Incidence, Predictors, and Implications of Secondary Aortic Intervention Following Thoracic Endovascular Aortic Repair for Type B Dissection.

BACKGROUND: Secondary aortic intervention (SAI) following thoracic endovascular aortic repair (TEVAR) is not uncommon. However, a satisfactory management system has not been established for these patients. We aimed to report our single-center experience with SAI after prior TEVAR for type B aortic dissection (TBAD). METHODS: From January 2010 to May 2017, 860 eligible patients with TBAD underwent TEVAR. One hundred seven (12.4%) patients required SAI, either endovascularly (n=76) or surgically (n=31). The main indications for SAI were entry flow (n=58 [54.2%]), aneurysm expansion of the proximal or remote aorta (n=26 [24.3%]), retrograde type A aortic dissection (n=11 [10.3%]), distal stent-graft-induced new entry tear (n=6 [5.6%]), and stent migration (n=4 [3.7%]). The Kaplan-Meier curves were generated to determine the degree of freedom from SAI and the prognosis. Cox proportional hazards were used to screen for risk factors for SAI and poor prognosis. RESULTS: The overall 30-day mortality rate after SAI was 4.7% (n=5): endovascular (n=2 [2.6%]) vs open surgery (n=3 [9.7%]; p=0.145). The cumulative survival rates with or without SAI were 86.3%±3.6% vs 95.7%±0.8% at 3 years and 82.0%±4.2% vs 92.2%±1.1% at 5 years, respectively (log-rank p<0.001). Although no significant difference in survival was observed, the incidence of SAI was significantly greater in patients who underwent TEVAR during the chronic phase (acute [11.6%] vs subacute [9.6%] vs chronic [27.8]; p<0.001). Multivariate regression analysis revealed that prior TEVAR in the chronic phase (hazard ratio [HR]=1.73, 95% confidence interval [CI]=1.03-2.90; p=0.039), maximum aortic diameter (HR=1.05, 95% CI=1.04-1.07; p<0.001), and arch involvement (HR=1.48, 95% CI=1.01-2.18; p=0.048) were predictors of the incidence of SAI. In addition, the maximum aortic diameter was demonstrated to be the only risk factor for prognosis after adjusting for confounding factors. CONCLUSIONS: Thoracic endovascular aortic repair for chronic TBAD patients should be reconsidered. Open surgery is preferable for those with proximal progression, whereas endovascular treatment is more suitable for distal lesions. Close surveillance and timely reintervention after TEVAR, whether via endovascular techniques or open surgery, are necessary to prevent devastating complications. CLINICAL IMPACT: The management of patients with type B aortic dissection (TBAD) after thoracic endovascular aortic repair (TEVAR) is challenging. We summarized our single-center experience regarding secondary aortic intervention after TEVAR for TBAD. We found that TEVAR for chronic TBAD patients should be carefully evaulated, and open surgery is recommended for those with proximal progession, while endovascular treatment is more preferable for distal lesions.

Visual Sensor Arrays for Distinction of Phenolic Acids Based on Two Single-Atom Nanozymes.

Although great achievements have been made in the study of artificial enzymes, the design of nanozymes with high catalytic activities of natural enzymes and the further establishment of sensitive biosensors still remain challenging. Here, two nanozymes, i.e., ZnCoFe three-atom nanozyme (TAzyme) and Sn single-atom nanozyme (SAzyme)/Ti3C2Tx, are developed, which show peroxidase-like catalytic activities by catalyzing the reaction of hydrogen peroxide (H2O2), 4-aminoantipyrine (4-AAP), and phenolic acids to generate colorimetric reactions. The involvement of different phenolic acids leads to the generation of different color products. These subtle color-variation profiles between these phenolic acids prompt us to exploit an electronic tongue based on the two nanozymes to distinguish phenolic acids. Data interpretation by the pattern recognition method, such as linear discriminant analysis (LDA), displays good clustering separation of six different phenolic acids at concentrations of 0.1 µM to 1 mM, validating the effectiveness of the colorimetric nanozyme sensor array.

