Uptake and Bioactivity of Chitosan/Double-Stranded RNA Polyplex Nanoparticles in Caenorhabditis elegans

Nanoparticle-mediated dsRNA delivery for precision insect pest control: a comprehensive review

Nanoparticle-based delivery systems have emerged as powerful tools in the field of pest management, offering precise and effective means of delivering double-stranded RNA (dsRNA), a potent agent for pest control through RNA interference (RNAi). This comprehensive review aims to evaluate and compare various types of nanoparticles for their suitability in dsRNA delivery for pest management applications. The review begins by examining the unique properties and advantages of different nanoparticle materials, including clay, chitosan, liposomes, carbon, gold and silica. Each material's ability to protect dsRNA from degradation and its potential for targeted delivery to pests are assessed. Furthermore, this review delves into the surface modification strategies employed to enhance dsRNA delivery efficiency. Functionalization with oligonucleotides, lipids, polymers, proteins and peptides is discussed in detail, highlighting their role in improving stability, cellular uptake, and specificity of dsRNA delivery.This review also provides valuable guidance on choosing the most suitable nanoparticle-based system for delivering dsRNA effectively and sustainably in pest management. Moreover, it identifies existing knowledge gaps and proposes potential research directions aimed at enhancing pest control strategies through the utilization of nanoparticles and dsRNA.

Chitosan/dsRNA polyplex nanoparticles advance environmental RNA interference efficiency through activating clathrin-dependent endocytosis

Chitosan, as a promising gene nanocarrier for enhancing RNA interference (RNAi) efficiency, displays tremendous application prospects in addressing dsRNA delivery concerns. However, the molecular mechanism of chitosan/dsRNA polyplex nanoparticles (PNs) for advancing dsRNA delivery efficiency remains largely unknown. Here, chitosan/dsRNA PNs were prepared by an electrostatic attraction method. The results showed that the chitosan/dsRNA PNs significantly advance stability, and cellular uptake efficiency of dsRNA, and RNAi efficiency. RNA-Seq and qPCR assays further revealed that chitosan/dsRNA PNs upregulated the key clathrin heavy chain (CHC) gene for activating clathrin-dependent endocytosis (CDE) pathway. Additionally, inhibition of CDE hindered the robust RNAi responses of chitosan/dsRNA PNs using an inhibitor (chlorpromazine) and an RNAi-of-RNAi strategy. Ultimately, microscale thermophoresis assay confirmed that chitosan/dsRNA PNs directly bound to CHC protein, which was a core component in CDE, to advance RNAi efficiency. To our knowledge, our findings firstly illuminate the molecular mechanism how chitosan nanoparticles-based RNAi deliver dsRNA for enhancing RNAi efficiency. Above mechanism will advance the extensive utilization of nanocarrier-based RNAi in pest management and gene delivery.

Activity of chitin/chitosan/chitosan oligosaccharide against plant pathogenic nematodes and potential modes of application in agriculture: A review

Chemical nematicide is the most common method of controlling plant-parasitic nematodes (PPN). Given the negative impact of chemical nematicides on the environment and ecosystem, it is necessary to seek their alternatives and novel modes of application. Chitin oligo/polysaccharide (COPS), including chitosan and chitosan oligosaccharide, has unique biological properties. By producing ammonia, encouraging the growth of antagonistic bacteria, and enhancing crop tolerance, COPSs help suppress PPN growth during soil remediation. COPS is also an effective sustained-release carrier that can be used to overcome the shortcomings of nematicidal substances. This review summarizes the advancements of COPS research in nematode control from three perspectives of action mechanism as well as in slow-release carrier-loaded nematicides. Further, it discusses potential agricultural applications for nematode disease management.

