Di-Isatropolone C, a Spontaneous Isatropolone C Dimer Derivative with Autophagy Activity.

Isatropolone C from Streptomyces sp. CPCC 204095 features a fused cyclopentadienone-tropolone-oxacyclohexadiene tricyclic moiety in its structure. Herein, we report an isatropolone C dimer derivative, di-isatropolone C, formed spontaneously from isatropolone C in methanol. Notably, the structure of di-isatropolone C resolved by NMR reveals a newly formed cyclopentane ring to associate the two isatropolone C monomers. The configurations of four chiral carbons, including a ketal one, in the cyclopentane ring are assigned using quantum NMR calculations and DP4+ probability. The plausible molecular mechanism for di-isatropolone C formation is proposed, in which complex dehydrogenative C-C bond coupling may have happened to connect the two isatropolone C monomers. Like isatropolone C, di-isatropolone C shows the biological activity of inducing autophagy in HepG2 cells.

Unraveling Paradoxical Effects of Large Current Density on Zn Deposition.

Aqueous zinc-based batteries (ZBs) have been widely investigated owing to their intrinsic safety, low cost, and simple assembly. However, the actual behavior of Zn deposition under large current density is still a severe issue associated with obscure mechanism interpretation of ZBs under high loading. Here, differing from the conventional understanding that short circuit is induced by dendrite penetrating under large current density (10-100 mA cm-2), the separator permeation effect is unraveled to illustrate the paradox between smooth deposition and short lifespan. Generally, a dense plating morphology is achieved under large current density because of intensive nuclei and boosted plane growth. Nevertheless, in the scenes applying separators, the multiplied local current density derived from narrow separator channels leads to rapid Zn2+ exhaustion, converting the Zn deposition mode from nucleation control to concentration control, which eventually results in separator permeation and short circuit. This effect is validated in other aqueous metal anodes (Cu, Sn, Fe) and receives similar results. Based on the understanding, a micro-pore (150 µm) sponge foam is proposed as separators for large-current anodes to provide broader Zn2+ path and mitigate the separator permeation effect. This work provides unique perspectives on coordinating fast-charging ability and anode stability of ZBs.

Value of the Air Bronchogram Sign and Other Computed Tomography Findings in the Early Diagnosis of Lung Adenocarcinoma.

OBJECTIVES: The present study aims to explore the application value of the air bronchogram (AB) sign and other computed tomography (CT) signs in the early diagnosis of lung adenocarcinoma (LUAD). METHOD: The pathological information and CT images of 130 patients diagnosed with N0 and M0 solitary pulmonary nodules (diameter ≤3 cm) and treated with surgical resection in our hospital between June 2021 and June 2022 were analyzed. RESULTS: The patients were divided into the benign pulmonary nodule (BPN) group (14 cases), the AIS group (30 cases), the MIA group (10 cases), and the IAC group (76 cases). Among the 116 patients with AIS and LUAD, 96 showed an AB sign. Among the 14 patients with BPN, only 4 patients showed an AB sign. The average CT value and maximum diameter were significantly higher in the IAC group than in the AIS and MIA groups. In the BPN group, 5 patients had an average CT value of >80 HU. Among all LUAD-based groups, there was only 1 patient with a CT value of >60 HU. CONCLUSIONS: The identification of the AB sign based on CT imaging facilitates the differentiation between benign and malignant nodules. The CT value and maximum diameter of pulmonary adenocarcinoma nodules increase with the increase of the malignancy degree. The nodule type, CT value, and maximum diameter are useful for predicting the pathological type and prognosis. If the average CT value of pulmonary nodules is >80 HU, LUAD may be excluded.

Collagen-Based Organohydrogel Strain Sensor with Self-Healing and Adhesive Properties for Detecting Human Motion.