Peroxidase-Like FeCoZn Triple-Atom Catalyst-Based Electronic Tongue for Colorimetric Discrimination of Food Preservatives.

Recently, single-atom catalysts are attracting much attention in sensor field due to their remarkable peroxidase- or oxidase-like activities. Herein, peroxidase-like FeCoZn triple-atom catalyst supported on S- and N-doped carbon derived from ZIF-8 (FeCoZn-TAC/SNC) serves as a proof-of-concept nanozyme. In this paper, a dual-channel nanozyme-based colorimetric sensor array is presented for identifying seven preservatives in food. Further experiments reveal that the peroxidase-like activity of the FeCoZn TAzyme enables it to catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) and o-phenylenediamine (OPD) in the presence of H2 O2 , yielding the blue oxTMB and yellow oxOPD, respectively. However, food preservatives are adsorbed on the nanozyme surface through π-π stacking interaction and hydrogen bond, and the reduction in catalytic activity of FeCoZn TAzyme causes differential colorimetric signal variations, which provide unique "fingerprints" for each food preservative.

Colorimetric identification of multiple terpenoids based on bimetallic FeCu/NPCs nanozymes.

Nanozymes have been relatively well explored, and bimetal-doped nanozymes have attracted much exploration due to their superior catalytic activity. We developed bimetallic FeCu/NPCs and Cu/NPCs nanozymes, which have good catalytic properties due to the coordination of Fe and Cu with N and P. The nanozymes acted as sensing elements in a cascade reaction system to effectively recognize seven terpenoids, including menthol (Men), paeoniflorin (Pae), camphor (Cam), paclitaxel (Pac), andrographolide (Andro), ginkgolide A (Gin A), and piperone (Pip). Terpenoids act as inhibitors of acetylcholinesterase (AChE) and reduce the hydrolysis of acetylcholine (ATCh), providing insight into establishing a simple and distinct assay for terpenoids. Notably, the sensor array distinguished seven terpenoids with concentrations as low as 10 ng/mL and achieved high-precision detection of mixed samples with different molar ratios and 21 unknown samples. Finally, the sensor array successfully distinguished and identified multiple terpenoids in herbal samples.

Cancer-Associated Fibroblast Risk Model for Prediction of Colorectal Carcinoma Prognosis and Therapeutic Responses.

Colorectal carcinoma (CRC) is a malignant tumor of the digestive system. Cancer-associated fibroblasts (CAFs) are important cellular elements in the tumor microenvironment of CRC, which contribute to CRC progression and immune escape. To predict the survival outcome and therapeutic responses of CRC patients, we identified genes connected with stromal CAF and generated a risk model. In this study, we used multiple algorithms to reveal CAF-related genes in the Gene Expression Omnibus and The Cancer Genome Atlas datasets and construct a risk model composed by prognostic CAF-associated genes. Then, we evaluated whether the risk score could predict CAF infiltrations and immunotherapy in CRC and confirmed the expression of the risk model in CAFs. Our results showed that CRC patients with high CAF infiltrations and stromal score had worse prognosis than those with low-CAF infiltrations and stromal score. We obtained 88 stromal CAF-associated hub-genes and generated a CAF risk model consisting of ZNF532 and COLEC12. Compared with low-risk group, the overall survival in high-risk group was shorter. The relationship between risk score, ZNF532 and COLEC12, and stromal CAF infiltrations and CAF markers was positive. In addition, the effect of immunotherapy in the high-risk group was not as good as that in the low-risk group. Patients with the high-risk group were enriched in chemokine signaling pathway, cytokine-cytokine receptor interaction, and focal adhesion. Finally, we confirmed that the expressions of ZNF532 and COLEC12 in risk model were widely distributed in fibroblasts of CRC, and the expression levels were higher in fibroblasts than CRC cells. In conclusion, the prognostic CAF signature of ZNF532 and COLEC12 can be applied not only to predict the prognosis of CRC patients but also to evaluate the immunotherapy response in CRC patients, and these findings provide the possibility for further development of individualized treatment for CRC.

