title: Highly Hybridizable Spherical Nucleic Acids by Tandem Glutathione Treatment and Polythymine Spacing.
abstract: Gold nanoparticle (AuNP)-templated spherical nucleic acids (SNAs) have been demonstrated as an important functional material in bionanotechnology. Fabrication of SNAs having high hybridization capacity to their complementary sequences is critical to ensure their applicability in areas such as antisense gene therapy and cellular sensing. The traditional salt-aging procedure is effective but tedious, requiring 1-3 days to complete. The rapid low-pH assisted protocol is efficient, but causes concerns related to nonspecific DNA adsorption to the AuNP core. To address these issues, we systematically compared the SNAs prepared by these two methods (salt-aging method and low-pH protocol). In terms of the number of complementary DNA that each SNA can bind and the average binding affinity of each thiolated DNA probe to its complementary strand, both methods yielded comparable hybridizability, although higher loading capacity was witnessed with SNAs made using the low-pH method. Additionally, it was found that nonspecific DNA binding could be eliminated almost completely by a simple glutathione (GSH) treatment of SNAs. Compared to conventional methods using toxic mercapto-hexanol or alkanethiols to remove nonspecific DNA adsorption, GSH is mild, cost-effective, and technically easy to use. In addition, GSH-passivated SNAs minimize the toxicity concerns related to AuNP-induced GSH depletion and therefore offer a more biocompatible alternative to previously reported SNAs. Moreover, rational design of probe sequences through inclusion of a polythymine spacer into the DNA sequences resulted in enhanced DNA loading capacity and stability against salt-induced aggregation. This work provides not only efficient and simple technical solutions to the issue of nonspecific DNA adsorption, but also new insights into the hybridizability of SNAs.
authors.affiliation: State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology , Beijing 100029, People's Republic of China.
authors.forename: Jing
authors.initials: J
authors.lastname: Sun
authors.affiliation: Verschuren Centre for Sustainability in Energy and the Environment, Cape Breton University , 1250 Grand Lake Road, Sydney, Nova Scotia B1P 6L2, Canada.
authors.forename: Dennis
authors.initials: D
authors.lastname: Curry
authors.affiliation: State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology , Beijing 100029, People's Republic of China.
authors.forename: Qipeng
authors.initials: Q
authors.lastname: Yuan
authors.affiliation: Verschuren Centre for Sustainability in Energy and the Environment, Cape Breton University , 1250 Grand Lake Road, Sydney, Nova Scotia B1P 6L2, Canada.
authors.forename: Xu
authors.initials: X
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology , Beijing 100029, People's Republic of China.
authors.forename: Hao
authors.initials: H
authors.lastname: Liang
mesh_terms: D015342:DNA Probes / Q000737:chemistry*; D005978:Glutathione / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D053768:Metal Nanoparticles / Q000737:chemistry*; D009693:Nucleic Acid Hybridization / Q000379:methods; D011071:Poly T / Q000737:chemistry*
chemical_list: D015342:DNA Probes; D011071:Poly T; D006046:Gold; D005978:Glutathione
keywords: glutathione; gold nanoparticles; hybridizability; polythymine spacer; spherical nucleic acids