Efficient learning of mixed-state tomography for photonic quantum walk.

Noise-enhanced applications in open quantum walk (QW) has recently seen a surge due to their ability to improve performance. However, verifying the success of open QW is challenging, as mixed-state tomography is a resource-intensive process, and implementing all required measurements is almost impossible due to various physical constraints. To address this challenge, we present a neural-network-based method for reconstructing mixed states with a high fidelity (∼97.5%) while costing only 50% of the number of measurements typically required for open discrete-time QW in one dimension. Our method uses a neural density operator that models the system and environment, followed by a generalized natural gradient descent procedure that significantly speeds up the training process. Moreover, we introduce a compact interferometric measurement device, improving the scalability of our photonic QW setup that enables experimental learning of mixed states. Our results demonstrate that highly expressive neural networks can serve as powerful alternatives to traditional state tomography.

A facile, low-cost bimetallic iron-nickel MOF nanozyme-propelled ratiometric fluorescent sensor for highly sensitive and selective uric acid detection and its smartphone application.

As a kind of well-known disease biomarker, uric acid (UA) is closely associated with normal metabolism and health. Despite versatile nanozymes facilitating the analysis of UA, most previous works could only generate single-signal outputs with unsatisfactory detection performance. Exploring a novel ratiometric fluorescent UA sensor with high sensitivity, reliability and portable sensing ability based on facile, low-cost nanozymes is still challenging. Herein, we report the first metal-organic-framework (MOF) nanozyme-originated ratiometric fluorescent UA sensor based on Fe3Ni-MOF-NH2 propelled UA/uricase/o-phenylenediamine tandem catalytic reaction. Different from previous reports, the peroxidase-like property and fluorescence of Fe3Ni-MOF-NH2 were simultaneously employed. In the absence of UA, only the MOF's fluorescence at 430 nm (FI430) can be observed, while the addition of UA will initiate UA/uricase catalytic reaction, and the generated H2O2 could oxidize o-phenylenediamine into highly fluorescent 2,3-diaminophenazine (DAP) (emission at 565 nm, FI565) under the catalysis of the MOF nanozyme. Coincidently, MOF's fluorescence can be quenched by DAP via the inner filter effect, resulting in a low FI430 value and high FI565 value, respectively. Therefore, H2O2 and UA can be alternatively detected through monitoring the above contrary fluorescence changes. The limit of detection for UA is 24 nM, which is much lower than those in most previous works, and the lowest among nanozyme-based ratiometric fluorescent UA sensors reported to date. Moreover, the portable sensing of UA via smartphone-based RGB analysis was facilely achieved by virtue of the above nanozyme-propelled tandem catalytic system, and MOF nanozyme-based molecular contrary logic pairs were further implemented accordingly.

An intelligent ratiometric fluorescent assay based on MOF nanozyme-mediated tandem catalysis that guided by contrary logic circuit for highly sensitive sarcosine detection and smartphone-based portable sensing application.

As the well-known test-indicator for early prostate cancer (PCa), sarcosine (SA) is closely related to the differential pathological process, which makes its accurate determination increasingly significant. Herein, we for the first time expanded the peroxidase (POD)-like property of facile-synthesized Zn-TCPP(Fe) MOF to fluorescent substrates and exploited it to ratiometric fluorescent (RF) sensing. By harnessing the effective catalytic oxidation of MOF nanozyme toward two fluorescent substrates (Scopoletin, SC; Amplex Red, AR) with contrary changes, and target-responsive (SA + SOx)/MOF/(SC + AR) tandem catalytic reaction, we constructed the first MOF nanozyme-based RF sensor for the quantitative determination of SA. Superior to previous works, the operation of this RF sensor is under the guidance of AND-(AND^NAND) contrary logic circuit. The dual-channel binary output changes (from 1/0 to 0/1) not only enable the intelligent logical recognition of SA, bringing strengthened reliability and accuracy, but also manifest the proof-of-concept discrimination of PCa individuals and healthy ones. Through recording the fluorescence alterations of SC (F465) and AR (F585), two segments of linear relationships between ratiometric values (F585/F465) and varied contents of SA are realized successfully. The LOD for SA could reach to as low as 39.98 nM, which outperforms all nanozyme-originated SA sensors reported till now. Moreover, this sensor also demonstrates high selectivity and satisfactory performance in human serum samples. Furthermore, the portable sensing of SA is realized under the assistance of smartphone-based RGB analysis, demonstrating the potential of point-of-care diagnostics of PCa in the future.

