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Studies on threshold pressures of sonoluminescence for bubbles with different noble gases

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Science China(Physics,Mechanics & Astronomy) 2004年第4期47卷 513-520页

作者： DING Chunfeng xing da Institute of Laser Life Science South China Normal University Guangzhou 510631 China Institute of Laser Life Science South China Normal University Guangzhou 510631 China

The noble gases inside bubbles may have a profound effect on the threshold pressure of sonoluminescence (SL). In this work, the SL threshold pressures have been measured experimentally for bubbles with different noble gases. Results show that the threshold pressure increases with the decrease of molecular mass for gases inside the bubbles. The simulating temperature values at the collapse are almost equal to each other for different gas bubbles at the threshold pressures. However, when the pressure is above the threshold one, the SL mechanism satisfies the bremsstrahlung. On the basis of the experiments and simulations, we found that firstly water molecules dissociate in the process of cavitation and light emission follows; then, the noble gases ionize with the increase of temperature and the bremsstrahlung occurs. SL is a process from molecular emission to bremsstrahlung.

关键词： noble gases, threshold, molecular emission, bremsstrahlung.

THERMAL QUENCHING, INFRARED QUENCHING AND SUPRALINEARITY IN a-Si:H

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Chinese Physics Letters 1984年第2期1卷 65-68页

作者： AN da-xing Institute of Physics Academia SinicaBeijing

We have tested the temperature and incident flux dependence of photoconductivity and dual beam infrared photoconductivity spectra of a-Si:H samples in annealed states A^(* ) and A, and the light soaked states B1 and B2;and observed that they were different for the 4 different states. We believe that light exposures create two kinds of centers, which we name α and τ. A model is suggested to explain the experimental results.

关键词： annealed centers beam

New insight into photoacoustic conversion efficiency by plasmon-mediated nanocavitation： Implications for precision theranostics

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Nano Research 2017年第8期10卷 2800-2809页

作者： Yujiao Shi Sihua Yang da xing Ministry of Education Key Laboratory of Laser Life Science and Institute of Laser Life Science College of Biophotonics South China Normal University Guangzhou 510631 China

The probe-assisted integration of imaging and therapy into a single modality offers significant advantages in bio-applications. As a newly developed photoacoustic （PA） mechanism, plasmon-mediated nanocavitation, whereby photons are effectively converted into PA shockwaves, has excellent advantages for image-guided therapy. In this study, by simulating the laser absorption, temperature field, and nanobubble dynamics using both finite-element analysis and computational fluid dynamics, we quantified the cavitation-induced PA conversion efficiency of a water-immersed gold nanosphere, revealing new insights. Interestingly, sequential multi-bubble emission accompanied by high PA signal production occur under a single high-dose pulse of laser irradiation, enabling a cavitation-induced PA conversion efficiency up to 2%, which is -50 times higher than that due to thermal expansion. The cavitation-induced PA signal has unique frequency characteristics, which may be useful for a new approach for in vivo nanoparticle tracking. Our work offers theoretical guidance for accurate diagnosis and controllable therapy based on plasmon-mediated nanocavitation.

关键词： photoacoustic imaging conversion efficiency nanocavitation theranostics

Theoretical investigation on Raman induced Kerr effect spectroscopy in nonlinear confocal microscopy

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Science China(Physics,Mechanics & Astronomy) 2008年第7期51卷 788-796页

作者： GUO LiNa TANG ZhiLie xing da School of Physics and Telecommunication Engineering South China Normal UniversityGuangzhou 510006China Key Laboratory of Laser Life Science Ministry of Education of ChinaSouth China Normal UniversityGuangzhou 510631China

The imaging theory of Raman induced Kerr effect spectroscopy (RIKES) in nonlinear confocal microscopy is presented in this paper. Three-dimensional point spread function (3D-PSF) of RIKES nonlinear confocal microscopy in isotropic media is derived with Fourier imaging theory and RIKES theory. The impact of nonlinear property of RIKES on the spatial resolution and imaging properties of confocal microscopy have been analyzed in detail. It is proved that RIKES nonlinear confocal microscopy can simultaneously provide more information than two-photon confocal microscopy concerning molecular vibration mode, vibration orientation and optically induced molecular reorientation, etc. It is shown that RIKES nonlinear confocal microscopy significantly enhances the spatial resolution and imaging quality of confocal microscopy and achieves much higher resolution than that of two-photon confocal microscopy.

