Arindam Pramanik

A novel study of antibacterial activity of copper iodide nanoparticle mediated by DNA and membrane damage.

In this article potential activity of nanoparticles (NPs) of copper iodide (CuI) as an antibacterial agent has been presented. The nano particles are synthesized by co-precipitation method with an average size of 8 nm as determined by Transmission Electron Microscope (TEM). The average charge of the NPs is -21.5 mV at pH 7 as obtained by zeta potential measurement and purity is determined by XRD. These NPs are able to kill both gram positive and gram negative bacteria. Among the bacteria tested, DH5α is more sensitive but Bacillus subtilis is more resistant to NPs of CuI. Consequently, the MIC and MBC values of DH5α is least (0.066 mg/ml and 0.083 mg/ml respectively) and B. subtilis is highest (0.15 mg/ml and 0.18 mg/ml respectively) among the tested bacterial strains. From our studies it is inferred that CuI NPs produce reactive oxygen species (ROS) in both gram negative and gram positive bacteria and it also causes ROS mediated DNA damage for the suppression of transcription as revealed by reporter gene assay. Probably ROS is formed on the surface of NPs of CuI in presence of amine functional groups of various biological molecules. Furthermore they induce membrane damage as determined by atomic force microscopy (AFM). Thus production of ROS and membrane damage are major mechanisms of the bactericidal activity of these NPs of CuI.

Interplay between autophagy and apoptosis mediated by copper oxide nanoparticles in human breast cancer cells MCF7.

BACKGROUND Metal oxide nanoparticles are well known to generate oxidative stress and deregulate normal cellular activities. Among these, transition metals copper oxide nanoparticles (CuO NPs) are more compelling than others and able to modulate different cellular responses. METHODS In this work, we have synthesized and characterized CuO NPs by various biophysical methods. These CuO NPs (~30nm) induce autophagy in human breast cancer cell line, MCF7 in a time- and dose-dependent manner. Cellular autophagy was tested by MDC staining, induction of green fluorescent protein-light chain 3 (GFP-LC3B) foci by confocal microscopy, transfection of pBABE-puro mCherry-EGFP-LC3B plasmid and Western blotting of autophagy marker proteins LC3B, beclin1 and ATG5. Further, inhibition of autophagy by 3-MA decreased LD50 doses of CuO NPs. Such cell death was associated with the induction of apoptosis as revealed by FACS analysis, cleavage of PARP, de-phosphorylation of Bad and increased cleavage product of caspase 3. siRNA mediated inhibition of autophagy related gene beclin1 also demonstrated similar results. Finally induction of apoptosis by 3-MA in CuO NP treated cells was observed by TEM. RESULTS This study indicates that CuO NPs are a potent inducer of autophagy which may be a cellular defense against the CuO NP mediated toxicity and inhibition of autophagy switches the cellular response into apoptosis. CONCLUSIONS A combination of CuO NPs with the autophagy inhibitor is essential to induce apoptosis in breast cancer cells. GENERAL SIGNIFICANCE CuO NP induced autophagy is a survival strategy of MCF7 cells and inhibition of autophagy renders cellular fate to apoptosis.

Synthesis of highly fluorescent nitrogen and phosphorus doped carbon dots for the detection of Fe3+ ions in cancer cells

Highly fluorescent nitrogen and phosphorus-doped carbon dots with a quantum yield 59% have been successfully synthesized from citric acid and di-ammonium hydrogen phosphate by single step hydrothermal method. The synthesized carbon dots have high solubility as well as stability in aqueous medium. The as-obtained carbon dots are well monodispersed with particle sizes 1.5-4 nm. Owing to a good tunable fluorescence property and biocompatibility, the carbon dots were applied for intercellular sensing of Fe(3+) ions as well as cancer cell imaging.

Al3+ selective coumarin based reversible chemosensor: application in living cell imaging and as integrated molecular logic gate

An efficient coumarin based fluorescent ‘turn-on’ receptor (H2L) for the detection of Al3+ has been synthesized following simple Schiff base condensation of 4-hydroxy-3-acetylcoumarin with 2-amino-4-methylphenol. The receptor H2L shows about 21 fold increase in fluorescence intensity upon addition of Al3+ than in the case of other metals. The limit of detection is 0.39 μM. H2L is efficient in detecting Al3+ in the intracellular region of human cervical cancer cells and also exhibits an INHIBIT logic gate with Al3+ and EDTA as chemical inputs by monitoring both the absorption as well as emission mode. Theoretical calculations (DFT and TDDFT) are applied to interpret the sensing mechanism of the synthesized receptor.

