The present invention provides a safe polymer nanoparticle composite with few side effects, and an MRI contrast agent incorporating said polymer nanoparticle composite. The polymer nanoparticle composite is capable of specifically accumulating on a tumor tissue to selectively extract the tissue, exhibiting high contrast even when used in small amounts, and enabling imaging over prolonged periods of time. This polymer nanoparticle composite is characterized by containing a block copolymer that includes a non-charged hydrophilic polymer chain segment and an anionic polymer chain segment, and MnCaP.

Described are compositions and methods of manufacturing extracellular vesicles comprising sticky imaging particles. In one aspect, methods include associating a sticky element to imaging particles forming sticky imaging particles. The sticky imaging particles are associated with extracellular vesicles (EV) to form a mixture comprising extracellular vesicles (EV) that comprise sticky imaging particles. The method also include separating the sticky imaging particles associated with EVs from sticky imaging particle that are not associated with EVs.

Polyarginine-coated nanoparticle, and methods for making and using the nanoparticle. The nanoparticle can have a core that includes a material that imparts magnetic resonance imaging activity to the particle and, optionally, include one or more of an associated therapeutic agent, targeting agent, and diagnostic agent.

We have developed a model system of HIV reservoirs in neural cells by generating chimeric phosphorothioate-modified oligodeoxynucleotides (sODN) that specifically interact with neural cell DNA or RNA, and that further comprise a sequence of the HIV genome. In particular, we have conjugated the chimera sODN to a delivery vehicle (e.g. a superparamagnetic iron oxide nanoparticle (SPIO)) and have demonstrated specific delivery to neural cells, in vitro and in vivo. These model systems can be used to screen for agents that specifically target latent viral infection. In particular, using the model system, we have developed suicide MRI contrast agents that can be used to reduce the number of neural cells which harbor the virus, also provided herein. Our model system is translatable to other latent viruses as well.

An MRI contrast agent, including superparamagnetic nanoparticles and hydroxyethyl starch. The weight ratio of the superparamagnetic nanoparticles to the hydroxyethyl starch is between 1:5 and 1:15. The superparamagnetic nanoparticles have a particle size of 100-140 nm, and include the following layers, from the inside out, ferrous ferric oxide particles, citric acid, and poly-R-lysine. The citric acid accounts for 6-13 wt. % of the ferrous ferric oxide particles. The poly-R-lysine accounts for 6-20 wt. % of the ferrous ferric oxide particles.

Composition and method for surface-functionalized SPION-based agents. Such agents can provide highly pH-sensitive MRI contrast in tissue.