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We developed a simple, paper‐based device that enables sensitive detection by mass spectrometry (MS) without solid phase extraction or other sample preparation. Using glass fiber filter papers within a 3D printed holder, the device employs electrokinetic manipulations to stack, separate, and desalt charged molecules on paper prior to spray into the MS. Due to counter‐balanced electroosmotic flow and electrophoresis, charged analytes stack on the paper and desalting occurs in minutes. One end of the paper strip was cut into a sharp point and positioned near the inlet of a MS. The stacked analyte bands move toward the paper tip with the EOF where they are ionized by paper spray. The device was applied to analysis of PFAS in tap water with sub part‐per‐trillion detection limits in less than ten minutes with no sample pretreatment. Analysis of opioids in urine also occurs in minutes. The crucial parameters to enable stacking, separation, and MS ionization of both positively and negatively charged analytes were determined and optimized. Experimental and computational modeling studies confirm the electrokinetic stacking and analyte transport mechanisms. On‐paper separations were carried out by stacking analyte bands at different locations depending on their electrophoretic mobility, achieving baseline separation in some cases. [ABSTRACT FROM AUTHOR]

Without excess Li, anode‐free Li‐metal batteries (AFLMBs) have been proposed as the most likely solution to realizing highly‐safe and cost‐effective Li‐metal batteries. Nevertheless, short cyclic life puzzles conventional AFLMBs due to anodic dead Li accumulation with a local current concentration induced by irreversible electrolyte depletion, insufficient active Li reservoir and slow Li+ transfer at the solid electrolyte interphase (SEI). Herein, SrI2 is introduced into carbon paper (CP) current collector to effectively suppress dead Li through synergistic mechanisms including reversible I−/I3− redox reaction to reactivate dead Li, dielectric SEI surface with SrF2 and LiF to prevent electrolyte decomposition and highly ionic conductive (3.488 mS cm−1) inner layer of SEI with abundant LiI to enable efficient Li+ transfer inside. With the SrI2‐modified current collector, the NCM532/CP cell delivers unprecedented cyclic performances with a capacity of 129.2 mAh g−1 after 200 cycles. [ABSTRACT FROM AUTHOR]

Photocatalysis as one of the future environment technologies has been investigated for decades. Despite great efforts in catalyst engineering, the widely used powder dispersion and photoelectrode systems are still restricted by sluggish interfacial mass transfer and chemical processes. Here we develop a scalable bilayer paper from commercialized TiO2 and carbon nanomaterials, self‐supported at gas‐liquid‐solid interfaces for photothermal‐assisted triphase photocatalysis. The photogeneration of reactive oxygen species can be facilitated through fast oxygen diffusion over triphase interfaces, while the interfacial photothermal effect promotes the following free radical reaction for advanced oxidation of phenol. Under full spectrum irradiation, the triphase system shows 13 times higher reaction rate than diphase controlled system, achieving 88.4 % mineralization of high concentration phenol within 90 min full spectrum irradiation. The bilayer paper also exhibits high stability over 40 times cycling experiments and sunlight driven feasibility, showing potentials for large scale photocatalytic applications by being further integrated into a triphase flow reactor. [ABSTRACT FROM AUTHOR]

Accurate quantification of disease‐signature microRNAs (miRNAs) in biomedical samples is in high demand for clinical diagnosis but still challenging because of the low abundance of miRNAs and complicating interferences in the milieus. Here, we report a multi‐amplification strategy based on paper‐spray mass spectrometry (PS MS) for the analysis of miRNAs in blood. A toehold‐mediated DNA‐strand‐displacement reaction (TSD) is employed to amplify the signal chain and to ensure the specificity. The signal chain is then cleaved by UV light to release signal molecules for detection. Moreover, the paper spray method can efficiently filter out interfering substances in the blood and further enhance the sensitivity of detection. This concept is successfully demonstrated in the prototypical detection of the cancer biomarker miRNA‐141 in blood and serum. The proposed TSD‐PS MS approach provides an efficient method for the sensitive detection of oligonucleotides at low concentration in complicated milieus. [ABSTRACT FROM AUTHOR]

Two hybrid chloroantimonates(III), [Bzmim]3SbCl6 (1, Bzmim=1‐benzyl‐3‐methylimidazolium, Tm1=410 K) and [Bzmim]2SbCl5 (2, Tm2=348 K) are presented. 1 exhibits green emission (quantum efficiency of 87.5 %); 2 exhibits blue and red emissions under the irradiation of 310 and 396 nm light, respectively. Using different cooling methods, crystalline 1 and IL@2 (IL=ionic liquid of [Bzmim]Cl) could be generated from the molten 1. Reversible structural and PL transformation triggered by moisture or heat was observed between 1 and IL@2. Such PL switching, combined with the crystallization‐induced PL properties of 1 and 2, resulted in the firstly reported triple‐mode reversible PL switching, that is, on–off (T>Tm1), color switching (T

Pristine titanium dioxide (TiO2) changes color from white to black when it is reduced from TiIV to TiIII by photoexcited electrons. However, the black coloration requires substantial light energy to create, and it vanishes instantaneously upon exposure to air. This work reports the synthesis of surface‐functionalized N‐doped TiO2 nanocrystals that rapidly change color (i.e., within seconds) from whitish to black under low‐power irradiation with excellent color stability in atmospheric conditions. The N‐doping plays a critical role in promoting the surface‐adsorption of polyol groups to stabilize the TiIII species and accelerate the coloration process. A rewritable paper fabricated using these nanocrystals exhibits excellent writing and erasing reversibility in response to UV irradiation and oxygen exposure. The low‐cost, rapid response, excellent reversibility, and good color stability are vital advantages of N‐doped TiO2 nanocrystals for color‐switching applications. [ABSTRACT FROM AUTHOR]

