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Monitoring of kanamycin residue has attracted considerable attention owing to the potential harm caused by the abuse of kanamycin. However, the detection of kanamycin has been limited owing to its electrochemical and optical inertness. Herein, we report a facile and highly efficient electrochemiluminescence (ECL) strategy for the detection of kanamycin based on the valence state effect of gold nanocluster (AuNC) probes. It is proven that Au0 in chemically reduced AuNCs (CR-AuNCs) could be oxidized to AuI via the redox reaction between kanamycin and CR-AuNCs in the presence of H2O2, resulting in ECL quenching due to the valence state change of CR-AuNCs. Because the ECL of the AuNC probes is sensitively affected by the valence state, excellent sensitivity for kanamycin was achieved without any signal amplification operation and aptamers. A preferable linear-dependent curve was acquired in the detection range from 1.0 × 10-11 to 3.3 × 10-5 M with an extremely low detection limit of 1.5 × 10-12 M. The proposed kanamycin sensing platform is very simple and shows high selectivity and an extremely broad linear range detection of kanamycin. Furthermore, the proposed sensing platform can detect kanamycin in milk samples with excellent recoveries. Therefore, this sensing strategy provides an effective and facile way to detect kanamycin and can help promote the understanding of the constructed mechanism of the AuNC-based ECL system, thus greatly broadening its potential application in ECL fields.

Clear-cell renal cell carcinoma (ccRCC) carries a variable prognosis. Prognostic biomarkers can stratify patients according to risk, and can provide crucial information for clinical decision-making. We screened for an autophagy-related long non-coding lncRNA (lncRNA) signature to improve postoperative risk stratification in The Cancer Genome Atlas (TCGA) database. We confirmed this model in ICGC and SYSU cohorts as a significant and independent prognostic signature. Western blotting, autophagic-flux assay and transmission electron microscopy were used to verify that regulation of expression of 8 lncRNAs related to autophagy affected changes in autophagic flow in vitro. Our data suggest that 8-lncRNA signature related to autophagy is a promising prognostic tool in predicting the survival of patients with ccRCC. Combination of this signature with clinical and pathologic parameters could aid accurate risk assessment to guide clinical management, and this 8-lncRNAs signature related to autophagy may serve as a therapeutic target.

The even order harmonics of the flux linkage naturally exist in every armature coil of stator-permanent magnet (PM) machines, while it is usually a basic requirement to have the symmetrical phase flux linkage free from even order harmonics. Thus, the specific harmonics must be eliminated after the coil connection. In this article, the general mechanism of the even order harmonics elimination in various stator-PM machines is investigated, and it is found that either the opposite PM polarities or the opposite coil polarities of the two adjacent phase coils can guarantee the elimination effect, and hence, the symmetrical phase flux linkages. This principle can be applied to both bipolar flux and unipolar flux machines. The analysis is validated by finite-element method and the test results of the prototype machine.

The use of metal ions to bridge the fluorescent materials to target analytes has been demonstrated to be a promising way to sensor design. Herein, the effect of rare-earth ions on the fluorescence of l-methionine-stabilized gold nanoclusters (Met-AuNCs) was investigated. It was found that europium (Eu3+) can significantly suppress the emission of Met-AuNCs, while other rare-earth ions showed a negligible impact. The mechanism on the observed fluorescence quenching of Met-AuNCs triggered by Eu3+ was systematically explored, with results revealing the dominant role of photoinduced electron transfer (PET). Eu3+ can bind to the surface of Met-AuNCs by the coordination effect and accepts the electron from the excited Met-AuNCs, which results in Met-AuNC fluorescence suppression. After introducing dipicolinic acid (DPA), an excellent biomarker for spore-forming pathogens, Eu3+ was removed from the surface of Met-AuNCs owing to the higher binding affinity between Eu3+ and DPA. Consequently, an immediate fluorescence recovery occurred when DPA was present in the system. Based on the Met-AuNC/Eu3+ ensemble, we then established a simple and sensitive fluorescence strategy for turn-on determination of biomarker DPA, with a linear range of 0.2-4 μM and a low limit of detection of 110 nM. The feasibility of the proposed method was further validated by the quantitative detection of DPA in the soil samples. We believe that this study would significantly facilitate the construction of metal-ion-mediated PET sensors for the measurement of various interested analytes by applying fluorescent AuNCs as detection probes.

Leaf color has been considered an important agronomic trait in rice (Oryza sativa L.) for a long time. The changes in leaf color affect the yield of rice. In this study, a green-revertible albino (graS) mutant was isolated from a 60Co-gamma-irradiated mutant pool of indica cultivar Guangzhan 63-4S. The fine mapping indicated that graS mutant was mapped to chromosome 1, and was located in a confined region between markers ab134 and InDel 8 with genetic distances of 0.11 and 0.06 cM, respectively. Based on the annotation results, four open reading frames (ORFs) were predicted in this region. Sequence analysis revealed that LOC_Os01g55974 had a 2-bp nucleotide insertion (AA) in the coding region that led to premature termination at the 324th base. Sequence analysis and expression analysis of related genes indicated that LOC_Os01g55974 is the candidate gene of GraS. We studied the genome and protein sequences of LOC_Os01g55974, and the data showed that GraS contains a deoxycytidine deaminase domain, which was expressed ubiquitously in all tissues. Further investigation indicated that GraS plays an essential role in the regulation of chloroplast biosynthesis, photosynthetic capacity and yield. Moreover, leaf color mutant can be used as an effective marker for the purity of breeding and hybridization.

