Search

Two new coordination polymers (CPs), namely [Cd2(L)(2,2′-bipy)] (1) and [Cd2(L)(H2O)4] (2) (H4L = [1,1′-biphenyl]-2,3,3′,5′-tetracarboxylic acid and 2,2′-bipy = 2,2′-bipyridine), have been successfully synthesized under solvothermal conditions. 1 exhibits a 2D layer that was further extended into a 3D supramolecular framework through the packing interaction. 2 has a 3D 3,3,4-c network with a point symbol of (62·82)(63)2. The sensing results illustrated that both of them could be prospective candidates for developing luminescent sensors for the probing of Fe3+ and CrO42−. The probe effects remained highly selective to the Fe3+ and CrO42− ions even if there are other interfering ions. The limits of detection (LODs) for Fe3+/CrO42− were calculated to be ca. 2.47 × 10−8 M−1/1.12 × 10−8 M−1 and 1.35 × 10−9 M−1/2.23 × 10−8 M−1 for 1 and 2, respectively. The fluorescence resonance energy transfer process may be the major pathway behind the quenching mechanism for Fe3+ and CrO42- ions. The recycling operation indicated that compounds 1 and 2 are promising reusable probes for their effective capability of detecting Fe3+ and CrO42− ions.

With increasing pathogenic bacterial infection that is occurring worldwide, antibacterial therapy has become an important research field. There is great antimicrobial potential in the nanomaterial-based metal–organic framework (MOF) platform because it is highly biocompatible, biodegradable, and nontoxic, and it is now widely used in the anticancer agent industry and in the production of medical products. This review summarizes the possible mechanisms of representative MOF-based nanomaterials, and recounts recent progress in the design and development of MOF-based antibacterial materials for the remedy of postoperative infection. The existing shortcomings and future perspectives of the rapidly growing field of antimicrobial therapy addressing patient quality of life issues are also briefly discussed. Because of their wide applicability, further studies on the use of different MOF antimicrobial therapies will be of great interest.

Coordination polymers (CPs) are peculiar class of multidimensional materials which can be employed as photocatalytic materials to decompose lethal aromatic dyes present in waste-water discharge. Herein, four new Zn(II)/Cd(II) coordination polymers (CPs) namely [Cd2(H2O)(H3L)2(2,2′-bipy)2]·H2O (1), [Zn2(HL)(H2O)2(2,2′-bipy)2]·H2O (2), [Cd2(HL)(bmb)0.5(H2O)]·2H2O (3) and [Zn4(L)2(bpz)4·H2bpz]·4H2O (4) (H5L = 3,5-bis(3,4-dicarboxylphenoxy)benzoic acid, 2,2′-bipy = 2,2′-bipyridine, bmb = 1,4-bis(2-methylimidazol-1-yl)butane, bpz = 3,3′,5,5′-tetramethyl-4,4′-bipyrazole), have been synthesized solvothermally and characterized. The single crystal X-ray diffraction reveals that CPs 1 and 2 exhibit 2D supramolecular framework built by the hydrogen bond interactions between adjacent chains. The CP 3 features a 2D double layer while 4 display 3D 3,3,4,4-connected topology with point symbol {4.6.84}{4.6.8}{62.84}{62.8}. All these newly synthesized materials exhibit photocatalytic properties and the results demonstrated that they exhibit efficient photocatalytic performances to selectively degrade methylene blue (MB) among the dyes viz. methylene orange (MO), acid orange (AO), congo red (CR) and acid chrome blue (ACB) under UV irradiation. A mechanistic investigation toward better understanding of the photocatalytic degradation of MB has been carried out using LC-MS studies. Also computational investigation by performing band gap calculations have been accomplished to address the probable mechanistic pathway which further have been assisted with Hirshfeld surface analysis.

