Examination of Various Metal Ion Sources for Reducing Nonspecific Zinc finger−Zn2+ Complex Formation in ESI Mass Spectrometry

The formation of zinc finger peptide−Zn2+ complexes in electrospray ionization mass spectrometry (ESI-MS) was examined using three different metal ion sources: ZnCl2, Zn(CH3COO)2, and Zn(OOC(CHOH)2COO). For the four zinc finger peptides (Sp1-1, Sp1-3, CF2II-4, and CF2II-6) that bind only a single Zn2+ in the native condition, electrospray of apo-zinc finger in solution containing ZnCl2 or Zn(CH3COO)2 resulted in the formation of zinc finger−Zn2+ complexes with multiple zinc ions. This result suggests the formation of nonspecific zinc finger−Zn2+ complexes. Zn(tartrate), Zn(OOC(CHOH)2COO),mainly produced specific zinc finger−Zn2+ complexes with a single zinc ion. This study clearly indicates that tartrate is an excellent counter ion in ESI-MS studies of zinc finger−Zn2+ complexes, which prevents the formation of nonspecific zinc finger−Zn2+ complexes

Molecular-Level Interactions between Engineered Materials and Cells

Various recent experimental observations indicate that growing cells on engineered materials can alter their physiology, function, and fate. This finding suggests that better molecular-level understanding of the interactions between cells and materials may guide the design and construction of sophisticated artificial substrates, potentially enabling control of cells for use in various biomedical applications. In this review, we introduce recent research results that shed light on molecular events and mechanisms involved in the interactions between cells and materials. We discuss the development of materials with distinct physical, chemical, and biological features, cellular sensing of the engineered materials, transfer of the sensing information to the cell nucleus, subsequent changes in physical and chemical states of genomic DNA, and finally the resulting cellular behavior changes. Ongoing efforts to advance materials engineering and the cell–material interface will eventually expand the cell-based applications in therapies and tissue regenerations

Toward Visualizing Genomic DNA Using Electron Microscopy via DNA Metallization

Electron microscopy‐based DNA imaging is a powerful tool that provides a high resolution for observing genomic structures involved in biochemical processes. The first method, heavy metal shadow casting, was developed in 1948. Uranyl acetate has been widely used for DNA electron microscopic imaging since the 1960s. However, for this method, scientists must deal with government regulations for the safety and disposal. Additionally, sample preparation is often complicated and time‐consuming. Recently, nanoparticles and nanowires have emerged as a new way of imaging DNA molecules under both transmission and scanning electron microscopes. However, as this technology is still in its early stages, there is room for further development. In this review, heavy metal staining, nanoparticle staining, and nanowire growth for DNA visualization are introduced. The applications of shadow casting and uranyl acetate staining in the visualization of DNA structures and protein–DNA complexes are discussed. Then, nanomaterial‐based DNA staining methods are covered, including electrostatic interactions, DNA chain modification, reducing‐group‐modified DNA ligands and DNA–peptide/protein interactions. This review provides up‐to‐date information on different DNA staining approaches and their applications in DNA studies. Ultimately, it offers a new direction for genome analysis through DNA visualization