关键词： nonlinear confocal microscopy Raman induced Kerr effect spectroscopy three-dimensional point spread function

Synchronous detection of glutathione/hydrogen peroxide for monitoring redox status in vivo with a ratiometric upconverting nanoprobe

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Nano Research 2019年第4期12卷 931-938页

作者： Judun Zheng Yunxia Wu da xing Tao Zhang MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science South China Normal University Guangzhou 510631 China College of Biophotonics South China Normal University Guangzhou 510631 China

Cellular redox status presents broad implications with diverse physiological and pathological processes. Simultaneous detection of both the oxidative and reductive species of redox couples, especially the most representative pair glutathione/hydrogen peroxide (GSH/H2O2), is crucial to accurately map the cellular redox status. However, it still remains challenging to synchronously detect GSH/H2O2 in vivo due to lack of a reliable measuring tool. Herein, a ratiometric nanoprobe (UCNP-TB) possessing simultaneous delectability of GSH/H2O2 is established based on a multi-spectral upconverti ng nano phosphor (UCNP-OA) as the lumin esce nee res onance energy tran sfer (LRET) donor and two dye molecules as the acceptors, including a GSH-sensitive dye (TCG) and a H2O2-sensitive dye (BCH). With the as-prepared UCNP-TB, real-time and synchronous monitoring the variation of GSH and H2O2 in vitro and in living mice can be achieved using the ratio of the upcon versi on lumin esce nee (UCL) at 540 and 650 nm to that at 800 nm as the detecti on sign al, respectively, providi ng highly inhere nt reliability of the sensing results by self-calibrati on. Moreover, the nan oprobe is capable of mappi ng the redox status within the drug-resista nt tumor and the drug-induced hepatotoxic liver via ratiometric UCL imaging. Thus, this nan oprobe would provide a reliable tool to elucidate the redox state in vivo.

关键词： redox status glutathione hydrogen peroxide upconversion imaging nanoprobe

Thermally confined shell coating amplifies the photoacoustic conversion efficiency of nanoprobes

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Nano Research 2016年第12期9卷 3644-3655页

作者： Yujiao Shi Huan Qin Sihua Yang da xing Ministry of Education Key Laboratory of Laser Life Science and Institute of Laser Life Science College of Biophotonics South China Normal University Guangzhou 510631 China

Efficient probes/contrast agents are highly desirable for good-performance photoacoustic （PA） imaging, where the PA signal amplitude of a probe is dominated by both its optical absorption and the conversion efficiency from absorbed laser energy to acoustic waves. Nanoprobes have a unique micro- mechanism of PA energy conversion due to the size effect, which, however, has not been quantitatively demonstrated and effectively utilized. Here, we present quantitative simulations of the PA signal production process for plasmon- mediated nanoprobes based on the finite element analysis method, which were performed to provide a deep understanding of their PA conversion micromechanism. Moreover, we propose a method to amplify the PA conversion efficiency of nanoprobes through the use of thermally confined shell coating, which allows the active control of the conversion efficiency beyond that of conventional probes. Additionally, we deduced the dependence of the conversion efficiency on the shell properties. Gold-nanoparticles/polydimethylsiloxane nanocomposites were experimentally synthesized in the form of gel and microfilms to verify our idea and the simulation results agreed with the experiments. Our work paves the way for the rational design and optimization of nanoprobes with improved conversion efficiency.

关键词： photoacousticnanoprobes micromechanism conversion efficiency shell coating

Editorial—Introduction to the special issue on photoacoustic and microwave-thermoacoustic imaging

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Journal of Innovative Optical Health Sciences 2017年第4期10卷 1-3页

作者： da xing Sihua Yang MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science College of Biophotonics South China Normal University Guangzhou 510631 China

