Fabrication of ZnO Nanoparticle-Based FET Device for Label-Free Bacteria Detection.

This paper reports fabrication and characterization of ZnO nanoparticle based Field Effect Transistor (FET) device and its application for simple, rapid and label-free bacteria detection. [Formula: see text] FET devices were fabricated by standard UV lithography technique on Si wafers. The fabricated devices consisted of ZnO nanoparticles as channel material. Characterization of such devices resulted in threshold voltage of -2 V and trans-conductance of [Formula: see text]. The interaction between ZnO nanoparticles and bacteria sample has been exploited in this study to utilize ZnO nanoparticle based FET device to successfully differentiate between gram positive and gram-negative bacteria. Gram negative bacteria sample resulted in higher output characteristics compared to that obtained with gram positive bacteria sample. This study reports sensitivity and Limit of Detection (LOD) of 9.48 nA/CFU/mL and 776 CFU/mL respectively for gram negative bacteria and 6.96 nA/CFU/mL and 665 CFU/mL for gram positive bacteria respectively.

Integration of a Nonsteroidal Anti-Inflammatory Drug with Luminescent Copper for in Vivo Cancer Therapy in a Mouse Model.

A facile, process of fabrication of a luminescent bovine serum albumin-copper nanocluster (BSA-CuNC) customized ibuprofen nanodrug (BSA-CuNC-Ibf), encapsulating the ibuprofen was developed. Ibuprofen, which is commonly used to treat inflammation, was utilized here as a model drug. The formation of BSA-CuNC initiated by encapsulation of the Cu ions within the protein moiety followed by gradual reduction of the Cu ions by certain amino acid residues like tyrosine and tryptophan at alkaline pH resulted in the formation of BSA-CuNC within the protein template. Heat treatment and lowering the pH fitted the ibuprofen in the center by hydrogen bonding, hydrophobic and electrostatic interactions, and resulted in the formation of nanoparticles. The nanodrug (BSA-CuNC-Ibf) thus formed was characterized by transmission electron microscopy (TEM), dynamic and static light scattering (DLS), and zeta potential. The spherical shaped nanodrug has a hydrodynamic diameter of about 100.4 ± 28.9 nm. The encapsulation efficiency was found to be 94% which corresponds to 1880 µg/mL of ibuprofen in the BSA-CuNC-Ibf nanodrug. The as synthesized BSA-CuNC-Ibf exhibited cytotoxicity on both human cervical cancer cells (HeLa) and human lung cancer cells (A549). The present nanodrug when explored for its tumor preventive role on Daltons lymphoma ascites (DLA) bearing Swiss albino mice, exemplified sizable inhibition of tumor growth by reactive oxygen species mediated apoptosis and by modulating prostaglandin (PGE2) levels. It also inhibited metastasis of the cancer cells, thus enhancing the life expectancy of the mice.

Role of surface charge in enhancing antibacterial activity of fluorescent carbon dots.

Herein, different surface charged carbon dots (Cdots) were synthesized by using diethylene glycol as a carbon source with various amine containing surface passivating agents. The synthesis method is very simple and fast microwave oven-based, that results in almost similar sized positive, negative and uncharged fluorescent Cdots which has been confirmed by zeta potential analysis in our case. The formation of Cdots was confirmed by characterization using fluorescence spectroscopy, transmission electron microscopy, XRD, FT-IR, and XPS spectroscopy. To find out relative bactericidal activity of these Cdots, green fluorescence protein expressing recombinant E. coli bacteria were taken as a model system. Time-dependent bacterial growth and FACS study demonstrated that both uncharged Cdots and positively charged Cdots were showing better bactericidal activity as compared to negative charged Cdots. The Cdots caused elevation of reactive oxygen species level, which is possibly leading to bacterial cell death.

Visible Light Excitation-Induced Luminescence from Gold Nanoclusters Following Surface Ligand Complexation with Zn2+ for Daylight Sensing and Cellular Imaging.

