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Understanding the nanoparticle deposition process is important for predicting the transport and fate of nanoparticles in natural and engineered aquatic environments. Traditional methods for deposit...

The ability to rapidly and accurately detect water toxicity is crucial for monitoring water quality and assessing toxic risk, but such detection remains a great challenge. Here, we present a plasmonic nanomechanical sensing (PNMS) system for the rapid assessment of water toxicity. This technique is based on the plasmonic sensing of the nanomechanical movement of single bacterial cells, which could be inhibited upon exposure to potential toxicants. By correlating the amplitude of nanomechanical movement with bacterial activity, we detected a variety of toxic substances in water. The direct readout of bacterial activity via PNMS allowed for a high sensitivity to toxicants in water, thereby enabling us to evaluate the acute toxicological effect of chemical compounds rapidly. The PNMS method is promising for online alerts of water quality safety and for assessing chemical hazards. We anticipate that PNMS is also suitable for a wide range of other applications, including bacterial detection and high-throughput screening of antibacterial materials.

Neo-tanshinlactone (1) and its previously reported analogues, such as 2, are potent and selective in vitro antibreast cancer agents. The synthetic pathway to 2 was optimized from seven to five steps, with a better overall yield. Structure-activity relationships studies on these compounds revealed some key molecular determinants for this family of antibreast agents. Several derivatives (19-21 and 24) exerted potent and selective antibreast cancer activity with IC(50) values of 0.3, 0.2, 0.1, and 0.1 microg/mL, respectively, against the ZR-75-1 cell lines. Compound 24 was 2- to 3-fold more potent than 1 against SK-BR-3 and ZR-75-1. Importantly, 21 exhibited high selectivity; it was 23 times more active against ZR-75-1 than MCF-7. Compound 20 had an approximately 12-fold ratio of SK-BR-3/MCF-7 selectivity. In addition, analogue 2 showed potent activity against a ZR-75-1 xenograft model, but not PC-3 and MDA-MB-231 xenografts, as well as high selectivity against breast cancer cell line compared with normal breast tissue-derived cell lines. Further development of lead compounds 19-21 and 24 as clinical trial candidates is warranted.

The finding of the enhanced polymerization of N,N-carbonyldiimidazole (CDI) activated l-α-glutamic acid (Glu) by alkali cations like Na+ and K+ and CDI-activated l-α-arginine (Arg) by halide anions like Cl- and other common ions indicates the importance of the weak electrostatic coordination of these common ions on the polymerization of charged amino acids in H2O. Here the copolymerization of l-arginine-N-carboxyanhydride (l-Arg-NCA) mixed with l-glutamic acid-N-carboxyanhydride (l-Glu-NCA) produced much longer peptides than that of the same concentration of l-Arg-NCA or l-Glu-NCA, and the optimal proportion of l-Glu-NCA over l-Arg-NCA for the longest peptide formation was 1:1. NaCl affected the sequences of the peptides formed in the mixed l-Arg-NCA with l-Glu-NCA, yielding peptides with significantly more Arg residues than Glu residues. Enzymatic hydrolysis of the formed peptides uncovered significantly more two residues of the same charges. These data strengthen the importance of weak electrostatic int...