Two 2D Cd(II)/Co(II)-based polymers derived from 1-(3,4-dicarboxylphenyl)-4-(5-carboxy-1H-benzimidazol-2-yl) benzene (H3L), namely, [Cd3(H2O)(L)2(phen)2·7H2O] (1) and [Co3(H2O)2(L)2(2,2′-bipy)2·3H2O] (2), have been obtained and characterized. Compound 1 shows a 3D supramolecular network through π···π interactions from the inter-layer phenanthrolines. While 2 has 1D chain construct by the integration of metal center and side substitution of the flexible tricarboxylate linker. Apart from this, the photocatalytic activity of the Cd-based CP 1 was also evaluated under UV light irradiation which revealed efficient photocatalytic activity (52.3%) for methylene blue (MB) degradation without the use of any enhancers. The major intermediate degradation products were authenticated by LC-MS methodology to speculate on their possible degradation mechanisms of MB.

Two new Zn(II) metal-organic-frameworks displaying supramolecular isomerism have been synthesized using 1,3-bis(2-methylimidazolyl)propane (bmp) and 1,3,5-benzenetricarboxylic acid (H3BTC). The isomer [NH2(CH3)2][Zn2O(bmp)(BTC)] (1) adopt 2-fold interpenetrating framework topology defined by bey-type of interpenetration while another isomer [NH2(CH3)2][Zn2O(bmp)(BTC)].1.5DMF (2) adopt 2-fold interpenetrating framework topology defined by CdSO4-type of interpenetration. The difference in topologies of two MOFs can be ascribed to the flexibility of 1,3-bis(2-methylimidazolyl)propane ligand; because of which 2 lies on a crystallographic mirror plane. Both MOFs display efficient photocatalytic properties for the photodegradation of model aromatic dye methyl violet (MV). The photocatalytic mechanism in both the MOFs have been explained by using density of states calculations. Moreover, chromatography-mass spectrometry (LC-MS) has been performed to further validate the potential photodegradation mechanism of MV.

Two new Cu(II)/Co(II) coordination polymer (CPs) namely, [Co2(H2O)2(L)2(2,2′-bipy)2·H2O] (1) and [Cu2(L)2(bbi)] (2) (H2L=3,3′-(1,2-phenylenebis(methyleneoxy)) dibenzoic acid, bbi = 1,1′-(1,4-butanediyl)bis(imidazole), 2,2,’-bipy=2,2,’-bipyridine), have been designed and synthesized. 1 has 1D helical structure built by the connectivity of Co atoms and phenolic-oxygen containing branches of the flexible dicarboxylate linkages, which was further form a 2D supramolecular sheet through the strong π···π stacking interactions and H-bonded interactions. 2 exhibits 2D layer constructed by the double [Cu4L2] chains and anti-conformational bbi ligands. The current results illustrated that the N-donor ligand may play a distinct effect in the formation of these mortifies. The photocatalytic performances to degrade methyl violet (MV) and Rhodamine B (Rh B) under UV irradiation were studied.

