A fluorescence aptamer sensor utilizing WS2 nanosheets for sensitive detection of patulin: enhanced specificity and wide applicability.

A tungsten disulfide (WS2) nanosheet-based aptamer sensor was developed to detect patulin (PAT). The 5'-end of the PAT aptamer was modified with a cyanine 3 (Cy3) fluorophore, which self-assembled on WS2 nanosheets. The interaction between the Cy3 fluorophore at the 5'-end of the PAT aptamer and the WS2 nanosheets resulted in reduced fluorescence (FL) intensity due to fluorescence resonance energy transfer (FRET). The introduction of PAT into this sensing system led to hybridization with the PAT aptamer, forming a G-quadruplex/PAT complex with low affinity for the WS2 nanosheet surface. This hybridization increased the distance between the Cy3 fluorophore and the WS2 nanosheets, inhibiting FRET and producing a strong FL signal. Under optimal experimental conditions, the FL intensity of the sensing system demonstrated an excellent linear correlation with PAT concentrations ranging from 0.5 to 40.0 ng mL-1, and it achieved a detection limit (S/N = 3) of 0.23 ng mL-1. This sensing system offers enhanced specificity for PAT detection and has the potential for broad application in detecting other toxins by substituting the sequence of the recognition aptamer.

Rupture process of the 2021 M7.4 Maduo earthquake and implication for deformation mode of the Songpan-Ganzi terrane in Tibetan Plateau.

The deformation mode of the Tibetan Plateau is of crucial importance for understanding its construction and extrusion processes, as well as for the assessment of regional earthquake potential. Block motion and viscous flow models have been proposed to describe the deformation field but are not fully supported by modern geophysical observations. The 2021 Mw 7.4 Maduo earthquake, which occurred inside the Songpan-Ganzi terrane (SGT) in central-east Tibet, provides a chance to evaluate the associated deformation mode of the region. We conduct a joint inversion for this earthquake and resolve a bilateral rupture process, which is characterized by super- and subshear rupture velocities, respectively. We interpret this distinct rupture behavior to be the result of the respective slip concentration depths of the two ruptured segments. We analyze geological, seismic, and geodetic evidence and find that the SGT upper crust shows distributed shear deformation and distinct transverse anisotropy, which are associated with folded structures originating from compression of the paleo-Tethys ocean accretional prism realigned by following shear deformation. The SGT receives lateral shear loading from its NS boundary and accommodates a right-step sinistral motion across the terrane boundary faults. The unique tectonic setting of the SGT defines locations and behaviors of internal faulting and strong earthquakes such as the 2021 Maduo earthquake, with the latter occurring on slow-moving faults at intervals of several thousands of years.

A hemostatic keratin/alginate hydrogel scaffold with methylene blue mediated antimicrobial photodynamic therapy.

Uncontrollable bleeding and infection are two of the most common causes of trauma-related death. Yet, developing safe materials with high hemostatic and antibacterial effectiveness remains a challenge. Keratin-based biomaterials have been reported to exhibit the functions of enhancing platelet binding and activating and facilitating fibrinogen polymerization. In this study, we designed a hemostatic material with good biodegradability, biocompatibility, hemostatic ability, and antibacterial function to solve the shortcomings of common hemostatic materials. Methylene blue-loaded keratin/alginate composite scaffolds were prepared by the freeze-gelation method. The composite scaffolds exhibited over 1600% liquid absorption, well-interconnected pores, good biocompatibility, and biodegradability. We find that the keratin/alginate composite scaffolds' synergistic action may significantly reduce hemostasis time. To prevent infection, the drug-loaded scaffolds generated high burst release by absorbing wound exudate in the early stages of wound healing. The results obtained by the antimicrobial photoinactivation assay in vitro suggest that an antimicrobial photodynamic effect might be triggered, thereby preventing the fast growth of colonies.

Keratin-Based Nanoparticles with Tumor-Targeting and Cascade Catalytic Capabilities for the Combinational Oxidation Phototherapy of Breast Cancer.

Photodynamic therapy (PDT) holds tantalizing prospects of a prominent cancer treatment strategy. However, its efficacy remains limited by virtue of the hypoxic tumor microenvironment and the inadequate tumor-targeted delivery of photosensitizers, and these can be further exacerbated by the lack of development of a well-controlled nitric oxide (NO) release system at the target site. Inspired by Chinese medicine, we propose a revealing new keratin application. Keratin has garnered attention as an NO generator; however, its oncological use has rarely been investigated. We hypothesized that the incorporation of a phenylboronic acid (PBA) targeting ligand/methylene blue (MB) photosensitizer with a keratin NO donor would facilitate precise tumor delivery, enhancing PDT. Herein, we demonstrated that MB@keratin/PBA/d-α-tocopherol polyethylene glycol 1000 succinate (TPGS) nanoparticles (MB@KPTNPs) specifically targeted breast cancer cells and effectively suppressed their growth. Through MB-mediated biometabolism, the endocytic MB@KPTNPs produced a sufficient amount of intracellular NO that reduced the glutathione level while boosting the efficiency of PDT. A therapeutic combination of NO/PDT was therefore achieved, resulting in significant inhibition of both in vivo tumor growth and lung metastasis. These findings underscore the importance of utilizing keratin-based nanoparticles that simultaneously combine targeting of the tumor and self-generating NO with a cascading catalytic ability as a novel oxidation therapeutic strategy for enhancing PDT.

