DNA Nanostructures and DNA-Functionalized Nanoparticles for Cancer Theranostics

Abstract

In the last two decades, DNA has attracted significant attention toward the development of materials at the nanoscale for emerging applications due to the unparalleled versatility and programmability of DNA building blocks. DNA-based artificial nanomaterials can be broadly classified into two categories: DNA nanostructures (DNA-NSs) and DNA-functionalized nanoparticles (DNA-NPs). More importantly, their use in nanotheranostics, a field that combines diagnostics with therapy via drug or gene delivery in an all-in-one platform, has been applied extensively in recent years to provide personalized cancer treatments. Conveniently, the ease of attachment of both imaging and therapeutic moieties to DNA-NSs or DNA-NPs enables high biostability, biocompatibility, and drug loading capabilities, and as a consequence, has markedly catalyzed the rapid growth of this field. This review aims to provide an overview of the recent progress of DNA-NSs and DNA-NPs as theranostic agents, the use of DNA-NSs and DNA-NPs as gene and drug delivery platforms, and a perspective on their clinical translation in the realm of oncology.

Keywords: DNA‐nanostructures; cancer; nanoparticles; theranostics.

Figure 1

Different nanoscale shapes developed by DNA origami technology with dangling curves and loops representing unfolded sequences (top row). Diagrams demonstrate the bends at, and away, from crossovers (second row). Colors illustrate the base‐pair index along the folding path where red refers to the 1st base and purple refers to the 7000th base. AFM images of the DNA origami structures are also shown (third row). All image are the same size of 165 nm × 165 nm. Reproduced with permission.^{[ 40 ]} Copyright 2006, Springer Nature.

Figure 2

DNA origami nanostructures with complex 3D curvatures. Schematic representations of the hemisphere and corresponding transmission electron microscope (TEM) images of a,d) the hemisphere, b,e) the sphere, and c,f) the ellipsoid. Associated scale bars for the TEM images in (d)–(f) are 50 nm. g) Schematic representation of the nanoflask with expected dimensions. h) AFM images of the nanoflask in which the scale bar represents 75 nm. i) Negatively stained TEM images of the nanoflask, scale bar is 50 nm. Reproduced with permission.^{[ 41c ]} Copyright 2011, American Association for the Advancement of Science.

Figure 3

3D meshes rendered in DNA with different views of the 3D meshes serving as starting points for the initial design process. a) 3D meshes of different structures. b) The front face of each design. Single DNA strands are rendered as tubes. c–e) Negative‐stain dry‐state TEM images (except for the ball and bunny in (e) and (f), respectively) of each of the structures. Scale bars are as follows: c) 250 nm × 250 nm views; d,e) 100 nm × 100 nm close‐ups, with the exception of the pentagonal rod (200 nm × 100 nm); e,f) (ball and bunny) are imaged using cryo‐electron microscopy. The Au particle used for alignment is shown in (f). In (f), the scale bar represents 50 nm. Reproduced with permission.^{[ 43c ]} Copyright 2015, Springer Nature.

Figure 4

Synthesis of a DNA‐NP. A high‐density DNA‐NP is formed by using citrate‐stabilized particles incubated in alkylthiol‐functionalized DNA in water which consequently forms a low‐density monolayer. When the NPs are incubated in aqueous solutions with successively higher concentrations of salt (typically 0.15−1.0 m) and surfactants over ≈12 h, successful formation of a high‐density DNA‐NP shell is achieved. Reproduced with permission.^{[ 30c]} Copyright 2012, American Chemical Society.

Figure 5

Schematic illustration of the fate of bare and coated DNA‐NS in buffers (physiological pH) at 37 °C containing either low salt or 10% fetal bovine serum (FBS). At low salt concentrations, bare DNA‐NSs rapidly become denatured and degraded in cell medium containing 10% FBS. However, it is possible to override low‐salt‐induced denaturation and nuclease degradation through coating the DNA‐NSs with various ratios of positively charged peptides (K10 or K10–PEG5K). Reproduced under the terms of the Creative Commons Attribution License.^{[ 65 ]} Copyright 2017, Springer Nature.

