Lithium-ion batteries (LIBs) have been deployed in a wide range of energy-storage applications and helped to revolutionize technological development. Recently, a lithium ion battery that uses superconcentrated salt water as its electrolyte has been developed. However, the role of water in facilitating fast ion transport in such highly concentrated electrolyte solutions is not fully understood yet. Here, femtosecond IR spectroscopy and molecular dynamics simulations are used to show that bulk-like water coexists with interfacial water on ion aggregates. We found that dissolved ions form intricate three-dimensional ion−ion networks that are spontaneously intertwined with nanometric water hydrogen-bonding networks. Then, hydrated lithium ions move through bulk-like water channels acting like conducting wires for lithium ion transport. Our experimental and simulation results indicate that water structure-breaking chaotropic anion salts with a high propensity to form ion networks in aqueous solutions would be excellent candidates for water-based LIB electrolytes. We anticipate that the present work will provide guiding principles for developing aqueous LIB electrolytes.

The site-specific incorporation of noncanonical monomers into polypeptides through genetic code reprogramming permits synthesis of bio-based products that extend beyond natural limits. To better enable such efforts, flexizymes (transfer RNA (tRNA) synthetase-like ribozymes that recognize synthetic leaving groups) have been used to expand the scope of chemical substrates for ribosome-directed polymerization. The development of design rules for flexizyme-catalyzed acylation should allow scalable and rational expansion of genetic code reprogramming. Here we report the systematic synthesis of 37 substrates based on 4 chemically diverse scaffolds (phenylalanine, benzoic acid, heteroaromatic, and aliphatic monomers) with different electronic and steric factors. Of these substrates, 32 were acylated onto tRNA and incorporated into peptides by in vitro translation. Based on the design rules derived from this expanded alphabet, we successfully predicted the acylation of 6 additional monomers that could uniquely be incorporated into peptides and direct N-terminal incorporation of an aldehyde group for orthogonal bioconjugation reactions.

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The dendrimer chemistry reported offers a route to synthetic target molecules with spherical shape, well-defined surface chemistries and dimensions that match the size of virus particles. The largest target, a generation 13 dendrimer comprising triazines linked by diamines, is stable across ranges of concentration, pH, temperature, solvent polarity and in the presence of additives. This dendrimer theoretically, presents 16384 surface groups and has a molecular weight exceeding 8.4 million Daltons. Transmission electron and atomic force microscopies, dynamic light scattering, and computation reveal a diameter of approximately 30 nm. The target is synthesized through an iterative divergent approach using a monochlorotriazine macromonomer providing two generations of growth per synthetic cycle. Fidelity in synthesis is supported by evidence from NMR spectroscopy, mass spectrometry, and high pressure liquid chromatography.

The design, synthesis, characterization, and preliminary biological assessment of three dendrimers are reported. All three dendrimers, 1-3, present twelve paclitaxel groups linked by acylation of the 2'-hydroxyl group. The linker for dendrimers 2 and 3 also includes a disulfide. Installation of the paclitaxel group relies on reacting twelve primary amines of a second generation triazine dendrimer, a scaffold available on kilogram scale, with a dichlorotriazine bearing the drug. This dichlorotriazine is available in four steps by (i) reacting paclitaxel with glutaric anhydride, (ii) activating with N-hydroxysuccinimide (NHS), (iii) treating the resulting ester with either 1,3-diaminopropane (for 1) or cystamine (for 2 and 3), and (iv), finally, reacting with cyanuric chloride. After reaction with the dendrimer, the resulting monochlorotriazine groups are reacted with 4-aminomethylpiperidine (AMP) and then a poly(ethylene glycol) (PEG) group of molecular weight 2 kDa. Two different PEG-NHS esters are employed that differ in lability. For 1 and 2, the PEG incorporates an ester-linked succinic acid group. For 3, the PEG incorporates an ether-linked acetic acid group. Both mass spectrometry and 1H NMR spectroscopy prove valuable for determining the final ratios of dendrimer:paclitaxel:AMP:PEG. These values are typically 1:12:12:9. Cytotoxicity of these constructs using an MTT-based assay and PC-3 cells reveals IC(50) values in the low nanomolar range with dithiothreitol and glutathione enhancing the toxicity of the disulfide-containing constructs 2 and 3. Preliminary toxicology assessment of 1 suggests that it is well tolerated in vivo with preferential renal clearance. The elimination half-lives of all of the dendrimers appear shorter than predicted from the previous results. Tumor localization is observed for all the three dendrimers.