Effects of Home-based Remote Cardiac Rehabilitation on Left Ventricular Function and Fear of Exercise in Patients after Percutaneous Coronary Intervention (PCI): A Retrospective Cohort Study.

AIM: This study aims to explore the effects of home-based remote cardiac rehabilitation on left ventricular function and exercise fear in patients after percutaneous coronary intervention (PCI). METHODS: A total of 232 patients with coronary heart disease after PCI treated in Tianshan Traditional Chinese Medicine Hospital from January 2020 to December 2022 were retrospectively analyzed. The patients were divided into the remote rehabilitation group (169 cases) and the routine group (63 cases) according to the exposure factor (home-based remote cardiac rehabilitation). Changes in left ventricular function and sports phobia Tampa Scale in patients with coronary heart disease after PCI were compared using propensity score matching to reduce selection bias and confounding factors. RESULTS: After the intervention, the scores of patients in the tele-rehabilitation group were significantly higher than those in the conventional group in terms of fear of movement, perception of danger, fear of movement, avoidance of movement, and dysfunction (p-value < 0.05). Left heart function was compared between the tele-rehabilitation group and the conventional group. Patients in the tele-rehabilitation group had significantly higher peak mitral valve blood flow in the early diastolic period (E), peak mitral valve blood flow in the late diastolic period (A), six-minute walk test (6MWT), and ratio of the peak mitral valve blood flow in the early diastolic period to the peak mitral valve blood flow in the late diastolic period (E/A) than those in the conventional group (p-value < 0.05). However, the peak deceleration time and isovolumic diastolic time in the early mitral valve diastolic period were significantly higher in the tele-rehabilitation group than in the conventional group (p-value < 0.05). CONCLUSIONS: Home-based remote cardiac rehabilitation instruction can improve the heart function and exercise fear state of patients after PCI.

A dual-channel sensor array for discrimination of biothiols based on manganese dioxide nanosheets.

A dual-signal sensor array for highly sensitive identification of biothiols is reported based on different optical responses of MnO2/curcumin (CUR) system to different biothiols. The addition of MnO2 nanosheets (MnO2 NSs) quenches the fluorescence of CUR, and the color of the mixture changes from yellow to brown. In the presence of reductive biothiols, MnO2 NSs are etched and lose their fluorescence quenching ability, resulting in an increase in the fluorescence intensity of CUR at 540 nm and a decrease in the absorbance at 430 nm. The sensor array generates specific response modes based on the varying reduction abilities of different biothiols, which can be distinguished by linear discriminant analysis (LDA). The sensor array successfully distinguished five biothiols (glutathione (GSH), dithiothreitol (DTT), cysteine (Cys), mercaptoethanol (ME), and homocysteine (Hcy)) across a wide concentration range (1 µM-100 µM) and biothiol mixtures with varing molar ratios.

CsPbBr3 and CsPbBr3/SiO2 Nanocrystals as a Fluorescence Sensing Platform for High-Throughput Identification of Multiple Thiophene Sulfides.

Air pollution is a serious problem. Refractory thiophene sulfides, which cause air pollution, bring great challenges to their rapid and accurate identification. In this work, we propose a fluorescent sensor array based on two perovskite nanocrystals (CsPbBr3 NCs and CsPbBr3/SiO2 NCs) to distinguish different thiophene sulfides. The hydrogen bonding force between the thiophenics of thiophene sulfides and the amino groups of the perovskite NCs results in the weakening of the fluorescence signals of the perovskite NCs. The diverse interactions between thiophene sulfides and two perovskite NCs provide rich information, which can be obtained on the sensor array and identified by linear discriminant analysis. Five thiophene sulfides (i.e., benzothiophene, dibenzothiophene, 2-methylbenzothiophene, 3-methylthiophene, and thiophene) were discriminated by the sensor array at concentrations of 10-50 ppm. The effectiveness of the sensor array was further verified in the discrimination of blinded samples, in which all 10 samples were correctly identified. In addition, it is gratifying that even binary mixtures of thiophene sulfides could be distinguished by the proposed sensor array.