Herein, we report a complexation reaction-mediated extended aggregation of gold nanoclusters exhibiting luminescence under visible light excitation. The complexation reaction between the carboxylate groups of mercaptopropionic acid and zinc ions induced the aggregation of gold nanoclusters, which featured bright green luminescence upon excitation with visible light of wavelength 450 nm and beyond. This luminescence of aggregated Au NCs, easily discernible with bare eyes (under broad daylight excitation), was used as a probe for luminescence-based detection of molecules based on the p Ka values of the latter. This aspect has been an unfilled dream of scientists pursuing research on the development of nanoscale sensors, as luminescence-based detection techniques offer a greater degree of accuracy and sensitivity compared to absorption-based methods, and was thus far an unexploited/untapped area by nanoscale materials. Moreover, facile imaging of mammalian cells was achieved using these aggregated clusters upon excitation with visible light. This study demonstrates the utility of luminescent nanoclusters, akin to organic dyes, as materials active under visible light excitation. Thus, the complexation reaction-based tailoring of the optical properties of nanoclusters served as an effective tool in pushing the absorption maxima of the nanoclusters from an ultraviolet to visible range, enabling the luminescence of nanoclusters under broad daylight excitation. Hence, the work embodied herein offers a unique route to widen the application potential of metal nanoclusters as sensors and bioimaging agents operating under visible light excitation.

Crystallization-Induced Emission Enhancement of Nanoclusters and One-Step Conversion of "Nanoclusters to Nanoparticles" as the Basis for Intracellular Logic Operations.

Herein, we report the construction of intracellular logic operations using luminescent histidine stabilized gold nanoclusters (His Au NCs). The luminescence intensity of His Au NCs was found to be significantly enhanced following interaction with zinc ions, owing to "Crystallization induced emission enhancement". Further, the luminescence intensity of His Au NCs was found to be effectively quenched in presence of sulphide ions, owing to transformation of emissive His Au NCs to non-emissive gold nanoparticles. Thus, the collective and individual effects of zinc ions and sulphide ions causing significant variation in the luminescence intensity of His Au NCs, were used as input parameters for construction of intracellular logic operations such as Tri state buffer, "on-off" switch and INHIBIT gate within mammalian cells.

Solvent dependent synthesis of edge-controlled graphene quantum dots with high photoluminescence quantum yield and their application in confocal imaging of cancer cells.

We report on the synthesis of edge-controlled and highly fluorescent few-layer graphene quantum dots (GQDs) using different solvents and explore their application in the confocal imaging of cancer cells. TEM and AFM imaging analysis reveal that GQDs of sizes in the range 5-8 nm and few-layer (1-4) thickness were grown using DMF, DMSO, and water as solvents. Micro-Raman analysis reveals that GQDs grown with DMF possess primarily the armchair edges, while that grown with water contains primarily the zigzag edges. The nature of oxygen functional groups on the edge/in-plane sites of carbon atoms was elucidated through thermogravimetric and FTIR analyses. The GQDs containing high density of armchair edges and oxygen functional group defects exhibited high photoluminescence (PL) quantum yield (∼32%). The time-resolved PL measurements suggest the charge transfer from the GQDs to the surrounding dielectric medium. Further, we explore the high PL quantum yield of GQDs in bio-imaging of A-375 and HeLa cancer cells. The cell viability of GQDs on A-375 cells was found to be considerably higher than that of HeLa cells at a GQD concentration of 44.4 µg/mL, which is very significant. Our results indicate the GQD edge site dependent cell viability, for the first time. These results will be useful for the development of highly fluorescent GQDs with specific edge structure and their exploration in the field of bio-imaging, bio-sensing, and drug delivery applications.

Iron-Copper Bimetallic Nanocomposite Reinforced Dressing Materials for Infection Control and Healing of Diabetic Wound.