We report herein a facile and generalized approach to the modification of solid surfaces with polymer brushes under ambient conditions: filter paper‐assisted surface‐initiated Cu0‐mediated controlled radical polymerization (PSI‐CuCRP). The polymerization solution wetted filter paper is sandwiched between a copper plate and an initiator‐modified substrate, which allows the creation of a surface‐initiated polymerization (SIP) "band‐aid" so that everyone can perform the surface grafting selectively with good control over the quality of the polymer brushes employing low concentration and microliter amounts of the monomer solution. The versatility of this method is demonstrated by grafting different homo‐, block‐, and multicomponent polymer brushes by using the same activation system and reaction conditions, the polymerization process can be precisely controlled to yield uniform polymers and show high chain‐end functionality which is exemplified by in situ tetra‐copolymerization. The combination of photolithography and paper cutting enables to prepare arbitrary three‐dimensional patterned polymer brushes on the surface. [ABSTRACT FROM AUTHOR]

Electrochemical aptamer‐based (E‐AB) sensors offer a powerful and general means for analyte detection in complex samples for various applications. Paper‐based E‐AB sensors could enable portable, low‐cost, and rapid detection of a broad range of targets, but it has proven challenging to fabricate suitable three‐electrode systems on paper. Here, we demonstrate a simple, economic, and environmentally friendly strategy for fabricating aptamer‐modified paper electrochemical devices (PEDs) via ambient vacuum filtration. The material, shape, size, and thickness of the three‐electrode PED system can be fully customized. We developed aptamer‐modified PEDs that enable sensitive and specific detection of small molecules in minimally processed biosamples. The sensitivity and stability of the PEDs are comparable to E‐AB sensors based on commercial gold electrodes. We believe our strategy can lead to the development of high performance PEDs for the on‐site detection of a variety of analytes. [ABSTRACT FROM AUTHOR]

Monitoring of human serum albumin (HSA) in a point‐of‐care fashion is urgently needed in particular for elderly or chronically ill patients. Herein, a dual‐state emissive chalcone probe having the feature of aggregation‐induced emission was designed and synthesized. The concentration of HSA can be evaluated by the ratios of emission from probes in aggregated and monomeric state, which gives a visually discernible red‐to‐green color change. A simple, portable paper‐based analytical device have been fabricated by integration of the recognition probe in the detection pad and employed for HSA test using the whole blood samples. This paper‐based assay shows the analytical capability comparable to the standard testing methods but is in a point‐of‐care fashion, providing a promising tool for at‐home HSA detection and HSA‐related disease diagnosis. [ABSTRACT FROM AUTHOR]

The reliable detection of pathogenic bacteria in complex biological samples using simple assays or devices remains a major challenge. Herein, we report a simple colorimetric paper device capable of providing specific and sensitive detection of Helicobacter pylori (H. pylori), a pathogen strongly linked to gastric carcinoma, gastric ulcers, and duodenal ulcers, in stool samples. The sensor molecule, an RNA‐cleaving DNAzyme obtained through in vitro selection, is activated by a protein biomarker from H. pylori. The colorimetric paper sensor, designed on the basis of the RNA‐cleaving property of the DNAzyme, is capable of sensitive detection of H. pylori in human stool samples with minimal sample processing and provides results in minutes. It remains fully functional under storage at ambient temperature for at least 130 days. This work lays a foundation for developing DNAzyme‐enabled paper‐based point‐of‐care diagnostic devices for monitoring pathogens in complex samples. [ABSTRACT FROM AUTHOR]

We report the unprecedented electrocatalytic activity of a series of molecular nickel thiolate complexes (1–5) in reducing CO2 to C1–3 hydrocarbons on carbon paper in pH‐neutral aqueous solutions. Ni(mpo)2 (3, mpo=2‐mercaptopyridyl‐N‐oxide), Ni(pyS)3− (4, pyS=2‐mercaptopyridine), and Ni(mp)2− (5, mp=2‐mercaptophenolate) were found to generate C3 products from CO2 for the first time in molecular complex. Compound 5 exhibits Faradaic efficiencies (FEs) of 10.6 %, 7.2 %, 8.2 % for C1, C2, C3 hydrocarbons respectively at −1.0 V versus the reversible hydrogen electrode. Addition of CO to the system significantly promotes the FEC1–C3 to 41.1 %, suggesting that a key Ni−CO intermediate is associated with catalysis. A variety of spectroscopies have been performed to show that the structures of nickel complexes remain intact during CO2 reduction. [ABSTRACT FROM AUTHOR]

This work reports on fully integrated "sample‐in‐signal‐out" microfluidic paper‐based analytical devices (μPADs) relying on bioluminescence resonance energy transfer (BRET) switches for analyte recognition and colorimetric signal generation. The devices use BRET‐based antibody sensing proteins integrated into vertically assembled layers of functionalized paper, and their design enables sample volume‐independent and fully reagent‐free operation, including on‐device blood plasma separation. User operation is limited to the application of a single drop (20–30 μL) of sample (serum, whole blood) and the acquisition of a photograph 20 min after sample introduction, with no requirement for precise pipetting, liquid handling, or analytical equipment except for a camera. Simultaneous detection of three different antibodies (anti‐HIV1, anti‐HA, and anti‐DEN1) in whole blood was achieved. Given its simplicity, this type of device is ideally suited for user‐friendly point‐of‐care testing in low‐resource environments. A single drop of blood on paper: Bioluminescent sensing proteins integrated into a multi‐layer paper‐based device allow the user‐friendly and simple quantification of monoclonal antibodies from a single drop of blood by simple color change monitoring. [ABSTRACT FROM AUTHOR]