Oxidase-like ZnCoFe Three-Atom Nanozyme as a Colorimetric Platform for Ascorbic Acid Sensing.

Great enthusiasm in single-atom catalysts for various catalytic reactions continues to heat up. However, the poor activity of the existing single/dual-metal-atom catalysts does not meet the actual requirement. In this scenario, the precise design of triple-metal-atom catalysts is vital but still challenging. Here, a triple-atom site catalyst of FeCoZn catalyst coordinated with S and N, which is doped in the carbon matrix (named FeCoZn-TAC/SNC), is designed. The FeCoZn catalyst can mimic the activity of oxidase by activating O2 into •O2- radicals by virtue of its atomically dispersed metal active sites. Employing this characteristic, triple-atom catalysts can become a great driving force for the development of novel biosensors featuring adequate sensitivity. First, the property of FeCoZn catalyst as an oxidase-like nanozyme was explored. The obtained FeCoZn-TAC/SNC shows remarkably enhanced catalytic performance than that of FeCoZn-TAC/NC and single/dual-atom site catalysts (FeZn, CoZn, FeCo-DAC/NC and Fe, Zn, Co-SAC/NC) because of trimetallic sites, demonstrating the synergistic effect. Further, the utility of the oxidase-like FeCoZn-TAC/SNC in biosensor field is evaluated by the colorimetric sensing of ascorbic acid. The nanozyme sensor shows a wide concentration range from 0.01 to 90 µM and an excellent detection limit of 6.24 nM. The applicability of the nanozyme sensor in biologically relevant detection was further proved in serum. The implementation of TAC in colorimetric detection holds vast promise for further development of biomedical research and clinical diagnosis.

High throughput sensing of multiple amino acids with differential pulse voltammetry measurement.

The content of amino acids in human body is closely related to human health and plays an important role in physiological regulation and medical function. In order to recognize a variety of amino acids, an electrochemical sensor array based on poly(3,4-ethylenedioxythiophene) (PEDOT) electrode was established by using two kinds of electropolymerizers, i.e., citrate and the mixture of citrate and potassium nitrate as sensing elements. Different electropolymerizers lead result in different amount of negative charge on PEDOT electrode, which leads to different adsorption capacity for positive charge amino acids and different repulsion capacity for negative charge amino acids, bringing about obvious changes in differential pulse voltammetry (DPV) current. The five amino acids were accurately identified by linear discriminant analysis (LDA), and the electrochemical sensor array was successfully applied in the differential detection of amino acids in milk.

A colorimetric sensor array for rapid discrimination of edible oil species based on a halogen ion exchange reaction between CsPbBr3 and iodide.

Peroxides in edible oils, whose amounts are measured using the peroxide value, are closely related to human health. Long-term consumption of edible oils with high peroxide values can lead to a variety of human diseases, which highlights the significance of examining oil types and their corresponding peroxide values. For identifying a wide range of edible oils, we established a colorimetric sensor array based on the halogen ion exchange between CsPbBr3 and two iodides (octadecylammonium iodide (ODAI) and ZnI2). Different kinds of edible oils contain distinct peroxidic substances that have the distinct ability to oxidize iodides. After specific types of edible oils react with excess iodides (ODAI and ZnI2), different amounts of residual iodides are left for further halogen exchange with CsPbBr3, resulting in various colorimetric responses, measured in RGB (red/green/blue) values, under fluorescent light. Based on RGB pattern analysis as fingerprints using two anion exchangers (ODAI and ZnI2), our proposed colorimetric sensor array was proved by linear discriminant analysis (LDA) to have an ability to accurately distinguish edible oils at a minimal volumetric concentration of 6.67% in seven real samples.

