Effect of Co2+-substitution on the substrate specificity of phospholipase C from Bacillus cereus during attack on two membrane systems

A rhodamine based chemosensor for solvent dependent chromogenic sensing of cobalt (II) and copper (II) ions with good selectivity and sensitivity: Synthesis, filter paper test strip, DFT calculations and cytotoxicity

A new chemosensor 1 was synthesized by reacting rhodamine B hydrazide and 2,3,4-trihydroxybenzaldehyde, which was then characterized by spectroscopic techniques and single crystal X-ray crystallography. Sensor 1 has the ability to sense Co²⁺/Cu²⁺ ions by "naked-eye" with an apparent colour change from colourless to pink in different solvent system, MeCN and DMF respectively. Furthermore, it can selectively detect Co²⁺/Cu²⁺ among wide range of different metal ions, and it exhibits low detection limit of 4.425 × 10^-8 M and 1.398 × 10^-7 M respectively. Binding mode of the two complexes were determined to be 1:1 stoichiometry for Co²⁺ complex and 1:2 stoichiometry for Cu²⁺ complex through Job's plot, IR spectroscopy, mass spectrometry and ¹H NMR spectroscopy. Moreover, reversibility of the sensor 1 as copper (II) ion detector was determined by using EDTA and the results showed that sensor 1 can be reused for at least 6 cycles. Other than that, a low cost chemosensor test strips were fabricated for the convenient "naked-eye" detection of Co²⁺ and Cu²⁺ in pure aqueous media. The MTT assay was conducted in order to determine the cytotoxicity of sensor 1 towards human cell lines.

Triple Action Sensing Behaviour of a Single Receptor for the Detection of Multiple Analytes via Different Approaches

The thiosemicarbazide based receptor was synthesized with 4-(diethylamino)salicylaldehyde and N- phenyl-thiosemicarbazide by the simple condensation method and the properties were studied under the naked eye, UV-Vis and fluorescence studies etc. The synthesized receptor detects cyanide, cobalt, and mercury in acetonitrile medium. The observed color changes included colourless to yellow for cyanide, colourless to green for cobalt and colourless to yellow for mercury which were seen under naked eye without the aid of any instruments. Furthermore, the cyanide bound receptor detects Cr³⁺ by the relay recognition method. The detection limit of receptor with cyanide, cobalt & mercury was found to be 5.8 × 10^- 7 M, 3.6 × 10^- 7 M and 8.1 × 10^- 7 M respectively. Experimental results were verified by DFT calculations. Receptor was successfully employed in the construction of INHIBIT and IMPLICATION logic gates.

Polyethylenimine-Assisted Generation of Optical Nanoprobes for Biosensing Applications

Detection of analytes in biological systems is pivotal to explore their physiological roles and provide diagnostic and treatment options for related diseases, which however remains a great challenge. Optical nanoprobes that exhibit absorption or fluorescence signal changes in response to the targets of interest have emerged as a versatile class of biosensors in the field. Polyethylenimine (PEI) with abundant amine groups plays indispensable roles in the construction of optical nanoprobes and mediating the sensing processes. After interaction with analytes, PEI-based optical nanoprobes can be induced to form aggregates, be disassembled or separated into individual units, or undergo structure/component alterations. As such, the optical properties of these nanoprobes have corresponding changes, allowing for sensitive and selective detection of a wide variety of analytes in biological environment. Up to now, detections of reactive oxygen species, pH, metal ions, biothiols, neurotransmitters, therapeutic agents, oxygen levels, enzyme activities, and virus/bacteria have been successfully demonstrated using PEI-based optical nanoprobes. Herein, we summarize the recent developments of PEI-based optical nanoprobes for biosensing applications and highlight the probe designs and sensing mechanisms. The existing challenges and prospects regarding biosensing applications of PEI-based optical nanoprobes are also briefly discussed.

A single colorimetric sensor for multiple targets: the sequential detection of Co2+and cyanide and the selective detection of Cu2+in aqueous solution

A colorimetric chemosensor was developed for simultaneous detection of Co²⁺and Cu²⁺and for sequential recognition of Co²⁺and CN⁻.

Selectively sensing first-row transition metal ions through fluorescence enhancement

Fluorescence signaling systems that give enhancement in the presence of first-row transition metal ions are discussed.

A highly selective colorimetric chemosensor for cobalt(ii) ions based on a tripodal amide ligand

A highly selective colorimetric chemosensor for cobalt(ii) ions was synthesized and structurally characterized by single crystal X-ray diffraction. The ligand enabled the detection of cobalt(ii) ions at a concentration of 10⁻⁵ mol L⁻¹ by the “naked-eye”.

Highly selective colorimetric chemosensor for Co2+

A new highly selective colorimetric chemosensor for Co(2+) was developed based on coumarin-conjugated thiocarbanohydrazone. The ligand senses Co(2+) in solution by changing its color from light yellow to deep pink. The sensor has been used in the development of practically viable colorimetric kits and as a staining agent for Co(2+) in microorganisms.