Dual Switchable CRET-Induced Luminescence of CdSe/ZnS Quantum Dots (QDs) by the Hemin/G-Quadruplex-Bridged Aggregation and Deaggregation of Two-Sized QDs

The hemin/G-quadruplex-catalyzed generation of chemiluminescence through the oxidation of luminol by H₂O₂ stimulates the chemiluminescence resonance energy transfer (CRET) to CdSe/ZnS quantum dots (QDs), resulting in the luminescence of the QDs. By the cyclic K⁺-ion-induced formation of the hemin/G-quadruplex linked to the QDs, and the separation of the G-quadruplex in the presence of 18-crown-6-ether, the ON-OFF switchable CRET-induced luminescence of the QDs is demonstrated. QDs were modified with nucleic acids consisting of the G-quadruplex subunits sequences and of programmed domains that can be cross-linked through hybridization, using an auxiliary scaffold. In the presence of K⁺-ions, the QDs aggregate through the cooperative stabilization of K⁺-ion-stabilized G-quadruplex bridges and duplex domains between the auxiliary scaffold and the nucleic acids associated with the QDs. In the presence of 18-crown-6-ether, the K⁺-ions are eliminated from the G-quadruplex units, leading to the separation of the aggregated QDs. By the cyclic treatment of the QDs with K⁺-ions/18-crown-6-ether, the reversible aggregation/deaggregation of the QDs is demonstrated. The incorporation of hemin into the K⁺-ion-stabilized G-quadruplex leads to the ON-OFF switchable CRET-stimulated luminescence of the QDs. By the mixing of appropriately modified two-sized QDs, emitting at 540 and 610 nm, the dual ON-OFF activation of the luminescence of the QDs is demonstrated

Structural Transformation of Guanine Coordination Motifs in Water Induced by Metal Ions and Temperature

The transformation effects of metal ions and temperature on the DNA base guanine (G) metal–organic coordination motifs in water have been investigated by scanning tunneling microcopy (STM). The G molecules form an ordered hydrogen-bonded structure at the water–highly oriented pyrolytic graphite interface. The STM observations reveal that the canonical G/9H form can be transformed into the G/(3H,7H) tautomer by increasing the temperature of the G solution to 38.6 °C. Moreover, metal ions bind with G molecules to form G₄Fe₁³⁺, G₃Fe₃²⁺, and the heterochiral intermixed G₄Na₁⁺ metal–organic networks after the introduction of alkali-metal ions in cellular environment

Switching Photonic and Electrochemical Functions of a DNAzyme by DNA Machines

DNA nanostructures acting as DNA machines are described. Specifically, DNA “walkers” assembled on nucleic acid scaffolds and triggered by fuel/antifuel strands are activated in solution or on surfaces, for example, electrodes or semiconductor CdSe/ZnS quantum dots (QDs). The DNA machines led to the switchable formation or dissociation of the hemin/G-quadruplex DNAzyme on the DNA scaffolds. This enabled the chemiluminescence, chemiluminescence resonance energy transfer (CRET), electrochemical, or photoelectrochemical transduction of the switchable states of the different DNA machines

Utility of T-Cell Interferon-γ Release Assays for Etiological Diagnosis of Classic Fever of Unknown Origin in a High Tuberculosis Endemic Area — a pilot prospective cohort

<div><p>Background</p><p>Tuberculosis (TB), especially extrapulmonary TB is still the leading cause of fever of unknown origin (FUO) in China. However, diagnosis of TB still remains a challenge. The aim of this study was to evaluate the diagnostic value of T-SPOT.<i>TB</i> for etiological diagnosis of classic FUO in adult patients in a high TB endemic area.</p><p>Methods</p><p>We prospectively enrolled patients presenting with classic FUO in a tertiary referral hospital in Beijing, China, to investigate the diagnostic sensitivity, specificity, predictive values and likelihood ratio of T-SPOT.<i>TB</i>. Clinical assessment and T-SPOT.<i>TB</i> were performed. Test results were compared with the final confirmed clinical diagnosis.</p><p>Results</p><p>387 hospitalized patients (male n = 194, female n = 193; median age 46 (range 29–59) yrs) with classic FUO were prospectively enrolled into this study. These FUOs were caused by infection (n = 158, 40.8%), connective tissue disease (n = 82, 21.2%), malignancy (n = 41, 10.6%) and miscellaneous other causes (n = 31, 8.0%), and no cause was determined in 75 (19.4%) patients. 68 cases were diagnosed as active TB eventually. The sensitivity of T-SPOT.<i>TB</i> for the diagnosis of active TB was 70.6% (95%CI 58.9–80.1%), while specificity was 84.4% (95%CI 79.4–88.4%), positive predictive value was 55.8% (95%CI 45.3–65.8%), negative predictive value was 91.2% (95%CI 86.7–94.2%). Among these 68 active TB patients, 12 cases were culture or histology confirmed (11 cases with positive T-SPOT.<i>TB</i>, sensitivity was 91.7%) and 56 cases were clinically diagnosed (37 cases with positive T-SPOT.<i>TB</i>, sensitivity was 66.1%); 14 cases were pulmonary TB (13 cases with positive T-SPOT.<i>TB</i>, sensitivity was 92.9%) and 54 cases were extrapulmonary TB (35 cases with positive T-SPOT.<i>TB</i>, sensitivity was 64.8%).</p><p>Conclusions</p><p>For patients presenting with classic FUO in this TB endemic setting, T-SPOT.<i>TB</i> appears valuable for excluding active TB, with a high negative predictive value.</p></div

