As a primary cause of food contamination and human diseases,
Salmonella
Typhimurium can easily form a biofilm that is difficult to remove from food surfaces, and often causes significant invisible ...threats to food safety. Although berberine has been widely used as an anti-infective drug in traditional medicine, some basic principles underlying its mechanism, especially the interaction between berberine and type I fimbriae genes, has not been verified yet. In this study, two strains of major fimbrial gene mutants (Δ
fimA
and Δ
fimH
) were constructed to demonstrate the possible action of berberine on type I fimbriae genes. The broth microdilution method was used to determine the antibacterial activity of berberine against selected strains (WT, Δ
fimA
, and Δ
fimH
). Cell agglutination experiments revealed that the number of
S
. Typhimurium type I fimbriae reduced after berberine treatment, which was consistent with transmission electron microscopy results. Quantitative real-time PCR experiments also confirmed that berberine reduced
fimA
gene expression, indicating a certain interaction between berberine and
fimA
gene. Furthermore, confocal laser scanning microscopy imaging of biofilm clearly revealed that berberine prevents biofilm formation by reducing the number of type I fimbriae. Overall, it is well speculated for us that berberine could be an excellent combating-biofilm drug in clinical microbiology and food preservation.
Key points
• Reduce the number of fimbriae.
• Berberine targeting fimA.
• Effective biofilm inhibitor.
In recent years, strain sensors have penetrated various fields. The capability of sensors to convert physical signals into electrical signals is of great importance in healthcare. However, it is ...still challenging to obtain sensors with high sensitivity, large operating range and low cost. In this paper, a stretchable strain sensor made of a double-layer conductive network, including a biomimetic multilayer graphene-Ecoflex (MLG-Ecoflex) substrate and a multilayer graphene-carbon nanotube (MLG-CNT) composite up-layer was developed. The combined action of the two layers led to an excellent performance with an operating range of up to 580% as well as a high sensitivity (gauge factor (GF
) of 1517.94). In addition, a pressure sensor was further designed using the bionic vein-like structure with a multi-layer stacking of MLG-Ecoflex/MLG-CNT/MLG-Ecoflex to obtain a relatively high deformation along the direction of thickness. The device presented a high sensing performance (up to a sensitivity of 0.344 kPa
) capable of monitoring small movements of the human body such as vocalizations and gestures. The good performance of the sensors together with a simple fabrication procedure (flip-molding) make it of potential use for some applications, for example human health monitoring and other areas of human interaction.
Strain sensors that can rapidly and efficiently detect strain distribution and magnitude are crucial for structural health monitoring and human–computer interactions. However, traditional electrical ...and optical strain sensors make access to structural health information challenging because data conversion is required, and they have intricate, delicate designs. Drawing inspiration from the moisture-responsive coloration of beetle wing sheaths, we propose using Ecoflex as a flexible substrate. This substrate is coated with a Fabry–Perot (F–P) optical structure, comprising a “reflective layer/stretchable interference cavity/reflective layer”, creating a dynamic color-changing visual strain sensor. Upon the application of external stress, the flexible interference chamber of the sensor stretches and contracts, prompting a blue-shift in the structural reflection curve and displaying varying colors that correlate with the applied strain. The innovative flexible sensor can be attached to complex-shaped components, enabling the visual detection of structural integrity. This biomimetic visual strain sensor holds significant promise for real-time structural health monitoring applications.
The food-borne pathogen
Salmonella enterica
serovar Typhimurium (
S.
