Blue-Light-Activated Water-Soluble Sn(IV)-Porphyrins for Antibacterial Photodynamic Therapy (aPDT) against Drug-Resistant Bacterial Pathogens.

Antimicrobial resistance has emerged as a global threat to the treatment of infectious diseases. Antibacterial photodynamic therapy (aPDT) is a promising alternative approach and is highly suitable for the treatment of cutaneous bacterial infections through topical applications. aPDT relies on light-responsive compounds called photosensitizer (PS) dyes, which generate reactive oxygen species (ROS) when induced by light, thereby killing bacterial cells. Despite several previous studies in this area, the molecular details of targeting and cell death mediated by PS dyes are poorly understood. In this study, we further investigate the antibacterial properties of two water-soluble Sn(IV) tetrapyridylporphyrins that were quaternized with methyl and hexyl groups (1 and 2). In this follow-up study, we demonstrate that Sn(IV)-porphyrins can be photoexcited by blue light (a 427 nm LED) and exhibit various levels of bactericidal activity against both Gram-(+) and Gram-(-) strains of bacteria. Using localization studies through fluorescence microscopy, we show that 2 targets the bacterial membrane more effectively than 1 and exhibits comparatively higher aPDT activity. Using multiple fluorescence reporters, we demonstrate that photoactivation of 1 and 2 results in extensive collateral damage to the bacterial cells including DNA cleavage, membrane damage, and delocalization of central systems necessary for bacterial growth and division. In summary, this investigation provides deep insights into the mechanism of bacterial killing mediated by the Sn(IV)-porphyrins. Moreover, our approach offers a new method for evaluating the activity of PS, which may inspire the discovery of new PS with enhanced aPDT activity.

Synthesis and in vitro cytotoxicity study of three di-organotin(IV) Schiff base di-acylhydrazone complexes.

Three di-organotin(IV) complexes have been synthesized by the reaction of Schiff base di-acylhydrazone ligands bis(5-chlorosalicylaldehyde) adipoylhydrazone and R2SnCl2 [R = Me (1), Ph (2), n-Bu (3)]. Structures of all complexes were characterized by 1H, 13C, 119Sn NMR, elemental analysis, IR and mass spectrometry. Experimental results showed that the symmetric diacylhydrazone ligands coordinate the tin atom in a hexadentate form, where the tin atom shows a penta-coordination, in a distorted triangular bipyramid geometry. Using MTT method, in vitro cytotoxicity of three complexes was determined against three cancer cell lines (A549, HeLa, HepG-2). Studies reveal that complex 3 showed the strongest cytotoxic activity among the three complexes, which may be correlated with the generation of intracellular reactive oxygen species. Uptake of complex 3 into cells and promotion of reactive oxygen species were visualized by confocal fluorescence imaging.

Speciation of tin ions in oxide glass containing iron oxide through solvent extraction and inductively coupled plasma atomic emission spectrometry after the decomposition utilizing ascorbic acid.

Determining the concentrations of different Sn ions in glass containing iron oxide by wet chemical analysis is a challenge because a redox reaction occurs between Sn2+ and Fe3+. A chemical analysis method for determining the concentrations of Sn2+ and Sn4+ in soda lime glass containing iron oxide was proposed. A mixture of ascorbic acid, hydrochloric acid, and hydrofluoric acid was used to decompose the sample in a vessel with nitrogen flow. Ascorbic acid functioned as a reductant for Fe3+. Subsequently, the Sn2+ were separated as a diethyldithiocarbamate complex. Furthermore, inductively coupled plasma atomic emission spectroscopy was used to determine the concentrations of Sn4+ and total Sn, from which the concentration of Sn2+ can be calculated. The results were validated by comparing ratios of Sn2+ to total Sn to results obtained using Mössbauer spectroscopy. The results were in agreement, thereby validating the use of the proposed approach.

