MicroRNA exhibits differential expression levels in cancer and can affect cellular transformation, carcinogenesis and metastasis. Although fluorescence techniques using dye molecule labels have been studied, label-free molecular-level quantification of miRNA is extremely challenging. We developed a surface plasmon resonance sensor based on two-dimensional nanomaterial of antimonene for the specific label-free detection of clinically relevant biomarkers such as miRNA-21 and miRNA-155. First-principles energetic calculations reveal that antimonene has substantially stronger interaction with ssDNA than the graphene that has been previously used in DNA molecule sensing, due to thanking for more delocalized 5s/5p orbitals in antimonene. The detection limit can reach 10 aM, which is 2.3–10,000 times higher than those of existing miRNA sensors. The combination of not-attempted-before exotic sensing material and SPR architecture represents an approach to unlocking the ultrasensitive detection of miRNA and DNA and provides a promising avenue for the early diagnosis, staging, and monitoring of cancer.

In this work, a high performance vertical-type photodetector based on two-dimensional (2D) CH ₃ NH ₃ PbI ₃ perovskite nanosheets was fabricated. The low trap density of the perovskite nanosheets and their short carrier diffusion distance result in a significant performance enhancement of the perovskite-based photodetector. The photoresponsivity of this vertical-type photodetector is as high as 36 mA W ⁻¹ at visible wavelength, which is much better than traditional perovskite photodetectors (0.34 mA W ⁻¹ ). Compared with traditional planar-type perovskite-based photodetectors, this vertical-type photodetector also shows the advantages of low-voltage operation and large responsivity. These results may pave the way for exploiting high performance perovskite-based photodetectors with an ingenious device design.

We used scattering-type scanning near-field optical microscopy (s-SNOM) to investigate the plasmonic properties of edges in well-defined graphene nanostructures, including sharp tapers, nanoribbons and nanogaps, which were all fabricated via the growth-etching chemical vapor deposition (GECVD) method. The obtained near-field images revealed the localized plasmon modes along the graphene nanoribbon; these modes strongly depended on the size of the graphene pattern, the angle of the tapered graphene and the infrared excitation wavelength. These interesting plasmon modes were verified by numerical simulations and explained by the reflection, and interference of electromagnetic waves at the graphene–SiO₂ edge. The constructive interference at the graphene nanogap caused by charge accumulation was demonstrated for the first time. Using the infrared nanoimaging technique, greater plasmon broadening was observed in the zigzag edge than in the armchair edge. Our study suggests that graphene edges should be separated by an effective working distance to avoid the overlapping of localized plasmon modes, which is very important for the design of graphene-based plasmonic circuits and devices.