Simultaneous quantitative analysis of Escherichia coli, Staphylococcus aureus and Salmonella typhimurium using surface-enhanced Raman spectroscopy coupled with partial least squares regression and artificial neural networks.

Simultaneous detection of mixed bacteria accurately and sensitively is a major challenge in microbial quality control field. In this study, we proposed a label-free SERS technique coupled with partial least squares regression (PLSR) and artificial neural networks (ANNs) for quantitative analysis of Escherichia coli, Staphylococcus aureus and Salmonella typhimurium simultaneously. SERS-active and reproducible Raman spectra can be acquired directly upon the bacteria and Au@Ag@SiO2 nanoparticle composites on the surface of gold foil substrates. After applying different preprocessing models, SERS-PLSR and SERS-ANNs quantitative analysis models were developed to map SERS spectra of concentrations of the Escherichia coli, Staphylococcus aureus and Salmonella typhimurium, respectively. Both models achieved high prediction accuracy and low prediction error, while the performance of SERS-ANNs model in both quality of fit (R2 > 0.95) and accuracy of predictions (RMSE < 0.06) was superior to SERS-PLSR model. Therefore, it is feasible to develop simultaneous quantitative analysis of mixed pathogenic bacteria by proposed SERS methodology.

A universal approach for sensitive and rapid detection of different pathogenic bacteria based on aptasensor-assisted SERS technique.

An assembled-aptasensor based on Fe3O4@Au@Ag nanocomposites grafting onto the gold foil was prepared, which can be developed into a universal approach for sensitive and rapid detection of various pathogenic bacteria, such as Escherichia coli (E. coli), Salmonella typhimurium (S. typhimurium), Staphylococcus aureus (S. aureus), Listeria monocytogenes (L. monocytogenes), Pseudomonas aeruginosa (P. aeruginosa), and Shigella flexneri (S. flexneri). Firstly, the gold foil paper was modified with thiolated capture probe and SERS tag in proportion, and at the same time, the specific thiolated aptamer probe for corresponding pathogenic bacteria was fixed with Fe3O4@Au@Ag nanocomposites. An obvious Raman signal can be subsequently increased about 106 times by the external electromagnetic field enhancement at the "hot spots" caused by the hybridization of aptamer and capture probe. But in the presence of target pathogenic bacteria, Raman intensity will decrease as Fe3O4@Au@Ag nanocomposites are dissociated from gold foil. Thus, all of the concentrations of the six kinds of pathogenic bacteria both in PBS and liquorice extract showed an obvious negative linear correlation with the Raman intensity of SERS tag in the range of 10-107 CFU/mL with detection limits were all lower than 10 CFU/mL. And there was no significant difference between our method and the plate counting method. Besides, the assembled-aptasensor had superior specific recognition ability even in the mixed interfering bacteria. Our study showed that this assembled-aptasensor had good specific detection ability to a variety of foodborne pathogens based on magnetic field-assisted SERS technique, which can be used for rapid and sensitive detection of a variety of pathogens in complex substrates.

Switchable Synthesis of 2-Methylene-3-aminoindolines and 2-Methyl-3-aminoindoles Using Calcium Carbide as a Solid Alkyne Source.

The one-pot three-component method for the switchable synthesis of 2-methylene-3-aminoindolines and 2-methyl-3-aminoindoles by reactions of N-(2-formylaryl)sulfonamides, secondary amines, and calcium carbide is described. This protocol has the salient features of the use of an inexpensive, abundant, and easy-to-handle solid alkyne source, avoiding the use of flammable and explosive gaseous acetylene as an original alkyne source. In addition, a wide scope of substrates, satisfactory yield, and simple workup procedure are also advantages of this method.

Three-Component One-Pot Construction of 2-Aryl-4H-benzo[4,5]thiazolo[3,2-a]pyrimidines Using Solid Calcium Carbide as a Surrogate of Gaseous Acetylene.

A concise method for the construction of 2-aryl-4H-benzo[4,5]thiazolo[3,2-a]pyrimidines using solid calcium carbide instead of gaseous acetylene as an alkyne source and 2-aminobenzothiazoles and aromatic aldehydes as substrates through one-pot three-component cascade reactions is described. The salient features for this protocol are the use of an inexpensive and easy-to-handle alkyne source, noble-metal-free condition, wide substrate scope and functional tolerance, satisfactory yield, and simple workup procedure.

lncRNA DANCR Promotes Proliferation and Metastasis of Breast Cancer Cells Through Sponging miR-4319 and Upregulating VAPB.