In vitro DNA binding, pBR322 cleavage and molecular docking studies of 1,2-diaminobenzene, dichloro glycyl glycinate tin(IV) and zirconium(IV) complexes.

De novo design and synthesis of complexes 1,2-diaminobenzene, dichloro glycyl glycinate tin(IV) and zirconium(IV), 1 and 2 as molecular drug entities were carried out. The structure elucidation of 1 and 2 was done by analytical techniques and spectroscopic methods viz. IR, UV-vis, 1H, 13C, 119Sn NMR, ESI-Mass and XRD techniques. In vitro DNA binding studies of 1 and 2 by various biophysical techniques viz electronic absorption, emission spectroscopy and circular dichroism measurements were carried out to evaluate their potential to act as chemotherapeutic candidates; furthermore, cleavage studies with pBR322plasmid DNA and computer-aided molecular docking studies were also done to study the mechanistic pathway and mode of binding at the molecular level. The observed results revealed that complex 1 exhibited greater DNA binding propensity in contrast to complex 2 primarily via electrostatic binding mode. The pBR322 DNA cleavage studies of both the complexes revealed the hydrolytic cleavage mechanism and DNA minor groove binding, which was ascertained by molecular docking studies of the drug candidate. Communicated by Ramaswamy H. Sarma.

Tin Carboxylate Complexes of Natural Bacteriochlorin for Combined Photodynamic and Chemotherapy of Cancer è.

Photodynamic therapy (PDT) is currently one of the most promising methods of cancer treatment. However, this method has some limitations, including a small depth of penetration into biological tissues, the low selectivity of accumulation, and hypoxia of the tumor tissues. These disadvantages can be overcome by combining PDT with other methods of treatment, such as radiation therapy, neutron capture therapy, chemotherapy, etc. In this work, potential drugs were obtained for the first time, the molecules of which contain both photodynamic and chemotherapeutic pharmacophores. A derivative of natural bacteriochlorophyll a with a tin IV complex, which has chemotherapeutic activity, acts as an agent for PDT. This work presents an original method for obtaining agents of combined action, the structure of which is confirmed by various physicochemical methods of analysis. The method of molecular modeling was used to investigate the binding of the proposed drugs to DNA. In vitro biological tests were carried out on several lines of tumor cells: Hela, A549, S37, MCF7, and PC-3. It was shown that the proposed conjugates of binary action for some cell lines had a dark cytotoxicity that was significantly higher (8-10 times) than the corresponding metal complexes of amino acids, which was explained by the targeted chemotherapeutic action of the tin (IV) complex due to chlorin. The greatest increase in efficiency relative to the initial dipropoxy-BPI was found for the conjugate with lysine as a chelator of the tin cation relative to cell lines, with the following results: S-37 increased 3-fold, MCF-7 3-fold, and Hela 2.4-fold. The intracellular distribution of the obtained agents was also studied by confocal microscopy and showed a diffuse granular distribution with predominant accumulation in the near nuclear region.

Low Mg content on Ti-Nb-Sn alloy when in contact with eBMMSCs promotes improvement of its biological functions.

Magnesium is a metal used in the composition of titanium alloys and imparts porosity. Due to its osteoconductive, biocompatible and biodegradable characteristics, its application in the development of biomedical materials has become attractive. This study aimed to evaluate the influence of magnesium present in porous Ti-Nb-Sn alloys, which have a low elastic modulus in adhesive, osteogenic properties and the amount of reactive intracellular oxygen species released in mesenchymal stem cells derived from bone marrow equine bone (eBMMSCs). Mechanical properties of the alloy, such as hardness, compressive strength and elastic modulus, were analyzed, as well as surface morphological characteristics through scanning electron microscopy. The evaluation of magnesium ion release was performed by atomic force spectroscopy. The biological characteristics of the alloy, when in contact with the alloy surface and with the culture medium conditioned with the alloy, were studied by SEM and optical microscopy. Confirmation of osteogenic differentiation by alizarin red and detection of ROS using a Muse® Oxidative Stress Kit based on dihydroetide (DHE). The alloy showed an elastic modulus close to cortical bone values. The hardness was close to commercial Ti grade 2, and the compressive strength was greater than the value of cortical bone. The eBMMSCs adhered to the surface of the alloy during the experimental time. Osteogenic differentiation was observed with the treatment of eBMMMSCs with conditioned medium. The eBMMSCs treated with conditioned medium decreased ROS production, indicating a possible antioxidant defense potential of magnesium release.

