The fluorine atom provides an exciting tool for diverse spectroscopic and imaging applications using Magnetic Resonance. The organic chemistry of fluorine is widely established and it can provide a stable moiety for interrogating many aspects of physiology and pharmacology in vivo. Strong NMR signal, minimal background signal and exquisite sensitivity to changes in the microenvironment have been exploited to design and apply diverse reporter molecules. Classes of agents are presented to investigate gene activity, pH, metal ion concentrations (e.g., Ca(2+), Mg(2+), Na(+)), oxygen tension, hypoxia, vascular flow and vascular volume. In addition to interrogating speciality reporter molecules, (19)F NMR may be used to trace the fate of fluorinated drugs, such as chemotherapeutics (e.g., 5-fluorouracil, gemcitabine), anesthetics (e.g., isoflurane, methoxyflurane) and neuroleptics. NMR can provide useful information through multiple parameters, including chemical shift, scalar coupling, chemical exchange and relaxation processes (R1 and R2). Indeed, the large chemical shift range (approximately 300 ppm) can allow multiple agents to be examined, simultaneously, using NMR spectroscopy or chemical shift selective imaging.

19 F NMR spin-lattice relaxometry of hexafluorobenzene (HFB) has been shown to be a highly sensitive indicator of tumor oxygenation. In this study hexamethyldisiloxane (HMDSO) was identified as a proton NMR analog, and its potential as a probe for investigating dynamic changes in tissue oxygen tension (pO 2 ) was evaluated. HMDSO has a single proton resonance ‫؍␦(‬ -0.3 ppm) and the spin-lattice relaxation rate, R l ‫؍(‬ 1/T 1 ) exhibits a linear dependence on pO 2 : R 1 (s -1 ) ‫؍‬ 0.1126 ؉ 0.0013* pO 2 (torr) at 37°C. To demonstrate application in vivo, HMDSO was administered into healthy rat thigh muscle (100 l) and tumors (50 l). Local pO 2 was determined by using pulse-burst saturation recovery (PBSR) 1 H NMR spectroscopy to assess R 1 . Water and fat signals were effectively suppressed by frequency-selective excitation of the HMDSO resonance. Rat thigh muscle had a mean baseline pO 2 of 35 ؎ 11 torr, with a typical stability of ؎3 torr over 20 min, when the rats breathed air. Altering the inhaled gas to oxygen produced a significant increase in pO 2 to 100 -200 torr. In tumors, altering the inspired gas also produced significant (

Previously uncharacterized poly(N-isopropylacrylamide-acrylamide-allylamine)-coated magnetic nanoparticles (MNPs) were synthesized using silane-coated MNPs as a template for radical polymerization of N-isopropylacrylamide, acrylamide, and allylamine. Properties of these nanoparticles such as size, biocompatibility, drug loading efficiency, and drug release kinetics were evaluated in vitro for targeted and controlled drug delivery. Spherical core-shell nanoparticles with a diameter of 100 nm showed significantly lower systemic toxicity than did bare MNPs, as well as doxorubicin encapsulation efficiency of 72%, and significantly higher doxorubicin release at 41°C compared with 37°C, demonstrating their temperature sensitivity. Released drugs were also active in destroying prostate cancer cells (JHU31). Furthermore, the nanoparticle uptake by JHU31 cells was dependent on dose and incubation time, reaching saturation at 500 μg/mL and 4 hours, respectively. In addition, magnetic resonance imaging capabilities of the particles were observed using agarose platforms containing cells incubated with nanoparticles. Future work includes investigation of targeting capability and effectiveness of these nanoparticles in vivo using animal models. KeywordsMagnetic nanoparticles; Temperature-responsive polymers; Prostate cancer; Doxorubicin Magnetic nanoparticles (MNPs) coated with temperature-sensitive polymers have been attracting great attention because of their various applications in the fields of biotechnology and medicine. In particular, temperature-sensitive coated MNPs have been used extensively in controlled and targeted drug release systems.1 -4 These nanocomposites are superior to the traditional stimuli-responsive systems such as pH and temperature-sensitive polymers, because

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Reporter genes and associated enzyme activity are becoming increasingly significant for research in vivo. The lacZ gene and b-galactosidase (b-gal) expression have long been exploited as reporters of biologic manipulation at the molecular level, and a noninvasive detection strategy based on proton MRI is particularly attractive. 3,4-Cyclohexenoesculetin b-D-galactopyranoside (S-GalV R ) is a commercial histologic stain, which forms a black precipitate in the presence of bgal and ferric ions, suggesting potential detectability by MRI. Generation of the precipitate is now shown to cause strong T 2 * relaxation, revealing b-gal activity. A series of tests with the enzyme in vitro and with tumor cells shows that this approach can be used as an assay for b-gal activity. Proof of principle is shown in human breast tumor xenografts in mice. Reporter genes are routinely used to reveal genetic manipulations and have become a mainstay of molecular biology. More recently, they have been applied to in vivo investigations, and fluorescent proteins and bioluminescence based on luciferase are effective for small animal investigations. However, the bacterial lacZ gene has been the most popular reporter, with applications ranging from immunosorbent assays to in situ hybridizations and evaluation of gene distribution. Indeed, lacZ has been used in clinical trials revealing regions of tissue transfection in biopsy specimens based on histologic staining. As such, many colorimetric stains and assays have been developed and are in routine use, including reagents such as nitrophenyl-b-D-galactopyranoside, which generates a yellow coloration, 4-chloro-3-bromoindole-galactose, which generates a blue stain, and 3,4-cyclohexenoesculetin b-D-galactopyranoside, which generates a black stain.In vivo detection could be very valuable, and several recent studies have reported novel substrates or novel applications of substrates allowing detection of b-galactosidase. b-Gal shows broad substrate specificity, and recent in vivo applications have exploited fluorescence of 7-hydroxy-9H-(1,3-dichloro-9,9-dimethylacridin-2-one- In terms of NMR, Louie et al. (8) proposed a galactose capped gadolinium ligand in 2000, which showed an increased relaxivity upon exposure to b-gal. Following direct intracellular injection into oocytes, it could elegantly reveal cell lineage in developing tadpoles. Unfortunately, the requirement for direct intracellular injection precluded use in tumors. These studies prompted us to seek alternate NMR reporters.We have presented a variety of substrates based on isomers and analogs of 4-fluoro-2-nitrophenyl-b-D-galactopyranoside (9-11), which exhibit 19 F NMR chemical shift change due to b-gal activity. We have shown the ability to differentiate wild-type (WT) and stably transfected lacZ expressing breast and prostate tumor xenografts implanted in mice using 19 F NMR (12,13). Detection would ideally use systemic delivery of the reporter molecules, but to date we have achieved measurements based on direct intratumoral injection...