Nanozymes, or nanomaterials that mimic the behaviors of enzymes, are highly promising materials for biomedical applications because of their excellent chemical stability under harsh conditions, simple preparation method and lower costs compared with natural enzymes. We herein report the intrinsic oxidase-mimicking activity of molybdenum oxide nanoparticles (MoO3 NPs). MoO3 NPs catalyzed the oxidation of colorless 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) to green product. The catalytic mechanism of the oxidase-mimicking activity of the MoO3 NPs was investigated in detail using electron spin resonance and a radical inhibition method. The oxidation of ABTS stems from 1O2 generated from the interaction between MoO3 NPs and dissolved oxygen in the solution. Acid phosphatase (ACP) catalyzes the hydrolysis of the ascorbic acid 2-phosphate (AAP) substrate to produce ascorbic acid (AA). AA was found to fade the coloration process of the MoO3 NP-mediated ABTS oxidation. By combining the oxidase-mimicking property of the MoO3 NPs and the ACP-catalyzed hydrolysis of AAP, a novel and simple colorimetric method for detecting ACP was established. The linear range for ACP determination is 0.09-7.3 U/L with a detection limit of 0.011 U/L. This new colorimetric method was successfully applied to the detection of ACP in diluted human serum samples and screening of ACP inhibitors. The present study proposes MoO3 NPs as a new oxidase mimic for establishing various biosensing method.

Protein-supported nanoparticles have a great significance in scientific and nanotechnology research because of their “green” process, low cost-in-use, good biocompatibility, and some interesting pr...

Ongoing efforts have contributed to the exploration of peroxidase-like nanozymes while preserving their benefits in bioassays. Unfortunately, many peroxidase-like nanozymes still exhibit a low catalytic activity accompanied by oxidase-like activity with interferences of O2 and color which limit their applicability. Herein, we carried out a “green” approach to synthesize citrate-coated osmium nanozyme with a high peroxidase-like performance. Comprehensive experiments were validated in which the Os nanozyme could achieve excellent steady-state kinetic parameters and a high specific activity (393 000 Unit per g), which was better than those of most reported nanozymes. More significantly, the Os nanozyme possesses a higher peroxidase-like activity and negligible oxidase-like activity compared with those of common noble metal-based nanozymes (Pt and Au), freeing the corresponding assay system from the interference of O2 and color. In addition, the Os nanozyme presents robustness against complex environments and some metal ions that usually act as noble metal-based nanozymes. As a proof-of-concept, the Os nanozyme has been successfully employed to fabricate colorimetric assays for glucose and pyruvic acid detections with the associated color gradients. These findings collectively prove that the Os nanozyme could be a novel and promising peroxidase mimic candidate for bioassays and beyond.

A visual assay for the detection of heparinase was developed on the basis of a ternary system of Hg2+–heparin–osmium nanoparticles (OsNPs). First, heparin-capped OsNPs (heparin–OsNPs) were synthesi...

Ligand-protected gold nanoclusters (AuNCs) have emerged as a new class of electrochemiluminescence (ECL) luminophores for their interesting catalytic and emission properties, although their quantum yield (ΦECL ) in aqueous medium is low with a poor mechanistic understanding of the ECL process. Now it is shown that drying AuNCs on electrodes enabled both enhanced electrochemical excitation by an electrocatalytic effect, and enhanced emission by aggregation-induced ECL (AIECL) for 6-aza-2-thiothymine (ATT) protected AuNCs with triethylamine (TEA) as a coreactant. The dried ATT-AuNCs/TEA system resulted in highly stable visual ECL with a ΦECL of 78 %, and a similar enhancement was also achieved with methionine-capped AuNCs. The drying enabled dual-enhancement mechanism has solved a challenging mechanistic problem for AuNC ECL probes, and can guide further rational design of ECL emitters.

Although numerous sensors have been successfully fabricated for the detection of various heavy metal ions by employing fluorescent gold nanoclusters (AuNCs) as nanoprobes, serious cross-interference often occurs when these ions coexist in samples, which results in glaring errors in quantification. In this study, glutathione-protected AuNCs (GSH-AuNCs) were synthesized and found to respond to both Cu2+ and Hg2+ via fluorescence suppression. Intriguingly, addition of Ag+ to GSH-AuNCs could completely inhibit the quenching effect of Hg2+ while not affecting the Cu2+-mediated quenching process. Ag+ can combine with Au+ on the surface of AuNCs to form a strong Ag+-Au+ metallic bond, which disrupts the interaction between Hg2+ and Au+ and thus eliminates the corresponding quenching effect. Based on this phenomenon, a simple sensing approach for highly selective and sensitive detection of Cu2+ in aqueous solution was developed using the GSH-AuNC/Ag+ complex as a fluorescent turn-off nanoprobe. The proposed method exhibited good linearity in the concentration range 0.02–10 μM with a limit of detection of 12 nM. This assay was demonstrated to be suitable for determination of Cu2+ in real water samples even in the presence of Hg2+, showing great promise as a tool for assessment of environmental security and drinking water quality.

The development of efficient methods for the detection of hazardous and toxic elements is extremely important for environmental security and public health. In this work, we developed a facile colorimetric assaying system for Ag+ detection in aqueous solution. Chitosan-stabilized platinum nanoparticles (Ch-PtNPs) were synthesized and severed as an artificial oxidase to catalyze the oxidation of the substrate 3,3′,5,5′-tetramethylbenzidine (TMB) and generate color signal. In the presence of Ag+, due to the strong metallophilic interactions between Ag+ and Pt2+ on the surface of Ch-PtNPs, Ag+ can weaken the affinity to the substrates and inactivate the catalytic activity of Ch-PtNPs, leading to decreased absorbance signal to varying degrees depending on Ag+ amount. Combing the specific binding between Ch-PtNPs and Ag+ with signal amplification procedure based on the Ch-PtNPs-catalyzed TMB oxidation, a sensitive, selective, simple, cost-effective, and rapid detection method for Ag+ can be realized. Ag+ ions in tap and lake waters have been successfully detected. We ensured that the proposed method can be a potential alternative for Ag+ determination in environmental samples.

