药物辅料中有毒掺杂物的拉曼/近红外光谱法检测灵敏度评价

目的 建立常用药物辅料(甘油)中有毒掺杂物(二甘醇)的快速检测方法。 方法 利用拉曼/近红外光谱法结合移动窗口相关系数法评价有毒掺杂物的检测灵敏度。 结果 拉曼光谱下获得的检测灵敏度优于近红外光谱,同时移动窗口法可进一步提高检测灵敏度。 结论 拉曼光谱法有望成为现场快速检测药物辅料中掺杂有毒物质的有效方法。     

拉曼光谱法用于药品注射液标准中鉴别项的探讨

目的:探讨在药品标准中采用拉曼光谱方法作为注射液鉴别项的科学性、可行性和有效性。方法:采用拉曼光谱法,以相应对照品的水溶液的拉曼光谱作为参考光谱,对《中国药典》2010年版二部中采用红外光谱法鉴别的8个注射液品种进行定性鉴别。结果:拉曼光谱法能够对氨茶碱注射液等8个品种进行鉴别。结论:拉曼光谱法用于注射液品种的定性鉴别,具有不需要复杂的样品前处理,可直接测定,准确度高,不受水分干扰等优点,可作为药品标准中一些注射液及其他溶液制剂定性鉴别的方法之一。     

拉曼光谱技术在癌症诊断中的研究进展

癌症是世界上发病率和病死率最高的疾病之一,随着生活方式的变化和社会老龄化,防治癌症的任务将十分艰巨。早期诊断方法存在阳性率低、过度诊断及有创等缺点,不利于高危人群筛查及癌症生存率的提高。拉曼光谱技术可以提供检测样本的分子结构特征,适合于癌症的早期诊断,且具有快速、无创及高灵敏度的特点,正在成为一种新的癌症诊断方法。通过介绍国内外拉曼光谱技术在癌症诊断方面的研究进展,提出采用唾液表面增强拉曼检测技术为癌症的筛查和早期诊断提供新途径的发展思路。     

An update on the use of Raman spectroscopy in molecular cancer diagnostics: current challenges and further prospects

Introduction: Cancer is responsible for an extraordinary burden of disease, affecting 90.5 million people worldwide in 2015. Outcomes for these patients are improved when the disease is diagnosed at an early, or even precancerous, stage. Raman spectroscopy is demonstrating results that show its ability to detect the molecular changes that are diagnostic of precancerous and cancerous tissue. This review highlights the new advances occurring in this domain.

Areas covered: PubMed searches were undertaken to identify new research in the utilisation of Raman spectroscopy in cancer diagnostics. The areas in which Raman spectroscopy is showing promise are covered, including improving the accuracy of identifying precancerous changes, using the technology in real time, in vivo modalities, the search for a biomarker to aid potential screening and predicting the response of the cancer to the treatment regimen.

Expert commentary: Many of the examples in this review are focused on Barrett’s oesophagus and oesophageal adenocarcinoma as this is my area of expertise and perfectly exemplifies where Raman spectroscopy could be utilised in clinical practise. The authors discuss the areas where they believe current knowledge is lacking and how Raman spectroscopy could answer the dilemmas that are still faced in the management of cancer.     

