糖脂功能化聚二乙炔Langmuir-Schaefer薄膜与大肠杆菌的分子识别及动力学过程研究

在气液界面上研究了α-D-甘露糖苷-十六烷(MC₁₆)与10,12-二十五碳双炔酸混合单分子膜行为,二者具有较好的互溶性.在疏水的玻璃衬底上用Langmuir-Schaefer(LS)薄膜技术制备单层MC₁₆/PDA薄膜,研究了这种仿生薄膜与大肠杆菌jm109的相互作用.大肠杆菌jm109对MC₁₆修饰的聚二乙炔LS薄膜的吸附,使薄膜颜色由蓝色变为红色,用紫外-可见吸收光谱可进行定量检测.动力学研究显示比色响应值随时间的增加而增加,3min内即有显著变化,15min后趋于饱和,20min后CR值达到28%,进一步探讨了分子识别的动力学过程.     

基于新型可视化学传感阵列的氨基酸快速识别

以卟啉和其衍生物及指示剂为传感元件,构建了一种对氨基酸敏感的可视传感阵列.可视化学传感阵列以交互响应的敏感元件组成阵列,对不同物质产生特异的响应,并通过信号识别处理系统,将检测结果以图谱的方式显示,实现检测的可视化.研究中筛选了对氨基酸敏感的36种化学物质,构建了6×6的传感阵列,使用自主研发的阵列数据采集与处理系统,对10种具有代表性的常见氨基酸进行了检测,氨基酸溶液与阵列的反应时间为5 min.对实验检测结果数据采用主成分分析和判别分析进行了计算和分析.实验结果显示,通过阵列响应的可视差图可以将浓度为375 μmol/L的10种氨基酸明显区分.判别分析结果显示,本可视阵列对氨基酸识别的准确率达到97%.二维主成分散点图和判别分析散点图对10种氨基酸都有显著分辨效果.本可视传感阵列可用于氨基酸的快速识别.     

聚苯胺薄膜的溶液表面制备及室温氨气气敏性能

提出了一种基于溶液表面的聚苯胺(PANI)薄膜及气敏器件的室温制备方法,以苯胺单体、盐酸和过硫酸铵为原料通过氧化聚合在其水溶液表面直接获得质子化聚苯胺(PANI)薄膜,并利用薄膜的可转移特性构筑气敏器件.研究发现溶液的pH对PANI致密薄膜的形成至关重要,从而提出了质子化苯胺单体优先在溶液表面聚集和聚合的PANI薄膜形成机制.该薄膜气敏器件能够对NH₃进行有效的室温检测,且性能随薄膜聚合温度和聚合时间的变化呈规律性变化,优选制备条件下(pH=0.6,室温18℃,聚合60 min)的薄膜其检测下限为10^-6,响应与NH₃浓度呈良好的线性关系,并具有良好的重复性、选择性、快速响应和有竞争力的响应值.该薄膜制备工艺体现了“绿色”制备思想,且薄膜能够大面积制备并具有优异的气敏性能,有望为PANI-基薄膜的制备与室温气体传感器的研究与应用提供一种新的思路.     

LDHs薄膜基纳米荧光传感器的制备及其研究进展

层状复合氢氧化物(LDHs)是一种层板金属元素和层间离子可调的无机层状材料,利用其独特的插层组装特性,基于静电、氢键、范德华力等相互作用力,功能性荧光客体分子可与LDHs纳米片复合构筑多功能荧光薄膜材料.LDHs薄膜基荧光材料用于荧光传感器,在有机挥发性气体(VOCs)、温度、压力、重要生物分子等的检测中显示了良好性能.本文总结了LDHs复合薄膜的制备方法以及近年来其在纳米荧光传感领域的进展,并对其未来发展做出了展望.     

薄膜基荧光传感检测的研究进展

薄膜基荧光传感器是继离子迁移谱之后,业界公认的一种最具发展潜力的微痕量物质探测技术.由于其具有灵敏性、便携性、实时检测、响应速度快、易于制造、不污染待测体系等优点,在食品检测、环境监测、质量控制和生物医学分析等领域引起了广泛的关注和研究.本文主要综述了近年来薄膜基荧光传感在挥发性气体检测、有毒化学品检测、爆炸物检测、溶液相离子检测以及生物监测等领域的研究进展,并提出了薄膜基荧光传感所面临的挑战与未来的发展方向.     

