外周血红细胞表面增强拉曼光谱对老年认知障碍的诊断价值

目的运用表面增强拉曼光谱(SERS)方法对患者外周血红细胞的拉曼光谱进行测量与分析,以探索其对不同认知功能状态老年认知障碍患者的诊断价值。方法选择上海市第六人民院老年病科住院的患者(年龄65岁)共62例,均行神经心理量表及临床评估,分为正常对照组、轻度认知障碍(MCI)组、痴呆(AD)组;同时记录基线数据。对红细胞进行SERS测量;运用五阶拟合等方法处理并提取样本拉曼光谱中的有效数据,线性判别法建立数据模型,受试者工作特征曲线检验诊断价值。结果 3组间红细胞SERS存在差异。由红细胞SERS数据得到的对照组与AD组判别模型可正确区分71.8%的病例,灵敏度和特异度分别为91.3%和56.2%;对照组与MCI组判别模型可正确区分58.7%的病例,灵敏度和特异度分别为56.5%和73.9%;AD组与MCI组判别模型可正确区分61.5%的病例,灵敏度和特异度分别为75.0%和65.2%。结论红细胞SERS数据在认知功能障碍诊断中有一定的价值,可能对研究AD红细胞病理生理变化有所启发。     

Hyphenation of Raman spectroscopy with gravimetric analysis to interrogate water-solid interactions in pharmaceutical systems

A moisture sorption gravimetric analyzer has been combined with a Raman spectrometer to better understand the various modes of water-solid interactions relevant to pharmaceutical systems. A commercial automated moisture sorption balance was modified to allow non-contact monitoring of the sample properties by interfacing a Raman probe with the sample holder. This hybrid instrument allows for gravimetric and spectroscopic changes to be monitored simultaneously. The utility of this instrument was demonstrated by investigating different types of water-solid interactions including stoichiometric and non-stoichiometric hydrate formation, deliquescence, amorphous-crystalline transformation, and capillary condensation. In each of the model systems, sulfaguanidine, cromolyn sodium, ranitidine HCl, amorphous sucrose and silica gel, spectroscopic changes were observed during the time course of the moisture sorption profile. Analysis of spectroscopic data provided information about the origin of the observed changes in moisture content as a function of relative humidity. Furthermore, multivariate data analysis techniques were employed as a means of processing the spectroscopic data. Principle components analysis was found to be useful to aid in data processing, handling and interpretation of the spectral changes that occurred during the time course of the moisture sorption profile.     

From the Cover: A [Cu2O]2+ core in Cu-ZSM-5, the active site in the oxidation of methane to methanol

Driven by the depletion of crude oil, the direct oxidation of methane to methanol has been of considerable interest. Promising low-temperature activity of an oxygen-activated zeolite, Cu-ZSM-5, has recently been reported in this selective oxidation and the active site in this reaction correlates with an absorption feature at 22,700 cm⁻¹. In the present study, this absorption band is used to selectively resonance enhance Raman vibrations of this active site. ¹⁸O₂ labeling experiments allow definitive assignment of the observed vibrations and exclude all previously characterized copper-oxygen species for the active site. In combination with DFT and normal coordinate analysis calculations, the oxygen activated Cu core is uniquely defined as a bent mono-(μ-oxo)dicupric site. Spectroscopically validated electronic structure calculations show polarization of the low-lying singly-occupied molecular orbital of the [Cu₂O]²⁺ core, which is directed into the zeolite channel, upon approach of CH₄. This induces significant oxyl character into the bridging O atom leading to a low transition state energy consistent with experiment and explains why the bent mono-(μ-oxo)dicupric core is highly activated for H atom abstraction from CH₄. The oxygen intermediate of Cu-ZSM-5 is now the most well defined species active in the methane monooxygenase reaction.     

