Artificial Light-Harvesting System Based on Zinc Porphyrin and Benzimidazole: Construction, Resonance Energy Transfer, and Amplification Strategy for Electrochemiluminescence.

Constructing robust and efficient luminophores is of significant importance in the development of electrochemiluminescence (ECL) amplification strategies. Inspired by the resonance energy transfer in natural light-harvesting systems, we propose a novel ECL amplification system based on ECL resonance energy transfer (ECL-RET), which integrates two luminophores, benzimidazole (BIM) and zinc(II) tetrakis(4-carboxyphenyl)porphine (ZnTCPP), into one framework. Through disassembling and reconstruction processes, numerous BIM surround ZnTCPP in the constructed ZIF-9-ZnTCPP. Combined with the overlapped spectra between the emission of BIM and the absorption of ZnTCPP, the energy of multiple BIM (donor) can be concentrated to a single ZnTCPP (acceptor) to amplify the ECL emission of the acceptor. This work provides a convenient way to design an efficient ECL-RET system, which initiates a brand-new chapter in the development of ECL amplification strategies.

2D Zn-Porphyrin-Based Co(II)-MOF with 2-Methylimidazole Sitting Axially on the Paddle-Wheel Units: An Efficient Electrochemiluminescence Bioassay for SARS-CoV-2.

High electrocatalytic activity with tunable luminescence is crucial for the development of electrochemiluminescence (ECL) luminophores. In this study, a porphyrin-based heterobimetallic 2D metal organic framework (MOF), [(ZnTCPP)Co2(MeIm)] (1), is successfully self-assembled from the zinc(II) tetrakis(4-carboxyphenyl)porphine (ZnTCPP) linker and cobalt(II) ions in the presence of 2-methylimidazole (MeIm) by a facile one-pot reaction in methanol at room temperature. On the basis of the experimental results and the theoretical calculations, the MOF 1 contains paddle-wheel [Co2(-CO2)4] secondary building units (SBUs) axially coordinated by a MeIm ligand, which is very beneficial to the electron transfer between the Co(II) ions and oxygen. Combining the photosensitizers ZnTCPP and the electroactive [Co2(-CO2)4] SBUs, the 2D MOF 1 possesses an excellent ECL performance, and can be used as a novel ECL probe for rapid nonamplified detection of the RdRp gene of SARS-CoV-2 with an extremely low limit of detection (≈30 aM).

A flexible ultrasensitive optoelectronic sensor array for neuromorphic vision systems.

The challenges of developing neuromorphic vision systems inspired by the human eye come not only from how to recreate the flexibility, sophistication, and adaptability of animal systems, but also how to do so with computational efficiency and elegance. Similar to biological systems, these neuromorphic circuits integrate functions of image sensing, memory and processing into the device, and process continuous analog brightness signal in real-time. High-integration, flexibility and ultra-sensitivity are essential for practical artificial vision systems that attempt to emulate biological processing. Here, we present a flexible optoelectronic sensor array of 1024 pixels using a combination of carbon nanotubes and perovskite quantum dots as active materials for an efficient neuromorphic vision system. The device has an extraordinary sensitivity to light with a responsivity of 5.1 × 107 A/W and a specific detectivity of 2 × 1016 Jones, and demonstrates neuromorphic reinforcement learning by training the sensor array with a weak light pulse of 1 µW/cm2.

Postsynthesis Ligand Exchange Induced Porphyrin Hybrid Crystalloid Reconstruction for Self-Enhanced Electrochemiluminescence.

In traditional coreactant electrochemiluminescence (ECL), the efficiency of the coreactant catalyzed into an active intermediate is one of the dominant factors restricting the luminous intensity. In this work, Co-2-MI-ZnTCPP is designed as a composite material integrating coreaction accelerator (Co-N) and luminophore. Through the catalytic effect of Co-N structures on hydrogen peroxide, the in situ generation and accumulation of active intermediates are achieved, which will react with porphyrin anion radical, thereby bringing out self-enhanced ECL. By adjusting the scanning potential range, the ECL mechanism is thoroughly studied and the contribution of each potential window to the luminescence is obtained. This work provides inspiration for the design of integrated ECL emitters with a coreaction accelerator and luminophore, providing a new way for the construction of a self-enhanced ECL emitter.

Enhanced Electrochemiluminescence of Porphyrin-Based Metal-Organic Frameworks Controlled via Coordination Modulation.

