Nanoparticles functional

Finally, gold nanoparticles functionalized with thiols have emerged as a very interesting field of research. The gold particle is used as a core to which thiols are attached and the melting of the chains can give rise to LC-like behavior on the gold surface or to real mesophases. 

The third group of Au NP-biomolecule interactions are referred to as specific affinity interactions and include nanoparticles functionalized with groups that provide affinity sites for the binding of bio molecules such as proteins and oligonucleotides. 

Figure 12.25 (a) Assembly of a Au nanoparticles wire in the poly A/polyT template using Au nanoparticles functionalized with intercalator (psoralen) molecules, (b) AFM image of the Au nanoparticles wire in the poly A/polyT template. Reproduced with permission from Ref. 91. Copyright Wiley-VCH Verlag GmbH Co. KGaA. 

Bisaniline-cross-linked gold nanoparticles functionalized with thiophenylboronic acid... 

Gorin DA, Portnov SA, Inozemtseva OA et al (2008) Magnetic/gold nanoparticle functionalized biocompatible microcapsules with sensitivity to laser irradiation. Phys Chem Chem Phys 10 6899-6905... 

Taton et al. used gold nanoparticles functionalized with thiol-modified oligonucleotides to detect the presence of its complementary sequence hybridized on a transparent substrate (Fig. 13.9).16 In comparison to conventional fluorophore probes, this technique is three times more sensitive in discriminating an oligonucleotide sequence with a single basepair mismatch. In addition, signal amplification by reduction of silver ions on the nanoparticles drastically increased the sensitivity of... 

CNTs and other nano-sized carbon structures are promising materials for bioapplications, which was predicted even previous to their discovery. These nanoparticles have been applied in bioimaging and drag delivery, as implant materials and scaffolds for tissue growth, to modulate neuronal development and for lipid bilayer membranes. Considerable research has been done in the field of biosensors. Novel optical properties of CNTs have made them potential quantum dot sensors, as well as light emitters. Electrical conductance of CNTs has been exploited for field transistor based biosensors. CNTs and other nano-sized carbon structures are considered third generation amperometric biosensors, where direct electron transfer between the enzyme active center and the transducer takes place. Nanoparticle functionalization is required to achieve their full potential in many fields, including bio-applications. 

With specifically captured nanoparticles able to act as a scaffold for the reductive deposition of silver, a change in resistance between two electrodes can be implemented as an alternative detection mechanism. Hybridization between probe and target is used to direct nanoparticle-functionalized tags to the microscale gap between electrodes and subsequent exposure to silver deposition creates a continuous conductive contact (Fig. 2d). Detection of hy-... 

Vlckova et al. demonstrated single-molecule SERS in self-assembled dimers of silver nanoparticles [161]. The self-assembly process was driven by nanoparticle functionalization with a bifunctional molecular linker (4,4 -diaminoazobenzene) which forms a molecular bridge between the particles. Molecules forming the molecular bridge are then precisely positioned within the hot spot with the molecular population being controlled by careful optimization of the linker to... 

Irudayaraj et al. have reported the multiplex detection of up to eight different non-fluorescent nanoparticles functionalized with one sequence of DNA [61]. In this approach, a thiolated sequence of DNA was used to functionalize the surface of gold nanoparticles and then non-fluorescent Raman reporters were added to the surface of the nanoparticle to code them with a SERS signal. It was reported that multiplex detection of two, four, and eight differently labeled nanoparticles could be detected in one analysis. However, only one DNA sequence was used in this study to label all the different flavors of nanoparticles and the detection of a specific, target DNA sequence by SERS was not reported. However, it was possible to observe the change in surface plasmon by UV-Vis spectroscopy when two batches of nanoparticles functionalized with complementary sequences were hybridized together. 

Recent work has been published on the use of SERS reporters for in vivo analysis. In 2008, Shuming Nie published work on the in vivo targeting of tumors in live mice [65]. The SERRS particles consisted of 60 nm gold nanoparticles functionalized with a Raman reporter dye molecule and then stabilized with thiolated polyethylene glycols (PEGs). Targeted SERS nanoparticles were prepared by having a mixed monolayer of thiolated PEG and a heterofunctional thiolated PEG with a carboxylic... 

Another recent article by Kneipp et al. demonstrates the use of multiplexing within live cells [69]. Two different SERS particles, aggregates of metal nanoparticles functionalized with two different reporter molecules could be imaged within cells using SERS. The data obtained was analyzed using cluster methods and principal components analysis to detect the two SERS reporters within the live cells. 

Other than for diagnostic purposes, SERS-active nanoparticles may be used also for therapeutic aims. Nanohybrids consisting of gold (or silver) colloidal nanoparticles functionalized with drugs may be inserted in living cells and detected by SERS microspectroscopy. Thus, two goals may be reached first, the drug is localized inside the cellular structures and, second, the action mechanism may be discovered. 

Fig. 3 Pre- and postfunctionalization routes leading to functional hybrid metal or oxide clusters and nanoparticles. Functional hybrids are the nanobuilding blocks (NBB) of complex hierarchical structures.

Baba K, Kaneko T, Hatakeyama R et al (2010) Synthesis of monodispersed nanoparticles functionalized carbon nanotubes in plasma-ionic liquid interfadal fields. Chem Commun 46 255-257... 

Goodman, C. M., McCusker, C. D., Yilmaz, T., and Rotello, V. M. (2004). Toxicity of gold nanoparticles functionalized with cationic and anionic side chains. Bioconjug Chem 15, 897-900. 

Nanoparticles Functionalized with Bioactive Molecules Biomedical Applications... 

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