A wearable electrostimulation-augmented ionic-gel photothermal patch doped with MXene for skin tumor treatment.

A wearable biological patch capable of producing multiple responses to light and electricity without interfering with daily activities is highly desired for skin cancer treatment, but remains a key challenge. Herein, the skin-mountable electrostimulation-augmented photothermal patch (eT-patch) comprising transparent ionic gel with MXene (Ti3C2Tx) doping is developed and applied for the treatment of melanoma under photostimulation at 0.5 W/cm2. The eT-patch designed has superior photothermal and electrical characteristics owing to ionic gels doped with MXene which provides high photothermal conversion efficiency and electrical conductivity as a medium. Simultaneously, the ionic gel-based eT-patch having excellent optical transparency actualizes real-time observation of skin response and melanoma treatment process under photothermal and electrical stimulation (PES) co-therapy. Systematical cellular study on anti-tumor mechanism of the eT-patch under PES treatment revealed that eT-patch under PES treatment can synergically trigger cancer cell apoptosis and pyroptosis, which together lead to the death of melanoma cells. Due to the obvious advantages of relatively safe and less side effects in healthy organs, the developed eT-patch provides a promising cost-effective therapeutic strategy for skin tumors and will open a new avenue for biomedical applications of ionic gels.

Label-Free Single-Cell SERS Detection and Fluorescence Imaging of Molecular Responses to Endoplasmic Reticulum Stress under Electrical Stimulation.

The endoplasmic reticulum (ER) is one of the most important organelles in eukaryotic cells, in which most proteins and lipids are synthesized to regulate complex cellular processes. Generally, the excessive accumulation of unfolded or misfolded proteins can disturb ER homeostasis and induce endoplasmic reticulum stress (ERS). Howbeit, the molecular stress responses within ERS and metastatic behaviors of tumor cells during electrical stimulation (ES) are still poorly investigated and remain a challenge. In this study, by the combined use of fluorescence imaging, ER-targeting plasmonic nanoprobes were developed to trace molecular stress response profiling within the ER during a constant-voltage ES process at ∼1 V based on label-free surface-enhanced Raman spectroscopy (SERS). The excess accumulation of ß-misfolded proteins was found after the ES, leading to breaking of the ER homeostasis and further inducing mitochondrial dysfunction. Notably, the excessive stress of ER under ES can destroy the calcium ion balance and induce significant upregulation of calreticulin expression. Importantly, the content ratio of two kinds of cadherin between E-cadherin and N-cadherin was gradually improved with the voltages boosted. Meanwhile, the epithelial adhesion factor expression was ascended with voltages amplified, leading to inhibiting tumor cell migration at low voltages or death under higher voltages (∼1 V). This study provides cellular insights into the ES approach for tumor therapy and also provides a simple and effective method for detecting molecular stress responses in endoplasmic reticulum stress.

Toward Minute-Level DNA Computing: An Ultrafast, Cost-Effective, and Universal System for Lighting Up Various Concurrent DNA Logic Nanodevices (CDLNs) and Concatenated Circuits.

