Comprehensive transcriptome and WGCNA analysis reveals the potential function of anthocyanins in low-temperature resistance of a red flower mutant tobacco.

The anthocyanin is a protective substance in various plants, and plays important roles in resisting to low-temperature. Here, we explored transcriptome analysis of pink flower (as CK) and the natural mutant red flower (as research objects) under low-temperature conditions, and aimed to reveal the potential functions of anthocyanins and anthocyanin-related regulatory factors in resistance to low-temperature. Our results showed that most of the differentially expressed genes (DEGs) encoding key enzymes in the late stage of anthocyanin metabolism in the mutant were significantly up-regulated. Meanwhile, several genes significantly differentially expressed in CK or mutant were obtained by classification and analysis of transcription factors (TFs), phytohormones and osmoregulators. Additionally, WGCNA was carried out to mine hub genes resistanted to low-temperature stress in flavonoid pathway. Finally, one UFGT family gene, three MYB and one bHLH were obtained as the future hub genes of this study. Combined with the above information, we concluded that the ability of the red flower mutant to grow and develop normally at low-temperatures was the result of a combination of flavonoids and cold resistance genes.

Genome-wide analysis of UDP-glycosyltransferases family and identification of UGT genes involved in abiotic stress and flavonol biosynthesis in Nicotiana tabacum.

BACKGROUND: Uridine disphosphate (UDP) glycosyltransferases (UGTs) act upon a huge variety of highly diverse and complex substrates, such as phytohormones and specialized metabolites, to regulate plant growth, development, disease resistance, and environmental interactions. However, a comprehensive investigation of UGT genes in tobacco has not been conducted. RESULTS: In this study, we carried out a genome-wide analysis of family-1 UDP glycosyltransferases in Nicotiana tabacum. We predicted 276 NtUGT genes, which were classified into 18 major phylogenetic subgroups. The NtUGT genes were invariably distributed among all the 24 chromosomes with structural diversity in exon/intron structure, conserved motifs, and cis-acting elements of promoters. Three groups of proteins which involved in flavonoid biosynthesis, plant growth and development, transportation and modification were identified that interact with NtUGT proteins using the PPI analysis. Expression analysis of NtUGT genes in cold stress, drought stress and different flower color using both online RNA-Seq data and the realtime PCR analysis, suggested the distinct role of NtUGT genes in resistance of cold, drought and in flavonoid biosynthesis. The enzymatic activities of seven NtUGT proteins that potentially involved in flavonoid glycosylation were analyzed, and found that all seven exhibited activity on myricetin; six (NtUGT108, NtUGT123, NtUGT141, NtUGT155, NtUGT179, and NtUGT195) showed activity on cyanidin; and three (NtUGT108, NtUGT195, and NtUGT217) were active on the flavonol aglycones kaempferol and quercetin, which catalyzing the substrates (myricetin, cyanidin or flavonol) to form new products. We further investigated the enzymatic products and enzymatic properties of NtUGT108, NtUGT195, and NtUGT217, suggested their diverse enzymatic activity toward flavonol, and NtUGT217 showed the highest catalyzed efficient toward quercetin. Overexpression of NtUGT217 significantly increase the content levels of the quercetin-3-O-glucoside, quercetin-3-O-rutinoside and kaempferol-3-O-rutinoside in transgenic tobacco leaves. CONCLUSION: We identified 276 UGT genes in Nicotiana tabacum. Our study uncovered valuable information about the phylogenetic structure, distribution, genomic characters, expression patterns and enzymatic activity of NtUGT genes in tobacco. We further identified three NtUGT genes involved in flavonoid biosynthesis, and overexpressed NtUGT217 to validate its function in catalyze quercetin. The results provide key candidate NtUGT genes for future breeding of cold and drought resistance and for potential metabolic engineering of flavonoid compounds.

Self-coordinated nanozyme on Cu3BiS3 nanorods for high-performance aptasensing.

