Free-standing films that display high strength and high electrical conductivity are critical for flexible electronics, such as electromagnetic interference (EMI) shielding coatings and current collectors for batteries and supercapacitors. 2D Ti3 C2 Tx flakes are ideal candidates for making conductive films due to their high strength and metallic conductivity. It is, however, challenging to transfer those outstanding properties of single MXene flakes to macroscale films as a result of the small flake size and relatively poor flake alignment that occurs during solution-based processing. Here, a scalable method is shown for the fabrication of strong and highly conducting pure MXene films containing highly aligned large MXene flakes. These films demonstrate record tensile strength up to ≈570 MPa for a 940 nm thick film and electrical conductivity of ≈15 100 S cm-1 for a 214 nm thick film, which are both the highest values compared to previously reported pure Ti3 C2 Tx films. These films also exhibit outstanding EMI shielding performance (≈50 dB for a 940 nm thick film) that exceeds other synthetic materials with comparable thickness. MXene films with aligned flakes provide an effective route for producing large-area, high-strength, and high-electrical-conductivity MXene-based films for future electronic applications.

Scalable Manufacturing of Free‐Standing, Strong Ti 3 C 2 T x MXene Films with Outstanding Conductivity

Separating molecules or ions with sub-Angstrom scale precision is important but technically challenging. Achieving such a precise separation using membranes requires Angstrom scale pores with a high level of pore size uniformity. Herein, we demonstrate that precise solute-solute separation can be achieved using polyamide membranes formed via surfactant-assembly regulated interfacial polymerization (SARIP). The dynamic, self-assembled network of surfactants facilitates faster and more homogeneous diffusion of amine monomers across the water/hexane interface during interfacial polymerization, thereby forming a polyamide active layer with more uniform sub-nanometre pores compared to those formed via conventional interfacial polymerization. The polyamide membrane formed by SARIP exhibits highly size-dependent sieving of solutes, yielding a step-wise transition from low rejection to near-perfect rejection over a solute size range smaller than half Angstrom. SARIP represents an approach for the scalable fabrication of ultra-selective membranes with uniform nanopores for precise separation of ions and small solutes. Separating molecules or ions with sub-Angstrom scale precision is important but technically challenging. Here, the authors demonstrate that precise solute-solute separation can be achieved using polyamide membranes formed via surfactant-assembly regulated interfacial polymerization.

/pdf/polyamide-nanofiltration-membrane-with-highly-uniform-sub-34j3jmcw8n.pdf

Polyamide nanofiltration membrane with highly uniform sub-nanometre pores for sub-1 Å precision separation.

Focusing on the use of nanophosphors for in vivo imaging and diagnosis applications, we used thermally stimulated luminescence (TSL) measurements to study the influence of triva- lent lanthanide Ln 3+ (Ln = Dy, Pr, Ce, Nd) electron traps on the optical properties of Mn 2+ -doped diopside-based persistent lumi- nescence nanoparticles. This work reveals that Pr 3+ is the most suitable Ln 3+ electron trap in the diopside lattice, providing optimal trap depth for room temperature afterglow and resulting in the most intense luminescence decay curve after X-ray irradiation. This luminescence dependency toward the electron trap is maintained through additional doping with Eu 2+ , allowing UV-light excitation, critical for bioimaging applications in living animals. We finally identify a novel composition (CaMgSi2O6:Eu 2+ ,Mn 2+ ,Pr 3+ ) for in vivo imaging, displaying a strong near-infrared afterglow centered on 685 nm, and present evidence that intravenous injection ofsuchpersistentluminescencenanoparticlesinmiceallowsnotonlyimprovedbuthighlysensitivedetectionthroughlivingtissues.

Controlling Electron Trap Depth To Enhance Optical Properties of Persistent Luminescence Nanoparticles for In Vivo Imaging ThomasMaldiney, † AurelieLecointre, ‡ BrunoViana,* ,‡ AurelieBessiere, ‡ MichelBessodes, † DidierGourier, ‡

Molecular persistently luminescent materials have received recent attention due to their promising applications in optical displays, biological imaging, chemical sensing, and security systems. In this review, we systematically summarize recent advances in establishing persistently luminescent materials—specifically focusing on materials composed of molecular hybrids for the first time. We describe the main strategies for synthesizing these hybrid materials, namely: (i) inorganics/organics, (ii) organics/organics, and (iii) organics/polymer systems and demonstrate how molecular hybrids provide synergistic effects, while improving luminescence lifetimes and efficiencies. These hybrid materials promote new methods for tuning key physical properties such as singlet–triplet excited state energies by controlling the chemical interactions and molecular orientations in the solid state. We review new advances in these materials from the perspective of examining experimental and theoretical approaches to room-temperature phosphorescence and thermally-activated delayed fluorescence. Finally, this review concludes by summarizing the current challenges and future opportunities for these hybrid materials.

