Amaresh Kumar Sahoo

Blue-emitting copper nanoclusters synthesized in the presence of lysozyme as candidates for cell labeling.

Highly fluorescent copper nanoclusters (Cu NCs) have been synthesized using single-step reduction of copper sulfate by hydrazine in the presence of lysozyme. The fluorescence quantum yield was measured to be as high as 18%. The emission was also found to be dependent on the excitation wavelength. Mass spectrometric analyses indicated the presence of species corresponding to Cu2 to Cu9. Transmission electron microscopic analyses indicated the formation of agglomerated particles of average diameter of 2.3 nm, which were constituted of smaller particles of average diameter of 0.96 nm. They were found to be stable between pH 4 and 10 and in addition having excellent chemical and photostability. The noncytotoxic NCs were used to successfully label cervical cancer HeLa cells.

Simultaneous RGB Emitting Au Nanoclusters in Chitosan Nanoparticles for Anticancer Gene Theranostics

Advanced theranostic materials hold promise for targeted delivery of drugs, with the ability to follow the transport as well as its consequences. This should, ideally, be possible with minimum invasive surgery and having no or minimum cytotoxicity of the materials. It requires development of newer materials whose physical properties would allow for easy probe, which could carry the therapeutic molecules, which will be stable under physiological conditions, and at the same time would be able to permeate barriers to the target. We report the development of a composite consisting of highly fluorescent Au nanoclusters and the biopolymer chitosan, which could easily be converted into nanoparticles and would form a stable polyplex with suicide gene for induction of apoptosis in cervical cancer cells. The simultaneous red, green, and blue fluorescence from the nanoclusters provided convenient optical imaging and flow cytometry probes, without having to use additional dyes. Moreover, the colloidal nanocluster-polymer composite could be converted into solid film and be stored with the retention of optical properties. The pH tunable optical properties in the medium were also intact in the films that quickly dissolved in water with retention of properties.

Bimetallic silver nanoparticle–gold nanocluster embedded composite nanoparticles for cancer theranostics

A bimetallic silver nanoparticle based gold nanocluster module has been developed for theranostic cellular application by a rapid and simple galvanic exchange method. The use of chitosan as a template has helped to convert the bimetallic system into composite nanoparticles, which can be easily delivered into cancer cells. The synthesized composite nanoparticles offer the advantage of combinatorial properties of the metals present in two different nanoscale levels enabling both killing and bioimaging of cancer cells. Detailed molecular events of cell death were illustrated for this combined module to decipher apoptotic mediated cell death.

Plasmid DNA linearization in the antibacterial action of a new fluorescent Ag nanoparticle–paracetamol dimer composite

Herein, we report the generation of a composite comprised of p-hydroxyacetanilide dimer and Ag nanoparticles (NPs) by reaction of AgNO(3) and p-hydroxyacetanilide. The formation of the composite was established by UV-vis, FTIR and NMR spectroscopy, transmission electron microscopy and X-ray diffraction along with substantiation by mass spectrometry. Interestingly, the composite exhibited an emission spectrum with a peak at 435 nm when excited by light of wavelength 320 nm. The composite showed superior antimicrobial activity with respect to its individual components against a wide range of Gram positive and Gram negative bacteria at relatively low concentrations of Ag NPs and at which there was no apparent cytotoxicity against mammalian cells. Our results suggest that the composite strongly interacted with the bacterial cell walls leading to cell bursting. Interestingly, enhancement in the reactive oxygen species (ROS) generation in bacteria was observed in the presence of the composite. It is proposed that the ROS generation led to oxidation of the dimer to N-acetyl-p-benzoquinone imine (NAPQI). The generated NAPQI acted as a DNA gyrase inhibitor causing cell death following linearization of DNA.

Hierarchical Logic Structures Based on Responsive Fluorescent Gold Nanoclusters

Logic with Gold Clusters. Gold nanoclusters can be used for the development of hierarchical logic structures. This is based on the reversible change in the fluorescence of the clusters at different pH of the medium, its temperature and metal ion concentration dependence.

Silver nanoparticle loaded PLGA composite nanoparticles for improving therapeutic efficacy of recombinant IFNγ by targeting the cell surface

The field of medical science has advanced significantly with the discoveries of new drugs and the development of sophisticated biomedical tools; still cancer therapy remains one of the major hurdles currently. Herein, we report a new approach, which exhibits complementary anti-cancer effects of recombinant IFNγ protein and silver nanoparticles (Ag NPs) when loaded together in PLGA composite NPs (GST IFNγ-Ag PLGA NPs). IFNγ acts as an antiviral and tumoricidal agent. To augment therapeutic efficacy, IFNγ was cloned, purified as GST tagged IFNγ recombinant protein, and immobilized on the composite NPs preloaded with Ag NPs. The NPs were characterized using UV-vis spectroscopy, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM) and dynamic light scattering (DLS) analysis. Finally, the composite NPs were delivered into two different human cancer cell types, HeLa (cervical cancer) and MCF-7 (breast cancer) cells. Our results demonstrated that the recombinant IFNγ could block the cell cycle at the G1 phase and its anticancer activity could be potentiated in the presence of Ag NPs. The interaction between the recombinant IFNγ with its cell surface receptors facilitated the delivery of the composite NPs, and thus the combination of the duos ultimately led to induction of apoptosis in the cancer cells.

