Detection and analysis of microplastics in tissues and blood of human cervical cancer patients.

Microplastics (MPs) can enter the reproductive system and can be potentially harmful to human reproductive health. In this study, 13 types of microplastics (MPs) were identified in patient blood, cancer samples, and paracarcinoma samples using Raman spectroscopy, with polyethylene, polypropylene and polyethylene-co-polypropylene being the most abundant polymer types. Futher, cotton was also found in our study. The diversity and abundance of MPs were higher in blood samples than in cancerous tissues, and there was a significant positive correlation between diversity (p < 0.05). Furthermore, the diversity and abundance of MPs in cancerous tissues were higher than in paracancerous tissues. The dimensional sizes of MPs in these samples were also very similar, with the majority of detected MPs being smaller in size. Correlation analysis showed that patient's age correlated with the abundance of MPs in blood samples, body mass index (BMI) correlated with the abundance of MPs in cancerous tissues. Notably, the frequency with which patients consume bottled water and beverages may also increase the abundance of MPs. This study identifies for the first time the presence of MPs and cotton in cancerous and paracancerous tissues of human cervical cancer patients. This provides new ideas and basic data to study the risk relationship between MP exposure and human health.

High-speed monitoring of the crystallinity change in poly(lactic acid) during photodegradation by using a newly developed wide area NIR imaging system (Compovision).

We aimed to achieve wide area rapid monitoring of the crystallinity change in poly(lactic acid) (PLA) during photodegradation caused by ultraviolet (UV) light by using a newly developed near-infrared (NIR) camera (Compovison). Several kinds of PLA samples with different crystallinities and their blends with poly[(3)-(R)-hydroxybutyrate] were prepared. Their two-dimensional NIR spectra in the 1,000-2,350-nm region were measured by Compovision at a 5-min interval during photolysis. An intensity decrease of the band in the 1,900-1,925-nm region due to the second overtone of the C = O stretching vibration of PLA was observed during photolysis. This suggests that an anhydride carbonyl is produced during photolysis. The NIR image of the crystallinity change monitored by the band at 1,917 nm in the standard normal variate spectra clearly shows the inhomogeneity of crystal evolution. A logarithmic increase was observed for all identified areas in the PLA film; however, the time to reach the maximum crystallinity was slightly different according to the initial crystallinity of the sample. It is likely that the initial crystallinity of the sample influences the degradation speed more than the degradation amount. These imaging results have provided fundamental chemical insights into the photolytic process for PLA, and at the same time they have demonstrated that the two-dimensional spectral data obtained by Compovision are useful for process monitoring of polymers.

The effect of microcrystalline cellulose crystallinity on the hydrophilic property of tablets and the hydrolysis of acetylsalicylic acid as active pharmaceutical ingredient inside tablets.

The crystal structures of active pharmaceutical ingredients and excipients should be strictly controlled because they influence pharmaceutical properties of products which cause the change in the quality or the bioavailability of the products. In this study, we investigated the effects of microcrystalline cellulose (MCC) crystallinity on the hydrophilic properties of tablets and the hydrolysis of active pharmaceutical ingredient, acetylsalicylic acid (ASA), inside tablets by using tablets containing 20% MCC as an excipient. Different levels of grinding were applied to MCC prior to tablet formulation, to intentionally cause structural variation in the MCC. The water penetration and moisture absorbability of the tablets increased with decreasing the crystallinity of MCC through higher level of grinding. More importantly, the hydrolysis of ASA inside tablets was also accelerated. These results indicate that the crystallinity of MCC has crucial effects on the pharmaceutical properties of tablets even when the tablets contain a relatively small amount of MCC. Therefore, controlling the crystal structure of excipients is important for controlling product qualities.

Near-Infrared Imaging Using a High-Speed Monitoring Near Infrared Hyperspectral Camera (Compovision).