Few-atom gold nanoclusters (AuNCs) have been fabricated and used for various fields owing to their remarkable optical and photophysical features. However, the rational design for the antibody-mediated synthesis of fluorescent AuNCs for direct antigen-antibody reactions remains unexplored. In this work, immunoglobulin G (IgG)-functionalized AuNCs (IgG-AuNCs) were successfully prepared via a facile and fast biomineralization process. The generated IgG-AuNCs can emit intense red fluorescence with a high photoluminescence quantum yield. Besides strong emission, the bioactivity of IgG on the IgG-AuNCs can be retained. Surface plasmon resonance measurements suggested that IgG-AuNCs can bind to goat anti-human IgG with an affinity constant of 6.21 × 10-8 M. A simple detection method was then developed using a dot-blot immunoassay with IgG-AuNCs as fluorescent tags. Experimental results confirmed that the IgG-AuNC-based fluorescent reporters had many advantages such as low nonspecific adsorption and good photostability, offering immense potential for the development of efficient biosensors. This work can be extended to other specific antibodies to produce multifunctional AuNCs and utilized to detect and monitor targeted analytes and biological events of interest.

A nondestructive system for measuring the soluble solids content (SSC) and firmness of wax apples was developed using 670, 850, 880, 940, and 980 nm visible–shortwave–near-infrared (Vis-SW-NIR) light-emitting diode (LED) light sources and a silicon (Si) photodetector. These specified wavelengths are highly correlated with the SSC and the firmness of fruit. An LED light source was incident onto the fruit as parallel-polarized waves (P-wave) at the Brewster angle (θB) to minimize the interfacial reflection and maximize the C–H and O–H bonds absorption signals from the fruit. Partial least squares (PLS) regression is used to build calibration modes and analyze the prediction of the correlation ([Formula: see text]) and the root mean square error for prediction (RMSEP) of the reflected optical signals with SSC and firmness. This resulted in [Formula: see text] and RMSEP values of 0.87 and 0.66 °Bx, respectively, in SSC measurements and 0.80 and 1.16 N/cm2, respectively, in firmness measurements. Therefore, the result shows [Formula: see text] of SSC and firmness are 6.4% and 9% higher and the RMSEP are 14% and 20% lower, respectively, than those obtained using non-polarized LED light sources.

Gold nanoclusters (AuNCs) are attractive electrochemiluminescence (ECL) emitters because of their excellent stability, near IR emission, and biocompatibility. However, their ECL quantum yield is relatively low, and our limited fundamental understanding has hindered rational improvement of this parameter. Herein, we report drastic enhancement of the ECL of ligand-stabilized AuNCs by on-electrode pre-oxidation with triethylamine (TEA) as a co-reactant. The l-methionine-stabilized AuNCs resulted in a record high ECL yield of 66 %. This strategy was successfully extended to other AuNCs, and it is more effective for ligand shells that allow more effective electron transfer. In addition, excitation of the pre-oxidized ECL required a lower potential than conventional methods, and no additional instrument was required. This work opens avenues for solving a challenging problem of AuNC-based ECL probes and enriches fundamental understanding, greatly broadening their potential applications.

This report outlines a versatile high-performance electrochemiluminescence (ECL) enzyme-linked immunosorbent assay (ELISA) platform, which combines the merits of high-quantum-yield Au nanocluster (AuNC) probe-based ECL technology, the efficient ECL-resonance energy-transfer (ECL-RET) strategy, and highly sensitive and specific ELISA technology. The ECL detection procedure was performed on a recyclable MnO2/AuNC-modified glassy carbon electrode interface by taking advantage of the ECL-RET between the AuNC probe and MnO2 nanomaterials (NMs) to quench the ECL intensity. The etching of MnO2 NMs by the product of ALP-based ELISA recovers the ECL signal. Notably, the ELISA process and the ECL detection procedure in this system are independent. Thus, the ECL-ELISA system can effectively avoid the influence of complex biological samples, and the ECL efficiency of the AuNC probe can be used readily. As demonstrated on TNF-α, because of the abovementioned characteristics, the ECL-ELISA platform presented an extremely wide dynamic range, with a detection limit of 2 orders lower than ELISA. Moreover, the system was also applicable for ultrahigh sensitive detection of various disease-related proteins and able to detect trace biomarkers in real serum samples. Therefore, this multifunctional ECL assay platform is versatile, facile, ultrasensitive, recyclable, and sufficiently straightforward for trace biomarker detection in complex biological samples. This approach not only enriches the foundational study of ECL devices but also greatly expands the potential application of ECL sensors in biological testing and clinical high-throughput diagnosis.

Lithocarols A-F (1–6) possessing novel highly-oxygenated isobenzofuran core, together with a related known compound isoprenylisobenzofuran A (7) were isolated from the marine-derived fungus Phomopsis lithocarpus FS508. Among them, lithocarols A-E (1–5) represent the first examples of poly-ketal derivatives in tenellone family. The structures for all these compounds were fully elucidated by spectroscopic analysis, X-ray diffraction, and electronic circular dichroism calculations. Their cytotoxic assay disclosed that compounds 1–4 displayed moderate growth inhibitory effect against four human tumor cell lines with the IC50 values ranging from 10.5 to 38.7 μM.

Hybrid permanent-magnet (PM) variable-flux memory (VFM) machines employ both high coercive force PM, i.e., the constant PM (CPM), and low coercive force PM, i.e., the variable PM (VPM). The high energy-product CPM guarantees the benefits of high torque density of the conventional PM machines, while the PM magnetization state of the VPM is flexibly regulated to match various operation requirements. In fact, the two kinds of PMs can be magnetically connected in either parallel or series, with which the machine characteristics are quite different. In this paper, based on the two-dimensional and three-dimensional finite-element analyses, a pair of VFM machines with parallel and series connections, respectively, are investigated with specific reference to identify their difference in end effects. The comparison results show that the series hybrid PM VFM machine suffers more serious end leakage flux. The prototype machines are manufactured and tested to validate the analyses and predictions.

