Spaser as a biological probe

Abstract

Understanding cell biology greatly benefits from the development of advanced diagnostic probes. Here we introduce a 22-nm spaser (plasmonic nanolaser) with the ability to serve as a super-bright, water-soluble, biocompatible probe capable of generating stimulated emission directly inside living cells and animal tissues. We have demonstrated a lasing regime associated with the formation of a dynamic vapour nanobubble around the spaser that leads to giant spasing with emission intensity and spectral width >100 times brighter and 30-fold narrower, respectively, than for quantum dots. The absorption losses in the spaser enhance its multifunctionality, allowing for nanobubble-amplified photothermal and photoacoustic imaging and therapy. Furthermore, the silica spaser surface has been covalently functionalized with folic acid for molecular targeting of cancer cells. All these properties make a nanobubble spaser a promising multimodal, super-contrast, ultrafast cellular probe with a single-pulse nanosecond excitation for a variety of in vitro and in vivo biomedical applications.

Temperature-dependent optical properties of gold thin films

“…Table 2 shows the same for thinner films at the same wavelength. Note that the propagation lengths and LSPR Q at room temperature in the thinner films are 9 significantly smaller than that in thicker samples and the observed relative change is also larger.…”

“…Therefore, probing the temperature dependence of the optical properties of thin metal films is critical for both gaining an insight into the physical process associated with elevated temperatures and for accurate modeling of devices for high-temperature applications. Incorporating temperature dependence into causal experiment-fitted material models would be crucial for time-domain numerical studies of plasmonic elements 8 , such as for spasers 9 , plasmonic nanolasers 10,11 and plasmon-assisted photocatalysis 12,13 .…”

Coulomb and quenching effects in small nanoparticle-based spasers

“…The small spaser size well below the diffraction limit gives rise to numerous promising applications, e.g., in sensing [13] or medical diagnostics [15]. However, most experimental realizations of spaser-based nanolasers were carried in relatively large systems, while only a handful of experiments reported spasing action in small systems with overall size below 50 nm [4,15].…”

“…First observed in gold nanoparticles (NP) coated by dye-doped dielectric shells [4], spasing action was reported in hybrid plasmonic waveguides [5], semiconductor quantum dots on metal film [6,12], plasmonic nanocavities and nanocavity arrays [7-9, 11, 13, 14], metallic NP and nanorods [10,15], and recently was studied in graphenebased structures [16]. The small spaser size well below the diffraction limit gives rise to numerous promising applications, e.g., in sensing [13] or medical diagnostics [15]. However, most experimental realizations of spaser-based nanolasers were carried in relatively large systems, while only a handful of experiments reported spasing action in small systems with overall size below 50 nm [4,15].…”

“…The prediction of plasmonic laser (spaser) [1][2][3] and its experimental realization in various systems [4][5][6][7][8][9][10][11][12][13][14][15] have been among the highlights in the rapidly developing field of plasmonics during the past decade [17]. First observed in gold nanoparticles (NP) coated by dye-doped dielectric shells [4], spasing action was reported in hybrid plasmonic waveguides [5], semiconductor quantum dots on metal film [6,12], plasmonic nanocavities and nanocavity arrays [7-9, 11, 13, 14], metallic NP and nanorods [10,15], and recently was studied in graphenebased structures [16].…”