Intelligent, Biodegradable, and Self‐Healing Hydrogels Utilizing DNA Quadruplexes

Abstract

A new class of hydrogels utilizing DNA (DNA quadruplex gel) has been constructed by directly and symmetrically coupling deoxynucleotide phosphoramidite monomers to the ends of polyethylene glycols (PEGs) in liquid phase, and using the resulting DNA‐PEG‐DNA triblock copolymers as macromonomers. Elongation of merely four deoxyguanosine residues on PEG, which produces typically ≈10 grams of desired DNA‐PEG conjugates in one synthesis, resulted in intelligent and biodegradable hydrogels utilizing DNA quadruplex formation, which are responsive to various input signals such as Na+, K+, and complementary DNA strand. Gelation of DNA quadruplex gels takes place within a few seconds upon the addition of a trigger, enabling free formation just like Ca+‐alginate hydrogels or possible application as an injectable polymer (IP) gel. The obtained hydrogels show good thermal stability and rheological properties, and even display self‐healing ability.

Scalable One-Pot-Liquid-Phase Oligonucleotide Synthesis for Model Network Hydrogels

“…The capping step is often omitted in LPOS due to the high coupling efficiencies achieved compared to heterogeneous SPOS, and in order to simplify the procedure. [51][52][53]68 Merging all three steps -coupling, oxidation, deprotection/detritylation -into a one-pot process with a single precipitation workup is the key to making large-scale PEG-DNA building block production feasible. The realization of this one-pot procedure requires to solve the following steps:…”

“…Tanaka et al prepared 4-arm PEG-DNA building blocks with few nucleotides to form hydrogels via non-duplex interaction, such as G-quadruplex and C-based imotifs. [52][53] Critically, these gelation principles only require short DNA sequences, and the presently available short length of a few nucleotides does indeed not allow for linking via DNA duplex hybridization in a suitable temperature regime. Thus, they do not provide access to exploiting the programmable molecular recognition known from DNA.…”

Application of DNA Quadruplex Hydrogels Prepared from Polyethylene Glycol-Oligodeoxynucleotide Conjugates to Cell Culture Media

“…We chose L4.6k-dG4 [25], in which four dG residues were coupled to both of the ends of linear PEG4.6k with modified HELP synthesis (Figure 1b), as the macromonomer to prepare G-quadruplex hydrogels. When equal volume of 2×Eagle′s minimal essential medium (E-MEM) was added to 30 wt % L4.6k-dG4 stock solution, quite stiff hydrogel, which was still stable even at 37 °C, was obtained (Figure 2a).…”

“…Not only regular duplexes [4], but also four-stranded structures called “G-quadruplex” and “i-motif” are often used to construct DNA hydrogels due to their attractive features: metal ion or pH responsiveness [14,15,16,17,18,19,20,21,22,23,24]. We have recently developed a new class of hydrogels utilizing such DNA quadruplexes as cross-linking points of the 3D polymer network [25,26,27]. Polyethylene glycol-oligodeoxynucleotide (PEG-ODN) conjugates bearing merely four deoxyguanosine residues (dG4) for G-quadruplexes or five deoxycytidine residues (dC5) for i-motifs at the ends of linear or four-way branched PEG, were prepared as macromonomers by applying high-efficiency liquid phase (HELP) synthesis of oligonucleotides developed by Bonora et al with a few modifications [28].…”

Hydrogels Utilizing G-Quadruplexes

“…25 A versatile hydrogel system consists of only two popular biocompatible materials; DNA and polyethylene glycol (PEG) were prepared by applying HighEfficiency Liquid Phase (HELP) synthesis of oligonucleotide, 26 to overcome the scale barrier of automated solid-phase DNA syntheses. DNA-PEG-DNA triblock conjugates, in which merely four or five consecutive nucleotides are symmetrically introduced, prepared at least in gram scale with HELP, realized intelligent and biodegradable hydrogels.…”