High-Resolution Vertical Polarization Excited Dark-Field Microscopic Imaging of Anisotropic Gold Nanorods for the Sensitive Detection and Spatial Imaging of Intracellular microRNA-21

Abstract

As an important biomarker for early diagnosis of cancers, sensitive detection and high-resolution imaging of microRNA-21 in cancer cells have become important and challengeable. In this work, highly sensitive detection and spatial imaging of intracellular microRNA-21 were realized by the reduced signal background through vertical polarization excitation with a polarizer. The lateral local surface plasmon resonance property of gold nanorods (AuNRs) displayed a pronounced green color with low scattering intensity, which was adjusted to red color with strong scattering intensity when the core–satellite gold nanoparticle (AuNP) assembly was constructed on the side of AuNRs through a catalyzed hairpin assembly (CHA) circuit in the presence of microRNA-21. This unique approach allows for effectively reducing the strong background signal to improve the sensitivity of detection. Additionally, the proposed strategy can not only realize the sensitive detection of microRNA-21 with the limit of detection as low as 2 pM (3σ) but also achieve the high spatial imaging of cancer cells, which provided a specific strategy for the construction and imaging of intracellular imaging probes. It is believed that the simple and sensitive approach on the basis of lateral local surface plasmon resonance property of anisotropic AuNRs with excellent sensitivity combined with high spatial imaging holds promising potentials to visualize intracellular microRNAs with low abundance.

Dark-Field Microscopy: Recent Advances in Accurate Analysis and Emerging Applications

“…Wang et al also selected gold nanorods emitting more sensitive vertical polarization to develop a vertical polarization excited DFM. Intracellular microRNA-21 could be detected and spatially imaged with a high resolution, and this technology was also able to distinguish the probe and the background (Figure B) …”

A Homogeneous Multicomponent Nucleic Acid Enzyme Assay for Universal Nucleic Acid Detection by Single-Particle Inductively Coupled Plasma Mass Spectrometry

“…It can prevent these differences from being submerged in the overall signal of nanoparticles in solution, thereby improving the sensitivity of nanoparticle-based homogeneous assays. Currently developed single-particle counting techniques for homogeneous assays are mainly based on fluorescence microscopy, , dark-field microscopy, , diffraction spectroscopy, fluorescence cross correlation spectroscopy, resistive-pulse sensors, optomagnetic sensors, and inductively coupled plasma mass spectrometry (ICP-MS). − Among them, most of the optical techniques like fluorescence microscopy and dark-field microscopy rely on manual counting, which is labor-/time-intensive and imprecise, and others like resistive-pulse sensors may suffer from matrix interference. By contrast, single-particle (SP)-ICP-MS is a sensitive, accurate, automated, and matrix-resistant technique for detecting nanoparticles, in which the pulse frequency is proportional to the particle concentration of nanoparticles and the pulse intensity reflects the size of corresponding nanoparticle.…”

Dual Imaging of Poly(ADP-ribose) Polymerase-1 and Endogenous H2O2 for the Diagnosis of Cancer Cells Using Silver-Coated Gold Nanorods

“…Recently, single-particle plasmonic imaging via dark-field microscope (DFM) has received wide applications in biochemical detection and cellular imaging. − It displays superiorities over other averaged measurement strategies such as low background interference, improved spatiotemporal resolution, and extremely small consumption. , Based on the dark-field imaging technique, a considerable number of noble metal nanoparticles have been employed as scattering probes. − Among them, gold nanorods (AuNRs) present strong localized surface plasmon resonance (LSPR) performance, which depends strongly on their size, morphology, and surrounding environment. − …”