Chromone-Based Cd(II) Fluorescent Coordination Polymer Fabricated to Study Optoelectronic and Explosive Sensing Properties.

Here, electrical conductivity and explosive sensing properties of multifunctional chromone-Cd(II)-based coordination polymers (CPs) (1-4) have been explored. The presence of different pseudohalide linkers, thiocyanate ions, and dicyanamide ions resulted in 1D and 3D architecture in the CPs. Thin film devices developed from CPs 1-4 (complex-based Schottky devices, CSD1, CSD2, CSD3, and CSD4, respectively) showed semiconductor behavior. Their conductivity values increased under photo illumination (1.37 × 10-5, 1.85 × 10-5, 1.61 × 10-5, and 2.01 × 10-5 S m-1 under dark conditions and 5.06 × 10-5, 8.78 × 10-5, 7.26 × 10-5, and 10.21 × 10-5 S m-1 under light). The nature of the I-V plots of these thin film devices under light irradiation and dark are nonlinear rectifying, which has been observed in Schottky barrier diodes (SBDs). All four CPs (1-4) exhibited highly selective fluorescence quenching-based sensing properties toward well-known explosives, 2,4-dinitrophenol (DNP) and 2,4,6-trinitrophenol (TNP). The limit of detection (LOD) values are 55, 28, 27, and 31 µM for TNP and 78, 44, 32, and 41 µM for DNP for complexes 1-4, respectively. A structure property correlation has been established to explain optoelectronic and explosive sensing properties.

Exploring aryl hydrocarbon receptor (AhR) as a target for Bisphenol-A (BPA)-induced pancreatic islet toxicity and impaired glucose homeostasis: Protective efficacy of ethanol extract of Centella asiatica.

The estrogenic impact of Bisphenol-A (BPA), a widely recognized endocrine disruptor, causes disruption of pancreatic ß-cell function through estrogen receptors (ERs). While BPA's binding affinity for ERs is significantly lower than that of its natural counterpart, estrogen, recent observations of BPA's affinity for aryl hydrocarbon receptor (AhR) in specific cellular contexts have sparked a specific question: does AhR play a role in BPA's toxicological effects within the endocrine pancreas? To explore this question, we investigated BPA's (10 and 100 µg/ kg body weight/day for 21 days) potential to activate AhR within pancreatic islets and assessed the protective role of ethanol extract of Centella asiatica (CA) (200 and 400 mg/kg body weight/day for 21 days) against BPA-mediated toxicity in mouse model. Our results indicate that BPA effectively triggers the activation of AhR and modulates its target genes within pancreatic islets. In contrast, CA activates AhR but directs downstream pathways differentially and activates Nrf2. Additionally, CA was observed to counteract the disruption caused by BPA in glucose homeostasis and insulin sensitivity. Furthermore, BPA-induced oxidative stress and exaggerated production of proinflammatory cytokines were effectively counteracted by CA supplementation. In summary, our study suggests that CA influenced AhR signaling to mitigate the disrupted pancreatic endocrine function in BPA exposed mice. By shedding light on how BPA interacts with AhR, our research provides valuable insights into the mechanisms involved in the diabetogenic actions of BPA.

Aza-phenol Based Macrocyclic Probes Design for "CHEF-on" Multi Analytes Sensor: Crystal Structure Elucidation and Application in Biological Cell Imaging.