A multifunctional nanomaterial based wound healing matrix was fabricated by modified co-precipitation and chemical reduction method. The matrix was comprised of either a bimetallic Fe-Cu nanocomposite powder or a wound bed made up of absorbent cotton swab impregnated with bimetallic Fe-Cu nanocomposite. The detailed analytical studies of both dressing materials (powder and cotton bed) were carried out with transmission electron microscopy, X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray, and bright field microscopy. Both the nanocomposite powder and the nanocomposite impregnated cotton swab exhibited antimicrobial activity against Gram positive and Gram negative bacteria, including multidrug-resistant bacteria (such as methicillin-resistant Staphylococcus aureus) as well as against fungus isolated from different human biological samples (pus/tissue culture/urine). For real time applications, the in vivo wound healing ability of both dressing materials was also carried out in Wistar albino rats with infected diabetic wounds. These biocompatible and biodegradable dressing materials with broad-spectrum antimicrobial properties have exhibited more than 20 mm in diameter zone of microbial growth inhibition against several types of microbes. Remarkably, they have also been found to assist in healing of infected diabetic wounds and show a prospect in the management of other infectious wounds.

Polyethylene Glycol-Encapsulated Histone Deacetylase Inhibitor Drug-Composite Nanoparticles for Combination Therapy with Artesunate.

Combination drug therapy has become an effective clinical practice for cancer treatment because of low cytotoxicity by the synergistic effect of each medicine. Luminescent Au nanoclusters (Au NCs) were formulated into spherical polyethylene glycol (PEG)-Au NC-encapsulated drug-sodium butyrate (NaB) composite nanoparticles (PEG-Au NC-NaB-NPs) in the presence of PEG and NaB. Their effect on cancer cells was investigated using bio imaging, unravelling the mechanism of the endocytosis pathway and combination therapeutic interventions with a plant-based antimalarial drug artesunate (ART). PEG-Au NC-NaB-NPs showed bright red luminescence in the lysosomal compartment of the cells upon uptake predominantly through a caveolae-mediated pathway. Combination of PEG-Au NC-NaB-NPs with ART displayed enhanced therapeutic activity at a reduced dose compared to its individual doses and revealed heightened synergistic activity as identified from the combination index. The mechanism of synergism revealed elevated generation of reactive oxygen species with both NaB and ART, which disrupts mitochondrial membrane potential as evident from JC-1 staining. Remarkably, the histone deacetylase (HDAC) assay and terminal deoxynucleotidyl transferase dUTP nick end labeling assay enlightened the role of NaB and ART in HDAC inhibition and DNA fragmentation, respectively. Thus, induction of apoptosis with the synergistic effect of both NaB and ART with its meticulous mechanism makes it a promising tool for combinational cancer therapy. In vivo activity of the NPs was evaluated on Daltons lymphoma ascites bearing mice, which exhibited significant reduction of tumor volume and viable tumor cells with a prolonged life span.

In Situ Synthesis of Luminescent Au Nanoclusters on a Bacterial Template for Rapid Detection, Quantification, and Distinction of Kanamycin-Resistant Bacteria.

Herein, we introduce a new facile method of luminescent gold nanocluster (Au NC) synthesis on the surface of bacteria for detection, counting, and strain differentiation. The limit of detection was 740 ± 14 colony-forming unit (CFU)/mL for the Gram-negative and was 634 ± 16 CFU/mL for the Gram-positive bacteria. Brief treatment with lysozyme could differentiate the Gram strains based on their luminescence intensities. The current method could also detect bacterial contaminants from water sources and kanamycin-resistant strains rapidly. This quick synthesis of Au NCs on a bacterial template attributes an easy and rapid method for enumeration and detection of bacterial contaminants and kanamycin-resistant strains.

