Indium(III) complexes with lapachol: cytotoxic effects against human breast tumor cells and interactions with DNA.

Lapachol (2-hydroxy-3-(3-methylbut-2-en-1-yl)naphthalene-1,4-dione) is a 1,4-naphthoquinone-derived natural product that presents numerous bioactivities and was shown to have cytotoxic effects against several human tumor cells. Indium(III) complexes with a variety of ligands also exhibit antineoplastic activity. Indium(III) complexes [In(lap)Cl2].4H2O (1), [In(lap)2Cl(Et3N)] (2), [In(lap)3]·2H2O (3) [In(lap)(bipy)Cl2] bipy = 2,2'-bipyridine (4) and [In(lap)(phen)Cl2] phen = 1,10-phenanthroline (5) were obtained with 2-hydroxy-3-(3-methylbut-2-en-1-yl)naphthalene-1,4-dione (lapachol). Crystal structure determinations for (4) and (5) revealed that the indium(III) center is coordinated to two O atoms from lapachol, two N atoms from 1,10-phenanthroline or 2,2'-bipyridine, and two chloride anions, in a distorted octahedral geometry. Although both complexes (4) and (5) interacted with CT-DNA in vitro by an intercalative mode, only 5 exhibited cytotoxicity against MCF-7 and MDA-MB breast tumor cells. 1,10-phenanthroline and complex (5) presented cytotoxic effects against MCF-7 and MDA-MB cells, with complex (5) being threefold more active than 1,10-phenanthroline on MCF-7 cells. In addition, complex (5) significantly reduced the formation of MDA-MB-231 colonies in a clonogenicity assay. The foregoing results suggest that further studies on the cytotoxic effects and cellular targets of complex (5) are of utmost relevance.

Shell-Free Copper Indium Sulfide Quantum Dots Induce Toxicity in Vitro and in Vivo.

Semiconductor quantum dots (QDs) are attractive fluorescent contrast agents for in vivo imaging due to their superior photophysical properties, but traditional QDs comprise toxic materials such as cadmium or lead. Copper indium sulfide (CuInS2, CIS) QDs have been posited as a nontoxic and potentially clinically translatable alternative; however, previous in vivo studies utilized particles with a passivating zinc sulfide (ZnS) shell, limiting direct evidence of the biocompatibility of the underlying CIS. For the first time, we assess the biodistribution and toxicity of unshelled CIS and partially zinc-alloyed CISZ QDs in a murine model. We show that bare CIS QDs breakdown quickly, inducing significant toxicity as seen in organ weight, blood chemistry, and histology. CISZ demonstrates significant, but lower, toxicity compared to bare CIS, while our measurements of core/shell CIS/ZnS are consistent with literature reports of general biocompatibility. In vitro cytotoxicity is dose-dependent on the amount of metal released due to particle degradation, linking degradation to toxicity. These results challenge the assumption that removing heavy metals necessarily reduces toxicity: indeed, we find comparable in vitro cytotoxicity between CIS and CdSe QDs, while CIS caused severe toxicity in vivo compared to CdSe. In addition to highlighting the complexity of nanotoxicity and the differences between the in vitro and in vivo outcomes, these unexpected results serve as a reminder of the importance of assessing the biocompatibility of core QDs absent the protective ZnS shell when making specific claims of compositional biocompatibility.

The synthesis and investigation of photochemical, photophysical and biological properties of new lutetium, indium, and zinc phthalocyanines substituted with PEGME-2000 blocks.

