Preparation and characterization of DNA/allophane composite hydrogels

•The interaction between phosphate groups of DNA and Al-OH groups.•The DNA molecules are wrapped around the allophane clusters.•The thermal denaturation of DNA duplex is restricted in DNA/AK70 hydrogels. The preparation and characterization of the composite hydrogels based on double-stranded deoxyribonucleic acid (DNA) and natural allophane (AK70) were reported. To understand the propensity of the natural allophane to adsorb the DNA molecules, using zeta potential measurement, Fourier transform infrared spectroscopy (FTIR) and electrophoresis analyses assessed the adsorption characteristics. The freeze-dried DNA/AK70 hydrogels were demonstrated that the DNA bundle structure with a width of ∼2μm and a length of ∼15–20μm was wrapped around the clustered allophane particles as revealed by FE-SEM/EDX analysis. The incorporation of AK70 in hydrogels induced the increase in the enthalpy of the helix-coil transition of DNA duplex due to the restricted molecular motions of the DNA duplex facilitated by the interaction between the phosphate groups of DNA and the protonated +(OH2)Al(OH2) groups on the wall perforations of the allophane.