Application of surface-enhanced Raman spectroscopy to human serum for diagnosing liver cancer.

This study investigates the application of surface-enhanced Raman spectroscopy (SERS) in the diagnosis of liver cancer using Ag@SiO2 nanoparticles as SERS substrates. A SERS test was conducted on serum samples obtained from patients with liver cancer and healthy individuals. After repeated several times experiments, it was found that the best SERS spectrum was obtained when the volume ratio of serum to deionized water was 1:2. Moreover, data preprocessing was performed on the tested SERS spectrum, and the preprocessed spectral data were combined with principal component analysis (PCA), partial least-squares discriminant analysis (PLS-DA), and orthogonal partial least squares discriminant analysis (OPLS-DA) for further analysis to classify the serum samples of patients with liver cancer and healthy individuals. The results showed that the classification effect of standard normal variate spectral data combined with the OPLS-DA was the best for the serum samples, with a classification accuracy of 97.98%, sensitivity of 97.14%, and specificity of 98.44%. Therefore, the SERS technology can be developed as a favorable method for the accurate diagnosis of liver cancer in the future.

Quantitative determination of carbosulfan residues by surface-enhanced Raman spectroscopy.

Carbosulfan gets easily decomposed into carbofuran and 3-Hydroxy carbofuran in vegetables and forms harmful residues. To detect the residues of carbosulfan in vegetables (for example, cowpeas), a super-sensitive method of surface-enhanced Raman spectroscopy (SERS) was used in this work. Silver sol was prepared as the SERS substrate. To solve the adsorption problem of carbosulfan on Ag nanoparticles, 2, 6-dichloroquinone-4-chlorimide (chromogenic agent), and sodium hydroxide were added in carbosulfan to generate a complex, which was then mixed with the silver sol in the best proportion to examine SERS spectra. According to density functional theory calculations, the spectral peak positions of carbosulfan were determined. The optimal mixing ratio of the complex and the silver sol to obtain the optimal SERS spectrum and the detection limit of carbosulfan were investigated. The ultra-sensitive detection of carbosulfan residues (8.7 × 10-11 g/L) in cowpeas was realized. The results of this work indicate that SERS is a promising technique for detecting single-molecule pesticide residues in vegetables.

High Sensing Performance Toward Acetone Vapor Using TiO2 Flower-Like Nanomaterials.

For real-application gas sensors, high performances (response, selectivity, response/recovery time and stability) are demanded. An effective strategy is applying nanomaterials in gas sensors. In this study, the anatase TiO2 flower-like nanomaterials (FLNMs) are prepared through a one-step hydrothermal method which exhibit high-performance toward acetone vapor. TiO2 FLNMs sensors property are characterized at optimal working temperature of 330 °C with selectivity (acetone), response (S = 33.72 toward 250 ppm acetone), linear dependence (R2 = 0.9913), response/recovery time (46/24 s toward 250 ppm acetone) and long-term stability (30 days). These demonstrate that TiO2 FLNMs get a high performance for acetone sensor. Moreover, the limit of detection of acetone is 0.65 ppm which is lower than that of exhaled air for diabetes (0.8 ppm), indicating that TiO2 FLNMs gas sensor gets potential application in medical diagnosis.

Ultrasensitive flower-like TiO2/Ag substrate for SERS detection of pigments and melamine.

TiO2 flower like nanomaterials (FLNMs) are fabricated via a hydrothermal method and Ag nanoparticles (NPs) are deposited via electron beam evaporation. Several biological pigments (CV, R6G and RhB) are selected as target molecules to investigate their surface enhanced Raman scattering (SERS) property. The results demonstrate ultrasensitivity and high reproducibility. They reveal that the limit of detection (LOD) is 4.17 × 10-16 M and the enhancement factor (EF) is 2.87 × 1010 for CV, and the LOD is 5.01 × 10-16 M and 7.94 × 10-14 M for R6G and RhB, respectively. To assess the reproducibility on TiO2/Ag FLNMs SERS substrates, they are tested with 1.0 × 10-13 M of CV, 1.0 × 10-13 M of R6G and 1.0 × 10-11 M of RhB, respectively. The relative standard deviations (RSD) are less than 12.93%, 13.52% and 11.74% for CV, R6G and RhB, respectively. In addition, we carry out melamine detection and the LOD is up to 7.41 × 10-10 M, which is over 1000 times lower than the severest standards in the world. Therefore, the obtained TiO2 FLNMs have potential application in detecting illegal food additives.