Conductive hydrogels are ideal for flexible sensors, but it is still a challenge to produce such hydrogels with combined toughness, self-adhesion, self-healing, anti-freezing, moisturizing, and biocompatibility properties. Herein, inspired by natural skin, a highly stretchable, strain-sensitive, and multi-environmental stable collagen-based conductive organohydrogel was constructed by using collagen (Col), acrylic acid, dialdehyde carboxymethyl cellulose, 1,3-propylene glycol, and AlCl3. The resulting organohydrogel exhibited excellent tensile (strain >800%), repeatable adhesion (>10 times), self-healing [self-healing efficiency (SHE) ≈ 100%], anti-freezing (-60 °C), moisturizing (>20 d), and biocompatible properties. This organohydrogel also possessed good electrical conductivity (σ = 3.4 S/m) and strain-sensitive properties [GF (gauge factor) = 13.65 with the maximal strain of 400%]. Notably, the organohydrogel had a considerable low-temperature self-healing performance (SHE = 88% at -24 °C) and rapid underwater self-healing property (SHE = 92%, self-healing time <20 min). This type of strain sensor could not only accurately and continuously monitor the large-scale motions of the human body but also provide an accurate response to the human tiny motions. This work not only proposes a development strategy for a multifunctional conductive organohydrogel with multiple environmental stability but also provides potential research value for the construction of biomimetic electronic skin.

BEZ235 reduction of cisplatin resistance on wild-type EGFR non-small cell lung cancer cells.

Cisplatin, as a first-line chemotherapy drug for advanced wild-type epidermal growth factor receptor (wtEGFR) non-small cell lung cancer (NSCLC), often loses effectiveness because of acquired drug resistance. We found that ataxia-telangiectasia mutated (ATM), ataxia-telangiectasia and Rad3-related (ATR) and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) of DNA repair kinases and signal transduction molecules, protein kinase B (AKT)/target mammalian target of rapamycin (mTOR), were significantly phosphorylated in cisplatin-resistant wtEGFR NSCLC cell lines (H358R and A549R) than in their parental cells. Also, BEZ235 (dual phosphatidylinositol-3-kinase (PI3K)/mTOR inhibitor) significantly decreased the phosphorylation levels of these kinases/proteins, as detected by Western blot analysis. In H358R and A549R cells, the results of indirect immunofluorescence, single-cell gel electrophoresis, flow cytometry, methylthiazolyldiphenyl-tetrazolium bromide, clone formation assay, and scratch healing experiment showed that BEZ235 enhanced cisplatin-induced DNA damage and cell apoptosis, and effectively inhibited cellular proliferation/migration when combined with cisplatin. The data indicated that the abnormal activation of ATM/ATR/DNA-PKcs kinases and AKT/mTOR pathway might induce wtEGFR NSCLC cell resistance to cisplatin. The effects of the combination of BEZ235 and cisplatin suggested that BEZ235 should be considered as a combination therapy for patients with cisplatin-resistant wtEGFR NSCLC.

Representing Graphs via Gromov-Wasserstein Factorization.

Graph representation is a challenging and significant problem for many real-world applications. In this work, we propose a novel paradigm called "Gromov-Wasserstein Factorization" (GWF) to learn graph representations in a flexible and interpretable way. Given a set of graphs, whose correspondence between nodes is unknown and whose sizes can be different, our GWF model reconstructs each graph by a weighted combination of some "graph factors" under a pseudo-metric called Gromov-Wasserstein (GW) discrepancy. This model leads to a new nonlinear factorization mechanism of the graphs. The graph factors are shared by all the graphs, which represent the typical patterns of the graphs' structures. The weights associated with each graph indicate the graph factors' contributions to the graph's reconstruction, which lead to a permutation-invariant graph representation. We learn the graph factors of the GWF model and the weights of the graphs jointly by minimizing the overall reconstruction error. When learning the model, we reparametrize the graph factors and the weights to unconstrained model parameters and simplify the backpropagation of gradient with the help of the envelope theorem. For the GW discrepancy (the critical training step), we consider two algorithms to compute it, which correspond to the proximal point algorithm (PPA) and Bregman alternating direction method of multipliers (BADMM), respectively. Furthermore, we propose some extensions of the GWF model, including (i) combining with a graph neural network and learning graph representations in an auto-encoding manner, (ii) representing the graphs with node attributes, and (iii) working as a regularizer for semi-supervised graph classification. Experiments on various datasets demonstrate that our GWF model is comparable to the state-of-the-art methods. The graph representations derived by it perform well in graph clustering and classification tasks.