This review paper reports near-infrared (NIR) imaging studies using a newly-developed NIR camera, Compovision. Compovision can measure a significantly wide area of 150 mmX 250 mm at high speed of between 2 and 5 s. It enables a wide spectral region measurement in the 1,000-2,350 nm range at 6 nm intervals. We investigated the potential of Compovision in the applications to industrial problems such as the evaluation of pharmaceutical tablets and polymers. Our studies have demonstrated that NIR imaging based on Compovision can solve several issues such as long acquisition times and relatively low sensitivity of detection. NIR imaging with Compovision is strongly expected to be applied not only to pharmaceutical tablet monitoring and polymer characterization but also to various applications such as those to food products, biomedical substances and organic and inorganic materials.

Assessment of active pharmaceutical ingredient particle size in tablets by Raman chemical imaging validated using polystyrene microsphere size standards.

Particle size is a critical parameter for controlling pharmaceutical quality. The aim of this study was to assess the size of the micrometer-scale active pharmaceutical ingredients (API) in tablets using Raman chemical imaging and to understand the effects of formulation on particle size. Model tablets containing National Institute of Standards and Technology traceable polystyrene microsphere size standards were developed to determine the binarization threshold value of Raman chemical images for API particle sizing in specific formulations and processes. Three sets of model tablets containing 5, 10, and 15 µm polystyrene microspheres, used to mimic API, were prepared using a commercial tablet formulation (Ebastel tablets, mean API particle size was about 5 µm). Raman mapping with a 50× objective (NA, 0.75) was applied to tablet cross-sections, and particle size of polystyrene microspheres was estimated from binary images using several binarization thresholds. Mean particle size for three sets of polystyrene microspheres showed good agreement between pre- and postformulation (the slope = 1.024, R = 1.000) at the specific threshold value ((mean + 0.5σ) of the polystyrene-specific peak intensity histogram), regardless of particle agglomeration, tablet surface roughness, and laser penetration depth. The binarization threshold value showed good applicability to Ebastel tablets, where the API-specific peak intensity histogram showed a pattern similar to that of polystyrene microspheres in model tablets. The model tablets enabled determination of an appropriate binarization threshold for assessing the mean particle size of micrometer-scale API in tablets by utilizing the unique physicochemical properties of polystyrene microspheres.

First identification of microplastics in human uterine fibroids and myometrium.

Microplastics (MPs) pollution has received widespread attention in recent years as the use of plastics continues to increase. However, currently no studies have reported the finding of MPs in human uterine fibroids (UFs) and myometrium tissues. In this study, UFs tissues (n = 48) and myometrium tissues (n = 40) from 48 patients and myometrium tissues (n = 8) from healthy population were collected. Following digestion of the samples by 10% KOH and 30% H2O2, MPs were analyzed qualitatively and quantitatively using Raman spectroscopy. The 16 UFs and myometrium tissue samples contained an average of 1.5 ± 1.17 MP particles per gram of tissue. Notably, the abundance of MPs in the UFs tissues (2.13 ± 1.17 particles per gram) was higher than in the myometrium tissues (0.88 ± 0.78 particles per gram). In the same cohort of individuals with UFs, the quantities of MPs detected in the affected UFs tissue (2.63 ± 1.77 particles per gram) exceeded those detected in healthy tissue (1.08 ± 0.93 particles per gram), particularly in elderly patients. A correlation was observed between elevated MP levels and frequent consumption of takeout meals and bottled water among patients, indicating that MP ingestion through food sources might have contributed to the increased abundance and variety of MPs within UFs. Furthermore, UFs increased in size with higher concentrations of MPs, which may have been related to elevated levels of MPs-induced hormones. This study provides new insights into the assessment of the relationship between exposure to MPs and human disease risk.

A study on the interaction of single-walled carbon nanotubes (SWCNTs) and polystyrene (PS) at the interface in SWCNT-PS nanocomposites using tip-enhanced Raman spectroscopy.

