This paper reports molecular diffusion behavior in two bolaamphiphile-based organic nanotubes having inner carboxyl groups with different inner dimeters (10 and 20 nm) and wall structures, COOH-ONT 10nm and COOH-ONT 20nm , using imaging fluorescence correlation spectroscopy (imaging FCS). The results were compared to those previously obtained in a similar nanotube with inner amine groups (NH 2 -ONT 10nm ). COOH-ONT 10nm , as with NH 2 -ONT 10nm , were formed from a rolled bolaamphiphile layer incorporating triglycine moieties, whereas COOH-ONT 20nm consisted of four stacks of triglycine-free bolaamphiphile layers. Imaging FCS measurements were carried out for anionic sulforhodamine B (SRB), zwitterionic/cationic rhodamine B (RB), and cationic rhodamine-123 (R123) diffusing within ONTs (1−9 μm long) at different pH (3.4−8.4) and ionic strengths (1.6−500 mM). Diffusion coefficients (D) of these dyes in the ONTs were very small (0.01−0.1 μm 2 /s), reflecting the significant contributions of molecule-nanotube interactions to diffusion. The D of SRB was larger at higher pH and ionic strength, indicating the essential role of electrostatic repulsion that was enhanced by the deprotonation of the inner carboxyl groups. Importantly, the D of SRB was virtually independent of nanotube inner diameter and wall structure, indicating the diffusion of the hydrophilic molecule was controlled by short time scale adsorption/desorption processes onto the inner surface. In contrast, pH effects on D were less clear for relatively hydrophobic R123 and RB, suggesting the significant contributions of non-Coulombic interactions. Interestingly, the diffusion of these molecules in COOH-ONT 20nm was slower than in COOH-ONT 10nm . Slower diffusion in COOH-ONT 20nm was attributable to relatively efficient partitioning of the hydrophobic dyes into the bolaamphiphile layers, which was reduced in COOH-ONT 10nm due to the stabilization of its layer by polyglycine-II-type hydrogen bonding networks. These results show that, by tuning the bolaamphiphile structures and their intermolecular interactions, unique environments can be created within the nanospaces for enhanced molecular separations and reactions.

Viruses are a prolific force able to infect any form of life on the planet, including plants. Around the world, plant viruses cause considerable yield loss in many agriculture crops every year. Antiviral immunity in plants is mediated by RNA silencing and RNA decay mechanisms, which proceed as follows: once a virus inserts its genetic material into a cell, dicer‐like ribonucleases (DCLs) detect the viral RNA and fragment it into small interfering RNAs (siRNAs). These RNA fragments are then bound by Argonaute proteins and form an RNA‐induced silencing complex (RISC). The RISC binds to complementary sequences of the viral RNA and remains bound, thus deactivating or degrading the fragment by enzymatically cleaving the RNA. siRNA antiviral RNA silencing is utilized for acute or cellular antiviral defense, but it also plays a role in systemic antiviral defense. In plants the systemic silencing mechanism is mediated by enzymes called RNA‐dependent RNA polymerases (RDR) that synthesize double stranded RNA (dsRNA) from single strand RNA. These dsRNAs are then processed through the same siRNA‐silencing pathway, producing new siRNAs that can silence viral genes. The supplementary siRNAs can then be transported between cells through the plants’ vasculature and the plasmodesmata. This leads to systemic treatment and defense in the plant. Though the core genetic components of antiviral RNA silencing have been determined, additional components remain to be identified and characterized. For example, the A. thaliana genome encodes six RDR genes. It is known that RDR1 and RDR6 have major roles in antiviral RNA silencing and that RDR2 mediates biogenesis of cellular siRNAs. However, the role of the RDR3, RDR4, and RDR5 genes is not known. Though single mutants of RDR3, RDR4, and RDR5, have been constructed, double or triple mutants cannot be obtained by tDNA mutation because all three genes are linked together on the second chromosome. Our hypothesis was that RDR3 and RDR4 can be inactivated by site‐specific genome editing using the CRISPR/Cas9 technique to develop mutants lacking these genes. Further experiments show the expression of the Cas9 protein in the second generation, confirming transformation of A. thaliana proteins and RNA. We expect that creating this sextuple mutant, in which all six RDR genes are deactivated, allows the continued exploration of the role of RDRs in antiviral silencing. The RDR3 and RDR4 inactive mutants will also facilitate the necessary positive and negative control mutants needed for future analytical studies. Support or Funding Information Undergraduate Creative Activities and Research Experience Project, funded by the PepsiQuasi Endowment and Union Bank & Trust. National Institute of Health (R01GM120108). Institute of Agriculture and Natural Resources, Agricultural Research Division, Undergraduate Student Research Program CRISPR single guide RNAs. A) Target Sites and sgRNAs in RDR3a an dRDR3b found using CCTOP (Stemmer et al. 2015). Small guide RNAs are the target sites minus the PAM colored i...

Bart Bartlett, a professor of chemistry at the University of Michigan, was an ACS Scholar from 1998 to 2000, during his junior and senior years of college at Washington University in St. Louis. In this interview, Bartlett talks about what inspired him to go into chemistry and the importance of having an alumni network. This interview was edited for length and clarity. What motivated you to go into chemistry? I got into chemistry largely because I had a good experience with chemistry in high school. I had a really good high school chemistry teacher, and I liked the subject. The summer after my junior year, I started doing research at the Washington University School of Medicine with the Department of Genetics. There’s a program called the Young Scientist Program. It was instrumental in getting me to see how a lab functioned. Unlike in a high school lab class where you