Zinc(II) (5), indium(III) (6), and lutetium(III) (7) phthalocyanines (Pcs) peripherally substituted with poly (ethylene glycol) (PEG) monomethyl ether 2000 (PEGME-2000) blocks were synthesized via Sonogashira coupling reaction with high yields and their photophysical, photochemical and photobiological properties were investigated. We elucidated the interactions of these compounds with calf thymus DNA and bovine serum albumin (BSA), and determined K(DNA) and K(BSA) binding constants at degrees of 105 and 106, respectively. Singlet oxygen quantum yields were found (Ф∆ = 0.44, 0.54, and 0.68 for 5, 6, and 7, respectively). Thermodynamic parameters, as well as thermal denaturation profile of double-stranded CT-DNA were examined to determine the type of binding mode. According to our experimental data, we report that PEGME-2000 favors the formation of binary complex between DNA, and phthalocyanine complexes. Therein, thermodynamic data suggest that this binding mode is indeed spontaneous under reported conditions, and rather non-specific. Additionally, Pcs 5, 6, and 7 substituted with PEGME-2000 blocks showed antimicrobial activity against Gram-positive and Gram-negative bacteria, as well as fungi (yeast), and Pc 5 had the highest antimicrobial activity among them, as revealed by disc diffusion assay results. In short, our results suggest that these compounds could be used for photodynamic therapy, they have both antibacterial and antifungal activity, and the binding ability of new phthalocyanines 5, 6, and 7 with BSA paves the way for their utilization as drug vehicle in blood plasma.

Near-Infrared-Light-Triggered Antimicrobial Indium Phosphide Quantum Dots.

The emergence of multidrug-resistant (MDR) pathogens represents one of the most urgent global public health crises. Light-activated quantum dots (QDs) are alternative antimicrobials, with efficient transport, low cost, and therapeutic efficacy, and they can act as antibiotic potentiators, with a mechanism of action orthogonal to small-molecule drugs. Furthermore, light-activation enhances control over the spatiotemporal release and dose of the therapeutic superoxide radicals from QDs. However, the limited deep-tissue penetration of visible light needed for QD activation, and concern over trace heavy metals, have prevented further translation. Herein, we report two indium phosphide (InP) QDs that operate in the near-infrared and deep-red light window, enabling deeper tissue penetration. These heavy-metal-free QDs eliminate MDR pathogenic bacteria, while remaining non-toxic to host human cells. This work provides a pathway for advancing QD nanotherapeutics to combat MDR superbugs.

Solution-Processable Two-Dimensional In2 Se3 Nanosheets as Efficient Photothermal Agents for Elimination of Bacteria.

Two-dimensional (2D) nanoflakes represent an appealing class of materials for optoelectronics applications due to their unique layered structures and excellent electronic properties. However, the lack of easy-to-manipulate and effective methods for large-scale production of these 2D materials limits their potential for applications. Also, few efforts have been made to explore their applications in biological fields. This work reports the preparation of large quantities of 2D In2 Se3 nanosheets through a solvent exfoliation technique. Transmission electron microscopy and atomic force microscopy results show that the In2 Se3 nanosheets are obtained with lateral sizes of tens of nanometers to hundreds of nanometers and thickness of 2-17 layers. Raman features coupled with the X-ray diffractometry results unequivocally confirm the as-prepared In2 Se3 nanosheets to be α phase. Moreover, these α-In2 Se3 nanosheets exhibit an excellent near-infrared (NIR) photothermal performance under an 808 nm laser irradiation. NIR photo-excitation of the α-In2 Se3 nanosheets in the presence of bacteria leads to a significant antibacterial effect, suggesting that these nanosheets have great potential to be photothermal antibacterial agents. Our work on α-In2 Se3 nanosheets presents an available method for exfoliating 2D layered materials, and highlights the potential application in chemical and biological fields of α-In2 Se3 nanosheets.

Gram-Scale Synthesis of Hydrophilic PEI-Coated AgInS2 Quantum Dots and Its Application in Hydrogen Peroxide/Glucose Detection and Cell Imaging.

