Development of in-situ Raman diagnosis technique of eosinophil esophagitis.

The spectra of the live tissue with blood flow measured with 785 nm-excitation light showed a very weak signal due to hemoglobin (Hb). It suggested the possibility to detect eosinophil accumulation in the tissue with the 785 nm-excitation light. The excitation wavelength of 633 nm induced strong fluorescence of sapphire glass that is a material of the ball lens of BHRP (Ball lens top hollow optical fiber Raman probe). On the other hand, the previous study suggested that eosinophil including eosinophil peroxidase (EPO) that showed a strong resonance Raman effect with 633 nm-excitation light. The purpose of the present study is to collect basic information and to evaluate the viability of Raman spectroscopic analysis for the detection of eosinophil accumulation in the live esophagus. BHRP with a sapphire ball lens with 500 µm diameter was applied for measurement of live esophagus tissue of a mouse. In this study, Raman spectra of eosinophil were measured with 633 and 785 nm-excitation. The Raman spectra of eosinophil showed a strong contribution of EPO, suggested that a heme chromophore in EPO had pre-resonance enhancement via Q band with the 785 nm-excitation light. Principal component analysis (PCA) is applied for the analysis of Raman spectra of eosinophil, erythrocyte and other granulocytes. Eosinophil was successfully discriminated from other blood cells in the PCA score plots built for the datasets of the spectra measured with 633 and 785 nm-excitation wavelengths. Consequently, our study demonstrates that Raman spectroscopy with 785 nm-excitation had high viability for in situ analysis of eosinophilic esophagitis (EoE).

A Peptoid with Extended Shape in Water.

The term "peptoids" was introduced decades ago to describe peptide analogues that exhibit better physicochemical and pharmacokinetic properties than peptides. Oligo(N-substituted glycine) (oligo-NSG) was previously proposed as a peptoid due to its high proteolytic resistance and membrane permeability. However, oligo-NSG is conformationally flexible, and ensuring a defined shape in water is difficult. This conformational flexibility severely limits the biological application of oligo-NSG. Here, we propose oligo(N-substituted alanine) (oligo-NSA) as a peptoid that forms a defined shape in water. The synthetic method established in this study enabled the first isolation and conformational study of optically pure oligo-NSA. Computational simulations, crystallographic studies, and spectroscopic analysis demonstrated the well-defined extended shape of oligo-NSA realized by backbone steric effects. This new class of peptoid achieves the constrained conformation without any assistance of N-substituents and serves as a scaffold for displaying functional groups in well-defined three-dimensional space in water, which leads to effective biomolecular recognition.