Liu Juewen, University of Waterloo, etc. "Angew": Freeze-mediated gelation, 8 hours to prepare DNA hydrogel

As a functional polymer, DNA has been widely used in various nanostructures and smart soft materials
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DNA hydrogels have been widely studied in the fields of drug delivery, controlled release and biosensing due to their good biocompatibility, programmability and stimulus responsiveness
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In order to reduce costs and introduce other functions into the hydrogel, DNA is often covalently bound to synthetic polymers such as polyacrylamide and polyisopropylacrylamide (polyNIPAm)
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The commonly used covalent binding strategy is to modify the DNA chain with amino groups and acrylamide
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The former strategy is mainly used to functionalize the pre-formed succinimide gel to attach DNA to the surface of the gel, while the latter strategy is to use copolymerization to allow high DNA loading inside (Scheme A)
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Although these modified DNAs work well, the use of unmodified DNA is preferable for cost and synthesis considerations
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Although unmodified DNA strands have been reported to be functionalized with gold nanoparticles, graphene oxide, and other materials, linking unmodified DNA to hydrogels remains to be demonstrated
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? In fact, nucleic acid bases react with hydrogel monomers
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For example, deoxyribonucleic acid can form an adduct with acrylamide by adding its nitrogen atom to the β-carbon of acrylamide (called Michael addition)
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Deoxyribonucleic acid is also susceptible to various free radicals, such as reacting with hydroxyl radicals to form adenine-hydroxy adducts
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In view of this, Liu Juewen's team at the University of Waterloo concluded that this reaction may be used to bind unmodified DNA to the hydrogel
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Reported that pentaadenine (A5) was used as the junction block, and the freezing-mediated gelation method was used to graft DNA onto the hydrogel based on acrylamide and polyNIPAm (Scheme B), achieving up to 75% in 8 hours High DNA fixation efficiency, and detection of complementary DNA (cDNA) and Hg2+
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Related work "Freezing-assisted Conjugation of Unmodified Diblock DNA to Hydrogel Nanoparticles and Monoliths for DNA and Hg2+ Sensing?" was recently published on Angewandte Chemie International Edition
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? Two synthetic strategies for DNA hydrogel? Highlights of the article 1.
Using pentaadenine (A5) as an anchor block, unmodified DNA oligonucleotides are covalently bound to hydrogel nanoparticles
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The freezing reaction conditions ensure sufficient DNA immobilization.
The DNA incorporation and hydrogel formation in this system can be completed in one step within a few hours and a binding efficiency of about 75% is obtained
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? DNA binding efficiency? 2.
The hydrogel is designed for ultra-sensitive DNA hybridization and Hg2+ detection, with detection limits of 50 pM and 10 nM, respectively, proving the feasibility of replacing acrydite-DNA with unmodified DNA
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? DNA capture? Hg2+ detection