Abstract: Micrometer‐sized functional nucleic acid (FNA) superstructures (denoted as 3D DNA) were examined as a unique class of biorecognition elements to produce highly functional bioactive paper surfaces. 3D DNA containing repeating sequences of either a DNA aptamer or DNAzyme was created from long‐chain products of rolling circle amplification followed by salt aging. The resulting 3D DNA retained its original spherical shape upon inkjet printing and adhered strongly to the paper surface via physisorption. 3D DNA paper sensors showed resistance to degradation by nucleases, suppressed nonspecific protein adsorption, and provided a much higher surface density of functional DNA relative to monomeric FNAs, making such species ideally suited for development of paper‐based biosensors. [ABSTRACT FROM AUTHOR]

Abstract: A potentially universal approach is presented for enzyme attachment to cellulose that significantly enhances enzyme stability while retaining high activity, and involves no chemical functionalization of cellulose. Bovine serum albumin (BSA) was interlocked in cellulose to form a protein‐friendly surface (named BSA‐Paper), while also providing COOH and NH2 groups for subsequent attachment of enzymes. The desired enzyme is then mixed with additional BSA and interlocked on BSA‐Paper. The second BSA layer dilutes and crosslinks the enzyme for improved stability. Laccase was tested as a model enzyme for interlocking on BSA‐Paper, and was found to retain over 100 % activity and was 240 times more stable at 25 °C (half life=180 d) than laccase. This new approach was also tested with a few other enzymes with encouraging results, thus providing a potentially universal method for stabilization of enzymes on cellulose with retention of high activities. [ABSTRACT FROM AUTHOR]

A general anion-sensing platform is reported based on a portable and cost-effective ion-selective optode and a smartphone detector equipped with a color analysis app. In contrast to traditional anion-selective optodes using a hydrophobic polymer and/or plasticizer to dissolve hydrophobic sensing elements, the new optode relies on hydrophilic cellulose paper. The anion ionophore and a lipophilic pH indicator are inkjet-printed and adsorbed on paper and form a 'dry' hydrophobic sensing layer. Porous cellulose sheets also allow the sensing site to be modified with dried buffer that prevents any sample pH dependence of the observed color change. A highly selective fluoride optode using an AlIII-porphyrin ionophore is examined as an initial example of this new anion sensing platform for measurements of fluoride levels in drinking water samples. Apart from Lewis acid-base recognition, hydrogen bonding recognition is also compatible with this sensing platform. [ABSTRACT FROM AUTHOR]

A new approach exploiting the dual properties of thiol-grafted cellulose paper for promoting copper-catalyzed [3+2]-cycloadditions of organic azides with alkynes and adsorbing residual copper species in solution was developed. The thiol-grafted cellulose paper, used as a paper strip, effects the reduction of CuII to catalytically active CuI and acts as a powerful adsorbent for copper, thereby facilitating the work-up process and leaving the crude mixture almost free of copper residues after a single filtration. [ABSTRACT FROM AUTHOR]

Abstract: We report a paper‐based aptasensor platform that uses two reaction zones and a connecting bridge along with printed multifunctional bio/nano materials to achieve molecular recognition and signal amplification. Upon addition of analyte to the first zone, a fluorescently labelled DNA or RNA aptamer is desorbed from printed graphene oxide, rapidly producing an initial fluorescence signal. The released aptamer then flows to the second zone where it reacts with printed reagents to initiate rolling circle amplification, generating DNA amplicons containing a peroxidase‐mimicking DNAzyme, which produces a colorimetric readout that can be read in an equipment‐free manner or with a smartphone. The sensor was demonstrated using an RNA aptamer for adenosine triphosphate (a bacterial marker) and a DNA aptamer for glutamate dehydrogenase (Clostridium difficile marker) with excellent sensitivity and specificity. These targets could be detected in spiked serum or feacal samples, demonstrating the potential for testing clinical samples. [ABSTRACT FROM AUTHOR]

A single-step laser scribing process is used to pattern nanostructured electrodes on paper-based devices. The facile and low-cost technique eliminates the need for chemical reagents or controlled conditions. This process involves the use of a CO2 laser to pyrolyze the surface of the paperboard, producing a conductive porous non-graphitizing carbon material composed of graphene sheets and composites with aluminosilicate nanoparticles. The new electrode material was extensively characterized, and it exhibits high conductivity and an enhanced active/geometric area ratio; it is thus well-suited for electrochemical purposes. As a proof-of-concept, the devices were successfully employed for different analytical applications in the clinical, pharmaceutical, food, and forensic fields. The scalable and green fabrication method associated with the features of the new material is highly promising for the development of portable electrochemical devices. [ABSTRACT FROM AUTHOR]

We present a self-assembled template that consists of tetraphenylmethane derivatives and adopts a periodic lateral arrangement on a Au(111) surface with acetyl groups sticking out of the molecular film. By using the tip of a scanning tunneling microscope, these acetyl groups can be removed in a spatially controlled way without significantly affecting the remaining molecular assembly. The chemically modified molecules can be readily distinguished from the original ones such that information can be engraved in the molecular film. Both the modified nature of an individual molecule and the order of the molecular film are shown to persist at room temperature. The mesh size of this molecular graph paper can be tuned by varying the length of the molecular spacer so that writing and reading information on the nanoscale with variable letter sizes becomes possible. [ABSTRACT FROM AUTHOR]