Metal bound macrocyclic compounds found in biological systems inspired us to design and synthesize two Robson-type macrocyclic Schiff-base chemosensors, H 2 L1 (H 2 L1=1,11-dimethyl-6,16-dithia-3,9,13,19-tetraaza-1,11(1,3)-dibenzenacycloicosaphane-2,9,12,19-tetraene-1,11-diol) and H 2 L2 (H 2 L2=1,11-dimethyl-6,16-dioxa-3,9,13,19-tetraaza-1,11(1,3)-dibenzenacycloicosaphane-2,9,12,19-tetraene-1,11-diol). Both the chemosensors have been characterized with different spectroscopic techniques. They act as multianalyte sensor and exhibit "turn-on" fluorescence toward different metal ions in 1X PBS (Phosphate Buffered Saline) solution. In presence of Zn2+, Al3+, Cr3+ and Fe3+ ions, H 2 L1 exhibits ∼6-fold enhancement of emission intensity, while H 2 L2 shows ∼6-fold enhancement of emission intensity in the presence of Zn2+, Al3+ and Cr3+ ions. The interaction between the different metal ion and chemosensor have been examined by absorption, emission, and 1H NMR spectroscopy as well as by ESI-MS+ analysis. We have successfully isolated and solved the crystal structure of the complex [Zn(H 2 L1)(NO3)]NO3 (1) by X-ray crystallography. The crystal structure of 1 shows 1:1 metal:ligand stoichiometry and helps to understand the observed PET-Off-CHEF-On sensing mechanism. LOD values of H 2 L1 and H 2 L2 toward metal ions are found to be ∼10-8 and ∼10-7 M, respectively. Large Stokes shifts of the probes against analytes (∼100 nm) make them a suitable candidate for biological cell imaging studies. Robson type phenol based macrocyclic fluorescence sensors are very scarce in the literature. Therefore, the tuning of structural parameters as the number and nature of donor atoms, their relative locations and presence of rigid aromatic groups can lead to the design of new chemosensors, which can accommodate different charged/neutral guest(s) inside its cavity. The study of the spectroscopic properties of this type of macrocyclic ligands and their complexes might open a new avenue of chemosensors.

Selective Low-Level Detection of a Perilous Nitroaromatic Compound Using Tailor-Made Cd(II)-Based Coordination Polymers: Study of Photophysical Properties and Effect of Functional Groups.

Three coordination polymers (CPs 1-3) are prepared based on diverse electron-donating properties and coordination arrangements of conjugated ligands. Interestingly, this is also reflected in their photophysical properties. The distinguishable high emissive nature of the luminescent coordination polymer shows its potentiality toward the detection of the perilous substance 2,4,6-trinitrophenol (TNP) or picric acid (PA). TNP has a higher propensity among explosive nitroaromatic compounds (epNACs) due to its significant π···π interaction with the free benzene moieties present in the CPs. Among CPs 1-3, 2 exhibits the highest sensitivity and selectivity toward TNP because of the most favorable π-π stacking with the conjugated organic linker. The calculated limit of detection (LOD) and corresponding quenching constant (KSV) from the Stern-Volmer (SV) plot for 1, 2, and 3 are found to be 0.68 µM and 7.49 × 104 M-1, 0.41 µM and 8.01 × 104 M-1, and 1.18 µM and 8.1 × 104 M-1, respectively. The fluorescence quenching mechanism is also highly influenced by their structure and coordination arrangement.

Two rhodamine-azo based fluorescent probes for recognition of trivalent metal ions: crystal structure elucidation and biological applications.

