Multifunctional hydrogels with spatially controlled light activation with photocaged oligonucleotides.

Recreating tissue environments with precise control over mechanical, biochemical, and cellular organization is essential for next-generation tissue models for drug discovery, development studies, and the replication of disease environments. However, controlling these properties at cell-scale lengths remains challenging. Here, we report the development of printing approaches that leverage polyethylene glycol diacrylate (PEGDA) hydrogels containing photocaged oligonucleotides to spatially program material characteristics with non-destructive, non-ultraviolet light. We further integrate this system with a perfusion chamber to allow us to alter the composition of PEGDA hydrogels while retaining common light-activatable photocaged DNAs. We demonstrate that the hydrogels can capture DNA functionalized materials, including cells coated with complementary oligonucleotides with spatial control using biocompatible wavelengths. Overall, these materials open pathways to orthogonal capture of any DNA functionalized materials while not changing the sequences of the DNA.

Light-Controlled Cell-Cell Assembly Using Photocaged Oligonucleotides.

The interactions between heterogeneous cell populations play important roles in dictating various cell behaviors. Cell-cell contact mediates communication through the exchange of signaling molecules, electrical coupling, and direct membrane-linked ligand-receptor interactions. In vitro culturing of multiple cell types with control over their specific arrangement is difficult, especially in three-dimensional (3D) systems. While techniques that allow one to control the arrangement of cells and direct contact between different cell types have been developed that expand upon simple co-culture methods, specific control over heterojunctions that form between cells is not easily accomplished with current methods, such as 3D cell-printing. In this article, DNA-mediated cell interactions are combined with cell-compatible photolithographic approaches to control cell assembly. Specifically, cells are coated with oligonucleotides containing DNA nucleobases that are protected with photocleavable moieties; this coating facilitated light-controlled cell assembly when these cells were mixed with cells coated with complementary oligonucleotides. By combining this technology with digital micromirror devices mounted on a microscope, selective activation of specific cell populations for interactions with other cells was achieved. Importantly, this technique is rapid and uses non-UV light sources. Taken together, this technique opens new pathways for on-demand programming of complex cell structures.

Nanoparticle targeting of mechanically modulated glycocalyx.

The mechanical properties and forces in the extracellular environment surrounding alveolar epithelial cells have the potential to modulate their behavior. Particularly, breathing applies 3-dimensional cyclic stretches to the cells, while the stiffness of the interstitium changes in disease states, such as fibrosis and cancer. A platform was developed that effectively imitates the active forces in the alveolus, while allowing one to control the interstitium matrix stiffnesses to mimic fibrotic lung tumor microenvironments. Alveolar epithelial cancer cells were cultured on these platforms and changes in the glycocalyx expression were evaluated. A complex combination of stiffness and dynamic forces altered heparan sulfate and chondroitin sulfate proteoglycan expressions. Consequently, we designed liposomal nanoparticles (LNPs) modified with peptides that can target heparan sulphate and chondroitin sulfates of cell surface glycocalyx. Cellular uptake of these modified nanoparticles increased in stiffer conditions depending on the stretch state. Namely, chondroitin sulfate A targeting improved uptake efficiency in cells experiencing dynamic stretches, while cells seeded on static stiff interstitium preferentially took up heparan sulfate targeting LNPs. These results demonstrate the critical role that mechanical stiffness and stretching play in the alveolus and the importance of including these properties in nanotherapeutic design for cancer treatment.