Optimized Synthesis of Layered Double Hydroxide Lactate Nanosheets and Their Biological Effects on Arabidopsis Seedlings

Background: Layered double hydroxide lactate nanosheets (LDH-lactate-NS) are powerful carriers for delivering macro-molecules into intact plant cells. In the past few years, some studies have been carried out on DNA/RNA transformation and plant disease resistance, but little attention has been paid to these factors during LDH-lactate-NS synthesis and delamination, nor has their relationship to the DNA adsorption capacity or transformation efficiency of plant cells been considered. Results: Since the temperature during delamination alters particle sizes and zeta potentials of LDH-lactate-NS products, we compared the LDH-lactate-NS stability, DNA adsorption rate and delivery efficiency of fluorescein isothiocyanate isomer I (FITC) of them, found that the LDH-lactate-NS obtained at 25℃ has the best characters for delivering biomolecules into plant cell. To understand the potential side effects and cytotoxicity of LDH-lactate-NS to plants, we compared the root growth rate between the Arabidopsis thaliana seedlings grown in the culture medium with 1-300 μg/mL LDH-lactate-NS and equivalent raw material, Mg(lactate)2 and Al (lactate)3. Phenotypic analysis showed LDH in a range of 1-300 μg/mL can enhance the root elongation, whereas the same concentration of raw materials dramatically inhibited root elongation, suggesting the nanocrystallization has a dramatical de-toxic effect to Mg(lactate)2 and Al (lactate)3. Since enhancing of root elongation by LDH is an unexpected phenomenon, we further designed experiments to investigate influence of LDH to Arabidopsis seedlings. We further used the gravitropic bending test, qRT-PCR analysis of auxin transport proteins, non-invasive micro-test technology and liquid chromatography-mass spectrometry to investigate the auxin transport and distribution in Arabidopsis root. Results indicated that LDH-lactate-NS affect root growth by increasing the polar auxin transport.Conclusions: Optimal synthesized LDH-lactate-NS can delivery biomolecules into intact plant cells with high efficiency and low cytotoxity. The working solution of LDH-lactate-NS can promote root elongation via increase the polar auxin transport in Arabidopsis roots.

Gold nanocluster mediated delivery of siRNA to intact plant cells for efficient gene knockdown

RNA interference (RNAi), which involves the delivery of small interfering RNA molecules (siRNA), has been used to validate target genes in plants, to understand and control cellular metabolic pathways, and as a ‘green’ alternative for crop pest tolerance. Conventional siRNA delivery methods such as viruses and Agrobacterium-mediated delivery exhibit limitations in host plant species range and their use can result in uncontrolled DNA integration into the plant host genome. Here, we synthesize polyethyleneimine functionalized gold nanoclusters (PEI-AuNCs) to mediate siRNA delivery into intact plant cells and show these constructs enable efficient gene knockdown. We demonstrate that functionalized AuNCs protect siRNA from RNase degradation and are small enough (~2 nm) to bypass the plant cell wall which exhibits a size exclusion limit of 5-20 nm. These AuNCs in turn enable up to 76.5 ± 5.9% GFP mRNA knockdown efficiency with no cellular toxicity. Our data suggest this simple and biocompatible platform for passive delivery of siRNA into intact plant cells could have broad applications in plant biotechnology.

Establishment of a Cell Suspension Culture of Eysenhardtia platycarpa: Phytochemical Screening of Extracts and Evaluation of Antifungal Activity