Two rhodamine and azo based chemosensors (HL1 = (3',6'-bis(ethylamino)-2-((2-hydroxy-3-methoxy-5-(phenyldiazenyl)benzylidene)amino)-2',7'-dimethylspiro[isoindoline-1,9'-xanthen]-3-one) and HL2 = (3',6'-bis(ethylamino)-2-(((2-hydroxy-3-methoxy-5-(p-tolyldiazenyl)benzylidene)amino)-2',7'-dimethylspiro[isoindoline-1,9'-xanthen]-3-one) have been synthesized for colorimetric and fluorometric detection of three trivalent metal ions, Al3+, Cr3+ and Fe3+. The chemosensors have been thoroughly characterized by different spectroscopic techniques and X-ray crystallography. They are non-fluorescent due to the presence of a spirolactam ring. The trivalent metal ions initiate an opening of the spirolactam ring when excited at 490 nm in Britton-Robinson buffer solution (H2O/MeOH 1 : 9 v/v; pH 7.4). The opening of the spirolactam ring increases conjugation within the probe, which is supported by an intense fluorescent pinkish-yellow colouration and an enhancement of the fluorescence intensity of the chemosensors by ∼400 times in the presence of Al3+ and Cr3+ ions and by ∼100 times in the presence of Fe3+ ions. Such a type of enormous fluorescence enhancement is rarely observed in other chemosensors for the detection of trivalent metal ions. A 2 : 1 binding stoichiometry of the probes with the respective ions has been confirmed by Job's plot analysis. Elucidation of the crystal structures of the Al3+ bound chemosensors (1 and 4) also justifies the 2 : 1 binding stoichiometry and the presence of an open spirolactam ring within the chemosensor framework. The limit of detection (LOD) values for both the chemosensors towards the respective metal ions are in the order of ∼10-9 M which supports their application in the biological field. The biocompatibility of the ligands has been studied with the help of the MTT assay. The results show that no significant toxicity was observed up to 100 µM of chemosensor concentration. The capability of our synthesized chemosensors to detect intracellular Al3+, Cr3+ and Fe3+ ions in the cervical cancer cell line HeLa was evaluated with the aid of fluorescence imaging.

Antibacterial potency of cytocompatible chitosan-decorated biogenic silver nanoparticles and molecular insights towards cell-particle interaction.

In the study, leaf extract of Carica papaya was utilized for the biogenic fabrication process of chitosan functionalized silver nanoparticles (Ag-Chito NPs). HRTEM analysis revealed that the fabricated Ag-Chito NPs was spherical in shape, with an average particle size of 13.31 (±0.07) nm. FTIR, UV-Vis, DLS, and other characterizations were also performed to analyze the diverse physicochemical properties of the particles. The antibacterial potency of the synthesized Ag-Chito NPs was tested against the two clinically isolated multidrug resistant uropathogenic bacterial strains, i.e. MLD 2 (Escherichia coli) and MLD 4 (Staphylococcus aureus) through MIC, MBC, time and concentration dependent killing kinetic assay, inhibition of biofilm formation assay, fluorescence and SEM imaging. Significantly, Ag-Chito NPs showed the highest sensitivity against the MLD 2 (MIC value of 12.5 µg/mL) strain, as compared to the MLD 4 (MIC value of 15 µg/mL) strain. From the hemolysis assay, it was revealed that Ag-Chito NPs exerted no significant toxicity up to 50 µg/mL against healthy human blood cells. Additionally, in silico analysis of chitosan (functionalized on the surface of AgNPs) and bacterial cell membrane protein also evidently suggested a strong interaction between Ag-Chito NPs and bacterial cells, which might be responsible for bacterial cell death.

Aza-Crown-Based Macrocyclic Probe Design for "PET-off" Multi-Cu2+ Responsive and "CHEF-on" Multi-Zn2+ Sensor: Application in Biological Cell Imaging and Theoretical Studies.

The work represents a rare example of an aza-crown-based macrocyclic chemosensor, H2DTC (H2DTC = 1,16-dihydroxy-tetraaza-30-crown-8) for the selective detection of both Zn2+ and Cu2+ in HEPES buffer medium (pH 7.4). H2DTC exhibits a fluorescence response for both Zn2+ and Cu2+ ions. The reversibility of the chemosensor in its binding with Zn2+ and Cu2+ ions is also examined using a Na2EDTA solution. H2DTC exhibits a chelation-enhanced fluorescence (CHEF) effect in the presence of Zn2+ ions and a quenching effect (CHEQ) in the presence of paramagnetic Cu2+ ions. Furthermore, the geometry and spectral properties of H2DTC and the chemosensor bound to Zn2+ have been studied by DFT and TDDFT calculations. The limit of detection (LOD) values are 0.11 × 10-9 and 0.27 × 10-9 M for Cu2+ and Zn2+, respectively. The formation constants for the Zn2+ and Cu2+ complexes have been measured by pH-potentiometry in 0.15 M NaCl in 70:30 (v:v) water:ethanol at 298.1 K. UV-vis absorption and fluorometric spectral data and pH-potentiometric titrations indicate 1:1 and 2:1 metal:chemosensor species. In the solid state H2DTC is able to accommodate up to four metal ions, as proved by the crystal structures of the complexes [Zn4(DTC)(OH)2(NO3)4] (1) and {[Cu4(DTC)(OCH3)2(NO3)4]·H2O}n (2). H2DTC can be used as a potential chemosensor for monitoring Zn2+ and Cu2+ ions in biological and environmental media with outstanding accuracy and precision. The propensity of H2DTC to detect intracellular Cu2+ and Zn2+ ions in the triple negative human breast cancer cell line MDA-MB-468 and in HeLa cells has been determined by fluorescence cell imaging.