Diagnosis of Lung Cancer by FTIR Spectroscopy Combined With Raman Spectroscopy Based on Data Fusion and Wavelet Transform.

Lung cancer is a fatal tumor threatening human health. It is of great significance to explore a diagnostic method with wide application range, high specificity, and high sensitivity for the detection of lung cancer. In this study, data fusion and wavelet transform were used in combination with Fourier transform infrared (FTIR) spectroscopy and Raman spectroscopy to study the serum samples of patients with lung cancer and healthy people. The Raman spectra of serum samples can provide more biological information than the FTIR spectra of serum samples. After selecting the optimal wavelet parameters for wavelet threshold denoising (WTD) of spectral data, the partial least squares-discriminant analysis (PLS-DA) model showed 93.41% accuracy, 96.08% specificity, and 90% sensitivity for the fusion data processed by WTD in the prediction set. The results showed that the combination of FTIR spectroscopy and Raman spectroscopy based on data fusion and wavelet transform can effectively diagnose patients with lung cancer, and it is expected to be applied to clinical screening and diagnosis in the future.

Recyclable Ag-Deposited TiO2 SERS Substrate for Ultrasensitive Malachite Green Detection.

An ultrasensitive Ag-deposited TiO2 flower-like nanomaterial (FLNM) surface-enhanced Raman scattering (SERS)-active substrate is synthesized via a hydrothermal method, and Ag nanoparticles (NPs) are deposited through electron beam evaporation. Malachite green (MG), which is widely used in aquaculture, is employed to assess the surface-enhanced Raman scattering (SERS) properties of TiO2/Ag FLNMs. They exhibit ultrasensitivity (limit of detection (LOD) of MG reaches 4.47 × 10-16 M) and high reproducibility (relative standard deviations (RSDs) are less than 13%); more importantly, the TiO2/Ag FLNMs are recyclable, as enabled by their self-cleaning function due to TiO2 photocatalytic degradation. Their recyclability is achieved after three cycles and their potential application is examined in the actual system. Finite difference time domain (FDTD) simulations and the charge-transfer (CT) mechanism further prove that the excellent SERS properties originate from localized surface plasmon resonance (LSPR) of Ag NPs and the coupling field between Ag and TiO2 FLNMs. Therefore, TiO2/Ag FLNMs show promising application in aquaculture.

Diagnosis of Lung Cancer by ATR-FTIR Spectroscopy and Chemometrics.

Lung cancer is the leading cause of cancer-related death in the world. Early diagnosis has great significance for the survival of patients with lung cancer. In this paper, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy combined with chemometrics was used to study the serum samples from patients with lung cancer and healthy people. The results of spectral band area comparison showed that the concentrations of protein, lipid and nucleic acids molecules in serum of patients with lung cancer were increased compared with those in healthy people. The original spectra were preprocessed to improve the accuracy of principal component regression (PCR) and partial least squares-discriminant analysis (PLS-DA) models. PLS-DA results for first derivative spectral data in nucleic acids (1250-1000cm-1) band showed 80% sensitivity, 91.89% specificity and 87.10% accuracy with high R c 2 of 0.8949 and R v 2 of 0.8153, low RMSEC of 0.3136 and RMSEV of 0.4180. It is shown that ATR-FTIR spectroscopy combined with chemometrics might be developed as a simple method for clinical screening and diagnosis of lung cancer.

Diagnosis of liver cancer by FTIR spectra of serum.