Exploring and Interacting with the Set of Good Sparse Generalized Additive Models.

In real applications, interaction between machine learning models and domain experts is critical; however, the classical machine learning paradigm that usually produces only a single model does not facilitate such interaction. Approximating and exploring the Rashomon set, i.e., the set of all near-optimal models, addresses this practical challenge by providing the user with a searchable space containing a diverse set of models from which domain experts can choose. We present algorithms to efficiently and accurately approximate the Rashomon set of sparse, generalized additive models with ellipsoids for fixed support sets and use these ellipsoids to approximate Rashomon sets for many different support sets. The approximated Rashomon set serves as a cornerstone to solve practical challenges such as (1) studying the variable importance for the model class; (2) finding models under user-specified constraints (monotonicity, direct editing); and (3) investigating sudden changes in the shape functions. Experiments demonstrate the fidelity of the approximated Rashomon set and its effectiveness in solving practical challenges.

OKRidge: Scalable Optimal k-Sparse Ridge Regression.

We consider an important problem in scientific discovery, namely identifying sparse governing equations for nonlinear dynamical systems. This involves solving sparse ridge regression problems to provable optimality in order to determine which terms drive the underlying dynamics. We propose a fast algorithm, OKRidge, for sparse ridge regression, using a novel lower bound calculation involving, first, a saddle point formulation, and from there, either solving (i) a linear system or (ii) using an ADMM-based approach, where the proximal operators can be efficiently evaluated by solving another linear system and an isotonic regression problem. We also propose a method to warm-start our solver, which leverages a beam search. Experimentally, our methods attain provable optimality with run times that are orders of magnitude faster than those of the existing MIP formulations solved by the commercial solver Gurobi.

Dihydroisatropolone C from Streptomyces and Its Implication in Tropolone-Ring Construction for Isatropolone Biosynthesis.

Isatropolones/isarubrolones are actinomycete secondary metabolites featuring a tropolone-ring in their structures. From the isatropolone/isarubrolone producer Streptomyces sp. CPCC 204095, 7,12-dihydroisatropolone C (H2ITC) is discovered and identified as a mixture of two interchangeable diastereomers differing in the C-6 configuration. As a major metabolite in the mycelial growth period of Streptomyces sp. CPCC 204095, H2ITC can be oxidized spontaneously to isatropolone C (ITC), suggesting H2ITC is the physiological precursor of ITC. Characterization of H2ITC makes us propose dihydrotropolone-ring construction in the biosynthesis of isatropolones.

Fast Sparse Classification for Generalized Linear and Additive Models.

We present fast classification techniques for sparse generalized linear and additive models. These techniques can handle thousands of features and thousands of observations in minutes, even in the presence of many highly correlated features. For fast sparse logistic regression, our computational speed-up over other best-subset search techniques owes to linear and quadratic surrogate cuts for the logistic loss that allow us to efficiently screen features for elimination, as well as use of a priority queue that favors a more uniform exploration of features. As an alternative to the logistic loss, we propose the exponential loss, which permits an analytical solution to the line search at each iteration. Our algorithms are generally 2 to 5 times faster than previous approaches. They produce interpretable models that have accuracy comparable to black box models on challenging datasets.

Highly Sensitive and Robust Polysaccharide-Based Composite Hydrogel Sensor Integrated with Underwater Repeatable Self-Adhesion and Rapid Self-Healing for Human Motion Detection.