Development of Rhodamine 6G-Based Fluorescent Chemosensors for Al3+-Ion Detection: Effect of Ring Strain and Substituent in Enhancing Its Sensing Performance.

Four rhodamine 6G-based chemosensors (H 3 L1-H 3 L4) are designed for selective detection of Al3+ ion. They are characterized using various spectroscopic techniques and X-ray crystallography. All absorption and emission spectral studies have been performed in 10 mM N-(2-hydroxyethyl)piperazine-N'-ethanesulfonic acid (HEPES) buffer solution at pH 7.4 in H2O/MeOH (9:1, v/v) at 25 °C. In absorption spectra, chemosensors exhibit an intense band around 530 nm in the presence of Al3+ ion. Chemosensors (H 3 L1-H 3 L4) are nonfluorescent when excited around 490 nm. The presence of Al3+ ion enhances the emission intensity (555 nm) many times. The formation of complexes 1-4 is established with the aid of different spectroscopic techniques. The limit of detection value obtained in the nanomolar range confirms the high sensitivity of the probes toward Al3+ ion. It has been observed that the presence of aliphatic spacers in the diamine part and different halogen substituents in the salicylaldehyde part strongly influences the selectivity of the chemosensors toward Al3+ ion. The propensity of the chemosensors to identify intracellular Al3+ ions in triple-negative human breast cancer cell line MDA-MB-468 by fluorescence imaging is also examined in this study.

Bioequivalence of two tacrolimus formulations under fasting conditions in healthy male subjects.

BACKGROUND: Tacrolimus is a macrolide immunosuppressant indicated for prophylaxis of transplant rejection. The European regulatory authorities require comparative bioavailability studies with an innovator product to grant marketing authorization of generic products. OBJECTIVE: The purpose of this study was to test the bioequivalence of generic (test) and innovator (reference) tacrolimus capsules. METHODS: Two open-label, 2-period, single-dose, crossover studies compared 0.5 mg and 5 mg capsule test formulations of tacrolimus with reference products in fasting, healthy male volunteers. The 2 study periods were separated by a 20-day (0.5 mg) or 21-day (5 mg) washout period. Blood samples were collected for up to 72 (0.5 mg) or 192 (5 mg) hours post-dose. Tacrolimus concentrations in whole blood were determined using a validated LC-MS/MS method. The primary evaluation criteria were C(max) and AUC(0-72) (0.5 mg) or AUC(0-t) (5 mg). Bioequivalence was assumed if the 90% CIs for the test/reference ratios of log-transformed C(max) and AUC values were within the limits specified by existing European guidelines. Data on safety and patient well-being were collected throughout the study. RESULTS: The 90% CIs for 0.5 mg were 102.99%-120.80% for C(max) and 91.51%-105.92% for AUC(0-72); those for 5 mg were 110.61%-120.96% for C(max) and 96.17%-103.55% for AUC(0-t). These values meet the requirements for assuming bioequivalence as defined in the European Medicines Agency guidelines for narrow therapeutic index drugs (80%-125% for C(max) and 90%-111% for AUC). There were no relevant differences in the safety profiles of the test and reference formulations. CONCLUSIONS: In these comparative bioavailability studies of fasting, healthy male volunteers, the test and reference formulations of tacrolimus 0.5 mg and 5 mg capsules were well tolerated and met the requirements of the European regulatory bioequivalence guidelines. Both studies have been submitted for registration with Clinical Trials Registry-India: CTRI application references REF/2011/05/002346 (0.5 mg) and REF/2011/05/002347 (5 mg).