Current paper-based potentiometric ion-sensing platforms are planar devices used for clinically relevant ions. These devices, however, have not been designed for the potentiometric biosensing of proteins or small molecule analytes. A three-dimensional origami paper-based device, in which a solid-contact ion-selective electrode is integrated with an all-solid-state reference electrode, is described for the first time. The device is made by impregnation of paper with appropriate bioreceptors and reporting reagents on different zones. By folding and unfolding the paper structures, versatile potentiometric bioassays can be performed. A USB-controlled miniaturized electrochemical detector can be used for simple and in situ measurements. Using butyrylcholinesterase as a model enzyme, the device has been successfully applied to the detection of enzyme activities and organophosphate pesticides involved in the enzymatic system as inhibitors. The proposed 3D origami paper device allows the potentiometric biosensing of proteins and small molecules in a simple, portable, and cost-effective way. [ABSTRACT FROM AUTHOR]

We report on a paper device capable of carrying out target-induced rolling circle amplification (RCA) to produce massive DNA amplicons that can be easily visualized. Interestingly, we observed that RCA was more proficient on paper than in solution, which we attribute to a significantly higher localized concentration of immobilized DNA. Furthermore, we have successfully engineered a fully functional paper device for sensitive DNA or microRNA detection via printing of all RCA-enabling molecules within a polymeric sugar film formed from pullulan, which was integrated with the paper device. This encapsulation not only stabilizes the entrapped reagents at room temperature but also enables colorimetric bioassays with minimal steps. [ABSTRACT FROM AUTHOR]

We have developed nanoparticle-embedded paper-spray mass spectrometry for studying three types of heterogeneously catalyzed reactions: 1) Palladium-nanoparticle-catalyzed Suzuki cross-coupling reactions, 2) palladium- or silver-nanoparticle-catalyzed 4-nitrophenol reduction, and 3) gold-nanoparticle-catalyzed glucose oxidation. These reactions were almost instantaneous on the nanocatalyst-embedded paper, which subsequently transferred the transient intermediates and products to a mass spectrometer for their detection. This in situ method of capturing transient intermediates and products from heterogeneous catalysis is highly promising for investigating the mechanism of catalysis and rapidly screening catalytic activity under ambient conditions. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance (AMR), the ability of a bacterial species to resist the action of an antimicrobial drug, has been on the rise due to the widespread use of antimicrobial agents. Per the World Health Organization, AMR has an estimated annual cost of USD 34 billion in the US and is predicted to be the number one cause of death worldwide by 2050. One way AMR bacteria can spread, and by which individuals can contract AMR infections, is through contaminated water. Monitoring AMR bacteria in the environment currently requires that samples be transported to a central laboratory for slow and labor intensive tests. We have developed an inexpensive assay using paper-based analytical devices (PADs) that can test for the presence of β-lactamase-mediated resistance. To demonstrate viability, the PAD was used to detect β-lactam resistance in wastewater and sewage and identified resistance in individual bacterial species isolated from environmental water sources. [ABSTRACT FROM AUTHOR]

We demonstrate, for the first time, the multiplexed determination of microbial species from whole blood using the paper-folding technique of origami to enable the sequential steps of DNA extraction, loop-mediated isothermal amplification (LAMP), and array-based fluorescence detection. A low-cost handheld flashlight reveals the presence of the final DNA amplicon to the naked eye, providing a 'sample-to-answer' diagnosis from a finger-prick volume of human blood, within 45 min, with minimal user intervention. To demonstrate the method, we showed the identification of three species of Plasmodium, analyzing 80 patient samples benchmarked against the gold-standard polymerase chain reaction (PCR) assay in an operator-blinded study. We also show that the test retains its diagnostic accuracy when using stored or fixed reference samples. [ABSTRACT FROM AUTHOR]

Phage display biopanning is used to identify peptides that show material-selective adsorption, effectively distinguishing between the cellulose of paper and the printed toner of standard office laser printers. These genetically selected 12mer peptides can selectively coat either non-printed cellulose or printed toner patterns. Furthermore, triazolindione ligation chemistry is exploited to introduce, for example, dyes or functional peptides selectively to the coatings. The strategy offers an easy access towards the patterned functionalization of paper-based materials, which potentially is of relevance for low-cost diagnostics or biomedical devices. [ABSTRACT FROM AUTHOR]

Current methods of monitoring breathing require cumbersome, inconvenient, and often expensive devices; this requirement sets practical limitations on the frequency and duration of measurements. This article describes a paper-based moisture sensor that uses the hygroscopic character of paper (i.e. the ability of paper to adsorb water reversibly from the surrounding environment) to measure patterns and rate of respiration by converting the changes in humidity caused by cycles of inhalation and exhalation to electrical signals. The changing level of humidity that occurs in a cycle causes a corresponding change in the ionic conductivity of the sensor, which can be measured electrically. By combining the paper sensor with conventional electronics, data concerning respiration can be transmitted to a nearby smartphone or tablet computer for post-processing, and subsequently to a cloud server. This means of sensing provides a new, practical method of recording and analyzing patterns of breathing. [ABSTRACT FROM AUTHOR]

