Showing 7 results for Quantum Dots
M. Gheraat , R. Sajedi , N. Jalilian , M. Shanesaz, M. Mirshahi ,
Volume 9, Issue 4 (12-2018)
Abstract
Aims: The use of semiconductor quantum dots (QD) nanoparticles with emission spectrum in the visible region as a marker in immunoassays provides the user with an opportunity to detect the desired agent without using advanced equipment. Accordingly, the aim of this study was to present a one-step conjugation method for antibodies with CdTe quantum dots, using activated dextran.
Materials and Methods: In this experimental study, CdTe nanoparticles were synthesized and the transmission electron microscope was used to study the morphology of the synthesized QD of CdTe and the size, concentration, and stability of the synthesized nanoparticles were evaluated. In order to stabilize the nanoparticles synthesized by BSA (Bovine Serum Albumin), they were coated and connected to antibodies with activated dextran. Immunosuppression tests were used to evaluate the conjugated antibodies.
Findings: Spot and spherical nature were completely evident in the morphology of nanoparticles. The difference in QD and dBSA-QD displacement from the agarose gel confirmed the formation of dBSA-QD and the same dilution spectrum from nanoparticles was obtained in the presence and absence of BSA. Connecting with dBSA, in addition to maintaining and improving the properties of the nanoparticle's diffusion led to the creation of diverse functional groups for the next steps of nanoparticle connection. The fluorescence emission of nanoparticles was higher in both coated with dBSA and conjugated with antibodies than free nanoparticles. By using antibodies connected to nanoparticles, the detection limit of 30ng for protein antigen was obtained as an eye.
Conclusion: In the conjugation process, in order to connect CdTe quantum dots to antibodies via dextran, by coating nanoparticles with a denatured BSA in addition to increasing the stability of nanoparticles, new functional groups are created on the surface of the nanoparticle.
S. Moasses Ghafary, M. Nikkhah, Sh. Hatamie, S. Hosseinkhani,
Volume 10, Issue 1 (3-2019)
Abstract
One of the main challenges in the treatment of genetic disorders, such as cancer, is of drug delivery systems and their inability to monitor and track delivered drug to the targeted site. Therefore, the design of novel with dual capabilities of nuclear drug delivery and tracking into a research priority for this field’s The aim of this study is to design based on both non-cytotoxic quantum dots and chimeric peptides, with dual tracking and delivering small genetic agents into the nucleus. The GQDs with green emission color were synthesized by Hummer’s and methods and characterized by UV-Vis, photoluminescence (PL), Raman spectroscopies, and scanning electron microscopy (SEM). conjugated with MPG-2H1 chimeric peptides through noncovalent interactions. Following conjugation step, the ζ-potential of the complex increased (From -38.6 to -11.1 in complex1, -9.6 in complex2 and -5.74 in complex3). The conjugation was confirmed by native acrylamide gel retardation assay. The of the GQDs was investigated by MTT assay and finally, was carried out. The results showed that MPG-2H1/ GQD complexes can enter cells; however, free-GQDs didn’t enter the cells significantly.
F. Hajipour, S. Asad, M.a. Amoozegar, Kh. Khajeh,
Volume 10, Issue 3 (9-2019)
Abstract
Quantum dots have received great attention for the past years as fluorescent markers for physical, chemical, and biological applications due to their unique size-dependent electrical and optical properties such as high extinction coefficient, broad absorption with narrow symmetric size-tunable fluorescent spectra, and strong resistance to photobleaching with significant luminescence quantum yield. In this study, at first the CdSe/ZnS quantum dots coated with oleylamine surface ligand were synthesized by high temperature injection method under vacuum conditions and stable nitrogen at 320°C. Then, in order to investigate the quenching effect of azo dyes, which is one of the most carcinogenic chemical colors used in various industries, on the emission of these nanoparticles, we used mercaptopropionic acid as a suitable hydrophilic ligand at the surface modification of quantum dots in the ligand exchange process as a proper aqueous phase transfer strategy. After confirming the proper synthesis of CdSe/ZnS nanoparticles by the transmission electron microscopy (TEM) test and the synthesized nanoparticle core and shell standard powder diffraction files (pdfs) in X-ray diffraction (XRD), the results of the studies showed that the methyl red due to its absorption spectrum overlapping with the emission spectrum of these quantum dots has a very powerful quenching effect on the emission of synthesized nanoparticles.
