Toward highly effective loading of DNA in hydrogels for high-density and long-term information storage

Digital information, when converted into a DNA sequence, provides dense, stable, energy-efficient, and sustainable data storage. The most stable method for encapsulating DNA has been in an inorganic matrix of silica, iron oxide, or both, but are limited by low DNA uptake and complex recovery techniques. This study investigated a rationally designed thermally responsive functionally graded (TRFG) hydrogel as a simple and cost-effective method for storing DNA. The TRFG hydrogel shows high DNA uptake, long-term protection, and reusability due to nondestructive DNA extraction. The high loading capacity was achieved by directly absorbing DNA from the solution, which is then retained because of its interaction with a hyperbranched cationic polymer loaded into a negatively charged hydrogel matrix used as a support and because of its thermoresponsive nature, which allows DNA concentration within the hydrogel through multiple swelling/deswelling cycles. We were able to achieve a high DNA data density of 7.0 × 10⁹ gigabytes per gram using a hydrogel-based system.

The Bioanalytical and Biomedical Applications of Polymer Modified Substrates

Polymers with different structures and morphology have been extensively used to construct functionalized surfaces for a wide range of applications because the physicochemical properties of polymers can be finely adjusted by their molecular weights, polydispersity and configurations, as well as the chemical structures and natures of monomers. In particular, the specific functions of polymers can be easily achieved at post-synthesis by the attachment of different kinds of active molecules such as recognition ligand, peptides, aptamers and antibodies. In this review, the recent advances in the bioanalytical and biomedical applications of polymer modified substrates were summarized with subsections on functionalization using branched polymers, polymer brushes and polymer hydrogels. The review focuses on their applications as biosensors with excellent analytical performance and/or as nonfouling surfaces with efficient antibacterial activity. Finally, we discuss the perspectives and future directions of polymer modified substrates in the development of biodevices for the diagnosis, treatment and prevention of diseases.

Single-Step Printable Hydrogel Microarray Integrating Long-Chain DNA for the Discriminative and Size-Specific Sensing of Nucleic Acids

A simple approach to fabricating hydrogel-based DNA microarrays is reported by physically entrapping the rolling circle amplification (RCA) product inside printable in situ gelling hydrazone cross-linked poly(oligoethylene glycol methacrylate) hydrogels. The hydrogel-printed RCA microarray facilitates improved RCA immobilization (>65% even after vigorous washing) and resistance to denaturation relative to RCA-only printed microarrays in addition to size-discriminative sensing of DNA probes (herein, 27 or fewer nucleotides) depending on the internal porosity of the hydrogel. Furthermore, the high number of sequence repeats in the concatemeric RCA product enables high-sensitivity detection of complementary DNA probes without the need for signal amplification, with signal/noise ratios of 10 or more achieved over a short 30 min assay time followed by minimal washing. The inherent antifouling properties of the hydrogel enable discriminative hybridization in complex biological samples, particularly for short (∼10 nt) oligonucleotides whose hybridization in other assays tends to be transient and of low affinity. The scalable manufacturability and efficient performance of these hydrogel-printed RCA microarrays thus offer potential for rapid, parallel, and inexpensive sensing of short DNA/RNA biomarkers and ligands, a critical current challenge in diagnostic and affinity screening assays.