DNA logic nanodevices are powerful tools for both molecular computing tasks and smart bioanalytical applications. Nevertheless, the hour-level operation time and high cost caused by the frequent redesign/reconstruction of gates, tedious strand-displacement reaction, and expensive labeled probes (or tool enzymes) in previous works are ineluctable drawbacks. Herein, we report an ultrafast and cost-effective system for engineering concurrent DNA logic nanodevices (CDLNs) by combining polythymine CuNCs with SYBR Green I (SG I) as universal dual-output producers. Particularly, benefiting from the concomitant minute-level quick response of both unlabeled illuminators and the exquisite strand-displacement-free design, all CDLNs including contrary logic pairs (YES∧NOT, OR∧NOR, and Even∧Odd number classifier), noncontrary ones (IDE∧IMP, OR∧NAND), and concatenated circuits are implemented in just 10 min via a "one-stone-two-birds" method, resulting in only 1/12 the operation time and 1/4 the cost needed in previous works, respectively. Moreover, all of them share the same threshold value, and the dual output can be easily visualized by the naked eye under a portable UV lamp, indicating the universality and practicality of this system. Furthermore, by exploiting the "positive/negative cross-verification" advantages of concurrent contrary logic, the smart in vitro analysis of the polyadenine strand and its polymerase is realized, providing novel molecular tools for the early diagnosis of cancer-related diseases.

Identifying the active sites in unequal iron-nitrogen single-atom catalysts.

Single-atom catalysts (SACs) have become one of the most attractive frontier research fields in catalysis and energy conversion. However, due to the atomic heterogeneity of SACs and limitations of ensemble-averaged measurements, the essential active sites responsible for governing specific catalytic properties and mechanisms remain largely concealed. In this study, we develop a quantitative method of single-atom catalysis-fluorescence correlation spectroscopy (SAC-FCS), leveraging the atomic structure-dependent catalysis kinetics and single-turnover resolution of single-molecule fluorescence microscopy. This method enables us to investigate the oxidase-like single-molecule catalysis on unidentical iron-nitrogen (Fe-N) coordinated SACs, quantifying the active sites and their kinetic parameters. The findings reveal the significant differences of single sites from the average behaviors and corroborate the oxidase-like catalytic mechanism of the Fe-N active sites. We anticipate that the method will give essential insights into the rational design and application of SACs.

Hyphenated DEMS and ATR-SEIRAS techniques for in situ multidimensional analysis of lithium-ion batteries and beyond.

A wide spectrum of state-of-the-art characterization techniques have been devised to monitor the electrode-electrolyte interface that dictates the performance of electrochemical devices. However, coupling multiple characterization techniques to realize in situ multidimensional analysis of electrochemical interfaces remains a challenge. Herein, we presented a hyphenated differential electrochemical mass spectrometry and attenuated total reflection surface enhanced infrared absorption spectroscopy analytical method via a specially designed electrochemical cell that enables a simultaneous detection of deposited and volatile interface species under electrochemical reaction conditions, especially suitable for non-aqueous, electrolyte-based energy devices. As a proof of concept, we demonstrated the capability of the homemade setup and obtained the valuable reaction mechanisms, by taking the tantalizing reactions in non-aqueous lithium-ion batteries (i.e., oxidation and reduction processes of carbonate-based electrolytes on Li1+xNi0.8Mn0.1Co0.1O2 and graphite surfaces) and lithium-oxygen batteries (i.e., reversibility of the oxygen reaction) as model reactions. Overall, we believe that the coupled and complementary techniques reported here will provide important insights into the interfacial electrochemistry of energy storage materials (i.e., in situ, multi-dimensional information in one single experiment) and generate much interest in the electrochemistry community and beyond.

A New Fluorescent Probe Tool: ERNathG.

ß-d-Glucuronidase (GUS) plays a pivotal role in both clinical treatment assessment and environmental monitoring. Existing tools for GUS detection suffer from (1) poor continuity due to a gap between the optimal pH of the probes and the enzyme and (2) diffusion from the detection site due to lack of an anchoring structure. Here we report a novel GUS pH-matching and endoplasmic reticulum-anchoring strategy for GUS recognition. The new fluorescent probe tool was termed ERNathG, which was designed and synthesized with ß-d-glucuronic acid as the GUS-specific recognition site and 4-hydroxy-1,8-naphthalimide as a fluorescence reporting group, with a p-toluene sulfonyl as an anchoring group. This probe enabled the continuous and anchored detection of GUS without pH-adjustment for the related assessment of common cancer cell lines and gut bacteria. The probe's properties are far superior to those of commonly used commercial molecules.