Background: Breast cancer is one of the most prevalent cancers that often occur in females. Long noncoding RNA differentiation antagonizing nonprotein coding RNA (DANCR) has been involved in the pathogenesis of various tumors, including breast cancer. This study aimed to investigate the role and underlying mechanism of DANCR in breast cancer. Materials and Methods: The level of DANCR was detected in breast cancer tissues and cells by quantitative real-time polymerase chain reaction (qRT-PCR). Cell viability was evaluated by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay. Cell apoptosis was assessed using flow cytometry. Cell migration and invasion were estimated by the Transwell assay. The relationship between DANCR, miR-4319, and vesicle-associated membrane protein-associated protein B (VAPB) was confirmed by bioinformatic analysis and dual-luciferase reporter assay. The level of microRNA-4319 (miR-4319) was tested by qRT-PCR. The expression of VAPB was measured by qRT-PCR or Western blot assay. Results: DANCR and VAPB were upregulated, while miR-4319 was downregulated in breast cancer tissues and cells. Knockdown of DANCR hindered proliferation, migration, and invasion and promoted apoptosis of breast cancer cells. DANCR knockdown inhibited breast cancer development through regulating miR-4319. Inhibition of miR-4319 restrained breast cancer cell progression by targeting VAPB. Moreover, DANCR regulated VAPB expression by sponging miR-4319 in breast cancer cells. Conclusion: DANCR facilitated breast cancer cell progression through regulating the miR-4319/VAPB axis, indicating that DANCR might be a potential biomarker and therapeutic target for breast cancer treatment.

A disposable gold foil paper-based aptasensor for detection of enteropathogenic Escherichia coli with SERS analysis and magnetic separation technology.

Rapid and sensitive detection of enteropathogenic Escherichia coli (EPEC) in fluids with complex background is an important task for safety quality control in the field of medicine, environment, and food. In this study, a gold foil paper-based aptasensor was developed for the detection of enteropathogenic EPEC O26:K60 with surface-enhanced Raman spectroscopy (SERS) and magnetic separation technology mediated by Fe3O4@Au composite. The gold foil paper was firstly modified with thiolated capture probe and SERS tag. The thiolated aptamer probe for EPEC was immobilized onto a Fe3O4@Au composite. In the presence of EPEC, highly specific recognition between the aptamer probe and EPEC made the Fe3O4@Au composite partially dissociated from the gold foil paper. This led to a decreased Raman intensity response, which showed an obvious negative linear correlation with increasing concentration of EPEC over a wide concentration range from 10 to 107 CFU/mL under an excitation wavelength of 633 nm. The detection limit was about 2.86 CFU/mL in a buffer solution and a licorice extractum and the detection time was only 2.5 h. The results demonstrate that the gold foil paper-based aptasensor can be an excellent biosensing platform that offers a reliable, rapid, and sensitive alternative for EPEC detection.

[Application of oscillating chemical fingerprint technology combined with mathematical analysis method in quality control analysis of traditional Chinese medicine and food].

Oscillating chemical fingerprint is a nonlinear dynamic fingerprint technology that reflects the overall redox activity of the entire system based on potential-time changes in multi-stage chemical reactions. This article summarizes the application of oscillating chemical fingerprint technology combined with mathematical analysis method in the qualitative and quantitative analysis of traditional Chinese medicine and food in recent years, including similarity analysis, principal component analysis, cluster analysis and other qua-litative analysis methods, as well as linear, logarithmic, exponential, polynomial, multivariate analysis and other quantitative analysis methods, so as to provide meaningful information for further quality control analysis of the oscillation chemical fingerprint technology in the field of traditional Chinese medicine and food.

[Qualitative and quantitative analysis of Rhodobryum giganteum by using nonlinear oscillating chemical fingerprint technique].

A new method for qualitative and quantitative analysis of Rhodobryum giganteum by using the nonlinear oscillating chemical was established for improving the quality control standard of R. giganteum. Its potential(E)/time(t) curve was recorded by electrochemical workstation in the oscillation reaction system of BrO~-_3-Ce(SO_4)_2-H_2SO_4-malonic acid/tartaric acid. The nonlinear oscillating chemical fingerprints were investigated for repeatability, and it was found that the RSD values of the four characteristic parameters of R. giganteum were less than 4.1%, indicating a good repeatability and high precision of this experiment. After optimizing the experimental parameters such as particle size, rotation speed and temperature, a new method based on nonlinear oscillating chemical was used for qualitative and quantitative analysis of R. giganteum. The results showed that there was a good linear relationship between the induction time/the period of oscillation and the dosage of herbs(0.1-1.1 g), with the relative coefficients of 0.978 and 0.975, respectively. Besides, the highest potential showed a nonlinear relationship with the dosage of herbs, with the relative coefficient of 0.999. This method was also used to discriminate the R. giganteum and R. roseum. They were similar in appearance, but their fingerprints were quite different. Independent sample t test results showed that there were significant differences in the oscillation time, the maximum amplitude and the induction time, providing a basis for the identification of the basic sources of Herba Rhodobryi Rasei.