Comparing the antibacterial activity of chitin nanocrystals with chitin: exploring the feasibility of chitin nanocrystals as novel pesticide nanocarriers in agriculture

BACKGROUND

In recent years, nanomaterials-based pesticide carriers have garnered significant attention and sparked extensive research. However, most studies have primarily focused on investigating the impact of physical properties of nanomaterials, such as size and modifiable sites, on drug delivery efficiency of nano-pesticides. The limited exploration of biologically active nanomaterials poses a significant obstacle to the advancement and widespread adoption of nano-pesticides. In this study, we prepared chitin nanocrystals (ChNC) based on acid hydrolysis and systematically investigated the differences between nano- and normal chitin against plant bacteria (Pseudomonas syringae pv. tabaci). The primary objective was to seek out nanocarriers with heightened biological activity for the synthesis of nano-pesticides.

RESULTS

Zeta potential analysis, Fourier Transform infrared spectrometry (FTIR), X-Ray diffraction (XRD), Atomic force microscopy (AFM) and Transmission electron microscopy (TEM) identified the successful synthesis of ChNC. ChNC showcased remarkable bactericidal activity at comparable concentrations, surpassing that of chitin, particularly in its ability to inhibit bacterial biofilm formation. Furthermore, ChNC displayed heightened effectiveness in disrupting bacterial cell membranes, resulting in the leakage of bacterial cell contents, structural DNA damage, and impairment of DNA replication. Lastly, potting experiments revealed that ChNC is notably more effective in inhibiting the spread and propagation of bacteria on plant leaves.

CONCLUSION

ChNC exhibited higher antibacterial activity compared to chitin, enabling efficient control of plant bacterial diseases through enhanced interaction with bacteria. These findings offer compelling evidence of ChNC's superior bacterial inhibition capabilities, underscoring its potential as a promising nanocarrier for nano-pesticide research. © 2023 Society of Chemical Industry.

Effects of Serotonin on Cell Viability, Permeability of Bovine Mammary Gland Epithelial Cells and Their Transcriptome Analysis

Serotonin (5-HT) has been reported to play an important role in mammary gland involution that is defined as the process through which the gland returns to a nonlactating state. However, the overall picture of the regulatory mechanisms of 5-HT and the effects of serotonylation on mammary gland involution still need to be further investigated. The current study aimed to investigate the effects of 5-HT on global gene expression profiles of bovine mammary epithelial cells (MAC-T) and to preliminarily examine whether the serotonylation involved in the mammary gland involution by using Monodansylcadaverine (MDC), a competitive inhibitor of transglutaminase 2. Results showed that a high concentration of 5-HT decreased viability and transepithelial electrical resistance (TEER) in MAC-T cells. Transcriptome analysis indicated that 2477 genes were differentially expressed in MAC-T cells treated with 200 μg/mL of 5-HT compared with the control group, and the Notch, p53, and PI3K-Akt signaling pathways were enriched. MDC influenced 5-HT-induced MAC-T cell death, fatty acid synthesis, and the formation and disruption of tight junctions. Overall, a high concentration of 5-HT is able to accelerate mammary gland involution, which may be regulated through the Notch, p53, and PI3K-Akt signaling pathways. Serotonylation is involved in bovine mammary gland involution.

Intraguild Prey Served as Alternative Prey for Intraguild Predators in a Reciprocal Predator Guild between Neoseiulus barkeri and Scolothrips takahashii

The predatory mites Neoseiulus barkeri (Hughes) and the predatory thrips Scolothrips takahashii (Priesner) are known as potential biocontrol agents for the two-spotted spider mite Tetranychus urticae (Koch). These two predator species occur simultaneously on crops in agricultural ecosystems and are proved to be involved in life-stage specific intraguild predation. The intraguild prey may play a role in securing the persistence of the intraguild predators during food shortage periods. To understand the potential of intraguild prey as food source for intraguild predators in the N. barkeri and S. takahashii guild at low T. urticae densities, the survival, development and reproduction of both predators was determined when fed on heterospecific predators. The choice tests were conducted to determine the preference of the intraguild predator between the intraguild prey and the shared prey. Results showed that 53.3% N. barkeri and 60% S. takahashii juveniles successfully developed when fed on heterospecific predators. Female intraguild predators of both species fed on intraguild prey survived and laid eggs throughout the experiment. In the choice test, both intraguild predator species preferred their extraguild prey T. urticae. This study suggested that intraguild prey served as an alternative prey for intraguild predators prolonged survival and ensured the reproduction of intraguild predators during food shortage, ultimately decreasing the need for the continual release of the predators.

A turn-on fluorescent nanoprobe based on N-doped silicon quantum dots for rapid determination of glyphosate

N-Doped silicon quantum dots (N-SiQD) were synthesized using N-[3-(trimethoxysily)propyl]-ethylenediamine and citric acid as silicon source and reduction agent, respectively. The N-SiQD shows a strong blue fluorescence with a high quantum yield of about 53%. It is found that a selective static quenching process occurs between N-SiQDs and Cu2+. Glyphosate can inhibit this phenomenon and trigger the rapid fluorescence enhancement of the quenched N-SiQDs/Cu2+ system due to the specific interaction between Cu2+ and glyphosate. With such a design, a turn-on fluorescent nanoprobe based on N-SiQD/Cu2+ system was established for rapid determination of glyphosate. The determination signal of N-SiQD/Cu2+ was measured at the optimum emission wavelength of 460 nm after excitation at 360 nm. Under optimal conditions, the turn-on nanoprobe showed a linear relationship between fluorescent response and glyphosate concentrations in the range 0.1 to 1 μg mL-1. The limit of determination was calculated to 7.8 ng mL-1 (3σ/S). Satisfactory recoveries were obtained in the determination of spiked water samples, indicating the potential use for environmental monitoring. Graphical abstract Schematic representation of N-SiQD/Cu2+ system for glyphosate determination. Fluorescence quenching of N-SiQDs induced by copper ions and the succedent fluorescent "turn on" triggered by glyphosate.