Amino-modified graphene oxide nanoplatelets for photo-thermal and anti-bacterial capability

In this study, graphene oxide (GO) nanoplatelets have been successfully amino-functionalized by electrostatic absorbed process of poly(diallyldimethylammoniumchloride) (GO-PDDA) and hydrothermal of ammonia solution (AMGO). The characterizations of GO derivative nanoplatelets (GO, GO-PDDA and AMGO nanoplatelets) were evaluated by Raman, X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and zeta potential. The results show that the zeta potential change is from -51.7 mV (GO) to 29.7 mV (GO-PDDA) and 33.2 mV (AMGO), indicated that the huge charge changing by the amino group modification. A model bacterium, Escherichia coli (E. coli), was used to evaluate the anti-bacterial activity of GO, GO-PDDA and AMGO nanoplatelets. The anti-bacterial activity of AMGO and GO-PDDA nanoplatelets is superior to pristine GO nanoplatelets, owing to the positive charge of amino-modification to capture the negative charge of bacteria cell walls. Especially in AMGO nanoplatelets, it displays the most powerful anti-bacterial capability, due to the higher grafting density of amino functional group (higher zeta potential of AMGO). Furthermore, the photo-thermal test exhibits the temperature of GO derivative nanoplatelets could increase 38-50 degrees C while exposed in the near-IR laser (808 nm) for 5 min. Combination of physical capturing/splintering and photo-thermal effects for the bacteria, we suggest that amino-functionalized GO nanoplatelets would be anticipated to apply in the anti-bacterial coating and photo-thermal therapy.