Ion-selective electrodes (ISEs) are widely used tools for fast and accurate ion sensing. Herein their design is simplified by embedding a potentiometric cell into paper, complete with an ISE, a reference electrode, and a paper-based microfluidic sample zone that offer the full function of a conventional ISE setup. The disposable planar paper-based ion-sensing platform is suitable for low-cost point-of-care and in-field testing applications. The design is symmetrical and each interfacial potential within the cell is well defined and reproducible, so that the response of the device can be theoretically predicted. For a demonstration of clinical applications, paper-based Cl− and K+ sensors are fabricated with highly reproducible and linear responses towards different concentrations of analyte ions in aqueous and biological samples. The single-use devices can be fabricated by a scalable method, do not need any pretreatment prior to use, and only require a sample volume of 20 μL. [ABSTRACT FROM AUTHOR]

Controlled modulation of electronic and magnetic properties in stimuli‐responsive materials provides valuable insights for the design of magnetoelectric or multiferroic devices. This paper demonstrates the modulation of electrical and magnetic properties of a semiconductive, paramagnetic metal−organic framework (MOF) Cu3(C6O6)2 with small gaseous molecules, NH3, H2S, and NO. This study merges chemiresistive and magnetic tests to reveal that the MOF undergoes simultaneous changes in electrical conductance and magnetization that are uniquely modulated by each gas. The features of response, including direction, magnitude, and kinetics, are modulated by the physicochemical properties of the gaseous molecules. This study advances the design of multifunctional materials capable of undergoing simultaneous changes in electrical and magnetic properties in response to chemical stimuli. [ABSTRACT FROM AUTHOR]

In this paper, we proposed a heteroatom substitution strategy (HSS) in the δ‐valerolactone (VL) system to modulate thermodynamics toward chemically recyclable polyesters. Three VL‐based monomers containing different heteroatoms (M1 (N), M2 (S), and M3 (O)), instead of C‐5 carbon, were designed and synthesized to verify our proposed HSS. All three monomers undergo organocatalytic living/controlled ROP and controllable depolymerization. Impressively, the resulting P(M1) achieved over 99 % monomer recovery under both mild solution depolymerization and high vacuum pyrolysis conditions without any side reactions, and the recycled monomers can be polymerized again forming new polymers. The systematic study of the relationship between heteroatom substitution and recyclability shows that introducing heteroatoms does change the thermodynamics of the monomers (ΔHpo, ΔSpo and Tc values), thereby adjusting the polymerizability and depolymerizability. DFT calculations found that the introduction of heteroatoms adjusts the ring strain by changing the angular strain of the monomers, and the order of their angular strain (M2>M1>M3) is consistent with the order of the experimentally obtained enthalpy change. Notably, the one‐pot/one‐step copolymerization of two of each of the three monomers enables the synthesis of sequence‐controlled copolymers from gradient to random to block structures, by simply switching the copolymerization temperature. [ABSTRACT FROM AUTHOR]

The paper aims to elucidate the final stages in the biosynthesis of the [2Fe]H active site of the [FeFe]‐hydrogenases. The recently hypothesized intermediate [Fe2(SCH2NH2)2(CN)2(CO)4]2− ([1]2−) was prepared by a multistep route from [Fe2(S2)(CN)(CO)5]−. The following synthetic intermediates were characterized in order: [Fe2(SCH2NHFmoc)2(CNBEt3)(CO)5]−, [Fe2(SCH2NHFmoc)2(CN)−(CO)5]−, and [Fe2(SCH2NHFmoc)2(CN)2(CO)4]2−, where Fmoc is fluorenylmethoxycarbonyl). Derivatives of these anions include [K(18‐crown‐6)]+, PPh4+ and PPN+ salts as well as the 13CD2‐isotopologues. These Fe2 species exist as a mixture of two isomers attributed to diequatorial (ee) and axial‐equatorial (ae) stereochemistry at sulfur. In vitro experiments demonstrate that [1]2− maturates HydA1 in the presence of HydF and a cocktail of reagents. HydA1 can also be maturated using a highly simplified cocktail, omitting HydF and other proteins. This result is consistent with HydA1 participating in the maturation process and refines the roles of HydF. [ABSTRACT FROM AUTHOR]

The artificial microenvironments inside coordination cages have gained significant attention for performing enzyme‐like catalytic reactions by facilitating the formation of labile and complex molecules through a "ship‐in‐a‐bottle" approach. Despite many fascinating examples, this approach remains scarcely explored in the context of synthesizing metallic clusters such as polyoxometalates (POMs). The development of innovative approaches to control and influence the speciation of POMs in aqueous solutions would greatly advance their applicability and could ultimately lead to the formation of elusive clusters that cannot be synthesized by using traditional methods. In this study, we employ host–guest stabilization within a coordination cage to enable a novel cavity‐directed synthesis of labile POMs in aqueous solutions under mild conditions. The elusive Lindqvist [M6O19]2− (M=Mo or W) POMs were successfully synthesized at room temperature via the condensation of molybdate or tungstate building blocks within the confined cavity of a robust and water‐soluble Pt6L4(NO3)12 coordination cage. Importantly, the encapsulation of these POMs enhances their stability in water, rendering them efficient catalysts for environmentally friendly and selective sulfoxidation reactions using H2O2 as a green oxidant in a pure aqueous medium. The approach developed in this paper offers a means to synthesize and stabilize the otherwise unstable metal‐oxo clusters in water, which can broaden the scope of their applications. [ABSTRACT FROM AUTHOR]