A novel strategy is reported to access high-performance nanozymes via the self-coordination of ferrocyanides ([Fe(CN)6]4-) onto the surface of the Cu3BiS3 (CBS) nanorods. Notably, the in situ formed nanozymes had high catalytic activity, good stability, low cost, and easy mass production. The formed nanozyme catalyzed the oxidation of the typical chromogenic substrate of 3,3',5,5'-tetramethylbenzidine (TMB) with a distinctive absorption peak at 652 nm, accompanied by a blue color development. Moreover, the attachment of deoxyribonucleoside 5'-monophosphates (dNMP) beforehand onto the surface of CBS prevented coordination of ferrocyanides and resulted in the tunable formation of the nanozyme, thereby enabling the construction of an exquisite biosensing platform. Taking the aptasensing of chloramphenicol (CAP) as an example, the engineered nanozyme allowed the construction of a homogenous, label-free, and high-performance bioassay in terms of its convenience and high sensitivity. Under the optimal conditions, changes in the absorption intensity at 652 nm for the oxidized TMB provides a good linear correlation with the logarithm of CAP concentrations in the range 0.1 pM to 100 nM, and the limit of detection was 0.033 pM (calculated from 3σ/s). Considering a vast number of bioreactions can be connected to dNMP production, we expect the engineerable nanozyme as a universal signal transduction scaffold for versatile applications in bioassays. Through the attachment of deoxyribonucleoside 5'-monophosphate (dNMP) on the surface of CBS to regulate the generation of self-coordinated nanozyme CBS/BiHCF, a homogeneous, label-free, and high-performance universal aptasensing platform was constructed.

Invoking Cathodic Photoelectrochemistry through a Spontaneously Coordinated Electron Transporter: A Proof of Concept Toward Signal Transduction for Bioanalysis.

Most of the cathodic photoelectrochemical (PEC) bioassays rely on electron accepting molecules for signal stimuli; unfortunately, the performances of which are still undesirable. New signal transduction strategies are still highly expected for the further development of cathodic photoelectrochemistry as a potentially competitive method. This work represents a new concept of invoked cathodic photoelectrochemistry by a spontaneously formed electron transporter for innovative operation of the sensing strategy. Specifically, the hexacyanoferrate(II) in solution easily self-coordinated with CuO nanomaterials and formed electron transporting copper hexacyanoferrate (CuHCF) on the surface, which endowed improved carrier separation for presenting augmented photocurrent readout. Exemplified by the T4 polynucleotide kinase (T4 PNK) and its inhibitors as targets, a homogenous cathodic PEC biosensing platform was achieved with the distinctive merits of label-free, immobilization-free, and split-mode readout. The mechanism revealed here provided a totally different perspective for signal transduction in cathodic photoelectrochemistry. Hopefully, it may stimulate more interests in the design and construction of semiconductor/transporter counterparts for exquisite operation of photocathodic bioanalysis.

Microcystic pattern and shadowing are independent predictors of ovarian borderline tumors and cystadenofibromas in ultrasound.

OBJECTIVES: To determine the sonographic characteristics of borderline tumors (BoTs) and cystadenofibromas (CAFs). METHODS: Preoperative sonograms from consecutive patients who had at least one primary epithelial tumor in the adnexa were retrospectively collected. All tumors were described using the International Ovarian Tumor Analysis terminology. Ultrasound variables were tested using multinomial logistic regression after univariate analysis. RESULTS: A total of 650 patients were included in this study. Of these, 110 had a CAF, 128 had a BoT, 249 had a cystadenoma (CAD), and 163 had a cystadenocarcinoma (CAC). Nearly half of CAFs and more than half of BoTs and CACs appeared to be unilocular and multilocular solid on the ultrasound images, while CADs were predominantly uni- or multilocular (p < 0.001). Overall, shadowing was identified in 82/650 cases. Sixty-five of 110 (59.1%) CAFs exhibited an acoustic shadow, compared with only 4/249 (1.6%) in CADs, 7/128 (5.5%) in BoTs, and 6/163 (3.7%) in CACs (p < 0.001). Furthermore, 112/650 cases demonstrated microcystic pattern (MCP). Sixty-eight of 128 (53.1%) BoTs exhibited MCP, compared with only 5/249 (2.0%) in CADs, 19/163 (11.7%) in CACs, and 20/110 (18.2%) in CAFs (p < 0.001). Logistic regression analysis revealed that shadowing is an independent predictor of CAFs, while MCP is an independent predictor of BoTs. CONCLUSIONS: Sonographic findings for CAFs and BoTs were complex and partly overlapped with those for CACs. However, proper recognition and utilization of shadowing or MCP may help to correctly discriminate CAFs and BoTs. KEY POINTS: • Sonographic findings for borderline tumors and cystadenofibromas are complex and mimic malignancy. • Microcystic pattern and shadowing are independent predictors of borderline tumors and cystadenofibromas respectively.

