Size‐Dependent Optical Absorption of Layered MoS₂ and DNA Oligonucleotides Induced Dispersion Behavior for Label‐Free Detection of Single‐Nucleotide Polymorphism

Abstract

Size‐dependent optical absorption of semiconductive (2H) layered molybdenum disulfide (MoS2), exhibiting great discrimination abilities to single‐ and double‐stranded DNA (ssDNA) and (dsDNA), is studied. In the presence of high concentration of salt, layered MoS2 trends to aggregate rapidly, leading to the increases of sizes in both vertical and lateral dimensions of the nanosheets, which results from the interplay between van der Waals attraction and electrical double‐layer repulsion. Meanwhile, the aggregation behavior of layered MoS2 is remarkably inhibited by the synergistic effects of DNA oligonucleotides. ssDNA can adsorb on the surface of layered MoS2, resulting in a great dispersion, even in the presence of high concentration of salt, while the dispersion behavior is weakened when ssDNA is replaced by dsDNA. Whereas compared to graphene with zero bandgap energy, layered MoS2, with semiconductive properties, exhibits great characteristic optical absorption in visible wavelength region devoted to exploring the aggregation behavior of layered MoS2. Therefore, DNA oligonucleotides induced size control of layered MoS2, contributing to the regular change of its characteristic absorption in visible region, is considered a label‐free bioassay for the detection of single‐nucleotide polymorphism. Due to its easy operation and high specificity, it is expected that the proposed assay holds great promise for further applications.

Comparison of MoS2, WS2, and Graphene Oxide for DNA Adsorption and Sensing

“…30 Thiolated DNA was also attached to AuNPs to improve sensing based the intrinsic photoluminescence property of MoS2. 31 Adsorption of DNA improves the colloidal stability of MoS2 nanosheets, 32 and DNA can even exfoliate WS2, 33 suggesting a strong interaction.…”

Layered Aggregation with Steric Effect: Morphology‐Homogeneous Semiconductor MoS2 as an Alternative 2D Probe for Visual Immunoassay

“…Bulk MoS 2 is a semiconductor with an indirect bandgap of 1.3 eV, while single‐, double‐, and triple‐layer MoS 2 are direct‐gap semiconductors with bandgaps of 1.9, 1.65, and 1.35 eV, respectively. The thicknesses of TMDs determine their bandgaps, and strong optical absorption is observed from their aqueous dispersion . From absorption spectra of MoS 2 samples, four absorption peaks located at 600–700 and 400–500 nm zones were observed, which were coincided with the general features of semiconducting 2H polytypes (Figure d).…”

“…Sonication was then adopted for their exfoliation. Herein, ultrasonic waves made cavitation bubbles that contributed to high‐energy jets, breaking up bulk crystallites (Figure S1, Supporting Information) . MoS 2 crystals were vertically exfoliated to from thin nanosheets, which were stably dispersed in surfactant solution.…”

“…Semiconducting layered MoS 2 , as a type example from 2D family of TMDs, possesses characteristic optical absorption in visual zone. This characteristic made 2D MoS 2 own potential to be generally visual probes for sensors . Nevertheless, up to now, inhomogeneous sizes of 2D MoS 2 in both vertical and lateral dimension remarkably impeded its practical application .…”

Highly sensitive protein detection via covalently linked aptamer to MoS₂ and exonuclease-assisted amplification strategy

“…DNA, protein, and metal ions have been detected by using simple DNA absorption on the surface of MoS 2 . [3][4][5] However, the physisorption of fluorescently labeled DNA was susceptible to nonspecific probe displacement and the false-positive signals. 6 MoS 2 can stabilize metal nanoparticles and form composites which extend its functionalities as a novel catalytic, magnetic, and optoelectronic nanomaterial.…”