The introduction of nitrogen‐containing functional groups to chiral polymer backbones enables the tailoring of physical properties and offers opportunities for further post‐polymerization modification. However, the substrate scope of such polymers is extremely limited because monomers having nitrogen‐containing groups can change coordination state with respect to the metal centers, thus decreasing the activity and enantioselectivity and even poisoning the catalyst completely. In this paper, we report our attempts to carry out the asymmetric copolymerization of meso‐epoxide with highly reactive isocyanates. In particular, we found that biphenol‐linked bimetallic Co(III) complexes with multiple chiral centers are very efficient in catalyzing this asymmetric copolymerization reaction, affording optically active polyurethanes with a completely alternating nature and a high enantioselectivity of up to 94 % ee. Crucially, we identified that the steric hindrance at the phenolate ortho position of the ligand strongly influences the catalytic activity and product enantioselectivity. In addition, density functional theory calculations revealed that the highly sterically bulky substituents change the mechanism from bimetallic to monometallic, and result in the unexpected inversion of the chiral induction direction. Moreover, the high stereoregularity of the produced polyurethanes enhances their thermal stability, and they can be selectively decomposed into oxazolidinones. This study offers a versatile methodology for the synthesis of chiral polymers containing nitrogen functionalities. [ABSTRACT FROM AUTHOR]

Green production of NH3, especially the Li‐mediated electrochemical N2 reduction reaction (NRR) in non‐aqueous solutions, is attracting research interest. Controversies regarding the NRR mechanism greatly impede its optimization and wide applications. To understand the electrocatalytic process, we treated Au coated carbon fibrous paper (Au/CP) as the model catalyst. In situ XRD confirmed the transformation of lithium intermediates during NRR. Au greatly improved electron transfer kinetics to catalyze metallic Li formation, and accordingly highly accelerated spontaneous NRR. The Faradaic efficiency of NRR on Au/CP reached 34.0 %, and NH3 yield was as high as 50 μg h−1 cm−2. Our research shows that the key step of Li‐mediated non‐aqueous NRR is electrocatalytic Li reduction and offers a novel electrocatalyst design method for Li reduction. [ABSTRACT FROM AUTHOR]

Aliphatic polycarbonates (aPCs) have become increasingly popular as functional materials due to their biocompatibility and capacity for on‐demand degradation. Advances in polymerization techniques and the introduction of new functional monomers have expanded the library of aPCs available, offering a diverse range of chemical compositions and structures. To accommodate the emerging requirements of new applications in biomedical and energy‐related fields, various manufacturing techniques have been adopted for processing aPC‐based materials. However, a summary of these techniques has yet to be conducted. The aim of this paper is to enrich the toolbox available to researchers, enabling them to select the most suitable technique for their materials. In this paper, a concise review of the recent progress in processing techniques, including controlled self‐assembly, electrospinning, additive manufacturing, and other techniques, is presented. We also highlight the specific challenges and opportunities for the sustainable growth of this research area and the successful integration of aPCs in industrial applications. [ABSTRACT FROM AUTHOR]

We report a simple approach based on a chemical reduction method to synthesize aqueous inorganic ink comprised of hexagonal MnO2 nanosheets. The MnO2 ink exhibits long-term stability and continuous thin films can be formed on various substrates without using any binder. To obtain a flexible electrode for capacitive energy storage, the MnO2 ink was printed onto commercially available A4 paper pretreated with multiwalled carbon nanotubes. The electrode exhibited a maximum specific capacitance of 1035 F g−1 (91.7 mF cm−2). Paper-based symmetric and asymmetric capacitors were assembled, which gave a maximum specific energy density of 25.3 Wh kg−1 and a power density of 81 kW kg−1. The device could maintain a 98.9 % capacitance retention over 10 000 cycles at 4 A g−1. The MnO2 ink could be a versatile candidate for large-scale production of flexible and printable electronic devices for energy storage and conversion. [ABSTRACT FROM AUTHOR]

Rapid, precise, and reproducible deposition of a broad variety of functional materials, including analytical assay reagents and biomolecules, has made inkjet printing an effective tool for the fabrication of microanalytical devices. A ubiquitous office device as simple as a standard desktop printer with its multiple ink cartridges can be used for this purpose. This Review discusses the combination of inkjet printing technology with paper as a printing substrate for the fabrication of microfluidic paper-based analytical devices (μPADs), which have developed into a fast-growing new field in analytical chemistry. After introducing the fundamentals of μPADs and inkjet printing, it touches on topics such as the microfluidic patterning of paper, tailored arrangement of materials, and functionalities achievable exclusively by the inkjet deposition of analytical assay components, before concluding with an outlook on future perspectives. [ABSTRACT FROM AUTHOR]

A simple method is described for the patterned deposition of Teflon on paper to create an integrated platform for parallel organic synthesis and cell-based assays. Solvent-repelling barriers made of Teflon-impregnated paper confine organic solvents to specific zones of the patterned array and allow for 96 parallel flow-through syntheses on paper. The confinement and flow-through mixing significantly improves the peptide yield and simplifies the automation of this synthesis. The synthesis of 100 peptides ranging from 7 to 14 amino acids in length gave over 60 % purity for the majority of the peptides (>95 % yield per coupling/deprotection cycle). The resulting peptide arrays were used in cell-based screening to identify 14 potent bioactive peptides that support the adhesion or proliferation of breast cancer cells in a 3D environment. In the future, this technology could be used for the screening of more complex phenotypic responses, such as cell migration or differentiation. [ABSTRACT FROM AUTHOR]