Recent Progress on Nanocarriers for Topical-Mediated RNAi Strategies for Crop Protection—A Review

To fulfil the growing needs of the global population, sustainability in food production must be ensured. Insect pests and pathogens are primarily responsible for one-third of food losses and harmful synthetic pesticides have been applied to protect crops from these pests and other pathogens such as viruses and fungi. An alternative pathogen control mechanism that is more “friendly” to the environment can be developed by externally applying double-stranded RNAs (dsRNAs) to suppress gene expression. However, the use of dsRNA sprays in open fields is complicated with respect to variable efficiencies in the dsRNA delivery, and the stability of the dsRNA on and in the plants, and because the mechanisms of gene silencing may differ between plants and between different pathogen targets. Thus, nanocarrier delivery systems have been especially used with the goal of improving the efficacy of dsRNAs. Here, we highlight recent developments in nanoparticle-mediated nanocarriers to deliver dsRNA, including layered double hydroxide, carbon dots, carbon nanotubes, gold nanoparticles, chitosan nanoparticles, silica nanoparticles, liposomes, and cell-penetrating peptides, by review of the literature and patent landscape. The effects of nanoparticle size and surface modification on the dsRNA uptake efficiency in plants are also discussed. Finally, we emphasize the overall limitation of dsRNA sprays, the risks associated, and the potential safety concerns for spraying dsRNAs on crops.

Tanshinone IIA loaded chitosan nanoparticles decrease toxicity of β-amyloid peptide in a Caenorhabditis elegans model of Alzheimer's disease

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases that characterized by the accumulation of β-amyloid peptide (Aβ). Overexpressions of Aβ could induce oxidative stress that might be a key insult to initiate the cascades of Aβ accumulation. As a result, anti-oxidative stress and attenuating Aβ accumulation might be one promising intervention for AD treatment. Tanshinone IIA (Tan IIA), a major component of lipophilic tanshinones in Danshen, is proven to be effective in several diseases, including AD. Due to the poor solubility in water, the clinical application of Tan IIA was limited. Therefore, a great number of nanoparticles were designed to overcome this issue. In the current study, we choose chitson as delivery carrier to load Tanshinone IIA (CS@Tan IIA) and explore the protective effects of CS@Tan IIA on the CL2006 strain, a transgenic C. elegans of AD model organism. Compared with Tan IIA monomer, CS@Tan IIA could significantly prolong the lifespan and attenuate the AD-like symptoms, including reducing paralysis and the Aβ deposition by inhibiting the oxidative stress. The mechanism study showed that the protection of CS@Tan IIA was attenuated by knockdown of daf-16 gene, but not skn-1. The results indicated that DAF-16/SOD-3 pathway was required in the protective effects of CS@Tan IIA. Besides DAF-16/SOD-3 pathway, the Tan IIA-loaded CS nanoparticles might protect the C. elegans against the AD insults via promoting autophagy. All the results consistently suggested that coating by chitosan could improve the solubility of Tan IIA and effectively enhance the protective effects of Tan IIA on AD, which might provide a potential drug loading approach for the hydrophobic drugs as Tan IIA.

Management of Post-Harvest Anthracnose: Current Approaches and Future Perspectives

Anthracnose is a severe disease caused by Colletotrichum spp. on several crop species. Fungal infections can occur both in the field and at the post-harvest stage causing severe lesions on fruits and economic losses. Physical treatments and synthetic fungicides have traditionally been the preferred means to control anthracnose adverse effects; however, the urgent need to decrease the use of toxic chemicals led to the investigation of innovative and sustainable protection techniques. Evidence for the efficacy of biological agents and vegetal derivates has been reported; however, their introduction into actual crop protection strategies requires the solutions of several critical issues. Biotechnology-based approaches have also been explored, revealing the opportunity to develop innovative and safe methods for anthracnose management through genome editing and RNA interference technologies. Nevertheless, besides the number of advantages related to their use, e.g., the putative absence of adverse effects due to their high specificity, a number of aspects remain to be clarified to enable their introduction into Integrated Pest Management (IPM) protocols against Colletotrichum spp. disease.

coupled Hydrodynamic Flow Focusing (cHFF) to Engineer Lipid–Polymer Nanoparticles (LiPoNs) for Multimodal Imaging and Theranostic Applications