分子印迹光子晶体凝胶传感器检测食品中的着色剂姜黄素

开发一种分子印迹光子晶体凝胶传感器,用于快速检测食品中的着色剂姜黄素。以聚苯乙烯微球阵列为模板,姜黄素为印迹分子,借助"三明治"结构,热引发聚合后除去模板和印迹分子,制备具有良好光学性质的传感器,通过红外光谱、扫描电镜对其进行表征,考察其响应性、平衡时间、选择性等,再利用该传感器检测实际样品中的姜黄素含量。结果表明:该传感器具有相互贯通的三维有序大孔结构;当姜黄素浓度增加到0. 12 mmol/L时,吸收峰位移变化最大为97 nm,并伴有明显的颜色变化。方法用于姜黄素分析,检出限为0. 57μmol/L;响应时间50 s。本方法用于小米和果冻中姜黄素的检测,回收率分别为94. 4%和87. 1%,为复杂样品中的姜黄素检测提供了一种可能的途径。     

基于有机纳米纤维薄膜的荧光化学传感

薄膜荧光化学传感提供了一种固相、便携、易操作的气相分子检测技术,在环境、安全、生物医学、健康监测等领域具有重要的应用价值和发展前景.基于本课题组在超分子自组装构建n-型有机半导体苝二酰亚胺衍生物(PTCDI)一维纳米纤维及其荧光薄膜检测胺类等气相分子领域研究,结合其他课题组工作,本文阐述了该类纳米纤维多孔薄膜在结构调控,荧光传感应用性能、机制和意义方面的研究进展.同时,也介绍了本课题组在p型有机半导体咔唑角亚乙炔四环(ACTC)和咔唑三聚体等在本领域的进展,最后对未来挑战和发展方向进行了展望.     

MB-硬脂酸复合薄膜光波导传感器检测氯化氢气体

利用旋转甩涂法将亚甲基蓝(MB)掺杂的硬脂酸溶液涂成薄膜固定在钾离子(K⁺)交换玻璃光波导表面上, 研制了MB-硬脂酸复合薄膜/K⁺交换玻璃光波导传感器, 并对酸性气体进行了检测. 该复合薄膜与氯化氢(HCl)气体作用时, 薄膜颜色从深蓝色变为浅蓝色, 导致薄膜对倏逝波的吸收降低, 使传感器的输出光强度增强. 结果表明, 在室温下该传感器对低浓度的氯化氢气体仍具有较好的重复性和选择性响应, 可检测到体积分数为1×10^-6%的HCl气体, 响应和恢复时间分别为7和20 s, 相对标准偏差为±6.06%. 该传感器具有灵敏度高、 响应-恢复速度快、 可逆性好、 成本低和容易制备等特点.     

基于天然气敏材料猪肉中优势腐败菌的可视化检测

优势致腐菌是引起猪肉变质的重要原因之一,为了探索猪肉优势致腐菌绿色、快速的检测方法,本研究使用天然色素作为气体可视化传感器阵列的气敏材料,区分猪肉中的优势致腐菌。首先从植物中提取17种天然色素作为气敏材料,并将其固定在基底材料上,干燥后制成气体可视化传感器阵列。将3种优势致腐菌(梭状芽孢杆菌、热死环丝菌、假单胞菌)分别接种至3组猪肉样本中,在室温(20℃)条件下分别培养8、16和24 h,然后将传感器阵列与猪肉样本产生的挥发性物质接触并发生反应,用扫描仪获取传感器阵列与每个样本反应前后的图像信息,将传感器反应前后的颜色差值作为样本的特征值组成一个数据矩阵,并制成差值图像。最后采用主成分分析对培养8,16和24 h后的3种优势致腐菌进行检测,识别率分别为90%,90%和100%。结果表明,天然色素可以作为气体传感器的气敏材料,检测猪肉的优势致腐菌,且检测过程不会产生化学毒害。     