Tough, biocompatible, and conductive hydrogel-based strain sensors are attractive in the fields of human motion detection and wearable electronics, whereas it is still a great challenge to simultaneously integrate underwater adhesion and self-healing properties into one hydrogel sensor. Here, a highly stretchable, sensitive, and multifunctional polysaccharide-based dual-network hydrogel sensor was constructed using dialdehyde carboxymethyl cellulose (DCMC), chitosan (CS), poly(acrylic acid) (PAA), and aluminum ions (Al3+). The obtained DCMC/CS/PAA (DCP) composite hydrogels exhibit robust mechanical strength and good adhesive and self-healing properties, due to the reversible dynamic chemical bonds and physical interactions such as Schiff base bonds and metal coordination. The conductivity of hydrogel is 2.6 S/m, and the sensitivity (gauge factor (GF)) is up to 15.56. Notably, the DCP hydrogel shows excellent underwater repeatable adhesion to animal tissues and good self-healing properties in water (self-healing rate > 90%, self-healing time < 10 min). The DCP hydrogel strain sensor can sensitively monitor human motion including finger bending, smiling, and wrist pulse, and it can steadily detect human movement underwater. This work is expected to provide a new strategy for the design of high-performance intelligent sensors, particularly for applications in wet and underwater environments.

Clinicopathological characteristics, survival outcomes and prognostic factors in pleomorphic carcinoma: a SEER population-based study.

BACKGROUND: Pulmonary pleomorphic carcinoma (PPC) is a rare tumor, and it usually has an aggressive clinical course and poor prognosis. We aim to analyze the clinicopathological features, management and prognostic factors of pulmonary pleomorphic carcinoma. PATIENTS AND METHODS: Using the surveillance, epidemiology, and end results (SEER) database, we identified 461 patients of pulmonary pleomorphic carcinoma from 2004 to 2014 including clinicopathological characteristics, treatment modalities and outcome data. RESULTS: The mean age of all PPC patients was 66 years and 58% of the patients were male. Most patients (80%) were white people, 53% were found in the right lung, and lesions were mostly observed in upper lobe (56%). The median overall survival was 9 months and overall 1-, 3- and 5-year survival rate was 45%, 29%, 23%. In Kaplan-Meier analysis, age, marital status, tumor primary site, gender, laterality, SEER summary stage, chemotherapy and surgery were associated with overall survival. Patients received surgery or chemotherapy had a better OS for patients with PPC. Multivariate Cox analysis revealed that SEER summary stage, age, surgery and chemotherapy were found to be independently associated with the OS. Surgery could significantly prolong survival in patients with localized stage and regional stage (HR = 0.120, 95% CI 0.038-0.383, p < 0.001; HR = 0.351, 95% CI 0.212-0.582, p < 0.001) while it did not have great impact on survival in patients with distant stage (p = 0.192). Chemotherapy decreased risk of death by 46% (HR = 0.544, 95% CI 0.393-0.752, p < 0.001) for patients with distant stage, whereas chemotherapy did not confer survival benefits to patients with localized stage and regional stage. But radiation did not have great impact on survival of patients with different stages in this study. CONCLUSIONS: PPC mostly occurred in white people, with a median age of 66 years, and men were more susceptible to this disease. The SEER summary stage, age, surgery and chemotherapy were independently associated with prognosis. Surgery should be considered for the PPC patients with localized stage or regional stage, and chemotherapy should be recommended for the treatment of patients with distant stage.

Cytochrome P450 Monooxygenase for Catalyzing C-42 Hydroxylation of the Glycine-Derived Fragment in Hangtaimycin Biosynthesis.

A hybrid trans-AT PKS/NRPS gene cluster htm was identified with defined boundaries for hangtaimycin biosynthesis in Streptomyces spectabilis CPCC200148. Deoxyhangtaimycin, a new derivative of hangtaimycin, was identified from the htm11 gene knockout mutant. In vitro biochemical assays demonstrated that the cytochrome P450 monooxygenase Htm11 was responsible for the stereoselective hydroxylation of deoxyhangtaimycin to hangtaimycin. More importantly, deoxyhangtaimycin showed activity against influenza A virus at the micromolar level, highlighting its potential as an antiviral lead compound.

Clinical and drug resistance characteristics of Providencia stuartii infections in 76 patients.