Recent advances in persistent luminescence based on molecular hybrid materials

Flexible electromagnetic interference (EMI) shielding materials with excellent thermal conductivities and Joule heating performances are of urgent demand in the communication industry, artificial intelligence, and wearable electronics. In this work, highly conductive silver nanowires (AgNWs) were prepared using the polyol method. Cellulose sheets were then prepared by dissolving natural cotton in a green and efficient NaOH/urea aqueous solution. Finally, multifunctional flexible EMI shielding AgNWs/cellulose films were fabricated based on vacuum-assisted filtration and hot-pressing. AgNWs are evenly embedded in the inner cellulose matrix and overlap with each other to form a 3D network. AgNWs/cellulose films, with a thickness of 44.5 μm, obtain the superior EMI shielding effectiveness of 101 dB, which is the highest value ever reported for shielding materials with the same thickness. In addition, AgNWs/cellulose films present excellent tensile strength (60.7 MPa) and tensile modulus (3.35 GPa), ultrahigh electrical conductivity (σ, 5571 S/cm), and excellent in-plane thermal conductivity coefficient (λ∥, 10.55 W/mK), which can effectively dissipate the heat accumulation. Interestingly, AgNWs/cellulose films also show outstanding Joule heating performances, good stability, and sensitive temperature response at driving voltages, absolutely safe for the human body. Therefore, our fabricated multifunctional flexible AgNWs/cellulose films have broad prospects in the fields of EMI shielding and protection of outdoor large-scale power transformers and wearable electronics.

Multifunctional Flexible Electromagnetic Interference Shielding Silver Nanowires/Cellulose Films with Excellent Thermal Management and Joule Heating Performances.

Nanoporous two-dimensional materials are attractive for ionic and molecular nanofiltration but limited by insufficient mechanical strength over large areas. We report a large-area graphene-nanomesh/single-walled carbon nanotube (GNM/SWNT) hybrid membrane with excellent mechanical strength while fully capturing the merit of atomically thin membranes. The monolayer GNM features high-density, subnanometer pores for efficient transport of water molecules while blocking solute ions or molecules to enable size-selective separation. The SWNT network physically separates the GNM into microsized islands and acts as the microscopic framework to support the GNM, thus ensuring the structural integrity of the atomically thin GNM. The resulting GNM/SWNT membranes show high water permeance and a high rejection ratio for salt ions or organic molecules, and they retain stable separation performance in tubular modules.

Large-area graphene-nanomesh/carbon-nanotube hybrid membranes for ionic and molecular nanofiltration.

Persistent luminescence nanoprobes (PLNPs) can remain luminescent after ceasing excitation. Due to the ultra-long decay time of persistent luminescence (PersL), autofluorescence interference can be efficiently eliminated by collecting PersL signal after autofluorescence decays completely, thus the imaging contrast and sensing sensitivity can be significantly improved. Since near-infrared (NIR) light shows reduced scattering and absorption coefficient in penetrating biological organs or tissues, near-infrared persistent luminescence nanoprobes (NIR PLNPs) possess deep tissue penetration and offer a bright prospect in the areas of in vivo biosensing/bioimaging. In this review, we firstly summarize the design of different types of NIR PLNPs for biosensing/bioimaging, such as transition metal ions-doped NIR PLNPs, lanthanide ions-doped NIR PLNPs, organic molecules-based NIR PLNPs, and semiconducting polymer self-assembled NIR PLNPs. Notably, organic molecules-based NIR PLNPs and semiconductor self-assembled NIR PLNPs, for the first time, were introduced to the review of PLNPs. Secondly, the effects of different types of charge carriers on NIR PersL and luminescence decay of NIR PLNPs are significantly emphasized so as to build up an in-depth understanding of their luminescence mechanism. It includes the regulation of valence band and conduction band of different host materials, alteration of defect types, depth and concentration changes caused by ion doping, effective radiation transitions and energy transfer generated by different luminescence centers. Given the design and potential of NIR PLNPs as long-lived luminescent materials, the current challenges and future perspective in this rapidly growing field are also discussed.

