Enhanced antibacterial activity of cadmium telluride nanocrystals in combination with 940-nm laser diode on anaerobic bacteria P. gingivalis: an in vitro study.

Periodontal disease is one of the most common chronic diseases in the oral cavity that causes tooth loss. Root scaling and leveling cannot eliminate all periodontal pathogens, and the use of antibacterial agents or lasers can increase the efficiency of mechanical methods. The aim of this study was to evaluate and compare the antibacterial activity of cadmium telluride nanocrystals in combination with 940-nm laser diode. Cadmium telluride nanocrystals were prepared by a green route of synthesis in aqueous medium. The results of this study showed that cadmium telluride nanocrystals significantly inhibit the growth of P. gingivalis. The antibacterial property of this nanocrystal increases with increasing its concentration, laser diode 940-nm irradiation and with increasing the time. It was shown that the antibacterial activity of combination of 940-nm laser diode and cadmium telluride nanocrystals is greater than the effect of either alone and can have a similar effect with its long-term presence of microorganisms. This is very important because it is not possible to use these nanocrystals in the mouth and in the periodontal bag for a long time.

Highly Sensitive Fluorescent Probe for Detection of Paraquat Based on Nanocrystals.

Paraquat is one of the most toxic materials widely applied in agriculture in most countries. In the present study, a simple, innovative and inexpensive nano biosensor which is based on a thioglycolic acid (TGA) - CdTe@CdS core-shell nanocrystals (NCs) to detect paraquat, is suggested. The NCs based biosensor shows a linear working range of 10-100 nM, and limited detection of 3.5 nM. The proposed sensor that has been well used for the detection and determination of paraquat in natural water samples is collected from corn field and a canal located near to the corn field yielding recoveries as high as 98%. According to our findings, the developed biosensor shows reproducibility and high sensitivity to determine paraquat in natural water samples in which the amount of paraquat has low levels. The suggested method is efficiently applied to paraquat determination in the samples of natural water that are collected from a tap water and a canal located near to the cornfield.

Synthesis of Magnetic Ions-Doped QDs Synthesized Via a Facial Aqueous Solution Method for Optical/MR Dual-Modality Imaging Applications.

This research reports the preparation and examination of Cadmium Telluride (CdTe) Quantum Dots and doping CdTe QDs with Europium (Eu), Gadolinium (Gd), and Manganese (Mn) prepared in aqueous solution using TGA as a capping agent. Magnetic QDs (MQDs) are important agents for fluorescence (FL) /magnetic resonance (MR) dual-modal imaging due to their excellent optical and magnetic properties. Herein, the chemical bonds, structural, fluorescence, and magnetized properties of CdTe QDs and effect of Mn, Eu, and Gd ions doping on their properties were examined by X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HRTM), Energy-dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FTIR), photoluminescence spectroscopy (PL), Ultraviolet-visible spectroscopy (UV-Vis), and vibrating sample magnetometer measurements (VSM). Almost similar X-Ray patterns with the absence/presence of ions for all samples with cubic crystal structures were obtained which indicated that the introduction of ions into CdTe QDs could not alter the cubic primary structure of CdTe. Monodisperse size distributed with seemingly-spherical shapes, and also, the estimated mean diameters about 3 and less than 3 nm of QDs were obtained. The effect of X ions injection on the fluorescence and UV-Vis properties of the QDs were also investigated. Optical studies showed the decreases in bandgap as the heating time increases during synthesis while undergoing red-shift. The CdTe nanocrystals with high PL quantum yields were achieved in more than 6 h of heating. Also, investigations have shown the quenching of fluorescence by the existence of ions in the CdTe QDs. Then, all the ions doped QDs exhibited ferromagnetic behavior at room temperature by a vibrating sample magnetometer which confirmed the success of the presentation of ions into CdTe cubic crystal structure. They can have been employed as a suitable contrast agent successfully for biological applications such as FL/MR dual-modal imaging.

Cadmium telluride quantum dots induce apoptosis in human breast cancer cell lines.