Liver cancer is the most common fatal malignant tumor in the world. Early diagnosis of liver cancer can improve the survival rate of the patients with liver disease. In this paper, Fourier transform infrared (FTIR) spectroscopy combined with curve fitting and chemometrics was used to distinguish the serum from patients from that of healthy people. The curve fitting results in protein range of 1700-1600 cm-1 showed that there were differences in the secondary structure of protein in serum between the patients with liver cancer and healthy people. Principal component analysis (PCA) in lipid range of 2900-2800 cm-1 could distinguish the serum of patients with liver cancer from that of healthy people. The first two principal components PC1 and PC2 explained 95% of the total data variance. The sensitivity and specificity of partial least squares discriminant analysis (PLS-DA) in lipid range of 2900-2800 cm-1 reached 92.85% and 95.23% respectively. It is shown that FTIR spectroscopy might be developed as an effective method for the diagnosis of liver cancer.

Soil-applied selenite increases selenium and reduces cadmium in roots of Moringa oleifera.

Deficiency of selenium (Se) will lead to malnutrition and decreased immune function of the body. There is a common phenomenon of Se deficiency in foods. In this study, different concentrations of sodium selenite (Na2SeO3) were applied to Moringa oleifera grownin soil. The purpose was to explore the feasibility of Se biofortification of M. oleifera root. The effect of exogenous Se on the accumulation of Se and cadmium (Cd) in the roots of M. oleifera was studied by inductively coupled plasma mass spectrometry, and the mechanism of exogenous Se on the accumulation of Se and Cd in the roots was studied by Fourier transform infrared spectroscopy (FTIR) combined with principal component analysis and partial least squares regression analysis. The results showed that Na2SeO3 significantly affected the accumulation of Se and Cd in the roots (p < 0.05). The increase in Se was highest when Na2SeO3 was around 4.0 mg/kg, which increased by 315% compared with the control. The decrease in Cd was the lowest when Na2SeO3 was around 2.0 mg/kg, which decreased by 80% compared with the control. The results of FTIR analysis showed that Na2SeO3 treatment changed the carboxylate, phosphate radical, hemicellulose and protein in roots of M. oleifera, while the increase of Se was related to hemicellulose, protein, polysaccharide and lignin, and the decrease of Cd was related to hemicellulose and protein. The results showed that exogenous Se increased the accumulation of Se and inhibited the absorption of Cd. Therefore, the roots of M. oleifera can be used in Se biofortified products.

Design of spherical aberration free liquid-filled cylindrical zoom lenses over a wide focal length range based on ZEMAX.

A systematic design idea for liquid-filled cylindrical zoom lenses with ideal imaging quality over a wide focal length range is introduced in detail. The PWC method is used to calculate the initial structure parameters of the zoom lenses, and the optical design software ZEMAX is used to eliminate the spherical aberration at different focal lengths. Lenses named SLCL-Doublet are finally designed, which are formed by a symmetric liquid-core cylindrical lens (SLCL) filled with variable refractive index (RI) liquid and a doublet cylindrical lens capable of significantly weakening the spherical aberration. The focal length of the SLCL-Doublet continuously decreases from 101.406 mm to 54.162 mm as the liquid RI changes from 1.3300 to 1.5000. Calculated over 75% of the full aperture, the root mean square (RMS) spot radius of the SLCL-Doublet is always less than 7 µm over the whole focal length range, and the peak-to-valley wavefront error remains below the λ/4 limit when the focal length ranges from 62.373 mm to 65.814 mm, within which the lenses approach the diffraction limit, demonstrating improvement in the optical performance over that of previously designed liquid-core cylindrical lenses. The sources of potential fabrication and installation errors in the practical implementation of the SLCL-Doublet are also analyzed in detail. The SLCL-Doublet is demonstrated to be characterized by high imaging quality and easy installation, which enriches the types of core optical element for measuring the liquid RI and liquid diffusion coefficient and provides guarantee for improving the measurement accuracy.

Seed-Mediated Electroless Deposition of Gold Nanoparticles for Highly Uniform and Efficient SERS Enhancement.