Variable flux memory (VFM) permanent magnet (PM) machines exhibit an additional degree of freedom for control, i.e., PM magnetization state, and thus excellent flux controllability. Moreover, the hybrid PM topologies having variable PM (VPM) with low coercive force and constant PM (CPM) with high coercive force at the same time are employed to improve the torque density and the flux controllability. The parallel and series connections between the two different kinds of PMs are both feasible. Based on equivalent magnetic circuits, two-dimensional finite element analyses and experiments, the VFM machines with these two connection types are investigated and compared in this paper. The results reveal that the VPM with series-connected CPM is beneficial for more stable working point and higher torque density. A pair of VFM prototypes with parallel and series hybrid PMs are manufactured and tested to validate the analyses.

Although it has been demonstrated that rare-earth elements (REEs) disturb and alter the catalytic activity of numerous natural enzymes, their effects on nanomaterial-based artificial enzymes (nanozymes) have been seldom explored. In this work, the influence of REEs on the peroxidase-like activity of bare gold nanoparticles (GNPs) is investigated for the first time, and a new type of Ce3+-activated peroxidase mimetic activity of GNPs is obtained. The introduced Ce3+ can be bound to the bare GNP surface rapidly through electrostatic attraction, after which it donates its electron to the bare GNP. As H2O2 is a good electron scavenger, more •OH radicals are generated on the surfaces of the bare GNPs, which can considerably enhance TMB oxidation. Due to its redox cycling ability, the activation effect of Ce3+ is proved to be more efficient in comparison to those of the other reported metal ion activators (e.g., Bi3+, Hg2+, and Pb2+). In addition, it is determined that Ce3+ should directly contact with the gold core to trigger its activation effect. When the surface states of the bare GNPs are altered, the Ce3+-stimulated effect is strongly inhibited. Furthermore, a novel colorimetric method for Ce3+ is developed, on the basis of its enhancing effect on the peroxidase mimetic activity of bare GNPs. The sensitivity of this newly developed method for Ce3+ is excellent with a limit of detection as low as 2.2 nM. This study not only provides an effective GNP-based peroxidase mimic but also contributes in realizing new applications for nanozymes.

Lithocarpinols A (1) and B (2), a pair of tenellone diastereoisomers with novel fused skeleton were isolated from the deep-sea derived fungus Phomopsis lithocarpus FS508. Their structures were elucidated by comprehensive spectroscopic analyses, X-ray diffraction and quantum molecular calculation. Their plausible biogenetic pathway featured an intriguing carbonyl-ene cyclization. Lithocarpinol A exhibited moderate inhibitory effect against HepG-2 and A549 tumor cell lines with IC50 values of 9.4 μmol/L and 10.9 μmol/L, respectively.

The culture broth of Cerrena sp. A593, which was isolated from Pogostemon cablin, showed potent cytotoxicity against several human tumor cell lines. The following chemical study resulted in the iso...

Four novel benzophenone derivatives, cytosporins A-D (1-4), hemiterpene-conjugated phenolics with an unprecedented benzo[b][1,5]dioxocane skeleton, were isolated from Cytospora rhizophorae A761. The structures of the new compounds were fully characterized on the basis of extensive spectroscopic analysis. The deduced structure represents the first example of natural meroterpenoids which bear a benzo[b][1,5]dioxocane framework embodying hemiterpene and benzophenone moieties. Moreover, compounds 1-4 were evaluated for in vitro antimicrobial activity.

A pair of novel enantiomeric benzophenone-hemiterpene adducts, (+)-cytorhizophin A (1a) and (−)-cytorhizophin A (1b) as well as cytorhizophin B (2), all of them featuring an unprecedented 6/7/6/7 tetracyclic fused ring system, together with their biosynthetically related precursor cytorhizophin C (3) were isolated from Cytospora rhizophorae A761. Their structures were fully characterized on the basis of extensive spectroscopic analysis, with the absolute configurations of 1 determined by X-ray diffraction and electronic circular dichroism (ECD) calculations. Moreover, compounds 1–3 were evaluated for in vitro antimicrobial activity.

Titanium dioxide has received great attention as a photocatalyst. However, due to the relatively large bandgap energy of TiO2 and fast recombination of photogenerated electron–hole pairs, various a...

Our scanning tunneling microscopy (STM) study observes, for the first time, twin domain boundary (TDB) formations on the surface of WTe2 single crystal, which is glued by solidifying indium to Si substrate. In these TDB regions, a large inhomogeneous strain field, especially a critical shear strain of about 7%, is observed by geometric phase analysis. This observation does not obey the old believe that a small mechanical stress is sufficient to drive thermally-induced TDB formations in two-dimensional materials. To resolve the contradiction, we perform density functional theory calculations combined with elasticity theory analysis, which show that TDBs on WTe2 are entirely displacement-induced, for which a critical strain is necessary to overcome the onset barrier.

The sensitive analysis of DNA is of extreme importance in the field of clinical diagnosis, targeted therapeutics, gene therapy, and a variety of biomedical studies. Even though significant achievements have been made in the detection of single-stranded DNA (ssDNA), facile strategy for the detection of double-stranded DNA (dsDNA) is still lacking. In this study, we have constructed an electrochemical DNA sensor based on homogeneous hybridization. Target dsDNA is thermal denatured and hybridized with thiolated capture probe and biotin-labeled reporter probe in solution phase. Excessive amount of the probes and precise control of hybridization temperature ensure the predominant formation of sandwich SH-dsDNA-biotin rather than reannealing product of the target dsDNA. A bovine serum albumin (BSA)-modified gold surface is designed to improve self-assembly capability of the sandwich SH-dsDNA-biotin structure in the presence of excessive SH-ssDNA probe. Thus, the target dsDNA can be successfully detected by using enzyme-linked amperometric amplification. By employing this strategy, dsDNA can be detected in a linear range from 5 pM to 1 nM with a detection limit down to 800 fM (S/N = 3). Cryptococcus neoformans in clinical real samples from cryptococcal meningitis patients can be discriminated successfully by the proposed method. Our research would make the electrochemical biosensor be an excellent candidate for pathogens detection in clinical diagnosis and prognosis.