Label-free and highly sensitive detection of DNA adenine methylation methyltransferase through cathodic photoelectrochemistry.

In this work, we report the first exploration of cathodic photoelectrochemistry for the determination of the activity of DNA adenine methylation (Dam) methyltransferase (MTase). In this sensing system, potassium ferricyanide (K3[Fe(CN)6]) can greatly stimulate the photocurrent of a CdS quantum dot (QD) sensitized NiO (NiO/CdS) photocathode. After immobilization of the hairpin DNA probe on the electrode surface, its high steric hindrance and the electrostatic repulsion block the access of K3[Fe(CN)6] to the electrode surface, leading to depressed photocurrent of the photocathode. Once the hairpin DNA probe is methylated by Dam MTase, it can be recognized and cleaved by Dpn I, and then further digested by (Exo I), ultimately leading to the removal of the hairpin DNA probe from the electrode surface. This configurational change induces the decrement of steric hindrance/electrostatic repulsion effects and allows the efficient flux of K3[Fe(CN)6] to the photoelectrode for photocurrent stimulation. The cathodic PEC assay is presented in the "turn-on" mode, which can detect Dam MTase in the linear range from 0.04 to 100 U mL-1, with a detection limit as low as 0.028 U mL-1. In principle, the platform presents a promising method for probing various biomolecules that can lead to configuration or charge variations at the electrode surface, which may become a general strategy for versatile targets.

Enantioselective separation and dissipation of pydiflumetofen enantiomers in grape and soil by supercritical fluid chromatography-tandem mass spectrometry.

Pydiflumetofen is registered in many countries and is widely used in crop production in the racemate form. However, the environmental behavior of the enantiomers has not been studied. An effective and sensitive chiral analytical method was first established for analyzing the pydiflumetofen enantiomers by supercritical fluid chromatography with tandem triple quadrupole mass spectrometry. The enantiomers could be separated and detected using the Chiralcel OD-3 column in less than 3 min. The separation conditions were as follows: mobile phase, CO2 /methanol (80:20); flow rate, 1.0 mL/min; column temperature, 30°C, auto back-pressure regulator pressure, 2000 psi with modified quick, easy, cheap, effective, rugged, and safe sample treatment method. The average recoveries of analytes from both matrices at three spiking levels were in the range of 84.1-103.0%. The limit of quantitation for each enantiomer was 0.005 mg/kg with a baseline resolution of approximately 1.64. The method was applied to monitor the enantioselective dissipation of pydiflumetofen in grape and soil. In grapes, (-)-pydiflumetofen was degraded more rapidly than (+)-pydiflumetofen. In soil, (+)-pydiflumetofen was preferentially degraded. The data provided useful references for the risk assessment and rational use of pydiflumetofen in agriculture.

Enantioseparation and dissipation monitoring of oxathiapiprolin in grape using supercritical fluid chromatography tandem mass spectrometry.

Oxathiapiprolin is a chiral fungicide used in China for the prevention and treatment of grape downy mildew, but its potential risk could be inaccurately assessed without distinguishing its enantiomers. In this study, an effective and sensitive chiral analytical method was first established for quantification of oxathiapiprolin enantiomers using supercritical fluid chromatography tandem mass spectrometry. Baseline separation for oxathiapiprolin enantiomers was achieved for less than 3 min by using a Lux Cellulose-2 chiral column with the resolution of 1.51. The elution order of the eluting enantiomers was identified as (-)-oxathiapiprolin and (+)-oxathiapiprolin by an optical rotation detector. The grape samples were extracted by QuEChERS method, with the average recoveries of each enantiomer in grapes were in the range of 88.1-111.8% and the relative standard deviations were less than 18.9%. The enantioselective analysis of the dissipation of oxathiapiprolin in field grape samples showed that (-)-oxathiapiprolin was dissipated faster than (+)-oxathiapiprolin. The results indicate that this proposed method could provide data support for the risk assessment of oxathiapiprolin in agricultural produces in a more accurate way.

