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Colloidal stability of nanoparticles in biological media is an important consideration when trying to ensure reliable data interpretation of in vitro and in vivo systems. We have developed a detailed colloidal stability library of newly synthesized gold, silver and gold-core silver-shell plasmonic nanoparticles, stabilized with aspartame, glucosamine and sucralose, in various biologically relevant buffers and bacterial and mammalian cell culture media. The stabilizer selection reflects the preference for molecules that are non-toxic, inexpensive, readily available, water soluble and easy-to-replace if that is the end-user preference. An on-line resource provides detailed stability information on each of the 81 systems examined. To illustrate how to utilize this stability library, we conducted bacterial toxicity and biocompatibility experiments through the use of one specific set of nanomaterials in the presence and absence of plasmonic irradiation.

Comparable intracellular concentrations (≈30pmol/10(6) cells) of bovine serum albumin-ZnPc (BSA) adduct outperformed dipalmitoyl-phosphatidyl-choline (DPPC) liposomes containing ZnPc at photodynamic-killing of human cervical cancer cells (HeLa) after only 15min of irradiation using red light (λ>620nm, 30W/cm(2)). This result could not be simply explained in terms of dye aggregation within the carrier, since in the liposomes the dye was considerably less aggregated than in bovine serum albumin, formulation that was capable to induce cell apoptosis upon red light exposure. Thus, using specific organelle staining, our cumulative data points towards intrinsic differences in intra-cellular localization depending on the cargo vehicle used, being ZnPc:BSA preferentially located in the near vicinity of the nucleus and in the Golgi structures, while the liposomal formulation ZnPc:DPPC was preferentially located in cellular membrane and cytoplasm. In addition to those differences, using real-time advanced fluorescence lifetime imaging of HeLa cells loaded with the photosensitizer contained in the different vehicles, we have found that only for the ZnPc:BSA formulation, there was no significant changes in the fluorescence lifetime of the photosensitizer inside the cells. This contrasts with the in situ≈two-fold reduction of the fluorescence lifetime measured for the liposomal ZnPc formulation. Those observations point towards the superiority of the protein to preserve dye aggregation, and its photochemical activity, post-cell uptake, demonstrating the pivotal role of the delivery vehicle at determining the ultimate fate of a photosensitizer.

Plasmon excitation of spherical gold nanoparticles carrying a fluorescent labeled 30 bp dsDNA cargo, with one chain covalently attached through two S–Au bonds to the surface, results in release of the complementary strand as ssDNA that can be examined in situ using high-resolution fluorescence microscopy. The release is dependent on the total energy delivered, but not the rate of delivery, an important property for plasmonic applications in medicine, sensors, and plasmon-induced PCR. Fil: Simoncelli, Sabrina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones en Bionanociencias "Elizabeth Jares Erijman"; Argentina. University of Ottawa; Canadá Fil: Alwis Weerasekera, Hasitha de. University of Ottawa; Canadá Fil: Fasciani, Chiara. University of Ottawa; Canadá Fil: Boddy, Christopher N.. University of Ottawa; Canadá Fil: Aramendia, Pedro Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones en Bionanociencias "Elizabeth Jares Erijman"; Argentina Fil: Alarcon, Emilio I.. University of Ottawa; Canadá Fil: Scaiano, Juan Cesar. University of Ottawa; Canadá