The Erdős-Rényi (ER) random graph G(n, p) analytically characterizes the behaviors in complex networks. However, attempts to fit real-world observations need more sophisticated structures (e.g., multilayer networks), rules (e.g., Achlioptas processes), and projections onto geometric, social, or geographic spaces. The p-adic number system offers a natural representation of hierarchical organization of complex networks. The p-adic random graph interprets n as the cardinality of a set of p-adic numbers. Constructing a vast space of hierarchical structures is equivalent for combining number sequences. Although the giant component is vital in dynamic evolution of networks, the structure of multiple big components is also essential. Fitting the sizes of the few largest components to empirical data was rarely demonstrated. The p-adic ultrametric enables the ER model to simulate multiple big components from the observations of genetic interaction networks, social networks, and epidemics. Community structures lead to multimodal distributions of the big component sizes in networks, which have important implications in intervention of spreading processes., Scientific Reports, 11 (1), ISSN:2045-2322

Persistent high-risk human papillomavirus (HPV) infection is the leading cause of cervical cancer. Efficient detection of HPV16 E7 is necessary for early diagnosis and cure of the disease. Here, a novel and high-performance Au nanocluster (AuNC) probe-based split-type electrochemiluminescent (ECL) assay platform has been established to detect these oncogenes, in which the nucleic acid hybridization assay and the ECL measurements are performed independently. The proposed approach combines superior magnetic nanobead enrichment and separation technology, specific nucleic acid hybridization technology, and high-efficiency AuNC probe ECL strategy, and shows excellent advantages. First, the split-type ECL sensing platform can effectively avoid interference from biological samples and adequately uses the ECL efficiency of the AuNC probe. Furthermore, the ultrahigh sensitivity assay of HPV DNA can be achieved without any complex nucleic acid amplification technique. Taking advantage of the above merits of split-type detection, the ECL DNA sensor achieved ideal low detection of 6.8 aM and a wide dynamic range bridging 10 orders of magnitude HPV16 E7. Furthermore, together with its favorable and powerful specificity, high sensitivity, and good selectivity, this strategy could detect HPV16 E7 DNA in human samples, which showed great consistency with the FDA-approved approach (Hybrid capture 2, HC2). Therefore, this work proposes a facile and reliable split-type ECL platform for HPV diagnosis and shows great potential for the early diagnosis of other diseases.

There is a continuing high demand to design effective sensors for the determination of heavy metal ions (HMIs) since they are hazardous to both human health and the environment. In this study, we reported a facile fluorescent sensor array for rapid discrimination of HMIs based on a single gold nanocluster (AuNC) probe. This AuNC probe was prepared by using 2-mercapto-1-methylimidazole (MMI) as a ligand and polyvinypyrrolidone (PVP) as a dispersing agent. The fluorescence emission of PVP/MMI-AuNC was observed to be closely related to the pH value of the aqueous solution, which displays yellow (λmax = 512 nm) and red (λmax = 700 nm) fluorescence at pH 12.0 and 6.0, respectively. Further experiments indicated that different HMIs can produce differential effects on the photoluminescence of PVP/MMI-AuNC and thus generate distinct fluorescent responses at 512 and 700 nm. On the basis of this phenomenon, a fluorescent sensor array based on the PVP/MMI-AuNC was then built by simply changing pH value in the sensor element. A total of seven HMIs had their unique response patterns and were successfully distinguished by hierarchical cluster analysis and linear discriminant analysis both in buffer solution and spiked water samples, achieving 100% identification accuracy. This study provides a simple and powerful fingerprinting sensing platform for multiple HMIs, showing broad application prospects in the field of environmental monitoring.

Platinum nanozymes exhibiting highly efficient and robust oxidase-like activity are successfully synthesized and modified using sodium alginate (SA-PtNPs). According to a steady-state dynamic assay, Michaelis-Menton constant (K m ) is calculated as 11.6 μM, indicating that the affinity of SA-PtNPs toward the substrate, 3, 3', 5, 5'-tetramethylbenzidine (TMB), is high. It shows in the paper that SA-PtNPs exhibit a significant oxidant effect on substrate-O2 to produce O 2 • - as an oxidase mimic. Moreover, the oxidase-like activity fluctuated slightly under changes in environmental pH and incubation time, implying that SA can increase the dispersibility and stability of PtNPs. A colorimetric assay for oligomeric proanthocyanidins (OPC) was realized given how few explorations of the former there are. We found that the significant inhibitory effect of OPC on the oxidase-like activity is due to the competitive effect between OPC and TMB for binding to the active site of SA-PtNPs, resulting in a color change. Under optimal conditions, the logarithmic value of the chromogenic difference (ΔA450nm) to OPC concentration was linear (4-32.5 μM, r = 0.999) with a limit of detection (LOD) of 2.0 μM. The antioxidant capacity of OPC obtained by the Soxhlet extraction method from grape seeds was 2.85 U/mg. The recovery from the experiment in which OPC was added to grape seeds ranged from 97.0 to 98.6% (RSDs of 0.5-3.4%), suggesting a high accuracy in OPC detection. These findings are important because OPC is an internationally recognized antioxidant that eliminates free radicals in the human body and, therefore, may prevent a variety of diseases. Thus, we envisage that this Pt nanozyme-based assay may be prevalent for antioxidant capacity evaluation and analytical applications.

