A coalitional game-based joint monitoring mechanism for combating COVID-19.

In the absence of effective treatment for COVID-19, disease prevention and control have become a top priority across the world. However, the general lack of effective cooperation between communities makes it difficult to suppress the community spread of the global pandemic; hence repeated outbreaks of COVID-19 have become the norm. To address this problem, this paper considers community cooperation in disease monitoring and designs a joint epidemic monitoring mechanism, in which adjacent communities cooperate to enhance their monitoring capability. In this work, we formulate the epidemiological monitoring process as a coalitional game. Then, we propose a Shapley value-based payoffs distribution scheme for the coalitional game. A comprehensive analytical framework is developed to evaluate the advantages and sustainability of the cooperation between communities. Experimental results show that the proposed mechanism performs much better than the conventional non-cooperative monitoring design and can greatly increase each community's payoffs.

A ratiometric fluorescent probe with large Stokes shift and emission shift for sensing hydrazine in living organisms.

As a highly toxic reagent, hydrazine (N2H4) is notorious to human beings and the environment. To simply and conveniently detect N2H4 in environmental and biological systems, a ratiometric fluorescent probe MA-N2H4 was developed with excellent sensitivity and selectivity. Probe MA-N2H4 was readily prepared based on a naphthalene as the fluorescent scaffold and an indanedione group as the responsive moiety for N2H4. This probe displayed a red-emitting fluorescence at 670 nm with a large Stokes shift (200 nm). After treatment with N2H4, a significant blue-shifted emission at 440 nm could be observerd, which led to an extremely large emission wavelength shift (230 nm). The fluorescent intensity ratio (I440/I670) of probe MA-N2H4 was rapidly and significantly increased (273-fold) within 18 min. The detection limit for N2H4 was 0.5 µM. In addition, the probe was successfully employed for tracking N2H4 in living cells and zebrafish through a ratiometric manner.

Prediction of asymptomatic COVID-19 infections based on complex network.

Novel coronavirus pneumonia (COVID-19) epidemic outbreak at the end of 2019 and threaten global public health, social stability, and economic development, which is characterized by highly contagious and asymptomatic infections. At present, governments around the world are taking decisive action to limit the human and economic impact of COVID-19, but very few interventions have been made to target the transmission of asymptomatic infected individuals. Thus, it is a quite crucial and complex problem to make accurate forecasts of epidemic trends, which many types of research dedicated to deal with it. In this article, we set up a novel COVID-19 transmission model by introducing traditional SEIR (susceptible-exposed-infected-removed) disease transmission models into complex network and propose an effective prediction algorithm based on the traditional machine learning algorithm TrustRank, which can predict asymptomatic infected individuals in a population contact network. Our simulation results show that our method largely outperforms the graph neural network algorithm for new coronary pneumonia prediction and our method is also robust and gives good results even if the network information is incomplete.

Rational Development of Dual-Ratiometric Fluorescent Probes for Distinguishing between H2S and SO2 in Living Organisms.

For better investigating the complicated relationships between H2S and SO2, simultaneously detecting and visualizing them with good selectivity is crucial. However, most sensing mechanisms for H2S and SO2 probes are based on the addition reactions with the double bonds, which have no selectivity. In this work, by introducing an active triple bond into 4-dicyanovinyl-7-diethylamino-coumarin, we construct two unique sensors for not only distinguishing between H2S and SO2 but also sensing H2S and SO2 in a dual-ratiometric manner. Moreover, the modified sensor was successfully applied in living cells and zebrafish for discriminating H2S and SO2.

A Ratiometric, Fast-Responsive, and Single-Wavelength Excited Fluorescent Probe for the Discrimination of Cys and Hcy.

The ratiometric detection of cysteine (Cys) and homocysteine (Hcy) is very challenging because of their highly similar chemical structures and properties. By introducing the phenylethynyl group into a coumarin dye as the sensing group, the ratiometric fluorescent probe CP was developed to selectively and rapidly discriminate between Cys and Hcy. With a single-wavelength excitation, the presence of Cys or Hcy induced the probe to produce distinct ratiometric fluorescence changes: from red (λmaxem = 608 nm) to blue (λmaxem = 485 nm) toward Cys and from red to mixed red/blue toward Hcy. Moreover, the probe was capable of visualizing and discriminating between intracellular Cys and Hcy in HeLa cells and zebrafish by exhibiting different ratiometric fluorescence signals.