Probing Cancer Cells through Intracellular Aggregation-Induced Emission Kinetic Rate of Copper Nanoclusters.

pH-responsive luminescent copper nanoclusters (Cu NCs) with aggregation-induced emission (AIE) characteristics have been synthesized. Upon internalization into living cells, the NCs displayed a cellular pH environment-dependent luminescence change with orange-red emission at pHi 4.5, whereas bright green emission was observed over time at pHi 7.4, through their AIE attributes. Furthermore, the intracellular AIE kinetics of the NC probe was measured in MCF-7 cells and compared to that of HEK-293 cells. Intriguingly, the intracellular rate constant value derived for AIE kinetics in MCF-7 cells was found to be 3-fold higher than that in HEK-293 cell lines, whereas the value was 2-fold higher than that observed in aqueous medium. This provided a new platform to study different cell lines based on intracellular AIE in living cells, with additional potential for future applications in cellular imaging, diagnostics, and disease detection.

A New Bis(aquated) High Relaxivity Mn(II) Complex as an Alternative to Gd(III)-Based MRI Contrast Agent.

Disclosed here are a piperazine, a pyridine, and two carboxylate groups containing pentadentate ligand H2pmpa and its corresponding water-soluble Mn(II) complex (1). DFT-based structural optimization implied that the complex had pentagonal bipyramidal geometry where the axial positions were occupied by two water molecules, and the equatorial plane was constituted by the ligand ON3O donor set. Thus, a bis(aquated) disc-like Mn(II) complex has been synthesized. The complex showed higher stability compared with Mn(II)-EDTA complex [log KMnL = 14.29(3)] and showed a very high r1 relaxivity value of 5.88 mM-1 s-1 at 1.41 T, 25 °C, and pH = 7.4. The relaxivity value remained almost unaffected by the pH of the medium in the range of 6-10. Although the presence of 200 equiv of fluoride and bicarbonate anions did not affect the relaxivity value appreciably, an increase in the value was noticed in the presence of phosphate anion due to slow tumbling of the complex. Cell viability measurements, as well as phantom MR images using clinical MRI imager, consolidated the possible candidature of complex 1 as a positive contrast agent.

Crystalline assembly of gold nanoclusters for mitochondria targeted cancer theranostics.

Herein, we report the formation of a crystalline assembly of gold (Au) nanoclusters for cancer theranostics via active targeting of mitochondria. To the best of our knowledge, this is the first report of the target specific activity of an "assembly of gold nanoclusters". Au14 nanoclusters were stabilized with mercaptopropionic acid and l-tyrosine. The limited solubility of l-tyrosine in methanolic solution led to the formation of a polycrystalline assembly of Au nanoclusters via interactions between ligands (tyrosine) stabilizing the clusters. Further, complexation reaction between zinc ions and ligands stabilizing the Au nanoclusters led to the formation of a single crystalline assembly of gold nanoclusters. Transmission electron microscopic and selected area electron diffraction analyses revealed the formation of faceted crystals with a hexagonal arrangement of Au14 nanoclusters. A theoretical structure of the crystalline complex of Au nanoclusters and zinc ions has been proposed herein based on experimental observations and computational optimization. The crystalline assembly of Au nanoclusters, formed via ligand association as well as complexation reaction, exhibited mitochondria targeted anti-cancer activity - as verified by Mito Tracker staining experiments. However, the MTT assay, FACS analysis and JC-1 staining experiments revealed that the zinc mediated assembly of Au nanoclusters exhibited superior therapeutic action as compared to the methanol driven assembly of the clusters.

Bimetallic Fe-Cu Nanocomposites on Sand Particles for the Inactivation of Clinical Isolates and Point-of-Use Water Filtration.

