Sub-100 nm colloidal particles which are surface-functionalized with multiple environmentally-sensitive moieties have the potential to combine imaging, early detection, and the treatment of cancer with a single type of long-circulating "nanodevice". Deep tissue imaging is achievable through the development of particles which are surface-modified with fluorophores that operate in the nearinfrared (NIR) spectrum and where the fluorophore's signal can be maximized by "turning-on" the fluorescence only in the targeted tissue. We present a general approach for the synthesis of NIR emitting nanoparticles that exhibit a protein triggered activation/deactivation of the emission.Dispersing the particles into an aqueous solution, such as phosphate buffered saline (PBS), resulted in an aggregation of the hydrophobic fluorophores and a cessation of emission. The emission can be reinstated, or activated, by the conversion of the surface-attached fluorophores from an aggregate to a monomeric species with the addition of an albumin. This activated probe can be deactivated and returned to a quenched state by a simple tryptic digestion of the albumin. The methodology for emission switching offers a path to maximize the signal from the typically weak quantum yield inherent in NIR fluorophores.

The alternating current (AC) and direct current (DC) electrical response of a number of n-alkyl methacrylate polymers with a charge transporting pendant carbazole ring were studied.

Composite nanoclusters with chemical, magnetic, and biofunctionality offer broad opportunities for targeted cellular imaging. A key challenge is to load a high degree of targeting, imaging, and therapeutic functionality onto stable metal-oxide nanoparticles. Here we report a route for producing magnetic nanoclusters (MNCs) with alkyne surface functionality that can be utilized as multimodal imaging probes. We form MNCs composed of magnetic Fe(3)O(4) nanoparticles and poly(acrylic acid-co-propargyl acrylate) by the co-precipitation of iron salts in the presence of copolymer stabilizers. The MNCs were surface-modified with near-infrared (NIR) emitting fluorophore used in photodynamic therapy, an azide-modified indocyanine green. The fluorophores engaged and complexed with bovine serum albumin, forming an extended coverage of serum proteins on the MNCs. These proteins isolated indocyanine green fluorophores from the aqueous environment and induced an effective "turn-on" of NIR emission.

We present a general approach for the selective imaging and killing of cancer cells using protein-activated near-infrared emitting and cytotoxic oxygen generating nanoparticles. Poly(propargyl acrylate) (PA) particles were surface modified through the copper-catalyzed azide/alkyne cycloaddition of azide-terminated indocyanine green (azICG), a near-infrared emitter, and poly(ethylene glycol) (azPEG) chains of various molecular weights. The placement of azICG onto the surface of the particles allowed for the chromophores to complex with bovine serum albumin when dispersed in PBS that resulted in an enhancement of the dye emission. In addition, the inclusion of azPEG with the chromophores onto the particle surface resulted in a synergistic ninefold enhancement of the fluorescence intensity, with azPEGs of increasing molecular weight amplifying the response. Human liver carcinoma cells (HepG2) overexpress albumin proteins and could be employed to activate the fluorescence of the nanoparticles. Preliminary PDT studies with HepG2 cells combined with the modified particles indicated that a minor exposure of 780 nm radiation resulted in a statistically significant reduction in cell growth.

The current effort demonstrates that lutetium oxyorthosilicate doped with 1–10% cerium (Lu2SiO5:Ce, LSO:Ce) radioluminescent particles can be coated with a single dye or multiple dyes and generate an effective energy transfer between the core and dye(s) when excited via X-rays. LSO:Ce particles were surface modified with an alkyne modified naphthalimide (6-piperidin-1-yl-2-prop-2-yn-1-yl-1H-benzo­[de]­isoquinoline-1,3-(2H)-dione, AlNap) and alkyne modified rhodamine B (N-(6-diethylamino)-9-{2-[(prop-2-yn-1-yloxy)­carbonyl]­phenyl}-3H-xanthen-3-ylidene)-N-ethylethanaminium, AlRhod) derivatives to tune the X-ray excited optical luminescence from blue to green to red using Förster Resonance Energy Transfer (FRET). As X-rays penetrate tissue much more effectively than UV/visible light, the fluorophore modified phosphors may have applications as bioimaging agents. To that end, the phosphors were incubated with rat cortical neurons and imaged after 24 h. The LSO:Ce surface modified with AlNap was able to be successfully imaged in vitro with a low-output X-ray tube. To use the LSO:Ce fluorophore modified particles as imaging agents, they must not induce cytotoxicity. Neither LSO:Ce nor LSO:Ce modified with AlNap showed any cytotoxicity toward normal human dermal fibroblast cells or mouse cortical neurons, respectively.