Towards the development of a rapid,portable, surface enhanced Raman spectroscopy based cleaning verification system for the drug nelarabine

Objectives Cleaning verification is a scientific and economic problem for the pharmaceutical industry. A large amount of potential manufacturing time is lost to the process of cleaning verification. This involves the analysis of residues on spoiled manufacturing equipment, with high‐performance liquid chromatography (HPLC) being the predominantly employed analytical technique. The aim of this study was to develop a portable cleaning verification system for nelarabine using surface enhanced Raman spectroscopy (SERS). Methods SERS was conducted using a portable Raman spectrometer and a commercially available SERS substrate to develop a rapid and portable cleaning verification system for nelarabine. Samples of standard solutions and swab extracts were deposited onto the SERS active surfaces, allowed to dry and then subjected to spectroscopic analysis. Key findings Nelarabine was amenable to analysis by SERS and the necessary levels of sensitivity were achievable. It is possible to use this technology for a semi‐quantitative limits test. Replicate precision, however, was poor due to the heterogeneous drying pattern of nelarabine on the SERS active surface. Understanding and improving the drying process in order to produce a consistent SERS signal for quantitative analysis is desirable. Conclusions This work shows the potential application of SERS for cleaning verification analysis. SERS may not replace HPLC as the definitive analytical technique, but it could be used in conjunction with HPLC so that swabbing is only carried out once the portable SERS equipment has demonstrated that the manufacturing equipment is below the threshold contamination level.     

Mineralization of 3D Osteogenic Model Based on Gelatin-Dextran Hybrid Hydrogel Scaffold Bioengineered with Mesenchymal Stromal Cells: A Multiparametric Evaluation

Gelatin–dextran hydrogel scaffolds (G-PEG-Dx) were evaluated for their ability to activate the bone marrow human mesenchymal stromal cells (BM-hMSCs) towards mineralization. G-PEG-Dx1 and G-PEG-Dx2, with identical composition but different architecture, were seeded with BM-hMSCs in presence of fetal bovine serum or human platelet lysate (hPL) with or without osteogenic medium. G-PEG-Dx1, characterized by a lower degree of crosslinking and larger pores, was able to induce a better cell colonization than G-PEG-Dx2. At day 28, G-PEG-Dx2, with hPL and osteogenic factors, was more efficient than G-PEG-Dx1 in inducing mineralization. Scanning electron microscopy (SEM) and Raman spectroscopy showed that extracellular matrix produced by BM-hMSCs and calcium-positive mineralization were present along the backbone of the G-PEG-Dx2, even though it was colonized to a lesser degree by hMSCs than G-PEG-Dx1. These findings were confirmed by matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI), detecting distinct lipidomic signatures that were associated with the different degree of scaffold mineralization. Our data show that the architecture and morphology of G-PEG-Dx2 is determinant and better than that of G-PEG-Dx1 in promoting a faster mineralization, suggesting a more favorable and active role for improving bone repair.     

Synergistic effect between silver nanoparticles and antifungal agents on Candida albicans revealed by dynamic surface-enhanced Raman spectroscopy

Abstract

Identifying the mechanisms of action of new potential antibiotics is a necessary but time-consuming and costly process. We have developed an ultra-rapid, highly sensitive, and reproducible dynamic surface-enhanced Raman spectroscopy (D-SERS) method to discriminate and evaluate the sensitivity of Candida albicans to antifungal agents with different mechanisms by using silver nanoparticles (Ag NPs). Although Ag NPs have been used conventionally for the enhancement of Raman signals, the accompanying influence of Ag NPs on the microbes has not been investigated. Herein, surface charge and concentration of Ag NPs are likely to be the main influencing factors. Then different concentrations of Ag NPs with the same surface charge as C. albicans were prepared to find the optimal conditions for enhancement of Raman signals while minimally affecting tested fungi. Spectral variations were observed with increasing concentrations of Ag NPs, as well as those of antifungal agents, including echinocandin and azole drugs. The results indicated that the combination of sub-lethal Ag NPs and echinocandin drugs revealed potent synergistic effects against fungi. This could be explained by the metabolism of fungi, the result of which has also been verified by transmission electron microscopy (TEM). Lastly, the combination of sub-lethal Ag NPs and echinocandin drugs was used for a mammalian cell toxicity assay to demonstrate whether the optimal combination could cause lower cytotoxicity to mammalian cells. This work opens a window not only for the evaluation of antifungal agents with different mechanisms, but also for the clinical treatment of fungal infections or even new drug development.     