OBJECTIVES: To investigate the clinical and drug resistance characteristics of Providencia stuartii infections in the Huainan region of Anhui and provide a reference for the clinical selection of antimicrobial agents. METHODS: This single-center retrospective analysis included 76 patients with P. stuartii infection in Huainan during the period from October 2018 to March 2020. The hospital department in which the patients were treated and the drug susceptibility characteristics of the P. stuartii isolates were recorded. RESULTS: Among the 76 patients, the lung was the most common site of infection, and intensive care unit was the main hospital department. Extended spectrum beta-lactamase screening revealed expression by all 76 isolates of P. stuartii. Of the 76 isolates, 92.1% exhibited multiple drug resistance or extensive drug resistance. P. stuartii isolates were sensitive to cefepime and imipenem, but not to other beta-lactam antibiotics. Twenty isolates were resistant to all 21 types of antibiotics. Of the 20 patients infected with extensively drug-resistant isolates, nine (45%) died. CONCLUSIONS: Drug resistance is increasing in P. stuartii. The antimicrobial agent imipenem may be effective for treatment of P. stuartii infections. Fluoroquinolones, aminoglycosides, and fourth-generation cephalosporins are suitable options for antibiotic therapy.

Gefitinib sensitization of cisplatin-resistant wild-type EGFR non-small cell lung cancer cells.

PURPOSE: The usual first-line strategy of wild-type EGFR (wtEGFR) non-small cell lung cancer (NSCLC) remains cisplatin-based chemotherapy. However, cisplatin often loses effectiveness because most tumors acquire drug resistance over time. As EGFR is the most important pro-survival/proliferation signal receptor in NSCLC cells, we aimed at investigating whether cisplatin resistance is related to EGFR activation and further evaluating the combined effects of cisplatin/gefitinib (EGFR-tyrosine kinase inhibitor, EGFR-TKI) on cisplatin-resistant wtEGFR NSCLC cells. MATERIALS AND METHODS: EGFR activation was analysed in parental and cisplatin-resistant wtEGFR NSCLC cell lines (H358 and H358R, A549 and A549R). Cellular proliferation and apoptosis of H358R/A549R cells treated with cisplatin or gefitinib, alone or in combination were investigated, and the related effector protein was detected by western blot analysis. Anti-tumor effect of two drugs combined was evaluated in animal models of H358R xenografts in vivo. RESULTS: EGFR was significantly phosphorylated in cisplatin-resistant wtEGFR NSCLC cells H358R and A549R than their parental cells. In H358R and A549R cells, anti-proliferative ability of gefitinib was further improved, and gefitinib combined with cisplatin enhanced inhibition of cellular survive/proliferation, and promotion of apoptosis in vitro. The combined effects were also associated with the inhibition of EGFR downstream effector proteins. Similarly, in vivo, gefitinib and cisplatin in combination significantly inhibited tumor growth of H358R xenografts. CONCLUSION: Abnormal activation of EGFR may induce wtEGFR NSCLC cell resistance to cisplatin. The combined effects of cisplatin/gefitinib suggest that gefitinib, as a combination therapy for patients with cisplatin-resistant wtEGFR NSCLC should be considered.

Multiplexed chemiluminescence determination of three acute myocardial infarction biomarkers based on microfluidic paper-based immunodevice dual amplified by multifunctionalized gold nanoparticles.