Label-free DNA imaging in vivo with stimulated Raman scattering microscopy

Label-free DNA imaging is highly desirable in biology and medicine to perform live imaging without affecting cell function and to obtain instant histological tissue examination during surgical procedures. Here we show a label-free DNA imaging method with stimulated Raman scattering (SRS) microscopy for visualization of the cell nuclei in live animals and intact fresh human tissues with subcellular resolution. Relying on the distinct Raman spectral features of the carbon-hydrogen bonds in DNA, the distribution of DNA is retrieved from the strong background of proteins and lipids by linear decomposition of SRS images at three optimally selected Raman shifts. Based on changes on DNA condensation in the nucleus, we were able to capture chromosome dynamics during cell division both in vitro and in vivo. We tracked mouse skin cell proliferation, induced by drug treatment, through in vivo counting of the mitotic rate. Furthermore, we demonstrated a label-free histology method for human skin cancer diagnosis that provides comparable results to other conventional tissue staining methods such as H&E. Our approach exhibits higher sensitivity than SRS imaging of DNA in the fingerprint spectral region. Compared with spontaneous Raman imaging of DNA, our approach is three orders of magnitude faster, allowing both chromatin dynamic studies and label-free optical histology in real time.In vivo imaging of chromatin or chromosome structures and dynamics during vital cellular processes, such as cell division, differentiation, apoptosis, and carcinogenesis, generally relies on the use of either exogenous or endogenous fluorescent labels, the latter of which often involves complicated transgenic organisms (1, 2). A label-free approach, however, allows the visualization of these processes in a noninvasive way in live organisms. In medicine, visualization of nuclear morphology, architecture, size, shape, and mitotic figures provide the most important cytologic features for rendering histologic diagnosis (3, 4). Conventional histology is heavily reliant on tissue biopsies and staining (such as H&E or immunohistochemistry), whereas label-free imaging is able to reveal similar information as that from the stained tissue, and in addition, it allows for a noninvasive characterization and diagnosis of human tissue in real time in vivo.Stimulated Raman scattering (SRS) microscopy offers a contrast mechanism based on Raman spectroscopy, probing the intrinsic vibrational frequencies of chemical bonds or groups (5–8). In SRS microscopy, the collinear pump and Stokes laser beams, at frequencies of ω_p and ω_s, respectively, are tightly focused onto the sample (Fig. 1A). When the frequency difference, ω_p − ω_s, matches a Raman-active molecular vibration, the SRS signal (attenuation to the pump beam or increase on the Stokes beam) is generated through a nonlinear process similar to the stimulated emission. With a highly sensitive detection scheme, involving megahertz modulation transfer, SRS microscopy exhibits orders of magnitude of shorter acquisition time than conventional Raman microscopy (5). Being a nonlinear optical microscopy, it offers 3D sectioning capability with a diffraction-limited spatial resolution. SRS microscopy has been extensively applied to image biomolecules in cells and tissues (9–15).Open in a separate windowFig. 1.Label-free SRS imaging of DNA (magenta), protein (blue), and lipids (green) in live cells. SRS images at three selected Raman shifts in the CH stretching vibrational band were acquired. Linear decomposition was performed with a premeasured calibration matrix to retrieve the distribution of DNA, protein, and lipids. (A) Setup of the SRS microscopy, capable of automatically acquiring images at multiple Raman shifts. This was achieved by synchronizing the tuning of the laser frequency (Lyot filter) to the imaging frame trigger of the microscope. (Inset) Time-lapse images of a HeLa cell undergoing cell division (Movie S1). (B) Raman spectra of DNA, cellular protein, and cellular lipids extracted from HeLa cells. (C) Raman spectrum of the cell pellet. Linear fitting demonstrated that the three compounds in B accounted for ∼90% of the total CH stretching vibration of the cells. (D) SRS images of a live cell in mitotic phase (prophase) at 2,967, 2,926, and 2,850 cm⁻¹, respectively, and the decomposed distribution of DNA, protein, lipids, and the overlay. Chromosomes were visualized with both high contrast and high signal-to-noise ratio. (E) SRS images of a live cell in interphase and the decomposed distribution of DNA, protein, lipids, and the overlay. Detailed internal nuclear features were revealed clearly. (F) Images with SRS and TPEF of a mitotic cell stained with DRAQ5, correlated very well with each other. (Scale bar, 10 μm.)SRS imaging was initially carried out at one Raman shift at a time (5). Recent developments on multiplex detection allow for distinguishing various chemical species with overlapping Raman bands by either broadband excitation (16, 17) or narrowband scanning (18, 19). SRS at two specific Raman shifts within the broadband of the carbon-hydrogen (CH) stretching vibrational mode (2,800–3,050 cm⁻¹) has been used to simultaneously map protein and lipid distribution in cells and tissues (20, 21). In particular, protein and lipid imaging has been applied to delineate brain tumor margins, providing images similar to conventional H&E staining (11). However, SRS does not offer detailed nuclear morphology and architecture, compared with the conventional histology, due to the lack of imaging contrast for DNA.SRS has been demonstrated to be valuable for DNA imaging in cultured cells based on detection of the phosphate peaks within the fingerprint spectral region (22). However, imaging of DNA in this spectral region is difficult for cells in interphase because of the lower DNA density, especially in live tissue. This challenge is also the case for spontaneous Raman imaging (SI Text) (23).Here we demonstrate that, relying on the unique and distinct spectral features of DNA in the CH stretching vibrational region (the high wavenumber range), the distribution of DNA, together with those of protein and lipids, can be mapped by the linear decomposition of images at three optimally selected Raman shifts. This approach offers much higher sensitivity than that of DNA imaging in the fingerprint region, making dynamic imaging of DNA feasible for both mitotic phase and interphase cells in vitro and in vivo.     

Orientation Dependence of Cathodoluminescence and Photoluminescence Spectroscopy of Defects in Chemical-Vapor-Deposited Diamond Microcrystal

Point defects, impurities, and defect–impurity complexes in diamond microcrystals were studied with the cathodoluminescence (CL) spectroscopy in the scanning electron microscope, photoluminescence (PL), and Raman spectroscopy (RS). Such defects can influence the directions that microcrystals are grown. Micro-diamonds were obtained by a hot-filament chemical vapor deposition (HF CVD) technique from the methane–hydrogen gas mixture. The CL spectra of diamond microcrystals taken from (100) and (111) crystallographic planes were compared to the CL spectrum of a (100) oriented Element Six diamond monocrystal. The following color centers were identified: 2.52, 2.156, 2.055 eV attributed to a nitrogen–vacancy complex and a violet-emitting center (A-band) observed at 2.82 eV associated with dislocation line defects, whose atomic structure is still under discussion. The Raman studies showed that the planes (111) are more defective in comparison to (100) planes. What is reflected in the CL spectra as (111) shows a strong band in the UV region (2.815 eV) which is not observed in the case of the (100) plane.     

Temperature-Dependent Raman Spectroscopic Study of the Double Molybdate KBi(MoO4)2

In situ high-temperature Raman spectra of polycrystalline KBi(MoO₄)₂ were recorded from room temperature to 1073 K. Thermal stability of the monoclinic KBi(MoO₄)₂ was examined by temperature-dependent XRD. The monoclinic phase transformed into the scheelite tetragonal structure at 833 K, and then to the monoclinic phase at 773 K. Quantum chemistry ab initio calculation was performed to simulate the Raman spectra of the structure of KBi(MoO₄)₂ high-temperature melt. The experimental Raman band at 1023 K was deconvoluted into seven Gaussian peaks, and the calculated results were in good agreement with the experimental data. Therefore, the vibrational modes of Raman peaks of molten KBi(MoO₄)₂ were assigned. It was confirmed that the isolated structure of [Bi(MoO₄)₂]⁻ monomer, consisting of Mo⁶⁺ centers and Bi³⁺ sub-centers connected by edge-sharing, mainly exists in the melt of KBi(MoO₄)₂.