Synthesis of Ultrathin MnS Shell on ZnS: Mn Nanorods by One‐Step Coating and Doping for MRI and Fluorescent Imaging

Abstract

advantages of fl uorescence and MRI imaging, have attracted a great deal of attention in particular. [15][16][17] Semiconductor nanocrystals (or quantum dots) have also been of quite some interest over recent decades because of their unique optical properties and extensive applications. Compared to other inorganic fl uorescent materials, such as carbon dots, rare-earth upconversion nanocrystals, and noble-metal clusters, semiconductor nanocrystals have unique fl uorescent advantages, such as high quantum yields (QYs), long lifetime, and minimal self-absorption. [ 18,19 ] However, these semiconductor nanocrystals are not suited to widespread applications in bioimaging and cell labeling in vivo due to their high toxicity related to the intrinsic Cd (such as CdS and CdSe).Mn 2+ -doped semiconductor nanocrystal (NC) emitters have been extensively researched owing to their low toxicity and yellow emission at 570-580 nm, originating from the 4 T 1 -6 A 1 transition of the Mn 2+ on the Zn 2+ sites. [20][21][22][23][24] These properties refl ect the potential use of Mn-doped NCs as fl uorescence imaging agents. Schneider et al., for example, successfully prepared thioglycerol-capped Mn-doped ZnS quantum dots as a two-photon fl uorescent nanoprobe for fl uorescence imaging applications. [ 25 ] Wu et al. synthesized probes based on Mn-doped ZnS quantum dots to distinguish between oxidoreductase isozyme NQO1 expressing and non-expressing cancer cell lines. [ 26 ] Mn-doped ZnS quantum dots synthesized by Wu's team, when used as a new imaging moiety for eccrine latent fi ngerprints, revealed the material's potential applications in forensic science. [ 27 ] Fluorescent quantum dots of Mndoped ZnS, synthesized by Manzoor et al., also showed a high selectivity in targeted cancer imaging. [ 28 ] Because of its fi ve unpaired electrons, Mn 2+ can also produce an effi cient positive contrast enhancement as an alternative MRI contrast agent. [ 29,30 ] Compared to the commonly used Gd 3+ , Mn 2+ not only has a lower toxicity, but is also present as a trace element in ionic form in the human body. [ 31,32 ] The intrinsic properties of Mn include a high spin number, long electronic relaxation time, and good exchange with water, thus increasing the signal intensity of MRI T 1 images. At the biochemical level, Mn is involved in the mitochondrial functionthe greater the mitochondrial density in the cell, the higher the Multifunctional nanoprobes for bioimaging have attracted considerable interest in terms of their potential applications in clinical medicine and diagnosis. This article reports the fabrication of a new bifunctional nanoprobe, consisting of an ultrathin MnS shell coating on ZnS:Mn nanorods (NRs), for bioimaging in combination with fl uorescence and magnetic resonance imaging (MRI) techniques. The prepared ZnS:Mn/MnS core-shell NRs show an orange emission at 587 nm in wavelength, suggesting they are well suited for fl uorescent bio-imaging due to their large Stokes shift.After surface modifi cation, the obtained core-shell NR...

Bifunctional Pyrrolidin-2-one Terminated Manganese Oxide Nanoparticles for Combined Magnetic Resonance and Fluorescence Imaging

“…In some examples, MRI activity of the MnO/dye NPs was noted, but no quantitative relaxivity values were supplied . High r 1 relaxivity, however, was shown by ultrathin fluorescent MnS-capped ZnS/Mn nanorods ( r 1 = 9.3 mM –1 s –1 ), albeit at a low magnetic field of 0.47 T . A fluorescent dye, Cy7.5, was conjugated through a poly­(ethylene glycol) linker to Mn 3 O 4 NPs by Chen and colleagues, but these NPs showed low r 1 values (∼0.5 mM –1 s –1 ) at 7 T, possibly owing to the presence of higher oxidation states of Mn .…”

“…23 In another example of Mn-based bifunctional CAs, the synthesis of protoporphyrin IX conjugated MnO NPs required over three separate conjugation steps to attach the porphyrin moiety to the surface of MnO NPs. 24 Other examples of this class of bifunctional nanoparticulate contrast agents include Gd-doped MnCO 3 NPs, 28 MnS-coated Mn-doped ZnS nanorods, 29 and Cy 7.5 conjugated PEGylated Mn 3 O 4 NPs. 30 In this report, we show that biocompatible, water-dispersible pyrrolidin-2-one-capped NPs (MnO pyrr ) endowed with MRI and fluorescence imaging capabilities can be prepared without postsynthetic ligand exchange or functionalization of the NP surface (see Figure 1).…”

“…In another example of Mn-based bifunctional CAs, the synthesis of protoporphyrin IX conjugated MnO NPs required over three separate conjugation steps to attach the porphyrin moiety to the surface of MnO NPs . Other examples of this class of bifunctional nanoparticulate contrast agents include Gd-doped MnCO 3 NPs, MnS-coated Mn-doped ZnS nanorods, and Cy 7.5 conjugated PEGylated Mn 3 O 4 NPs …”

Non-invasive Diagnosis and Postoperative Evaluation of Carotid Artery Stenosis by BSA-Gd2O3 Nanoparticles-Based Magnetic Resonance Angiography

“…This feature is not conducive to high-resolution imaging, as it necessitates a significant amount of time and repeated injections from diagnosis to treatment . To date, great efforts have been devoted to design and fabricate novel long-circulation MR contrast agents, such as Gd-based contrast agents (Gd 2 O 3 , NaGdF 4 , , Gd-liposomes, , Gd-polymer, and Gd-dendrimer), Fe-based contrast agents (Fe 3 O 4 , Fe 2 O 3 , Fe 5 C 2 , and FeS), and Mn-based contrast agents (MnO, MnO 2 , , MnS, MnCO 3 , and Mn 3 (PO 4 ) 2 ). Despite remarkable advancements, many MRA contrast agents suffer from harsh synthesis conditions, tedious synthesis processes, and the risk of toxicity derived from harmful substances.…”

Nanoscale Metal–Organic Frameworks Decorated with Graphene Oxide for Magnetic Resonance Imaging Guided Photothermal Therapy

“…[1] Presently,m agnetic resonancei maging (MRI) is one of the most widely used and powerful noninvasive techniques in diagnosis and post-therapy evaluation of cancer. [2][3][4][5][6] With distinct imagingc haracterizations, MRI offers high spatialr esolution and deep tissue penetration. [7] On the other hand, current cancert reatments mainly employ radio-and chemotherapy, which destroyn ormal cells and healthyt issue duringt reatment, and eventually the immunity of patients.…”