期刊
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
卷 137, 期 10, 页码 3486-3489出版社
AMER CHEMICAL SOC
DOI: 10.1021/jacs.5b00670
关键词
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资金
- AFOSR [FA9550-09-1-0294, FA9550-11-1-0275, FA9550-12-1-0280]
- DARPA [HR0011-13-2-0018]
- Center for Cancer Nanotechnology Excellence initiative of the NIH [U54 CA151880]
- NSF's MRSEC program at the Materials Research Center of Northwestern University [DMR-1121262]
- NSF
The hybridization of free oligonucleotides to densely packed, oriented arrays of DNA modifying the surfaces of spherical nucleic acid (SNA)-gold nanoparticle conjugates occurs with negative cooperativity; i.e., each binding event destabilizes subsequent binding events. DNA hybridization is thus an ever-changing function of the number of strands already hybridized to the particle. Thermodynamic quantification of this behavior reveals a 3 orders of magnitude decrease in the binding constant for the capture of a free oligonucleotide by an SNA conjugate as the fraction of pre-hybridized strands increases from 0 to similar to 30%. Increasing the number of pre-hybridized strands imparts an increasing enthalpic penalty to hybridization that makes binding more difficult, while simultaneously decreasing the entropic penalty to hybridization, which makes binding more favorable. Hybridization of free DNA to an SNA is thus governed by both an electrostatic barrier as the SNA accumulates charge with additional binding events and an effect consistent with allostery, where hybridization at certain sites on an SNA modify the binding affinity at a distal site through conformational changes to the remaining single strands. Leveraging these insights allows for the design of conjugates that hybridize free strands with significantly higher efficiencies, some of which approach 100%.
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