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1. Fluorescent molecular rotors as versatile in situ sensors for protein quantitation

   https://doi.org/10.1038/s41598-023-46571-5  

   Daus, Kevin; Tharamak, Sorachat; Pluempanupat, Wanchai; Galie, Peter A; Theodoraki, Maria A; Theodorakis, Emmanuel A; Alpaugh, Mary L (December 2023, Scientific Reports)

   Abstract Accurate protein quantitation is essential for many cellular mechanistic studies. Existing technology relies on extrinsic sample evaluation that requires significant volumes of sample as well as addition of assay-specific reagents and importantly, is a terminal analysis. This study exploits the unique chemical features of a fluorescent molecular rotor that fluctuates between twisted-to-untwisted states, with a subsequent intensity increase in fluorescence depending on environmental conditions (e.g., viscosity). Here we report the development of a rapid, sensitive in situ protein quantitation method usingARCAM-1, a representative fluorescent molecular rotor that can be employed in both non-terminal and terminal assays. 

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2. DNA Analysis by Native Polyacrylamide Gel Electrophoresis and Infrared Fluorescence Imaging V.2

   https://doi.org/10.17504/protocols.io.mcyc2xw  

   Van Dyke, Michael; Cox, James (December 2018, Protocols.io)

   Short DNA probes, for example, those used in characterizing protein-DNA complexes, have historically been radiolabeled with 32P to allow their detection and quantitation following native polyacrylamide gel electrophoresis (PAGE). For reasons of economy or safety, alternative means of DNA detection need to be used. Described here is the resolution of 5' IRD700 and IRD800 end-labeled DNAs by native PAGE and their visualization and quantitation by IR fluorescence imaging. 

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3. Pillar[ n ]MaxQ: A New High Affinity Host Family for Sequestration in Water

   https://doi.org/10.1002/anie.202005902  

   Xue, Weijian; Zavalij, Peter Y.; Isaacs, Lyle (June 2020, Angewandte Chemie International Edition)

   Abstract We report the synthesis, X‐ray crystal structure, and molecular recognition properties of pillar[n]arene derivativeP[6]AS, which we refer to as Pillar[6]MaxQ along with analoguesP[5]ASandP[7]AStoward guests1–18. The ultratight binding affinity ofP[5]ASandP[6]AStoward quaternary (di)ammonium ions renders them prime candidates for in vitro and in vivo non‐covalent bioconjugation, for imaging and delivery applications, and as in vivo sequestration agents. 

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4. Distinctive biotransformation and biodefluorination of 6:2 versus 5:3 fluorotelomer carboxylic acids by municipal activated sludge

   https://doi.org/10.1016/j.watres.2024.121431  

   Wu, Chen; Goodrow, Sandra; Chen, Hao; Li, Mengyan (May 2024, Water Research)

   Fluorotelomer carboxylic acids (FTCAs) represent an important group of per- and polyfluoroalkyl substances (PFAS) given their high toxicity, bioaccumulation potential, and frequent detection in landfill leachates and PFAS-impacted sites. In this study, we assessed the biodegradability of 6:2 FTCA and 5:3 FTCA by activated sludges from four municipal wastewater treatment plants (WWTPs) in the New York Metropolitan area. Coupling with 6:2 FTCA removal, significant fluoride release (0.56∼1.83 F-/molecule) was evident in sludge treatments during 7 days of incubation. Less-fluorinated transformation products (TPs) were formed, including 6:2 fluorotelomer unsaturated carboxylic acid (6:2 FTUCA), perfluorohexanoic acid (PFHxA), perfluoropentanoic acid (PFPeA), and perfluorobutanoic acid (PFBA). In contrast, little fluoride (0.01∼0.09 F-/molecule) was detected in 5:3 FTCA-dosed microcosms, though 25∼68% of initially dosed 5:3 FTCA was biologically removed. This implies the dominance of “non-fluoride-releasing pathways” that may contribute to the formation of CoA adducts or other conjugates over 5:3 FTCA biotransformation. The discovery of defluorinated 5:3 FTUCA revealed the possibility of microbial attacks of the C-F bond at the γ carbon to initiate the transformation. Microbial community analysis revealed the possible involvement of 9 genera, such as Hyphomicrobium and Dechloromonas, in aerobic FTCA biotransformation. This study unraveled that biotransformation pathways of 6:2 and 5:3 FTCAs can be divergent, resulting in biodefluorination at distinctive degrees. Further research is underscored to uncover the nontarget TPs and investigate the involved biotransformation and biodefluorination mechanisms and molecular basis. 

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5. Infrared spectroscopy of ions and ionic clusters upon ionization of ethane in helium droplets

   https://doi.org/10.1063/5.0091819  

   Erukala, Swetha; Feinberg, Alexandra J.; Moon, Cheol Joo; Choi, Myong Yong; Vilesov, Andrey F. (May 2022, The Journal of Chemical Physics)

   Helium droplets are unique hosts for isolating diverse molecular ions for infrared spectroscopic experiments. Recently, it was found that electron impact ionization of ethylene clusters embedded in helium droplets produces diverse carbocations containing three and four carbon atoms, indicating effective ion–molecule reactions. In this work, similar experiments are reported but with the saturated hydrocarbon precursor of ethane. In distinction to ethylene, no characteristic bands of larger covalently bound carbocations were found, indicating inefficient ion–molecule reactions. Instead, the ionization in helium droplets leads to formation of weaker bound dimers, such as (C₂H₆)(C₂H₄)⁺, (C₂H₆)(C₂H₅)⁺, and (C₂H₆)(C₂H₆)⁺, as well as larger clusters containing several ethane molecules attached to C₂H₄⁺, C₂H₅⁺, and C₂H₆⁺ionic cores. The spectra of larger clusters resemble those for neutral, neat ethane clusters. This work shows the utility of the helium droplets to study small ionic clusters at ultra-low temperatures. 

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