Tin derived antimony/nitrogen-doped porous carbon (Sb/NPC) composite for electrochemical sensing of albumin from hepatocellular carcinoma patients.

An electrochemical sensor based on an antimony/nitrogen-doped porous carbon (Sb/NPC) composite has been developed for the quantitative detection of albumin from hepatocellular carcinoma (HCC) patients. Sb/NPC is hydrothermally synthesized from Sn/NPC precursors. The synthesized precursor (Sn/NPC) and the product (Sb/NPC) are characterized by XRD, FTIR, TGA, UV/Vis, SEM, and AFM. Cyclic voltammetry, chronoamperometry, and electrochemical impedance studies are used to investigate the electrochemical performance of Sb/NPC-GCE. Sb/NPC-GCE detects albumin at physiological pH of 7.4 in the potential range 0.92 V and 0.09 V for oxidation and reduction, respectively. LOD and recovery of Sb/NPC-GCE for the determination of albumin are 0.13 ng.mL-1 and 66.6 ± 0.97-100 ± 2.73%, respectively. Chronoamperometry of the modified working electrode demonstrates its stability for 14 h, indicating its reusability and reproducibility. Sb/NPC-GCE is a selective sensor for albumin detection in the presence of interfering species. The electrode has been applied for albumin detection in human serum samples of HCC patients. A negative correlation of albumin with alpha-fetoprotein levels in HCC patients is observed by statistical analysis.

The Effect of Plant Essential Oil and Extracts on Fatty Acid Profile of Virgin Olive Oil Stored in Different Packaging Materials.

In this study, the combined effect of different packaging materials (transparent PET, transparent glass, glass-PET bottle and tin), some aromatic herbs (thyme, rosemary, sage and olive leaf) and also their essential oils (thyme, rosemary and sage) on fatty acid composition of virgin olive oil was investigated during storage period. The initial amounts of the main fatty acids as oleic, palmitic and linoleic acids were determined as 72.89%, 11.89% and 8.96%, respectively. The addition of aromatic plants and essential oils did not effect the fatty acid profile. Also, packaging materials had a minor influence on fatty acids. In the 6th month of storage, the oleic acid contents of olive oils showed the increase in all of samples. The highest increase was observed in olive oil stored in glass-PET (74.30-75.01%), followed by stored in glass bottle (73.41-74.82%). Generally, during the storage, the differences of fatty acid contents were in minor level. The fatty acid composition of olive oils stored under different essential oil and extract concentrations showed partial differences depending on the extract type and concentration.

Synergetic anticancer activity of gold porphyrin appended to phenyl tin malonate organometallic complexes.