Application study of RGB color extraction in water toxicity detection.

In this work, a colorimetric biosensor based on the rapid color change of Escherichia coli DH 5α (E. coli) and p-benzoquinone (BQ) was introduced to evaluate water toxicity. Here, dark brown quinhydroquinone (QHQ) was obtained from the reaction between E. coli and BQ. The inhibition ratios were calculated by RGB (red, green, blue) values of samples or oxidation current of hydroquinone (HQ). Here, RGB technology was used for biotoxicity assessment for the first time. The results suggested that the biosensor-based RGB has an obvious dose-dependent response. The IC20 values of Hg2+ and Cu2+ obtained based on RGB values were 1.0 and 1.5 mg L-1, respectively. This biosensor can be used to detect quickly toxicity of the Cu2+ and Hg2+ in water without complicated operation steps. Therefore, the biosensor has potential application value in the field of water toxicity detection.

A novel, environmentally friendly dual-signal water toxicity biosensor developed through the continuous release of Fe3.

In this work, a novel, environmentally friendly and simple electrochemical/colorimetric water toxicity biosensor was rationally developed by the continuous release of Fe3+ in a medium. The bioluminescent bacterium Vibrio Fischeri (V. fischeri) was used for the first time as a model bacterium to assess water toxicity for a mediated electrochemical biosensor. The green substance composited by Prussian blue (PB) and yellow K3[Fe(CN)6] was used as the indicator of the colorimetric biosensor. To obtain an ideal electrochemical/colorimetric performance, analytical conditions of the bioassay including NaCl concentration, temperature, concentrations of cells and K3[Fe(CN)6], and incubation time were optimized to 0.5%, 22 oC, 4 (OD600), 10 mM, and 15 min, respectively. The IC50 values of Zn2+, Hg2+, Cd2+ and 3,5-dichlorophenol (3,5-DCP) obtained by electrochemical method were 4.7, 5.0, 17.6 and 10.6 mg/L, respectively. The limits of detection (LODs) of Zn2+, Hg2+, Cd2+ and 3,5-DCP obtained by the naked eye were 6.3, 1.6, 12.5 and 12.5 mg/L, respectively. Two real water samples taken from tap water pipe and the Yitong river were also detected sensitively, and the inhibition ratios obtained were 3.8% and 14.0%, respectively. These results indicate that the V. fischeri-based bioassay is simple, sensitive and inexpensive, which is promising alternative for acute biotoxicity assessment.

Regenerable sensor based on tris(4,7'-diphenyl-1,10-phenanthroline)ruthenium (II) for anodic and cathodic electrochemiluminescence applications.

Tris(4,7'-diphenyl-1,10-phenanthroline) ruthenium (II) dichloride [Ru(dpp)32+] was used for the first time to construct a regenerable electrochemiluminescence (ECL) sensor. The Ru(dpp)32+-modified carbon paste electrode (CPE) showed several unique features in comparison with commonly studied Ru(bpy)32+-modified electrodes. On the one hand, a quite reversible reduction peak was observed at -0.96 V where no obvious hydrogen evolution occured, enabling the sensitive detection of S2O82-. Moreover, our proposed S2O82- sensor showed a good linear range from 3 × 10-9 to 3 × 10-4 M with a detection limit of 2 nM, indicating higher sensitivity for the same analyte than previously reported ECL methods by about two orders of magnitude. On the other hand, the Ru(dpp)32+-modified electrode showed an irreversible oxidation peak because electrogenerated Ru(dpp)33+ is very reactive in aqueous solutions, while Ru(bpy)32+-modified electrode showed a reversible oxidation peak. Moreover, the present sensor showed a good linear range from 10-7 M to 10-3 M for oxalate with a detection limit of 60 nM. It detected oxalate in urine samples with nice recoveries. The regenerable ECL sensor presented good characteristics, such as low cost, simple fabrication procedure and fast response time. The Ru(dpp)32+ based regenerable sensor is an attractive alternative to Ru(bpy)32+-based regenerable sensor, as it can be used for both anodic and cathodic ECL analysis with high sensitivity in aqueous media.

