Foreword

This “Current Topics” is designed for a wide variety of readers (including students and pharmacy residents) of the Chemical and Pharmaceutical Bulletin (CPB) who are working in the basic and clinical fields of the pharmaceutical sciences as it will feature present-day topics in the field of analytical chemistry. Analytical chemistry is a kind of chemistry that deals with the chemical and physical methodologies of the separation, isolation, and detection of chemical substances. Student pharmacists in Japan generally learn analytical chemistry in their first or second year of studies as one of the fundamentals of chemistry or as a part of the physical pharmaceutical sciences. In contrast, research in analytical chemistry is characterized by its interdisciplinary aspects. Therefore, it is recommended to provide high quality information on analytical chemistry research to students and graduates who feel that there are some gaps between their education and their research in the field of analytical chemistry.

To solve this issue, six topics have been reviewed from basic to practical or clinical subjects that include: vesicle behaviors, lipidomics, disease models, supercritical fluid techniques, antibody–drug conjugate analysis, and immunochromatography. All of them are based on the fundamentals of analytical chemistry. The application of analytical chemistry is not only limited to the pharmaceutical sciences, but it can also be expanded to the industrial, agricultural, and environmental sciences, and this “Current Topics” is particularly focused on recent advances in analytical chemistry in both the fields of biology and medicine.

The first review, entitled “Molecular Transformation for Self-reproducing Vesicles and Underlying Analysis Methods,” has been written by Prof. Taro Toyota et al. at the University of Tokyo. The authors summarize the self-reproduction of vesicles driven by molecular transformation and applicable methods to this phenomenon. The methods shown are: Fourier-transform IR spectroscopy (FTIR), turbidity (optical density), gel electrophoresis, fluorescence resonance energy transfer (FRET), flow cytometry, optical microscopy, HPLC with evaporative light scattering detection, ³¹P-NMR, transmission electron microscopy (TEM), dynamic light scattering (DLS), and differential scanning calorimetry (DSC). In the last section, the authors also discuss the origin of life.

The second review, entitled “Characterization of the Structural Diversity and Structure-Specific Behavior of Oxidized Phospholipids by LC-MS/MS,” has been summarized by Dr. Ryohei Aoyagi, Prof. Makoto Arita, and their colleagues at Keio University and RIKEN. The authors review the generation, analytical methods, and physiological roles of oxidized phospholipids (OxPLs) in health and disease. Several modes of mass spectrometry-based lipidomics and their application to the determination of OxPLs are superbly introduced in order to explore their structures and functions in both fields of biology and medicine.

The third review, entitled “Carcinogenesis Models Using Small Fish,” was written by Drs. Takashi Kawasaki and Yuki Shimizu at the National Institute of Advanced Industrial Science and Technology (AIST). Recent technological advances in carcinogenesis models have been summarized with a special focus on small fish that have indispensable characteristic advantages including some transparency for in vivo imaging, genetic manipulability of ortholog genes of humans, and ease of handling.

The fourth review, entitled “Emerging Separation Techniques in Supercritical Fluid Chromatography,” was written by Dr. Kazuhiro Yamamoto et al. of my laboratory at Tokyo University of Pharmacy and Life Sciences. In this review, the authors describe newly developed or improved techniques related to SFC separation that include: new column stationary phases, microfluidics, two-dimensional separation, and gas-liquid separation.

The fifth review, entitled “Recent Advances in Drug–Antibody Ratio Determination of Antibody–Drug Conjugates,” has been summarized by Drs. Yutaka Matsuda and Brian A. Mendelsohn at Ajinomoto Co., Inc. and Ajinomoto Bio-Pharma Services, respectively. The authors effectively review the recent progress of analytical methods for the determination of drug–antibody ratios of antibody–drug conjugates, providing guidelines for the quality control to manufacture antibody–drug conjugates.

The sixth review, entitled “Immunochromatography—Application Example and POCT Type Genetic Testing,” was written by Drs. Isami Tsuboi and Katsuhiro Iinuma at BML Medical Works Inc. and BML Inc., respectively. The authors describe recent topics of membrane-based rapid test reagents including the highly sensitive detection of immunochromatography by a silver amplification method and a time resolved fluorescence method as well as the isolation of nucleic acids by a silica particle-containing membrane filter for PCR testing such as for coronavirus disease 2019 (COVID-19).

Most analytical chemists prefer conducting basic research in the measurement sciences, and as such little attention has been paid to the practical application of these established methods. This idea is understandable and reasonable as basic research can sometimes break through the dead rocks in natural sciences, leading to new findings. At the same time, it would be worthy to improve on established methods to a certain extent to help make them applicable to new analytes. The latter idea may affect the above-mentioned gap between education and research in analytical chemistry where the former mainly deals with established methods. This “Current Topics” contains findings from both fundamental and practical research studies with detailed explanations by the excellent authors. I would like to express my special thanks to all of the authors for their kind acceptance of my request for their significant contributions to this issue of the CPB.