Recent advances in optical diagnosis of oral cancers: Review and future perspectives

Optical diagnosis techniques offer several advantages over traditional approaches, including objectivity, speed, and cost, and these label‐free, noninvasive methods have the potential to change the future workflow of cancer management. The oral cavity is particularly accessible and, thus, such methods may serve as alternate/adjunct tools to traditional methods. Recently, in vivo human clinical studies have been initiated with a view to clinical translation of such technologies. A comprehensive review of optical methods in oral cancer diagnosis is presented. After an introduction to the epidemiology and etiological factors associated with oral cancers currently used, diagnostic methods and their limitations are presented. A thorough review of fluorescence, infrared absorption, and Raman spectroscopic methods in oral cancer diagnosis is presented. The applicability of minimally invasive methods based on serum/saliva is also discussed. The review concludes with a discussion on future demands and scope of developments from a clinical point of view. © 2015 Wiley Periodicals, Inc. Head Neck 38 : E2403–E2411, 2016     

Investigating phase separation in amorphous solid dispersions via Raman mapping

The bioavailability of poorly-water-soluble active pharmaceutical ingredients (APIs) can be significantly improved by so-called amorphous solid dispersions (ASDs). However, the long-term stability of ASDs might be impaired by API recrystallization and/or amorphous phase separation (APS). So far, no methods have been reported to quantify APS in ASDs. In this work, phase-separation kinetics as well as the compositions of the two amorphous phases evolving due to APS were quantitatively determined for the first time using confocal Raman spectroscopy. Raman spectra were evaluated via non-linear multivariate Indirect Hard Modeling and verified by differential scanning calorimetry and hot-stage microscopy. APS in water-free ASDs of ibuprofen and poly (DL-lactic-co-glycolic acid) was investigated considering the influence of temperature and polymer architecture (linear vs. star-shaped). Water absorbed at 40?°C and 75% relative humidity (RH) promotes APS which was quantified for formulations of felodipine/poly(vinyl pyrrolidone) and ibuprofen/poly(vinyl pyrrolidone).     

Toward the interpretation of the combined effect of size and body weight on the tribological performance of total knee prostheses

Purpose

The research questions of the present study were: (1) Is total knee prosthesis wear behaviour influenced by implant size, body weight and their combined effect? (2) Are these findings significant and helpful from a clinical point of view?

Methods

Two very different sizes of the same total knee prosthesis (TKP), previously tested with ISO 14243 parameters, were tested on a knee simulator for a further two million cycles using a modified ISO 14243 load waveform. Roughness examination was performed on the metallic components. Gravimetric and micro-Raman spectroscopic analyses were carried out on the polyethylene inserts.

Results

The average volumetric mass loss was 69 ± 3 mm³ and 88 ± 4 mm³ for smaller and bigger size, respectively. Bigger TKPs are little influenced by an increased load, while the wear trend of the smaller TKP showed a redoubled slope, and more significant morphology changes were observed. However, the two sizes seem to behave similarly when subjected to a load increase of 15 %; the slope of the volumetric mass loss trend was comparable for the two sets of inserts, which did not appear significantly different also at the molecular level. Roughness average parameters of the lateral femoral condyle support this evidence.

Conclusions

It can be asserted that the body weight and implant size are relevant to the understanding of TKP wear behaviour. A post-implantation body weight increase in a patient with smaller knee dimensions could results in more critical effects on prosthesis long-term performance.     

In-line solid state prediction during pharmaceutical hot-melt extrusion in a 12 mm twin screw extruder using Raman spectroscopy

The aim of this research was to use Raman spectroscopy for the in-line monitoring of the solid state of materials during pharmaceutical hot-melt extrusion in the die head of a 12 mm (development scale) twin-screw extruder during formulation development.A full factorial (mixed) design was generated to determine the influence of variations in concentration of Celecoxib (CEL) in Eudragit® E PO, three different screw configurations and varying barrel temperature profiles on the solid state, ‘melt temperature’ and die pressure of continuously produced extrudates in real-time. Off-line XRD and DSC analysis were used to evaluate the suitability of Raman spectroscopy for solid state predictions. First, principal component analysis (PCA) was performed on all in-line collected Raman spectra from the experimental design. The resulting PC 1 versus PC 2 scores plot showed clustering according to solid state of the extrudates, and two classes, one class where crystalline CEL is still present and a second class where no crystalline CEL was detected, were found. Then, a soft independent modelling of class analogy (SIMCA) model was developed, by modelling these two classes separately by disjoint PCA models. These two separate PCA models were then used for the classification of new produced extrudates and allowed distinction between glassy solid solutions of CEL and crystalline dispersions of CEL. All extrudates were classified similarly by Raman spectroscopy, XRD and DSC measurements, with exception of the extrudates with a 30% CEL concentration extruded at 130 °C. The Raman spectra of these experiments showed bands which were sharper than the amorphous spectra, but broader than the crystalline spectra, indicating the presence of CEL that has dissolved into the matrix and CEL in its crystalline state. XRD and DSC measurements did not detect this. Modifications in the screw configuration did not affect the solid state and did not have an effect on the solid state prediction of new produced extrudates.Secondly, the influence of variations in die pressure on the Raman spectra was examined. The applied drug concentration, processing temperature and feeder performance influence the die pressure, which is reflected in the Raman spectra as a change in spectral intensity. When applying PCA on the raw spectra from the experimental design, the first principal component describes the influence of die pressure on the spectra, which was seen as a decrease in Raman intensity of the whole spectrum when the pressure in the sample increased. Clustering according to processing temperature was found, although the temperature in the die remained constant, indicating that a difference in viscosity, resulting in a changed die pressure, was detected. When the feeder was stopped, the score values of the first principal component almost simultaneously decreased, and only stabilized once the die pressure became stable. Since Raman spectra collected in the extrusion die are influenced by changes in die pressure, disturbances upstream of the extrusion process can be observed and identified in the Raman measurements.     

