DNA Supramolecular Assembly on Micro/Nanointerfaces for Bioanalysis.

Facing increasing demand for precision medicine, materials chemistry systems for bioanalysis with accurate molecular design, controllable structure, and adjustable biological activity are required. As a genetic biomacromolecule, deoxyribonucleic acid (DNA) is created via precise, efficient, and mild processes in life systems and can in turn precisely regulate life activities. From the perspective of materials chemistry, DNA possesses the characteristics of sequence programmability and can be endowed with customized functions by the rational design of sequences. In recent years, DNA has been considered to be a potential biomaterial for analysis and has been applied in the fields of bioseparation, biosensing, and detection imaging. To further improve the precision of bioanalysis, the supramolecular assembly of DNA on micro/nanointerfaces is an effective strategy to concentrate functional DNA modules, and thus the functions of DNA molecules for bioanalysis can be enriched and enhanced. Moreover, the new modes of DNA supramolecular assembly on micro/nanointerfaces enable the integration of DNA with the introduced components, breaking the restriction of limited functions of DNA materials and achieving more precise regulation and manipulation in bioanalysis. In this Account, we summarize our recent work on DNA supramolecular assembly on micro/nanointerfaces for bioanalysis from two main aspects. In the first part, we describe DNA supramolecular assembly on the interfaces of microscale living cells. The synthesis strategy of DNA is based on rolling-circle amplification (RCA), which generates ultralong DNA strands according to circular DNA templates. The templates can be designed with complementary sequences of functional modules such as aptamers, which allow DNA to specifically bind with cellular interfaces and achieve efficient cell separation. In the second part, we describe DNA supramolecular assembly on the interfaces of nanoscale particles. DNA sequences are designed with functional modules such as targeting, drug loading, and gene expression and then are assembled on interfaces of particles including upconversion nanoparticles (UCNPs), gold nanoparticles (AuNPs), and magnetic nanoparticle (MNPs). The integration of DNA with these functional particles achieves cell manipulation, targeted tumor imaging, and cellular regulation. The processes of interfacial assembly are well controlled, and the functions of the obtained bioanalytical materials can be flexibly regulated. We envision that the work on DNA supramolecular assembly on micro/nanointerfaces will be a typical paradigm for the construction of more bioanalytical materials, which we hope will facilitate the development of precision medicine.

T Lymphocyte-Captured DNA Network for Localized Immunotherapy.

The efficient isolation of immune cells with high purity and low cell damage is important for immunotherapy and remains highly challenging. We herein report a cell capture DNA network containing polyvalent multimodules for the specific isolation and in situ incubation of T lymphocytes (T-cells). Two ultralong DNA chains synthesized by an enzymatic amplification process were rationally designed to include functional multimodules as cell anchors and immune adjuvants. Mutually complementary sequences facilitated the formation of a DNA network and encapsulation of T-cells, as well as offering cutting sites of a restriction enzyme for the responsive release of T-cells and immune adjuvants. The purity of captured tumor-infiltrating T-cells reached 98%, and the viability of T-cells maintained ∼90%. The T-cells-containing DNA network was further administrated to a tumor lesion for localized immunotherapy. Our work provides a robust nanobiotechnology for efficient isolation of immune cells and other biological particles.

A DNA/Poly-(L-lysine) Hydrogel with Long Shelf-Time for 3D Cell Culture.

Deoxyribonucleic acid (DNA)-based hydrogels are emerging as promising functional materials for biomedical applications. However, the shelf-time of DNA hydrogels in biological media is severely shortened by nucleases, which limit the application of DNA hydrogels. Herein, a DNA hydrogel with long shelf-time is reported for 3D cell culture. Poly-(L-lysine) (PLL) is introduced as both a cross-linker and a protectant. The electrostatic interaction between PLL and DNA drove the formation of hydrogel. PLL coating on DNA increased the steric hindrance between DNA and nucleases, thus weakening the digestion of nucleases toward phosphodiester bond. As a result, the shelf-time of DNA/PLL hydrogel for 3D cell culture is extended from generally 1 day to longer than 15 days, which has not been achieved previously. Notably, poly-AS1411-aptamers are integrated to DNA/PLL hydrogels for anchoring U87 cells, and the cell encapsulation efficiency of the DNA/PLL hydrogels with aptamer is 4-time higher than that of the hydrogels without aptamer. DNA/PLL hydrogel provided a favorable microenvironment to support the proliferation of cells, which formed cell spheroid in 15 days. This protective coating strategy solves the long-standing problem on the shelf-time of DNA hydrogel, and is envisioned to promote the development of DNA hydrogel in more biomedical applications.