Dual-Modality Imaging Probes with High Magnetic Relaxivity and Near-Infrared Fluorescence Based Highly Aminated Mesoporous Silica Nanoparticles

Zhu Fei-Peng,Lu Guang-Ming,Wang Chun-Yan,Tian Ying,Wang Shou-Ju,Wang Jian-Dong,Sun Jing,Chen Guo-Tao,Wang Xin,Tang Yu-Xia,Teng Zhao-Gang,Liu Ying

doi:10.1155/2016/6502127

Abstract

Dual-modal imaging by combining magnetic resonance (MR) and near-infrared (NIR) fluorescence can integrate the advantages of high-resolution anatomical imaging with high sensitivity in vivo fluorescent imaging, which is expected to play a significant role in biomedical researches. Here we report a dual-modality imaging probe (NIR/MR-MSNs) fabricated by conjugating NIR fluorescent heptamethine dyes (IR-808) and MR contrast agents (Gd-DTPA) within highly aminated mesoporous silica nanoparticles (MSNs-NH2). The dual-modality imaging probes NIR/MR-MSNs possess a size of ca. 120 nm. The NIR/MR-MSNs show not only near-infrared fluorescence imaging property with an emission peak at 794 nm, but also highly MRT1relaxivity of 14.54 mM−1 s−1, which is three times more than Gd-DTPA. In vitro experiment reveals high uptake and retention abilities of the nanoprobes, while cell viability assay demonstrates excellent cytocompatibility of the dual-modality imaging probe. After intratumor injection with the NIR/MR-MSNs, MR imaging shows clear anatomical border of the enhanced tumor region while NIR fluorescence exhibits high sensitive tumor detection ability. These intriguing features suggest that this newly developed dual-modality imaging probes have great potential in biomedical imaging.

Highlights

Magnetic resonance (MR) and near-infrared (NIR) fluorescence have been widely used as powerful imaging tools in biomedical areas [1,2,3,4,5,6]
NIR dye has been modified onto MRdetectable nanomaterials such as superparamagnetic iron oxide nanoparticles (SPIONs) to build MR/NIR bimodal imaging probe [14,15,16]
Transmission electron microscopy (TEM) images show that mesoporous silica nanoparticles (MSNs)-NH2 have a truncatedoctahedral shape with a mean diameter about 120 nm (Figures 2(a)–2(c))

Summary

Introduction

Magnetic resonance (MR) and near-infrared (NIR) fluorescence have been widely used as powerful imaging tools in biomedical areas [1,2,3,4,5,6]. Due to the inherent limitations of MR and NIR, it is still impossible to get molecular, functional, and anatomical information by signal imaging method [1, 2, 7, 8]. The black SPIONs can directly quench the fluorescence of the dye. Surface modifications are commonly needed to connect functional molecules, which makes the SPION based dual-modality probes even more complicated [14]. Another method is conjugating MR agents with semiconductor quantum dots (QDs) [1, 17,18,19]. The drawback of the toxicity of heavy cadmium metal makes QD based imaging probes potential clinical usage limited [1]

Methods

Results

Conclusion