Two-Photon CQDs-Based Dual-Mode Nanoprobe for Fluorescence Imaging and Magnetic Resonance Imaging of Intracellular Wide pH

Abstract

Biological fluorescence imaging technologies have attracted a lot of attention and have been widely used in biomedical fields. Compared with other technologies, fluorescence imaging has a lower cost, higher sensitivity, and easier operation. However, due to the disadvantages of one-photon (OP) fluorescence imaging, such as low spatial and poor temporal resolution and poor tissue permeability depth, the application of OP fluorescence imaging has some limitations. Though two-photon (TP) fluorescence imaging can well overcome these shortcomings of OP, the single-mode imaging remains deficient. Therefore, dual-mode imaging combined with TP imaging and magnetic resonance imaging (MRI) can make up for the deficiency well, which make dual-mode imaging for the early diagnosis of diseases more accurate. Hence, a dual-mode nanoprobe TP-CQDs@MnO2 was designed for probing the fluorescence/MR dual-mode imaging strategy of intracellular H+ by using TP-CQDs (two photon-carbon quantum dots) and MnO2 nanosheets. The MnO2 nanosheets treated as fluorescence quenching agents of TP-CQDs exhibited a supersensitive response to H+, which made the fluorescence signals turn “off” to “on” for TP fluorescence imaging, in the meantime, large amounts of Mn2+ were generated for MRI. A dual-mode nanoprobe TP-CQDs@MnO2 can monitor intracellular wide pH (4.0–8.0), and the fluorescence intensity of TP-CQDs@MnO2 has recovered up to more than six times and the corresponding results of MRI were satisfactory. TP fluorescence imaging of cells and tissues showed higher detection sensitivity and deeper tissue penetration (240.0 μm) than OP. The dual-mode imaging platform hold great promise for pH-related early diagnosis and treatment, which has great potential to improve clinical efficacy.

Superparamagnetic Iron Oxide Nanoparticles with Large Magnetic Saturation and High Particle Photon Counts for Super-Resolution Imaging of Lysosomes

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“…18 One example is the combination of MRI and optical microscopy, wherein optical microscopy is better known for visualizing the cellular structure with a high spatial resolution but lacks imaging at higher depths. 19 In contrast, MRI provides high-resolution imaging at higher depths but has limited spatial resolution. 20 One of the major drawbacks in fluorescence-decorated SPIONs is their drastic reduction of the magnetic saturation values while incorporating other materials into them.…”

Imaging strategies for monitoring the immune response

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Synthesis and Photoluminescence Mechanism of Multicolored Nitrogen-Doped Carbon Nanodots and Their Application in Polymer Self-Assemblies

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