L-DNA Oligonucleotide Exchange Enables the Replenishment of Coatings on Blood-Contacting Devices

Abstract

The aim of this project was to determine if L-DNA oligonucleotide toehold exchange would be a viable mechanism for developing refillable anti-thrombogenic coatings for blood-contacting devices. Medical devices that interface with blood, such as catheters and stents, are susceptible to thrombus formation which can limit the lifespan of the device and lead to dangerous patient outcomes. Anti-thrombogenic coatings have been developed to address this problem, but their efficacy is limited by the degradation of these coatings over time; therefore, a system in which degraded coatings could be replenished would increase the longevity of these devices. One such system using toehold mediated oligonucleotide exchange has been described. In this system, two oligonucleotide strands, one carrying an anti-thrombotic agent as a payload, are immobilized on the surface of the device. When this anti- thrombotic agent degrades, a third strand carrying a fresh payload is introduced displacing the previous strand. This process of strand replacement can be repeated with either strand. While this system is promising, it is potentially limited by degradation of oligonucleotide strands by circulating nucleases. In this study, DNA and L-DNA, a mirror-image form of DNA with greater stability from enzymatic degradation, were fluorescently labeled in order to study the kinetics of strand replacement reactions. DNA and L-DNA oligonucleotides were also treated with nuclease solutions, whole blood, and serum to investigate their stability in these contexts. Both DNA and L-DNA strands showed similar abilities to perform multiple strand replacements. Furthermore, these replacements occurred in timescales compatible with their intravenous delivery and predicted plasma half-life times. Additionally, the use of L-DNA oligonucleotides significantly improved stability when exposed to nuclease solutions or serum when compared to DNA. These findings suggest that L-DNA oligonucleotide replacement represents a promising strategy for refilling anti-thrombogenic coatings of blood-contacting devices.