A near-infrared fluorescent probe for hydrogen polysulfides detection with a large Stokes shift.

Due to the crucial biological roles of hydrogen polysulfides (H2Sn) in living systems, the selective determination of H2Sn is essential. In this work, we reported a turn-on fluorescent probe, JSI-Sn, for H2Sn with high sensitivity and good selectivity. Probe JSI-Sn displayed a near-infrared emission (λmaxEm = 701 nm) and a large Stokes shift (123 nm) in the presence of H2Sn in solution. Using probe JSI-Sn as an indispensable tool, the monitoring of intracellular H2Sn in living cells and zebrafish were realized.

Rational Design of a Two-Photon Ratiometric Fluorescent Probe for Hypochlorous Acid with a Large Stokes Shift.

By introducing the tetrahydroquinoxaline group as the electron donor to enhance intramolecular charge transfer effect, we deliberately designed a coumarin derivative, TQC-HClO, to serve as a two-photon ratiometric fluorescent probe for imaging hypochlorous acid in cells and zebra fish with good sensitivity and high selectivity. TQC-HClO displayed an obvious two-photon absorbance cross-section (over 100 GM in 800-840 nm), large Stokes shifts (159 to 173 nm), and a ratiometric fluorescence change from orange (λmaxem = 583 nm) to red (λmaxem = 650 nm) in response to hypochlorous acid.

Investigation of the Relationship Between H2O2 and HClO in Living Cells by a Bifunctional, Dual-ratiometric Responsive Fluorescent Probe.

As two important reactive oxygen species, hydrogen peroxide (H2O2) and hypochlorous acid (HClO) play vital roles in many physiological and pathological processes. However, the relationship between these two species is seldom investigated, in part, because of the lack of robust molecular tools that can simultaneously visualize HClO and H2O2 in biosystems. In this work, we present a design strategy to construct a single fluorescent probe that can detect H2O2 and HClO by simultaneously monitoring two distinct detection channels. In the design, one phenothiazine-based coumarin serves as a chromophore and sensor for HClO, while a second coumarin precursor containing a boronate ester acts as a sensor for H2O2. After a head-to-head screening of three candidates differing in their coumarin precursor moieties, probe CSU1 was found to have the optimal characteristics. As shown experimentally, it is able to detect them selectively and sensitively to generate distinct fluorescence signals and patterns in living cells. Furthermore, the endogenous generation of HClO from H2O2 and Cl- catalyzed by myeloperoxidase enzyme in living cells can be clearly monitored by the probe. These studies demonstrate the potential of the probe as a powerful tool to investigate the interplay of HClO and H2O2 in oxidative stress.

A dual-ratiometric fluorescent probe for individual and continuous detection of H2S and HClO in living cells.

HClO and H2S are crucial for maintaining the homeostasis in cells and play vital roles in many physiological and pathological processes. Herein, we present a fluorescent probe that can respectively and simultaneously detect H2S and HClO in a dual-ratiometric manner with good linearity. Utilizing this probe, the imaging of intracellular H2S or/and HClO in living cells in a ratiometric manner was achieved.

Red-emitting fluorescent probe for discrimination of Cys/Hcy and GSH with a large Stokes shift under a single-wavelength excitation.

In this work, we based on an iminocoumarin borate complex to design and synthesize a red-emitting fluorescent probe, THQ-BF2-O-NBD, to discriminatively detect Cys/Hcy and GSH with a large Stokes shift (100 nm). This probe responded to GSH to display red fluorescence with λmax = 630 nm. In contrast, two well-separated emission bands with λmax = 565 and 630 nm were observed in the solution of THQ-BF2-O-NBD with Cys/Hcy. The probe was capable to distinguish Cys/Hcy from GSH in real biological systems.