Normal Raman and tip-enhanced Raman scattering (TERS) spectra were recorded for single-walled carbon nanotube (SWCNT)-polystyrene (PS) nanocomposites to investigate the distribution of SWCNTs in the nanocomposites and local interactions at an interface between SWCNTs and PS. The normal Raman spectra do not show an evident point-to-point variation. In contrast, in the TERS spectra, Raman bands of SWCNTs show obvious point-to-point shifts; the shifts depend on the points. The shift of the G' band which has high sensitivity to the mechanical compression reflects its distribution at the surface of composites. The shift of the G band arises from two reasons: the disentanglement of SWCNTs in the SWCNT-PS system due to the penetration of PS chains into SWCNT bundles during melt mixing and the mechanical compression distribution from the PS matrix. Moreover, the relative intensity of the G' band and the Raman band of PS at 3058 cm(-1) changes with the points in the TERS spectra of the nanocomposites, which further reflects the dispersion state of SWCNTs in the polymer matrix. This study demonstrates that TERS has great potential to be applied to polymer nanocomposite materials for local structure and function studies.

Direct conversion of silver complexes to nanoscale hexagonal columns on a copper alloy for plasmonic applications.

We introduced a novel method for the rapid synthesis of silver nanohexagonal thin columns from an aqueous mixture of sodium thiosulfate (Na2S2O3) and silver chloride (AgCl) simply added to a phosphor bronze substrate. The reaction is based on galvanic displacement and the products are potentially useful for plasmonic applications.

Biogenic apatite in carbonate concretions with and without fossils investigated in situ by micro-Raman spectroscopy.

Micro-Raman spectra of concretions with and without fossils were measured in a nondestructive manner. The band position and full width at half maximum height (FWHM) of ν1-PO43- of apatite in the concretions were analyzed to investigate the origin of apatite. The analyzed concretions were derived from the Kita-ama Formation of the Izumi Group, Japan. The micro-Raman analysis showed that the apatites in the concretions were divided into two groups: Group W (wide FWHM group) and Group N (narrow FWHM group). The apatite belonging to Group W is suggested to be biogenic apatite originating from the soft body tissues of organisms because the Sr content is high and the FWHM is similar to that of apatite in bones and teeth of present-day animals. The other apatite belonging to Group N is considered affected by the diagenetic process because of its narrow FWHM and F substitution. These features of both groups were observed regardless of the presence of fossils or absence of fossils in the concretions. This Raman spectroscopic study suggests that the apatite at the time of concretion formation belonged to Group W but was changed to Group N by the substitution of F during the diagenesis process.

Detection of prostate cancer biomarkers via a SERS-based aptasensor.

The overexpression of specific biomarkers in serum is closely related to diseases, and accurate and sensitive detection of them is beneficial for the early diagnosis and treatment of cancer. In this study, we developed a novel surface-enhanced Raman spectroscopy (SERS)-based aptasensor to detect the prostate-specific antigen biomarkers, consisting of total prostate-specific antigen (PSA) and free prostate-specific antigen (f-PSA). A composite structure containing arrays of polystyrene colloidal sphere @Ag shell (PS@Ag) was fabricated as a SERS-active chip. A complementary DNA probe (SH-DNA) and PSA aptamer (Apt) were immobilised stepwise on the chip, followed by the binding of a Raman reporter methylene blue (MB) to the guanine base of the aptamer. PSA-Apt recognition causes the release of MB-Apt and a decrease in the SERS intensity of MB on the chip, which correlates with the PSA concentration. The proposed biosensor has high spectral reproducibility, selectivity, and sensitivity and successfully determines the PSA levels in serum samples collected from prostate cancer patients, demonstrating great potential for clinical diagnosis.

Multiple perturbation two-dimensional correlation analysis of cellulose by attenuated total reflection infrared spectroscopy.