呼吸图法制备基于准聚轮烷的响应性薄膜

响应性薄膜能够响应外界的刺激来改变自身的结构或性能, 是智能材料的重要组成部分. 本工作以1,4-二乙氧基柱[5]芳烃(1,4-diethoxypillar[5]arene, DEP5A)和聚己内酯-b-聚乙二醇-b-聚己内酯(PCL-b-PEG-b-PCL)构建的准聚轮烷(polypseudorotaxane, PPR)为原料, 利用呼吸图法制备出了蜂窝状多孔及球状组装体的疏水薄膜. 研究发现溶剂、浓度、柱芳烃物质的量比和成膜气氛等因素对薄膜表面形貌均能产生较大的影响. 通过制膜条件的优化, 在水汽氛围中制备出了表面具有规则蜂窝状结构的多孔薄膜, 在乙醇氛围下制备出了表面为规整的褶皱球状组装体的薄膜. 研究表明, 上述两种具有规则表面形貌的PPR薄膜对竞争性客体1,4-二溴丁烷都具有响应性, 表现出薄膜表面形貌的变化及亲疏水性的变化. 此类响应性薄膜在微量液体无损转移、功能性涂层和智能薄膜等方面具有潜在的应用前景.     

Volatile Organic Compound Based Probe for Induced Volatolomics of Cancers

The development of efficient protocols for cancer diagnosis remains highly challenging. An emerging approach relies on the detection in exhaled breath of volatile organic compounds (VOC) produced by tumours. In this context, described here is a novel strategy in which a VOC‐based probe is converted selectively in malignant tissues, by a tumour‐associated enzyme, for releasing the corresponding VOC. The latter is then detected in the exhaled breath as a tumour marker for cancer diagnosis. This approach allows the detection of several different tumours in mice, the monitoring of tumour growth and tumour response to chemotherapy. Thus, the concept of “induced volatolomics” provides a new way to explore biological processes using VOC‐based probes that could be adapted to many biomedical applications.     

Human breath analysis: methods for sample collection and reduction of localized background effects

Solid-phase microextraction (SPME) was applied, in conjunction with gas chromatography–mass spectrometry, to the analysis of volatile organic compounds (VOCs) in human breath samples without requiring exhaled breath condensate collection. A new procedure, exhaled breath vapor (EBV) collection, involving the active sampling and preconcentration of a breath sample with a SPME fiber fitted inside a modified commercial breath-collection device, the RTube™, is described. Immediately after sample collection, compounds are desorbed from the SPME fiber at 250 °C in the GC-MS injector. Experiments were performed using EBV collected at −80 °C and at room temperature, and the results compared to the traditional method of collecting exhaled breath condensate at −80 °C followed by passive SPME sampling of the collected condensate. Methods are compared in terms of portability, ease-of-use, speed of analysis, and detection limits. The need for a clean air supply for the study subjects is demonstrated using several localized sources of VOC contaminants including nail polish, lemonade, and gasoline. Various simple methods to supply clean inhaled air to a subject are presented. Chemical exposures are used to demonstrate the importance of providing cleaned air (organic vapor respirator) or an external air source (tubing stretched to a separate room). These techniques allow for facile data interpretation by minimizing background contaminants. It is demonstrated herein that this active SPME breath-sampling device provides advantages in the forms of faster sample collection and data analysis, apparatus portability and avoidance of power or cooling requirements, and performance for sample collection in a contaminated environment.      

Breathing Rhythm Variations during Wash-In Do Not Influence Exhaled Volatile Organic Compound Profile Analyzed by an Electronic Nose

E-noses are innovative tools used for exhaled volatile organic compound (VOC) analysis, which have shown their potential in several diseases. Before obtaining a full validation of these instruments in clinical settings, a number of methodological issues still have to be established. We aimed to assess whether variations in breathing rhythm during wash-in with VOC-filtered air before exhaled air collection reflect changes in the exhaled VOC profile when analyzed by an e-nose (Cyranose 320). We enrolled 20 normal subjects and randomly collected their exhaled breath at three different breathing rhythms during wash-in: (a) normal rhythm (respiratory rate (RR) between 12 and 18/min), (b) fast rhythm (RR > 25/min) and (c) slow rhythm (RR < 10/min). Exhaled breath was collected by a previously validated method (Dragonieri et al., J. Bras. Pneumol. 2016) and analyzed by the e-nose. Using principal component analysis (PCA), no significant variations in the exhaled VOC profile were shown among the three breathing rhythms. Subsequent linear discriminant analysis (LDA) confirmed the above findings, with a cross-validated accuracy of 45% (p = ns). We concluded that the exhaled VOC profile, analyzed by an e-nose, is not influenced by variations in breathing rhythm during wash-in.     