Colorimetric sensing strategy for detection of cysteine, phenol cysteine, and phenol based on synergistic doping of multiple heteroatoms into sponge-like Fe/NPC nanozymes.

Nanozymes have both the high catalytic activity of natural enzymes and the stability and economy of mimetic enzymes. Research on nanozymes is rapidly emerging, and the continuous development of highly catalytic active nanozymes is of far-reaching significance. This work reports heteroatomic nitrogen (N) and phosphorus (P) double-doped mesoporous carbon structures and metallic Fe coordination generated sponge-like nanozymes (Fe/NPCs) with good peroxidase activity. On this basis, we constructed a highly sensitive colorimetric sensor with cysteine and phenol as simulated analytes using Fe/NPCs nanozymes, and the response limits reached 53.6 nM and 5.4 nM, respectively. Besides, the method has high accuracy in the detection of cysteine and phenol at low concentrations in serum and tap water, which lays a foundation for application in the fields of environmental protection and biosensors.

Innovative Electrochemical Sensor Using TiO2 Nanomaterials to Detect Phosphopeptides.

Many enrichment techniques for phosphopeptides usually rely on the interaction of phosphate groups with metal ions or metal oxides. Based on this, we innovatively designed and fabricated an electrochemical sensor based on TiO2 nanoparticles (NPs), which can sensitively and rapidly detect phosphopeptides in protein samples pretreated with AuNPs. When the phosphopeptide solution was pretreated with AuNPs, AuNPs can be linked to the polypeptide chain via the amino group at the tail of the polypeptide chain. When TiO2 NPs are specifically bound to the phosphate group on the peptide, the modified AuNPs can improve the electron conduction ability of the electrode to detect the phosphopeptides. The designed electrochemical sensor had the advantages of high sensitivity, selectivity, and repeatability, and it showed a wide linear concentration range (1 pg/L to 1 mg/L) and a lower limit of detection (0.24 pg/L) for phosphopeptides. In order to improve the detection capability of the electrochemical sensor, we also synthesized TiO2 and graphene oxide (GO) composite materials. The influence of the morphology and crystal form of TiO2 NPs on phosphopeptide detection was studied by changing the feeding ratio and heat treatment temperature. We found that the uniformly dispersed anatase crystal TiO2 and GO composite-modified electrode showed a lower detection limit (0.37 ag/L). This sensing strategy is expected to provide a novel solution for the direct detection of phosphate groups in polypeptides in complex environments.

Visual detection of multiple antioxidants based on three chloroauric acid/Au-Ag nanocubes.

A colorimetric sensing method is described for discrimination of multiple antioxidants based on core-shell Au@Ag nanocubes (NCs). In order to extract data-rich colorimetric responses from the sensor array, three different concentrations of chloroaurate acid (HAuCl4) were employed as sensing elements. Interestingly, Au3+ ions can be reduced to different valence states (i.e., Au(0) and Au(I)) by different antioxidants, and thus effectively inhibit the oxidation etching process of Au@Ag NCs by Au(III) ions to varying extents, generating diverse colorimetric responses (color and absorbance). This enables identification of the six antioxidants at 10 nM via linear discriminant analysis (LDA) with relative standard deviation (RSD) of 2.52% (n = 3). The discrimination ability of the sensor array was further evaluated in antioxidant binary and multicomponent mixtures. Remarkably, identification of these six antioxidants spiked in urine was realized with 100% of accuracy. Schematic presentation of colorimetric assay for antioxidants based on three chloroauric acid/Au-Ag nanocubes.

New application of a traditional method: colorimetric sensor array for reducing sugars based on the in-situ formation of core-shell gold nanorod-coated silver nanoparticles by the traditional Tollens reaction.