The discovery of novel anticancer chemotherapeutics is fundamental to treat cancer more efficiently. Towards this goal, two dyads consisting of a gold porphyrin appended to organotin(iv) entities were synthesized and their physicochemical and biological properties were characterized. One dyad contains a gold porphyrin connected to a tin(iv) cation via a malonate and two phenyl ligands (AuP-SnPh2), while the other contains two tin(iv) cations each chelated to one carboxylic acid group of the malonate and three phenyl ligands (AuP-Sn2Ph6). The mode of chelation of Sn(iv) to the malonate was elucidated by IR spectroscopy and 119Sn NMR. In the solid state, the complexes exist as coordination polymers in which the tin is penta-coordinated and bridged to two different malonate units. In solution the chemical shifts of 119Sn signals indicate that the tin complexes are in the form of monomeric species associated with a tetra-coordinated tin cation. The therapeutic potential of these new compounds was assessed by determining their cytotoxic activities on human breast cancer cells (MCF-7) and on healthy human fibroblasts (FS 20-68). The study reveals that the dyads are more potent anticancer drugs than the mixture of their individual components (gold porphyrin and reference tin complexes). Therefore, the covalent link of organotin complexes to a gold porphyrin induces a synergistic cytotoxic effect. The dyad AuP-SnPh2 shows high cytotoxicity (0.13 µM) against MCF-7 along with good selectivity for cancer cells versus healthy cells. Finally, it was also shown that the dyad AuP-Sn2Ph6 exhibits a very high anticancer activity (LC50 = 0.024 µM), but the presence of two tin units induces strong cytotoxicity on healthy cells too (LC50 = 0.032 µM). This study underscores, thus, the potential of the association of gold porphyrin and organotin complexes to develop anticancer metallo-drugs.

Photodynamic activity of Sn(IV) tetrathien-2-ylchlorin against MCF-7 breast cancer cells.

A new readily-synthesized Sn(iv) tetraarylchlorin with thien-2-yl substituents (SnC) has been prepared and fully characterized by various spectroscopic techniques and its photophysical and photochemical properties, such as the singlet oxygen quantum yield (ΦΔ), fluorescence quantum yield (ΦF), triplet lifetime (τT) and photostability, have been evaluated. SnC has an unusually high ΦΔ value of 0.89 in DMF. Studies on the photodynamic activity against MCF-7 breast cancer cells exhibited a very low IC50 value of 0.9 µM and high phototoxicity (dark versus light) indices of >27.8 after irradiation with a 660 nm Thorlabs LED (280 mW cm-2). The results demonstrate that Sn(iv) tetraarylchlorins of this type are suitable candidates for further in-depth PDT studies.

Tin, Titanium, Tantalum, Vanadium and Niobium Oxide Based Sensors to Detect Colorectal Cancer Exhalations in Blood Samples.

User-friendly, low-cost equipment for preventive screening of severe or deadly pathologies are one of the most sought devices by the National Health Services, as they allow early disease detection and treatment, often avoiding its degeneration. In recent years more and more research groups are developing devices aimed at these goals employing gas sensors. Here, nanostructured chemoresistive metal oxide (MOX) sensors were employed in a patented prototype aimed to detect volatile organic compounds (VOCs), exhaled by blood samples collected from patients affected by colorectal cancer and from healthy subjects as a control. Four sensors, carefully selected after many years of laboratory tests on biological samples (cultured cells, human stools, human biopsies, etc.), were based here on various percentages of tin, tungsten, titanium, niobium, tantalum and vanadium oxides. Sensor voltage responses were statistically analyzed also with the receiver operating characteristic (ROC) curves, that allowed the identification of the cut-off discriminating between healthy and tumor affected subjects for each sensor, leading to an estimate of sensitivity and specificity parameters. ROC analysis demonstrated that sensors employing tin and titanium oxides decorated with gold nanoparticles gave sensitivities up to 80% yet with a specificity of 70%.

Simple Colorimetric and Fluorescence Chemosensing Probe for Selective Detection of Sn2+ Ions in an Aqueous Solution: Evaluation of the Novel Sensing Mechanism and Its Bioimaging Applications.