Typhimurium) causes self-limiting gastroenteritis in humans and is not easily eradicated because it often attaches to suitable ...surfaces to form biofilms that have high resistance to disinfectants and antimicrobials. To develop an alternative strategy for the treatment of biofilms, it is necessary to further explore the effects of flagellar motility on the development process of
Salmonella
biofilms. Here, we constructed flagella mutants (Δ
flgE
and Δ
fliC
) to systematically study this process. By comparing them with wild-type strains, we found that these mutants lacking flagellar motility form fewer biofilms in the early stage, and the formed mature biofilms contain more cells and extracellular polymeric substances (EPS). In addition, fewer mutant cells adhered to glass plates compared with wild-type cells even after 6 h of incubation, suggesting that flagellar motility plays a significant role in preliminary cell-surface interactions. More importantly, the motility of wild-type strain was greatly decreased when they were treated with carbonyl cyanide m-chlorophenylhydrazone, which inhibited flagellar motility and reduced biofilm formation, as in the case of the Δ
flgE
mutant. Overall, these findings suggest that flagellar motility plays an important role in
Salmonella
biofilm initiation and maturation, which can help us to counteract the mechanisms involved in biofilm formation and to develop more rational control strategies.
A sensitive and selective method for the determination of the antibiotic chloramphenicol (CAP) is described, which is based on double signal amplification and GO as an efficient fluorescence ...quencher. The nucleic acid probe is composed of three well-defined regions, viz. the signal probe I, the signal probe II, and the capture probe. The capture probe will bind to CAP specifically and the signal probes produce a significant fluorescence signal. One end of the signal probes is labeled with the fluorophore 6-carboxyfluorescein (FAM). The labeled probes can be adsorbed on graphene oxide (GO) via π-stacking interactions, upon which the green fluorescence of FAM (measured at excitation/emission wavelengths of 490/514 nm) is quenched. On addition of CAP, the aptamer/CAP complexes are formed, and this leads to the restoration of fluorescence due to the removal of the probes from GO. The double signal probes, together with GO as quencher, improve the fluorescence signal significantly and lower the detection limit. Under optimized conditions, the assay works in the 20- to 200-ppb CAP concentration range and has a 0.3-ppb detection limit. It is also successfully applied to the determination of CAP in spiked swine urine samples. The recoveries from spiked swine urine samples are between 97.73 and 108.56%, and the repeatability (expressed as the RSD) is between 4.66 and 8.90%.
Graphical abstract
The constructed DNA probes form a stable structure and bind to chloramphenicol specifically. One end of signal probes was labeled with the fluorophore 6-carboxyfluorescein (FAM). The detection sensitivity of chloramphenicol was significantly enhanced by using double signal amplification, which was superior to the traditional methods. The quantities of CAP can be achieved by fluorescence increment.
A colorimetric method was developed using G-quadruplex and gold nanoparticles (AuNPs) for determination of
Escherichia coli K88
(
ETEC K88
). It was composed of two modules: (1) an aptamer as ...biorecognizing element and (2) a capturing DNA (modified with AuNPs at 5′) as a transducer. In the absence of target bacteria, the aptamer can form stable double strands with capturing DNA, preventing the binding of capturing DNA to the G-quadruplex. However, the double strands of capturing DNA and aptamer are untied due to the stronger binding of aptamers to bacteria in the presence of target bacteria. As a result, the G-quadruplex binds to capture DNA and leads to the aggregation and color change of AuNPs, which can be monitored by a spectrophotometer or visualization. The quantitative determination was achieved by monitoring the optical density change of AuNPs solution at 524 nm after target addition. Under optimal conditions, the method has a low detection limit (1.35 × 10
2
CFU mL
−1
) and a linear response in the range 10
2
to 10
6
CFU mL
−1
.
Graphical abstract
The manuscripts describe a colorimetric method for the detection of
ETEC K88
by using intermolecular G-quadruplex to induce the agglomeration of gold nanoparticles, which can be directly used to determine the presence of bacteria with our naked eyes.
