Foreword

Electrochemical analysis, which measures electrode potentials and electron transfers occurring during redox reactions as voltage and current, respectively, has outstanding advantages such as selectivity, high sensitivity, rapid measurement, simple operation, high reproducibility, long-term stability, easy miniaturization, low cost, low power consumption, and can be used both on-site and for in situ analyses. Therefore, various electrochemical analyses have been widely applied to many fields including disease diagnosis, drug quality, environmental monitoring, food safety, agricultural engineering, and even public safety. Electrochemical analysis has also been, needless to say, used to make contributions in the fields of the pharmaceutical sciences. This Current Topics section in this issue of Chem. Pharm. Bull. contains one communication and four regular articles describing the latest research regarding electrochemical analysis useful for the pharmaceutical sciences.

The communication, entitled “Electrochemical Characterization of a Novel Organoelectrocatalyst, 7-Azabicyclo[2.2.1]heptan-7-ol (ABHOL), and Its Application to Electrochemical Sensors” has been written by Dr. Masaki Toda, Dr. Katsuhiko Sato, and collaborators from Tohoku University and Tohoku Medical and Pharmaceutical University. A blood glucose level is frequently measured in clinical diagnosis and monitoring of diabetes mellitus. The authors developed a non-enzymatic electrochemical sensor using ABHOL, a highly active hydroxylamine catalyst, and its application to glucose sensing. The advantages of ABHOL as an electrochemical probe were demonstrated in comparison with the electro-oxidation properties of the studied organoelectrocatalysts.

The first regular article, entitled “Evaluation of Antibiotic Penicillin G Activities Based on Electrochemical Measurement of a Tetrazolium Salt” has been written by Mr. Hikaru Ikeda, Prof. Hiroshi Shiigi, and collaborators from Osaka Metropolitan University, EC Frontier Co., and Green Chem. Inc. A simple method to assess viable bacterial counts is useful for drug susceptibility testing. The authors developed a novel electrochemical method using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay to assess bacterial viability during drug susceptibility testing with penicillin G (PCG). The residual amount of MTT in the bacterial suspension was electrochemically measured with and without PCG, and the effect of PCG based on the difference in MTT reduction was evaluated. The effectiveness of the electrochemical method for drug susceptibility testing was verified by comparison with conventional turbidity and MTT colorimetric methods.

The second regular article, entitled “Construction of Biosensing System for Glycated Albumin Using an Electron Transfer Peptide-Modified Protein Probe” was written by Mr. Michiru Ito and Prof. Kazuharu Sugawara at Maebashi Institute of Technology. Glycated albumin (GA) reflects a shorter-term glycemic control state than glycated hemoglobin (HbA1c). The authors developed a voltammetric system capable of sensing GA for the early detection of diabetes mellitus. A protein probe of electroactive acetylated H₆Y₄C combined with wheat germ agglutinin (Ac-H₆Y₄C-WGA) was synthesized to electrochemically sense GA. Their results demonstrated that the Ac-H₆Y₄C-WGA-based sensing system could be a sensitive and rapid method to detect GA in human serum samples.

The third regular article, entitled “Electrochemical Analysis for Total Alkalinity of Water by the Measurement of Cathodic Prepeak of Quinone Caused by Surplus Acid” was written by our research group at Tokyo University of Pharmacy and Life Sciences. Determination of total alkalinity is routinely conducted as a part of standard water quality estimation. We developed an electrochemical analysis, coupled with the concept of back neutralization titration and the measurements of the cathodic prepeak height of quinone caused by surplus H₂SO₄ after neutralization, for determining inorganic bases such as NaOH and Na₂CO₃. We demonstrated that the present electrochemical analysis with accuracy and precision could be applied to determine the total alkalinity of water samples.

The fourth regular article, entitled “Development of a Potential-Modulated Electrochemiluminescence Measurement System for Selective and Sensitive Determination of the Controlled Drug Codeine” was written by Dr. Fumiki Takahashi and collaborators from Shinshu University, Nihon University, and RIKEN SPring-8 Center. Codeine has a high risk of abuse as a recreational drug because of its extensive distribution as an OTC drug. Therefore, sensitive and selective screening methods for codeine are crucial in forensic analytical chemistry. The authors developed a highly sensitive analytical technique for determining codeine, combined with potential modulation and electrochemiluminescence (PM-ECL). By the present PM-ECL, codeine was selectively determined from other compounds in medications and showed good linearity with a low detection limit (150 ng/mL).

I believe these articles in this Current Topics section will be useful in demonstrating that electrochemical analysis is a significant and practical strategy in the fields of the pharmaceutical sciences. Finally, I would like to express my special thanks to all of the authors for their significant contributions to this special issue of Chem. Pharm. Bull.