Beyond Photosynthesis: H2O/H2O2/O2 Self-Circulation-Based Biohybrid Photoelectrochemical Cells for Direct and Sustainable Solar-to-Fuel-to-Electric Power Conversion.

Solar-to-fuel conversion followed by secondary utilization in fuel cells provides an appealing approach to alleviating global energy shortages but is largely restricted by the complex design of power systems and the development of functional catalysts. Herein, we presented a biohybrid photoelectrochemical cell (BPEC) to implement sustainable solar-to-fuel-to-electric power conversion in a single compartment, by ingeniously combining reliable photoelectrochemical H2O2 generation with efficient bioelectrochemical H2O2 consumption. Specifically, the BPEC is composed of a Mo-modified BiVO4 (Mo:BiVO4) photoanode and a horseradish peroxidase (HRP)/pyrene-modified 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (bis-Pyr-ABTS)/carbon nanotubes with an encapsulated Co nanoparticle (Co/CNTs) biocathode. Upon photoexcitation, two-electron H2O oxidation can be carried out at the Mo-BiVO4 photoanode to produce H2O2, followed by electroenzymatic reduction of H2O2 to H2O by HRP with the help of a bis-Pyr-ABTS redox mediator at the biocathode. Besides, in response to the insufficient Faradaic efficiency of H2O2 generation at the photoanode, the functional Co/CNTs catalysts, possessing prominent electrocatalytic selectivity toward two-electron O2 reduction (electron transfer number = 2.6), are modified on the biocathode, thus clearly defining effective H2O/H2O2/O2 self-circulation in this device. This developed BPEC obtains an open-circuit potential of 1.03 ± 0.02 V and a maximum power density of 0.18 ± 0.02 mW cm-2. Moreover, inspired by the particular advantage of enzymatic biofuel cells for easy miniaturization, an enclosed "sandwich-like" BPEC of approximately 1 cm3 size is fabricated and delivers a power output of 0.13 ± 0.03 mW cm-2. Our work represents a controllable approach for meaningful solar energy utilization, beyond traditional artificial photosynthesis, and can further provide a significant paradigm shift in building an energy-sustainable society.

Specific Nanodrug for Diabetic Chronic Wounds Based on Antioxidase-Mimicking MOF-818 Nanozymes.

Chronic wound is a common complication for diabetic patients, which entails substantial inconvenience, persistent pain, and significant economic burden to patients. However, current clinical treatments for diabetic chronic wounds remain unsatisfactory. A prolonged but ineffective inflammation phase in chronic wounds is the primary difference between diabetic chronic wounds and normal wounds. Herein, we present an effective antioxidative system (MOF/Gel) for chronic wound healing of diabetic rats through integrating a metal organic framework (MOF) nanozyme with antioxidant enzyme-like activity with a hydrogel (Gel). MOF/Gel can continuously scavenge reactive oxygen species to modulate the oxidative stress microenvironment in diabetic chronic wounds, which leads to a natural transition from the inflammation phase to the proliferation phase. Impressively, the efficacy of one-time-applied MOF/Gel was comparable to that of the human epidermal growth factor Gel, a widely used clinical drug for various wound treatments. Such an effective, safe, and convenient MOF/Gel system can meet complex clinical demands.

Platinum-Gold Alloy Catalyzes the Aerobic Oxidation of Formic Acid for Hydrogen Peroxide Synthesis.

