Two-Dimensional Analysis Method for Highly Sensitive Detection of Dual MicroRNAs in Breast Cancer Cells.

Multiple biomarker detection is crucial for early clinical diagnosis, and it is significant to achieve the simultaneous detection of multiple biomarkers with the same nanomaterial. In this work, the hairpin DNA strands were selectively modified on the surface of gold nanorods (AuNRs) to construct two kinds of nanoprobes by rational design. When in the presence of dual microRNAs, AuNRs were assembled to form end-to-end (ETE) and side-by-side (SBS) dimers. Compared with a single AuNR, the dark-field scattering intensity and red color percentage variation of dimers were extremely distinguished, which could be developed for dual microRNA detection by combining the red color percentage and scattering intensity with the data processing method of principal component analysis to construct a two-dimensional analysis method. Especially, the fraction of AuNR dimers presented a linear relationship with the amount of microRNAs. Based on this, microRNA-21 and microRNA Let-7a in breast cancer cells were detected with the detection limits of 1.72 and 0.53 fM, respectively. This method not only achieved the sensitive detection of dual microRNAs in human serum but also realized the high-resolution intracellular imaging, which developed a new way for the oriented assembly of nanomaterials and biological detection in living cells.

Size-Dependent Plasmonic Resonance Scattering Characteristics of Gold Nanorods for Highly Sensitive Detection of microRNA-27a.

MicroRNAs, as one kind of significant biomarkers, play indispensable roles in the diagnosis and treatment of cancers. Yet, owing to low expression and high sequence homology, high sensitivity and specificity for microRNA detection are greatly challenging. Herein, a sensitive sensing platform with high specificity was developed for microRNA-27a (miRNA-27a) based on the miRNA-27a-triggered chemical etching of gold nanorods to a smaller size, which was accompanied by a significant blue shift and a large decrease of intensity in the localized surface plasmon resonance (LSPR) scattering and remarkable color variability from red to green. When combined with strand displacement reactions as well as liposome signal amplification and transduction, the proposed bioassay presented high selectivity toward miRNA-27a in a dynamic range from 100 fM to 3 pM and a low limit of detection of 16.5 fM (3σ/k) by dark-field microscopy. Additionally, the remarkable discrimination of single nucleotide difference suggested superior selectivity and was able to detect miRNA-27a extracted from breast cancer cells. The strategy put forward is universal, presenting amusing application prospects in the early diagnosis of various cancers by adapting the corresponding nucleotide sequences.

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

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.

Label-free gold nanorods sensor array for colorimetric detection and discrimination of biothiols in human urine samples.

Biothiols play important roles in regulating redox balance in biological systems, but their discrimination is challengeable. In this work, a colorimetric nanosensing array for biothiols was established, which was composed of gold nanorods (AuNRs) and metal ions (Hg2+, Pb2+, Cu2+, Ag+). By employing label-free AuNRs as the colorimetric probe, and the color and spectral changes of AuNRs as the output signal, principal component analysis (PCA) was applied to processing the signal and generating a clustering map. Due to the different binding affinity between biothiols and metal ions, AuNRs exhibited a unique pattern to form a fingerprint-like colorimetric array, which was able to discriminate five biothiols by the naked eyes. This strategy combines PCA and sensor array to achieve rapid and accurate discrimination and detection of biothiols. In addition, the method shows the great potential in analysis of biothiols in human urine samples.