DNA-Chitosan Hydrogels: Formation, Properties, and Functionalization with Catalytic Nanoparticles

Abstract

DNA-chitosan (DNA-CS) hydrogels were prepared on the basis of interpolyelectrolyte complexes (IPEC) in a co-assembled regime by in situ charging of the polysaccharide in a DNA solution. In contrast to poorly controlled coacervates formed upon mixing of DNA and CS solutions, stable DNA-CS IPEC hydrogels are formed at near-stoichiometric ratios of DNA and chitosan ionogenic groups. Structure, stability, and ion absorption properties of such hydrogels depended strongly on the ratio between cationic (CS) and anionic (DNA) counterparts in hydrogels. Abundant amino- and nitrogen-containing aromatic groups of co-assembled DNA and CS make their hydrogel an efficient, multitarget absorbent toward metal ions. Such strong affinity of both DNA and CS to Au3+ cation was used to entrap Au3+ ions into the DNA-CS hydrogels. Subsequent reduction of Au3+ ion inside hydrogels resulted in the formation of ∼2–3 nm size Au nanoparticles on DNA-CS scaffolds. Metallized hydrogels demonstrated catalytic activity in reduction of various nitroaromatics that depended on the ratio between CS and DNA in the hydrogel.

Adsorptive Removal of Heavy Metal Ions, Organic Dyes, and Pharmaceuticals by DNA–Chitosan Hydrogels

“…Swelling behavior as well as stability and mechanical characteristics of DNA-CS hydrogels and their dependences on a ratio of cationic and anionic components were discussed in detail elsewhere [20]. An SEM image of freeze-dried DNA-CS hydrogel (Figure 1D) shows that the hydrogel scaffold is composed of films and microfibrils (Figure 1E).…”

“…DNA-chitosan hydrogels were prepared in a similar manner as described recently [20]. In brief, dispersion of chitosan powder in 1% DNA solution was gradually acidified using glucono-D-lactone (GDL), whose hydrolysis resulted in the pH change from neutral to slightly acidic (pH 5.0) and consequent dissolution of chitosan.…”

“…Application of such waterinsoluble IPECs directly as adsorbents is limited by their poorly defined structure and non-reversible aggregative behaviour. To overcome these limitations, recently, we designed and succeeded in the preparation of interpolyelectrolyte hydrogel material from DNA and CS with a well-defined nano-and microstructure [20]. In contrast to a vast number of hybrid polymeric adsorbents that are usually prepared by a covalent cross-linking of two or more polymer components, stable DNA-CS hydrogels can be formed as a result of electrostatic interactions between oppositely charged macromolecules and require no additional cross-linking by reactive chemicals [20,21].…”

“…IPECs from natural and synthetic polyelectrolytes, including those of DNA and chitosan, have been studied intensively [18][19][20][22][23][24] and applied for the removal of environmental pollutants such as sulphates [25,26], phosphates and nitrates [27], heavy metal ions [28], bisphenol A [29], nanomaterials [30], and so on. However, the adsorption properties of IPEC hydrogels have not been fully explored and the idea of combining polyions as active adsorption components into a single hydrogel matrix has not been fully addressed in previous studies.…”

Enhanced Mechanical Properties by Ionomeric Complexation in Interpenetrating Network Hydrogels of Hydrolyzed Poly (N-vinyl Formamide) and Polyacrylamide

“…Some of these ionically crosslinked gels may have a significant degree of phase separation inside the material, or a low number of charged groups per molar mass of repeat unit, which can lead to fewer effective ionic bonds between the polymer chains [ 21 ]. Additionally, several examples of other ion complexed gels have been reported utilizing chitosan and gradually changing the pH to induce a charge in the chitosan [ 27 , 28 ].…”