Assembly of Layered Silicate Loaded Quaternized Chitosan/Reduced Graphene Oxide Composites as Efficient Absorbents for Double-Stranded DNA

In this study, we prepared stable reduced graphene oxide (rGO) solutions with renewable resource quaternized chitosan (QCS) and layered silicate as green reducing and stabilizing agents. Rectorite (REC) and organic rectorite (OREC) are typical layered silicate employed in this work. UVvisible absorption spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy results showed the good reducing effect of QCS to produce rGO. Transmission electron microscopy, atomic force microscope, and X-ray diffraction results showed that rGO nanosheets were loaded with layered silicate through cation exchange to get a rGO/QCS/layered silicate composite. The high zeta potential (+41.4 mV) of the rGO/QCS composite showed the good stabilizing effect of QCS, and the higher zeta potential of rGO/QCS/OREC (+38.5 mV) than that of rGO/QCS/REC (+37.3 mV) indicated that OREC had a better stabilizing effect than REC. The possible assembly mechanism of the rGO/QCS/layered silicate composite was electrostatic interaction and cation exchange. The addition of the layered silicate improved the thermal stability of the composite, and rGO/QCS/OREC showed high uptake (425 mu g/mg) toward double-stranded DNA (dsDNA).