INTRODUCTION: Semiconductor quantum dots (QDs), especially those containing cadmium, have undergone marked improvements and are now widely used nanomaterials in applicable biological fields. However, great concerns exist regarding their toxicity in biomedical applications. Because of the lack of sufficient data regarding the toxicity mechanism of QDs, this study aimed to evaluate the cytotoxicity of three types of QDs: CdTe QDs, high yield CdTe QDs, and CdTe/CdS core/shell QDs on two human breast cancer cell lines MDA-MB468 and MCF-7. METHODS: The breast cancer cells were treated with different concentrations of QDs, and cell viability was evaluated via MTT assay. Hoechst staining was applied for observation of morphological changes due to apoptosis. Apoptotic DNA fragmentation was visualized by the agarose gel electrophoresis assay. Flow cytometric annexin V/propidium iodide (PI) measurement was used for apoptosis detection. RESULTS: A significant decrease in cell viability was observed after QDs treatment ( p < 0.05). Apoptotic bodies and chromatin condensation was observed by Hoechst staining. DNA fragmentation assay demonstrated a DNA ladder profile in the exposed cells and also annexin V/PI flow cytometry confirmed apoptosis in a dose-dependent manner. CONCLUSION: Our results revealed that CdTe, high yield CdTe, and CdTe/CdS core/shell QDs induce apoptosis in breast cancer cell lines in a dose-dependent manner. This study would help realizing the underlying cytotoxicity mechanism, at least partly, of CdTe QDs and may provide information for the development of nanotoxicology and safe use of biological applications of QDs.

The phenotypic and genotypic antibiotic susceptibility of vaginal Lactobacillus with potential probiotic properties isolated from healthy women in northern Iran.

Background and Objectives: This study assesses the antibiotic susceptibility of vaginal Lactobacillus strains and provides data for determining the prevalence of certain antibiotic resistance genes in the new strains of lactobacilli serving as probiotics and selected from healthy women in northern Iran. Materials and Methods: One hundred premenopausal non-pregnant women in the reproductive age range of 22-50 years participated in this study. The potential probiotic vaginal lactobacilli used in the study included Lactobacillus crispatus (34.2%), Lactobacillus gasseri (26.3%), Lactobacillus johnsonii (10.5%), Lactobacillus acidophilus (15.7%) and Lactobacillus jensenii (13.1%). The phenotypic antibiotic susceptibility of the strains was determined by E test and DNA extraction and PCR were performed to examine the antibiotic resistance genes. Results: 38 potential probiotic vaginal lactobacilli were isolated. All the strains of lactobacilli were resistant to metronidazole and trimethoprim/sulfamethoxazole and all of the strains were susceptible to ampicillin and chloramphenicol antibiotics. The results showed that ermB, ermC, and ermA genes were observed in the strains of Lactobacillus acidophilus. Metronidazole resistance (nim) gene was also found in one strain of Lactobacillus crispatus and Lactobacillus johnsonii. The aminoglycoside resistance (aac6'-aph2″) gene was observed in 8% of the strains. Also, tetM, tetK and tetW genes were found in more than 80% of the Lactobacillus strains. Conclusion: The antimicrobial susceptibility of vaginal lactobacilli is an important criterion for establishing whether or not the organism is a probiotic. A high level of resistance to clinical antibiotics, such as metronidazole and aminoglycosides, was demonstrated. Antibiotic resistant genes also appeared widely in vaginal lactobacilli.

Radiolabeled florescent-magnetic graphene oxide nanosheets: probing the biodistribution of a potential PET-MRI hybrid imaging agent for detection of fibrosarcoma tumor.

PURPOSE: Radiolabeled graphene oxide (GO) nanosheets has been one of the most extensively studied nanoplatform for in vivo radioisotope delivery. Herein, we describe the functionalization of the surface of GO nanosheets with Fe3O4 magnetic nanoparticles, cysteine amino acid as an interface ligand, and cadmium telluride quantum dots. MATERIALS AND METHODS: To enable In vivo PET imaging, the GO@Fe3O4-cys-CdTe QDs were labeled with 68Ga to yield [68Ga] Ga-Go@ Fe3O4-Cys-CdTe QDs. Furthermore, serum stability tests were performed and the biological behavior of the nanocomposite was evaluated in rats bearing fibrosarcoma tumor. RESULTS: Liver, blood and tumor were the most accumulated sites at 1 h after the injection, and the radiolabeled nanocomposite as a PET/MRI imaging agent showed fast depletion from body and acceptable tumor uptake. CONCLUSION: Magnetic (Fe3O4) and fluorescent components (CdTe QDs) along with a positron-emitting radionuclide will help to design a multimodal imaging system (PET/MRI/OI) which will offer the advantages of combined imaging techniques and further possible used in localized radionuclide therapy. Overall, [68Ga] Ga-GO@Fe3O4-cys-CdTe QDs nanocomposite shows great promise as a radiolabeled imaging agent owing to high accumulation in tumor region.

Effects of concertation and size of aqueous QDs on the detection of ionizing radiation based on changes in optical properties.

