Local electric field and scattering cross section on Ag nanoparticles were evaluated by the FDTD (finite difference time domain) method with respect to single-molecule sensitivity (SMS) in SERS (surface-enhanced Raman scattering). As a result, (1) vast enhancement of >300-fold (in amplitude enhancement) SMS level was obtained at junction between two connecting particles various shapes sizes addition an edge isolated triangular cylinders. Other sites circular ellipsoidal cylinders gave only...

The formation of narrow size dispersed and nanometer aggregates (clusters) cadmium selenide (CdSe) quantum dots (QDs) their temperature-sensitive photoluminescence (PL) spectral properties close to room temperature (298 K) are discussed. CdSe QDs formed stable clusters with an average diameter ∼27 nm in the absence coordinating solvents. Using transmission electron microscopy (TEM) imaging, we identified association individual 2−5 diameters into uniform size. A suspension these different...

The present study examined the potential of quantum dot bioconjugates to sensitize cells UV irradiation and promote photodynamic activity classical photosensitizers such as trifluoperazine (TFPZ) sulfonated aluminum phthalocyanine (SALPC). Water-soluble CdSe nanocrystals were conjugated with anti-CD antibody known specificity leukemia cells. Quantum conjugates incubated cell line Jurkat ensure specific interaction surface. This was confirmed by fluorescent confocal microscopy. Furthermore,...

Structures and properties of CdSe quantum dots (clusters) up to a diameter ∼2 nm were investigated by combining experimental absorption, photoluminescence (PL), X-ray diffraction (XRD) spectroscopies as well ab initio DFT calculations. These clusters nucleated grown from solutions containing respective cadmium selenium precursors following the hot-injection technique that allows one obtain size-controlled having PL efficiency 0.5. The calculations performed at B3LYP/Lanl2dz level followed...

The electromagnetic (EM) enhancement in surface-enhanced resonance Raman scattering (SERRS) is quantitatively evaluated for rhodamine molecules adsorbed on Ag nanostructures. Polarization dependence of the plasma (plasmon resonance) and SERRS spectra from single isolated nanostructures was to determine one-to-one relationship between optical anisotropy resonance, that SERRS, morphology Experimental observations were compared with finite-difference time-domain calculations EM field induced by...

Development of quantum dot (QD) based device components requires controlled integration QDs into different photonic and electronic materials. In this regard, introduction methods for regular arrangement investigation properties QD-based assemblies are important. the current work we report (1) conjugation CdSe−ZnS to sidewall-functionalized single-walled carbon nanotube (SWCNT) templates (2) effect SWCNT on photoluminescence (PL) QDs. We identified that PL intensity lifetime considerably...

Evidence of ``twofold'' electromagnetic (EM) enhancement in surface-enhanced resonance Raman scattering (SERRS) that exhibits a SERRS factor up to ${10}^{14}$ has been analyzed by comparing spectra and plasmon Rayleigh spectra. We identified spectral variations are induced selective bands whose maxima close maxima. The correlation between the energy demonstrated second EM as result coupling photons plasmons.

We identified an insect neuropeptide, namely, allatostatin 1 from Drosophila melanogaster, that transfects living NIH 3T3 and A431 human epidermoid carcinoma cells transports quantum dots (QDs) inside the cytoplasm even nucleus of cells. QD-conjugated biomolecules are valuable resources for visualizing structures functions biological systems both in vivo vitro. Here, we selected 1, Ala-Pro-Ser-Gly-Ala-Gln-Arg-Leu-Tyr-Gly-Phe-Gly-Leu−NH2, conjugated to streptavidin-coated CdSe−ZnS QDs. This...

Efficient intracellular delivery of quantum dots (QDs) and unravelling the mechanism underlying are essential for advancing applications QDs toward in vivo imaging therapeutic interventions. Here, we show that clathrin-mediated endocytosis is most important pathway peptide-conjugated QDs. We selected an insect neuropeptide, namely, allatostatin (AST1, APSGAQRLYG FGL-NH2), conjugated it with CdSe−ZnS QDs, investigated conjugate living cells such as human epidermoid ovarian carcinoma (A431)...