Assisted with polyethylenimine, 4.0 L of water-soluble AgInS2 quantum dots (AIS QDs) were successfully synthesized in an electric pressure cooker. As-prepared QDs exhibit yellow emission with a photoluminescence (PL) quantum yield up to 32%. The QDs also show excellent water/buffer stability. The highly luminescent AIS QDs are used to explore their dual-functional behavior: detection of hydrogen peroxide (H2O2)/glucose and cell imaging. The amino-functionalized AIS QDs show high sensitivity and specificity for H2O2 and glucose with detection limits of 0.42 and 0.90 µM, respectively. A linear correlation was established between PL intensity and concentration of H2O2 in the ranges of 0.5-10 µM and 10-300 µM, while the linear ranges were 1-10 µM and 10-1000 µM for detection of glucose. The AIS QDs reveal negligible cytotoxicity on HeLa cells. Furthermore, the luminescence of AIS QDs gives the function of optical imaging.

A Case of Focal Bone Marrow Reconversion Mimicking Bone Metastasis: The Value of 111Indium Chloride.

We present a case of a 66-year-old man with esophageal carcinoma. 18Fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) for evaluating distant metastasis and staging revealed 18F-FDG uptake in the third lumbar vertebra and other vertebrae. Magnetic resonance imaging could not differentiate bone metastases from benign bone lesions. We considered the possibility of bone marrow reconversion. 111Indium chloride (111In-Cl3) scintigraphy with single-photon emission computed tomography/computed tomography (SPECT/CT) revealed erythroid bone marrow components in the bone lesions. The diagnosis of bone marrow reconversion was pathologically confirmed by a bone biopsy of the third lumbar vertebra. The patient underwent esophagectomy and has remained disease-free in the 2 years since. To the best of our knowledge, this is the first report to describe the usefulness of 111In-Cl3 with SPECT/CT for the diagnosis of bone marrow reconversion.

Radiolabeled new somatostatin analogs conjugated to DOMA chelator used as targeted tumor imaging agent: synthesis and radiobiological evaluation.

Several receptor-specific radiopeptides have been developed and effective in the diagnosis of malignant diseases. Among them, somatostatin receptor (SSTR) scintigraphy with (111)In-DTPA-octreotide has become a tumor diagnostic radiopharmaceutical in nuclear medicine. However, it suffers some drawbacks concerning the imaging properties and elevated radiation burden of (111)In. Here, we report the synthesis of radiolabeled two new octapeptides with improved uptake in SSTR2-positive tumors in comparison with (99m)Tc-HYNIC-Tyr(3)-octreotide (HYNIC-TOC). Octapeptides were synthesized in high yield by Fmoc solid-phase synthesis and coupling the macrocyclic chelator DOMA(1,4,7-Tri-Boc-10-(carboxymethyl)-1,4,7,10-tetraazocyclododecane-1-yl-monoacetic acid) to these peptides for (99m)Tc labeling. New peptides DOMA-Asn(3)-octreotate(DOMA-AATE) and DOMA-Pro(3)-octreotate(DOMA-PATE) were purified, characterized by RP-HPLC, MALDI-mass, (1)H-NMR, (13)C-NMR. Labeling was performed by SnCl2 method to get products with excellent radiochemical purity (97 %). Radiopeptides were found to be substantially stable under physiological condition for 24 h. Internalization and receptor-binding studies were determined in somatostatin receptor-expressing C6-glioma cell line and rat brain cortex membrane and the results compared with HYNIC-TOC as standard. The IC50 values of (99m)Tc-DOMA-AATE(1.10 ± 0.48 nM) and (99m)Tc-DOMA-PATE(1.76 ± 0.06 nM) showed high affinity binding for SSTR2 receptor and they internalized rapidly in C6 cells. Biodistribution and imaging studies were performed in C6 tumor-bearing rat under gamma camera showing significant uptake in kidney, urine and C6 tumor. Radiopeptides exhibited fast blood clearance and rapid elimination through the urinary systems. However, (99m)Tc-DOMA-AATE exhibited the highest tumor to muscle and tumor to blood uptake ratios among three. These favorable characteristics validate (99m)Tc-DOMA-AATE as a more promising (99m)Tc-radiotracer than (99m)Tc-DOMA-PATE, (99m)Tc-HYNIC-TOC for SSTR2-positive tumor scintigraphy.