Resistin-like molecules (RELMs) are highly cysteine-rich proteins, including RELMα, RELMβ, Resistin, and RELMγ. However, RELMs exhibit significant differences in structure, distribution, and ...function. The expression of RELMs is regulated by various signaling molecules, such as IL-4, IL-13, and their receptors. In addition, RELMs can mediate numerous signaling pathways, including HMGB1/RAGE, IL-4/IL-4Rα, PI3K/Akt/mTOR signaling pathways, and so on. RELMs proteins are involved in wide range of physiological and pathological processes, including inflammatory response, cell proliferation, glucose metabolism, barrier defense, etc., and participate in the progression of numerous diseases such as lung diseases, intestinal diseases, cardiovascular diseases, and cancers. Meanwhile, RELMs can serve as biomarkers, risk predictors, and therapeutic targets for these diseases. An in-depth understanding of the role of RELMs may provide novel targets or strategies for the treatment and prevention of related diseases. Video abstract.
Combined therapeutic strategies for bacterial infection have attracted worldwide attention owing to their faster and more effective therapy with fewer side effects compared with monotherapy. In this ...work, gold-platinum nanodots (AuPtNDs) are simply and quickly synthesized by a one-step method. They not only exhibit powerful peroxidase-like activity but also confer a higher affinity for hydrogen peroxide (H
O
), which is 3.4 times that of horseradish peroxidase. Under 808 nm laser irradiation, AuPtNDs also have excellent photothermal conversion efficiency (50.53%) and strong photothermal stability. Excitingly, they can combat bacterial infection through the combination of chemodynamic and photothermal therapy.
antibacterial results show that the combined antibacterial strategy has a broad-spectrum antibacterial property against both
(Gram negative, 97.1%) and
(Gram positive, 99.3%). Animal experiments further show that nanodots can effectively promote the healing of bacterial infection wounds. In addition, owing to good biocompatibility and low toxicity, they are hardly traceable in the main organs of mice, which indicates that they can be well excreted through metabolism. These results reveal the application potential of AuPtNDs as a simple and magic multifunctional nanoparticle in antibacterial therapy and open up new applications for clinical anti-infective therapy in the near future.
In seismic exploration, field data inevitably involves with noises and missing traces along the spatial coordinates, which affects seismic inversion and imaging. Seismic data interpolation is modeled ...by solving an inverse problem with regularization terms in mathematics. However, sparse or low-rank priors in model-based methods cannot capture complex information from seismic data. A denoiser learned by a convolution neural network (CNN) can be regarded as an implicit prior that helps improve the accuracy of the model. For this motivation, we choose an unbiased DnCNN as a blind denoiser and use a stochastic gradient algorithm to iteratively train the interpolated model, thus using the a priori information implied in the denoiser to interpolate the seismic data. We demonstrate the feasibility of the proposed method through synthetic and field data with comparative experiments, where it has excellent performance with handling interpolation and spatial aliasing.
Displacement damage to the structure and properties of phase-change materials caused by high-energy particle radiation is a major challenge to the development of optical storage systems for space ...applications. In this article, a 10 MeV proton irradiation was carried out on an amorphous and crystalline phase-change material of Ge2Sb2Te5 (namely, a-GeSbTe and c-GeSbTe), respectively, and radiation-induced local structural and optical property changes were then studied using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) as well as a spectrophotometer. The results indicated that proton bombardment caused the partial breaking of the Sb-Te and Ge-Te bonds in both the a-GeSbTe and c-GeSbTe samples, but with a greater number of broken bonds in c-GeSbTe which led to an obvious drop in optical reflectivity together with an enhanced surface roughness as compared to a-GeSbTe. Stopping and range of ions in matter (SRIM) simulations further verified that c-GeSbTe experienced a higher degree of displacement damage, with peak damage values up to <inline-formula> <tex-math notation="LaTeX">3.3\times 10^{-5} </tex-math></inline-formula> dpa. Meanwhile, vacancies in a-GeSbTe tended to gather toward the film bottom, while those in c-GeSbTe were commonly clustered near the film middle. This article provides crucial insights into understanding the response of Ge2Sb2Te5 to proton irradiation.
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