Formulation of DNA Nanocomposites: Towards Functional Materials for Protein Expression

DNA hydrogels are an emerging class of materials that hold great promise for numerous biotechnological applications, ranging from tissue engineering to targeted drug delivery and cell-free protein synthesis (CFPS). In addition to the molecular programmability of DNA that can be used to instruct biological systems, the formulation of DNA materials, e.g., as bulk hydrogels or microgels, is also relevant for specific applications. To advance the state of knowledge in this research area, the present work explores the scope of a recently developed class of complex DNA nanocomposites, synthesized by RCA polymerization of DNA-functionalized silica nanoparticles (SiNPs) and carbon nanotubes (CNTs). SiNP/CNT-DNA composites were produced as bulk materials and microgels which contained a plasmid with transcribable genetic information for a fluorescent marker protein. Using confocal microscopy and flow cytometry, we found that the materials are very efficiently taken up by various eukaryotic cell lines, which were able to continue dividing while the ingested material was evenly distributed to the daughter cells. However, no expression of the encoded protein occurred within the cells. While the microgels did not induce production of the marker protein even in a CFPS procedure with eukaryotic cell lysate, the bulk composites proved to be efficient templates for CFPS. This work contributes to the understanding of the molecular interactions between DNA composites and the functional cellular machinery. Implications for the use of such materials for CFPS procedures are discussed.