A Novel Reverse Transcription Loop-Mediated Isothermal Amplification Method for Rapid Detection of SARS-CoV-2.

COVID-19 has become a major global public health burden, currently causing a rapidly growing number of infections and significant morbidity and mortality around the world. Early detection with fast and sensitive assays and timely intervention are crucial for interrupting the spread of the COVID-19 virus (SARS-CoV-2). Using a mismatch-tolerant amplification technique, we developed a simple, rapid, sensitive and visual reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for SARS-CoV-2 detection based on its N gene. The assay has a high specificity and sensitivity, and robust reproducibility, and its results can be monitored using a real-time PCR machine or visualized via colorimetric change from red to yellow. The limit of detection (LOD) of the assay is 118.6 copies of SARS-CoV-2 RNA per 25 µL reaction. The reaction can be completed within 30 min for real-time fluorescence monitoring, or 40 min for visual detection when the template input is more than 200 copies per 25 µL reaction. To evaluate the viability of the assay, a comparison between the RT-LAMP and a commercial RT-qPCR assay was made using 56 clinical samples. The SARS-CoV-2 RT-LAMP assay showed perfect agreement in detection with the RT-qPCR assay. The newly-developed SARS-CoV-2 RT-LAMP assay is a simple and rapid method for COVID-19 surveillance.

Targeting insect mitochondrial complex I for plant protection.

Plant engineered to express double-stranded RNA (dsRNA) can target the herbivorous insect gene for silencing. Although mounting evidence has emerged to support feasibility of this new pest control technology, field application is slow largely due to lack of potent targets. Here, we show that suppression of the gene encoding NDUFV2, a subunit of mitochondrial complex I that catalyses NADH dehydrogenation in respiratory chain, was highly lethal to insects. Feeding cotton bollworm (Helicoverpa armigera) larvae with transgenic cotton tissues expressing NDUFV2 dsRNA led to mortality up to 80% within 5 days, and almost no larvae survived after 7 days of feeding, due to the altered mitochondrial structure and activity. Transcriptome comparisons showed a drastic repression of dopa decarboxylase genes. Reciprocal assays with Asian corn borer (Ostrinia furnacalis), another lepidopteran species, revealed the sequence-specific effect of NDUFV2 suppression. Furthermore, the hemipteran lugus Apolygus lucorum was also liable to NDUFV2 repression. These data demonstrate that the mitochondrial complex I is a promising target with both sequence specificity and wide applicability for the development of new-generation insect-proof crops.

In Situ Enzymatically Generated Photoswitchable Oxidase Mimetics and Their Application for Colorimetric Detection of Glucose Oxidase.

In this study, a simple and amplified colorimetric assay is developed for the detection of the enzymatic activity of glucose oxidase (GOx) based on in situ formation of a photoswitchable oxidase mimetic of PO4(3-)-capped CdS quantum dots (QDs). GOx catalyzes the oxidation of 1-thio-ß-d-glucose to give 1-thio-ß-d-gluconic acid which spontaneously hydrolyzes to ß-d-gluconic acid and H2S; the generated H2S instantly reacts with Cd(2+) in the presence of Na3PO4 to give PO4(3-)-stabilized CdS QDs in situ. Under visible-light (λ ≥ 400 nm) stimulation, the PO4(3-)-capped CdS QDs are a new style of oxidase mimic derived by producing some active species, such as h⁺, (•)OH, O2(•-) and a little H2O2, which can oxidize the typical substrate (3,3,5,5-tetramethylbenzydine (TMB)) with a color change. Based on the GOx-triggered growth of the oxidase mimetics of PO4(3-)-capped CdS QDs in situ, we developed a simple and amplified colorimetric assay to probe the enzymatic activity of GOx. The proposed method allowed the detection of the enzymatic activity of GOx over the range from 25 µg/L to 50 mg/L with a low detection limit of 6.6 µg/L. We believe the PO4(3-)-capped CdS QDs generated in situ with photo-stimulated enzyme-mimicking activity may find wide potential applications in biosensors.

