Laser-induced aligned self-assembly on water surfaces.

The key to functionalize of engineered molecularly nanometer thick films lies in the ability to reproducibly control their structure. A number of factors influence the film morphology of self-assembled films on solid or liquid surfaces, such as the structure of the molecules/particles, wetting, solvent hydrodynamics, and evaporation. An important example is the deposition of amphiphilic molecules from a volatile solution, self-assembled onto a water surface at monolayer coverage. Upon evaporation, a myriad of microscopic two-dimensional (2D) crystallites forms a ruptured film lying in random orientation on the surface, resulting in "2D powders." Here we present a general technique, employing linearly polarized laser pulses and varying solvent composition to influence the assembly of molecules such as poly-benzyl-L-glutamate and alamethicin on water surfaces, resulting in ultrathin molecular films with aligned regions that point in the same direction, though macroscopically separated. The experimental results are tentatively explained by a mechanism that is based on excluded volume forces and "kick model" for the effect of laser pulses to induce molecular rotation that eventually results in an aligned pattern when the system is at a collective state.

Prostate cancer PET bioprobes: synthesis of [18F]-radiolabeled hydroxyflutamide derivatives.

Approximately 80-90% of prostate cancers are androgen dependent at initial diagnosis. The androgen receptor (AR) is present in most advanced prostate cancer specimens and is believed to have a critical role in its development. Today, treatment of prostate cancer is done by inhibition of AR using antiandrogens such as flutamide (pro-drug of hydroxyflutamide), nilutamide, and bicalutamide. However, there is currently no noninvasive imaging modalities to detect, guide, and monitor specific treatment of AR-positive prostate cancer. (R)-3-Bromo-N-(4-fluoro-3-(trifluoromethyl)phenyl)-2-hydroxy-2-methyl-propanamide [18F]-1 and N-(4-fluoro-3-(trifluoromethyl)phenyl)-2-hydroxy-2-methylpropanamide [18F]-2, derivatives of hydroxyflutamide, were synthesized as a fluorine-containing imaging agent candidates. A three-step fluorine-18 radiosynthesis route was developed, and the compounds were successfully labeled with a 10+/-3% decay corrected radiochemical yield, 95% radiochemical purity, and a specific activity of 1500+/-200 Ci/mmol end of bombardment (n = 10). These labeled biprobes not only may enable for the future quantitative molecular imaging of AR-positive prostate cancer using positron emission tomography but may also allow for image-guided treatment of prostate cancer.