PEG Coated Biocompatible Cadmium Chalcogenide Quantum Dots for Targeted Imaging of Cancer Cells (original) (raw)
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Biochemistry and Biophysics Reports, 2021
Quantum dots (QDs) are nanocrystals of semiconducting material possessing quantum mechanical characteristics with capability to get conjugated with drug moieties. The particle size of QDs varies from 2 to 10 nm and can radiate a wide range of colours depending upon their size. Their wide and diverse usage of QDs across the world is due to their adaptable properties like large quantum yield, photostability, and adjustable emission spectrum. QDs are nanomaterials with inherent electrical characteristics that can be used as drug carrier vehicle and as a diagnostic in the field of nanomedicine. Scientists from various fields are aggressively working for the development of single platform that can sense, can produce a microscopic image and even be used to deliver a therapeutic agent. QDs are the fluorescent nano dots with which the possibilities of the drug delivery to a targeted site and its biomedical imaging can be explored. This review is mainly focused on the different process of synthesis of QDs, their application especially in the areas of malignancies and as a theranostic tool. The attempt is to consolidate the data available for the use of QDs in the biomedical applications.
Bio-Mediated Synthesis of Quantum Dots for Fluorescent Biosensing and Bio-Imaging Applications
Materials research foundations, 2021
Quantum dots (QDs) have received great attention for development of novel fluorescent nanoprobe with tunable colors towards the near-infrared (NIR) region because of their unique optical and electronic properties such as luminescence characteristics, wide range, continuous absorption spectra and narrow emission spectra with high light stability. Quantum dots are promising materials for biosensing and single molecular bio-imaging application due to their excellent photophysical properties such as strong brightness and resistance to photobleaching. However, the use of quantum dots in biomedical applications is limited due to their toxicity. Recently, the development of novel and safe alternative method, the bio-mediated greener approach is one of the best aspects for synthesis of quantum dots. In this Chapter, bio-mediated synthesis of quantum dots by living organisms and biomimetic systems were highlighted. Quantum dots based fluorescent probes utilizing resonance energy transfer (RET), especially Förster resonance energy transfer (FRET), bioluminescence resonance energy transfer (BRET) and chemiluminescence resonance energy transfer (CRET) to probe biological phenomena were discussed. In addition, quantum dot nanocomposites are promising ultrasensitive bioimaging probe for in vivo multicolor, multimodal, multiplex and NIR deep tissue imaging. Finally, this chapter provides a conclusion with future perspectives of this field.
Journal of Luminescence, 2015
We demonstrate the usefulness of surfactant coated CdSe quantum dots in bio-imaging applications after evaluating their steady state and time resolved emission responses. The surfactant coated QDs, with the respective sizes of $ 14 nm and 10 nm are synthesized considering two different types of coating agents, namely, thio-glycolic acid (TGA) and sodium dodecyl sulfate (SDS). The steady state luminescence response is characterized by both near band edge (NBE) and defect-related emissions, but with a strong dependency on the nature of surfactant coating. Time resolved photoluminescence (TR-PL) studies have revealed bi-exponential characteristics with CdSe-TGA QDs exhibiting longer life time decay parameters than those of CdSe-SDS QDs. To be specific, the fast (τ 1 ) and the slow (τ 2 ) components are characterized by $ 10 and 30 times larger values in the former than the latter case. In the FT-IR spectra, several stretching and bending vibrations are observed to be adequately influenced by the nature of surfactant coating. The availability of plentiful Na þ counter ions around SDS coated QDs, as evident from the FT-IR spectroscopy studies, can also be responsible for obtaining reduced size of the QDs. In contrast, Raman active modes are apparently distinguishable in TGA coated QDs, with LO and TO mode positions significantly blue-shifted from the bulk values. While attributing to the intense defect mediated emission of TGA coated QDs, the effect of TGA coating presented a stronger fluorescence imaging capability over the SDS coated ones. A detailed assessment of fluorescent counts, as a basis of bioimaging response, is being discussed on a comparative basis.
Bioconjugated quantum dots for in vivo molecular and cellular imaging☆
Advanced Drug Delivery Reviews, 2008
Semiconductor quantum dots (QDs) are tiny light-emitting particles on the nanometer scale, and are emerging as a new class of fluorescent labels for biology and medicine. In comparison with organic dyes and fluorescent proteins, they have unique optical and electronic properties, with size-tunable light emission, superior signal brightness, resistance to photobleaching, and broad absorption spectra for simultaneous excitation of multiple fluorescence colors. QDs also provide a versatile nanoscale scaffold for designing multifunctional nanoparticles with both imaging and therapeutic functions. When linked with targeting ligands such as antibodies, peptides or small molecules, QDs can be used to target tumor biomarkers as well as tumor vasculatures with high affinity and specificity. Here we discuss the synthesis and development of state-of-the-art QD probes and their use for molecular and cellular imaging. We also examine key issues for in vivo imaging and therapy, such as nanoparticle biodistribution, pharmacokinetics, and toxicology.
