Labelling with Nanoparticles

Attachment of magnetic nanoparticles to antibodies that label specific proteins, as shown in Fig. 8.6, is now a possibility [17], Once the particles bind to proteins through highly specific antibody protein complementarity the entire nanoassembly becomes magnetically aligned in the presence of an external magnetic field  

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Another recent study highlighting a redox-active label employs metal colloids to signal target-probe hybridization. Magnetic beads derivatized with single-stranded DNA probe sequences were used to capture target and reporter sequences that had been labeled with nanoparticles composed of ZnS, PbS, or CdS. The beads were then physically removed from the analyte solution, and the particles were dissolved in acid. After adsorption of these ions onto solid electrodes, stripping voltammetry was used to quantify the... 

Nanoparticles such as those of the heavy metals, like cadmium selenide, cadmium sulfide, lead sulfide, and cadmium telluride are potentially toxic [14,15]. The possible mechanisms by which nanoparticles cause toxicity inside cells are schematically shown in Fig. 2. They need to be coated or capped with low toxicity or nontoxic organic molecules or polymers (e.g., PEG) or with inorganic layers (e.g., ZnS and silica) for most of the biomedical applications. In fact, many biomedical imaging and detection applications of QDs encapsulated by complex molecules do not exhibit noticeable toxic effects [16]. One report shows that the tumor cells labeled with QDs survived in circulation and extravasated into tissues... 

FIGURE 14.1 Scanometric DNA array detection with enlarged nanoparticle probes. Use of oligonucleotide targets, labeled with gold nanoparticles, for recognizing DNA segments on a chip (reproduced from [13] with permission). 

Soukka T, Paukkunen J, Harma H, Lonnberg S, Lindroos H, Lovgren T (2001) Supersensitive time-resolved immunofluorometric assay of free prostate-specific antigen with nanoparticle label technology. Clin Chem 47 1269-1278... 

Fig. 30 Representative scheme for the signal amplification concept by increasing the number of fluorophores per binding site in an antigen-antibody sandwich assay, (a) Binding of a labeled antibody to the target analyte yields a moderate fluorescence signal because the antibody is labeled with only few fluorophores (b) For the same binding event, the emission signal is dramatically amplified when using an antibody labeled with a nanoparticle that is doped with a large number of fluorophores...

Figure 3.9 Schematic representation of the typical noncovalent CNT functionalizations and the hybrid approach by using pyrene linkers. The figure also shows transmission electron images of SWNT modified with streptavidin labeled with 10 nm gold nanoparticles that were covalently coupled to pyrene linkers that were stacked on...

During sensor incubation in the antibody-containing solution, immunocomplex is formed on the sensor surface. Further incubation in the solution containing protein A labeled with silver nanoparticles results in protein A localization on the immunocomplex surface. In this case, silver quantity is determined by number of immunocomplexes having been formed on the sensor surface. A silver-generated signal may be conditioned by the presence of immunocomplex and silver par-ticles-labeled protein A, localized on it. 

It can be concluded that silver-oxidation current can be used as a signal-generating reaction for measuring the given antibody concentration in the test sample and the use of protein A labeled with silver nanoparticles is valid. 

Colloidal gold nanoparticles (10 nm) labeled with protein A, monoclonal and polyclonal antibodies to protein A, antihuman albumin, bovine serum,... 

The PAH polymeric layer played an important role in our fluorescence sensor design. First, its positive charges enabled the deposition of anionic dextran that was labeled with the pH indicator fluorescein on the surface of the nanoparticles. More importantly, the PAH polymeric layer separated between the fluorescein molecules and the metal particle. In fact, the thickness of the polymeric layer was over 10 nm, which is larger than the Forster distance required for efficient energy transfer between the fluorophore and the metallic gold particles. 

Valera, E., J. Ramdn-Azcon, FJ. Sanchez, et al. 2008. Conductimetric immunosensor for atrazine detection based on antibodies labelled with gold nanoparticles. Sens. Actuat. It Chem. 134 95-103. 

Fig. 7 (PLL/HA)24/PLL film with embedded DNA before (a, c) and after (b, d) irradiation with IR light. PLL in the film is labeled with FITC (a, b), and DNA is labeled with EtBr (c, d). Scale bars 5 pm. (e) Suggested mechanism of DNA release induced by the distortion of the DNA-doping PLL interaction as a result of partial thermal film decomposition in vicinity of nanoparticle aggregates. Reproduced from [98]...

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