Colloidal quantum dots (QDs) have recently been used in many applications. In particular, semiconductor and luminescent QDs are suitable candidate for use in optoelectronic devices and optical sensors. The optical properties of aqueous CdTe QDs with high efficiency photoluminescence (PL) make them good candidates for new dosimetry applications. Therefore, comprehensive studies are required of the effects of ionizing radiation on the optical properties of CdTe QDs. In the present study, we investigated the properties of aqueous CdTe QDs by a gamma 60Co source at different doses. For the first time, we determined the effects of the concentration and size of QDs, which are key factors in a gamma dosimeter. The results demonstrated the concentration-dependent photobleaching property of QDs, which grater changes in the optical properties occurred. The initial size of the QDs affected their optical properties, where red-shifting of PL peak position increased with smaller sizes. Analysis of the effect of gamma irradiation on the thin film QDs indicated that the PL intensity decrease as the dose increased. with increasing dose. X-ray diffraction analysis found no changes in the crystal structure. X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy indicated decomposition of the capping agent thioglycolic acid on CdTe QDs after gamma irradiation.

Caveolae-dependent endocytosis mediates the cellular uptake of CdTe quantum dots in ovarian cancer cell lines.

Background and purpose: Quantum dots (QDs) are semiconductor nanocrystals that are widely used in biology due to their good optical properties. QDs, especially cadmium-based QDs, play an important role in the diagnosis and treatment of cancer due to their intrinsic fluorescence. The aim of the present study was the evaluation of the cellular uptake mechanisms of CdTe QDs in ovarian cancer cell lines. Experimental approach: In this study, we used CdTe QDs coated with thioglycolic acid. The ovarian cancer cell lines SKOV3 and OVCAR3 were treated with different concentrations of QDs, triamterene, chlorpromazine, and nystatin, and cell viability was evaluated through the MTT test. To find the way of cellular uptake of CdTe QDs, we used the MTT test and interfering compounds in endocytic pathways. Intrinsic fluorescence and cellular internalization of CdTe QDs were assessed using flow cytometry and fluorescence microscopy imaging. Findings / Results: The viability of CdTe QDs-treated cells dose-dependently decreased in comparison to untreated cells. To evaluate the cellular uptake pathways of CdTe QDs, in most cases, a significant difference was observed when the cells were pretreated with nystatin. The results of flow cytometry showed the cellular uptake of CdTe QDs was dose- and time-dependent. Conclusion and implications: Nystatin had a measurable effect on the cellular uptake of CdTe QDs. This finding suggests that caveola-mediated endocytosis has a large portion on the internalization of CdTe QDs. According to the results of this study, CdTe QDs may have potential applications in cancer research and diagnosis.

Study of double-using ultrasonic effects on the structure of PbO nanorods fabricated by the sonochemical method.

In this study, lead oxide (PbO) nanostructures are fabricated by an ultrasound-assisted sonochemical method, and re-ultrasonic effects on them are investigated. In the synthesis process, lead nitrate powder is used as a precursor, and potassium hydroxide serves as a precipitation agent. The resulting samples are characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and Fourier transform-infrared spectroscopy (FT-IR). Re-ultrasound is also performed to terminate the growth of the PbO nanorods, stabilize them, and preserve their morphology. According to the XRD results, the re-ultrasonic effect did not change the crystal phases, and the tetragonal and orthorhombic crystal phases were preserved. The effect of the calcination time was investigated too; an increase in it led to a decrease in the irregular nanorods size but an increase in the crystallite size.

Influence of heavy nanocrystals on spermatozoa and fertility of mammals.

In recent years, quantum dots (QDs) have been widely used in upcoming nanotechnology-based solar cells, light-emitting diodes and even bioimaging, due to their tunable optical properties and excellent quantum yields. But, such nanostructures are currently constituted by heavy elements which can threat the human health and living environment. Hence, in this work, the in vivo effects of CdTe nanocrystals (NCs) (as one of the promising QDs) on spermatozoa of male mice and subsequently on fertility of female mice were investigated, for the first time. To do this, CdTe NCs were synthesized through an environment-friendly (aqueous-based solution) method. The sperm cells presented a high potential for uptake of the heavy QDs. Meantime, the NCs exhibited concentration-dependent adverse effects on morphology, viability, kinetic characteristics and DNA of the spermatozoa. At low concentration of 0.1µg/mL, the NCs showed a moderate toxicity (~25% reduction in viability and motility of the spermatozoa), while remarkable toxicities were observed at higher concentrations of 1.0-100µg/mL (~67% reduction in viability and motility for 100µg/mL). Furthermore, significant in vitro DNA fragmentation of the spermatozoa was observed at CdTe concentrations ≥10µg/mL. In vivo toxicity of the NCs was found lower than the in vitro toxicity. Nevertheless, the in vivo destructive effects of the NCs still caused ~34% reduction in viability as well as motility and ~5% damages in DNA of male mice spermatozoa. These resulted in ~26% decrease in fertility and gestation of female mice, along with an overall hormone secretion during the pregnancy, and ~39% reduction in viability of pups/pregnant females.