During embryonic development, differentiation of cochlear progenitor cells into hair cells (HCs) or supporting cells (SCs) is partially controlled through Notch signaling. Many studies have shown that inhibition of Notch signaling allows SCs to convert into HCs in both normal and drug damaged neonatal mouse cochleae. This mechanism is also implicated during HC regeneration in non-mammalian vertebrates; however, the mechanism of spontaneous HC regeneration in the neonatal mouse cochlea is less understood. While inhibition of Notch signaling can force SCs to convert into HCs and increase the number of regenerated HCs, it is currently unknown whether this pathway is involved in spontaneous HC regeneration observed in vivo. Therefore, we investigated the role of Notch signaling during the spontaneous HC regeneration process using Atoh1-CreERTM::Rosa26loxP-stop-loxP-DTA/+ mice injected with tamoxifen at postnatal day (P) 0 and P1 to ablate HCs and stimulate spontaneous HC regeneration. Expression changes of genes in the Notch pathway were measured using immunostaining and in situ hybridization, with most changes observed in the apical one-third of the cochlea where the majority of HC regeneration occurs. Expression of the Notch target genes Hes1, Hes5, Hey1, HeyL, and Jagged1 were decreased. To investigate whether reduction of Notch signaling is involved in the spontaneous HC regeneration process, we overexpressed the Notch1 intracellular fragment (N1ICD) in cochlear SCs and other non-sensory epithelial cells in the context of HC damage. Specifically, Atoh1-CreERTM::Rosa26loxP-stop-loxP-DTA/+::Sox10rtTA::TetO-LacZ::TetO-N1ICD mice were injected with tamoxifen at P0/P1 to stimulate spontaneous HC regeneration and given doxycycline from P0-P7 to induce expression of N1ICD as well as LacZ for fate-mapping. We observed a 92% reduction in the number of fate-mapped regenerated HCs in mice with N1ICD overexpression compared to controls with HC damage but no manipulation of Notch signaling. Therefore, we conclude that increased Notch signaling prevents spontaneous HC regeneration from occurring in the neonatal mouse cochlea. Understanding which components of the Notch pathway regulates regenerative plasticity in the neonatal mouse cochlea will inform investigations focused on stimulating HC regeneration in mature cochlea and eventually in humans to treat hearing loss.

Oxytocin has a modulatory role in natural and drug reward processes. While the role of oxytocin in pair bonding and reproduction has been extensively studied, sex differences in conditioned and unconditioned behavioral responses to oxytocin treatment have not been fully characterized. Here, we determined whether male and female rats would show similar dose response curves in response to acute oxytocin on measures of locomotor activity, sucrose seeking, and sucrose intake. Male and freely cycling female rats received vehicle or oxytocin (0.1, 0.3, 1, 3 mg/kg, IP) injections before behavioral tests designed to assess general motor activity, as well as sucrose self-administration and seeking. Lower doses of oxytocin decreased motor activity in a novel environment in females relative to males. Likewise, lower doses of oxytocin in females decreased responding for sucrose during maintenance of sucrose self-administration and reinstatement to sucrose-conditioned cues. However, sucrose seeking in response to a sucrose prime was only decreased by the highest oxytocin dose in both sexes. In general, oxytocin had similar effects in both sexes. However, females were more sensitive to lower doses of oxytocin than males. These findings are consistent with the notion that oxytocin regulates many of the same behaviors in males and females, but that the effects are typically more profound in females. Therapeutic use of oxytocin should include sex as a factor in determining dose regimens.

A selective and sensitive liquid chromatography-tandem mass spectrometry method was developed and validated for investigating the pharmacokinetics of umbelliferone, apigenin, genkwanin and hydroxygenkwanin after oral administration of Daphne genkwa extract. Plasma samples were treated by protein precipitation with acetonitrile. Analytes were detected by triple-quadrupole MS/MS with an ESI source in negative selection reaction monitoring mode. The transitions of m/z 161 → 133 for umbelliferone, m/z 269 → 117 for apigenin, m/z 283 → 268 for genkwanin and m/z 299 → 284 for hydroxygenkwanin were confirmed for quantification. Chromatographic separation was conducted using an Eclipse XDB-C18 column, and the applied isocratic elution program allowed for simultaneous determination of the four analytes for a total run time of 2.5 min. The linearity was validated over the plasma concentration ranges of 1.421-1421 ng/mL for umbelliferone, 0.845-845 ng/mL for apigenin, 1.025-1025 ng/mL for genkwanin and 0.845-845 ng/mL for hydroxygenkwanin. The extraction recovery rate was >82.7% for each analyte. No apparent matrix effect was observed during the bioanalysis. After full validation, the proposed method was successfully applied to compare the pharmacokinetics of these analytes between normal and arthritic rats.