An extension of the two-dimensional (2D) correlation analysis scheme for multi-dimensional perturbation is described. A simple computational form is provided to construct synchronous correlation and disrelation maps for the analysis of microscopic imaging data based on two independent perturbation variables. Sets of time-dependent attenuated total reflection infrared (ATR-IR) spectra of water and cellulose mixtures were collected during the evaporation of water from finely ground cellulose. The system exhibits complex behaviors in response to two independent perturbations, i.e., evaporation time and grinding time. Multiple perturbation 2D analysis reveals a specific difference in the rate of evaporation of water molecules when accompanied by crystallinity changes of cellulose. It identifies subtle differences in the volatility of water, which is related to the crystalline structure of cellulose.

Reusable Silicon-Based SERS Chip for Ratiometric Analysis of Fluoride Ion in Aqueous Solutions.

An innovative ratiometric surface-enhanced Raman scattering (SERS) sensor using a 4-mercaptoboric acid (4-MPBA)-modified silver nanoparticle-decorated silicon wafer (Si@Ag NPs chip) was proposed for the ultrasensitive determination of F- ions in aqueous solutions. The principle of sensing strategy is based on fluoride-induced structural symmetry breaking and charge redistribution of phenylboronic acid, leading to a band shift of the C-C stretching mode of 4-MPBA from 1589 to 1576 cm-1. Accordingly, a ratiometric signal of the area ratio (A1576/A1589) between the fluoride-bond MPBA molecules and unoccupied MPBA molecules can be used for the quantitative response of F- ions. In comparison with other SERS-based sensing methods, this ratiometric method can avoid a large error resulting from the inhomogeneity of substrates. Under the optimized analytical conditions, the proposed SERS sensor possesses a quick response to F- ions within 2 min and exhibits high selectivity for F- ions with the determination limit of 10-8 M, which is over 3 orders of magnitude lower than the World Health Organization (WHO) guideline value for F- ions in drinking water. Of particular significance, the present sensor features favorable recyclability, which preserves suitable reproducibility during 6-time cyclic determination of F- ions. The practical utility of this sensing system for the determination of F- ions was tested with real water and toothpaste samples, and the results demonstrate that this sensor shows high recoveries (90-110%). Given its simple principle and easy operation, the present silicon-based SERS sensor could serve as a promising sensor for various practical applications.

Analytical technique for label-free multi-protein detection based on Western blot and surface-enhanced Raman scattering.

We have developed a new analytical procedure for label-free protein detection designated "Western SERS", consisting of protein electrophoresis, Western blot, colloidal silver staining, and surface-enhanced Raman scattering (SERS) detection. A novel method of silver staining for Western blot that uses a silver colloid, an excellent SERS-active substrate, is first proposed in the present study. During the process of silver staining, interactions between proteins and silver nanoparticles result in the emergence of SERS of proteins. In the present study, we use myoglobin (Mb) and bovine serum albumin (BSA) as model proteins. From different protein bands on a nitrocellulose (NC) membrane, we have observed surface-enhanced resonance Raman scattering (SERRS) spectra of Mb and SERS spectra of BSA. The proposed technique offers dual advantages of simplicity and high sensitivity. On one hand, after the colloidal silver staining, we can detect label-free multi-proteins directly on a NC membrane without digestion, extraction, and other pretreatments. On the other hand, the detection limit of the Western SERS is almost consistent with the detection limit of colloidal silver staining, and the SERRS detection limit of Mb is found to be 4 ng/band. This analytical method, which combines the technique of protein separation with SERS, may be a powerful protocol for label-free protein detection in proteomic research.

Melt crystallization and crystal transition of poly(butylene adipate) revealed by infrared spectroscopy.

The structure evolution of poly(butylene adipate) (PBA) during isothermal melt crystallization and phase transition processes is investigated by Fourier transform infrared spectroscopy (FTIR). Detailed IR spectra analysis and band assignment are performed to disclose the bands sensitive to the alpha-form crystalline order of PBA. It is revealed from the in situ IR study that the functionalities within PBA chains alter simultaneously during the melt crystallization process. From the analysis of the spectral changes, it is found that band shifts take place during the phase transition process of PBA from its metastable beta-form crystal to the stable alpha-form. Notable band shifts in the 1300-1100 cm(-1) region indicate that the twist of polymer chains in the alpha-form is located in the C-O-C and C-O linkages. Moreover, the results elucidated that the different segments of molecular chains tune up their conformations synchronously during the beta to alpha crystal transition process of PBA. It is suggested that the betaalpha phase transition process proceeds randomly throughout the solid at a constant rate.

