Construction of coumarin-appended calix[4]arene-based fluorescence sensor for the detection of carbofuran in cabbage.

This study presents a novel approach for the detection of carbofuran (CBF) insecticide by systematically exploring a calix[4]arene-derived fluorescence probe, CouC4S, functionalized with two coumarin-labelled cystamine linkages at the narrow edge of the calix[4]arene platform. The proposed method showed a fluorescence "signal - off" effect when CBF binds with CouC4S by quenching the fluorescence intensity of CouC4S. Its limit of detection was as low as 5.55 µM according to the emission study. The working concentration range for this ligand was observed to be up to 5-65 µM. This method could be applied for the on-spot detection of CBF in real samples such as cabbage by spiking CBFvia in situ experiments, which exhibited a limit of detection of 8.823 ppm. For the further confirmation of CouC4S:CBF binding, cyclic voltammetry, differential pulse voltammetry, powder X-ray diffraction, FT-IR spectroscopy, 1H NMR titration, MALDI-TOF and computational investigations were carried out.

Meglumine-based Sustainable Three-component Deep Eutectic Solvent Applicable for the Synthesis of Pyrazolo[5,1-b]quinazoline-3-carboxylates as a Sensing Probe for Cu2+ Ions.

An unprecedented meglumine-based three-component deep eutectic solvent (3c-DES) (MegPAc) was synthesized using meglumine, p-toluenesulfonic acid (PTSA), and acetic acid as a renewable, and non-toxic solvent. The exploitation of the MegPAc as an eco-friendly reaction media to construct a selective and sensitive small organic molecular sensing probe, namely, pyrazolo[5,1-b]quinazoline-3-carboxylates (PQCs) was executed. Captivatingly, the MegPAc served the dual role of solvent and catalyst, and it delivered the title components with 69-94 % yields within 67-150 minutes. Furthermore, a UV-visible study unfolds the selective detection of Cu2+ ions with our synthetic probe 4 ba and resulted in hypsochromic shift due to electrostatic interactions. Additionally, 1H NMR titration study and density functional theory (DFT) calculations were performed to attest the binding mechanism of sensing probe 4 ba and Cu2+ ions. Worthy of mention, this protocol unveils the efficacy of meglumine-based 3c-DES for the first time as a bio-renewable system to synthesize the PQCs.

Turn on fluorescence strip based sensor for recognition of Sr2+ and CN- via lowerrim substituted calix[4]arene and its computational investigation.

Fluorescence sensor L designed around a calix[4]arene scaffold, bearing two fluorogenic aminoquinoline moities, has been synthesized. It is found to be selective and sensitive towards Sr2+ and CN- over a wide range of cations and anions in a spectrofluorometric study in acetonitrile. The ion-binding property of L was monitored by fluorescence spectroscopy, UV-vis spectroscopy, ESI-MS, 1H NMR, FT-IR investigation and PXRD study. The host L shows a minimum detection limit which is 1.36 nM for Sr2+ and 1.23 nM for CN- having concentration range 5-120 nM and 5-115 nM respectively. The calculated binding constants for L:Sr2+ and L: CN- are respectively 8.859 × 108 M-1 and 8.574 × 108 M-1. Our host L has been utilised in formation of a user-friendly, affordable, and disposable paper-based analytical device (PAD) for rapid chemical screening of Sr2+ and CN- ion via single strip. Moreover, the optimization of probe L has also been done by the MOPAC-2016 software package using NM7 popular method resulting -21.71 kcals/mol heat of formation and also determined the HOMO-LUMO energy band gap for L, L:Sr2+ and L: CN-. Further, molecular docking score has been calculated using HEX software. The applicability of our probe in real samples containing Sr2+ and CN- has also been checked by emission study with 94-99% recovery.

A simple and rapid creatinine sensing via DLS selectivity, using calix[4]arene thiol functionalized gold nanoparticles.

