Bulk pH-Responsive DNA Quadruplex Hydrogels Prepared by Liquid-Phase, Large-Scale DNA Synthesis

Abstract

A new pH-responsive hydrogel biomaterial, that is composed of solely two popular biocompatible materials, oligodeoxynucleotides (ODN) and polyethylene glycol (PEG) have been prepared. Merely five deoxycytidine residues were elongated to the ends of linear or 4-arm PEG in ×1000 larger scale than conventional systems by using liquid-phase DNA synthesis technique, and applied them as a macromonomer for the preparation of hydrogels. The syntheses of the conjugates are simply elongating ODN onto the ends of PEG as a semisolid phase substrate using standard phosphoramidite chemistry. The resulting dC5-PEG conjugates gave quite stable and stiff hydrogels triggered by the formation of a unique DNA quadruplex, i-motif. Introduction of only one chemical linkage between two linear conjugates resulted in unexpectedly high thermal stabilities for the melting temperatures of i-motifs themselves. Nonlinearly improved rheological properties compared to the original linear conjugates were also observed, probably because of topological entanglement between macromonomers of fused circles.

A Versatile Crosslinking Strategy on Facile Fabrication of Fluorescent Hydrogels via o‐Phthalaldehyde Ternary Condensation

“…As shown in Figures 2E and 2F, the OSN gel with Tetra PEG of 20 kDa showed outstanding compressive strength (1.7 MPa) and compressive modulus (30 kPa). The mechanical properties of OSN gels were superior to those of recently reported Tetra PEG hydrogels under the same solid content, [ 25‐27 ] probably due to the high chemical reactivity of the OPA for the ternary condensation.…”

Smart Nucleic Acid Hydrogels with High Stimuli-Responsiveness in Biomedical Fields

“…Since then, the era of co-synthesis of NAHs by polymers and FNAs has been entered. In recent years, polymers and nanomaterials have started to be used to prepare NAHs with nucleic acids, including, but not limited to, graphene oxide graphene oxide (GO) [15][16][17], carbon dots (CD) [18][19][20], carbon nanotubes [21], quantum dots [22], magnetic beads [23], polyacrylamide (PAM) [24][25][26][27][28][29][30], poly-N-isopropylacrylamide (p-NIPAM) [31,32], polyethylene glycol (PEG) [33][34][35][36], and poly-L-lysine (PLL) [37]. The use of these materials helps to improve the performance of hydrogels, reduce nucleic acid use, and speed up the synthesis of hydrogels.…”

Putting DNA to Work as Generic Polymeric Materials

“…Kuzuya and colleagues synthesized oligo(dG)‐modified four‐arm polyethylene glycol (PEG), which was stabilized by monovalent cations to form G‐quadruplexes which served as crosslinkers for the hydrogels [39] . By the same method, they also prepared oligo(dC)‐modified four‐arm PEG to create hydrogels crosslinked by proton‐induced i‐motif structures [40] . The Walther group developed a one‐pot liquid‐phase oligonucleotide synthesis to prepare two different four‐arm PEGs for producing the hydrogels [41] …”