Figure 6

Schematic and theranostic activity of the DNA nanotriangle structure. By conjugating the DNA nanotriangle scaffold and multiple split activable aptamer probes (SAAPs), via a–c) three exterior strands and d) an inner strand, the DNA nanostructure is formed. In the free state, the DNA nanotriangle, which is loaded with DOX via the CG base pair regions is a flat, double helix‐jointed structure with no fluorescence since it is quenched. Once it encounters the target cell, the aptamers disassemble and consequentially change shape. This leads to fluorescence emission and partial drug release with the remaining drugs being freed following internalization. Reproduced under the terms of the Creative Commons Attribution License.^{[ 80 ]} Copyright 2018, Ivyspring International Publisher.

Figure 7

Schematic representation of the synthesis of CACH‐PEG and its effects in vivo. a) Hemin and Ce6 are inserted into the G‐quadruplex structure. Mixing of the G‐quadruplex structure and Ca²⁺ together with pHis‐PEG yields Ca‐AS1411/Ce6/hemin@pHis‐PEG(CACH‐PEG) NCPs, which are pH responsive at ≈5.5 and were reduced to smaller G‐quadruplex complexes in acidic environments of the lyso‐ and endosomes. b) The tumor growth curves of 4T1‐tumor‐bearing mice following each treatment as indicated. Tumors were irradiated using 660 nm light‐emitting diode light (5 mW cm⁻²) for 60 min. c) Average tumor weights collected from the each group following 14 days after each treatment. Reproduced with permission.^{[ 90 ]} Copyright 2018, American Chemical Society.

Figure 8

Demonstration of the efficiency of photothermal therapy using either AuNR or DOX–AuNR. a) Cell viability of 4T1‐fLuc tumor cells following administration of varying treatments followed by NIR laser irradiation (808 nm, 1.5 W cm⁻², 3 min) (**p < 0.01, ***p < 0.0001). b) IR thermographic maps of each group of mice obtained 10 min after NIR irradiation. c) Bioluminescence imaging (BLI) of 4T1‐fLuc‐tumor‐bearing mice intravenously injected with PBS (control), AuNR and D–AuNR in combination with NIR laser irradiation acquired prior to injection and at days 0, 4, 7, 10, and 17. d) Survival rates of each group of mice following treatment were monitored 30 days post‐injection. Reproduced with permission.^{[ 91 ]} Copyright 2016, WILEY‐VCH.

Figure 9

a) Fluorescence imaging of HepG2 tumor‐bearing mice injected with either Ce6‐fDNADOX or Ce6‐fNDNADOX. Time lapse fluorescence images of Ce6 in vivo confirm tumor uptake. b) White light and fluorescence images of different organs removed from HepG2 tumor‐bearing mice 2 h post‐injection of either Ce6‐fDNADOX or Ce6‐fNDNADOX where Ce6 is represented in red and DOX in green. c) Tumor volume of mice (n = 5) after single IV injection of the indicated treatments. Tumors were imaged 2 h after injection by irradiation with 670 nm light (0.2 W cm⁻²) for 10 min. d) Average body weight of mice following each treatment (n = 5). Reproduced under the terms of the Creative Commons Attribution License.^{[ 93 ]} Copyright 2017, WILEY‐VCH.

Figure 10

DNA‐NPs distributed throughout glioma tissue. a) Quantification of DNA‐NP uptake into orthotopic U87MG tumor and adjacent normal tissue at 48 h post‐injection using inductively coupled plasma mass spectrometry (ICP‐MS). b) Schematic of the synthesis of Gd(III)‐functionalized DNA‐NPs. c) Accumulation of Gd(III)‐DNA‐NPs within the intracerebral lesion is confirmed using magnetic resonance imaging (MRI), hematoxylin and eosin staining, and 3D reconstructions. d) Localization of Au, Fe, and Gd(III) contents in coronal brain sections of mice injected intracranially with Gd(III)‐DNA‐NPs as confirmed by LA‐ICP‐MS. e) Confocal fluorescence microscopy of coronal brain sections derived from tumor‐ and nontumor‐bearing mice following saline or Cy5‐DNA‐NP injection. Reproduced with permission.^{[ 96a ]} Copyright 2013, American Association for the Advancement of Science.

