DNA‐Based Micelles: Synthesis, Micellar Properties and Size‐Dependent Cell Permeability

Abstract

Functional nanomaterials based on molecular self-assembly hold great promise for applications in biomedicine and biotechnology. However, their efficacy could be a problem and can be improved by precisely controlling the size, structure and functions. This would require a molecular engineering design capable of producing monodispersed functional materials characterized by beneficial changes in size, shape and chemical structure. To address this challenge, we have designed and constructed a series of amphiphilic oligonucleotide molecules. In aqueous solutions, the amphiphilic oligonucleotide molecules, consisting of a hydrophilic oligonucleotide covalently linked to hydrophobic diacyllipid tails, spontaneously self-assemble into monodispersed, three dimensional micellar nanostructures with a lipid core and a DNA corona. These hierarchical architectures are results of intermolecular hydrophobic interactions. Experimental testing further showed that these types of micelles have excellent thermal stability and their size can be fine tuned by changing the length of the DNA sequence. Moreover, in the micelle system, the molecular recognition properties of DNA are intact, thus, our DNA micelles can hybridize with complimentary sequences while remain their structural integrity. Importantly, when interacting with cell membranes, the highly charged DNA micelles are able to disintegrate themselves and insert into cell membrane, completing the process of internalization by endocytosis. Interestingly, the fluorescence was found accumulated in confined regions of cytosole. Finally, we show that the kinetics of this internalization process is size-dependent. Therefore, cell permeability, combined with small sizes and natural nontoxicity, are all excellent features that make our DNA-micelles highly suitable for a variety of applications in nanobiotechnology, cell biology, and drug delivery systems.

DNA Aptamer‐Mediated Cell Targeting

“…Similar to antibodies, aptamers can specifically recognize a wide range of targets that vary from small molecules to cancer cells [8,[10][11][12] . However, they have additional properties that make Previously, our lab developed diacyl phospholipid-DNA conjugates [13] , and in this paper, we report the use of this lipid-DNA probe to modify cell surfaces for specific cell targeting. We hypothesized that aptamers would induce cellular adhesion upon spontaneous receptorligand binding in a manner that mimics the natural process of cell-cell adhesion.…”

“…Immune effector cells modified by the probe showed improved affinity, while remaining cytotoxic to target cancer cells. Our method of aptamer-mediated cell targeting is illustrated schematically in Figure 1a.To label the cell surface with aptamers, diacyl lipid-DNA aptamer conjugates were synthesized as previously described [13] . A membrane-anchored aptamer can be divided into three distinct segments ( Figure 1a).…”

“…The third segment, a synthetic diacyllipid tail with two stearic acids, is conjugated at the 5'-end as the membrane anchor. By its hydrophobic nature, the diacyllipid tail could firmly insert into the cell membrane with excellent efficiency [13] .To demonstrate lipid insertion, a fluorescent dye molecule (TAMRA) was conjugated to the 3'-end of the oligonucleotides. After incubation with cells, the labeled lipid-DNA probes were detected on the cell membrane by confocal microscopy ( Figure 1b).…”

“…Previously, our lab developed diacyl phospholipid-DNA conjugates [13] , and in this paper, we report the use of this lipid-DNA probe to modify cell surfaces for specific cell targeting. We hypothesized that aptamers would induce cellular adhesion upon spontaneous receptorligand binding in a manner that mimics the natural process of cell-cell adhesion.…”

“…To label the cell surface with aptamers, diacyl lipid-DNA aptamer conjugates were synthesized as previously described [13] . A membrane-anchored aptamer can be divided into three distinct segments ( Figure 1a).…”