A new, simple, ultra-sensitive and selective approach has been reported for the "on spot" colorimetric detection of creatinine based on calix[4]arene functionalized gold nanoparticles (AuNPs) with excellent discrimination in the presence of other biomolecules. The lower detection limit of the method is 2.16nM. The gold nanoparticles and p-tert-butylcalix[4]arene were synthesized by microwave assisted method. Specifically, in our study, we used dynamic light scattering (DLS) which is a powerful method for the determination of small changes in particle size, improved selectivity and sensitivity of the creatinine detection system over colorimetric method. The nanoassembly is characterized by Transmission electron microscopy (TEM), DLS, UV-vis and ESI-MS spectroscopy, which demonstrates the binding affinity due its ability of hydrogen bonding and electrostatic interaction between -NH group of creatinine and pSDSC4. It exhibits fast response time (<60s) to creatinine and has long shelf-life (>5 weeks). The developed pSDSC4-AuNPs based creatinine biosensor will be established as simple, reliable and accurate tool for the determination of creatinine in human urine samples.

A unique fluorescence biosensor for selective detection of tryptophan and histidine.

A novel photoinduced electron transfer (PET) based substituted calix[4]arene fluoroionophore has been used for the selective recognition of tryptophan (L-Trp) and histidine (L-His) by emission spectroscopy. The detection limit of the synthesized receptor was found to be 0.00826 nM for L-Trp and 0.00158 nM for L-His. Moreover, this probe has been applied for the recognition of L-Trp and L-His from blood serum.

Melamine modified gold nanoprobe for "on-spot" colorimetric recognition of clonazepam from biological specimens.

Inexpensive, rapid, and reliable methods of detection are crucial to the control of toxicological investigations. Here we report a highly sensitive, selective and cost effective method for the detection of trace amounts of clonazepam based on gold nanoparticles (AuNPs) in the presence of melamine. Hydrogen bonding interactions between clonazepam and melamine resulted in the aggregation of AuNPs and a consequent color change of AuNPs from wine red to blue. The results showed that the absorption ratio (A636/A552) was linear for clonazepam concentrations in the range of 10 × 10(-8) to 1.0 × 10(-9) M (R(2) = 0.999). The detection limit was 8.9 × 10(-10) M (S/N = 3), which was much lower than that of most existing methods. Coexisting substances including alprazolam, diazepam, nitrazepam and lorazepam did not affect the determination of clonazepam. The sensor developed by this new approach could be used as a spot test and a good alternative means for on-site and real time screening of clonazepam. This proposed scheme was also supported by the use of real samples such as skeletal remains and blood to illustrate the applicability of the developed nanosensor by a series of experiments.

A highly efficient PET switch on-off-on fluorescence receptor based on calix[4]arene for the selective recognition of Cd2+ and Sr2+.

A novel PET (photoinduced electron transfer) based substituted calix[4]arene fluoroionophore has been synthesized and used for the selective recognition of Cd(2+) and Sr(2+) by emission spectra. The detection limit of the synthesized receptor was found to be 0.94 pM for Cd(2+) and 1.04 pM for Sr(2+). Moreover, this probe has been applied to the recognition of Cd(2+) and Sr(2+) in waste water.

Fluorescence switch on-off-on receptor constructed of quinoline allied calix[4]arene for selective recognition of Cu2+ from blood serum and F- from industrial waste water.

A novel PET with ICT based substituted calix[4]arene fluroionophore was synthesized and used for detection of Cu(2+) and F(-) by emission spectra. The detection limit of the synthesized receptor was found to be 4.16 nM for Cu(2+) and 2.15 nM for F(-). Moreover, this probe has been applied for recognition of Cu(2+) in blood serum and F(-) from waste water.

A non enzymatic glucose biosensor based on an ultrasensitive calix[4]arene functionalized boronic acid gold nanoprobe for sensing in human blood serum.

