title: Water soluble and efficient amino acid Schiff base receptor for reversible fluorescence turn-on detection of Zn²⁺ ions: Quantum chemical calculations and detection of bacteria.
abstract: An amino acid Schiff base (R) capable of recognizing Zn(2+) ions selectively and sensitively in an aqueous medium was prepared and characterized. Upon addition of Zn(2+) ions, the receptor exhibits fluorescence intensity enhancements (~40 fold) at 460 nm (quantum yield, Φ=0.05 for R and Φ=0.18 for R-Zn(2+)) and can be detected by naked eye under UV light. The receptor can recognize the Zn(2+) (1.04×10(-8) M) selectively for other metal ions in the pH range of 7.5-11. The Zn(2+) chelation with R decreases the loss of energy through non-radiative transition and leads to fluorescence enhancement. The binding mode of the receptor with Zn(2+) was investigated by (1)H NMR titration and further validated by ESI-MS. The elemental color mapping and SEM/EDS analysis were also used to study the binding of R with Zn(2+). Density functional theory calculations were carried out to understand the binding mechanism. The receptor was applied as a microbial sensor for Escherichia coli and Staphylococcus aureus.
authors: Chemistry Research Centre, National Engineering College, K. R. Nagar, Kovilpatti 628503, Thoothukudi District, Tamil Nadu, India.
authors: L
authors: L
authors: Subha
authors: Chemistry Research Centre, National Engineering College, K. R. Nagar, Kovilpatti 628503, Thoothukudi District, Tamil Nadu, India.
authors: C
authors: C
authors: Balakrishnan
authors: Central Inter-Disciplinary Research Facility, Mahatma Gandhi Medical College & Research Institute Campus, Pillayarkuppam, Puducherry 607 402, India.
authors: Satheesh
authors: S
authors: Natarajan
authors: Chemistry Research Centre, National Engineering College, K. R. Nagar, Kovilpatti 628503, Thoothukudi District, Tamil Nadu, India.
authors: M
authors: M
authors: Theetharappan
authors: Central Inter-Disciplinary Research Facility, Mahatma Gandhi Medical College & Research Institute Campus, Pillayarkuppam, Puducherry 607 402, India.
authors: Balanehru
authors: B
authors: Subramanian
authors: Chemistry Research Centre, National Engineering College, K. R. Nagar, Kovilpatti 628503, Thoothukudi District, Tamil Nadu, India. Electronic address: drmaneelakantan@gmail.com.
authors: M A
authors: MA
authors: Neelakantan
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D001419:Bacteria / Q000166:cytology / Q000302:isolation & purification*; D003116:Color; D004926:Escherichia coli / Q000166:cytology / Q000302:isolation & purification; D005453:Fluorescence; D006863:Hydrogen-Ion Concentration; D007477:Ions; D007700:Kinetics; D057230:Limit of Detection; D008855:Microscopy, Electron, Scanning; D008958:Models, Molecular; D008968:Molecular Conformation; D066244:Proton Magnetic Resonance Spectroscopy; D011789:Quantum Theory; D012545:Schiff Bases / Q000737:chemistry*; D012995:Solubility; D013056:Spectrophotometry, Ultraviolet; D013211:Staphylococcus aureus / Q000166:cytology / Q000302:isolation & purification; D014867:Water / Q000737:chemistry*; D015032:Zinc / Q000032:analysis*
chemical_list: D000596:Amino Acids; D007477:Ions; D012545:Schiff Bases; D014867:Water; D015032:Zinc
keywords: Amino acid Schiff base receptor; Aqueous medium; Fluorescence; Microbial sensor; Zinc sensor