Monitoring nicotine concentrations in human fluids is extremely crucial owing to the harmful effect of nicotine on human health. Herein, it is shown that nicotine could quench the cathodic electrochemiluminescence (ECL) of gold nanoclusters (AuNCs) with high efficiency. The ECL quenching mechanism of nicotine was studied in detail using various experimental tools and theoretical calculations. It was concluded that the strongly oxidizing intermediate SO

One new cerapicane cerrenin A (1), and two new isohirsutane sesquiterpenoids cerrenins B and C (2 and 3), were isolated from the broth extract of Cerrena sp. A593. Cerrenin A featured a rare cage-like bicyclo[3.2.1]octane skeleton, and cerrenin B represented the rearranged triquinane-type sesquiterpenoid. Their structures were extensively elucidated by NMR spectroscopic analysis with the absolute configuration determined by X-ray crystallography and ECD calculations. The anti-cancer activity for all the compounds were evaluated, and their plausible biosynthetic relationships involving fascinating carbon skeleton rearrangements were also suggested.

Donor-linker-acceptor (D-L-A)-based photoinduced electron transfer (PET) has been frequently used for the construction of versatile fluorescent chemo/biosensors. However, sophisticated and tedious processes are generally required for the synthesis of these probes, which leads to poor design flexibility. In this work, by exploiting a Schiff base as a linker unit, a covalently bound D-L-A system was established and subsequently utilized for the development of a PET sensor. Cysteamine (Cys) and N-acetyl-l-cysteine (NAC) costabilized gold nanoclusters (Cys/NAC-AuNCs) were synthesized and adopted as an electron acceptor, and pyridoxal phosphate (PLP) was selected as an electron donor. PLP can form a Schiff base (an aldimine) with the primary amino group of Cys/NAC-AuNC through its aldehyde group and thereby suppresses the fluorescence of Cys/NAC-AuNC. The Rehm-Weller formula results and a HOMO-LUMO orbital study revealed that a reductive PET mechanism is responsible for the observed fluorescence quenching. Since the pyridoxal (PL) produced by the acid phosphatase (ACP)-catalyzed cleavage of PLP has a weak interaction with Cys/NAC-AuNC, a novel turn-on fluorescent method for selective detection of ACP was successfully realized. To the best of our knowledge, this is the first example of the development of a covalently bound D-L-A system for fluorescent PET sensing of enzyme activity based on AuNC nanoprobes using a Schiff base.

Herein, we developed a nondestructive detection system with low prediction errors for determining the vitamin C content in Indian jujube. This system comprises a Ge photodetector, a halogen lamp and five near-infrared (NIR) bandpass filters. The detection of vitamin C is enabled by the absorption of its OH and CH2 bonds in the NIR region. The light beams of our system were parallel-polarized and designed to be incident on the fruit at the Brewster angle (&theta, B), which reduces reflectance noise from the fruit&rsquo, s skin and enhances the OH and CH2 absorption signals of the fruit&rsquo, s flesh. After the reflectance signal was analyzed by the partial least squares (PLS) algorithm to obtain the predicted vitamin C content of each fruit, the coefficient of prediction ( r p 2 ) and root-mean-square error of prediction (RMSEP) were calculated. When wavelengths of 1200, 1400, 1450, 1500 and 1550 nm were used for probing, r p 2 and RMSEP of the system detecting vitamin C were 0.84 and 1.65 mg/100 g, respectively. In summary, the vitamin C content of Indian jujube was predicted using a low-cost NIR detection system having a high r p 2 and low RMSEP, further, it comprises five parallel-polarized NIR beams and the PLS algorithm.

Molybdenum oxide quantum dots (MoOx QDs) were synthesized by a one-pot method and used as a versatile probe in an electrochemiluminescent (ECL) immunoassay of the non-small cell lung cancer biomarker cytokeratin 19 fragment 21–1 (CYFRA21-1) as a model analyte. The MoOx QDs exhibited stable and strong cathodic green ECL, with an emission peak at 535 nm, in the presence of K2S2O8 within the potential range of −2.0 to 0 V. On exposure to CYFRA21-1, the ECL decreases because of the immunoreaction between CYFRA21-1 and its antibody which generates a barrier for electron transfer. The determination of CYFRA21-1 with favorable analytical performances was successfully realized under the optimal conditions. ECL decreases linearly in the 1 pg mL−1 to 350 ng mL−1 CYFRA21-1 concentration range, and the detection is as low as 0.3 pg mL−1. Excellent recoveries from CYFRA21-1-spiked human serum indicate that the assay can be operated under physiological conditions.

Gold nanoclusters (AuNCs) have attracted much attention as signal transducers in photoluminescence chemical/biological sensors. Herein, we employ bovine serum albumin/3-mercaptopropionic acid co-modified AuNCs as a fluorescence probe, Fe3+ as a quencher, and pyrophosphate as an alkaline phosphatase (ALP) substrate and Fe3+ chelator to design a novel biosensor for ALP detection, achieving a detection linear range of 0.8–16 U/L and a detection limit of 0.78 U/L. The developed method is successfully applied to the detection of ALP in human osteosarcoma cells and is shown to be suited for ALP inhibitor screening.

We present a systematic method for producing double-sided minimal surfaces by wire-cut machines. A link between minimal surfaces and ruled surfaces is pursued through wire cutting. Weierstrass parameterization is employed to define minimal surfaces ( $$\mathbb {R}^3$$ ) over a complex plane ( $$\mathbb {C}$$ ). Our method consists of three components. First, the orthogonal double-sided cuts match a pair of orthonormal tangent vectors on the surface. Second, A closed-form expression for the principal directions facilitates the global quadrangulation of minimal surfaces. Third, the CNC machine’s toolpath results from the surface’s analytic characterization. Asymptotic cutting and principal cutting are compared in terms of collisions and cutting error. We employed a general-purpose language (Java) to create machine instructions from the Weierstrass representation of minimal surfaces. Thus, the entire workflow from mathematical modeling to production involves no 3D models or CAD/CAM software. Both a 5-axis wire cutter and a customized robotic system were tested.

