.Conclusion Such conditions lead to a significant advantage of GBLUP over ABLUP in terms of prediction accuracy and more clearly justify the switch to genome-based prediction and selection in forest trees.### Competing Interest StatementThe authors have declared no competing interest.* ABLUP : pedigree-based best linear unbiased prediction BLUP : best linear unbiased prediction CV : cross-validation DEV : stem deviation to verticality DNA : deoxyribonucleic acid EBV : pedigree-based estimated breeding value GBLUP : genome-based best linear unbiased prediction GEBV : genome-based estimated breeding values GS : genomic selection HT : height LD : linkage disequilibrium nTset : training set size nSNP : number of SNP OCS : optimum contribution selection POPr : trees sampled for this study POPs : simulated version of POPr QTL : quantitative trait loci SNP : single nucleotide polymorphism Tset : training set Vset : validation set

Genetically improved forest reproductive materials are now widely accessible in many European countries due to decades of continuous breeding efforts. Tree breeding does not only contribute to higher-value end products but allows an increase in the rate of carbon capture and sequestration, helping to mitigate the effects of climate change. The usefulness of breeding programmes depends on (i) the relevance of the set of selected traits and their relative weights (growth, drought tolerance, phenology, etc.); (ii) the explicit management of targeted and “neutral” diversity; (iii) the genetic gain achieved; and (iv) the efficiency of transferring diversity and gain to the plantation. Several biological factors limit both operational breeding and mass reproduction. To fully realise the potential of tree breeding, the introduction of new technologies and concepts is pivotal for overcoming these constraints. We reviewed several European breeding programmes, examining their current status and factors that are likely to influence tree breeding in the coming decades. The synthesis was based on case studies developed for the European Union-funded B4EST project, which focused on eight economically important tree species with breeding histories and intensities ranging from low-input breeding (stone pine, Douglas-fir and ash) to more complex programmes (eucalyptus, maritime pine, Norway spruce, poplar, and Scots pine). Tree breeding for these species is managed in a variety of ways due to differences in species’ biology, breeding objectives, and economic value. Most programmes are managed by governmental institutes with full or partial public support because of the relatively late return on investment. Eucalyptus is the only tree species whose breeding is entirely sponsored and managed by a private company. Several new technologies have emerged for both phenotyping and genotyping. They have the potential to speed up breeding processes and make genetic evaluations more accurate, thereby reducing costs and increasing genetic gains per unit of time. In addition, genotyping has allowed the explicit control of genetic diversity in selected populations with great precision. The continuing advances in tree genomics are expected to revolutionise tree breeding by moving it towards genomic-based selection, a perspective that requires new types of skills that are not always available in the institutions hosting the programmes. We therefore recognise the importance of promoting coordination and collaboration between the many groups involved in breeding. Climate change is expected to bring in new pests and diseases and increase the frequency of extreme weather events such as late frosts and prolonged droughts. Such stresses will cause slow growth and mortality, reducing forest productivity and resilience. Most of these threats are difficult to predict, and the time-consuming nature of conventional breeding does not allow for an adequate and timely reaction. We anticipate that most breeding programmes will need to revise their selection criteria and objectives to place greater emphasis on adaptive performance, tolerance to multiple environmental stresses, stability in different environments, and conservation of genetic diversity. Testing breeding materials in a variety of environments, including potentially contrasting climates, will become increasingly important. Climate change may also force the incorporation of new genetic resources that provide new useful adaptations, which may involve the use of new, previously unexplored gene pools or hybridisation, with the enormous challenge of incorporating useful alleles without adding along an unfavourable genetic background. Decision-support tools to help landowners and foresters select the best-performing forest reproductive material in each specific environment could also help reduce the impact of climate change.

Global warming threatens the productivity of forest plantations. We propose here the integration of environmental information into a genomic evaluation scheme using individual reaction norms, to enable the quantification of resilience in forest tree improvement and conservation strategies in the coming decades. Random regression models were used to fit wood ring series, reflecting the longitudinal phenotypic plasticity of tree growth, according to various environmental gradients. The predictive ability of the models was considered to select the most relevant environmental gradient, namely a gradient derived from an ecophysiological model and combining trunk water potential and temperature. Even if the individual ranking was preserved over most of the environmental gradient, strong genotype x environment interactions were detected in the extreme unfavorable part of the gradient, which includes environmental conditions that are very likely to be more frequent in the future. Combining genomic information and longitudinal data allowed to predict the growth of individuals in environments where they have not been observed. Phenotyping of 50% of the individuals in all the environments studied allowed to predict the growth of the remaining 50% of individuals in all these environments with a predictive ability of 0.25. Without changing the total number of observations, adding observations in a reduced number of environments for the individuals to be predicted, while decreasing the number of individuals phenotyped in all environments, increased the predictive ability to 0.59, highlighting the importance of phenotypic data allocation. We found that genomic reaction norms are useful for the characterization and prediction of the function of genetic parameters and facilitate breeding in a climate change context.

Electrochemiluminescence (ECL) of the conventional system of [Ru(bpy)3]2+ luminophore and amine-based coreactants is particularly inefficient on noble metal electrodes. This is due to the formation of a passivating oxide layer on the metal surface inhibiting the electro-oxidation of amines like tri-n-propylamine (TPrA) coreactant. Herein, we demonstrated the enhancement of ECL emission on gold surface by hydroxyl radicals attack that are chemically generated with Cu-Fenton reagent. These radicals selectively deactivate the gold active sites and knockout the metal surface asperities that counterintuitively led to an amplification of the ECL emission. Atomic force microscopy shows a massive smoothening of the surface. The electrochemical characterization proves that the involved ECL reaction mechanism switches from direct oxidation to catalytic route, where the kinetics of indirect TPrA oxidation is facilitated on deactivated gold surface. Besides, in situ smoothening of a rough electrode in presence of tandem [Ru(bpy)3]2+/TPrA enables Cu2+ sensing with good reliability and limit of detection. Such atomically smoothened and corrosion-resistant gold surface readily tuned the ECL reactivity and opened new directions on influence of topography and reactivity on ECL mechanisms, thus will be extremely useful for the future development of ECL imaging strategies and highly sensitive ECL sensors.

Purpose of Review In this review, we synthesise current knowledge on trade-offs among traits in key fitness dimensions and identify major research gaps with the intention of laying the groundwork for a rapid advance in tree breeding for multiple objectives as a key contribution to the sustainability of planted forests in the future. Recent Findings Trade-offs among growth, reproduction, defence, stress tolerance and product quality predicted theoretically have been reported experimentally in many breeding programmes. Among these trade-offs, the genetic linkage between resistance against biotic threats and growth (or other relevant traits) is particularly critical for the current and future management of forest genetic resources. Maintaining tree growth and wood quality in the novel environments of the future requires the assessment of genetic correlations of target traits with phenology, closely linked to survival to temperature extremes. Improving our current knowledge on the genetic trade-offs of drought tolerance as a breeding objective in forest trees obligates a more precise definition of both the specific traits and the experimental conditions. Published evidence suggests that common target traits in breeding programmes may trade-off with reproductive success and fire-adaptation, and the simultaneous improvement of growth and wood quality traits still remains as a constraint in traditional tree breeding. Summary Changing environments combined with pests and diseases are challenging plantation forestry worldwide, which implies an urgent need to develop new improvement strategies to build the resilience of forestry for our future environments. It is essential to have a better understanding of how traits interact, especially those important for production, climate and biotic threat resilience, but much of the information is still missing. Since many key trade-offs are affected by the environment, we need new studies under novel environments to forecast levels of multi-trait integration in breeding populations.