Hydrogel nanocarrier encapsulated recombinant IκBα as a novel anticancer protein therapeutics

The NFκB overexpression triggers drug resistance in many types of cancer by up-regulating anti-apoptotic genes. IκBα, an endogenous protein and natural inhibitor of NFκB, blocks translocation of NFκB from cytoplasm to nucleus and thereby, sensitizes cancer cells to external stimuli. Herein, we have cloned a PCR amplified cDNA of IκBα, and expressed the recombinant GST tagged IκBα in Escherichia coli BL21 (DE3) cells. The recombinant GST-IκBα was purified by glutathione-agarose affinity chromatography and characterized by Western blot, MALDI-TOF, UV-Vis spectroscopy and circular dichroism spectroscopy. The GST-IκBα recombinant protein was encapsulated within polyvinyl alcohol (PVA)/polyvinyl pyrrolidone (PVP) hydrogel nanocarrier (NC) and then characterized by transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS) and zeta potential measurements. The pH-dependent protein release was performed in vitro to study the pH tunability of the hydrogel NCs. Furthermore, the therapeutic efficacy of GST-IκBα loaded hydrogel NCs was evaluated on HeLa (cervical carcinoma) cells by cytotoxicity assay and cell cycle analysis. TUNEL assay by flow cytometry confirmed apoptosis of HeLa cells. Administration of GST-IκBα by hydrogel NCs showed significant cell growth inhibition of drug resistant U87MG cells in combination with 5-FU. Our results essentially attributed the hydrogel NC-mediated administration of recombinant GST-IκBα as a novel recombinant protein therapeutic approach for cancer, which may further be regimented in combination therapy.

Plasmonic Signatures in the Composite Crystals of Gold Nanoparticles and p-Hydroxyacetanilide (Paracetamol)

A new type of inorganic nanoparticle-organic hybrid crystalline material consisting of gold nanoparticles (Au NPs) and p-hydroxyacetanilide (pHA) is reported. The composite crystals were on the order of several millimeters in dimensions. They could be grown from a solution of Au NPs and pHA at 35 °C. The optical properties of the crystals not only reflected the presence of Au NPs but also their degree of association inside the crystals. Single crystal X-ray diffraction data indicated that the crystal motifs were those of pHA. Transmission electron microscopic images indicated Au NPs being dispersed randomly in the crystal with increase in their density when crystallized in the presence of low concentration of pHA. FTIR measurements indicated attachment of -NH group to the NPs. Optical microscopic investigation revealed the presence of Au NP crystals, the color of which represented their density, being red at low concentration of NPs and purple at their high concentration.

Chemosensitization of IκBα-overexpressing glioblastoma towards anti-cancer agents

Burgeoning research on gene-directed therapeutics has significant translational scope to combat multidrug resistant glioblastoma when conventional anticancer drugs cease to work alone or in combination. In the present work, a novel strategy to sensitize drug resistant glioblastoma cells (U87MG) has been proposed by overexpressing the IκBα gene, which is a cellular inhibitor of NFκB signaling pathways. The IκBα overexpressing U87MG cell line (U87-IκBα) was established by the G418 selection of IκBα transfected U87MG cells. The expression of IκBα was studied by semi-quantitative RT PCR, real time PCR and Western blot analysis. The stable cells were found to be easily sensitized by the anticancer drug 5-fluorouracil (5-FU) and an unconventional therapeutic agent curcumin nanoparticles. Cell viability assays and flow cytometry-based cell cycle studies showed dose dependent differential effects of 5-FU on U87-IκBα and U87MG cells. The expression status of various cell cycle genes was examined by real time PCR analysis. Furthermore, water soluble curcumin nanoparticles (NPs) were synthesized in the presence of poly-L-lysine and BSA to sensitize U87-IκBα cells. Results demonstrated the augmentation of the therapeutic potential of 5-FU and curcumin nanoparticles on IκBα overexpressed cells. Thus, this simple strategy offers the scope of using combination modules as a potential cancer therapeutic.

Thumb Imprint Based Detection of Hyperbilirubinemia Using Luminescent Gold Nanoclusters

Early and easy detection of diseases, using point-of-care and inexpensive devices, not only provides option for early treatment but also reduces the risk of propagation. Herein we report the fabrication of a robust film based luminescence indicator of bilirubin, which can indicate hyperbilirubinemia through the thumb imprint of the patient. The UV-light induced luminescence intensity of the film, made out of chitosan stabilised gold (Au) nanoclusters, which was effectively quenched in the presence of Cu2+ ions, recovered in the presence of bilirubin from skin or blood serum. Moreover, the sensitivity of detection of bilirubin was tuneable with the amount of Cu2+ added, thereby facilitating the detection of the desired concentration range of bilirubin.