Shabnam Roshani, Hamide Ehtesabi, Zeinab Bagheri,
Volume 11, Issue 1 (3-2020)
Abstract
Mercury is one of the most harmful pollutants in the environment, which in the event of ingestion into the human body, it is not metabolized and severe nervous, respiratory and metabolic disorders will occur due to the formation of stable complexes with biological molecules. Therefore, the development of precise, fast and inexpensive methods for mercury detection in the environment is of great importance. Carbon quantum dot is a new fluorescent substance with unique physical and chemical properties which is taken into consideration for diagnostic applications, especially for heavy metals detection at low concentrations. In this study, carbon dots with blue fluorescent emission were synthesized using the pyrolysis method and characterized. Fluorescent emission intensity of synthesized carbon dots was decreased significantly in interacting with mercury. Then for providing an easy-to-use mercury detection method, carbon dot was encapsulated in sodium alginate hydrogel. Quenching fluorescent intensity of encapsulated carbon dots in the hydrogel structure was evaluated in the presence of mercury and 1micromolar detection limit was obtained. Encapsulating carbon dots in hydrogel structure not only extend the use of carbon dot as a mercury sensor but also can be used as an adsorbent for mercury pollutant from the environment.
Zahraa Neamah Abbas, Hanaa Naji Abdullah, Bijan Ranjbar,
Volume 15, Issue 2 (5-2024)
Abstract
In this study, 50 Staphylococcus aureus samples from Baghdad Hospital were collected and examined, 17 samples were infected with methicillin-resistant Staphylococcus aureus (MRSA) and 5 samples were infected with vancomycin-resistant Staphylococcus aureus (VRSA). The sensitivity of the isolates against different antimicrobial agents was evaluated using the VITEK2 standard system. According to CLSI, the minimum inhibitory concentration (MIC) values of zinc oxide quantum dots (ZnO-QDs) were also tested by the Muller-Hinton dilution method. In addition, polymerase chain reaction (PCR) was performed to identify vanA and mecA genes. The antibacterial effects of ZnO-QDs on VRSA were higher than MRSA isolates.
Volume 15, Issue 12 (2-2016)
Abstract
Accurate determination of the electro-elastic fields of quantum nanostructures within piezoelectric media is an important issue for realizing the electro-mechanical behavior of these nanostructures. In this paper, the governing partial differential equations corresponding to piezoelectric media containing quantum nanostructures are presented and subsequently, generalized analytical solutions based on Fourier series technique are developed for determination of the coupled electro-elastic fields in transversely isotropic piezoelectric barrier due to periodically distributed quantum nanostructures. The electro-elastic couplings of the piezoelectric barrier as well as the interactions between the quantum nanostructures are exhibited within the framework of the presented analytical solution. It is observed that no electric field and no electric potential will be induced anywhere in the medium for periodic distribution of quantum wires. The presented analytical solution is capable of treating different shapes and geometries of quantum wires/quantum dots. The electro-elastic fields of various shapes of sections of quantum wires and different geometries of quantum dots are studied and the effects of the geometry of periodically distributed quantum nanostructures are demonstrated. The results show that geometry of quantum nanostructures may highly affect the induced electro-elastic fields and therefore, accurate determination of the geometry of quantum nanostructures as well as the induced electro-elastic fields would be essential for employment of these nanostructures in different fields of research and technology.
Volume 19, Issue 127 (9-2022)
Abstract
Carbon quantum dots are a new generation of carbon nanoparticles that have good potential for food analysis and packaging due to their unique properties such as excellent fluorescence properties, easy synthesis, good biocompatibility, large functional groups, and low toxicity. Today, carbon quantum dots have replaced semiconductor quantum dots due to their non-toxicity. The use of carbon dots in packaging materials due to their antioxidant, antimicrobial and barrier properties increases product shelf life, reduces the growth of microorganisms, improves mechanical properties, the barrier against gases, UV light blocker, and reduces food waste. This paper aims to get acquainted with carbon quantum dots and synthesis methods and study their optical properties. Then, the principles of fluorescence sensor design, including the mechanism of fluorescence quenching and recovery and their application in food samples to detect food additives, pathogens, antibiotic residues, insecticides, heavy metals, and nutrients will be examined. Finally, the use of carbon dots in improved, active, intelligent and bio-packaging will then be discussed.