An effective and robust colorimetric sensor array for simultaneous detection and discrimination of five reducing sugars (i.e., glyceraldehyde (Gly), fructose (Fru), glucose (Glu), maltose (Mal), and ribose (Rib)) has been proposed. In the sensor array, two negatively charged polydielectrics (sodium polystyrenesulfonate (NaPSS) and sodium polymethacrylate (NaPMAA)), which served as the sensing elements, were individually absorbed on the surface of the cetyltrimethylammonium bromide (CTAB)-coated gold nanorods (AuNR) with positive charges through electrostatic action, forming the designed sensor units (NaPSS-AuNR and NaPMAA-AuNR). In the presence of Tollens reagent (Ag(NH3)2OH), Ag+ was absorbed on the surface of negatively charged NaPSS-AuNR and NaPMAA-AuNRs. When confronted with differential reducing sugars, different reducing sugars exhibited differential levels of deoxidizing abilities toward Ag+, thus Ag+ was reduced to diverse amounts of silver nanoparticles (AgNPs) in situ to form core-shell AuNR@AgNP by the traditional Tollens reaction method, leading to distinct colorimetric response patterns (value of AS/AL (the ratio of absorbance at 360 nm to that at 760 nm in Ag+-NaPMAA-AuNR, and the ratio of absorbance at 360 nm to that at 740 nm in Ag+-NaPSS-AuNR)). These response patterns are characteristic for each reducing sugar, and can be quantitatively distinguished by linear discriminant analysis (LDA) at concentrations as low as 10 nM with relative standard deviation (RSD) of 4.11% (n = 3). The practicability of this sensor array has been validated by recognition of reducing sugars in serum and urine samples. A colorimetric sensor array for reducing sugar discrimination based on the reduction of Ag+ and in situ formation of AuNR@AgNP.

A rapid reduction of Au(I→0) strategy for the colorimetric detection and discrimination of proteins.

A gold nanoparticle (AuNP)-based sensing strategy based on rapid reduction of Au(I→0) is proposed. As a proof-of-concept study, the proposed sensing principle is designed for simultaneous and colorimetric detection and discrimination of multiple proteins. In the presence of H2O2, the target proteins could reduce Au(I) (i.e. HAuCl2) to AuNPs with different sizes, shapes and dispersion/aggregation states, thus resulting in rapidly colorimetric identification of different proteins. The optical response (i.e. color) of AuNPs is found to be characteristic of a given protein. The color response patterns are characteristic for each protein and can be quantitatively differentiated by statistical techniques. The sensor array is capable of discriminating proteins at concentrations as low as 0.1 µg/mL with high accuracy. A linear relationship was observed between the total Euclidean distances and protein concentration, providing the potential for protein quantification using this sensor array. The limit of detection (LOD) for catalase (Cat) is 0.08 µg/mL. The good linear range (from 0 to 8 µg/mL) has been used for the quantitative assay of Cat. To show a potentially practical application, this method was used to detect and discriminate proteins in human urine and tear samples. Graphical abstract We report a facile gold nanoparticle (AuNP)-based sensing strategy, that is, "a rapid reduction of Au(I) to Au(0) nanoparticles with different sizes and shapes by analytes that having certain reducing capabilities, resulting in different colours." The proposed sensing principle is designed for simultaneous, colorimetric detection and discrimination of multiple proteins.

Colorimetric Differentiation of Multiple Oxidizing Anions Based on Two Core-Shell Au@Ag Nanoparticles with Different Morphologies as Array Recognition Elements.

The efficient discrimination of oxidizing anions is of considerable importance in environmental monitoring. Here, for the first time, we have developed a simple and fast colorimetric sensor array for detection and identification of oxidizing anions, which takes advantage of the etching of the Ag shell of two core-shell Au@Ag nanoparticles (Au@Ag nanospheres (Au@Ag NPs) and Au@Ag nanocubes (Au@Ag NCs)) by oxidizing anions. The differential etching ability of various oxidizing anions to the Ag shell of the two Au@Ag nanoparticles resulted in different absorbance and color change of the nanoparticles. Thus, employing Au@Ag NPs and Au@Ag NCs as the array's receptors and the indicators, six oxidizing anions (i.e., BrO3-, Cr2O72-, ClO4-, IO3-, IO4-, and MnO4-) down to 10 nM could be identified from each other by their own colorimetric response patterns. Moreover, the complex mixtures of oxidizing anions could be well discriminated. Most importantly, the sensor array was successfully applied to the discrimination of oxidizing anions in river water and tap water samples.

