68 research outputs found
Optical response of metal nanoparticle chains
We study the optical responses of metal nanoparticle chains. Multiple
scattering calculations are used to study the extinction cross sections of
silver nanosphere chains of finite length embedded in a glass matrix. The
transmission and reflection coefficients of periodic 2D arrays of silver
nanospheres are also calculated to understand the interaction between
nanoparticle chains. The results are in agreement with recent experiments. The
splitting of plasmon-resonance modes for different polarizations of the
incident light are explored. Results on the effect of disorder are also
presented.Comment: 9 pages, 10 figure
Improved Cellular Specificity of Plasmonic Nanobubbles versus Nanoparticles in Heterogeneous Cell Systems
The limited specificity of nanoparticle (NP) uptake by target cells associated with a disease is one of the principal challenges of nanomedicine. Using the threshold mechanism of plasmonic nanobubble (PNB) generation and enhanced accumulation and clustering of gold nanoparticles in target cells, we increased the specificity of PNB generation and detection in target versus non-target cells by more than one order of magnitude compared to the specificity of NP uptake by the same cells. This improved cellular specificity of PNBs was demonstrated in six different cell models representing diverse molecular targets such as epidermal growth factor receptor, CD3 receptor, prostate specific membrane antigen and mucin molecule MUC1. Thus PNBs may be a universal method and nano-agent that overcome the problem of non-specific uptake of NPs by non-target cells and improve the specificity of NP-based diagnostics, therapeutics and theranostics at the cell level
Annealing Effects on Structure and Optical Properties of Diamond-Like Carbon Films Containing Silver
On the Enhanced Antibacterial Activity of Antibiotics Mixed with Gold Nanoparticles
<p>Abstract</p> <p>The bacterial action of gentamicin and that of a mixture of gentamicin and 15-nm colloidal-gold particles on<it>Escherichia coli</it>K12 was examined by the agar-well-diffusion method, enumeration of colony-forming units, and turbidimetry. Addition of gentamicin to colloidal gold changed the gold color and extinction spectrum. Within the experimental errors, there were no significant differences in antibacterial activity between pure gentamicin and its mixture with gold nanoparticles (NPs). Atomic absorption spectroscopy showed that upon application of the gentamicin-particle mixture, there were no gold NPs in the zone of bacterial-growth suppression in agar. Yet, free NPs diffused into the agar. These facts are in conflict with the earlier findings indicating an enhancement of the bacterial activity of similar gentamicin–gold nanoparticle mixtures. The possible causes for these discrepancies are discussed, and the suggestion is made that a necessary condition for enhancement of antibacterial activity is the preparation of stable conjugates of NPs coated with the antibiotic molecules.</p
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