A seed-mediated electroless deposition (SMED) approach for fabrication of large-area and uniform gold nanoparticle films as efficient and reproducible as surface-enhanced Raman scattering (SERS) substrates was presented. This approach involved a seeding pretreatment procedure and a subsequent growth step. The former referred to activation of polylysine-coated glass slides in gold seed solution, and the latter required a careful control of the reactant concentration and reaction time. With the aid of gold seeds and appropriate reaction conditions, a large-area and uniform nanofilm with evenly distributed gold nanoparticles (Au NPs) was formed on the surface of the substrates after adding a mixed solution containing ascorbic acid and trisodium citrate. The morphology of the Au nanofilm was examined by scanning electron microscopy. The size evolution of Au NPs on the surface of the substrates was analyzed in detail. The nanofilm substrate was prepared by reaction conditions of the seeded activation process: 10 mL ascorbic acid and trisodium citrate mixture and 30 min of soaking time, which exhibited an excellent uniformity and reproducibility of SERS enhancement with relative standard deviation (RSD) values of less than 8% (particularly, a RSD value of 3% can be reached for the optimized measurement). Compared to the common electroless deposition, the seed-mediated electroless deposition possessed inherent advantages in controllability, reproducibility, and economic benefit.

Hydroxide assisted synthesis of monodisperse and biocompatible gold nanoparticles with dextran.

A simple and rapid approach to synthesize monodisperse and biocompatible gold nanoparticles (AuNPs) employing dextran as a reducing and stabilizing agents at different reaction conditions was described. The obtained dextran-gold nanoparticles (Dex-AuNPs) were characterized by transmission electron microscopy (TEM), UV-Vis spectroscopy, Nuclear magnetic resonance (NMR) spectroscopy, Fourier transformer infrared (FTIR) spectroscopy and X-ray diffraction (XRD) analysis. The TEM examinations showed the resultant particles were 4-50 nm in size, monodispersity and uniform particle size distribution. Moreover, the size of the nanoparticles can be controlled by varying the concentration of the reactants. UV-Vis spectra showed that the characteristic localized surface plasmon resonance (LSPR) band of AuNPs was at about 525 nm. NMR spectroscopy and FTIR spectroscopic analysis suggested the detailed structural information of dextran before and after synthesis of AuNPs. XRD and selected area electron diffraction (SAED) pattern analysis demonstrated that the colloidal nanoparticles had a well crystallized structure. The experimental analyses revealed that NaOH played an important role in the synthesis of Dex-AuNPs. And the possible formation mechanism of the fabrication of these Dex-AuNPs was also proposed. MTT assay was utilized to evaluate the cytotoxicity of the synthesized Dex-AuNPs on HeLa cells and SiHa cells. These results suggested that the prepared Dex-AuNPs complexes had excellent biocompatibility and acted as a candidate for further biomedical application.

Calculation extinction cross sections and molar attenuation coefficient of small gold nanoparticles and experimental observation of their UV-vis spectral properties.

Gold nanoparticles (AuNPs) have been researched extensively, such as applied in various biosensors, biomedical imaging and diagnosis, catalysis and physico-chemical analysis. These applications usually required to know the nanoparticle size or concentration. Researchers have been studying a simply and quick way to estimate the concentration or size of nanoparticles from their optical spectra and SPR feature for several years. The extinction cross-sections and the molar attenuation coefficient were one of the key parameters. In this study, we calculated the extinction cross-sections and molar attenuation coefficient (decadic molar extinction coefficient) of small gold nanoparticles by dipole approximation method and modified Beer-Lambert law. The theoretical result showed that the surface plasmon resonance peak of small gold nanoparticles was blueshift with an increase size. Moreover, small AuNPs (sub-10nm) were prepared by using of dextran or trisodium citrate as reducing agent and capping agent. The experimental synthesized AuNPs was also shows a blueshift as increasing particle size in a certain range. And the concentration of AuNPs was calculated based on the obtained molar attenuation coefficient. For small nanoparticles, the size of nanoparticles and surface plasmon resonance property was not showed a positive correlation compared to larger nanoparticles. These results suggested that SPR peak depended not only on the nanoparticle size and shape but also on the nanoparticles environment.