Withdrawal from cocaine regulates expression of distinct glutamate re-uptake transporters in the nucleus accumbens (NAc). In this study, we examined the cumulative effect of glutamate re-uptake by multiple excitatory amino acid transporters (EAATs) on drug-seeking at two different stages of withdrawal from self-administered cocaine. Rats were trained on fixed ratio 1 (FR1), progressing to FR5 schedule of reinforcement. After one day of withdrawal, microinfusion of a broad non-transportable EAAT antagonist, DL-threo-beta-benzyloxyaspartate (DL-TBOA), into the NAc shell dose-dependently attenuated self-administration of cocaine. Sucrose self-administration was not affected by DL-TBOA, indicating an effect specific to reinforcing properties of cocaine. The attenuating effect on cocaine seeking was not due to suppression of locomotor response, as DL-TBOA was found to transiently increase spontaneous locomotor activity. Previous studies have established a role for EAAT2-mediated re-uptake on reinstatement of cocaine seeking following extended withdrawal and extinction training. We found that blockade of NAc shell EAATs did not affect cocaine-primed reinstatement of cocaine seeking. These results indicate that behavioral history of withdrawal influences the effect of re-uptake mediated glutamate clearance on cocaine seeking. Dynamic regulation of glutamate availability by re-uptake mechanisms may impact other glutamate signaling pathways to account for such differences.

Numerous studies have shown that biochemical and behavioral effects of cocaine are mediated by dopamine D1 receptor (D1R) and NMDA R1 receptor (NR1)-mediated transmissions. In this study, we investigated the physical interactions between D1R and NR1 in response to acute cocaine administration in a time course of 5 minutes to 60 minutes. In the caudate-putamen (CPu) of male Fischer rats, a single cocaine injection (30 mg/kg) reduced D1R-NR1 protein-protein interactions 30 minutes after treatment. In addition, activation or blockade of the NMDA receptor using NMDA (25 mg/kg) or MK-801 (0.25 mg/kg), respectively, also reduced the D1R-NR1 physical interactions. Acute cocaine administration did not alter total D1R or NR1 protein levels in our time course of study. These results indicate that D1R-NR1 physical interaction rather than total protein levels may regulate the intracellular signaling after acute cocaine administration.

An extensive body of literature provides evidence for both sexual dimorphism and menstrual cycle effects in drug abuse patterns and behavioral responses. However, the cellular mechanisms underlying sexually dimorphic responses to and hormonal effects on cocaine use remain unclear. We hypothesized that endogenous hormonal fluctuations during the estrous cycle of rats modulate cocaine's effects on dopamine- and PKA-mediated intracellular responses. To test this hypothesis, intact female rats at different stages of their cycle received a single injection of saline or cocaine (20 mg/kg) and were sacrificed after 15 or 60 min. The nucleus accumbens (NAc) and caudate putamen (CPu) were dissected and analyzed via Western blot for total and phosphorylated (p-thr34) dopamine- and 3'-5'-cyclic AMP-regulated phosphoprotein with molecular weight 32 kDa (DARPP-32), PP1, PP2B (CNA1 and CNB1 subunits), PKA, CREB, cFOS, and Delta-FosB. Our results show that saline-treated rats had estrous cycle-related differences in protein levels of pCREB, DARPP-32, p-thr34-DARPP-32, PP1, and CNA1. Saline-treated female rats in the estrus stage had higher levels of pCREB in the NAc, but cocaine-treatment lowered pCREB levels. The estrous cycle also significantly affected the magnitude of change for p-thr34-DARPP-32 protein levels in both the NAc and CPu. Sixty minutes of cocaine administration increased p-thr34-DARPP-32 levels in the NAc of rats during estrus and proestrus and in the CPu of rats in diestrus. Furthermore, cocaine-induced changes in PP1 protein levels in the NAc were also affected by the stage of the cycle; 60 min of cocaine administration increased PP1 levels in the NAc of rats during diestrus, whereas PP-1 levels decreased in rats during estrus. Taken together, these novel findings suggest that hormonal fluctuations during the estrous cycle may contribute to the previously reported sex differences in the PKA pathway and in behavioral responses to cocaine.