Versatile and Amplified Biosensing through Enzymatic Cascade Reaction by Coupling Alkaline Phosphatase in Situ Generation of Photoresponsive Nanozyme.

The alkaline phosphatase (ALP) biocatalysis followed by the in situ enzymatic generation of a visible light responsive nanozyme is coupled to elucidate a novel amplification strategy by enzymatic cascade reaction for versatile biosensing. The enzymatic hydrolysis of o-phosphonoxyphenol (OPP) to catechol (CA) by ALP is allowed to coordinate on the surface of TiO2 nanoparticles (NPs) due to the specificity and high affinity of enediol ligands to Ti(IV). Upon the stimuli by CA generated from ALP, the inert TiO2 NPs is activated, which demonstrates highly efficient oxidase mimicking activity for catalyzing the oxidation of the typical substrate of 3,3',5,5'-tetramethylbenzidine (TMB) under visible light (λ ≥ 400 nm) irradiation utilizing dissolved oxygen as an electron acceptor. On the basis of the cascade reaction of ALP and the nanozyme of CA coordinated TiO2 (TiO2-CA) NPs, we design exquisitely colorimetric biosensors for probing ALP activity and its inhibitor of 2, 4-dichlorophenoxyacetic acid (2,4-DA). Quantitative probing of ALP activity in a wide linear range from 0.01 to 150 U/L with the detection limit of 0.002 U/L is realized, which endows the methodology with sufficiently high sensitivity for potentially practical applications in real samples of human serum (ALP level of 40-190 U/L for adults). In addition, a novel immunoassay protocol by taking mouse IgG as an example is validated using the ALP/nanozyme cascade amplification reaction as the signal transducer. A low detection limit of 2.0 pg/mL is attained for mouse IgG, which is 4500-fold lower than that of the standard enzyme-linked immuno-sorbent assay (ELISA) kit. Although only mouse IgG is used as a proof-of-concept in our experiment, we believe that this approach is generalizable to be readily extended to other ELISA systems. This methodology opens a new horizon for amplified and versatile biosensing including probing ALP activity and following ALP-based ELISA immunoassays.

Using G-quadruplex/hemin to "switch-on" the cathodic photocurrent of p-type PbS quantum dots: toward a versatile platform for photoelectrochemical aptasensing.

We present a novel photoelectrochemical (PEC) biosensing platform by taking advantage of the phenomenon that hemin intercalated in G-quadruplex "switched-on" the cathode photocurrent of p-type PbS quantum dots (QDs). Photoinduced electron transfer between PbS QDs and G-quadruplex/hemin(III) complexes with the subsequent catalytic oxygen reduction by the reduced G-quadruplex/hemin(II) led to an obvious enhancement in the cathodic photocurrent of the PbS QDs. For the detection process, in the presence of hemin, the specific recognition of the targets with the sensing sequence would trigger the formation of a stable G-quadruplex/hemin complex, which will result in reduced charge recombination and hence amplified photocurrent intensity of the PbS QDs. By using different target sequences, the developed system made possible a novel, label-free "switch-on" PEC aptasensor toward versatile biomolecular targets such as DNA and thrombin. Especially, with ambient oxygen to regenerate G-quadruplex/hemin(II) to G-quadruplex/hemin(III), this substrate-free strategy not only promoted the photoelectric effect and thus the enhanced sensitivity of the system, but also avoided the addition of supplementary substrates of G-quadruplex/hemin such as H2O2 and organic substances.

Thioredoxin Reductase-Mediated Reaction Evokes In Situ Surface Polarization Effect on BiOIO3: Toward a New Sensing Strategy for Cathodic Photoelectrochemistry.