Flexible non-metal oxygen electrodes fabricated from phosphorus-doped graphitic carbon nitride nano-flowers directly grown on carbon-fiber paper exhibit high activity and stability in reversibly catalyzing oxygen reduction and evolution reactions, which is a result of N, P dual action, enhanced mass/charge transfer, and high active surface area. The performance is comparable to that of the state-of-the-art transition-metal, noble-metal, and non-metal catalysts. Remarkably, the flexible nature of these oxygen electrodes allows their use in folded and rolled-up forms, and directly as cathodes in Zn-air batteries, featuring low charge/discharge overpotential and long lifetime. [ABSTRACT FROM AUTHOR]

Ambient ionization is achieved by spraying from a carbon nanotube (CNT)-impregnated paper surface under the influence of small voltages (≥3 V). Organic molecules give simple high-quality mass spectra without fragmentation in the positive or negative ion modes. Conventional field ionization is ruled out, and it appears that field emission of microdroplets occurs. Microscopic examination of the CNT paper confirms that the nanoscale features at the paper surface are responsible for the high electric fields. Raman spectra imply substantial current flows in the nanotubes. The performance of this analytical method was demonstrated for a range of volatile and nonvolatile compounds and a variety of matrices. [ABSTRACT FROM AUTHOR]

A straightforward photo-annealing approach was developed for building functional polymer layers on paper. Conducting polyaniline with the ability for photothermal conversion can be readily annealed by near-infrared light. The annealed polymers become both insulating and hydrophobic. Selective photo-annealing produces a functional layer with patterned conductive arrays. This material exhibits real-time response to ammonium gas. Complete photo-annealing preserves the porous structure but changes the wettability of the polyaniline-nanofiber film. [ABSTRACT FROM AUTHOR]

Light to wear: Aluminum coated fibrous materials with excellent electrical conductivity and mechanical endurance are fabricated at room temperature by a chemical solution process. The resulting aluminum‐coated conductive papers and threads can be used in electric circuits for flexible and wearable electronics. [ABSTRACT FROM AUTHOR]

Plating battery electrodes typically deliver higher specific capacity values than insertion or conversion electrodes because the ion charge carriers represent the sole electrode active mass, and a host electrode is unnecessary. However, reversible plating electrodes are rare for electronically insulating nonmetals. Now, a highly reversible iodine plating cathode is presented that operates on the redox couples of I2/[ZnIx(OH2)4−x]2−x in a water‐in‐salt electrolyte. The iodine plating cathode with the theoretical capacity of 211 mAh g−1 plates on carbon fiber paper as the current collector, delivering a large areal capacity of 4 mAh cm−2. Tunable femtosecond stimulated Raman spectroscopy coupled with DFT calculations elucidate a series of [ZnIx(OH2)4−x]2−x superhalide ions serving as iodide vehicles in the electrolyte, which eliminates most free iodide ions, thus preventing the consequent dissolution of the cathode‐plated iodine as triiodides. [ABSTRACT FROM AUTHOR]

Two‐dimensional (2D) layered materials demonstrate prominent advantage in regulating lithium plating/stripping behavior by confining lithium diffusion/plating within interlayer gaps. However, achieving effective interlayer confined lithium diffusion/plating without compromising the stability of bulk‐structural and the solid electrolyte interphase (SEI) remains a considerable challenge. This paper presents an electrochemical scissor and lithium zipper‐driven protocol for realizing interlayer confined lithium plating with pretty‐low strain and volume change. In this protocol, lithium serves as a "zipper" to reunite the adjacent MXene back to MAX‐like phase to markedly enhance the structural stability, and a lithium halide‐rich SEI is formed by electrochemically removing the terminals of halogenated MXenes to maintain the stability and rapid lithium ions diffusion of SEI. When the Ti3C2I2 serves as the host for lithium plating, the average coulomb efficiency exceeds 97.0 % after 320 lithium plating/stripping cycles in conventional ester electrolyte. Furthermore, a full cell comprising of LiNi0.8Mn0.1Co0.1O2 and Ti3C2I2@Li exhibits a capacity retention rate of 73.4 % after 200 cycles even under high cathode mass‐loading (20 mg cm−2) and a low negative/positive capacity ratio of 1.4. Our findings advance the understanding of interlayer confined lithium plating in 2D layered materials and provide a new direction in regulating lithium and other metal plating/stripping behaviors. [ABSTRACT FROM AUTHOR]

Machine learning is increasingly integrated into chemistry research by guiding experimental procedures, correlating structure and function, interpreting large experimental datasets, to distill scientific insights that might be challenging with traditional methods. Such applications, however, largely focus on gaining insights via big data and/or big computation, while neglecting the valuable chemical prior knowledge dwelling in chemists' minds. In this paper, we introduce an Electrochemistry‐Informed Neural Network (ECINN) by explicitly embedding electrochemistry priors including the Butler–Volmer (BV), Nernst and diffusion equations on the backbone of neural networks for multi‐task discovery of electrochemistry parameters. We applied the ECINN to voltammetry experiments of Fe2+/Fe3+ ${{\rm F}{{\rm e}}^{2+}/{\rm F}{{\rm e}}^{3+}}$ and RuNH362+/RuNH363+ ${{\rm R}{\rm u}{\left({\rm N}{{\rm H}}_{3}\right)}_{6}^{2+{\rm \ }}/{\rm R}{\rm u}{\left({\rm N}{{\rm H}}_{3}\right)}_{6}^{3+{\rm \ }}}$ redox couples to discover electrode kinetics and mass transport parameters. Notably, ECINN seamlessly integrated mass transport with BV to analyze the entire voltammogram to infer transfer coefficients directly, so offering a new approach to Tafel analysis by outdating various mass transport correction methods. In addition, ECINN can help discover the nature of electron transfer and is shown to refute incorrect physics if imposed. This work encourages chemists to embed their domain knowledge into machine learning models to start a new paradigm of chemistry‐informed machine learning for better accountability, interpretability, and generalization. [ABSTRACT FROM AUTHOR]

