Application of histochemical stains for rapid qualitative analysis of the lignin content in multiple wood species

Rapid qualitative analysis was used to determine the influence of the lignin content of wood cell walls on the compression and bending properties of multiple wood species. The lignin type and cell wall content of Cunninghamia lanceolate, Fagus longipetiolata, Betula alnoides, Fraxinus mandshurica, and Tectona grandis was analyzed via histochemical staining, which included: the Mäule staining reaction, the Weisner staining reaction, and a fluorescence reaction. The results showed that the more red the Mäule staining reaction was, the greater the Syringyl lignin (S-type lignin) content was, and the more yellowish-brown the Mäule staining reaction was, the greater the Guaiacyl lignin (G-type lignin) content was. In addition, the more reddish-purple the Wiesner staining reaction was, the greater the lignin content was. The greater the brightness value of the fluorescence reaction was, the greater the lignin content was. Due to the negative correlation between the lignin content of the wood cell wall and the bending and compression properties of the wood, the application of histochemical stains for the analysis of wood lignin content could provide a reference and experimental basis for bending and compression treatments of various woods.

Detection of Histamine Based on Gold Nanoparticles with Dual Sensor System of Colorimetric and Fluorescence

Gold nanoparticles (Au-NPs), with the dual sensor system of colorimetric and fluorescence responses, were developed for the determination of histamine as a spoilage monitor for distinguishing lifetime and freshness of aquatic products. Upon addition of histamine, the absorption coefficient orders of magnitude via the interaction of free electrons and photons were affected, and the characteristic absorption peak of Au-NPs was red-shifted from 520 nm to 664 nm. Meanwhile, the large amino groups in the networks of histamine-Au-NPs with high molecular orbital exhibited excellent fluorescence behavior at 415 nm. Au-NPs offered a range of 0.001–10.0 μM and 0.01–1.0 μM with a limit of detection of 0.87 nM and 2.04 nM by UV-vis and fluorescence spectrum assay, respectively. Moreover, Au-NPs could be used to semiquantitatively analyze histamine with the naked eye, since the significant colorimetric and fluorescence reaction of Au-NPs solution that coincided with different concentrations of histamine can be observed as the histamine concentration was 0.1–1.0 μM. Both of the dual-sensor systems of Au-NPs were successfully applied to the quantitative analysis of histamine in fresh salmon muscle, suggesting the simplicity and rapidity in the dual detection approaches of Au-NPs might be suitable for spoilage assay of aquatic food to ensure food safety.

Detection and Imaging Application of miRNA in Cells and Living Organisms with Nano-Fluorescent Probes Made by Novel Synthesis Materials

As a kind of rare earth fluorescent material, the rare earth upconversion nanomaterial can be applied in various fields such as biological detection and imaging, solar cells, and safe positioning, which has attracted wide concerns. In this study, the novel material is applied to the preparation of biological nano-fluorescent probes. Due to its broad UV absorption spectrum, cobalt oxyhydroxide is selected and used as a quencher for upconversion nanomaterials. Once the cobalt oxyhydroxide is placed on upconversion nanomaterials, the surface reaction can effectively remove the fluorescence reaction of the upconversion nanomaterial. In terms of the molecular miRNA tests for cells and living organisms, the nano-fluorescent probe can reduce the fluorescence intensity of miRNA, while the control group can finish the normal fluorescence reaction. The designed fluorescent probe can adjust the contents of cobalt oxyhydroxides and cells to regulate the fluorescence intensity. In terms of the miRNA sensitivity tests, the fluorescence intensity detected by the nano-fluorescent probe is significantly lower than that in the control group, which can be observed through the fluorescence recovery tests of the chemical system. After the addition of miRNA obtained from cells or living organisms, the fluorescent probe has apparently changed the fluorescence intensity of miRNA in cells/living organisms. Also, the detection range of miRNA is effectively expanded, i.e., the different concentrations of miRNA can be detected by adjusting the ratio of the components of the fluorescent probes, which indicates the excellent sensitivity of the fluorescent probe in detecting miRNA in cells and living organisms. In terms of the miRNA tests for cells, different degrees of cancer cells are selected. The fluorescent probe can discriminate the concentration of cancer cells according to fluorescence imaging of cancer cells, thereby further explaining that the fluorescent probe has high-sensitivity in bio-detection.