One-Pot Green Synthesis of Fe3O4/MoS2 0D/2D Nanocomposites and Their Application in Noninvasive Point-of-Care Glucose Diagnostics

We report a novel synthesis of Fe3O4/MoS2 zero-dimensional (0D)/two-dimensional (2D) nanocomposites. When bulk MoS2 is exfoliated in the presence of thiolfunctionalized Fe3O4 nanoparticles in water, the latter anchor on the exfoliated MoS2 nanosheets because of thiol affinity toward MoS2, resulting in the Fe3O4/MoS2 nanocomposites. The one-pot reaction, room temperature processing, and use of aqueous solvents make the synthesis process facile and ecofriendly. Because of the unique 0D/2D morphology, Fe3O4/MoS2 nanocomposites show significantly higher peroxidase-like catalytic activity compared to Fe3O4 nanoparticles or MoS2 nanosheets alone. The enhanced catalytic activity has been used to detect glucose levels down to 2.4 AcM in absorbance measurements. Application toward noninvasive point-of care glucose diagnostics has been explored by developing paper-based dip and use test strips that show colorimetric response in the presence of glucose. To achieve this, Fe3O4/MoS2 nanocomposites along with other active sensing elements are printed onto paper via a desktop inkjet printer and cut into strips. When dipped into solutions of various glucose concentrations, the test strips allow colorimetric detection of glucose concentrations in a qualitative and quantitative manner. To demonstrate practical usage, we have shown that the Fe3O4/MoS2 nanocomposite-based glucose test strips are sufficient to distinguish between normal (healthy) and higher (diabetic) glucose concentrations with the naked eye. Because of the simple and ecofriendly preparation and sensing efficacy with low limit of detection, Fe3O4/MoS2 nanocomposites show promise in noninvasive point-of-care medical diagnostics.