Bimetallic Fe-Cu nanocomposites with an average size of 26.4 ± 4.7 nm were prepared on the surface of fine sand particles by modified coprecipitation and the chemical reduction method and were applied as an in vitro broad spectrum antimicrobial agent and recyclable hand-held water filter to sieve bacteria and metals. The size of the nanocomposites could be further reduced to 11.8 ± 1.6 nm when prepared after ball milling the sand particles, keeping the antimicrobial property intact. The results showed that the chemical nature and morphology of the nanocomposites had a great effect on both Gram-positive and Gram-negative bacteria with a minimum inhibitory concentration of 10.6 µg/mL and 13.8 µg/mL of copper, whereas the minimum bactericidal concentration was found to be 15.9 µg/mL and 21.2 µg/mL. The nanocomposites exhibited antimicrobial activity against multidrug-resistant bacteria as well as fungus isolated from different human biological samples like blood, urine, pus, and wound swabs. The nanocomposites were also capable of filtering a wide range bacteria like Acinetobacter baumannii, Escherichia coli, Salmonella typhi, Bacteroides fragilis, Salmonella paratyphi, Shigella dysenteriae, and Enterococcus faecalis, which are predominantly responsible for waterborne diseases. Further, the nanocomposites were used for the removal of hazardous metals like nickel, zinc, and lead. Leaching of copper and iron from the nanocomposites was within the permissible limit as per Bureau of Indian Standards (BIS) for Drinking Water (IS-10500-2012, second revision) as well as the International Standards for Drinking Water.

Transferrin-Copper Nanocluster-Doxorubicin Nanoparticles as Targeted Theranostic Cancer Nanodrug.

Transferrin (Tf)-templated luminescent blue copper nanoclusters (Tf-Cu NCs) are synthesized. They are further formulated into spherical Tf-Cu NC-doxorubicin nanoparticles (Tf-Cu NC-Dox NPs) based on electrostatic interaction with doxorubicin (Dox). The as-synthesized Tf-Cu NC-Dox NPs are explored for bioimaging and targeted drug delivery to delineate high therapeutic efficacy. Förster resonance energy transfer (FRET) within the Tf-Cu NC-Dox NPs exhibited striking red luminescence, wherein the blue luminescence of Tf-Cu NCs (donor) is quenched due to absorption by Dox (acceptor). Interestingly, blue luminescence of Tf-Cu NCs is restored in the cytoplasm of cancer cells upon internalization of the NPs through overexpressed transferrin receptor (TfR) present on the cell surface. Finally, gradual release of Dox from the NPs leads to the generation of its red luminescence inside the nucleus. The biocompatible Tf-Cu NC-Dox NPs displayed superior targeting efficiency on TfR overexpressed cells (HeLa and MCF-7) as compared to the cells expressing less TfR (HEK-293 and 3T3-L1). Combination index (CI) revealed synergistic activity of Tf-Cu NCs and Dox in Tf-Cu NC-Dox NPs. In vivo assessment of the NPs on TfR positive Daltons lymphoma ascites (DLA) bearing mice revealed significant inhibition of tumor growth rendering prolonged survival of the mice.

A highly stable l-alanine-based mono(aquated) Mn(ii) complex as a T1-weighted MRI contrast agent.

The synthesized lithium (S)-6,6'-(1-carboxyethylazanediyl)bis(methylene)dipicolinate (Li3cbda) is a new chiral, alanine-based ligand bearing two picolinate functionalities. The trianionic form of the ligand [(cbda)3-] constitutes a seven-coordinate, water-soluble, pentagonal bipyramidal Mn(ii) complex (1). The structural analysis reveals the presence of a water coordinating site in the complex. The complex is thermodynamically very stable, and the stability is not affected by the presence of physiological anions (HCO3-, PO43-, and F-). The pH of the medium exerts a small effect on the stability of the complex. The r1 relaxivity of 3.02 mM-1 s-1 is exhibited by the complex at 1.41 T, pH ∼7.4, and 25 °C. Phantom images obtained via a clinical MRI BRIVO MR355 system established concentration-dependent signal enhancement by the complex. The cytotoxicity test confirmed complex 1 as a biocompatible potential T1-weighted MRI contrast agent.

Functional characterization of recombinant human granulocyte colony stimulating factor (hGMCSF) immobilized onto silica nanoparticles.