An easily accessible colorimetric and fluorescence probe 4-((3-chloro-1,4-dioxo-1,4-dihydronaphthalen-2-yl)amino)benzenesulfonamide (4CBS) was successfully developed for the selective and sensitive detection of Sn2+ in an aqueous solution. The sensing mechanism involves reduction of -C═O into -C-OH groups in 4CBS upon the addition of Sn2+, which initiates the fluorescence turn-on mode. A better linear relationship was achieved between fluorescence intensity and Sn2+ concentration in the range of 0-62.5 µM, with a detection limit (LOD) of 0.115 µM. The binding mechanism of 4CBS for Sn2+ was confirmed by Fourier transform infrared analysis, NMR titrations, and mass (electrospray ionization) spectral analysis. Likewise, the proposed sensing mechanism was supported by quantum chemical calculations. Moreover, bioimaging studies demonstrated that the chemosensing probe 4CBS is an effective fluorescent marker for the detection of Sn2+ in living cells and zebrafish. Significantly, 4CBS was able to discriminate between Sn2+ in human cancer cells and Sn2+ in normal live cells.

Sn(IV) N-confused porphyrins as photosensitizer dyes for photodynamic therapy in the near IR region.

The utility of Sn(iv) N-confused porphyrin (SnNCP) for use as photosensitizer dyes in photodynamic therapy is investigated. SnNCP has an unusually high singlet oxygen quantum yield of 0.72 in DMSO. IC50 values of 1.6 and 12.8 µM were obtained against MCF-7 cells upon irradiation with 660 and 780 nm LEDs.

Development of 68Ga-labeled tin colloids for evaluating phagocytic function of Kupffer cells using preclinical PET imaging.

OBJECTIVE: This study aimed to investigate the optimal conditions for producing 68Ga-labeled tin colloid and the feasibility of 68Ga-tin colloid positron emission tomography (PET) for visualization and evaluation of the phagocytic function of Kupffer cells (KCs) in vivo. METHODS: 68Ga-tin colloid was prepared by adding tin solution (1 mM, 0.2 mL) to 68Ga solution (1.0 mL), followed by pH adjustment with sodium acetate (1 M, 0.2 mL). Various labeling times were tested to find the optimal one. Colloid size was measured by filtering the solution through three-ply membrane filters (with pore sizes of 200, 3000, and 5000 nm), and radioactivity was measured in the whole filtrate and the filters using a gamma counter. The in vitro stability of the colloid was evaluated by the size measurement after incubation under ambient conditions for up to 60 min. PET scanning was performed for 30 min after intravenous administration of 68Ga-tin colloid solution (4 MBq) to healthy rats. Time-activity-curves for the liver, spleen, and blood pool were generated. Finally, liver uptake was compared before and after the establishment of KC-depletion and non-alcoholic steatohepatitis (NASH) rat models. RESULTS: Colloid size increased with increasing labeling time. After pH adjustment, the colloid sizes remained nearly unchanged. The optimal labeling time was determined as 30 min. PET imaging of healthy rats revealed that liver uptake of the 68Ga-tin colloid increased with increasing colloid size. In KC-depleted rats, liver uptake significantly decreased (n = 4, p < 0.01). NASH model rats showed significantly decreased uptake of 68Ga-tin colloid in the livers (n = 5, p < 0.01). CONCLUSIONS: 68Ga-tin colloid, prepared by a simple radiolabeling method, enabled in vivo PET imaging to evaluate the phagocytic function of KCs.

An octabrominated Sn(iv) tetraisopropylporphyrin as a photosensitizer dye for singlet oxygen biomedical applications.

Two novel Sn(iv) tetraisopropylphenylporphyrins have been synthesized to explore the effect of octabromination at the ß-pyrrole positions on their photophysical properties and photodynamic activity. The lower energy Q band of an octabrominated complex lies at 675 nm well within the therapeutic window. The octabrominated dye has a relatively high singlet oxygen quantum yield of 0.78 in DMF and exhibits favorable photodynamic activity against MCF-7 cells with an IC50 value of 10.7 µM and a 5.74 log reduction value (5 µM) towards S. aureus under illumination at 660 nm for 60 min with a Thorlabs M660L3 LED (280 mW cm-2).

Novel triorganotin complexes based on phosphonic acid ligands: Syntheses, structures and in vitro cytostatic activity.

