An aptamer-based electrochemical biosensor was successfully developed and applied in the rapid detection of pathogenic Escherichia coli (E. coli) in licorice extract. The thiolated capture probes were firstly immobilized on a gold electrode, and then the biotinylated aptamer probes for E. coli were introduced by hybridization with the capture probes. Due to the stronger interaction between the aptamer and the E. coli, a part of the biotinylated aptamers will dissociate from the capture probes in the presence of E. coli. The residual biotinylated aptamer probes can quantitatively bind with streptavidin-alkaline phosphatase. Subsequently, α-naphthyl phosphate substrate was catalytically hydrolyzed to generate electrochemical response, which could be recorded by a differential pulse voltammetry. The dependence of the peak current on the logarithm of E. coli concentration in the range from 5.0 × 10² colony forming units (CFU)/mL to 5.0 × 10⁷ CFU/mL exhibited a linear trend with a detection limit of 80 CFU/mL. The relative standard deviation of 5 successive scans was 5.3%, 4.5% and 1.1% for 5.0 × 10², 5.0 × 10⁵ and 5.0 × 10⁷ CFU/mL E. coli, respectively. In the detection of the licorice extract samples, the results obtained from the proposed strategy and traditional culture counting method were close to each other, but the time consumption was only ~1/30 compared with the traditional method. These results demonstrate that the designed biosensor can be potentially utilized for rapid microbial examination in traditional Chinese medicine and relevant fields.

In chronic infections caused by Staphylococcus aureus, biofilm is a major virulence factor. In Staphylococcus aureus biofilms, bacteria are embedded in a matrix of extracellular polymeric substances and are highly tolerant to antimicrobial drugs. However, the lack of effective solutions to inhibit biofilm formation remains a challenge, and the mechanism of inhibition of biofilm formation targeting extracellular polymeric substances is unclear. The aim of the present study was to investigate the inhibitory mechanisms of Plumbagin against Staphylococcus aureus biofilms formation by affecting secretion of extracellular polymeric substances using the high-content screening. Our results showed Plumbagin (16 µg/mL) inhibited biofilm formation, revealing a significant reduction in both biomass and bacterial metabolic activity, and disrupted the biofilm structure, leading to a significant decrease in both biological volume and average thickness (P ≤ 0.01). High-content screening imaging indicated that the Plumbagin treatment induced alterations in the extracellular polymeric substances of Staphylococcus aureus biofilm, significantly reducing the quantities of extracellular polysaccharide, proteins and extracellular DNA. Interestingly, extracellular DNA within the matrix was found to be the most sensitive to Plumbagin treatment. Extracellular DNA formation was significantly inhibited at a concentration of 4 µg/mL, whereas the inhibition of extracellular polysaccharide and proteins required a higher concentration of 8 µg/mL. Overall, these results demonstrated the inhibitory effects of Plumbagin on Staphylococcus aureus biofilm formation and extracellular polymeric substances secretion, suggesting that extracellular DNA may be a potential target for the anti-biofilm activity of Plumbagin. These findings will provide new insights into the mode of action of Plumbagin in treating infections caused by Staphylococcus aureus biofilms.

The pericarps of Zanthoxylum bungeanum (ZBP) and leaves of Zanthoxylum bungeanum (ZBL) are popular spices in China, and they have pharmacological activities as well. In this experiment, the volatile organic compounds (VOCs) of the pericarps of Zanthoxylum bungeanum in Sichuan (SJ) and its leaves (SJY) and the pericarps of Zanthoxylum bungeanum in Shaanxi (SHJ) and its leaves (SHJY) were analyzed by headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and headspace solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). The fingerprint of HS-GC-IMS and the heat maps of HS-SPME-GC-MS were established. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were performed. The results showed that a total of 95 components were identified, 62 components identified by HS-SPME-GC-MS and 40 components identified by HS-GC-IMS, of which 7 were the same. The analysis found that SJ and SHJ were obviously distinguished, while SJY and SHJY were not. There were considerably fewer VOCs in the leaves than in the pericarps. In the characterization of the VOCs of ZBL and ZBP, the flavor of ZBP was more acrid and stronger, while the flavor of ZBL was lighter and slightly acrid. Thirteen and eleven differential markers were identified by HS-GC-IMS and HS-SPME-GC-MS, respectively. This is helpful in distinguishing between SHJ and SJ, which contributes to their quality evaluation.

This work was designed to investigate the dynamic changes process of non-volatile organic compounds (n-VOCs) and volatile organic compounds (VOCs) in mulberries during different growth periods using UPLC-Q-Orbitrap-MS, HS-SPME-GC-MS, and HS-GC-IMS. A total of 166 compounds were identified, including 68 n-VOCs and 98 VOCs. Furthermore, principal component analysis (PCA), random forest analysis (RFA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were used to analyze differences in mulberries at different ripening stages. A total of 74 compounds appeared or disappeared at different ripening periods and 24 compounds were presented throughout the growth process. Quantitative analysis and antioxidant experiments revealed that as the mulberries continued to mature, flavonoids and phenolic acids continued to increase, and the best antioxidant activity occurred from stage IV. Conclusively, an effective strategy was established for analyzing the composition change process during different growth periods, which could assist in achieving dynamic change process analysis and quality control.

Quality evaluation of phytomedicines is limited to small molecules as quality markers, even for herbs with high sugar contents. We established a high-resolution method for distinguishing similar medicinal materials using sugar as quality marker, taking Schisandrae Chinensis Fructus (SCF) and Schisandrae Sphenantherae Fructus (SSF) as an example. High performance liquid chromatography with an evaporative light-scattering detector (HPLC-ELSD), high performance size exclusion chromatography coupled with multi-angle laser light scattering detector and refractive index detector (HPSEC-MALLS-RID) and high performance liquid chromatography with photo-diode array (HPLC-PDA) after 1-phenyl-3-methyl-5-pyrazolone (PMP) pre-column derivatization were used respectively to determine monosaccharide contents, molecular weights and monosaccharide compositions of polysaccharides in this study. The differences of SCF and SSF from ten producing areas were compared by principal component analysis (PCA) and hierarchical cluster analysis (HCA). Results showed that contents of fructose and glucose were similar between SCF and SSF. Molecular weight (Mw) of SCF polysaccharides was ranging from 1.561 × 10² to 6.599 × 10² kDa, and that of SSF polysaccharides was ranging from 8.524 × 10² to 1.7416 × 10³ kDa. Schisandra polysaccharides were mainly composed of mannose, galacturonic acid, glucose, galactose and arabinose. Based on PCA and HCA, SCF and SSF from ten different areas were classified into three categories. With great accuracy, sensitivity and stability, the methods established in this study had important reference value for quality evaluation, development and utilization of saccharide components in medicinal materials.