Identification of a Weak Interaction between the Spin-Only 4f-Electronic System of Trivalent Gd Ion and a Photoexcited Cyclic π Electronic System.

An electronic interaction between the spin-only 4f-electronic system and the photoexcited π cyclic system has been identified in the anionic bis(phthalocyaninato)gadolinium(III) complex [Pc2Gd]- by using variable-temperature variable-magnetic-field magnetic circular dichroism (VTVH MCD). Two positive MCD A-term patterns, corresponding to the QH and QL absorption bands, were observed to increase in intensity as the temperature decreased, indicating a ferromagnetic-type interaction between spin angular momentum S of the 4f system and orbital angular momentum L of the photoexcited π system. A theoretical model incorporating the S-L interaction constant CSL was fitted to the VTVH MCD spectra, confirming the presence of a weak interaction, whose intensity was determined as CSL = 0.27 cm-1 for QL and CSL = 0.02 cm-1 for QH. Ab initio calculations using the RASSCF and RASSI methods revealed that the inclusion of the excited state calculations with the spin multiplicity (2S + 1) of 6 was crucial for assigning ΔSL and CSL values. This underscores the essential role of the 6PJ term in accurately modeling the S-L interaction in [Pc2Gd]-.

Establishment of a novel cell line, CHO-MK, derived from Chinese hamster ovary tissues for biologics manufacturing.

Chinese hamster ovary (CHO) cells are widely used as a host for producing recombinant therapeutic proteins due to advantages such as human-like post-translational modification, correct protein folding, higher productivity, and a proven track record in biopharmaceutical development. Much effort has been made to improve the process of recombinant protein production, in terms of its yield and productivity, using conventional CHO cell lines. However, to the best of our knowledge, no attempts have been made to acquire new CHO cell lines from Chinese hamster ovary. In this study, we established and characterized a novel CHO cell line, named CHO-MK, derived from freshly isolated Chinese hamster ovary tissues. Some immortalized cell lines were established via sub-culture derived from primary culture, one of which was selected for further development toward a unique expression system design. After adapting serum-free and suspension culture conditions, the resulting cell line exhibited a considerably shorter doubling time (approximately 10 h) than conventional CHO cell lines (approximately 20 h). Model monoclonal antibody (IgG1)-producing cells were generated, and the IgG1 concentration of fed-batch culture reached approximately 5 g/L on day 8 in a 200-L bioreactor. The cell bank of CHO-MK cells was prepared as a new host and assessed for contamination by adventitious agents, with the results indicating that it was free from any such contaminants, including infectious viruses. Taking these findings together, this study showed the potential of CHO-MK cells with a shorter doubling time/process time and enhanced productivity in biologics manufacturing.

Construction of high-throughput magnetic circular dichroism measurement system and its application to research on magnetic and optical properties of phthalocyanine complexes.

Magnetic circular dichroism (MCD) spectroscopy is a powerful method for evaluating the electronic structure and magnetic and optical properties of molecules. In particular, MCD measurements have been performed on phthalocyanines and porphyrins with various central metal ions, axial ligands, and substituents to elucidate their properties. It is essential to develop a robust high-throughput technique to perform these measurements comprehensively and efficiently. However, MCD spectroscopy requires very high optical quality for each component of the instrument, and even slight cell distortions can impair the baseline flatness. Consequently, when versatility and data quality are important, an optical system designed for a microplate reader is not suitable for the MCD spectrometer. Therefore, in this study, we develop a new magnetic flow-through cell and combine it with an existing CD spectrometer and autosampler to construct a high-throughput system. The effectiveness and performance of this new system are then evaluated. In addition, based on the MCD and absorption spectra of various phthalocyanine complexes, the effects of substituents and solvents on their magnetic and optical properties and the causes of these effects are discussed. The results demonstrate that this system is effective for the evaluation of the physicochemical properties of various phthalocyanine complexes.