In this study, we constructed a SERS assay platform that can be used for the ultrasensitive detection of cerebral infarction (CI)-associated miR-106a-5p based on the recognition competition strategy and the highly efficient catalytic activity of Au@Pt NRs nanoenzymes. When the target miR-106a-5p is present in the detection solution, it binds to the nucleic acid aptamer (cDNA), leading to the detachment of its complementary strand (H1) carrying Au@Pt NRs from the surface of AuNHs, and the oxidation of TMB is reduced, resulting in the decrease of SERS signal. In addition, this method enables single-step, ultrasensitive detection of target miRNAs in patient serum with a limit of detection (LOD) of 0.96 fM, which is consistent with the results of real-time quantitative polymerase chain reaction (qRT-PCR) and fluorescence. This method provides a novel approach for the effective detection of miRNAs, which is of great clinical value for the early detection of CI.
Purpose Pt-based nanostructures are one of the promising nanomaterials for being used in catalysts, sensors, and therapeutics. However, their impacts on the health and biological systems are not adequately understood yet. Methods In this work, nanorods composed of ultrasmall platinum (Pt) nanoparticles deposited on the surface and gold nanorod as the core (Au@Pt NRs) were synthesized, and the distribution and toxic effects of Au@Pt NRs were investigated in C57BL/6 mice with intravenous injection by using atomic absorption spectroscopy (AAS), transmission electron microscope (TEM), hematoxylin-eosin (HE) staining and blood cell analyzer. Results At the time point of Day 1, Day 8 and Day 16 post injection of Au@Pt NRs (6 mg/kg of Pt atom), Au@Pt NRs were mainly accumulated in the liver and spleen. The energy dispersive spectrometer mapping images showed Au@Pt NRs experienced quick corrosion and Au released faster than Pt in the physiological environments. The catalase (CAT) activity in tissues increased slightly in the early stage of the Au@Pt NRs exposure and went down to the normal level. With HE staining, inflammatory cells infiltration could be seen in the tissues, while no significant influences were detected on the blood biochemistry and the function of liver and kidney. Conclusion In conclusion, intravenously injected Au@Pt NRs mainly distributed in the liver and spleen with comparable levels, and did not exert any significant toxic effects on the organs’ function within two weeks; meanwhile, Au@Pt NRs were able to degrade, which indicated acceptable safety to the mice and potentials of biomedical application.
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