Electrospun polystyrene/graphene nanofiber film as a novel adsorbent of thin film microextraction for extraction of aldehydes in human exhaled breath condensates

In the current study, we introduced a novel polystyrene/graphene (PS/G) composite nanofiber film for thin film microextraction (TFME) for the first time. The PS/G nanofiber film was fabricated on the surface of filter paper by a facile electrospinning method. The morphology and extraction performance of the resultant composite film were investigated systematically. The PS/G nanofiber film exhibited porous fibrous structure, large surface area and strong hydrophobicity. A new thin film microextraction-high performance liquid chromatography (TFME-HPLC) method was developed for the determination of six aldehydes in human exhaled breath condensates. The method showed high enrichment efficiency and fast analysis speed. Under the optimal conditions, the linear ranges of the analytes were in the range of 0.02–30 μmol L⁻¹ with correlation coefficients above 0.9938, and the recoveries were between 79.8% and 105.6% with the relative standard deviation values lower than 16.3% (n = 5). The limits of quantification of six aldehydes ranged from 13.8 to 64.6 nmol L⁻¹. The established method was successfully applied for the quantification of aldehyde metabolites in exhaled breath condensates of lung cancer patients and healthy people. Taken together, the TFME-HPLC method provides a simple, rapid, sensitive, cost-effective, non-invasion approach for the analysis of linear aliphatic aldehydes in human exhaled breath condensates.     

Comprehensive Two-Dimensional Gas Chromatography–Mass Spectrometry Analysis of Exhaled Breath Compounds after Whole Grain Diets

Exhaled breath is a potential noninvasive matrix to give new information about metabolic effects of diets. In this pilot study, non-targeted analysis of exhaled breath volatile organic compounds (VOCs) was made by comprehensive two-dimensional gas chromatography–mass spectrometry (GCxGC-MS) to explore compounds relating to whole grain (WG) diets. Nine healthy subjects participated in the dietary intervention with parallel crossover design, consisting of two high-fiber diets containing whole grain rye bread (WGR) or whole grain wheat bread (WGW) and 1-week control diets with refined wheat bread (WW) before both diet periods. Large interindividual differences were detected in the VOC composition. About 260 VOCs were detected from exhaled breath samples, in which 40 of the compounds were present in more than half of the samples. Various derivatives of benzoic acid and phenolic compounds, as well as some furanones existed in exhaled breath samples only after the WG diets, making them interesting compounds to study further.     

Detection of volatile organic compounds (VOCs) in exhaled breath of patients with chronic obstructive pulmonary disease (COPD) by ion mobility spectrometry

COPD is a disease characterised by a chronic inflammation of the airways and a not fully reversible airway obstruction. The spirometry is considered as gold-standard to diagnose the disease and to grade its severity. In this study we used the methodology of Ion Mobility Spectometry in order to detect Volatile Organic Compounds (VOCs) in exhaled breath of patients with COPD. The purpose of this study was to investigate if the VOCs detected in patients with COPD were different from the VOCs detected in exhaled breath of healthy controls. 13 COPD patients and 33 healthy controls were included in the study. Breath samples were collected via a side-steam Teflon tube and directly measured by an ion mobility spectrometer coupled to a multi capillary column (MCC/IMS). One peak was identified only in the patients group compared to the healthy control group. Consequently, the analysis of exhaled breath could be a useful tool to diagnose COPD.     

Correlation analysis on data sets to detect infectious agents in the airways by ion mobility spectrometry of exhaled breath

A correlation analysis of peaks found in IMS-Chromatograms was carried out to show the potential of the method in clinical applications. As an example, the data of exhaled breath of patients suffering infections of Pseudomonas were compared to healthy non-smokers. Using a rank sum calculation and providing a correlation table of all peaks found, delivers the basis for visualisation of highest ranked analytes. In addition, a consideration of positive and negative correlated peaks could support sub-grouping, if present. A set of signals could be found for discriminating the two groups of patients using MCC-IMS. Investigations of exhaled breath using ion mobility spectrometry seems to provide a promising means for the non-invasive identification of patients which are colonized or infected with bacteria such as Pseudomonas aeruginosa.     

