Bottom-Up Strategy To Prepare Nanoparticles with a Single DNA Strand

Abstract

We describe the preparation of cross-linked, polymeric organic nanoparticles (ONPs) with a single, covalently linked DNA strand. The structure and functionalities of the ONPs are controlled by the synthesis of their parent linear block copolymers that provide monovalency, fluorescence and narrow size distribution. The ONP can also guide the deposition of chloroaurate ions allowing gold nanoparticles (AuNPs) to be prepared using the ONPs as templates. The DNA strand on AuNPs is shown to preserve its functions.

Figure 1

Schematic showing the stepwise, bottom-up synthesis of monovalent DNA-NP conjugate using single-chain block copolymer as template.

Figure 2

Scheme showing structures of the functional monomers and the detailed, ROMP-based synthesis of monovalent ONP-N₃. 2 and 6 = Grubbs catalysts (3^rd and 1^st generation). 4 = tris[(allyloxy)methyl]aminomethane.

Figure 3

(a) Negatively-stained and bright-field (insert) TEM images of azido-ONPs. Scale bar = 50 nm. (b) AFM images of ONPs. (c) Scheme showing the DNA-ONP conjugation chemistry. (d) Elution profiles of the mixture of DNA and ONP, and the DNA-ONP conjugate. (e) TEM images of heterogeneous dimers from monovalent DNA-ONP and 10 nm AuNP. (f) Fluorescence titration curve showing approximate 1:1 ratio of DNA to ONP in the conjugates.

Figure 4

(a) Scheme showing a possible mechanism for the template AuNP-DNA synthesis. (b) Kinetic study of the AuNP formation using UV-vis and fluorescence spectroscopy. (c) TEM images of the AuNP@ONP. (d) STEM and EDX element mapping images of AuNP@ONP. (e) Hybridization-mediated MNP dimerization using the mono-DNA AuNP@ONP with commercial 10 nm AuNP functionalized with complimentary DNA strands. (f) Fluorescence titration curves of mono-DNA AuNP@ONP.