Indium-catalyzed oxidative cross-dehydrogenative coupling of chromenes with 1,3-dicarbonyls and aryl rings.

An effective indium-catalyzed oxidative cross-dehydrogenative coupling of electronically varied chromenes with 1,3-dicarbonyl compounds and aryl rings has been established. Both the C-H alkylation and arylation proceed smoothly at room temperature to afford diverse α-substituted chromene compounds in up to 91% yields. Besides these two types of C-H components, simple ketones like cyclohexanones also prove to be well tolerated.

Singlet oxygen production of Zn-Ag-In-S quantum dots for photodynamic treatment of cancer cells and bacteria.

Zn-Ag-In-S (ZAIS) quantum dots (QDs) were synthesized with various Ag-to-In ratios and used as novel photosensitizers for photodynamic therapy (PDT) on cancer cell inhibition and bacterial sterilization, and their structural, optical, and photodynamic properties were investigated. The alloyed QDs displayed a photoluminescence quantum yield of 72% with a long fluorescence lifetime of 5.3 µs when the Ag-to-In ratio was 1:3, suggesting a good opportunity as a dual functional platform for fluorescence imaging and PDT. The ZAIS QDs were then coated with amphiphilic brush copolymer poly(maleic anhydride-alt-1-octadecene) (PMAO) before application. The 1O2 quantum yield of the ZAIS/PMAO was measured to be 8%, which was higher than previously reported CdSe QDs and comparable to some organic photosensitizers. Moreover, the ZAIS QDs showed excellent stability in aqueous and biological media, unlike organic photosensitizers that tend to degrade over time. The in vitro PDT against human melanoma cell line (A2058) and Staphylococcus aureus shows about 30% inhibition rate upon 20 min light irradiation. Cell staining images clearly demonstrated that co-treatment with ZAIS QDs and light irradiation effectively killed A2058 cells, demonstrating the potential of ZAIS QDs as novel and versatile photosensitizers for PDT in cancer and bacterial treatment, and provides useful information for future designing of QD-based photosensitizers.

Evaluation of in vitro antileishmanial activity of curcumin and its derivatives "gallium curcumin, indium curcumin and diacethyle curcumin".

BACKGROUND AND OBJECTIVES: Leishmania parasites are intracellular haemoflagellates that infect macrophages of the skin and viscera to produce diseases in their vertebrates hosts. Antileishmania therapy is based on pentavalent antimony compounds which toxicity of these agents and the persistence of side effects are severe. Curcumin was identified to be responsible for most of the biological effects of turmeric. Turmeric plant extracts (curcumin and other derivatives) have anti-inflammatory, anti-arthritic, antioxidant, anti-microbial, antileishmanial, hepato protective, anti-cancer, anti-ulcer and anti diabetic activity. MATERIALS AND METHODS: Stock solutions of curcumin, indium curcumin, diacetylcurcumin and Gallium curcumin were made up in DMSO. From the each stock solution serial dilutions were made with phosphate buffered saline and 100 µl of each prepared concentration was added to each well of 96-well micro plate. All tests were performed in triplicate. Negative control only received RPMI-1640 medium with a parasite density of 106 parasites /ml and the positive control contained varying concentrations of standard antileishmania compound, Amphotericine B. MTT solution was prepared as 5 mg/ml in RPMI-1640 and 20 µl of this concentration was added to each well. Antileishmania effects of test agents and control were evaluated by using the MTT assay. RESULTS: Mean growth inhibition of triplicate for each concentration of test agents and control were measured. The IC50 values for curcumin, gallium curcumin [ga (CUR) 3], indium curcumin [in (CUR)3], Diacethyle Curcumin (DAC ) and Amphotericine B were 38 µg/ml, 32 µg/ml, 26 µg/ml, 52 µg/ml and 20 µg/ml respectively. Indium curcumin [in (CUR) 3] with IC50 values of 26 µg/ml was more effective than other three test agents against Leishmania. Mean growth inhibition of triplicate for Amphotericine B as control drug, was 20 µg/ml. CONCLUSIONS: Indium curcumin and Gallium curcumin complex showed more antileishmanial activity than curcumin and diacetylcurcumin and could be suitable candidates for further investigations.

