Molecular imaging allows the biological processes taking place in the body to be viewed at a cellular and molecular level. Molecular imaging probe is used to visualize, characterize and quantify the processes. Nano-assembly small molecule probe provides an attractive means to precisely engineer nanomedicine with distinct biophysicochemical properties and simplify the optimization of formulation, which is an emerging and promising area that can integrate the advantages of the two kinds of molecular imaging probes with high loading capacity, effective signal amplification, preferable clearance, etc. Herein, we review main advances such as small molecules self-assembly into nanoprobes, its development and application, including fluorescent, magnetic resonance imaging, and nuclide marker labeled nano-assembly small molecules probes, as well as “smart” probes of this kind and their applications in molecular imaging.

With the development of 'omics', systems biology and molecular imaging technology, a common tendency of integration of a variety of multi-modality, multi-target imaging and theranostics technology has led to the establishment of a concept that could be called “systems molecular imaging”. It can be used to show the complexity, diversity and in vivo biological behavior and the development and progress of disease in an organism qualitatively and quantitatively at a systems level. Ultimately, systems molecular imaging should enable the physicians not only to diagnose tumors accurately but also to provide 'on the spot' treatment efficiently. It will become comprehensive research tools and technical means for life science and medical sciences.

Imaging sentinel lymph nodes (SLN) could provide us with critical information about the progression of a cancerous disease. Real-time high-resolution intraoperative photoacoustic imaging (PAI) in conjunction with a near-infrared (NIR) probe may offer opportunities for the immediate imaging for direct identification and resection of SLN or collecting tissue samples. In this work a commercially amenable synthetic methodology is revealed for fabricating luminescent carbon nanoparticles with rapid clearance properties. A one-pot "green" technique is pursued, which involved rapid surface passivation of carbon nanoparticles with organic macromolecules (e.g., polysorbate, polyethyleneglycol) in solvent-free conditions. Interestingly, the naked carbon nanoparticles are derived for the first time, from commercial food grade honey. Surface coated particles are markedly smaller (~7 nm) than previously explored particles (gold, single-walled carbon nanotubes, copper) for SLN imaging. The results indicate an exceptionally rapid signal enhancement (~2 min) of the SLN. Owing to their strong optical absorption in the NIR region, tiny size and rapid lymphatic transport, this platform offers great potential for faster resection of SLN and may lower complications caused in axillary investigation by mismarking with dyes or low-resolution imaging techniques.