Effect of Desiccating Stress on Mouse Meibomian Gland Function

PurposeMice exposed to standardized desiccating environmental stress to induce dry eye-like symptoms have been used as a model to study the underlying mechanisms of evaporative dry eye. While studies have shown marked inflammatory and immune changes, the effect of such stress on meibomian gland function remains largely unknown. We sought to evaluate the effects of desiccating stress on meibocyte proliferation and meibum quality.MethodsTen mice were treated with scopolamine and subjected to a drafty low humidity environment (30-35%). Five and ten days after treatment, eyelids were harvested and cryosections stained with Ki67 antibody to identify cycling cells. Sections were also imaged using stimulated Raman scattering (SRS) microscopy to characterize the gland compositional changes by detecting the vibrational signatures of methylene (lipid) and amide-I (protein).ResultsDesiccating stress caused a 3-fold increase in basal acinar cell proliferation from 18.3 ± 11.1% in untreated mice to 64.4 ± 19.9% and 66.6 ± 13.4% after 5 and 10 days exposure, respectively (P < .001). In addition, SRS analysis showed a wider variation in the protein-to-lipid ratio throughout the gland, suggesting alterations in meibocyte differentiation and lipid synthesis.ConclusionsThese data are consistent with a model that a desiccating environment may have a direct effect on meibomian gland function, leading to a significant increase in basal acinar cell proliferation, abnormal meibocyte differentiation, and altered lipid production.     

Dispersion of Single‐Walled Carbon Nanotubes with Poly(Pyridinium Salt)s Containing Various Rigid Aromatic Moieties

Dispersions of single‐walled carbon nanotubes (SWNTs) with several poly(pyridinium salt)s containing various aromatic diamine moieties are prepared via a non‐covalent coagulation in DMSO. The interactions between SWNTs and polymers are characterized with various spectroscopic techniques. The ¹H NMR spectra suggest that strong interactions exist. The UV?Vis absorption spectra are independent of the incorporation of SWNTs. The resulting composites display high quenching efficiency in the photoluminescent properties; and transmission electron microscopy studies reveal the well‐dispersed SWNTs in the ionic polymer matrices. The enhanced thermal stability of the composites is determined by thermogravimetric analysis. The fully grown lyotropic LC properties of the poly(pyridinium salt)s are disrupted by the introduction of SWNTs.     

Standoff spectroscopy via remote generation of a backward-propagating laser beam

In an earlier publication we demonstrated that by using pairs of pulses of different colors (e.g., red and blue) it is possible to excite a dilute ensemble of molecules such that lasing and/or gain-swept superradiance is realized in a direction toward the observer. This approach is a conceptual step toward spectroscopic probing at a distance, also known as standoff spectroscopy. In the present paper, we propose a related but simpler approach on the basis of the backward-directed lasing in optically excited dominant constituents of plain air, N(2) and O(2). This technique relies on the remote generation of a weakly ionized plasma channel through filamentation of an ultraintense femtosecond laser pulse. Subsequent application of an energetic nanosecond pulse or series of pulses boosts the plasma density in the seed channel via avalanche ionization. Depending on the spectral and temporal content of the driving pulses, a transient population inversion is established in either nitrogen- or oxygen-ionized molecules, thus enabling a transient gain for an optical field propagating toward the observer. This technique results in the generation of a strong, coherent, counterpropagating optical probe pulse. Such a probe, combined with a wavelength-tunable laser signal(s) propagating in the forward direction, provides a tool for various remote-sensing applications. The proposed technique can be enhanced by combining it with the gain-swept excitation approach as well as with beam shaping and adaptive optics techniques.