We have witnessed the fast progress of cathodic photoelectrochemistry over the past decades, though its signal transduction tactic still lacks diversity. Exploring new sensing strategies for cathodic photoelectrochemistry is extremely demanding yet hugely challenging. This article puts forward a unique idea to incorporate an enzymatic reaction-invoked surface polarization effect (SPE) on the surface of BiOIO3 to implement an innovative cathodic photoelectrochemical (PEC) bioanalysis. Specifically, the thioredoxin reductase (TrxR)-mediated reaction produced the polar glutathione (GSH), which spontaneously coordinated to the surface of BiOIO3 and induced SPE by forming a polarized electric field, resulting in improved electron (e-) and hole (h+) pair separation efficiency and an enhanced photocurrent output. Correlating this phenomenon with the detection of TrxR exhibited a high performance in terms of sensitivity and selectivity, achieving a linear range of 0.007-0.5 µM and a low detection limit of 2.0 nM (S/N = 3). This study brings refreshing inspiration for the cathodic PEC signal transduction tactic through enzyme-mediated in situ reaction to introduce SPE, which enriches the diversity of available signaling molecules. Moreover, this study unveils the potential of in situ generated SPE for extended and futuristic applications.

FHUSP-NET: A Multi-task model for fetal heart ultrasound standard plane recognition and key anatomical structures detection.

In prenatal ultrasound screening, rapid and accurate recognition of the fetal heart ultrasound standard planes(FHUSPs) can more objectively predict fetal heart growth. However, the small size and movement of the fetal heart make this process more difficult. Therefore, we design a deep learning-based FHUSP recognition network (FHUSP-NET), which can automatically recognize the five FHUSPs and detect tiny key anatomical structures at the same time. 3360 ultrasound images of five FHUSPs from 1300 mid-pregnancy pregnant women are included in this study. 10 fetal heart key anatomical structures are manually annotated by experts. We apply spatial pyramid pooling with a fully connected spatial pyramid convolution module to capture information about targets and scenes of different sizes as well as improve the perceptual ability and feature representation of the model. Additionally, we adopt the squeeze-and-excitation networks to improve the sensitivity of the model to the channel features. We also introduce a new loss function, the efficient IOU loss, which makes the model effective for optimizing similarity. The results demonstrate the superiority of FHUSP-NET in detecting fetal heart key anatomical structures and recognizing FHUSPs. In the detection task, the value of mAP@0.5, precision, and recall are 0.955, 0.958, and 0.931, respectively, while the accuracy reaches 0.964 in the recognition task. Furthermore, it takes only 13.6 ms to detect and recognize one FHUSP image. This method helps to improve ultrasonographers' quality control of the fetal heart ultrasound standard plane and aids in the identification of fetal heart structures in a less experienced group of physicians.

SEG-LUS: A novel ultrasound segmentation method for liver and its accessory structures based on muti-head self-attention.

Although liver ultrasound (US) is quick and convenient, it presents challenges due to patient variations. Previous research has predominantly focused on computer-aided diagnosis (CAD), particularly for disease analysis. However, characterizing liver US images is complex due to structural diversity and a limited number of samples. Normal liver US images are crucial, especially for standard section diagnosis. This study explicitly addresses Liver US standard sections (LUSS) and involves detailed labeling of eight anatomical structures. We propose SEG-LUS, a US image segmentation model for the liver and its accessory structures. In SEG-LUS, we have adopted the shifted windows feature encoder combined with the cross-attention mechanism to adapt to capturing image information at different scales and resolutions and address context mismatch and sample imbalance in the segmentation task. By introducing the UUF module, we achieve the perfect fusion of shallow and deep information, making the information retained by the network in the feature extraction process more comprehensive. We have improved the Focal Loss to tackle the imbalance of pixel-level distribution. The results show that the SEG-LUS model exhibits significant performance improvement, with mPA, mDice, mIOU, and mASD reaching 85.05%, 82.60%, 74.92%, and 0.31, respectively. Compared with seven state-of-the-art semantic segmentation methods, the mPA improves by 5.32%. SEG-LUS is positioned to serve as a crucial reference for research in computer-aided modeling using liver US images, thereby advancing the field of US medicine research.

Benchmarking Supervised and Self-Supervised Learning Methods in A Large Ultrasound Muti-task Images Dataset.