Eysenhardtia platycarpa (Fabaceae) is a medicinal plant used in Mexico. Biotechnological studies of its use are lacking. The objective of this work was to establish a cell suspension culture (CSC) of E. platycarpa, determine the phytochemical constituents by spectrophotometric and gas chromatography‒mass spectrometry (GC‒MS) methods, evaluate its antifungal activity, and compare them with the intact plant. Friable callus and CSC were established with 2 mg/L 1-naphthaleneacetic acid plus 0.1 mg/L kinetin. The highest total phenolics of CSC was 15.6 mg gallic acid equivalents (GAE)/g dry weight and the total flavonoids content ranged from 56.2 to 104.1 µg quercetin equivalents (QE)/g dry weight. The GC‒MS analysis showed that the dichloromethane extracts of CSC, sapwood, and heartwood have a high amount of hexadecanoic acid (22.3–35.3%) and steroids (13.5–14.7%). Heartwood and sapwood defatted hexane extracts have the highest amount of stigmasterol (~23.4%) and β-sitosterol (~43%), and leaf extracts presented β-amyrin (16.3%). Methanolic leaf extracts showed mostly sugars and some polyols, mainly D-pinitol (74.3%). Compared with the intact plant, dichloromethane and fatty hexane extracts of CSC exhibited percentages of inhibition higher for Sclerotium cepivorum: 71.5% and 62.0%, respectively. The maximum inhibition for Rhizoctonia solani was with fatty hexane extracts of the sapwood (51.4%). Our study suggests that CSC extracts could be used as a possible complementary alternative to synthetic fungicides.

Targeted permeabilization of the cell wall and extraction of charged molecules from single cells in intact plant clusters using a focused electric field

Selective and direct extraction of charged molecules from single cells of intact plant clusters using a focused electric field.

Cannabidiol (CBD) Oil Does Not Display an Entourage Effect in Reducing Cancer Cell Viability in vitro

<b><i>Introduction:</i></b> Several studies have found that cannabinoids, particularly delta-9-tetrahydrocannabinol and cannabidiol (CBD), have the ability to reduce cancer cell viability. An ongoing debate regarding the use of medical Cannabis revolves around the effectiveness of pure compounds versus intact plant material for treatment. Proponents for the use of intact plant material or botanical extracts argue that there is a synergistic effect between the different cannabinoids, terpenoids, and flavonoids; this is commonly referred to as the “entourage effect.” Our study was designed to test the validity of the proposed entourage effect in a narrow application using a cancer cell viability model. <b><i>Materials and Methods:</i></b> Six cancer cell lines, from 3 different types of human cancer were treated with 10 μM pure CBD or 10 μM CBD from hemp (<i>Cannabis sativa</i>) oil (obtained from 3 different commercial sources) for 48 h, and cell viability was measured with the MTS assay. Dose-response curves were then performed to compare the potencies of pure CBD to CBD oils. CBD concentrations were independently confirmed in the commercial oils, and cannabinoid and terpene composition were also compared. <b><i>Results:</i></b> CBD (10 μM) was able to reduce cell viability in 3 of the 6 cell lines tested, and this was found to be cell line specific and not specific to select cancers. None of the CBD oils tested were able to reduce viability to a greater extent than that of pure CBD. Additionally, dose-response curves found lower IC₅₀ values for pure CBD compared to the most potent CBD oil tested. Interestingly, some oils actually appeared to protect cancer cells from the effects of CBD. <b><i>Conclusions:</i></b> We found that pure CBD was as potent or more potent at reducing cancer cell viability as the most potent oil tested, suggesting that there is no “entourage” effect under these specific in vitro conditions.

Carbon nanocarriers deliver siRNA to intact plant cells for efficient gene knockdown

Posttranscriptional gene silencing (PTGS) is a powerful tool to understand and control plant metabolic pathways, which is central to plant biotechnology. PTGS is commonly accomplished through delivery of small interfering RNA (siRNA) into cells. Standard plant siRNA delivery methods (Agrobacterium and viruses) involve coding siRNA into DNA vectors and are only tractable for certain plant species. Here, we develop a nanotube-based platform for direct delivery of siRNA and show high silencing efficiency in intact plant cells. We demonstrate that nanotubes successfully deliver siRNA and silence endogenous genes, owing to effective intracellular delivery and nanotube-induced protection of siRNA from nuclease degradation. This study establishes that nanotubes could enable a myriad of plant biotechnology applications that rely on RNA delivery to intact cells.