Photoacoustic imaging and microwave-thermoacoustic imaging are innovative hybrid imaging techniques that have experienced rapid development in recent *** imaging is based on the photoacoustic e®*** the laser pulses(the width of the laser pulse is usually several nanoseconds to tens of nanoseconds)irradiate the biological tissue,the absorbers in the tissue absorb the optical energy and then induce the instantaneous rise in temperature,and radiate the thermal energy in the form of mechanical energy,*** *** can detect the ultrasound signals with ultrasound transducer and recover the absorption information of the absorbers in the tissue with di®erent imaging *** imaging integrates the merit of high contrast of optical imaging and high imaging depth of ultrasound *** the excitation source of the photoacoustic imaging is changed into the microwave(the width of the microwave pulse is usually from tens of nanoseconds to hundreds of nanoseconds),that is called thermoacoustic imaging,which can provide high-resolution imaging and imaging depth of more than ten ***,photoacoustic imaging and thermoacoustic imaging have high molecular speci¯city and have already been widely used in the research of physics,chemistry,and biomedicine.

关键词： microwave pulse optical

Light-responsive charge-reversal nanovector for high-efficiency in vivo CRISPR/Cas9 gene editing with controllable location and time

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Nano Research 2020年第9期13卷 2399-2406页

作者： Yunxia Wu Judun Zheng Qin Zeng Tao Zhang da xing MOE Key Laboratory of Laser Life Science&Institute of Laser Life Science South China Normal UniversityGuangzhou 510631China Guangdong Provincial Key Laboratory of Laser Life Science College of BiophotonicsSouth China Normal UniversityGuangzhou 510631China

Controllably and efficaciously localized CRISPR/Cas9 plasmids transfection plays an essential role in genetic editing associated with various key human *** employed near-infrared(NIR)light-responsive CRISPR/Cas9 plasmids delivery via a charge-reversal nanovector to achieve highly efficient and site-specific gene *** nanovector with abundant positive charges was fabricated on the basis of an ultraviolet-sensitive conjugated polyelectrolyte coated on an upconversion nanomaterial(UCNP-UVP-P),which can convert into negative charges upon 980 nm light *** the as-prepared nanovector,we demonstrated the plasmids could be efficiency transfected into tumor cells(~63%±4%)in a time-contolled manner,and that functional CRISPR/Cas9 proteins could be successfully expressed in a selected NIR-irradiated ***,this strategy was successfully applied to the delivery of CRISPR/Cas9 gene to tumor cells in vivo,inducing high efficiency editing of the target gene PLK-1 under ***,this precisely controlled gene regulation strategy has the potential to serve as a new paradigm for gene engineering in complex biological systems.

关键词： light-responsive charge-reversal CRISPR/Cas9 gene editing

Aza-BODIPY-based phototheranostic nanoagent for tissue oxygen auto-adaptive photodynamic/photothermal complementary therapy

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Nano Research 2022年第1期15卷 716-727页

作者： Meijiao Zhao Qin Zeng Xipeng Li da xing Tao Zhang MOE Key Laboratory of Laser Life Science&Institute of Laser Life Science South China Normal UniversityGuangzhou 510631China Guangdong Provincial Key Laboratory of Laser Life Science College of BiophotonicsSouth China Normal UniversityGuangzhou 510631China

Tumor oxygen spatial heterogeneity is a critical challenge for the photodynamic inhibition of solid *** of an intelligent nanoagent to initiate optimal therapeutics according to the localized oxygen levels is an effective ***,we report an activatable nanoagent(BDP-Oxide nanoparticles(NPs))to enable the oxygen auto-adaptive photodynamic/photothermal complementaly *** the nanoagent accumulated in the tumor region,the low extracellular pH could trigger the disassociation of the nanoagent to release the phototheranostic agent,BDP-Oxide,which will subsequently afford the fluorescence imaging-guided photodynamic oxidation after it gets into the outer oxygen-rich *** with the penetration deepening in the solid tumor,furthermore,BDP-Oxide could be reduced into BDP by the cytochrome P450(CYP450)enzymes activated in the low oxygen tension regions of inner hypoxic tumors,which will switch on the photothermal and photoacoustic ***,the BDP-Oxide NPs-enabled photodynamic/photothermal complementary therapy significantly suppressed the solid tumor growth(inhibition rate of 94.8%).This work proposes an intelligent platform to address the oxygen partial pressure for the optimization of cancer phototherapeutics.

关键词： boron dipyrromethene(BODIPY) complementary therapy self-adaptive spatial heterogeneity of oxygen