Ratiometric immunoassays built from synergistic photonic absorption of size-diverse semiconducting MoS2 nanostructures

Abstract

The intrinsic photonic properties of liquid-exfoliated (LE) MoS₂ struggle extremely for the desired optical applications. Theoretical and experimental results briefly reveal that the broadband photonic absorption in LE MoS₂ samples is ascribed to a synergistic mechanism, originated from layer-modulated electronic bandgaps and quantum confinement effects of ultra-small nanodots. Size fractionation of LE MoS₂ is promoted with differential centrifugation, and narrowed size distributions of fractionated samples are identified. Tunable aggregation of LE MoS₂ alters the distributions of the vertical and lateral dimensions, exhibiting ratiometric changes on photonic performances. With the integration of immunoassays, semiconducting MoS₂ nano-probes with antibody modifications can linearly respond to specific targets, e.g. carcino-embryonic antigens, ranging from 5.0 to 180.0 ng mL⁻¹, via ratiometric photonic absorption measurements. The nanostructured MoS₂ optical ratiometric strategy exhibits a high repeatability, simple operation, low cost, and label-free characteristics, offering an alternative platform for practical immunoassays.