Detection of Bioconjugated Quantum Dots Passivated with Different Ligands for Bio-Applications

Abstract

Bioconjugation of quantum dots has resulted in a significant increase in resolution of biological fluorescent labeling. This intrinsic property of quantum dots can be utilized for sensitive detection of target analytes with high sensitivity; including pathogenic bacteria and cancer monitoring. The quantum dots and quantum dot doped silica nanoparticles exhibit prominent emission peaks when excited at 400 nm but on conjugation to model rabbit antigoat antibodies exhibit diminished intensity of emission peak at 600 nm. It shows that photoluminescence intensity of conjugated quantum dots and quantum dot doped silica nanoparticles could permit the detection of bioconjugation. Samples of conjugated and unconjugated quantum dots and quantum dot doped silica nanoparticles were subjected to enzyme linked immunosorbent assay for further confirmation of bioconjugation. In the present study ligand exchange, bioconjugation, fluorescence detection of bioconjugated quantum dots and quantum dot doped silica nanoparticles and further confirmation of bioconjugation by enzyme linked immunosorbent assay has been described.

<p>Development of biosurfactant-based graphene quantum dot conjugate as a novel and fluorescent theranostic tool for cancer</p>

“…GQDs-biosurfactant conjugates (biosurfactant-GQDs) were separated from free cross-linkers by centrifugation (6,000 rpm, 5 minutes) and kept at 4°C. 1,23…”

“…Finally, purified folate conjugated GQDs (FA-biosurfactant-GQDs) were stored at 4°C till further use. 1,23,32 characterization GQDs and their bioconjugates were characterized by spectrophotometeric techniques such as transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and zeta potential. The optical studies were investigated by PL and UV-visible spectroscopy.…”

“…QDs are integrated with various biomolecules for specific targeting and purposes in the field of biological and medical sciences. 1 This is because of their small size, narrow emission spectra over broad excitation spectra, high fluorescent quantum yields, and resistance to photo-bleaching. 2,3 Earlier, metallic QDs such as CdS, CdSe, and CdTe were the most investigated QDs due to their excellent optical and electrochemical properties.…”

“…These nanoconjugates exhibit targetability and have imaging properties enabling them to be used in downstream screening purposes. 1 Very recently, by utilizing unique physicochemical properties of GQDs, Ding et al had developed a novel type of theranostic agent by loading anticancer drug doxorubicin (DOX) to GQD's surface and conjugating Cy5.5 (Cy) dye to GQD through a cathepsin D-responsive (P) peptide. Authors reported superior therapeutic performance of this type of agents along with functioning as probes for tracking the delivery and release of anticancer drug as well as drug-induced cancer cell apoptosis.…”

Toxicity assessment of repeated intravenous injections of arginine&ndash;glycine&ndash;aspartic acid peptide conjugated CdSeTe/ZnS quantum dots in mice

“…These functional QD probes have been increasingly used in cellular and molecular tracing, in vivo tumor imaging, drug monitoring, and signal transduction. [3][4][5][6][7][8] Since the core components of QDs are heavy metals (such as Cd, Se, and so on), their toxicity and biosafety have aroused general concern. 9,10 Some studies have shown that due to the release of heavy metals from the QD core and the generation of reactive oxygen free radicals induced by QDs in cells, QDs are toxic to the organism and cells.…”