An optimal design of nanocarriers is required to overcome the gap between synthetic and biological identity, improving the clinical translation of nanomedicine. A new generation of hybrid vehicles based on lipid–polymer coupling, obtained by Microfluidics, is proposed and validated for theranostics and multimodal imaging applications. A coupled Hydrodynamic Flow Focusing (cHFF) is exploited to control the time scales of solvent exchange and the coupling of the polymer nanoprecipitation with the lipid self-assembly simultaneously, guiding the formation of Lipid–Polymer NPs (LiPoNs). This hybrid lipid–polymeric tool is made up of core–shell structure, where a polymeric chitosan core is enveloped in a lipid bilayer, capable of co-encapsulating simultaneously Gd-DTPA and Irinotecan/Atto 633 compounds. As a result, a monodisperse population of hybrid NPs with an average size of 77 nm, with preserved structural integrity in different environmental conditions and high biocompatibility, can be used for MRI and Optical applications. Furthermore, preliminary results show the enhanced delivery and therapeutic efficacy of Irinotecan-loaded hybrid formulation against U87 MG cancers cells.

Krüppel-homologue 1 Mediates Hormonally Regulated Dominance Rank in a Social Bee

Dominance hierarchies are ubiquitous in invertebrates and vertebrates, but little is known on how genes influence dominance rank. Our gaps in knowledge are specifically significant concerning female hierarchies, particularly in insects. To start filling these gaps, we studied the social bumble bee Bombus terrestris, in which social hierarchies among females are common and functionally significant. Dominance rank in this bee is influenced by multiple factors, including juvenile hormone (JH) that is a major gonadotropin in this species. We tested the hypothesis that the JH responsive transcription factor Krüppel homologue 1 (Kr-h1) mediates hormonal influences on dominance behavior. We first developed and validated a perfluorocarbon nanoparticles-based RNA interference protocol for knocking down Kr-h1 expression. We then used this procedure to show that Kr-h1 mediates the influence of JH, not only on oogenesis and wax production, but also on aggression and dominance rank. To the best of our knowledge, this is the first study causally linking a gene to dominance rank in social insects, and one of only a few such studies on insects or on female hierarchies. These findings are important for determining whether there are general molecular principles governing dominance rank across gender and taxa.

RNAi Crop Protection Advances

RNAi technology is a versatile, effective, safe, and eco-friendly alternative for crop protection. There is plenty of evidence of its use through host-induced gene silencing (HIGS) and emerging evidence that spray-induced gene silencing (SIGS) techniques can work as well to control viruses, bacteria, fungi, insects, and nematodes. For SIGS, its most significant challenge is achieving stability and avoiding premature degradation of RNAi in the environment or during its absorption by the target organism. One alternative is encapsulation in liposomes, virus-like particles, polyplex nanoparticles, and bioclay, which can be obtained through the recombinant production of RNAi in vectors, transgenesis, and micro/nanoencapsulation. The materials must be safe, biodegradable, and stable in multiple chemical environments, favoring the controlled release of RNAi. Most of the current research on encapsulated RNAi focuses primarily on oral delivery to control insects by silencing essential genes. The regulation of RNAi technology focuses on risk assessment using different approaches; however, this technology has positive economic, environmental, and human health implications for its use in agriculture. The emergence of alternatives combining RNAi gene silencing with the induction of resistance in crops by elicitation and metabolic control is expected, as well as multiple silencing and biotechnological optimization of its large-scale production.

Control of postharvest fungal diseases in fruits using external application of RNAi

Contamination with a variety of filamentous fungi can cause deterioration of food and agricultural products. Fungal contaminations reduce the quality and the shelf life of fresh fruits and are one of the main causes of economic loss in the global fresh fruit industry. Although chemical fungicides are effective and traditionally used to control postharvest fungal diseases, they are harmful to human health. In this context, use of RNA interference (RNAi)-based fungicides is a promising alternative strategy. Spray-induced gene silencing (SIGS) is an innovative RNAi-based approach for silencing target genes in phytopathogens. This review aims to discuss the recent findings on the use of RNAi-based fungicides to control the postharvest spoilage of fresh fruits. PRACTICAL APPLICATION: Control of postharvest fungal diseases is one of the most important strategies to make food available to consumers longer. In this sense, the external application of RNAi seems to be technologically advantageous and efficient as it helps to maintain the characteristics of plant products. In this sense, this review discussed what is possible to find in the literature regarding this new technology.

