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Nanobiotechnology, IEE Proceedings -

Issue 2 • Date 8 April 2005

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Displaying Results 1 - 6 of 6
  • Resonant nano-cluster devices

    Publication Year: 2005 , Page(s): 53 - 63
    Cited by:  Patents (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (935 KB)  

    The resonance-enhanced absorption (REA) by metal clusters on a surface is an effective technique on which to base bio-optical devices. A four-layer device consisting of a metal mirror, a polymer or glass-type distance layer, a biomolecule interaction layer and a sub-monolayer of biorecognitively bound metal nano-clusters is reported. Experiments indicate a strong influence of the resonator homogeneity on the absorption maximum. Layer stability plays an important role in the overall performance of the device. Techniques and optimised lab protocols to set up biochips that use the REA process in the detection are presented. The sensors show one to three narrow reflection minima in the visible and or infra-red (IR) part of the spectrum and therefore they do not suffer from the spectral limitations associated with spherical gold colloids. Metal clusters (synthesised by thermal step reduction) as well as metal- dielectric shell clusters (synthesised by various shell deposition processes) are used to precisely shift the readout of the device to any frequency in the visible and near IR range. Disposable single-step protein chips, DNA assays as well as complex biochip arrays are established that use various DNA/RNA, antigen-antibody and protein-protein interaction systems. View full abstract»

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  • