QEPAS系统中石英音叉模态仿真计算与研究

对石英音叉增强型光声光谱(QEPAS)系统中常用的石英音叉进行了有限元模态计算，获得石英音叉前6阶振型与模态频率，认知了第4阶对称摆动振型为有效振动，利用单因素法分析了石英音叉的音臂长度l₁、音臂宽度w₁、音臂厚度t、音臂切角θ、音臂圆孔直径d及音臂圆孔高度h对低阶有效共振频率(Fre)的影响，敏感度依次为： l₁> w₁>d>θ>t>h，考虑实际设计情形，筛选出了l₁，w₁，d与h四个石英音叉设计变量，采用Box-Behnken实验设计方案与RSM(response surface methodology)方法，以Fre为函数目标，建立l₁，w₁，d与h的二次回归响应面模型，得到了参数之间的交互作用，利用Design-Expert软件对响应面模型进行设计参数反求，结果表明，在15 000 Hz≤Fre≤25 000 Hz计算区域内误差较小，基本满足QEPAS系统的计算需求，所提出的研究与设计方法具有一定通用性，可为QEPAS系统中石英音叉结构参数设计提供参考。     

Xanthene-Based Nitric Oxide-Responsive Nanosensor for Photoacoustic Imaging in the SWIR Window

Shortwave infrared (SWIR) dyes are characterized by their ability to absorb light from 900 to 1400 nm, which is ideal for deep tissue imaging owing to minimized light scattering and interference from endogenous pigments. An approach to access such molecules is to tune the photophysical properties of known near-infrared dyes. Herein, we report the development of a series of easily accessible (three steps) SWIR xanthene dyes based on a dibenzazepine donor conjugated to thiophene ( SCR-1 ), thienothiophene ( SCR-2 ), or bithiophene ( SCR-3 ). We leverage the fact that SCR-1 undergoes a bathochromic shift when aggregated for in vivo studies by developing a ratiometric nanoparticle for NO ( rNP-NO ), which we employed to successfully visualize pathological levels of nitric oxide in a drug-induced liver injury model via deep tissue SWIR photoacoustic (PA) imaging. Our work demonstrates how easily this dye series can be utilized as a component in nanosensor designs for imaging studies.     

Nanostructure-Driven Indocyanine Green Dimerization Generates Ultra-Stable Phototheranostics Nanoparticles

Indocyanine green (ICG) is the only near-infrared (NIR) dye approved for clinical use. Despite its versatility in photonic applications and potential for photothermal therapy, its photobleaching hinders its application. Here we discovered a nanostructure of dimeric ICG (Nano-dICG) generated by using ICG to stabilize nanoemulsions, after which ICG enabled complete dimerization on the nanoemulsion shell, followed by J-aggregation of ICG-dimer, resulting in a narrow, red-shifted (780 nm→894 nm) and intense (≈2-fold) absorbance. Compared to ICG, Nano-dICG demonstrated superior photothermal conversion (2-fold higher), significantly reduced photodegradation (−9.6 % vs. −46.3 %), and undiminished photothermal effect (7 vs. 2 cycles) under repeated irradiations, in addition to excellent colloidal and structural stabilities. Following intravenous injection, Nano-dICG enabled real-time tracking of its delivery to mouse tumors within 24 h by photoacoustic imaging at NIR wavelength (890 nm) distinct from the endogenous signal to guide effective photothermal therapy. The unprecedented finding of nanostructure-driven ICG dimerization leads to an ultra-stable phototheranostic platform.     

Localized surface plasmon resonance properties and biomedical applications of copper selenide nanomaterials

Nanomaterials with localized surface plasmon resonance (LSPR) locating in the near-infrared region have broad application prospects in the field of biomedicine. However, the biggest problem that limits the biomedical application of such nanomaterials lies in two aspects: First, the potential long-term in vivo toxicity caused by the metabolism of many nanomaterials with LSPR effect; Second, most of current nanomaterials with LSPR effect are difficult to achieve LSPR wavelength tunability in the near-infrared region to adapt to different biomedical applications. Copper selenide nanomaterials are composed of selenium and copper, which are necessary nutrient elements for human life. Because of the active and flexible chemical properties of selenium and copper, copper selenide nanomaterials can not only be effectively degraded and utilized in human body, but also be endowed with various physicochemical properties by chemical modification or doping. Recently, copper selenide nanomaterials have shown unique properties such as LSPR in the near-infrared region, making them attractive for near-infrared thermal ablation, photoacoustic imaging, disease marker detection, multimode imaging, and so on. Currently, to the best of our knowledge, there is no review on the LSPR properties of copper selenide nanomaterials and its biomedical applications. This review first discusses the relationship between the physicochemical properties and the LSPR of copper selenide nanomaterials and then summarizes the latest progress in the application of copper selenide nanomaterials in biological detection, diagnosis, and treatment of diseases. In addition, the advantages, and prospects of copper selenide nanomaterials in biomedicine are also highlighted.     