Changes in Organ Weight, Sperm Quality and Testosterone Levels After Aluminum (Al) and Indium (In) Administration to Wistar Rats.

BACKGROUND: Aluminum and indium are widely used in industrial manufacturing, in pharmaceutical products, in medical treatments, and in food packaging, so they could reach organisms by different way. In order to clarify whether these elements are dangerous, we already demonstrated the ultrastructural modifications observed in the testicles, the epididymides, and the seminal vesicles of rat. Their pro-oxidative effect was also confirmed concomitantly to a decrease in anti-oxidant defenses in the blood, the testicles, and the liver. Thus, it seemed very logic to evaluate damages in the reproductive organs, especially on the exocrine and endocrine functions of the testicles. METHODS: Aluminum and indium were intraperitoneally administered to male Wistar rats. Sperm solution was obtained from cauda epididymides. Motility, viability, density, and malformation of spermatozoa solution were assessed. Serum total unconjugated testosterone concentrations were measured using RIA technique. RESULTS: Our results showed a decrease in weight of the testicles, epididymides, and seminal vesicles of indium-treated rats and an increase in the weight of their kidneys. A decrease in motility, viability, and density of epididymides stored sperm as well as generation of many spermatozoa malformations was also observed especially in indium-treated rats. Testosterone levels were increased in indium but were enhanced in aluminum group. This confirmed our previous studies showing that aluminum and indium are toxic for the testicular tissues. This could be explained by the generation of reactive oxygen species (ROS) affecting strongly the exocrine and the endocrine functions of the testicles. CONCLUSION: Aluminum and indium are disturbing elements for the exocrine and endocrine functions of rat testicles.

Gallium and indium complexes with isoniazid-derived ligands: Interaction with biomolecules and biological activity against cancer cells and Mycobacterium tuberculosis.

Gallium and indium octahedral complexes with isoniazid derivative ligands were successfully prepared. The ligands, isonicotinoyl benzoylacetone (H2L1) and 4-chlorobenzoylacetone isonicotinoyl hydrazone (H2L2), and their respective coordination compounds with gallium and indium [GaL1(HL1)] (GaL1), [GaL2(HL2)] (GaL2), [InL1(HL1)] (InL1) and [InL2(HL2)] (InL2) were investigated by NMR, ESI-MS, UV-Vis, IR, single-crystal X-ray diffraction and elemental analysis. In vitro interaction studies with human serum albumin (HSA) evidenced a moderate affinity of all complexes with HSA through spontaneous hydrophobic interactions. The greatest suppression of HSA fluorescence was caused by GaL2 and InL2, which was associated to the higher lipophilicity of H2L2. In vitro interaction studies with CT-DNA indicated weak interactions of the biomolecule with all complexes. Cytotoxicity assays with MCF-7 (breast carcinoma), PC-3 (prostate carcinoma) and RWPE-1 (healthy human prostate epithelial) cell lines showed that complexes with H2L2 are more active and selective against MCF-7, with the greatest cytotoxicity observed for InL2 (IC50 = 10.34 ± 1.69 µM). H2L1 and H2L2 were labelled with gallium-67, and it was verified that 67GaL2 has a greater lipophilicity than 67GaL1, as well as higher stability in human serum or in the presence of apo-transferrin. Cellular uptake assays with 67GaL1 and 67GaL2 evidenced that the H2L2-containing radiocomplex has a higher accumulation in MCF-7 and PC-3 cells than the non-halogenated congener 67GaL1. The anti-Mycobacterium tuberculosis assays revealed that both ligands and metal complexes are potent growth inhibitors, with MIC90 (µg mL-1) values observed from 0.419 ± 0.05 to 1.378 ± 0.21.

Visible light-responsive core-shell structured In2O3@CaIn2O4 photocatalyst with superior bactericidal properties and biocompatibility.