Benzo‐fused nitrogen heterocycles are common features of bioactive molecules, and the enantioselective synthesis of their substituted analogues is an important goal. In this paper we demonstrate a practical and mechanistically intriguing approach to the enantioselective synthesis of 1‐arylbenzazepines and their analogues. The reaction sequence starts with an asymmetric migratory ring expansion of indoline, tetrahydroquinoline, or tetrahydrobenzazepine ureas on treatment with a chiral lithium amide base. Treatment of the ring‐expanded ureas with acid triggers a two‐atom ring contraction—an 'azatropic shift' in which one urea nitrogen displaces the other—with almost complete retention of stereochemistry. Aminolysis of the urea products provides enantioenriched 1‐aryl‐tetrahydrobenzazepine derivatives and their congeners, including an analogue of an intermediate in the synthesis of the drug solifenacin. Deuteration, in situ IR, and DFT studies provide evidence for the mechanisms of the reaction steps. [ABSTRACT FROM AUTHOR]

The implementation of supported metal catalysts heavily relies on the synergistic interactions between metal nanoparticles and the material they are dispersed on. It is clear that interfacial perimeter sites have outstanding skills for turning catalytic reactions over, however, high activity and selectivity of the designed interface‐induced metal distortion can also obtain catalysts for the most crucial industrial processes as evidenced in this paper. Herein, the beneficial synergy established between designed Pt nanoparticles and MnO in the course of the reverse water gas shift (RWGS) reaction resulted in a Pt/MnO catalyst having ≈10 times higher activity compared to the reference Pt/SBA‐15 catalyst with >99 % CO selectivity. Under activation, a crystal assembly through the metallic Pt (110) and MnO evolved, where the plane distance differences caused a mismatched‐row structure in softer Pt nanoparticles, which was identified by microscopic and surface‐sensitive spectroscopic characterizations combined with density functional theory simulations. The generated edge dislocations caused the Pt lattice expansion which led to the weakening of the Pt−CO bond. Even though MnO also exhibited an adverse effect on Pt by lowering the number of exposed metal sites, rapid desorption of the linearly adsorbed CO species governed the performance of the Pt/MnO in the RWGS. [ABSTRACT FROM AUTHOR]

Disaccharides are composed of two monosaccharide subunits joined by a glycosidic linkage in an α or β configuration. Different combinations of isomeric monosaccharide subunits and different glycosidic linkages result in different isomeric disaccharide products. Thus, direct discrimination of these disaccharide isomers from a mixture is extremely difficult. In this paper, a hetero‐octameric Mycobacterium smegmatis porin A (MspA) nanopore conjugated with a phenylboronic acid (PBA) adapter was applied for disaccharide sensing, with which three most widely known disaccharides in nature, including sucrose, lactose and maltose, were clearly discriminated. Besides, all six isomeric α‐D‐glucopyranosyl‐D‐fructoses, differing only in their glycosidic linkages, were also well resolved. Assisted by a custom machine learning algorithm, a 0.99 discrimination accuracy is achieved. Nanopore discrimination of disaccharide isomers with different glycosidic linkages, which has never been previously demonstrated, is inspiring for nanopore saccharide sequencing. This sensing capacity was also applied in direct identification of isomaltulose additives in a commercial sucrose‐free yogurt, from which isomaltulose, lactose and L‐lactic acid were simultaneously detected. [ABSTRACT FROM AUTHOR]

This paper presents a Mn(I)‐catalysed methodology for the enantioselective hydrophosphination of terminal alkenyl aza‐heteroarenes. The catalyst operates through H−P bond activation, enabling successful hydrophosphination of a diverse range of alkenyl‐heteroarenes with high enantioselectivity. The presented protocol addresses the inherently low reactivity and the commonly encountered suboptimal enantioselectivities of these challenging substrates. As an important application we show that this method facilitates the synthesis of a non‐symmetric tridentate P,N,P‐containing ligand like structure in just two synthetic steps using a single catalytic system. [ABSTRACT FROM AUTHOR]

It is shown that data presented in a paper by Chao and co‐workers do not support the formation of active “Carbon Radicals” as claimed according to the title. The assignments of observed ESR spectra and the mechanistic interpretation are severely flawed. Hence, other reactive intermediates must be responsible for the observed tumor‐damaging effects. [ABSTRACT FROM AUTHOR]

In this paper, we report BF3 ⋅ OEt2 as a catalyst to shuttle equivalents of HF from a fluoroalkane to an alkyne. Reactions of terminal and internal aliphatic alkynes led to formation of difluoroalkane products, while diarylalkynes can be selectively converted into fluoroalkenes. The method tolerates numerous sensitive functional groups including halogen, protected amine, ester and thiophene substituents. Mechanistic studies (DFT, probe experiments) suggest the catalyst is involved in both the defluorination and fluorination steps, with BF3 acting as a Lewis acid and OEt2 a weak Lewis base that mediates proton transfer. In certain cases, the interconversion of fluoroalkene and difluoroalkane products was found to be reversible. The new catalytic system was applied to demonstrate proof‐of‐concept recycling of poly(vinylidene difluoride). [ABSTRACT FROM AUTHOR]