Six novel organotin phosphonate complexes, [(Me3Sn)4(HL1)4]n1, [(Me3Sn)2(HL2)2]n2, [(Me3Sn)2L3(H2O)]n3, [(Ph3Sn)(HL1)]64, [(Ph3Sn)2L2]n5 and [(Ph3Sn)2L3]66, derived from phosphonic acid ligands [NaHL1 = 1-C10H7OPO2(OH)Na, H2L2 = 1-C10H7PO(OH)2, H2L3 = 2-C10H7PO(OH)2], have been synthesized and characterized by elemental analysis, FT-IR, NMR (1H, 13C, 31P and 119Sn) spectroscopy and X-ray crystallography. The structural analysis reveals that complexes 1 and 5 display 1D infinite zig-zag chain structures, and complex 2 shows 1D right-handed helical chain structure, while complex 3 displays 1D left-handed helical chain structure. Complexes 4 and 6 are 24-membered macrocyclic rings interconnected by P, O and Sn atoms. Additionally, the molecules of complexes 1 and 3 are further linked through intermolecular π···π and O-H···O interaction into supramolecular structures, respectively. Furthermore, we preliminarily estimated in vitro cytostatic activity of complexes 1-6 against the human cervix tumor cells (HeLa), human hepatocellular carcinoma cells (HepG-2) and human normal breast cells (HBL-100). Importantly, the anti-proliferative properties and possible pathway of complex 6 are investigated, and the results demonstrate that complex 6 could induce apoptotic cell death via an overload of intracellular reactive oxygen species (ROS) levels and the dysfunctional depolarization of mitochondrial membranes.

Anticandidal and In vitro Anti-Proliferative Activity of Sonochemically synthesized Indium Tin Oxide Nanoparticles.

The present work demonstrates the synthesis, characterization and biological activities of different concentrations of tin doped indium oxide nanoparticles (Sn doped In2O3 NPs), i.e., (Sn/In = 5%, 10% and 15%). We have synthesized different size (38.11 nm, 18.46 nm and 10.21 nm) of Sn doped In2O3 NPs. by using an ultra-sonication process. The Sn doped In2O3 NPs were characterized by by x-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) which confirmed the successful doping of tin (Sn) with Indium oxide (In2O3). Anticandidal activity was performed by standard agar dilution method using Candida albicans for the study. The minimum inhibitory/fungicidal concentration (MIC/MFC) values recorded were, 8 & >8 mg/ml for pure In2O3 NPs, 4 & 8 mg/ml for 5%, 2 & 8 mg/ml for 10%, whereas 1 & >4 mg/ml for 15% Sn doped In2O3 NPs, respectively. The topographical alteration caused by Sn doped In2O3 NPs on Candida cells, was clearly observed by SEM examination. A significant enhancement in anticandidal activity was seen, when Candida cells were exposed to (Sn/In = 5%, 10% and 15%). Moreover, we have also evaluated the impact of Sn-In2O3 NPs on human colorectal carcinoma cells (HCT-116). The results demonstrated that Sn-In2O3 NPs (Sn/In = 5%, 10% and 15%), caused dose dependent decrease in the cancer cell viability as the low dosage (2.0 mg/mL) showed 62.11% cell viability, while 4.0, 8.0, 16.0, 32.0 mg/mL dosages showed 20.45%, 18.25%, 16.58%, and 15.58% cell viability. In addition, the treatment of Sn-In2O3 NPs also showed significant cellular and anatomical changes in cancer cells as examined by microscopes. We have also examined the impact of Sn-In2O3 NPs (5%, 10%, 15%) on normal cells (HEK-293) and the results demonstrate that Sn-In2O3 NPs did not reduce the cell viability of normal cells.

Gamma radiation shielding properties of some Bi-Sn-Zn alloys.