Cellular uptake of chitosan and its role in antifungal action against Penicillium expansum

Chitosan has wide-spectrum antimicrobial activity but knowledge of its antifungal mechanism is still incomplete. In this study, transcriptome of Penicillium expansum upon chitosan treatment was analyzed by RNA-Seq. KEGG enrichment analysis revealed that endocytosis as well as other physiological pathways was regulated by chitosan treatment. Clathrin adaptor protein mu-subunit (PeCAM) gene, which encodes a protein associated with clathrin-dependent endocytosis, was up-regulated after chitosan treatment. Deletion of PeCAM resulted in changes of conidial, hyphal and colonial morphology. Confocal microscopy images of the distribution of fluorescein isothiocyanate-labeled chitosan confirmed cellular internalization of chitosan. However, deletion of PeCAM almost completely blocked uptake of chitosan into fungal cells and ΔPeCAM mutant exhibited less sensitivity to chitosan compared with wild type, suggesting that chitosan uptake is mediated by clathrin-dependent endocytosis and internalized chitosan also plays an important role in its antifungal activity. Collectively, our results provide a new insight into the antifungal mechanism of chitosan.

RNA Interference Strategies for Future Management of Plant Pathogenic Fungi: Prospects and Challenges

Plant pathogenic fungi are the largest group of disease-causing agents on crop plants and represent a persistent and significant threat to agriculture worldwide. Conventional approaches based on the use of pesticides raise social concern for the impact on the environment and human health and alternative control methods are urgently needed. The rapid improvement and extensive implementation of RNA interference (RNAi) technology for various model and non-model organisms has provided the initial framework to adapt this post-transcriptional gene silencing technology for the management of fungal pathogens. Recent studies showed that the exogenous application of double-stranded RNA (dsRNA) molecules on plants targeting fungal growth and virulence-related genes provided disease attenuation of pathogens like Botrytis cinerea, Sclerotinia sclerotiorum and Fusarium graminearum in different hosts. Such results highlight that the exogenous RNAi holds great potential for RNAi-mediated plant pathogenic fungal disease control. Production of dsRNA can be possible by using either in-vitro or in-vivo synthesis. In this review, we describe exogenous RNAi involved in plant pathogenic fungi and discuss dsRNA production, formulation, and RNAi delivery methods. Potential challenges that are faced while developing a RNAi strategy for fungal pathogens, such as off-target and epigenetic effects, with their possible solutions are also discussed.

Comparison of strategies for enhancing RNA interference efficiency in Ostrinia nubilalis

BACKGROUND

Targeting insect-specific genes through post-transcriptional gene silencing with RNA interference (RNAi) is a new strategy for insect pest management. However, lepidopterans are recalcitrant to RNAi, which prevents application of novel RNAi technology to many notorious pests, including Ostrinia nubilalis (ECB). Strategies for enhancing RNAi efficiency, including large doses of double-stranded RNA (dsRNA), nuclease inhibitors, transfection reagents, and nanoparticles, have proved useful in other insects exhibiting substantial dsRNA degradation, a major mechanism limiting RNAi efficacy. To determine if similar strategies can enhance RNAi efficiency in ECB, various reagents were tested for their ability to enhance dsRNA stability in ECB tissues, then compared for their effectiveness in whole ECB.