On-site hydrogen peroxide production through electrocatalytic and photocatalytic oxygen reduction reactions has recently attracted broad research interest. However, practical applications have thus far been plagued by the low activity and the requirement of complex equipment. Here, inspired by the process of biological hydrogen peroxide synthesis catalyzed by enzymes, we report a Pt-Au alloy to mimic the catalytic function of natural formate oxidase for hydrogen peroxide synthesis through aerobic oxidation of formic acid. The mass activity of the Pt-Au alloy is three times higher than that of formate oxidase. Density functional theory calculations revealed that the efficient dehydrogenation of formic acid and the high selectivity of the subsequent reduction of oxygen to hydrogen peroxide account for the high hydrogen peroxide productivity. In addition, the formic acid aqueous solution provides an acidic environment, which is conducive to the utilization of the in situ generated hydrogen peroxide for oxidation reactions, including C-H bond oxidation and sterilization.

Reversible inhibition of the oxidase-like activity of Fe single-atom nanozymes for drug detection.

Mechanism research of nanozymes has always been of great interest since their emergence as outstanding mimics of friable natural enzymes. An important but rarely mentioned issue in mechanism research of nanozymology is the inhibitory effect of nanozymes. And conventional nanozymes with various active sites hinder the mechanism research, while single-atom Fe-N-C nanozymes with similar active sites to natural enzymes exhibit structural advantages. Herein, we synthesized Fe single-atom nanozymes (Fe-SANs) with ultrahigh oxidase-like activity and found that a common analgesic-antipyretic drug 4-acetamidophenol (AMP) had inhibitory effects for the oxidase-like activity of Fe-SANs. We investigated the inhibitory effects in detail and demonstrated that the inhibition type was reversible mixed-inhibition with inhibition constants (K i and ) of 0.431 mM and 0.279 mM, respectively. Furthermore, we put forward a colorimetric method for AMP detection based on nanozyme inhibition. The research on the inhibitory effects of small molecules on nanozymes expands the scope of analysis based on nanozymes and the inhibition mechanism study may offer some insight into investigating the interaction between nanozymes and inhibitors.

Kinetically restrained oxygen reduction to hydrogen peroxide with nearly 100% selectivity.

Hydrogen peroxide has been synthesized mainly through the electrocatalytic and photocatalytic oxygen reduction reaction in recent years. Herein, we synthesize a single-atom rhodium catalyst (Rh1/NC) to mimic the properties of flavoenzymes for the synthesis of hydrogen peroxide under mild conditions. Rh1/NC dehydrogenates various substrates and catalyzes the reduction of oxygen to hydrogen peroxide. The maximum hydrogen peroxide production rate is 0.48 mol gcatalyst-1 h-1 in the phosphorous acid aerobic oxidation reaction. We find that the selectivity of oxygen reduction to hydrogen peroxide can reach 100%. This is because a single catalytic site of Rh1/NC can only catalyze the removal of two electrons per substrate molecule; thus, the subsequent oxygen can only obtain two electrons to reduce to hydrogen peroxide through the typical two-electron pathway. Similarly, due to the restriction of substrate dehydrogenation, the hydrogen peroxide selectivity in commercial Pt/C-catalyzed enzymatic reactions can be found to reach 75%, which is 30 times higher than that in electrocatalytic oxygen reduction reactions.

Recent advancements in coralyne (COR)-based biosensors: Basic principles, various strategies and future perspectives.

As a kind of protoberberine alkaloid heterocyclic analogues, coralyne (COR) has been reported to exhibit superior antileukemic ability and used as anticancer drug agent. While, the severe hazards and side effects caused by unreasonable use have made its accurate detection more and more important. Although scientists have explored various methods to sense COR and other related targets, a systematical review which could not only elaborate recent developments and analyze current challenges of COR-based biosensors, but also present future perspective has not been reported and is urgently needed. In this review, we attempt to summarize latest advancements in COR-based biosensors in recent decade. Firstly, the operating principles, advantages and disadvantages of various strategies for COR detection (colorimetric, fluorescent, electrochemical and other ones) are comprehensively demonstrated and reviewed. Secondly, COR-assisted biosensors for detection of different non-COR targets (heparin, toxins, nucleic acids and other small molecules) are further discussed. Finally, we analyze current challenges and also suggest potential perspectives for this area.