Precise control over the composition, morphology, and size of porphyrin-based metal-organic frameworks is challenging, but the extension of these hybrid materials will enable the creation of novel electrochemiluminescence (ECL) emitters. The coordination of various entities is made from Zn2+ ions and meso-tetra(4-carboxyphenyl)porphine (TCPP), modulated by both solvent and bathophenanthrolinedisulfonic acid disodium salt (BPS) as capping agent, resulting in limited crystal growth of Zn-TCPP in DMF/H2O (v/v, 1:1) and the formation of nanoscale TCPP-Zn-BPS. The role of BPS is also evaluated using Zn-TCPP and BPS-Zn-TCPP as controls, prepared in the absence of BPS and different coordinating sequences of ligands, respectively. The newly obtained TCPP-Zn-BPS exhibits a variety of different morphologies, as well as spectral and optoelectronic properties. The ECL behavior of TCPP-Zn-BPS is investigated by using H2O2 as co-reactant. The amplification of ECL is further studied by ECL spectroscopies and cyclic voltammetry, with the corresponding mechanism proposed.

ATMP-induced three-dimensional conductive polymer hydrogel scaffold for a novel enhanced solid-state electrochemiluminescence biosensor.

Reliable and sensitive detection of xanthine has important medical and biological significance. In this work, a novel three-dimensional (3D) conductive polymer hydrogel of polyaniline (PAni) was feasibly prepared using aniline (Ani), amino trimethylene phosphonic acid (ATMP) and ammonium persulfate ((NH4)2S2O8) as monomer, gelatinizing agent and oxidizing agent, respectively. Protonation of aniline can be achieved by ATMP, inducing good conductivity of the obtained hydrogel. ATMP remained the chelating abilities in the conductive hydrogel, enabling further immobilization with silver nanoparticles (AgNPs) functionalized by a luminol derivative, N-(aminobutyl)-N-(ethylisoluminol) (ABEI). ABEI-Ag@PAni-ATMP exhibited an enhanced performance of solid-state electrochemiluminescence (ECL). Integrated with xanthine oxidase (XOD), the proposed biosensor can be applied in the detection of xanthine via in-situ generated hydrogen peroxide (H2O2), and present a low detection limit of 9.6 nM, a wide linear range (from 0.01 to 200 µM) and excellent stability.

Carbon-ZnO alternating quantum dot chains: electrostatic adsorption assembly and white light-emitting device application.

Aggregation-induced quenching (ACQ) in carbon nanodots (CNDs) impede their applications in solid devices. Herein, the concept of alternating quantum dot (QD) chains was proposed to overcome the common issue of fluorescence quenching in CNDs; in this study, CNDs and ZnO QDs were interlinked to form carbon-ZnO alternating quantum dot chains (CZA-QDCs), which overcame the ACQ of CNDs and hence ensured efficient full-spectrum fluorescence for white light-emitting devices (WLEDs) without excessive blue emission. Under the excitation of 365 nm lines, white emission resulting from the combination of blue emission from the CNDs and yellow emission from the ZnO QDs has been achieved from these powders. The quantum efficiency of the CZA-QDC powders can reach 49% and remain stable for two months. By coating the powders onto an ultraviolet chip as phosphors, WLEDs with a luminous efficiency of 20.1 lm W-1, color coordinate of (0.30, 0.35), correlated color temperature of 5205 K, and a color rendering index of 84 have been fabricated. Due to the relatively high abundance and eco-friendly characteristics of both carbon and ZnO, the results reported herein may provide a promising alternative to fluorescent phosphors that are widely used in WLEDs.

Ce3+-Doping to Modulate Photoluminescence Kinetics for Efficient CsPbBr3 Nanocrystals Based Light-Emitting Diodes.

Inorganic perovskite CsPbBr3 nanocrystals (NCs) are emerging, highly attractive light emitters with high color purity and good thermal stability for light-emitting diodes (LEDs). Their high photo/electroluminescence efficiencies are very important for fabricating efficient LEDs. Here, we propose a novel strategy to enhance the photo/electroluminescence efficiency of CsPbBr3 NCs through doping of heterovalent Ce3+ ions via a facile hot-injection method. The Ce3+ cation was chosen as the dopant for CsPbBr3 NCs by virtue of its similar ion radius and formation of higher energy level of conduction band with bromine in comparison with the Pb2+ cation to maintain the integrity of perovskite structure without introducing additional trap states. It was found that by increasing the doping amount of Ce3+ in CsPbBr3 NCs to 2.88% (atomic percentage of Ce compared to Pb) the photoluminescence quantum yield (PLQY) of CsPbBr3 NCs reached up to 89%, a factor of 2 increase in comparison with the native, undoped ones. The ultrafast transient absorption and time-resolved photoluminescence (PL) spectroscopy revealed that Ce3+-doping can significantly modulate the PL kinetics to enhance the PL efficiency of doped CsPbBr3 NCs. As a result, the LED device fabricated by adopting Ce3+-doped CsPbBr3 NCs as the emitting layers exhibited a pronounced improvement of electroluminescence with external quantum efficiency (EQE) from 1.6 to 4.4% via Ce3+-doping.

Universal liquid-phase laser fabrication of various nano-metals encapsulated by ultrathin carbon shells for deep-UV plasmonics.