RESULTS

Ex vivo incubation experiments revealed that Meta dsRNA lipoplexes, EDTA, chitosan-based dsRNA nanoparticles, and Zn²⁺ enhanced dsRNA stability in ECB hemolymph and gut content extracts, compared with uncoated dsRNA. Despite these positive results, the reagents used in this study were ineffective at enhancing RNAi efficiency in ECB in vivo. To reduce assay time and required dsRNA, midguts were dissected and incubated in tissue culture medium containing dsRNA with and without reagents. These experiments showed that RNAi efficiency varied between target genes, and nuclease inhibitors improved RNAi efficiency for only a portion of the refractory target genes investigated ex vivo.

CONCLUSION

These results indicate that enhancing dsRNA stability is insufficient to improve RNAi efficiency in ECB and suggests the existence of additional, complex mechanisms contributing to low RNAi efficiency in ECB.

Comparison of Nanomaterials for Delivery of Double-Stranded RNA in Caenorhabditis elegans

RNA interference is a promising crop protection technology that has seen rapid development in the past several years. Here, we investigated polyamino acid biopolymers, inorganic nanomaterials, and hybrid organic-inorganic nanomaterials for delivery of dsRNA and efficacy of gene knockdown using the model nematode Caenorhabditis elegans. Using an oral route of delivery, we are able to approximate how nanomaterials will be delivered in the environment. Of the materials investigated, only Mg-Al layered double-hydroxide nanoparticles were effective at gene knockdown in C. elegans, reducing marker gene expression to 66.8% of that of the control at the lowest tested concentration. In addition, we identified previously unreported injuries to the mouthparts of C. elegans associated with the use of a common cell-penetrating peptide, poly-l-arginine. Our results will allow the pursuit of further research into promising materials for dsRNA delivery and also allow for the exclusion of those with little efficacy or deleterious effects.

Polymer-Coated Hydroxyapatite Nanocarrier for Double-Stranded RNA Delivery

Conventional synthetic insecticides have limited success due to insect resistance and negative effects on off-target biota and the environment. Although RNA interference (RNAi) is a tool that is becoming more widely utilized in pest control products, naked dsRNA has limited success in most taxa. Nanocarriers have shown promising results in enhancing the efficacy of this tool. In this study, we used a layer-by-layer electrostatic assembly where we synthesized poly(acrylic acid) (PAA)-coated hydroxyapatite (HA) nanoparticles (PAA-HA NPs) as inorganic nanocarriers, which were then coated with a layer of a cationic poly(amino acid), 10 kDa poly-l-arginine (PLR₁₀), to allow for binding of a layer of negatively charged dsRNA. Binding of PLR₁₀-PAA-HA NPs to dsRNA was found to increase as the mass ratio of NPs to dsRNA increased. In vitro studies with transgenic SF9 cells (from Spodoptera frugiperda) expressing the firefly luciferase gene showed a significant gene silencing (35% decrease) at a 5:1 NP-to-dsRNA ratio, while naked dsRNA was ineffective at gene silencing. There was a significant concentration-response relationship in knockdown; however, cytotoxicity was observed at higher concentrations. Confocal microscopy studies showed that dsRNA from PLR₁₀-PAA-HA NPs was not localized within endosomes, while naked dsRNA appeared to be entrapped within the endosomes. Overall, polymer-functionalized HA nanocarriers enabled dsRNA to elicit gene knockdown in cells, whereas naked dsRNA was not effective in causing gene knockdown.

Endocytosis: The Nanoparticle and Submicron Nanocompounds Gateway into the Cell

Nanoparticles (NPs) and submicron particles are increasingly used as carriers for delivering therapeutic compounds to cells. Their entry into the cell represents the initial step in this delivery process, being most of the nanoparticles taken up by endocytosis, although other mechanisms can contribute to the uptake. To increase the delivery efficiency of therapeutic compounds by NPs and submicron particles is very relevant to understand the mechanisms involved in the uptake process. This review covers the proposed pathways involved in the cellular uptake of different NPs and submicron particles types as well as the role that some of the physicochemical nanoparticle characteristics play in the uptake pathway preferentially used by the nanoparticles to gain access and deliver their cargo inside the cell.