Single-dose, two-way crossover, bioequivalence study of Mycophenolate mofetil 500 mg tablet under fasting conditions in healthy male subjects.

BACKGROUND: Mycophenolate mofetil (MMF) is an immunosuppressant indicated for prophylaxis of acute organ transplant rejection. Generic MMF is less costly than the branded product, but European regulatory authorities require bioequivalence studies for the marketing of generics. OBJECTIVES: The aims of the 2 studies reported were to assess the dissolution and bioavailability of a generic (test) and branded (reference) formulation of MMF 500 mg. METHODS: An in vitro analytical dissolution profile test was conducted comparing 500 mg MMF test drug with a reference drug. A separate single-dose, randomized, open-label, 2-way crossover study involving fasting, healthy, adult male volunteers was conducted. Two study periods-1 test drug period and 1 reference drug period-were separated by a 14-day washout period. Blood samples were collected for up to 60 hours after drug administration for the determination of MMF and mycophenolic acid (MPA) pharmacokinetics. Concentrations of the analytes were determined using a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method; pharmacokinetic parameters were calculated using noncompartmental analysis; C(max), AUC(0-t), and AUC(0-∞) were the primary evaluation criteria. Bioequivalence was assumed if the 90% confidence intervals (CIs) for the test/reference ratios of natural logarithm transformed values (obtained using ANOVA) were between 80% and 125%, per European regulations for bioequivalence. Tolerability was monitored throughout the study. RESULTS: The dissolution profiles of the test drug matched those of the reference drug at 4 pH levels. In the bioequivalence study, a total of 126 male subjects were dosed, and 117 subjects completed the study. The 90% CIs for MPA were C(max), 94.13% to 116.46%; AUC(0-t), 98.26% to 102.36%; and AUC(0-∞), 97.85% to 101.99%. These values met with the European regulatory definition of bioequivalence. Reported adverse events were similar in both the test and reference drugs. CONCLUSIONS: This single-dose study found that the test and reference MMF 500 mg tablets met the European regulatory criteria for assuming bioequivalence in fasting, healthy, male subjects. Both formulations were well tolerated. (Clinical Trials Registry - India [CTRI]: 2011/03/002211).

Nanosomal Amphotericin B is an efficacious alternative to Ambisome for fungal therapy.

Amphotericin B was formulated in lipids (Nanosomal Amphotericin B) without using any detergent or toxic organic solvents during the preparation. Electron microscopy and particle size determination of Nanosomal Amphotericin B showed a homogeneous population of nanosized particles below 100 nm. Hemolysis assay indicated that Nanosomal Amphotericin B causes significantly less lysis of red blood cells than Amphotericin B deoxycholate and was comparable to Ambisome. A maximum daily dose of Nanosomal Amphotericin B at 5 mg/kg in rabbits and 10 mg/kg in mice for 28 days showed no symptoms of toxicity, mortality or significant body weight reduction. Hematological and gross pathological analysis of tissues revealed no abnormalities attributable to the drug treatment. Nanosomal Amphotericin B and Ambisome were injected (iv) at 2 mg/kg consecutively for 5 days into mice infected with Aspergillus fumigatus. The treatment resulted in 90% survival with Nanosomal Amphotericin B and only 30% survival with Ambisome after 10 days of fungal infection. However, all of the 10 control mice which were not treated with Amphotericin B died within 5 days of fungal infection. Nanosomal Amphotericin B is safe, cost effective and provides an alternative option for treatment of fungal disease.