Biofunctional quantum dots as fluorescence probe for cell-specific targeting
Colloids and Surfaces B: Biointerfaces, 2014
We describe here the synthesis, characterization, bioconjugation, and application of water-soluble thioglycolic acid TGA-capped CdTe/CdS quantum dots (TGA-QDs) for targeted cellular imaging. Antihuman epidermal growth factor receptor 2 (HER2) antibodies were conjugated to TGA-QDs to target HER2-overexpressing cancer cells. TGA-QDs and TGA-QDs/anti-HER2 bioconjugates were characterized by fluorescence and UV-Vis spectroscopy, X-ray diffraction (XRD), hydrodynamic sizing, electron microscopy, and gel electrophoresis. TGA-QDs and TGA-QDs/anti-HER2 were incubated with cells to examine cytotoxicity, targeting efficiency, and cellular localization. The cytotoxicity of particles was measured using an MTT assay and the no observable adverse effect concentration (NOAEC), 50% inhibitory concentration (IC 50 ), and total lethal concentration (TLC) were calculated. To evaluate localization and targeting efficiency of TGA-QDs with or without antibodies, fluorescence microscopy and flow cytometry were performed. Our results indicate that antibody-conjugated TGA-QDs are well-suited for targeted cellular imaging studies.
Quantum dots as fluorescent bio-labels in cancer diagnostic
2006
In this work we present and discuss some results concerning the application of colloidal semiconductor quantum dots for cancer diagnostic. We have prepared and applied different core-shell semiconductor quantum dots such as Cadmium Teluride-Cadmium Sulfide (CdTe-CdS) and Cadmium Sulfide -Cadmium Hydroxide (CdS/Cd(OH) 2 ). For the purpose of diagnostic with living cells, the CdS/Cd(OH) 2 presented best results, maintaining high levels of luminescence as well high stability in biological media. The quantum dots were obtained in aqueous medium, by reacting Cd 2+ and S 2in the presence of sodium polyphosphate as the stabilizing agent. Subsequent surface passivation with Cd(OH) 2 was carried out to improve luminescence. At a pH of 7,2 the quantum dots were functionalized with a 0.01% glutaraldehyde solution and then, incubated with living healthy and neoplastic cells (glial, glioblastoms and cervical) and tissues (breast) in culture medium. Tissue and cell staining were evaluated by the laser scanning confocal microscopy. Fluorescence Microscopy was used as a primary tool in order to explore the labeling of the samples. The procedure presented in this work, shown to be very efficient as a potential tool for fast and precise cancer diagnostic.
Semiconductor quantum dots in chemical sensors and biosensors
Nanosensors for Chemical and Biological Applications, 2014
Quantum dots are nanometre-scale semiconductor crystals with unique optical properties that are advantageous for the development of novel chemical sensors and biosensors. The surface chemistry of luminescent quantum dots has encouraged the development of multiple probes based on linked recognition molecules such as peptides, nucleic acids or small-molecule ligands. This review overviews the design of sensitive and selective nanoprobes, ranging from the type of target molecules to the optical transduction scheme. Representative examples of quantum dot-based optical sensors from this fastmoving field have been selected and are discussed towards the most promising directions for future research.
International journal of molecular sciences, 2008
Fluorescent probes that emit in the near-infrared (NIR, 700-1,300 nm) region are suitable as optical contrast agents for in vivo fluorescence imaging because of low scattering and absorption of the NIR light in tissues. Recently, NIR quantum dots (QDs) have become a new class of fluorescent materials that can be used for in vivo imaging. Compared with traditional organic fluorescent dyes, QDs have several unique advantages such as size- and composition-tunable emission, high brightness, narrow emission bands, large Stokes shifts, and high resistance to photobleaching. In this paper, we report a facile method for the preparation of highly fluorescent, water-soluble glutathione (GSH)-coated NIR QDs for in vivo imaging. GSH-coated NIR QDs (GSH-QDs) were prepared by surface modification of hydrophobic CdSeTe/CdS (core/shell) QDs. The hydrophobic surface of the CdSeTe/CdS QDs was exchanged with GSH in tetrahydrofuran-water. The resulting GSH-QDs were monodisperse particles and stable in ...
International Journal of Nanoscience, 2011
Quantum Dots (QDs) are recently emerging as the alternative to organic fluorescent probes in bio imaging applications. In the present study, CdTe QDs were prepared in aqueous phase using a stable tellurium source in presence of a capping agent capable of stabilizing and regulating its growth in the pH range of 6.0–8.0, such that it is amenable for use in biological systems. The spectroscopic and microstructural studies confirmed the formation of CdTe nanoparticles capped by mercaptosuccinic acid (MSA) of average size 2.5 nm with narrow size distribution. These MSA– CdTe QDs have shown tunable fluorescence with high quantum yield, broad absorption and symmetric fluorescence spectra. Of the different QDs emitting varied luminescence, the yellow, orange and red QDs were taken up for further characterization, to assess their potential in bioimaging applications. The cytotoxicity assays in mammalian lymphocytes showed that these QDs have a very high order cell viability and low level of ...