The exploration of localized surface plasmon resonance (LSPR) beyond the usual visible waveband, for example within the ultraviolet (UV) or deep-ultraviolet (D-UV) regions, is of great significance due to its unique applications in secret communications and optics. However, it is still challenging to universally synthesize the corresponding metal nanostructures due to their high activity. Herein, we report a universal, eco-friendly, facile and rapid synthesis of various nano-metals encapsulated by ultrathin carbon shells, significantly with a remarkable deep-UV LSPR characteristic, via a liquid-phase laser fabrication method. Firstly, a new generation of the laser ablation in liquid (LAL) method has been developed with an emphasis on the elaborate selection of solvents to generate ultrathin carbon shells, and hence to stabilize the formed metal nanocrystals. As a result, a series of metal@carbon nanoparticles (NPs), including Cr@C, Ti@C, Fe@C, V@C, Al@C, Sn@C, Mn@C and Pd@C, can be fabricated by this modified LAL method. Interestingly, these NPs exhibit LSPR peaks in the range of 200-330 nm, which are very rare for localized surface plasmon resonance. Consequently, the UV plasmonic effects of these metal@carbon NPs were demonstrated both by the observed enhancement in UV photoluminescence (PL) from the carbon nanoshells and by the improvement of the photo-responsivity of UV GaN photodetectors. This work could provide a universal method for carbon shelled metal NPs and expand plasmonics into the D-UV waveband.

Enhanced Electrochemiluminescence of One-Dimensional Self-Assembled Porphyrin Hexagonal Nanoprisms.

In this work, we synthesized the one-dimensional nanostructure of zinc 5,10,15,20-tetra(4-pyridyl)-21H,23H-porphine (ZnTPyP) via a self-assembly technique. Using sodium dodecyl sulfate (SDS) as "soft template", the self-assembled ZnTPyP (SA-ZnTPyP) had the morphology of hexagonal nanoprisms with a uniform size (diameter of 100 nm). The SA-ZnTPyP exhibited remarkably different spectral properties compared to those of the original ZnTPyP. The as-prepared SA-ZnTPyP was used to modify glassy carbon electrodes (GCE), and the electrochemiluminescence (ECL) behaviors of the SA-ZnTPyP/GCE were investigated. The hydrophilic carbon dots (C-dots) could efficiently prevent the dissolution of SA-ZnTPyP in DMF containing 0.1 mol L-1 TBAP and, simultaneously, could accelerate electron transfer. Therefore, the enhanced ECL was realized by C-dots/SA-ZnTPyP/GCE by using H2O2 as co-reactant. This amplification of ECL was further studied by ECL spectroscopies and cyclic voltammetry, and the corresponding mechanism was proposed.

Carbon dots with high fluorescence quantum yield: the fluorescence originates from organic fluorophores.

In this contribution, we have shown that the organic fluorophores, 5-oxo-3,5-dihydro-2H-thiazolo [3,2-a] pyridine-3,7-dicarboxylic acid (TPDCA) and 5-oxo-3,5-dihydro-2H-thiazolo [3,2-a] pyridine-7-carboxylic acid (TPCA), are the main ingredients and fluorescence origins of N,S-CDs via systematic analyses. It inspires us to deeply analyze and understand the fluorescence origins of carbon dots with high fluorescence quantum yields, which will expand their applications.

Zirconium-metalloporphyrin frameworks as a three-in-one platform possessing oxygen nanocage, electron media, and bonding site for electrochemiluminescence protein kinase activity assay.

A Zr-based metal-organic framework with zinc tetrakis(carboxyphenyl)-porphyrin (ZnTCPP) groups (MOF-525-Zn) was utilized to develop a novel electrochemiluminescence (ECL) biosensor for highly sensitive protein kinase activity assay. In this work, in terms of ECL measurements and cyclic voltammetry, the cathodic ECL behaviors of MOF-525-Zn in aqueous media were thoroughly investigated for the first time. The photoelectric active groups ZnTCPP on the MOF-525-Zn frameworks could promote the generation of singlet oxygen ((1)O2) via a series of electrochemical and chemical reactions, resulting in a strong and stable red irradiation at 634 nm. Additionally, the surfactant tetraoctylammonium bromide (TOAB) further facilitated dissolved oxygen to interact with the active sites ZnTCPP of MOF-525-Zn. Furthermore, the inorganic Zr-O clusters of MOF-525-Zn were simultaneously served as the recognition sites of phosphate groups. And then, an ultrasensitive ECL sensor was proposed for protein kinase A (PKA) activity detection with a linear range from 0.01 to 20 U mL(-1) and a sensitive detection limit of 0.005 U mL(-1). This biosensor can also be applied for quantitative kinase inhibitor screening. Finally, it exhibits good performance with high stability and acceptable fabrication reproducibility, which provide a valuable strategy for clinic diagnostics and therapeutics.