Detection of total count of Staphylococcus aureus using anti-toxin antibody labelled gold magnetite nanocomposites: a novel tool for capture, detection and bacterial separation

In this contribution, we demonstrate a rapid, sensitive, specific and efficient method for detection ofStaphylococcus aureus (S. aureus) as the model analyte at ultra-low concentrations using antibody labelled multifunctional gold-magnetite nanocomposites. A simple and efficient approach was adopted to construct diverse multifunctional gold magnetite nanostructures using 2,2′-(ethylenedioxy)-bis-(ethylamine) (EDBE) as a linker. The gold magnetite nanostructures were fabricated by iterative deposition of gold nanoparticles on the previously decorated gold-seed stabilized magnetite nanoparticles. These nanocomposites were further bioconjugated with an anti-α-toxin antibody with the aim to generate biorecognition probes that can specifically allow ultrasensitive detection as well as removal of S. aureus at ultra-low concentrations. The fluorescence and optical images of bacterial cells after interaction with our bioprobes showed that the pathogenic bacteria could be first immunomagnetically captured, detected and removed from S. aureuscell suspension in 30 min within the range of 102–107 CFU mL−1 of bacterial concentration. The detection limit achieved of S. aureus was 102 CFU mL−1. The specificity of the detection ofS. aureus was also verified using Escherichia coli as the model analyte using confocal microscopy. The combined functionalities of such antibody-targeted nanoprobes can be considered as a new tool box for the targeted, specific and sensitive detection of specific organisms (S. aureus) within 30 min.

A novel drug “copper acetylacetonate” loaded in folic acid-tagged chitosan nanoparticle for efficient cancer cell targeting

Abstract Several copper compounds have proven anti-cancer activity. Similarly, curcumin a derivative of 1,3 diketone, which is not plenty in nature, has comparable anti-cancer activity. In this work, we have explored the synergistic anti-cancer activity of copper ion and acetylacetone complex containing 1,3 diketone group. The cytotoxicity of the copper acetylacetonate (CuAA) complex was evaluated on various cancer cells and LD50 doses were determined. To investigate the mechanism, various biochemical assays were performed and reactive oxygen species as well as the glutathione level in the cell were found to be increased after the treatment with the above-mentioned complex. Further this reagent induced apoptosis and reduced mitochondrial membrane potential of the cells. Because of the poor solubility and reasonable cytotoxicity of CuAA, polymer nanoparticles (NPs) of chitosan derivatives were used for delivery in cancer cells. For the targeted delivery, folic acid-tagged hydrophobic-modified chitosan NPs were developed and the CuAA was encapsulated. Finally, these drug-encapsulated NPs were successfully delivered to folate receptor over-expressed cancer cells. Thus using nanotechnology, we developed an anti-cancer agent suitable for targeted delivery.

Evaluation of copper iodide and copper phosphate nanoparticles for their potential cytotoxic effect

To explore the potential biological activities of transition metal-based nanoparticles (NPs), we synthesized two copper-based NPs, CuI and Cu3(PO4)2. The structural features of these NPs were determined by the X-ray diffraction (XRD), dynamic light scattering (DLS) and transmission electron microscopy (TEM). The size of CuI and Cu3(PO4)2 NPs were 35 ± 4.2 nm and 67 ± 6.3 nm respectively as determined by TEM. Cell viability, generation of reactive oxygen species (ROS), cell cycle and induction of apoptosis were assessed on human breast cancer cell line MCF7 after the treatment of these NPs. Exposure of CuI and Cu3(PO4)2 NPs decreased cell viability in a dose-dependent manner. Also, CuI NPs produced more ROS compared to Cu3(PO4)2 and presence of N-acetyl cysteine (NAC) along with NPs increased the cell survival. Cell cycle analysis indicated that after exposure of these NPs at their respective LD50 doses increased Sub G1 and G2/M peak after 8 h and 24 h of treatment respectively. Apoptosis study by AnnexinV-FITC staining showed slight increased in the early and late apoptosis after 8 h of treatment and most of the cells were dead after 24 h of treatment. Thus our observations suggest that the exposure of these two NPs induced dose-dependent cytotoxicity on MCF7 cell that is associated with ROS-mediated apoptosis.