Colorimetric Differentiation of Flavonoids Based on Effective Reactivation of Acetylcholinesterase Induced by Different Affnities between Flavonoids and Metal Ions.

Flavonoids are closely related to human health, and the distinguishiment of flavonoids is an important but difficult issue. We herein unveil a novel colorimetric sensor array for the rapid identification of 7 flavonoids (e.g., gallocatechin (GC), morin hydrate (MH), puerarin (Pu), epigallocatechin gallate (EGCG), catechin (C), rac Naringenin (rN), and Flavone (Fla)) for the first time. The colorimetric performances of gold nanoparticles (AuNPs) are characteristically correlated with thiocholine, which is issued from the enzymatic hydrolysis of acetylcholine (AcCh). Therefore, as a proof-of-concept design, three sensors (Cu2+/acetylcholinesterase (AcChE)/AcCh/AuNPs, Zn2+/AcChE/AcCh/AuNPs, and Mn2+/AcChE/AcCh/AuNPs) were constructed to form our sensor array. The distinct affinities between flavonoids and metal ions would cause varying degrees of effective reactivation of AcChE, leading to unique colorimetric response patterns upon being challenged with the seven flavonoids for their pattern recognition, enabling an excellent identification of the seven flavonoids at a concentration of 20 nM and different concentrations of individual flavonoids, as well as mixtures of them.

Colorimetric identification of lanthanide ions based on two carboxylic acids as an artificial tongue.

We report a colorimetric array, which consists of two carboxylic acids (quinolinic acid (QA), tannic acid (TCA)) as the sensor element and Eriochrome Black T (EBT) as the colorimetric signal readout. The assay is based on coordination binding between lanthanide ions and EBT, and between lanthanide ions and the carboxylic acids. The competitive binding of lanthanide ions with the carboxylic acids and EBT leads to the change in absorbance and color of the solutions. To test the efficacy of our sensor array, the sensor array was exposed to five target lanthanide ions (La3+, Sm3+, Eu3+, Gd3+ and Yb3+) with diverse concentrations (10, 50, 100, 200, 300, 400, and 500 nM). Linear discriminant analysis (LDA) results show that the sensor array can identify the five lanthanide ions, with a low discrimination limit of 10 nM. More importantly, the sensor array realizes fast discrimination of lanthanide ions in river samples, showing potential in environmental monitoring.

Colorimetric discriminatory array for detection and discrimination of antioxidants based on HAuCl4/3,3',5,5'-tetramethylbenzidine.

Here, we report a simple but effective nose/tongue-mimic sensor array based on HAuCl4/3,3',5,5'-tetramethylbenzidine (TMB) for colorimetric discrimination and determination of antioxidants. Two concentrations of HAuCl4 were employed as receptor units to construct the colorimetric sensor array. The sensing strategy is based on the fact that HAuCl4 with different concentrations (0.08 and 0.03 mM) could oxidize TMB to oxidized TMB (oxTMB), resulting in a blue and green color solution, respectively, corresponding to an absorption peak centered at 440 nm and 657 nm. However, the presence of different antioxidants could cause the reduction in HAuCl4, leading to the fading of the blue and green color and the decrease in the absorbance at 440 nm and 657 nm to varying degrees. Based on the above phenomena, by taking advantage of linear discriminant analysis (LDA), five antioxidants (i.e. ascorbic acid (AA), melatonin (MT), uric acid (UA), tannic acid (TCA), and glycine (Gly)) at five concentrations (200, 120, 60, 20, and 1 nM) were successfully discriminated both in buffer and serum. More importantly, this approach is simple, fast, and without the use of any nanomaterials.