We investigate the gamma radiation shielding properties of some Bi-Sn-Zn alloys. For this study, we synthesised five bismuth-based lead-free alloy samples using the melt quench technique with the composition Bi50Sn[Formula: see text]Zn[Formula: see text] where [Formula: see text] Apart from physical parameters such as the weight, density, and thickness of the alloy samples, we estimated their optimum thickness range at photon energies of 122, 511, 662, and 1250 keV. The mass attenuation coefficients and effective atomic number, measured experimentally, were found to be in close agreement with values computed using WinXCom software, within a ± 4% error. From the transmitted photon spectra, the radiation protection efficiency (RPE) was determined and analysed for different alloy compositions. A correlation between RPE and effective atomic number was established at different photon energies. The Bi50Sn50 binary alloy composition is reported to exhibit maximum shielding efficiency.

A dual mode photoelectrochemical sensor for nitrobenzene and L-cysteine based on 3D flower-like Cu2SnS3@SnS2 double interfacial heterojunction photoelectrode.

In this work, 3D hierarchical Cu2SnS3@SnS2 flower assembled from nanopetals with sandwich-like Cu2SnS3-SnS2-Cu2SnS3 double interfacial heterojunction was successfully designed and synthesized on fluoride doped tin oxide (FTO) for photoelectrochemical (PEC) sensor by in situ electrodeposition p-type Cu2SnS3 nanoparticles on both inner and outer surfaces of n-type SnS2 nanopetals. The unique double interfacial heterojunction simultaneously combines 3D flower-like architectures to drastically increase the light trapping and absorption in visible-near infrared range (Vis-NIR), and dramatically inhibites the charge carrier recombination, which is crucial for boosting the PEC activity. Benefitting from the shape and compositional merits, the Cu2SnS3@SnS2 heterojunction possess dual-mode signal by controlling the electrodeposition time to manipulate the composition ratio of Cu2SnS3 and SnS2. The Cu2SnS3@SnS2/FTO electrode not only exhibits excellent photoeletro-reduction capacity for ultra-sensitive sensing trace persistent organic pollutant (nitrobenzene, NB), but also presents photoeletro-oxidization activity for high selective detection of L-cysteine (L-Cys) without any auxiliary enzyme under the light illumination. Dual mode sensor displayed superb performance for the detection of NB/L-Cys, showing a wide linear range from 100 pM to 300 µM/10 nM to 100 µM and a low detection limit (3S/N) of 68 pM/8.5 nM, respectively. Such a tunable double interfacial heterojunction design opened up new avenue for constructing multifunction PEC sensing platform.

Synthesis and characterization of heterobimetallic SnIV-CuII/ZnII complexes: DFT studies, cleavage potential and cytotoxic activity.

Heterobimetallic complexes [Cu(L)Sn(CH3)2(H2O)(Cl)] (3) and [Zn(L)Sn(CH3)2(H2O)(Cl)] (4) have been synthesized from their monometallic analogs [Cu(L)(H2O)(Cl)] (1) and [Zn(L)(H2O)(Cl)] (2) of Schiff base ligand (L) which were characterized by various spectroscopic and analytical methods. DFT calculations were carried out to simulate the vibrational spectra to support the anticipated structures. The interaction studies of ligand (L) and complexes (1-4) with CT-DNA were performed by employing UV-vis, and fluorescence spectroscopic techniques which revealed that heterobimetallic complexes 3 and 4 showed higher affinity with DNA due to dual mode of action as compared to monometallic complexes 1 and 2. Further, validation of the interaction studies was accomplished by carrying out molecular docking studies with DNA. Gel assay displayed that both the complexes have ability to cleave DNA efficiently and are specific minor groove binders. CuII-SnIV complex 3 cleaved pBR322 DNA via oxidative mechanism, while ZnII-SnIV complex 4 followed hydrolytic cleavage pathway. In vitro cytotoxicity evaluation of complex 3 was tested on a different cancer cell lines showing promising antitumor activity.Communicated by Ramaswamy H. Sarma.