We analyze blinking in surface enhanced resonance Raman scattering (SERRS) and fluorescence (SEF) of rhodamine 6G molecules as intensity spectral instability by electromagnetic (EM) mechanism. find that irradiation intense NIR laser pulses induces SERRS SEF. Thanks to the finding, we systematically SEF from stable unstable using single Ag nanoparticle (NP) dimers. The analysis reveals two physical insights into follows. (1) is inversely proportional enhancement factors decay rate molecules....

Temperature dependence of blinking in SERS (surface enhanced raman scattering) signal, which is abrupt repeated intensity and peak frequency fluctuation, was studied. It found that the observed at room temperature (RT) suppressed by cooling to 77 K for one-third one-fourth particles recovered warming RT. Accordingly, thermally activated, e.g., diffusion molecules between different sites on Ag particles. These are possibly attributed junctions touching with enormously large electric fields...

We investigated the optical properties of isolated single aggregates Ag nanoparticles (Ag nanoaggregates) on which rhodamine 6G molecules were adsorbed to reveal experimentally a correlation among plasmon resonance Rayleigh scattering, surface-enhanced Raman scattering (SERRS), and its background light emission. From lack excitation-laser energy dependence emission maxima we concluded that is luminescence, not scattering. The polarization both SERRS was same as lowest-energy maxima,...

Photoluminescence (PL) quantum efficiencies and lifetimes of CdSe dots (QDs) were investigated under photoactivation in different chemical environments including polymer solutions solvent systems. We observed considerable enhancement the PL efficiency QDs when photoactivated above band gap presence polymers such as poly(dimethyl siloxane) (PDMS), poly(vinyl pyrrolidone) (PVP), poly(butadiene) (PBD). Furthermore, spectra enhanced considerably stabilized continuous dissolved polymers. Under...

We examined an electromagnetic (EM) theory of surface-enhanced resonance Raman scattering (SERRS) using single Ag nanoaggregates. The SERRS-EM is characterized by twofold EM enhancement induced the coupling plasmon with both excitation and emission plus fluorescence. total cross-section spectra enhanced fluorescence were calculated following parameters: spectrum factor resonance, overlapped fluorescence, wavelengths. calculations well agreed experimental spectra, thus providing strong...

Intermittent “on” and “off” (blinking) photoluminescence (PL) of single-CdSe/ZnS quantum dots (QDs) is modified when placed on an Ag nanoparticle (NP) film into stochastic fluctuations with nonzero intensity (pseudo off) periods. Also, the PL efficiency (from 0.42 to 0.22) lifetime 5.2 1.5 ns) QDs are considerably decreased at ensemble level in presence NPs, a histogram single-QDs shifted 4.2 1.7 tapered (full width half-maximum from 3.3 1.1 NP film. The quenching decrease attributed...

The photoluminescence of semiconductor quantum dots and fluorescence single molecules intermittently turn ON OFF, a phenomenon referred to as blinking. In dots, blinking occurs result intermittent Auger ionization, which results in the formation positively charged dots. Due strong Coulombic interactions, successive photoactivation dot nonradiative carrier recombination, inducing long-lived OFF states intensity trajectories. Blinking is an undesirable property with respect applications toward...

Replica microchips for capillary array electrophoresis containing 10 separation channels (50 µm width, 50 depth and 100 pitch) a network of sacrificial (100 width depth) were successfully fabricated on poly(methyl methacrylate) (PMMA) substrate by injection molding. The strategy involved development moving mask deep X-ray lithography to fabricate an with inclined channel sidewalls. A slight inclination sidewalls, which can not be conventional lithography, is highly required ensure the...

We labeled the living yeast cell surface (Saccharomyces cerevisiae strain W303-1A) by silver nanoparticles which can form nanoaggregates and found to show enhanced Raman scattering (SERS) activity. Blinking of SERS its polarization dependence reveal that signals are from amplified electromagnetic field at nanometric Ag gaps with single or a few molecules sensitivity. tentatively assigned spectra wall mannoproteins. Nanoaggregate-by-nanoaggregate variations temporal fluctuations discussed in...

Quantum dots-based electron donor-acceptor systems play a rising role in the design of renewable and carbon-free energy harvesting technologies. In this article, we discuss photofabrication fullerene-shelled quantum dots supramolecular nanoparticles, which fullerene shell acts as not only well-defined acceptor but also robust protecting layer against photocorrosion dot core. We evaluate ensemble single-molecule transfer from core to nanoparticles photocurrent response photoelectrochemical...