Two new polyketide metabolites, the 12-membered macrolides 4-hydroxy-12-methyloxacyclododecane-2,5,6-trione (1) and 12-methyloxacyclododecane-2,5,6-trione (2), were isolated from the endophytic fungal strain Cladosprium colocasiae A801 of the plant Callistemon viminalis, together with five known derivatives. Their structures were fully characterized by means of detailed spectroscopic analysis for new structures, and in comparison with published data for known compounds. The antibacterial, cytotoxic, and α-glucosidase inhibitory activities of the new compounds 1 and 2 were evaluated.

Sesquiterpene synthases are key enzymes for biosynthesis of sesquiterpene compounds and are important for agarwood formation in Aquilaria sinensis.The As-sesTPS gene encoding a novel sesquiterpene synthase was expressed in Escherichia coli strain BL21 (DE3) as an inclusion body and purified by Ni affinity chromatography. The molecular weight of the protein was lower than the theoretical value. Amino acid sequencing results indicated that the 27.2kDa-recombinant protein was a truncated sesquiterpene synthase from chemically induced A. sinensis. After refolding, the truncated As-SesTPS protein catalyzed the conversion of farnesyl pyrophosphate (FPP) to nerolidol which is a characteristic component of agarwood. The optimal reaction pH for the As-SesTPS protein was 8.0, and the optimal temperature was 30°C. The values of Km and Vmax of As-SesTPS protein towards FPP were 0.0548mM, 42.83μmol/mg.min, respectively. The results of qPCR and iTRAQ demonstrated the much higher expression level of As-SesTPS gene in agarwood than that in whitewood. This study provides a foundation for elucidating the mechanism of agarwood formation in A. sinensis and the potential of the novel gene for improving the quality of artificial agarwood.

High-energy-density enzymatic biofuel cells (EBFCs) are urgently needed not only as green energy conversion devices but also as energy generators for medical devices. Low enzyme loading efficiency and insufficient direct electron transfer (DET) between enzymes and electrodes greatly hamper the development of EBFCs. Herein, we fabricated nitrogen-doped hollow carbon nanospheres with large pores (pNHCSs) via a green microwave-assisted hydrothermal method (MWHM). Due to their three-dimensional structure and the incorporation of nitrogen, the pNHCS-functionalized electrode not only efficiently enriched the load of enzyme (ca. 8.65 × 10−10 mol cm−2) but also significantly facilitated DET rate (ca. 10.73 s−1). Thus, the pNHCS-based EBFCs exhibited an outstanding maximum power output (Pmax), which achieved to 325 ± 0.6 µW cm−2. Then, based on a dual-fuel-driven EBFC, we developed an innovative self-powered biosensor to sense two kinds of cancer-related microRNAs, miR-21 and miR-141, at the same time. The detection limits were as low as 0.1 fM for miR-21 and 4.0 fM for miR-141 (S/N = 3). This material has excellent potential in the development of superior green bio-batteries as well as economical and portable self-powered biomedical sensors.

Lithocarpins A–D (1–4), the first examples of highly oxygenated tenellone-macrolide conjugated dimers, were isolated from the deep-sea derived fungus Phomopsis lithocarpus FS508. Their structures were elucidated by extensive spectroscopic analyses and X-ray diffraction techniques. Their plausible biogenetic pathways suggested a very intriguing and unusual [4 + 2] cycloaddition with an isobenzofuran as an electron-donating diene. Lithocarpins C and D exhibited a moderate inhibitory effect against three tumor cell lines with IC50 values ranging from 17.0 to 21.6 μM.

The emergence of drug-resistant bacterial strains has challenged the use of traditional antibiotic therapies. Therefore, there is an urgent need to develop novel antibacterial materials or methods to effectively eradicate bacteria. Herein, we demonstrated a novel antibacterial system consisting of cupric oxide nanoparticles combined with ascorbic acid (CuO NPs/AA), which could act as a potent nanoantibiotic targeting both Escherichia coli (gram-negative) and Staphylococcus aureus (gram-positive) in vivo and in vitro, without noticeable cytotoxicity to mammalian tissue. The CuO NP/AA antibacterial system killed these microbes through a combined mechanism involving biofilm inhibition, cell membrane destruction, DNA damage, and enzyme inactivation. The antibacterial properties of CuO NPs/AA were mainly attributed to the generation of reactive oxygen species (e.g., ·OH) produced through the intrinsic ascorbate oxidase- and peroxidase-like activities of CuO NPs, highlighting their use as antibacterial nanozymes to treat bacterial infections.

A series hybrid variable flux memory (VFM) machine employing two kinds of permanent magnets (PMs) on alternate rotor poles is investigated. This VFM machine features controllable PM flux and thus good flux-weakening capability, as well as improved torque density. However, it is found that the unipolar end leakage flux occurs if the two kinds of PMs are not balanced. According to the analyses of series connection between two PMs based on the fundamental magnetic circuit, the mechanism of the unbalanced rotor poles and the unipolar end leakage flux is revealed. Further, the rule of obtaining balanced poles is identified and the effects of operating conditions are presented. A series hybrid VFM machine prototype is fabricated and tested.

Design of high-performance all-inorganic halide perovskites, especially lead-free perovskites, is key to the broadening of its application prospects. Herein, the authors report the synthesis of ligand-free cesium platinum (IV) bromide nanocrystals (Cs2 PtBr6 NCs), a new kind of vacancy-ordered lead-free perovskite nanomaterial, by a facile one-pot method. The Cs2 PtBr6 NCs exhibits a narrow band gap of 1.32 eV covering the entire visible range, which is supported by density functional theory calculations. Together with their high conductivity, matching energy levels with the work function of carbon electrodes, and excellent environmental stability, this NC displays a cathodic photocurrent density as high as 335 µA cm-2 , two orders of magnitude higher than other perovskites in aqueous solutions without the need of other electron acceptors. These combined properties suggest that the Cs2 PtBr6 NCs have great potentials in a wide range of photoelectronic and photoelectrochemical sensing applications.