Antibacterial activity of photocatalytic substrates is primarily induced by ultraviolet light irradiation. Visible light-responsive photocatalysts were recently discovered, offering greater opportunity to use photocatalysts as disinfectants in our living environment. The development of antibacterial photocatalysts, however, has mainly focused on titanium oxide (TiO(2))-related materials with antibacterial properties not comparable with conventional chemical disinfectants. This study demonstrated that a core-shell structured In(2)O(3)@CaIn(2)O(4) substrate has superior visible light-induced bactericidal properties, as compared with several commercially available and laboratory-prepared visible light-responsive photocatalysts. The high performance is enhanced by more easily photoexcited electron transfer between the interfaces of In(2)O(3) and CaIn(2)O(4) to minimize the electron-hole recombination during photocatalysis. Additionally, when compared with TiO(2)-based photocatalysts, In(2)O(3)@CaIn(2)O(4) treatments did not induce significant cell death and tissue damage, implying a superior biocompatibility. These findings suggest that In(2)O(3)@CaIn(2)O(4) may have potential application in the development of a safer and highly bactericidal photocatalyst. FROM THE CLINICAL EDITOR: A photocatalytic susbstrate is described that functions in visible light, possesses bactericidal properties and better biocompatibility than the standard TiO(2) based methods.

Developing a Novel Indium(III) Agent Based on Human Serum Albumin Nanoparticles: Integrating Bioimaging and Therapy.

To effectively integrate diagnosis and therapy for tumors, we proposed to develop an indium (In) agent based on the unique property of human serum albumin (HSA) nanoparticles (NPs). A novel In(III) quinoline-2-formaldehyde thiosemicarbazone compound (C5) was optimized with remarkable cytotoxicity and fluorescence to cancer cells in vitro. An HSA-C5 complex NP delivery system was then successfully constructed. Importantly, the HSA-C5 complex NPs have stronger bioimaging and therapeutic efficiency relative to C5 alone in vivo. Besides, the results of gene chip analysis revealed that C5/HSA-C5 complex NPs act on cancer cells through multiple mechanisms: inducing autophagy, apoptosis, and inhibiting the PI3K-Akt signaling pathway.

Developing a Novel Indium(III) Agent Based on Liposomes to Overcome Cisplatin-Induced Resistance in Breast Cancer by Multitargeting the Tumor Microenvironment Components.

To overcome the resistance of cancer cells to platinum-based drugs and effectively suppress tumor growth, we developed a novel indium (In) agent based on liposomes (Lips). Thus, we not only obtained an In(III) thiosemicarbazone agent (5b) with remarkable cytotoxicity by optimizing a series of In(III) thiosemicarbazone agents (1b-5b) but also successfully constructed a novel 5b-loaded Lip (5b-Lip) delivery system. Importantly, in vitro and in vivo results revealed that 5b/5b-Lip overcame the tumor cell resistance and effectively inhibited MCF-7/DDP tumor growth. In addition, Lips improved the intracellular accumulation of 5b. We also confirmed the mechanism by which 5b/5b-Lip overcomes breast cancer cell resistance. 5b/5b-Lip cannot act against DNA in cancer cells but attacks the two cell components in the tumor microenvironment, namely, by inducing apoptosis and lethal autophagy of cancer cells and resetting tumor-promoting M2 macrophages to the tumor-killing M1 phenotype.

Superior antibacterial activity of gallium based liquid metals due to Ga3+ induced intracellular ROS generation.