Diagnostic Value of Interferon-γ Release Assays on Pericardial Effusion for Diagnosis of Tuberculous Pericarditis

<div><p>Diagnosis of tuberculous pericarditis remains a challenge. We aimed in this study to evaluate the diagnostic value of T-SPOT.<i>TB</i> on pericardial effusion for diagnosis of tuberculous pericarditis. Patients with suspected tuberculous pericarditis were enrolled consecutively between August 2011 and December 2015. T-SPOT.<i>TB</i> was performed on both pericardial effusion mononuclear cells (PEMCs)and peripheral blood mononuclear cells (PBMCs). Sensitivity, specificity, predictive value (PV), and likelihood ratio (LR) of T-SPOT.<i>TB</i> on PEMCs and PBMCs were analyzed. Among the 75 patients enrolled, 24 patients (32%) were diagnosed with tuberculous pericarditis, 38 patients (51%) with nontuberculous pericarditis, and 13 patients (17%) were clinically indeterminate and were excluded from the final analysis. The sensitivity, specificity, positive PV (PPV), negative PV (NPV), positive LR (LR+), and negative LR (LR-) of T-SPOT.<i>TB</i> on PEMCs was 92%,92%,88%,95%,11.61, and 0.09, respectively, compared to 83%, 95%, 91%, 90%,15.83, and 0.18, respectively of T-SPOT.<i>TB</i> on PBMCs. In patients with tuberculous pericarditis, the median frequencies of spot-forming cells (SFCs) of T-SPOT.<i>TB</i> on PEMCs and PBMCs was 172SFCs/10⁶MCs (IQR 39~486), and 66 SFCs/10⁶MCs (IQR 24~526), respectively, but the difference was not statistically significant (P = 0.183). T-SPOT.<i>TB</i> on PEMCs appeared to be a valuable and rapid diagnostic method for diagnosis of tuberculous pericarditis with high sensitivity and specificity.</p></div

Diagnostic category of tuberculous pericarditis.

<p>Diagnostic category of tuberculous pericarditis.</p

Frequencies of T-SPOT.TB on PEMCs and PBMCs in patients with tuberculous pericarditis.

<p>Frequencies of T-SPOT.TB on PEMCs and PBMCs in patients with tuberculous pericarditis.</p

Sensitivity, specificity, PPV, NPV, LR+, LR-, and area under the receiver operating characteristic curve (AUC) of T-SPOT.TB on PEMCs and PBMCs of patients with tuberculous pericarditis.

<p>Sensitivity, specificity, PPV, NPV, LR+, LR-, and area under the receiver operating characteristic curve (AUC) of T-SPOT.TB on PEMCs and PBMCs of patients with tuberculous pericarditis.</p

Density Functional Theory Study on the Enhancement Mechanism of the Photocatalytic Properties of the g‑C₃N₄/BiOBr(001) Heterostructure

The van der Waals heterostructures fabricated in two semiconductors are currently attracting considerable attention in various research fields. Our study uses density functional theory calculations within the Heyd–Scuseria–Ernzerhof hybrid functional to analyze the geometric structure and electronic structure of the g-C3N4/BiOBr(001) heterojunction in order to gain a better understanding of its photocatalytic properties. The calculated band alignments show that g-C3N4/BiOBr can function as a type-II heterojunction. In this heterojunction, the electrons and holes can effectively be separated at the interface. Moreover, we find that the electronic structure and band alignment of g-C3N4/BiOBr(001) can be tuned using external electric fields. It is also noteworthy that the optical absorption peak in the visible region is enhanced under the action of the electric field. The electric field may even improve the optical properties of the g-C3N4/BiOBr(001) heterostructure. Given the results of our calculations, it seems that g-C3N4/BiOBr(001) may be significantly superior to visible light photocatalysis

Flowchart of enrolling patients.

<p>Flowchart of enrolling patients.</p