Here, we fabricated N,S-Carbon (NSC) enfolded MnFe2O4 (MFO) nanospheres with abundant oxygen defects (OV), exploited as brilliant electrocatalyst for urea oxidation reaction (UOR) and hydrogen evolution reaction (HER). This typical nanoarchitecture possesses many characteristic compensations, (i) incorporation of OV in MFO to moderate the electronic arrangement for enhancing the electrons mobility and offering additional space for electrocatalysis and rapid absorption/diffusion of ions, (ii) homogeneously dispersed MFO nanospheres with great number of active sites and excellent catalytic activity, (iii) robust interaction between NSC and MFO ensuring the longstanding electrochemical stability, which are favorable to enhancing the kinetics of urea electrocatalysis. Electrochemical measurements proved NSC-MFO possesses outstanding UOR activity that shows a low potential of 1.42 V to attain 50 mA/cm2, too NSC-MFO contributes to excellent HER activity with low overpotential of 0.192 V to attain 50 mA/cm2. The excellent UOR performance of NSC-MFO authenticates could be wonderful applicant to replace OER to lower the cell potential thus decrease consumption of electrical energy for hydrogen-gas generation. As a proof of concept, overall urea splitting has been done with NSC-MFO as both cathode and anode, as-fabricated urea electrolytic cell offered 10 mA/cm2 at the cell voltage of 1.43 V with good durability for 15 h, displaying its potential practicability for energy-saving hydrogen making.

Assays for detecting tetanus toxoid are of great significance to be applied in the research of the safety testing of tetanus vaccine. Currently, guinea pigs or mice are usually used to evaluate the toxicity in these assays. Herein, a facile and quick biomineralization process was carried out to generate tetanus human immunoglobulin G (Tet-IgG)-functionalized Au nanoclusters (Tet-IgG-AuNCs). The obtained Tet-IgG-AuNCs exhibited strong red emission with a photoluminescence quantum yield of 13%. Based on surface plasmon resonance measurements, the apparent dissociation constant of the Tet-IgG-AuNC–tetanus toxoid complexes was measured to be 2.27 × 10−8 M. A facile detection approach was developed using a fluorescent Tet-IgG-AuNC–based immunochromatography test strip. By utilizing the high-brightness fluorescent Tet-IgG-AuNCs, this immunosensor showed favorable sensitivity with a detection limit at the level of 0.03 μg/mL. Further results demonstrated that this assay can reliably detect tetanus toxoid and therefore might provide a novel method to replace animal tests for the quantification of tetanus toxicity. Moreover, the antibody-AuNC-based immunochromatography test strip platform serves as a promising candidate to develop new approaches for detecting targeted antigens and biological events of interest.

A novel partitioned stator (PS) hybrid excited (HE) switched flux (SF) (PS-HESF) machine is proposed in this paper. In the PS-HESF machine, the permanent magnets (PMs) and field windings are allocated on one stator while the armature windings are placed on the other. The iron-piece-rotor is sandwiched between the two stators. Consequently, compared with the conventional HESF machine having PMs, field windings as well as armature windings all on one stator, the available space of the novel machine is greatly boosted and therefore the performance is enhanced. Based on 2-D finite-element analysis, the electromagnetic performance of the PS-HESF machine is evaluated and the results reveal that it can exhibit not only better flux regulation capability but also higher torque than the conventional HESF machine. Moreover, the influences of the key design parameters on the hybridization ratio in the PS-HESF machines are investigated. A prototype machine is manufactured and tested to validate the predictions.

In this work, bimetallic Bi/Pt nanoparticles in bovine serum albumin biomolecular scaffold (BSA-Bi/PtNPs) were synthesized through a facile and green method. As compared with BSA-PtNPs, the BSA-Bi/PtNPs possess enhanced peroxidase-like catalytic activity. Moreover, the BSA-Bi/PtNPs are stable in harsh conditions such as high temperature, extreme pH environments, and high ionic strength, as well as in common biological matrixes. These prominent advantages enable the BSA-Bi/PtNPs to be applied to a wide range of fields. Bioassays, such as serum glucose detection, extracellular hydrogen peroxide (H 2 O 2 ) monitor, and cancer cells labeling, have been realized with satisfying results. The linear range of glucose determination was from 1 to 100 μM and the limit of detection (LOD) was 0.2 μM. The H 2 O 2 released from each MCF-7 cell after stimulation was calculated to be 2.66 × 10 −16 mol/s. By utilizing folic acid as a recognition element, tumor cell could be readily distinguished by BSA-Bi/PtNPs and the LOD for MCF-7 cell detection was 90 cells.

Partitioned stator (PS) machines employ two separated stators to accommodate armature windings and permanent magnets (PMs), respectively, alleviating the space conflict in stator-PM machines, and hence boosting the torque density. However, the PM usage volume in PS machines is relatively large, and thus the material cost is high, which is undesirable for the cost-sensitive applications. In this paper, a PS machine employing ferrite PM is presented, which takes advantage of larger available space for PMs while balances the performance and cost. The electromagnetic characteristics of an optimized ferrite PS machine and an NdFeB PS machine are evaluated together with a classic Prius2010 interior PM (IPM) machine as a baseline. Meanwhile, the economic issues are considered. The results reveal that the NdFeB PS machine has higher torque density than the Prius2010 IPM machine, but is more expensive, while the ferrite PS machine can significantly reduce the cost and still exhibit good performance. The demagnetization behavior of the ferrite PS machine is evaluated and a new method to improve the demagnetization withstand capability is proposed. Moreover, the mechanical analysis is conducted for the cupped rotor of PS machines. Finally, a pair of small-scaled prototypes are manufactured to validate the predictions.