Spherical Nucleic Acid Probe Based on 2′-Fluorinated DNA Functionalization for High-Fidelity Intracellular Sensing

Abstract

Traditional spherical nucleic acids (SNAs) based on gold nanoparticles (AuNPs) assembled through Au−S covalent bonds are widely used in DNA-programmable assembly, biosensing, imaging, and therapeutics. However, biological thiols and other chemical substances can break the Au−S bonds and cause response distortion during the application process, specifically in cell environments. Herein, we report a new type of SNAs based on 2′-fluorinated DNA-functionalized AuNPs with excellent colloidal stability under high salt conditions (up to 1 M NaCl) and over a broad pH range (1−14), as well as resistance to biothiols. The fluorinated spherical nucleic acid probe (Au/FDNA probe) could detect targeted cancer cells with high fidelity. Compared to the traditional thiolated DNA-functionalized AuNP probe (Au−SDNA probe), the Au/FDNA probe exhibited a higher sensitivity to the target and a lower signal-to-background ratio. Furthermore, the Au/FDNA probe could discriminate target cancer cells in a mixed culture system. Using the proposed FDNA functionalization method, previously developed SNAs based on AuNPs could be directly adapted, which might open a new avenue for the design and application of SNAs.S pherical nucleic acids (SNAs) based on gold nanoparticles (AuNPs) were first prepared by Chad A. Mirkin and colleagues in 1996, 1 which attracted worldwide interest and opened a new path for the field of bio-nanotechnology. 2−4 These nanomaterials are composed of ultradense nucleic acids with an AuNP core, retaining the recognition functions and programmability of nucleic acid molecules combined with the unique optical, chemical, electrical, and catalytic properties of AuNPs to impart the SNAs with desirable chemical−physical properties and biological functions. 5 Following this, SNAs were widely used in the fields of DNA-programmable assembly, biological analysis, molecular imaging, gene therapeutics, diagnostics, and drug delivery. 6−12 Notably, the thiolated oligonucleotide functionalization of AuNPs prepared through the formation of Au−S bonds has been widely investigated. However, under physiological conditions, the Au−S bond is easily affected by biological thiols, for example, glutathione (GSH) and sulfhydryl ligands, resulting in false-positive signals. 13,14 Therefore, novel SNA alternatives with potentiated stability are urgently needed.In order to avoid the high concentrations of biothiols in living cells, FRET nanoflares were constructed to build a ratiometric fluorescent measurement method that calibrates for nonspecific false-positive signals due to the fracture of the Au− S bond. 14 However, this method fails to address the breakage of Au−S bonds by biothiols. In addition, a selenol-functionalized AuNP probe based on the Au−Se bond has been

Carrier-Free Nanovaccine: An Innovative Strategy for Ultrahigh Melanoma Neoantigen Loading

“…These results suggested that the interactions between CpG and Obsl1 were weaker and insufficient to form stable nanostructures; thus, the fluorine substitution in CpG might play a key role in constructing stable 2′F-CpG/Obsl1 NPs for vaccine applications. Fluorine atoms exhibit the highest electronegativity and can influence the physicochemical and electronic properties of other molecules via dispersion forces and dipole effects. − Therefore, MD simulations were performed to study the interactions between 2′F-CpG and Obsl1. The molecular docking model of 2′F-CpG and Obsl1 indicated that the introduction of a fluorine atom into CpG enhanced the adsorption capacity of 2′F-CpG to amino acid residues (Figure c,d and Video S1), which was confirmed by MD (Figure e,f).…”

Improved Catalytic Activity of Spherical Nucleic Acid Enzymes by Hybridization Chain Reaction and Its Application for Sensitive Analysis of Aflatoxin B1

“…Spherical nucleic acids enzymes (SNAzymes) are usually fabricated using functional DNA strands decorated on gold nanoparticles (AuNPs), which are extensively applied in biosensing depending on their ease of synthesis, programmable functionalization, and high stability [1][2][3][4][5]. Compared to other DNA sequences, G-quadruplex (G4) exhibits higher density of the nucleic acid layer after it is modified on the surface of AuNPs through the Au-S covalent band [6], showing good peroxidase-mimicking activity with the presence of the cofactor hemin [7][8][9][10].…”