圆柱形光声池结构及环境因素对声学本征频率的影响

以典型的圆柱形光声池为研究对象,建立光声池声学仿真有限元模型,并在此基础上,研究了光声池中谐振腔、缓冲腔、进出气孔结构参数以及温度、湿度因素对其声学本征频率的影响规律.研究结果表明:圆柱形光声池的进、出口孔对其声学本征频率影响极不敏感,设计计算中可以忽略不计,谐振腔的长度影响最为敏感,其次为谐振腔的直径.此外缓冲腔的长度与直径对其亦有一定影响,因而在准确计算时需要加以考虑.温度与湿度对光声池声学本征频率的影响均呈现正线性增长规律,温度的影响随着谐振腔长度的增大而减小,湿度的影响随着温度的升高而增大,仅计算光声池的声学本征频率时,湿度的影响在室温环境下且湿度变动较小的条件下可以忽略.     

Recent Progress on Infrared Photoacoustic Spectroscopy Techniques

Abstract

Analogous to most new methods in science, photoacoustic spectroscopy (PAS) grew out of an advance in technology, in this case the dramatic improvement in novel light sources, modulators, and acoustic detectors, as well as signal recovery electronics, which in turn was made possible by the development of modern PAS techniques. PAS is a promising technique that can be used to analyze and characterize a broad variety of objects (gaseous, solid, and liquid samples). In the present review, the recent development of infrared PAS limited to the general area of gas-phase analysis techniques since 1990 is summarized, with special emphasis on the development of new or enhanced analytical methodologies based on the use of the photoacoustic (PA) effect to improve the sensitivity of PAS by enhancing signal or reducing noise levels, with regard to PA systems, applications, and conclusions. The applications of these novel PA methods are mainly concerned with molecular spectroscopic, industrial, atmospheric, environmental, chemical and biological, and medical and clinical analysis. New prospects and challenges in various application fields of PAS technique are described.     

A Study on Photoacoustic Phase Spectra of Rare Earth Complexes with Oxine

Photoacoustic phase is the time delay that occurs from light to acoustic signal. the phase includes two components: one is the time delay that occurs during the process in which light absorbed by a sample converts into heat; the other is the time delay caused from heat to acoustic signal. a modified formula of PA phase is presented based on the R-G theory considering the phase caused by non-radiative relaxation processes. the phase is associated with absorption coefficient (β), thermal diffusion length of sample (μ_s), the longest lifetime of all excited states (r), and the ratio of rapid to slow heat component (R). When the photoacoustic signal is saturated the phase is associated with only T and R. the effect of different rare earth ions on the PA phase spectra of the ligand (oxine) in the rare earth complexes are reported and are well explained by using the phase formula of PA saturation.     

Vibrational spectroscopy in the development of surface hydrophilic elastomer latex (SHEL)

An illustrative example is given to show how various vibrational spectroscopy techniques coupled with two-dimensional (2D) correlation analysis can be effectively utilized in the development of a novel and functional material. Surface-hydrophilic elastomer latex (SHEL) is a material exhibiting rather unusual permanently water-wettable surface feature despite having a soft and rubbery bulk property, which can be successfully analyzed with vibrational spectroscopy. 2D photoacoustic (PAS) IR spectra of a SHEL film indicate the localized surface segregation of long-chain ethoxylate moiety of the oligomeric surfactant used in the preparation of this material. The accumulation of the hydrophilic long-chain ethoxylate produces the high energy polar surface over the hydrophobic bulk phase of SBR copolymer. The persistence of very low water contact angle, even after repeated washing of a SHEL film with an excess amount of water, indicates permanent covalent attachment of long-chain ethoxylate group to the SBR copolymer. 2D Raman spectra generated from the process monitoring of the emulsion copolymerization of SHEL reveal the mechanism of the covalent attachment of long-chain ethoxylate. The reaction involves a separate step of oleyl moiety of the block surfactant reacting with 1,3-butadiene prior to the onset of copolymerization to produce the SBR latex product.     

An Overview of The Photoacoustic Phase Spectra of Rare Earth Complexes

Abstract

The photoacoustic(PA) amplitude and phase spectra of several kinds of rare earth (RE) complexes are reported and summarized briefly. It is observed that both the amplitude and phase spectra well characterize the different energy levels of the RE complexes. The phase angle of the RE complexes is associated with the relaxation time τ and the optical absorption coefficient β concerning with the π-π? transition and the f-f transitions, respectively. After individual detailed discussion of the phase spectra, a reasonable theoretical consideration is given to interpret the results.     

Evaluation of radiation damage behavior in polyimide aerogel by infrared camera and photoacoustic spectroscopy

In this work, the optical absorption and thermal properties of polyimide aerogel have been investigated by Infrared Camera, ultraviolet–visible and photoacoustic spectroscopy under low energy proton irradiation. The characterization method of the infrared camera can obtain the optical absorption ratio, and meanwhile get the information of specific heat capacity. Moreover, it can acquire the nature information of damaged area rather than the overall performance. The results show an increase in optical absorption after proton irradiation, which is in good coincidence with Ultraviolet–visible spectroscopy analysis. And the specific heat capacity decreased linearly with proton fluences, which can be attributed to the irradiation damage and carbonization in polyimide aerogel. The Raman spectra suggested the cleavage of chemical bonds and carbonization in polyimide aerogel. This work provides the novel, non-destructive and sensitive methods to characterize irradiation damage of aerogel.