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.

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The isolation of a single type of protein from a complex mixture is vital for the characterization of the function, structure, and interactions of the protein of interest and is typically the most laborious aspect of the protein purification process. In this effort, a model system was utilized to show the efficacy of synthesizing a “baited” nanoparticle to capture and recycle enzymes (proteins that catalyze chemical reactions) from crude cell lysate. Enzyme trapping and recycling was illustrated with the CARDO system, an enzyme important in bioremediation and natural product synthesis. The enzymes were baited with azide modified carbazolyl moieties attached to poly (propargyl acrylate) nanoparticles through a click transformation. MALDI-TOF and SDS-PAGE analysis indicated the single step procedure to immobilize the enzymes on the particles was capable of significantly concentrating the protein from raw lysate and sequestering all required components of the protein to maintain bioactivity. These results establish a universal model applicable to concentrating and extracting known substrate protein pairs, but it can be an invaluable tool in recognizing unknown protein-ligand affinities.

A general methodology for producing ca. 100 nm core-shell colloidal particles in which the shell has an elevated alkyne functionality and yet remains thermoplastic is presented. The availability of accessible alkyne groups on the surface of the aqueous-phase particles allows for the in situ surface modification of the particles through a copper(I) catalyzed Huisgen 1,3-dipolar cycloaddition with an azide-terminated surface agent. The core is an extensively crosslinked polymer which can be easily removed by dispersing the particles in a solvent and centrifuging and collecting the cores, leaving the solubilized shells. This allows for the complete characterization of the colloidal surface reactions in the absence of the volumetrically dominant core. The technique is demonstrated with a core-shell colloid composed of a 135 nm crosslinked polystyrene (PS) core coated with a ca. 10 nm thick uncrosslinked poly(methyl acrylate-co-propargyl acrylate) shell. Due to the applicability of this technique for generating particles useful in biomedical imaging or drug delivery applications, the core-shell particles are surface modified with a variety of azide-terminated poly(ethylene glycol) (PEG) derivatives, including a poloxamer which was terminated on either end by an azide and a naphthalimide chromophore. The resulting fluorescent particles had an absorbance at 413 nm and peak emission at 525 nm. The PEG derivatives could be attached to the particles at a grafting density of ca. 0.2-0.3 groups/nm 2 .