Catalytic Deoxyribozyme-Modified Nanoparticles for RNAi-Independent Gene Regulation

• Authors: Kevin Yehl, Emory University; Jayashree P. Joshi, Emory University; Brandon L. Greene, Emory University; Brian Dyer, Emory University; Rita Nahta, Emory University; Khalid Salaita, Emory University
• Journal Title: ACS Nano
• Volume: Volume 6, Number 10
• Publisher: American Chemical Society | 2012-10-23, Pages 9150-9157
• Type of Work: Article | Post-print: After Peer Review
• Publisher DOI: http://doi.org/10.1021/nn3034265
• Subjects: Health Sciences, Oncology; Biology, Genetics; Chemistry, Biochemistry
• Keywords: Deoxyribozyme; DNAzyme; gold nanoparticle; gene regulation; GDF15; Herceptin; trastuzumab; breast cancer; synthetic biology

Abstract

DNAzymes are catalytic oligonucleotides with important applications in gene regulation, DNA computing, responsive soft materials, and ultrasensitive metal-ion sensing. The most significant challenge for using DNAzymes in vivo pertains to non-toxic delivery and maintaining function inside cells. We synthesized multivalent deoxyribozyme ‘10–23’ gold nanoparticle (DzNP) conjugates, varying DNA density, linker length, enzyme orientation, and linker composition in order to study the role of the steric environment and gold surface chemistry on catalysis. DNAzyme catalytic efficiency was modulated by steric packing and proximity of the active loop to the gold surface. Importantly, the 10–23 DNAzyme was asymmetrically sensitive to the gold surface, and when anchored through the 5′ terminus was inhibited 32-fold. This property was used to generate DNAzymes whose catalytic activity is triggered by thiol displacement reactions or by photoexcitation at λ = 532 nm. Importantly, cell studies revealed that DzNPs are less susceptible to nuclease degradation, readily enter mammalian cells, and catalytically down-regulate GDF15 gene expression levels in breast cancer cells, thus addressing some of the key limitations in the adoption of DNAzymes for in vivo work.