We developed a new, advanced, simple and non enzymatic approach for the colorimetric detection of glucose based on calix[4]arene/phenyl boronic acid (CX-PBA)functionalized gold nanoparticles (AuNPs). This molecular receptor proficiently and selectively recognizes glucose due to its ability to reversibly bind diol-containing compounds. The assembly was characterized by transmission electron micrograph (TEM), dynamic light scattering (DLS), UV-Vis, FT-IR, ESI-MS and (1)H NMR spectrometry, which demonstrates the binding affinity for glucose via a boronic acid-diol interaction. The linear range for glucose was found to be 5-100 nM with phosphate buffer pH 10, with a lower detection limit of 4.3 nM. Interference by other saccharides was negligible. The biosensor has been successfully applied to estimate the glucose in human blood serum samples and the results compared well to an automatic analyzer. With the advantages of high sensitivity, selectivity and low sample volume, this method is potentially suitable for the on-site monitoring of glucose.

A novel calix[4]arene thiol functionalized silver nanoprobe for selective recognition of ferric ion with nanomolar sensitivity via DLS selectivity in human biological fluid.

A high concern for human health and safety has motivated dynamic research on the potential impact of transition metal ions and their toxic effects, thus it is very challenging to design transition-metal ion detection devices that are cost-effective, rapid and applicable to the biological milieus. Driven by the need to detect trace amounts of Fe(3+) from blood samples, we report a highly selective and ultrasensitive calix[4]arene modified silver nanoprobe for Fe(3+) recognition at the 9.4 nM level from aqueous solution with excellent discrimination against other heavy metals and biomolecules. The assembly was characterized by TEM (transmission electron microscopy), DLS (dynamic light scattering), UV-Vis, FT-IR, ESI-MS and (1)H NMR spectrometry, which demonstrate the higher binding affinity for Fe(3+). The biosensor has been successfully applied to estimate the ferric ion in human blood serum as well as in human hemoglobin.

An ICT based "turn on/off" quinoline armed calix[4]arene fluoroionophore: its sensing efficiency towards fluoride from waste water and Zn2+ from blood serum.

A novel structurally simple calix[4]arene appended 8-amidoquinoline linked conjugate was synthesized and has been used as a turn-on fluorescence probe for Zn(2+) and turn off fluorescence probe for F(-). Moreover, this probe has been applied for Zn(2+) detection in blood serum upto 8.7 µM and fluoride detection upto 22 nM in waste water samples, using emission spectra.

Calixarene capped ZnS quantum dots as an optical nanoprobe for detection and determination of menadione.

In this communication we report a p-sulfonatocalix[4]arene coated ZnS quantum dots "cup type" highly stable optical probe for the detection and determination of menadione (VK(3)) with high sensitivity and selectivity. The detection of VK(3) depends on supramolecular host-guest chemistry.

Analytical detection and method development of anticancer drug Gemcitabine HCl using gold nanoparticles.

A simple, rapid, cost effective and extractive UV spectrophotometric method was developed for the determination of Gemcitabine HCl (GMCT) in bulk drug and pharmaceutical formulation. It was based on UV spectrophotometric measurements in which the drug reacts with gold nanoparticles (AuNP) and changes the original colour of AuNP and forms a dark blue coloured solution which exhibits absorption maximum at 688nm. The apparent molar absorptivity and Sandell's sensitivity coefficient were found to be 3.95×10(-5)lmol(-1)cm(-1) and 0.060µgcm(-2) respectively. Beer's law was obeyed in the concentration range of 2.0-40µgml(-1). This method was tested and validated for various parameters according to ICH guidelines. The proposed method was successfully applied for the determination of GMCT in pharmaceutical formulation (parental formulation). The results demonstrated that the procedure is accurate, precise and reproducible (relative standard deviation <2%). As it is simple, cheap and less time consuming, it can be suitably applied for the estimation of GMCT in dosage forms.