Image fusion of IR and optical microscopy for mapping of biomolecules in tissue

An optical photothermal infrared investigation of lymph nodal metastases of oral squamous cell carcinoma

In this study, optical photothermal infrared (O-PTIR) spectroscopy combined with machine learning algorithms were used to evaluate 46 tissue cores of surgically resected cervical lymph nodes, some of which harboured oral squamous cell carcinoma nodal metastasis. The ratios obtained between O-PTIR chemical images at 1252 cm-1 and 1285 cm-1 were able to reveal morphological details from tissue samples that are comparable to the information achieved by a pathologist's interpretation of optical microscopy of haematoxylin and eosin (H&E) stained samples. Additionally, when used as input data for a hybrid convolutional neural network (CNN) and random forest (RF) analyses, these yielded sensitivities, specificities and precision of 98.6 ± 0.3%, 92 ± 4% and 94 ± 5%, respectively, and an area under receiver operator characteristic (AUC) of 94 ± 2%. Our findings show the potential of O-PTIR technology as a tool to study cancer on tissue samples.

Tissue discrimination in head and neck cancer using image fusion of IR and optical microscopy

A regression-based fusion algorithm has been used to merge hyperspectral Fourier transform infrared (FTIR) data with an H&E image of oral squamous cell carcinoma metastases in cervical lymphoid nodal tissue. This provides insight into the success of the ratio of FTIR absorbances at 1252 cm-1 and 1285 cm-1 in discriminating between these tissue types. The success is due to absorbances at these two wavenumbers being dominated by contributions from DNA and collagen, respectively. A pixel-by-pixel fit of the fused spectra to the FTIR spectra of collagen, DNA and cytokeratin reveals the contributions of these molecules to the tissue at high spatial resolution.

Far-field super-resolution chemical microscopy

Far-field chemical microscopy providing molecular electronic or vibrational fingerprint information opens a new window for the study of three-dimensional biological, material, and chemical systems. Chemical microscopy provides a nondestructive way of chemical identification without exterior labels. However, the diffraction limit of optics hindered it from discovering more details under the resolution limit. Recent development of super-resolution techniques gives enlightenment to open this door behind far-field chemical microscopy. Here, we review recent advances that have pushed the boundary of far-field chemical microscopy in terms of spatial resolution. We further highlight applications in biomedical research, material characterization, environmental study, cultural heritage conservation, and integrated chip inspection.

The analysis of glass from portable electronic devices and glass accessories using µ-XRF for forensic investigations

In this study, glass from 30 different portable electronic devices (PED) screens, 15 screen protectors (SP), and 3 brands of liquid glass (LG) were analyzed using a µ-XRF instrument equipped with two silicon drift detectors (SDD). Additional analysis of six fragments, all originating from the same PED and SP screen, assessed the elemental homogeneity within a single glass source. Examinations of the 30 PEDs and the majority of the SP screens revealed spectra with low sodium and high potassium, which is likely due to the ion exchange process at the surface during the glass manufacturing process. The absence of calcium in the XRF spectra was also characteristic of PED formulations. Initial spectral overlay examinations classified the PED and SP samples into major groups based on their distinctive elemental profiles (5 PED groups, 4 SP groups). Further discrimination of within-group samples was possible when considering reproducible differences in signal intensities (discrimination 98.4 % PED, 98.1 % SP). Additionally, a 3 s (3 % Relative Standard Deviation, RSD) comparison criterion produced the lowest false exclusion rates among same-source fragments (3.3 % PED, 0.8 % SP) while maintaining a high discrimination power among different-source fragments (98.4 % PED, 100 % SP). Same source PED and SP samples resulted in low variability within most elements examined (< 8 % RSD), except for potassium. An experimental threshold established from the quantitative metric of spectral similarity, spectral contrast angle (SCA) ratio of same-source and different-source datasets, produced false exclusion and false inclusion rates of 4 % or 0.95 % for PED and SP fragments, respectively. Spectra of just the liquid glass residues indicated some major elements present but the effect of these elements in PED fragments treated with liquid glass was not significant. This study provides a preliminary understanding of the elemental composition of modern PED glasses and their accessories and the discrimination capability of µ-XRF for forensic comparisons.