Figure 11

a–c) X‐ray image, axial CT image, and fluorescence image of the CL1‐5 tumor‐bearing mouse taken 30 min post‐injection of aptamer‐targeted AuNPs as indicated by the yellow circle, white arrow, and yellow circle, respectively. d) CL1‐5 tumors under white light (top) and UV light (bottom). e) CL1‐5 tumors incubated without and with aptamers. f) Calculated total photon fluxes. Reproduced under the terms of the Creative Commons Attribution License.^{[ 103 ]} Copyright 2015, Springer Nature.

Figure 12

a) Schematic illustration of MUC1‐functionalized SERS NPs. b) The MUC1 aptamer‐functionalized DNA‐NPs were administered intravenously to human breast cancer tumor‐bearing mice and selectively targeted the tumors over‐expressing MUC1. Their accumulation within tissue was confirmed via identification of the “fingerprint” spectral signature of the SERS NPs using Raman spectroscopy. Reproduced with permission.^{[ 106 ]} Copyright 2017, WILEY‐VCH.

Figure 13

Conceptual figure illustrating the use of a nanobody (Nb)‐conjugated DNA‐NS for the delivery of the intercalating chemotherapeutic, 56MESS, where Nb, nanobody; TET, double‐bundle DNA tetrahedron; Nb‐TET, Nb‐conjugated double‐bundle DNA tetrahedron; Nb‐TET‐56MESS, platinum‐drug‐loaded NbTET; EGFR, epidermal growth factor receptor. Reproduced with permission.^{[ 119 ]} Copyright 2019, WILEY‐VCH.

Figure 14

a,b) Schematic of the synthesis, self‐assembly, and theranostic potential of the DNA‐NSs for anticancer treatment. c,d) In vivo tumor targeting and biodistribution of each DNA‐NS formulation following administration. e) Semiquantitative analysis of fluorescence signals in tumors at 1, 4, 8, and 24 h time points. Reproduced with permission.^{[ 124 ]} Copyright 2019, WILEY‐VCH.

Figure 15

Schematic illustration of the formation of multilayer Dox/D2/MoS2‐NS and subsequent intracellular release of DOX in which ATP‐aptamers enable layer‐by‐layer assembly. DOX is loaded within the multilayer structure. Cellular uptake is achieved through endocytosis and ATP‐induced DOX release occurs in the cytosol. Reproduced with permission.^{[ 127 ]} Copyright 2017, American Chemical Society.

Figure 16

Dimer loaded with DOX (Drug 1) and mitoxantrone (Drug 2) (left). Both DOX and mitoxantrone have fluorescent properties, which are quenched due to the close proximity to the AuNP core. Drug release is achieved following binding of target mRNA to the sense strand. Target mRNA can bind to the corresponding sense sequence via competitive hybridization to induce displacement of the flare strand. Displacement is observed as an increase in fluorescence at a wavelength specific to that of the fluorophore. Reproduced with permission.^{[ 132 ]} Copyright 2018, American Chemical Society.

Figure 17

Illustration of the sequential events of the NP‐loaded NP carriers comprising the prepared large‐pored mesoporous silica NP and drug‐loaded DNA‐gold NPs (AuNPs). Loading into the pores and stimulus‐responsive release of the small AuNPs in the intracellular environment were programmed by DNA hybridizations. Reproduced with permission.^{[ 135 ]} Copyright 2018, WILEY‐VCH.

Figure 18

a) Schematic illustration of DOX drug release from hairpin‐DNA‐modified NaYF4@SiO₂–Au nanoconjugates triggered by a photon 980 nm excitation. b) Changes to tumor volume following response to either of the four treatments where the three control groups indicate: only laser irradiation (control 1), without laser irradiation and treatment of nanoconjugates (control 2), and with treatment of DOX‐loaded DNA‐NPs without irradiation (Control 3). c) In vivo up‐conversion imaging of a tumor‐bearing mouse treated with the DNA_NPs. d) Pictures of the tumor bearing mice following treatment with therapy or controls. Reproduced with permission.^{[ 138 ]} Copyright 2017, WILEY‐VCH.