Deep learning in ultrasound(US) imaging aims to construct foundational models that accurately reflect the modality's unique characteristics. Nevertheless, the limited datasets and narrow task types have restricted this field in recent years. To address these challenges, we introduce US-MTD120K, a multi-task ultrasound dataset with 120,354 real-world two-dimensional images. This dataset covers three standard plane recognition and two diagnostic tasks in ultrasound imaging, providing a rich basis for model training and evaluation. We detail the data collection, distribution, and labelling processes, ensuring a thorough understanding of the dataset's structure. Furthermore, we conduct extensive benchmark tests on 27 state-of-the-art methods from both supervised and self-supervised learning(SSL) perspectives. In the realm of supervised learning, we analyze the sensitivity of two main feature computation methods to ultrasound images at the representational level, highlighting that models which judiciously constrain global feature computation could potentially serve as a viable analytical approach for US image analysis. In the context of self-supervised learning, we delved into the modelling process of self-supervised learning models for medical images and proposed an improvement strategy, named MoCo-US, a solution that addresses the excessive reliance on pretext task design from the input side. It achieves competitive performance with minimal pretext task design and enhances other SSL methods simply. The dataset and the code will be available at https://github.com/JsongZhang/CDOA-for-UMTD.

Kanamycin triggered nanozyme for homogeneous and amplified colorimetric detection of T4 polynucleotide kinase.

It is of significance to develop efficient methods for detecting the activity of T4 polynucleotide kinase (T4 PNK) due to its essential role in the modulation of different life activities. In this work, we constructed a novel nanozyme using Kanamycin (KANA) as a trigger for the [Fe(CN)6]3- coordinated Cu2(OH)3NO3 (Cu2(OH)3NO3/[Fe(CN)6]3-) nanorods, and designed an amplified colorimetric method to detect T4 PNK. That was, the free KANA efficiently triggered the peroxidase-like activity of Cu2(OH)3NO3/[Fe(CN)6]3-, while the bound KANA by its aptamer lost the stimulative capability for the nanomaterials. On the basis of the bioreaction regulated generation of the KANA aptamer, a highly sensitive colorimetric assay aided by the rolling circle amplification (RCA) reaction for the detection of T4 PNK was realized. Results showed that this assay can detect T4 PNK from 1.0 × 10-3 to 10.0 U/mL, with a limit of detection (LOD) of 1.42 × 10-4 U/mL. The assay also showed acceptable performance in the detection of T4 PNK in serum samples. In addition to the satisfactory sensitivity and selectivity, the displayed T4 PNK assay also presented merits of operational convenience, without labeling or immobilization process and did not require costly instrument. It is expected that the KANA as a stimulator would have extended biosensing applications by coupling various bioreactions that can produce the KANA aptamer.

In situ formed and switchable enzymatic activity of BiOBr under light stimulation for homogeneous and label-free bioassay.

A new concept to construct photoresponsive nanozyme through the in situ deposition of electron transporting material (ETM) on BiOBr nanoplates was proposed. That was, the spontaneous coordination of ferricyanide ions (i.e., [Fe(CN)6]3-) onto the surface of BiOBr formed electron transporting material (ETM), which efficiently prevented electron-hole recombination and led to efficient enzyme mimicking activity under light stimuli. Moreover, the formation of the photoresponsive nanozyme was regulated by pyrophosphate ions (PPi) due to the competitive coordination of PPi with [Fe(CN)6]3- onto the surface of BiOBr. This phenomenon allowed the construction of an engineerable photoresponsive nanozyme that was coupled with the rolling circle amplification (RCA) reaction to elucidate a novel bioassay for chloramphenicol (CAP, taken as a model analyte). The developed bioassay manifested the merits of label-free, immobilization-free and with efficiently amplified signal. Quantitative analysis of CAP in a wide linear range from 0.05 to 100 nM with the detection limit of 0.015 nM was realized, which endowed the methodology with sufficiently high sensitivity. It is expected to be a powerful signal probe in bioanalytical field by virtue of its switchable and fascinating visible-light-induced enzyme mimicking activity.