Structural evolution in microbial polyesters.

The crystallization behavior of microbially synthesized poly(3-hydroxybutyrate) (PHB) and its copolymers [P(HB-co-HHx)] containing 2.5, 3.4, and 12 mol % 3-hydroxyhexanoate (HHx) comonomer and the melting of the resultant crystals were studied in detail using time-resolved small-angle X-ray scattering and differential scanning calorimetry. The polyesters were found to undergo primary crystallization as well as secondary crystallization. In the primary crystallization, the thicknesses of the lamellar crystals were sensitive to the crystallization temperature, but no thickening was observed throughout the entire crystallization at a given temperature. The thickness of the lamellar crystals in the PHB homopolymer was always larger than that of the amorphous layers. In the copolymers, by contrast, the randomly distributed HHx comonomer units were found to be excluded from the lamellar crystals into the amorphous regions during the isothermal crystallization process. This interrupted the crystallization of the copolymer chains, resulting in the formation of lamellar crystals with thicknesses smaller than those of the amorphous layers. The lamellar crystals in the copolymers had lower electron densities compared to those formed in the PHB homopolymer. On the other hand, secondary crystallization favorably occurred during the later stage of isothermal crystallization in competition with the continuous primary crystallization, forming secondary crystals in amorphous regions, in particular in the amorphous layers between the primarily formed lamellar crystal stacks. Compared to the primarily formed lamellar crystals, the secondary crystals had short-range-ordered structures of smaller size, a broader size distribution, and a lower electron density.

Multivariate curve resolution analysis on the multi-component water sorption process into a poly(2-methoxyethyl acrylate) film.

In our previous study, sorption process of water into a biocompatible polymer film, poly(2-methoxyethyl acrylate) (PMEA) was monitored by time-resolved in situ attenuated total reflection infrared (ATR-IR) spectroscopy [S. Morita, et al., Langmuir 23, 3750 (2007)]. In the present study, noisy and heavily overlapped O-H stretching vibrational bands of diffusing water have been analyzed from the series spectra where the spectral shapes change irregularly with time. In spite of these complications, a powerful spectral analysis technique, multivariate curve resolution (MCR) by means of alternating least squares (ALS), yielded smooth and meaningful pure component spectra and detailed kinetic sorption profiles of each component, excluding noise. Ordinary smoothing techniques and Gaussian curve fitting would not achieve these significant results. The quantification of the kinetic parameters such as amplitudes (a) and relaxation time constants (tau) is significant for the systematic development of biocompatible materials and also for revealing the mechanisms of biocompatibility of a material. Moreover, the ratios of coefficients of each component at saturation corresponded well to the values obtained by Tanaka et al. measured by gravimetric analysis. This study is the first to report the detailed concentration profile of each water component whose sorption kinetics is discussed comprehensively.

Contribution of intramolecular C=O...H-N hydrogen bonding to the solvent-induced reentrant phase separation of poly(N-isopropylacrylamide).

Changes in the local environment around amide groups of poly(N-isopropylacrylamide) (PNiPA) during a solvent-induced reentrant phase separation have been investigated by infrared spectroscopy combined with quantum chemical calculations. The addition of methanol or tetrahydrofuran as a cosolvent to an aqueous solution of PNiPA causes spectral changes in the amide I regions. By preparing a dimer model compound for PNiPA, we can establish the assignment of the amide I bands for the polymer in solutions. Hydrogen-deuterium exchange experiments of the amide protons of PNiPA and its dimer models have revealed that the amide groups of PNiPA form an intramolecular C=O...H-N hydrogen bond even in a good solvent. The result has suggested that the change in the amide I envelope of PNiPA observed during the solvent-induced phase transition reflects the modification of the intramolecular C=O...H-N hydrogen bond of PNiPA as well as the variation in solvation state of the amide groups. On the basis of the assignment, we have discussed contributions of the intramolecular C=O...H-N hydrogen bond to the phase behavior of PNiPA.

