In this work, near-infrared fluorescence (NIRF) and magnetic resonance (MR) dual-modality imaging probes are prepared by conjugating maleimide derivative cyanine dye (Mal-Cy5.5), gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA), and RGD peptide (Mal-PEG2-RGD) on thioether-bridged mesoporous organosilica nanoparticles (MONs) via click reaction. Fourier transform infrared (FT-IR) spectra, zeta potentials, UV-vis spectra, and energy dispersive X-ray (EDX) spectrum confirm the successful modifications of the functional molecules on the MONs. The prepared MON-Gd-Cy5.5-RGD probes shows excellent NIRF and MR imaging properties, and the relaxivity rate (r1) is measured up to 2.85 mM(-1)s(-1). In addition, the MON-Gd-Cy5.5-RGD probes show excellent in vitro and in vivo biocompatibility. Confocal laser scanning microscopy and flow cytometry demonstrate that the MON-Gd-Cy5.5-RGD can efficiently target to MDA-MB-231 tumor cells. Additionally, ex vivo NIFR and in vivo MR imaging demonstrate that the MON-Gd-Cy5.5-RGD probes can accumulate in tumor and improve the signals of tumor. (C) 2018 Elsevier Inc. All rights reserved.