Simple chitin-based cell culture platform for production of biopharmaceuticals.

OBJECTIVES: Gene therapy using viral vectors and antibody-based therapies continue to expand within the pharmaceutical market. We evaluated whether Cellhesion® VP, a chitin-based material, can be used as 3D culture platform for cell lines used for the production of antibodies and viral vectors. RESULTS: The results of Cell Counting Kit-8 assay and LDH assay revealed that Cellhesion® VP had no adverse effect to Human Embryonic Kidney (HEK) 293, A549 and Chinese hamster ovary (CHO) DG44-Interferon-ß (IFN) cells. Cell growth analyses showed that Cellhesion® VP supported the 3D culture of HEK293, A549 and CHO DG44- IFN-ß cells with a spherical morphology. Importantly, subculture of these cell lines on Cellhesion® VP was easily performed without trypsinization because cells readily transferred to newly added scaffold. Our data also suggest that CHO DG44-IFNß, cultured on Cellhesion® VP secreted IFNß stably and continuously during the culture period. CONCLUSIONS: Cellhesion® VP provides a simple and streamlined expansion culture system for the production of biopharmaceuticals.

Atomically Precise Alloy Nanoclusters.

Invited for the cover of this issue is the group of Yuichi Negishi at Tokyo University of Science. The image depicts the alloy nanoclusters reported in this review. Read the full text of the article at 10.1002/chem.202001877.

Atomically Precise Alloy Nanoclusters.

Metal nanoclusters (NCs) have a particle size of about one nanometer, which makes them the smallest unit that can give a function to a substance. In addition, metal NCs possess physical and chemical properties that are different from those of the corresponding bulk metals. Metal NCs with such characteristics are expected to be important for use in nanotechnology. Research on the precise synthesis of metal NCs and elucidation of their physical/chemical properties and functions is being actively conducted. When metal NCs are alloyed, it is possible to obtain further various electronic and geometrical structures and functions. Thus, research on alloy NCs has become a hot topic in the study of metal NCs and the number of publications on alloy NCs has increased explosively in recent years. Such publications have provided much insight into the effects of alloying on the electronic structure and function of metal NCs. However, the rapid increase in knowledge has made it difficult for researchers (especially those new to the field) to grasp all of it. Therefore, in this review, we summarize the reported chemical composition, geometrical structure, electronic structure, and physical and chemical properties of Aun-x Mx (SR)m , Agn-x Mx (SR)m , Aun-x Mx (PR3 )l (SR)m , and Agn-x Mx (PR3 )l (SR)m (Au=gold, Ag=silver, M=heteroatom, PR3 =phosphine, and SR=thiolate) NCs. This review is expected to help researchers understand the characteristics of alloy NCs and lead to clear design guidelines to develop new alloy NCs with intended functions.

Elucidating ligand effects in thiolate-protected metal clusters using Au24Pt(TBBT)18 as a model cluster.

2-Phenylethanethiolate (PET) and 4-tert-butylbenzenethiolate (TBBT) are the most frequently used ligands in the study of thiolate (SR)-protected metal clusters. However, the effect of difference in the functional group between these ligands on the fundamental properties of the clusters has not been clarified. We synthesized [Au24Pt(TBBT)18]0, which has the same number of metal atoms, number of ligands, and framework structure as [Au24Pt(PET)18]0, by replacing ligands of [Au24Pt(PET)18]0 with TBBT. It was found that this ligand exchange is reversible unlike the case of other metal-core clusters. A comparison of the geometrical/electronic structure and stability of the clusters between [Au24Pt(PET)18]0 and [Au24Pt(TBBT)18]0 revealed three things with regard to the effect of ligand change from PET to TBBT on [Au24Pt(SR)18]0: (1) the induction of metal-core contraction and Au-S bond elongation, (2) no substantial effect on the HOMO-LUMO gap but a clear difference in optical absorption in the visible region, and (3) the decrease of stabilities against degradation in solution and under laser irradiation. By using these two clusters as model clusters, it is expected that the effects of the structural difference of ligand functional-groups on the physical properties and functions of clusters, such as catalytic ability and photoluminescence, would be clarified.