TLC-SERS联用法检测降糖中成药中添加的格列类药品

目的：研究降糖中成药中非法添加格列类药品的表面增强拉曼光谱（ surface enhanced Raman spectroscopy , SERS）检测方法。方法利用薄层色谱法将待检成分与中药基质进行简单分离,采用表面增强拉曼光谱技术对薄层板上的微量物质进行检测。通过摸索模拟阳性样品中格列类药品的SERS检测条件,建立可用于降糖中成药中非法添加物的检测方法。结果采用有机溶剂DMF制备所得的银溶胶可以获得较好的格列类药物SERS图谱。结论该研究所建立的TLC与SERS联用方法检测简便、快速、经济,可用于降糖中成药中非法添加格列类药品的快速检测。     

Study of the Solid-State Synthesis of Nickel Ferrite (NiFe2O4) by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Raman Spectroscopy

Spinel ferrite compounds continue to receive a lot of attention due to their unique properties. Among the numerous synthesis routes existing, the solid-state method was applied for the production of nickel ferrite, by introducing the use of a quartz vial. A mixture of nickel oxide (NiO) and hematite (Fe₂O₃) was ground and vacuum-sealed in the vial and different thermal treatment programs were tested. The resulting particles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectroscopy. For temperatures, below 1000 °C, the solid-state reaction is not complete as nickel oxide (NiO) and hematite (Fe₂O₃) are still present. The reaction time is a decisive parameter for the morphology of the particles obtained. If, for different reaction times, the particle size distribution is always between 0.3 and 1.7 µm, a longer reaction time leads to the formation of dense, interconnected clusters of particles. Optimal parameters to synthesize a pure phase of spherical nickel ferrite were sought and found to be a reaction temperature of 1000 °C for 72 h.     

Colored Tattoo Ink Screening Method with Optical Tissue Phantoms and Raman Spectroscopy

Due to the increasing popularity of tattoos among the general population, to ensure their safety and quality, there is a need to develop reliable and rapid methods for the analysis of the composition of tattoo inks, both in the ink itself and in already existing tattoos. This paper presents the possibility of using Raman spectroscopy to examine tattoo inks in biological materials. We have developed optical tissue phantoms mimicking the optical scattering coefficient typical for human dermis as a substitute for an in vivo study. The material employed herein allows for mimicking the tattoo-making procedure. We investigated the effect of the scattering coefficient of the matrix in which the ink is located, as well as its chemical compositions on the spectra. Raman surface line scanning has been carried out for each ink in the skin phantom to establish the spatial gradient of ink concentration distribution. This ensures the ability to detect miniature concentrations for a tattoo margin assessment. An analysis and comparison of the spectra of the inks and the tattooed inks in the phantoms are presented. We recommend the utilization of Raman spectroscopy as a screening method to enforce the tattoo ink safety legislations as well as an early medical diagnostic screening tool.     

Structural Features of Y2O2SO4 via DFT Calculations of Electronic and Vibrational Properties

The traditional way for determination of molecular groups structure in crystals is the X-Ray diffraction analysis and it is based on an estimation of the interatomic distances. Here, we report the analysis of structural units in Y₂O₂SO₄ using density functional theory calculations of electronic properties, lattice dynamics and experimental vibrational spectroscopy. The Y₂O₂SO₄ powder was successfully synthesized by decomposition of Y₂(SO₄)₃ at high temperature. According to the electronic band structure calculations, yttrium oxysulfate is a dielectric material. The difference between the oxygen–sulfur and oxygen–yttrium bond nature in Y₂O₂OS₄ was shown based on partial density of states calculations. Vibrational modes of sulfur ions and [Y₂O₂²⁺] chains were obtained theoretically and corresponding spectral lines observed in experimental Infrared and Raman spectra.