Capsule-like Safe Genetic Vectors-Cell-Penetrating Core-Shell Particles Selectively Release Functional Small RNA and Entrap Its Encoding DNA

Polymeric Delivery of Therapeutic Nucleic Acids

The advent of genome editing has transformed the therapeutic landscape for several debilitating diseases, and the clinical outlook for gene therapeutics has never been more promising. The therapeutic potential of nucleic acids has been limited by a reliance on engineered viral vectors for delivery. Chemically defined polymers can remediate technological, regulatory, and clinical challenges associated with viral modes of gene delivery. Because of their scalability, versatility, and exquisite tunability, polymers are ideal biomaterial platforms for delivering nucleic acid payloads efficiently while minimizing immune response and cellular toxicity. While polymeric gene delivery has progressed significantly in the past four decades, clinical translation of polymeric vehicles faces several formidable challenges. The aim of our Account is to illustrate diverse concepts in designing polymeric vectors towards meeting therapeutic goals of in vivo and ex vivo gene therapy. Here, we highlight several classes of polymers employed in gene delivery and summarize the recent work on understanding the contributions of chemical and architectural design parameters. We touch upon characterization methods used to visualize and understand events transpiring at the interfaces between polymer, nucleic acids, and the physiological environment. We conclude that interdisciplinary approaches and methodologies motivated by fundamental questions are key to designing high-performing polymeric vehicles for gene therapy.

Improving the Activity of DNA-Encoded Sensing Elements through Confinement in Silk Microcapsules

Assembling synthetic bioparts into simplified artificial cells holds tremendous promise for advancing studies into the synthesis, biosensing, and delivery of biomolecules. Currently, the most successful techniques for encapsulation of the transcription-translation machinery exploit compartmentalization in liposomal vesicles. However, improvements to these methods may increase permeability to polar molecules, functionalization of the membrane with biologically active elements, and encapsulation efficiency. Microcapsules prepared via templated layer-by-layer (LbL) assembly using natural polymers have the potential to resolve some of the hurdles associated with liposomes. Here, we introduce a design for immobilizing DNA templates encoding translationally activated riboswitches and RNA aptamers into microcapsules prepared from regenerated silk fibroin protein. Adjusting several key parameters such as the presence of a polymer primer, concentration of silk protein, and DNA loadings during LbL assembly resulted in biocompatible, semipermeable, DNA-laden microcapsules. To preserve bioactivity, DNA was immobilized inside of the capsule membrane, which not only promoted stability during long-term storage at ambient conditions but also improved output response from spatially confined DNA-encoded sensing elements (SEs). Multiple copies of mRNA and GFPa1 protein were synthesized upon activation with specific analytes during in vitro transcription/translation reactions, demonstrating that selective permeability of silk microcapsules was essential for the diffusion of components of the cell-free system inside of the capsules. Further functionalization of capsule shells with gold nanoparticles (AuNPs) and antibodies (IgG) demonstrated the applicability of microcompartmentalized colloidal objects carrying SEs for remote sensing and/or targeted delivery. In the future, multifunctional, biocompatible silk-based microcapsules loaded with different RNA sensors can help advance the design of multiplexed biosensors tracking multiple biomarkers in complex media.