Folic acid modified copper oxide nanoparticles for targeted delivery in in vitro and in vivo systems

Copper oxide nanoparticles are known to exhibit toxic effects on a variety of cell types. In the present study, copper oxide nanoparticles were modified with folic acid for targeted delivery. The physicochemical properties of copper oxide nanoparticles (CuO NPs) and folic acid conjugated copper oxide nanoparticles (CuO–FA NPs) were studied by Dynamic light scattering (DLS), Field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared spectroscopy (FTIR). To determine targeting efficacy, we have used folate receptor positive and folate receptor knock down human breast cancer cells MCF7. Flow cytometric analysis, generation of ROS and expression of apoptotic proteins (cleaved PARP, decreased p-BAD) indicated that most cell death occurred through apoptosis in CuO–FA NPs treated MCF7 cells. In the in vivo study, we used Daltons lymphoma (DL) cell induced tumor in mice. We successfully delivered CuO and CuO–FA NPs through peritoneal injection after induction of the tumor. Reactive oxygen species (ROS), glutathione (GSH) was measured in DL cells isolated from tumor bearing mice. All of these data indicated that CuO–FA NPs was more effective in killing the tumor cells and successful reduction of the tumor was observed in CuO–FA NPs treated mice after 15 days of treatment. These findings have important implications for understanding the potential anticancer properties induced by folic acid modified CuO NPs.

A spatio-temporal cardiomyocyte targeted vector system for efficient delivery of therapeutic payloads to regress cardiac hypertrophy abating bystander effect

Diverse array of therapeutic regimens, drugs or siRNA, are commonly used to regress cardiac hypertrophy, although, bystander effect and lower retention of bioactive molecules significantly reduce their functional clinical efficacy. Carvedilol, a widely used and effective anti-hypertrophic drug, simultaneously blocks β-adrenergic receptors non-specifically in various organs. Likewise, non-specific genome-wide downregulation of p53 expression by specific siRNA efficiently abrogates cardiac hypertrophy but results in extensive tumorigenesis affecting bystander organs. Therefore, delivery of such therapeutics had been a challenge in treating cardiovascular dysfunction. Cardiac tissue engineering was successfully accomplished in this study, by encapsulating such bioactive molecules with a stearic acid modified Carboxymethyl chitosan (CMC) nanopolymer conjugated to a homing peptide for delivery to hypertrophied cardiomyocytes in vivo. The peptide precisely targeted cardiomyocytes while CMC served as the vector mediator to pathological myocardium. Controlled delivery of active therapeutic payloads within cardiomyocytes resulted in effective regression of cardiac hypertrophy. Thus, this novel nano-construct as a spatio-temporal vector would be a potential tool for developing effective therapeutic strategies within cardiac micro-environment via targeted knockdown of causal genes.

Targeted delivery of “copper carbonate” nanoparticles to cancer cells in vivo

Various metal based nanoparticles such as Zn, Co and Cu are well known to have an anticancer effect. In targeting these nanoparticles, it is a great challenge to minimize the toxicity to normal cells. Folate receptors are expressed in a variety of cancer cells. Folic acid mediated targeting is a well accepted technique for cancer therapeutics. The purpose of this study is to explore the effect of novel copper carbonate (CuCO3) nanoparticles and their targeted delivery to cancer cells in vitro and in vivo. We synthesized the CuCO3 nanoparticles by a precipitation method, and they were characterized using various biophysical techniques. These CuCO3 nanoparticles (18–20 nm) induced DNA damage and disrupted the mitochondrial membrane, and finally cell death was mediated by apoptosis. Additionally, folic acid was conjugated to the CuCO3 nanoparticles, to deliver them specifically to cancer cells. To study the efficacy of the targeting, folate receptor knockdown HeLa cells were developed by sh-RNA and it was also further tested on a mouse model. These folic acid conjugated CuCO3 nanoparticles can be an effective therapeutic agent for folate receptor expressing cancer cells, and can therefore minimize the toxicity to normal cells.