Acute myocardial infarction (AMI) causes significant mortality and morbidity. The determination of multiple AMI biomarkers is very important for the timely diagnosis of AMI. In this work, simultaneous determination of three AMI biomarkers were achieved by virtue of a three-dimensional (3D) microfluidic paper-analytical device (µPAD) with temporally resolved chemiluminescence (CL) emissions for the first time. A dual-signal amplification strategy was introduced including by employing primary antibody functionalized gold nanoparticles (Ab1-GNPs) immobilized on the detection zone as amplified capture probes, and Co(II) catalyst, secondary antibody, luminol multifunctionalized gold nanoparticles (Co(II)-Ab2-luminol-GNPs) with excellent CL activity as amplified signal probes. CL immunoreactions were performed at three detection zone of the fabricated 3D µPAD by assembling Ab1-GNPs, antigen, and Co(II)-Ab2-luminol-GNPs to form sandwich-type immunocomplexes. Auto separated CL signals with temporal resolution were obtained by time delayed transport of H2O2 to different detection zones for multiplexed analysis. The CL signal obtained by using Co(II)-Ab2-luminol-GNPs as signal probe (10576 a.u.) were about 20-fold higher than that by using conventional horseradish peroxidase labeled antibody modified luminol-GNPs as signal probe (531 a.u.). Finally, three AMI biomarkers including heart-type fatty acid-binding protein (H-FABP), cardiac troponin I (cTnI) and copeptin were quantitatively analyzed in one CL detection run by reading the CL intensity of the obtained three CL emission peaks. The detection range were ultra-wide ranged from 0.1 pg/mL to 1 µg/mL, 0.5 pg/mL to 1 µg/mL and 1 pg/mL to 1 mg/mL with the detection limits down to 0.06 pg/mL, 0.3 pg/mL and 0.4 pg/mL for H-FABP, cTnI and copeptin detection, respectively. The developed µPAD based immunoassay performing multiplexed analysis ability, high sensitivity, ultra-wide dynamic range, favorable selectivity, accessible accuracy and reproducibility, have great application potential for the early diagnosis of AMI.

BEZ235 increases sorafenib inhibition of hepatocellular carcinoma cells by suppressing the PI3K/AKT/mTOR pathway.

BACKGROUND: Sorafenib is an oral multi-kinase inhibitor that inhibits hepatocellular carcinoma (HCC) via the Ras/Raf/MAPK pathway. However, sorafenib loses effectiveness because most tumors acquire drug resistance over time. As the PI3K/AKT/mTOR signaling pathway is also activated abnormally in HCC, we evaluated the effect of sorafenib, in combination with a dual PI3K/mTOR inhibitor, BEZ235, on HCC cell proliferation and survival in vitro. MATERIALS AND METHODS: Biological phenotypes were analysed in HCC cell lines, parental and sorafenib-resistant HepG2 cells (HepG2 and HepG2R), treated with sorafenib or BEZ235, alone or in combination. HCC cellular proliferation and apoptosis were investigated, and perturbations of the Ras/Raf/MAPK and PI3K/AKT/mTOR signaling/survival pathways were evaluated by western blot analysis. RESULTS: BEZ235 enhanced sorafenib inhibition of cellular proliferation, migration, and promotion of apoptosis in HepG2 and HepG2R cells. The combined effects were associated with inhibition of phosphorylation of AKT, mTOR and S6K in the PI3K/AKT/mTOR pathway, whereas the combination of sorafenib and BEZ235 did not significantly alter the Ras/Raf/MAPK pathway compared with the effect of sorafenib alone. CONCLUSION: Sorafenib/BEZ235 combination has potent anti-HCC cell activity. This anti-tumor activity is most likely multi-factorial, mainly involving PI3K down-regulation and AKT, mTOR and S6K dephosphorylation. Combined inhibition of PI3K/AKT/mTOR and Ras/Raf/MAPK pathways enhances sorafenib inhibition of HCC. The results of these in vitro studies suggest that trials of combined sorafenib and BEZ235 in the treatment of HCC should be considered.

Three-dimensional microfluidic paper-based device for multiplexed colorimetric detection of six metal ions combined with use of a smartphone.

