Spaser as a biological probe Galanzha, Ekaterina I; Weingold, Robert; Nedosekin, Dmitry A ...
Nature communications,
06/2017, Volume:
8, Issue:
1
Journal Article
Peer reviewed
Open access
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.
A radiation-resistant diamond-based detector for registration of fluxes of particles of cosmic radiation with low linear energy transfer is developed and investigated. The device may be used to ...register gamma radiation of water-moderated, water-cooled nuclear energy reactors. The characteristics of a detector when exposed to beta radiation are determined and modeling of the signals of the device when exposed to beta and gamma radiation is performed. The use of a multi-layer diamond structure makes it possible to increase the signal-to-noise ratio and expand the dynamic range of measurements of the linear energy transfer of cosmic radiation particles.
We fabricated neutron detectors based on thin epitaxial CVD diamond films grown on single crystal diamond substrates, with a buried graphitic electrode produced by ion implantation and annealing. The ...spectra of 5.5 MeV alpha particles were measured with ≈3.5% energy resolution, and, based on the features of those spectra, a precise assessment of the film thickness was able achieved. A 10 μm thick detector was tested for 252Cf neutron and γ-radiation source, using 10B and 6Li isotopes as converters. Due to the small film thickness the contribution from the γ-quanta background to the spectra was restricted by energies below 200 keV, and could be easily discriminated from the neutron related signals. The performance of the detectors was tested for 5.5 MeV α-particles at fluences up to 109cm−2, and no detrimental polarization effect was observed for the best sample.
This work is devoted to study of the diamond based radiation detectors. Experiments were carried out with two types of detectors: based on a thin diamond film and on a composite diamond plate. The ...following types of ionizing radiation has been used in experiments: beta radiation of 90Sr - 90Y, fission fragments and alpha particles of 252Cf, and Kr ions obtained at the particle accelerator. It is shown that the developed thin-film diamond based detector effectively registers heavy charged particles, whereas beta, neutron and gamma radiation does not give a significant contribution to the detector signals. Those type of detectors are proposed for measurement of heavy charged particles linear energy transfer in diamond. The multilayer diamond based detector (detector with a composite diamond plate) showed improved charge collection efficiency values in compare with the detection with a single diamond plate.
We have studied the gamma sensitivity of single-crystal CVD diamond neutron detectors using a
252
Cf neutron source placed in a moderator. It has been shown that a major contribution to the count ...rate of the detectors is made by the gamma rays from the source. We have compared the count rates of a detector with a
10
B boron isotope-based slow-neutron converter and without it. With allowance for the theoretically calculated detection efficiency, the difference between the count rates is consistent with the fraction of slow neutrons measured using a scintillation detector.
A mathematical model is developed for a multichannel sensor unit based on diamond detectors in a device for monitoring the parameters of cosmic ray fluxes. The output signals from these sensors are ...modelled as they detect ionizing radiation from outer space in different spacecraft orbits with various levels of solar activity.
In this work we study influence of various factors on stability of ionizing radiation detectors installed in the cosmic ray spectrometer (SCR) based on diamond detectors of ionization radiation ...(DDIR). Diamond detectors for SCR are made of single crystals of synthetic diamond type IIa. Diamond detectors were studied successively in three different experiments. Checking detector stability with ambient temperature increased up to 70 degrees Celsius was the first experiment. At next we change the geometry of detector irradiation by rotating nuclear source around it and measuring changes in detector count rate. And last one experiment was about checking the phenomenon of polarization by prolonged detector irradiation by ionizing radiation of various types and energies. The study revealed the presence of the strong influence of the polarization effect on the work of diamond detectors for registration of ionizing particles with short mean free path (in our experiment they were the alfa-particles of 238Pu). In this work correspondence of the experimental results of the "rotation" the source around the detector with the data obtained by simulation in GEANT-4 was shown.
Were conducted a series of experiments, the purpose of which had to verify the mathematical model of the radiation environment sensor. Theoretical values of the beta particles count rate from 90Sr - ...90Y source registered by radiation environment sensor was compared with the experimental one. Theoretical (calculated) count rate of beta particles was found with using the developed mathematical model of the radiation environment sensor. Deviation of the calculated values of the beta particle count rate does not exceed 10% from the experimental.
Theoretical approaches to the construction of a spectrometric diamond detector of fluxes of ionizing radiation are considered. The device is intended for continuous monitoring of the radiation ...conditions onboard space vehicles for quickly arriving at decisions as regards active protection and prediction of the remaining life of space transportation systems.
The article describes the device for selective registration of electrons, protons and heavy ions fluxes from the solar and galactic cosmic rays in the twelve energy ranges, built on a base of diamond ...detector. The use of the diamond detectors allowed for the creation a device for registration of cosmic particles fluxes at the external spacecraft surface with the resource not less than 20 years. Selective detector is aimed for continuous monitoring of radiation situation on board the spacecrafts, in order to predict the residual life of their work and prompt measures to actively protect the spacecraft when the flow of cosmic particles is sharply increased.
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