There have been many important applications involving the delivery of RNA to cells in recent years. Among the most prominent is delivery of mRNA to human cells for vaccination against the SARS-CoV-2 virus. These vaccines generally utilize lipid-based nanoparticles to deliver modified mRNA. However, there are other important applications of RNA delivery, such as those for biocontrol of insect pests using RNA interference (RNAi). We have investigated the use of polyplex nanoparticles and composite organic-polymer nanoparticles for the delivery of long double stranded RNA (dsRNA) and short hairpin RNA (shRNA). Initially, experiments using <i>Caenorhabditis elegans</i> as a model organism have provided some insights into the mechanisms of dsRNA delivery and the influence of environmental variables on efficacy. We then used cell-culture based assays (SF9 cells, from the fall armyworm) to screen for off-target toxicity and efficacy of a variety of polyplex and composite nanoparticle delivery vehicles. Our results demonstrated that particle charge, size and nano-composite stability are key factors governing efficacy. Polymer composition was an important determinant of off-target toxicity. Finally, we demonstrate the oral delivery of shRNA in the neotropical stinkbug (<i>Euschistus heros</i>), an important pest of soybean in South America, using a composite inorganic-polymer nanomaterial (diethylamioethyldextran-coated cerium dioxide). There are several advantages to using shRNA versus mRNA for insect biocontrol, however; unlike dsRNA, shRNA has never been shown to have activity following oral administration in an insect. This was the first successful efficacious oral delivery of shRNA in vivo in an insect. Our results showed significant knockdown of a target gene and reduced survival time of the stinkbugs.

Use of manufactured nanomaterials for delivery of RNA to invertebrates: Applications for biocontrol of insect pests

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ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.