One-year time series of investigations of analytes within human breath using ion mobility spectrometry

Ion mobility Spectrometry is used to detect volatile analytes within human breath directly. Many volatile organic compounds (VOC) show significant day-to-day variation in the signal height related to the concentration of the analyte, although the breath collection had been performed under the same conditions with respect to similar sampling procedure, similar dead volume, similar measurement time, and measurement conditions. Variations of 8 different analytes are investigated over a time period of 11 months in the exhaled breath of the same person in the same room environment. The individual variability is reported for Benzothiazole; D-Limonene; Eucalyptol; Decamethylcyclopentasiloxane; Decanal; 1-Hexanol, 2-ethyl-; Cyclohexanone, 5-methyl-2-(1-methylethyl) and Nonanal. The paper shows, that the individual variability must be taken into consideration to relate the findings to medical questions. Therefore, the room air concentration of VOCs must be taken into account, so that the difference between exhaled and inhaled air has to be used as indicator. Finally, starting with individual variabilities, the normal variation related to the specific analyte should be considered in addition.     

Non-labeling multiplex surface enhanced Raman scattering (SERS) detection of volatile organic compounds (VOCs)

In this paper, we report multiplex SERS based VOCs detection with a leaning nano-pillar substrate. The VOCs analyte molecules adsorbed at the tips of the nano-pillars produced SERS signal due to the field enhancement occurring at the localized surface plasmon hot spots between adjacent leaning nano-pillars. In this experiment, detections of acetone and ethanol vapor at different concentrations were demonstrated. The detection limits were found to be 0.0017 ng and 0.0037 ng for ethanol and acetone vapor molecules respectively. Our approach is a non-labeling method such that it does not require the incorporation of any chemical sensing layer for the enrichment of gas molecules on sensor surface. The leaning nano-pillar substrate also showed highly reproducible SERS signal in cyclic VOCs detection, which can reduce the detection cost in practical applications. Further, multiplex SERS detection on different combination of acetone and ethanol vapor was also successfully demonstrated. The vibrational fingerprints of molecular structures provide specific Raman peaks for different VOCs contents. To the best of our knowledge, this is the first multiplex VOCs detection using SERS. We believe that this work may lead to a portable device for multiplex, specific and highly sensitive detection of complex VOCs samples that can find potential applications in exhaled breath analysis, hazardous gas analysis, homeland security and environmental monitoring.     

Detection of infectious agents in the airways by ion mobility spectrometry of exhaled breath

Diseases of the lung, e. g. chronic obstructive pulmonary disease (COPD), interstitial lung diseases, bronchiectasis or cystic fibrosis, often lead to recurrent severe respiratory infections that cause exacerbations of the underlying disease. These acute or chronic inflammatory processes can result in a progressive destruction of the lung and in an ongoing decline in lung function. Therefore longer inpatient stays for intravenous antibiotic treatment are necessary and the quality of life in these patients is severely limited. A rapid detection of infectious agents in human lungs is often crucial, because the choice of the appropriate therapeutic regime depends at first on the identification of the infecting species. Standard methods for detection and identification are either time consuming, of low sensitivity or expensive. It is known that bacteria, and also mitosporic fungi, produce volatile organic compounds (VOCs) that can be detected in exhaled breath by ion mobility spectrometry (IMS), were a distinct detection of a specific VOC is related to a “peak”. We investigated, whether the detection and characterisation of VOCs by Multi-capillary column coupled to IMS in exhaled breath of patients whose airways are either infected or colonized by Pseudomonas aeruginosa compared to healthy non-smoker controls is capable of identifying those infectious agents. To realize a non invasive identification of pathogens, the exhaled breath of 53 persons (24 patients suffering chronic or infectious on Pseudomonas and 29 healthy controls) was investigated using an ion mobility spectrometer type BioScout. In total 224 different signals were found. Actually, 21 different signals are able to differentiate the two groups, Control and Pseudomonas, with rank sum values less than 0.2. For all 224 signals Box-and-Wisker plots were realized. The peaks with the lowest rank sum values F (0,107) and PS0 (0,112) show rather good separation of both groups. Our preliminary results demonstrate that distinct patterns of a small number of IMS-peaks are sufficient for the identification of these infectious agents. Therefore MCC-IMS seems to be a promising method for the non-invasive identification of patients which are colonized or infected with bacteria such as Pseudomonas aeruginosa.