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1. Chiroptical sensing of homocysteine

   https://doi.org/10.1039/D0OB01798A  

   Thanzeel, F. Yushra; Zandi, Lily S.; Wolf, Christian (November 2020, Organic & Biomolecular Chemistry)

   null (Ed.)

   The cyclization reaction between ortho -phthalaldehyde and l -homocysteine coincides with the generation of a pronounced positive CD signal at approximately 335 nm. Under identical conditions, other amino acids including cysteine produce very weak CD responses. This unusual substrate specificity allows accurate chiroptical analysis of the enantiomeric composition of homocysteine samples in the presence of cysteine without the need for time-consuming chromatographic separation. This significantly simplifies and speeds up ee determination at reduced solvent waste production. 

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2. Quantitative Chiroptical Sensing of Free Amino Acids, Biothiols, Amines, and Amino Alcohols with an Aryl Fluoride Probe

   https://doi.org/10.1021/jacs.9b07588  

   Thanzeel, F. Yushra; Sripada, Archita; Wolf, Christian (September 2019, Journal of the American Chemical Society)
3. Chiroptical Sensing of Amines With Isatins

   https://doi.org/10.1002/chir.70002  

   Kariapper, F Safia; Miccolis, Flavia; Pilicer, Samantha L; Wolf, Christian (November 2024, Chirality)

   Isatins are extensively researched compounds with diverse applications, particularly as synthetic precursors in pharmaceutical developments. However, their use as optical probes for enantioselective sensing of chiral amines has not been explored to date. Herein, we present a novel chiroptical assay with an optimized isatin that generates strong, red‐shifted circular dichroism (CD) signals at approximately 380 nm upon ketimine formation with chiral amines. The intensity of the induced CD signal increases linearly with the enantiomeric excess of the analyte and thus allows quantitative chirality analysis. The general usefulness of this approach is demonstrated with a broad range of aliphatic and aromatic chiral amines, and by accurate determination of the enantiomeric composition of 10 samples. 

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4. Molecular Insights into the Influence of Ions on the Water Structure. I. Alkali Metal Ions in Solution

   https://doi.org/10.1021/acs.jpcb.3c08150  

   Savoj, Roya; Agnew, Henry; Zhou, Ruihan; Paesani, Francesco (February 2024, The Journal of Physical Chemistry B)
5. Probe-assisted detection of Fe3+ ions in a multi-functionalized nanopore

   https://doi.org/10.1016/j.bios.2024.116125  

   Arora, Pearl; Zheng, Haiyan; Munusamy, Sathishkumar; Jahani, Rana; Wang, Liang; Guan, Xiyun (May 2024, Biosensors and Bioelectronics)

   Iron is an essential element that plays critical roles in many biological/metabolic processes, ranging from oxygen transport, mitochondrial respiration, to host defense and cell signaling. Maintaining an appropriate iron level in the body is vital to the human health. Iron deficiency or overload can cause life-threatening conditions. Thus, developing a new, rapid, cost-effective, and easy to use method for iron detection is significant not only for environmental monitoring but also for disease prevention. In this study, we report an innovative Fe3+ detection strategy by using both a ligand probe and an engineered nanopore with two binding sites. In our design, one binding site of the nanopore has a strong interaction with the ligand probe, while the other is more selective toward interfering species. Based on the difference in the number of ligand DTPMPA events in the absence and presence of ferric ions, micromolar concentrations of Fe3+ could be detected within minutes. Our method is selective: micromolar concentrations of Mg2+, Ca2+, Cd2+, Zn2+, Ni2+, Co2+, Mn2+, and Cu2+ would not interfere with the detection of ferric ions. Furthermore, Cu2+, Ni2+, Co2+, Zn2+, and Mn2+ produced current blockage events with quite different signatures from each other, enabling their simultaneous detection. In addition, simulated water and serum samples were successfully analyzed. The nanopore sensing strategy developed in this work should find useful application in the development of stochastic sensors for other substances, especially in situations where multi-analyte concurrent detection is desired. 

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