(85c) Tunability of Cell-Triggered DNA Release From a Substrate-Mediated Delivery System

The inherent limitations of bolus gene delivery may be avoided by surface immobilization of DNA onto biomaterial scaffolds. As an alternative to current immobilization approaches, we chemically bind plasmid DNA to a substrate via an enzymatically-labile peptide sequence, allowing for cell-responsive gene delivery. In our design, the DNA is functionalized using a peptide nucleic acid (PNA) clamp. Coupling peptides that include a matrix metalloproteinase-1 (MMP-1) degradable sequence are attached to this conjugate forming DNA-PNA-peptide (DPP) conjugates. In this work, we demonstrate the formation and immobilization to a model gold surface of the DPP conjugates. Transfection studies were completed with NIH/3T3 cells and the functionalized substrates to demonstrate MMP-1-responsive release of DNA from the surfaces. Currently, we are exploring the kinetics of conjugate release upon exposure to enzyme by surface plasmon resonance (SPR). We are investigating the tunability of the system in response to alterations in the number of DNA-surface tethers, alterations in the size of the polycation used during complexation, and decreased surface coverage of the DPP conjugates. Simultaneously, we are exploring whether alteration of the DPP conjugate design can improve the transfection efficiency.