This contrast agent was fabricated by encapsulating indocyanine green (ICG) in PLGA MB. The technical feasibility of concurrent structural and functional imaging was demonstrated through a series of tests in which an aqueous suspension of ICG-PLGA MB was injected into a transparent tube embedded in an Intralipid phantom at different flow rates and concentrations. Concurrent fluorescence imaging and B-mode ultrasound imaging Inhibitors,research,lifescience,medical successfully captured the changes of microbubble flow rate and concentration with high linearity and accuracy. One potential application of the proposed ICG-PLGA MB would be for the identification and characterization of peritumoral neovasculature. Enhanced coregistration between tumor structural

and functional boundaries could be achieved using US-guided near-infrared diffuse optical tomography. In a similar manner, photoacoustic imaging applications also will be implemented, for example, NP exhibiting a near-infrared (NIR) absorption can be prepared by incorporation of ICG Inhibitors,research,lifescience,medical into PLGA [61, 62]. These NPs were biocompatible in vitro and had a high NIR dye

encapsulation efficiency (>98%) and two different size fractions were obtained of ~640nm and ~390nm. Cytotoxicity studies indicated no changes in metabolic activity, proliferation, Inhibitors,research,lifescience,medical or membrane integrity. Their high optical absorption at ~800nm in combination with absence of cytotoxicity qualifies the ICG-PLGA particles as promising candidates for degradable photoacoustic contrast agents in future studies. Other nanoparticles Inhibitors,research,lifescience,medical in development include composite PLGA-magnetic particles for simultaneous drug NF-��B assay delivery and imaging [82], and these might also be applied to gene delivery in future applications. These magnetic nanoparticles were embedded in PLGA matrices (PLGA-MNP) to achieve a dual-drug delivery and imaging system and were capable of encapsulating both hydrophobic and hydrophilic drugs in a 2:1 ratio while retaining favorable biocompatibility and

cellular uptake properties. For targeted delivery of drugs, targeting ligands such as Herceptin were tested, Inhibitors,research,lifescience,medical demonstrating enhanced cellular uptake. Also, magnetic resonance below imaging was used to show improved contrast by PLGA-MNP compared to commercial contrast agents due to higher T2 relaxivity with a blood circulation half-life of ~47min in a rat model. These PLGA-based matrices may be applied to both imaging and adapted to achieve successful gene delivery. 5. Conclusions PLGA and other nanoparticle delivery systems in general have distinct advantages for gene delivery, such as protecting DNA from degradation and enhancing complex stability. PLGA-based NPs can penetrate deeply into tissues through fine capillaries and are generally taken up efficiently by cells. This allows efficient delivery and accumulation of therapeutic agents, such as conventional medicines, vaccine antigens, proteins, and genes, to target sites (tissues or organs) in the body.