A simple double-layered three-dimensional (3D) microfluidic paper-based analytical device (µPAD) was designed for the simultaneous determination of six metal ions-Fe(III), Ni(II), Cr(VI), Cu(II), Al(III), and Zn(II)-for the first time. The 3D µPAD was composed of two paper layers: a top pretreatment layer and a bottom colorimetric detection layer. The sample solution added to the central sample reservoir of the 3D µPAD could be automatically divided into eight flow pathways and be automatically pretreated while flowing through the pretreatment zones located in the microfluidic channels, and automatically carried out the chromogenic reactions after reaching the detection zones. Random diffusion of the chromogenic reagents was effectively prevented by transport of the pretreated sample solution to the detection zones through 3D microfluidic channels with an L-type circuitous flow route design, resulting in highly increased color uniformity and reproducibility. Combined with use of a flat LED lamp as an upward lighting source and a smartphone as a convenient detector, improved color perception, highly enhanced sensitivity, and an extended detection range were obtained. Finally, the double-layered 3D µPAD was applied to the multiplexed determination of the six metal ions in mixtures and environmental samples with satisfactory results. Detection limits as low as 0.2, 0.3, 0.1, 0.03, 0.08, and 0.04 mg/L for Fe(III), Ni(II), Cr(VI), Cu(II), Al(III), and Zn(II) detection, respectively, were achieved, which are about one order of magnitude lower than obtained with previously reported µPADs for the detection of metal ions. The present 3D µPAD is simple, fast, selective, sensitive, and user-friendly, and holds great application potential for multiplexed on-site analysis.

High-resolution temporally resolved chemiluminescence based on double-layered 3D microfluidic paper-based device for multiplexed analysis.

In this work, a double-layered three-dimensional (3D) microfluidic paper-based analytical device (µPAD) with high resolution temporally resolved chemiluminescence (CL) emissions were designed for multiplexed CL analysis. The temporally resolved CL emissions were obtained by virtue of the 3D branched microfluidic channel design, which create time delays for luminol transported from one detection zone to another. The peak intensity and peak shape of the temporally resolved CL emissions were quite stable and base-line separated with resolution as high as 21.2-24.4. Then, the fabricated µPAD was applied to multiplexed determination of glucose, lactate, cholesterol, and choline as model analytes. The sample was added to four detection zone modified with CL catalyst cobalt ion and different oxidase by virtue of chitosan. When luminol flowed to µPAD, four temporally resolved CL peaks were successively generated from the cobalt ion catalyzed CL reactions between luminol and generated H2O2 from the specific enzymatic reactions between the oxidase and the analytes. The generated four CL emission peaks in the CL kinetic curve increased in proportion to the concentrations of glucose, lactate, cholesterol, and choline, respectively. Finally, four linear calibration curves were obtained for the detection of glucose (0.01-1.0 mmol/L), lactate (0.02-5.0 mmol/L), cholesterol (0.01-0.4 mmol/L), and choline (0.001-1.0 mmol/L). The detection limits were as low as 8 µmol/L, 15 µmol/L, 6 µmol/L, and 0.07 µmol/L for glucose, lactate, choline, and cholesterol detection, respectively. The present work provides a new strategy for the fabrication of simple and sensitive 3D µPAD with high resolution temporally resolved CL emissions for multiplexed CL analysis, which holds great application potential for point-of-care diagnosis.

An ultrasensitive label-free colorimetric assay for glutathione based on Ag+ regulated autocatalytic oxidation of o-phenylenediamine.

The discriminative determination of glutathione (GSH) over cysteine (Cys) and homocysteine (Hcy) is still challenging in bioassays due to their similar functional groups. Herein, a novel, simple, rapid, sensitive and cost-effective label-free colorimetric method for the selective determination of GSH over Cys and Hcy was proposed. In this assay, firstly, o-phenylenediamine (OPD) could be oxidized by silver ions (Ag+) to produce silver nanoparticles (AgNPs) and pale yellow colored 2,3-diaminophenazine (shorted as OPDox) with absorbance peak center at 429 nm. The as-formed AgNPs could further catalyze the redox reaction between OPD and Ag+. In the presence of GSH, GSH could chelate with Ag+, inhibiting the oxidation ability of Ag+, and link with AgNPs, influence the catalytic ability of AgNPs. Furthermore, GSH possesses strong reducibility to reduce OPDox, resulting in color fading of the detection solution and decrease in absorbance intensity. The proposed Ag+-OPD based sensing system exhibited a wide linear range from 2 nM to 1 µM for GSH detection, with the limit of detection as low as 1.7 nM. Moreover, this developed method was successfully applied to GSH detection in plasma and urine samples with satisfied results.