Multimodal Mn-doped I–III–VI quantum dots for near infrared fluorescence and magnetic resonance imaging: from synthesis to in vivo application

Abstract

The development of sensitive multimodal contrast agents is a key issue to provide better global, multi-scale images for diagnostic or therapeutic purposes. Here we present the synthesis of Zn-Cu-In-(S, Se)/Zn(1-x)Mn(x)S core-shell quantum dots (QDs) that can be used as markers for both near-infrared fluorescence imaging and magnetic resonance imaging (MRI). We first present the synthesis of Zn-Cu-In-(S, Se) cores coated with a thick ZnS shell doped with various proportions of Mn. Their emission wavelengths can be tuned over the NIR optical window suitable for deep tissue imaging. The incorporation of manganese ions (up to a few thousand ions per QD) confers them a paramagnetic character, as demonstrated by structural analysis and electron paramagnetic resonance spectroscopy. These QDs maintain their optical properties after transfer to water using ligand exchange. They exhibit T1-relaxivities up to 1400 mM(-1) [QD] s(-1) at 7 T and 300 K. We finally show that these QDs are suitable multimodal in vivo probes and demonstrate MRI and NIR fluorescence detection of regional lymph nodes in mice.

Structure and Function of Iron-Loaded Synthetic Melanin

“…35 Figure 2b shows the calculated r 1p(particle) of each SMNP. Interestingly, the plots of r 1p(particle) and r 1p(Fe(III)) show different trends ( i.e ., see Figure S5 for r 1p(particle) and r 1p(Fe(III)) results of SMNPs at 20 MHz).…”

Long-lived and Well-resolved Mn2+ Ion Emissions in CuInS-ZnS Quantum Dots

“…Meanwhile, their bandgaps can be tailored widely by growing a ZnS shell or making them be alloyed CuZnInS (CZIS) NCs with Zn, to meet the prerequisite for the well-resolved Mn 2+ d-d emission, which can be expected to be the ideal “green” materials for widespread technological applications where the Mn 2+ emission required171819. As compared to the CZIS alloyed QDs, the CIS-ZnS core-shell counterparts with the designed growth of ZnS shells, show the remarkable advantages to offer a significantly effective surface passivation for higher PL QYs192021222324, as well a more facility to control the Mn 2+ positions25. For examples, Yang et al reported the synthesis of Mn 2+ -doped CdS/ZnS core-shell NCs with Mn 2+ at controlled radial positions used a three-step synthesis route25.…”

Enhancing fluorescence in vivo imaging using inorganic nanoprobes

“…The same strategy has been used with quantum dots, mainly by incorporating Mn 2+ ions to produce bimodal MR/fluorescent probes. For example, Sitbon et al have shown that Zn-Cu-In-Se/Zn 0.9 Mn 0.1 S QDs can be used to detect regional lymph nodes in both MRI and NIR fluorescence imaging ( Figure 4) [60]. More recently, the incorporation of 64 Cu by cation exchange enables their use as PET/fluorescence contrast agents [61].…”

“…T1-weighted MRI images of a mouse before (a) and after (b) injection of QDs and the corresponding NIR fluorescence image (c). (Reproduced from ref [60]. with permission from the Royal Society of Chemistry).…”