Recent progress in engineering near-infrared persistent luminescence nanoprobes for time-resolved biosensing/bioimaging

Luminescent nanomaterials have attracted great attention in luminescence-based bioanalysis due to their abundant optical and tunable surface physicochemical properties. However, luminescent nanomaterials often suffer from serious autofluorescence and light scattering interference when applied to complex biological samples. Time-resolved luminescence methodology can efficiently eliminate autofluorescence and light scattering interference by collecting the luminescence signal of a long-lived probe after the background signals decays completely. Lanthanides have a unique [Xe]4fN electronic configuration and ladder-like energy states, which endow lanthanide-doped nanoparticles with many desirable optical properties, such as long luminescence lifetimes, large Stokes/anti-Stokes shifts, and sharp emission bands. Due to their long luminescence lifetimes, lanthanide-doped nanoparticles are widely used for high-sensitive biosensing and high-contrast bioimaging via time-resolved luminescence methodology. In this review, recent progress in the development of lanthanide-doped nanoparticles and their application in time-resolved biosensing and bioimaging are summarized. At the end of this review, the current challenges and perspectives of lanthanide-doped nanoparticles for time-resolved bioapplications are discussed.

Recent Progress in Time-Resolved Biosensing and Bioimaging Based on Lanthanide-Doped Nanoparticles.

Regulation of protein activity is essential for revealing the molecular mechanisms of biological processes. DNA and RNA achieve many uniquely efficient functions, such as genetic expression and regulation. The chemical capability to synthesize artificial nucleotides can expand the chemical space of nucleic acid libraries and further increase the functional diversity of nucleic acids. Herein, a versatile method has been developed for modular expansion of the chemical space of nucleic acid libraries, thus enabling the generation of aptamers able to regulate protein activity. Specifically, an aptamer that targets integrin alpha3 was identified and this aptamer can inhibit cell adhesion and migration. Overall, this chemical-design-assisted in vitro selection approach enables the generation of functional nucleic acids for elucidating the molecular basis of biological activities and uncovering a novel basis for the rational design of new protein-inhibitor pharmaceuticals.

Regulation of Protein Activity and Cellular Functions Mediated by Molecularly Evolved Nucleic Acids.

Bioactive metal ions play important roles in both physiological and pathological processes. Developing biosensing probes for bioactive metal ion detection can contribute to fields including disease diagnosis and therapy and studying the mechanisms of biological activities. In this work, we designed a dual-aptamer-conjugated molecular modulator that can detect Zn2+ and further inhibit Zn2+-induced amyloid β (Aβ) aggregation. The molecular modulator is able to selectively target Aβ species and block Zn2+ due to the specific recognition capability of aptamers. With the binding of Zn2+, the fluorescence signal of this molecular modulator is restored, thus allowing for Zn2+ detection. More importantly, this molecular modulator can inhibit the generation of Zn2+-triggered Aβ aggregates due to the trapping of Zn2+ around Aβ species. Circular dichroism measurements reveal that the dual-aptamer-conjugated molecular modulator prevents the conformational transition of the Aβ monomer from a random coil to a β-sheet. Furthermore, after treating with the molecular modulator, no Aβ aggregate is observed in the Aβ solution with added Zn2+, demonstrating that Aβ aggregation is successfully inhibited by this molecular modulator. Our approach provides a promising tool for detecting bioactive metal ions and studying the molecular mechanisms behind life activities.

Ling Liang

Papers

Large-area graphene-nanomesh/carbon-nanotube hybrid membranes for ionic and molecular nanofiltration.

Recent progress in engineering near-infrared persistent luminescence nanoprobes for time-resolved biosensing/bioimaging

Recent Progress in Time-Resolved Biosensing and Bioimaging Based on Lanthanide-Doped Nanoparticles.

Regulation of Protein Activity and Cellular Functions Mediated by Molecularly Evolved Nucleic Acids.

Dual-Aptamer-Conjugated Molecular Modulator for Detecting Bioactive Metal Ions and Inhibiting Metal-Mediated Protein Aggregation.