Fast and high-efficiency synthesis of 2-substituted benzothiazoles via combining enzyme catalysis and photoredox catalysis in one-pot.

An efficient and green method, combining enzymatic and visible-light catalysis for synthesis of the widely applicable 2-substituted benzothiazoles, has been developed. This method features a relay catalysis protocol consisting of biocatalytic promiscuity and visible-light-induced subsequent oxidization of 2-phenyl benzothiazolines. The whole reaction process is very high-efficiency, achieving 99% yield in just 10 min, under an air atmosphere, nearly 100% atomic utilization, and the 2-substituted benzothiazole products were obtained in good to excellent yields with a wide range of substrates. This reaction is the other example of combining the non-natural catalytic activity of hydrolases with visible-light catalysis for organic synthesis and the catalytic system does not require additional oxidants or metals, which is good for the environment.

Combining photo-redox and enzyme catalysis for the synthesis of 4H-pyrimido[2,1-b] benzothiazole derivatives in one pot.

A novel strategy combining visible-light and enzyme catalysis in one pot for the synthesis of 4H-pyrimido[2,1-b] benzothiazole derivatives from alcohols is described for the first time. Fourteen 4H-pyrimido[2,1-b] benzothiazole derivatives were prepared with yields of up to 98% under mild reaction conditions by a simple operation. The photoorgano catalyst rose Bengal (rB) was employed to oxyfunctionalise alcohols to aldehydes. Compared with aldehydes, alcohols with more stable properties and lower cost, thus we used photocatalysis to oxidize alcohols into aldehydes. Next, the enzyme was used to further catalyze the reaction of Biginelli to produce the target product of 4H-pyrimidine [2,1-b] benzothiazole. Experimental results show that this method provides a more efficient and eco-friendly strategy for the synthesis of 4H-pyrimido[2,1-b] benzothiazole derivatives.

Observer-Based Event-Triggered Predictive Control for Networked Control Systems under DoS Attacks.

This paper studies the problem of DoS attack defense based on static observer-based event-triggered predictive control in networked control systems (NCSs). First, under the conditions of limited network bandwidth resources and the incomplete observability of the state of the system, we introduce the event-triggered function to provide a discrete event-triggered transmission scheme for the observer. Then, we analyze denial-of-service (DoS) attacks that occur on the network transmission channel. Using the above-mentioned event-triggered scheme, a novel class of predictive control algorithms is designed on the control node to proactively save network bandwidth and compensate for DoS attacks, which ensures the stability of NCSs. Meanwhile, a closed-loop system with an observer-based event-triggered predictive control scheme for analysis is created. Through linear matrix inequality (LMI) and the Lyapunov function method, the design of the controller, observer and event-triggered matrices is established, and the stability of the scheme is analyzed. The results show that the proposed solution can effectively compensate DoS attacks and save network bandwidth resources by combining event-triggered mechanisms. Finally, a smart grid simulation example is employed to verify the feasibility and effectiveness of the scheme's defense against DoS attacks.

Aggregation-Induced Emission Probes for Specific Turn-On Quantification of Bovine Serum Albumin.

A series of aggregation-induced emission (AIE) fluorescence probes, coined 4H-pyrimido[2,1-b]benzothiazole derivatives, has been synthesized by Biginelli reactions. Utilizing spectroscopic techniques, their photophysical properties have been comprehensively investigated in working environment both in vitro and in vivo. Density functional theory (DFT) calculations were performed to better understand the mechanism of these probes. The interactions between 4H-pyrimido[2,1-b]benzothiazoles with different substituents and bovine serum albumin (BSA) were analyzed using UV-vis and fluorescence spectroscopy, synchronous fluorescence, and docking analysis. Studies found that 4H-pyrimido[2,1-b]benzothiazole could bind to bovine serum albumin (BSA) through a hydrogen bond and hydrophobic interactions, resulting in enhancement of fluorescence emission of probes 1a-6f and fluorescence quenching of BSA. Combined with cell imaging experiments, these provide information on potential effects of benzothiazoles on disease treatment.