[Discrimination of Lactarius and Russula Mushrooms with FTIR and Two-Dimensional Correlation Infrared Spectroscopy].

Tri-step infrared spectroscopy method of Fourier transform infrared spectroscopy, second derivative infrared spectroscopy and two-dimensional correlation infrared spectroscopy was firstly used to discriminate six species of mushrooms belonging to the genus Lactarius and Russula. The absorption bands of the original spectrum were very similar, which were composed by protein and polysaccharides, but tiny differences were observed at the position, shape and absorption intensities of peaks. Second derivative infrared spectroscopy technology was applied to study 6 species of the samples, there were obvious differences in the range of 1 800～1 400 and 1 200～800 cm-1. Two-dimensional correlation infrared spectroscopy can improve the resolution of spectra. Therefore two-dimensional correlation infrared spectroscopy was used to study 6 kinds of mushrooms. The results showed that there are three auto-peaks in the Lactarius, four in the Russula and significant differences in the number, intensity of auto-peaks and cross peaks were observed in the range of 1 690~1 420 cm-1. In addition, the peaks quantity, position, intensity of auto-peaks and cross peaks were different in the range of 1 110~920 cm-1. It demonstrates that tri-step infrared spectroscopy technology of Fourier transform infrared spectroscopy, second derivative infrared spectroscopy and two-dimensional correlation infrared spectroscopy is a rapid and effective method for discriminating Lactarius and Russula.

[Discrimination of Seven Species of Boletus with Fourier Transform Infrared Spectroscopy].

Fourier transform infrared spectroscopy, two-dimensional correlation infrared spectroscopy and principal component analysis were used to discriminate seven species of boletus belonging to the same genus. The results showed that the absorption bands of original spectra were similar, which were mainly composed of the absorption bands of protein and polysaccharides, but tiny differences were still observed at the position and intensities of peaks. Two-dimensional correlation infrared spectroscopy technology was applied to study the sample. It showed that there are 6 auto-peaks in the Boletus brunneissimus Chiu and Boletus bicolor, 5 auto-peaks in the Boletus speciosus, 4 auto-peaks in the Boletus griseus Forst and Boletus calopus, only 3 in the Boletus edulis and Boletus aereus in the range of 1 680~1 300 cm-1. The significant differences in the position, intensity of auto-peaks and cross peaks were still observed in the range of 1 680~1 300 cm-1. Same significant differences were observed in the range of 1 150~920 cm-1. Principal component analysis was conducted on boletus with second derivative infrared spectra in the range of 1 800~800 cm-1. All the samples were distinguished and the classification accuracy of principal component analysis is up to 100%. It is demonstrated that Fourier transform infrared spectroscopy combined with two-dimensional correlation infrared spectroscopy or principal component analysis is a rapid and effective method for discriminating mushrooms.

[Analysis of different types of soil by FTIR and ICP-MS].

Fourier transform infrared spectroscopy (FTIR) and inductively coupled plasma mass spectrometry (ICP-MS) were used to study six types of farmland soil from different areas. The FTIR results showed that the infrared spectra of soil were mainly composed of the absorption band of clay minerals, organic matter and inorganic salts, such as carbonate, phosphate, manganate and so on. The mineral atlas of six soil samples were all of montmorillonite type. The ICP-MS test results showed that the available elements content of different types and colours of soil samples were different There was significant lack status of available Ca between different types of farmland soil, the content of available Mg in Huludao soil was in the medium level, other areas were in the status of shortage. There was only significant lack status of available Mn and available Zn in Baiyin soil, the content of available Fe in Chenggong soil was in the status of shortage, the content of available Cu in all areas was particularly rich. The content of available P in Jining soil was rich, Luoyang and Huludao soil were in the medium level, the soil of Chenggong, Baiyin and Luliang were in the status of shortage. The content of available K in Luoyang, Chenggong and Jining soil was relatively rich, Luliang soil was in the medium level, the soil of Huludao and Baiyin were in the status of shortage. It is observed that the deeper the color of soil samples, the richer the amount of some available trace elements such as magnesium, copper, iron, manganese and zinc. According to the national classification standard of available elements content, we analyzed the nutrients of available elements content in the farmland soil of different areas, and implemented remedial measures for the lacking of available elements for all of the six areas.