Gallium-based liquid metals have increasing applications in a wide variety of emerging areas and they are involved more in frontier studies, the energy industry and additive manufacturing production, and even in daily life. When exposed to open air, large amounts of microorganisms may interact with liquid metals. However, the research of the relationship between pure gallium-based liquid metals and bacterial cells is still limited. In this study, the antibacterial properties of eutectic gallium-indium (EGaIn) alloys were tested against the typical Gram-negative bacteria-Escherichia coli and the Gram-positive bacteria-Staphylococcus aureus and the experimental results displayed that the antibacterial rates reached 100%. We also explored the mechanism of the anti-bacterial properties of EGaIn alloys by measuring the surface composition of the EGaIn film and the concentration of dissolved metal ions. The morphology of the bacterial cells showed that the cell growth and division were influenced by exposure to EGaIn. We also found that the synergistic antibacterial effect came along with the production of reactive oxygen species (ROS). Moreover, the EGaIn film showed enhanced antibacterial activity compared to gallium nitrate at the same initial ion concentration in the solution. This study shows the enormous potential of the anti-bacterial effect of liquid metals.

Acylated glycosides of hydroxy fatty acid methyl esters generated from the crude resin glycoside (pharbitin) of seeds of Pharbitis nil by treatment with indium(III) chloride in methanol.

Treatment of the crude ether-insoluble resin glycoside (convolvulin) from seeds of Pharbitis nil (Pharbitis Semen), called pharbitin, with indium(III) chloride in methanol provided seven oligoglycosides of hydroxy fatty acid methyl esters partially acylated by 2-methyl-3-hydroxybutyric (nilic) and 2S-methylbutyric acids. Their structures were elucidated on the basis of NMR and MS data and chemical conversions.

Strongly emitting and long-lived silver indium sulfide quantum dots for bioimaging: Insight into co-ligand effect on enhanced photoluminescence.

Nanoscale ternary chalcogenides have attracted increasing research interest due to their merits of tunable properties and diverse applications in energy and biomedical fields. In this article, silver indium sulfide quantum dots supported by glutathione and polyethyleneimine as dual-ligands have been synthesized through an environmentally friendly and reproducible aqueous method. An emission quantum yield up to 37.2% has been achieved by glutathione as co-ligand bearing electron-rich groups, much higher than that of polyethyleneimine coated quantum dots (4.97%). Both spectroscopic and structural characterizations demonstrate that the photoluminescence enhancement is attributed to change of surface properties by glutathione as co-ligand. Dynamic light scattering (DLS) results and thermogravimetric analysis (TGA) reveal that glutathione covers the QDs with a higher density on the nanocrystal surface than other co-ligands. Therefore, it can effectively passivate the surface trap centers, thus decreasing the non-radiative emission. Moreover, the resultant silver indium sulfide quantum dots present surprisingly long lifetime of 3.69 µs, excellent fluorescent stability and low cytotoxicity, which enables them to be ideal candidate for real-time bioimaging.

Nitrative DNA damage in lung epithelial cells exposed to indium nanoparticles and indium ions.

Indium compounds have been widely used in manufacturing displays of mobile phones, computers and televisions. However, inhalation exposure to indium compounds causes interstitial pneumonia in exposed workers and lung cancer in experimental animals. 8-Nitroguanine (8-nitroG) is a mutagenic DNA lesion formed under inflammatory conditions and may participate in indium-induced carcinogenesis. In this study, we examined 8-nitroG formation in A549 cultured human lung epithelial cells treated with indium compounds, including nanoparticles of indium oxide (In2O3) and indium-tin oxide (ITO), and indium chloride (InCl3). We performed fluorescent immunocytochemistry to examine 8-nitroG formation in indium-exposed A549 cells. All indium compounds significantly increased 8-nitroG formation in A549 cells at 5 ng/ml after 4 h incubation. 8-NitroG formation was largely reduced by 1400 W, methyl-ß-cyclodextrin (MBCD) and monodansylcadaverine (MDC), suggesting the involvement of nitric oxide synthase and endocytosis. 8-NitroG formation in A549 cells was also largely suppressed by small interfering RNA (siRNA) for high-mobility group box-1 (HMGB1), receptor for advanced glycation and end products (AGER, RAGE) and Toll-like receptor 9 (TLR9). These results suggest that indium compounds induce inflammation-mediated DNA damage in lung epithelial cells via the HMGB1-RAGE-TLR9 pathway. This mechanism may contribute to indium-induced genotoxicity in the respiratory system.