Phase angle description of perturbation correlation analysis and its application to time-resolved infrared spectra.

A method of spectral analysis, phase angle description of perturbation correlation analysis, is proposed. This method is based on global phase angle description of generalized two-dimensional (2D) correlation spectroscopy, proposed by Shin-ichi Morita et al., and perturbation-correlation moving-window 2D (PCMW2D) correlation spectroscopy, proposed by Shigeaki Morita et al. For a spectral data set collected under an external perturbation, such as time-resolved infrared spectra, this method provides only one phase angle spectrum. A phase angle of the Fourier frequency domain correlation between a spectral intensity (e.g., absorbance) variation and a perturbation variation (e.g., scores of the first principle component) as a function of spectral variable (e.g., wavenumber) is plotted. Therefore, a degree of time lag of each band variation with respect to the perturbation variation is directly visualized in the phase angle spectrum. This method is applied to time-resolved infrared spectra in the O-H stretching region of the water sorption process into a poly(2-methoxyethyl acrylate) (PMEA) film. The time-resolved infrared (IR) spectra show three broad and overlapping bands in the region. Each band increases toward saturated water sorption with different relaxation times. In comparison to conventional methods of generalized 2D correlation spectroscopy and global phase angle mapping, the method proposed in the present study enables the easier visualization of the sequence as a degree of phase angle in the spectrum.

Application of sample-sample two-dimensional correlation spectroscopy to determine the glass transition temperature of poly(ethylene terephthalate) thin films.

The glass transition temperatures (Tg) of poly(ethylene terephthalate) (PET) thin films with different thicknesses are determined by analyzing their in situ reflection-absorption infrared (RAIR) spectra measured over a temperature range of 28 to 84 degrees C. The criterion of standard deviation of the covariance matrices is used as a graphical indicator for the determination of the Tg present in the sample-sample two-dimensional (2D) correlation spectra calculated from the temperature-dependent RAIR spectra. After two data pretreatments of the first derivative of the spectral absorbance versus temperature and the mean normalization over the wavenumbers are sequentially carried out on the RAIR spectra, an abrupt change of the first-derivative correlation spectra with respect to temperature is quickly obtained. It reflects the temperature at which the apparent intensity changes in pertinent absorption bands of PET thin films take place due to the dramatic segmental motion of PET chain conformation. The Tg of the thin PET films is accordingly determined. The results reveal that it decreases with a great dependence on the film thickness and that sample-sample 2D correlation spectroscopy enables one to determine the transition temperature of polymer thin films in an easy and valid way.

Potential of far-ultraviolet absorption spectroscopy as a highly sensitive qualitative and quantitative analysis method for polymer films, part I: classification of commercial food wrap films.

The aim of the present study is to propose a totally new technique for the utilization of far-ultraviolet (UV) spectroscopy in polymer thin film analysis. Far-UV spectra in the 120-300 nm region have been measured in situ for six kinds of commercial polymer wrap films by use of a novel type of far-UV spectrometer that does not need vacuum evaporation. These films can be straightforwardly classified into three groups, polyethylene (PE) films, polyvinyl chloride (PVC) films, and polyvinylidene chloride (PVDC) films, by using the raw spectra. The differences in the wavelength of the absorption band due to the sigma-sigma* transition of the C-C bond have been used for the classification of the six kinds of films. Using this method, it was easy to distinguish the three kinds of PE films and to separate the two kinds of PVDC films. Compared with other spectroscopic methods, the advantages of this technique include nondestructive analysis, easy spectral measurement, high sensitivity, and simple spectral analysis. The present study has demonstrated that far-UV spectroscopy is a very promising technique for polymer film analysis.