OBJECTIVES: Granulocyte macrophage colony stimulating factor (GMCSF), an important therapeutic cytokine, was immobilized onto silica nanoparticles. Maintenance of structural integrity and biological performance in immobilized cytokine was assessed to augment its applicability in possible biomedical implications. RESULTS: Following its cloning and expression in E. coli, the recombinant human GMCSF (hGMCSF) was purified as a GST-tagged protein corresponding to a 42 kDa band on SDS-PAGE. The purified cytokine was immobilized onto biocompatible silica nanoparticles (~129.4 nm) by adsorption and the binding was confirmed by dynamic light scattering and infrared spectroscopy. Maximum binding of hGMCSF was at 6.4 µg mg(-1) silica nanoparticles. Efficient release of the cytokine from the nanoparticles with its structural integrity intact was deduced from circular dichroism spectroscopy. hGMCSF-immobilized silica nanoparticles efficiently increased the proliferation of RAW 264.7 macrophage cells with 50 % increase in proliferation at 600 ng hGMCSF µg(-1) silica nanoparticles. CONCLUSIONS: Silica nanoparticles successfully immobilized hGMCSF maintaining its structural integrity. The release of the immobilized cytokine from silica nanoparticles resulted in the increased proliferation of macrophages indicating the potential of the system in future applications.

Silver Nanocluster Embedded Composite Nanoparticles for Targeted Prodrug Delivery in Cancer Theranostics.

Cancer therapy with theranostic nanoparticles having the dual properties of concurrent delivery of therapeutics and its tracking offers a huge prospect to overcome the limitations of conventional therapy. Delivery of the nontoxic prodrug, which converts into the toxic drug due to cellular stimuli, offers a great deal of scope in cancer therapy. The paracetamol dimer (PD) generally considered as nontoxic is encapsulated with fluorescent silver nanocluster (Ag NC) embedded composite nanoparticles where it acts as a prodrug. This is possibly converted to a toxic metabolite due to elevated reactive oxygen species (ROS), leading to apoptosis mediated cell death. Conjugation of folic acid with these composite NPs offers the credibility of distinguishing between two different cancer cell lines such as HeLa, which overexpresses folic acid receptors, and A549, which down-regulates its expression, probed by the fluorescence intensity of Ag NCs. Importantly, Ag NCs along with PD synergistically induce prodrug mediated targeted cell death at a much reduced concentration of silver. Thus, theranostic nanocarriers have been developed offering the dual property of therapy and imaging based on the differential uptake.

Cu2+-embedded carbon nanoparticles as anticancer agents.

We report the synthesis of luminescent carbon nanoparticles (93 ± 50 nm) embedded with Cu2+. It was observed that at a relatively low concentration of Cu2+ (2.55 ppm), cervical cancer HeLa cells died due to apoptosis induced by the nanoparticles. Also, generation of reactive oxygen species in the cells, in the presence of the composite nanoparticles, has been attributed to their killing. The luminescence of the carbon nanoparticles was used for imaging of the cells.

Targeting Wnt Canonical Signaling by Recombinant sFRP1 Bound Luminescent Au-Nanocluster Embedded Nanoparticles in Cancer Theranostics.

Secreted frizzled-related protein 1 (SFRP1) is a natural blocker of the Wnt signaling pathway in normal adult cells but is epigenetically silenced in cancer cells leading to aberrant proliferation. In this study, we have reported novel composite nanoparticles fabricated with gold nanocluster embedded chitosan and alginate, bound to bacterially expressed human recombinant sFRP1. The Wnt pathway, which is upregulated in cancer, has been specifically targeted with the nanoparticles to achieve an antiproliferative effect on cancer cells, as evident from reduced levels of downstream molecules, namely, ß-catenin, cyclin D1, and survivin. The nanoparticles enabled sustained release of sFRP1 outside the cells, where it is functional. Moreover, remarkable luminescence properties of gold nanoclusters were exploited for binding, imaging, and tracking studies. Co-therapy of sFRP1-loaded nanoparticles with the drug cisplatin targeted two independent pathways to induce apoptosis, as documented by flow cytometry based assays. Overall, this nanosystem is promising for tracking, imaging, and targeting cancer signaling with therapeutic protein.