[FTIR study of the influence of leaf senescence on magnoliaceae cluster analysis].

Fourier transform infrared (FTIR) spectroscopy combined with hierarchical cluster analysis was used to study the influence of leaf senescence on magnoliaceae cluster. FTIR spectra of young, mature and old yellow leaves were obtained from 14 species trees belonging to the three magnoliaceae subtribes. Results showed that the infrared spectra of the three subtribes plant leaves were similar, only with minor differences in the absorption intensity of several peaks. Hierarchical cluster analysis was performed on the second derivative infrared spectra in the range 1800-700 cm(-1). The HCA results showed that the cluster based on mature leaves is better than that based on young and old yellow leaves. Our study suggests that it should be cautious to select leaf sample while using leaf spectra for classification.

[Infrared spectroscopic study on leaf senescence of evergreen tree].

In order to investigate plant physiological process of leaf senescence and aging, Fourier transform infrared (FTIR) spectroscopy was used to study the young, mature, and old yellow leaves from seven species of evergreen trees. The spectra of the leaves from different growing period are different in the region of 1 800-700 cm(-1). The absorption ratios A1 070/A2 927, A1 070/A1 160 were used to evaluate the relative changes of polysaccharides, and A1 318/A2 922 was used to estimate the change of calcium oxalate during leaf senescence. Decomposition and curve-fitting analysis was performed in the region of 1 800 -1 500 cm(-1). The sub-band absorption ratio H1 650/H1 740 was used to evaluate the relative changes of protein in the leaves. The results show that the accumulation and mobilization of polysaccharides, protein, and calcium oxalate during leaf growing period were different in different plant species. This study demonstrates the potential of mid-infrared spectroscopy for investigation of plants senescence, as well as physiological and biochemical changes of plants.

[Discrimination of bamboo using FTIR spectroscopy and statistical analysis].

Fourier transform infrared (FTIR) spectroscopy combined with principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used to identify and classify bamboo leaves. FTIR spectra of fifty-four bamboo leaf samples belonging to six species were obtained. The results showed that the infrared spectra of bamboo leaves were similar, and mainly composed of the bands of polysaccharides, protein and lipids. The original spectra exhibit minor differences in the region of 1800-700cm-1. The second derivative spectra show apparent differences in the same region. Principal component analysis and hierarchical cluster analysis were performed on the second derivative infrared spectra in the range from 1800 to 700 cm-1. The leaf samples were separated into 6 groups with accuracy of 98% with the first three principal components, and with 100% accuracy according to the third and fourth principal components. Hierarchical cluster analysis can correctly cluster the bamboo leaf samples. It is proved that Fourier transform infrared spectroscopy combined with PCA and HCA could be used to discriminate bamboo at species level with only a tiny leaf sample.

[Research on rice blast, corn and broad bean rust leaves by FTIR spectroscopy].

Fourier transform infrared Spectroscopy (FTIR) was used to study healthy and diseased leaves of rice, corn, and broad bean. The results show that the infrared spectra of the leaves are mainly composed of the absorption bands of proteins and polysaccharide. The spectra are similar, but the differences were observed in the peak positions, shapes, and absorption ratios. The remarkable differences in correlation coefficients were also observed in the region of 1 800-1 000 cm(-1) of the second derivate spectra. The absorption ratio A1 056 /A1 652 of healthy rice leaves and rice blast leaves, A1 652/A2 920 of healthy broad bean leaves and leaves, A1 056/A2 920 of healthy corn and corn rust (non-lesion site), and A1 652/A2 920 of healthy corn and corn rust (lesion site) all show a decline from healthy to diseased leaves, showing that the contents of polysaccharide and the protein have some differences.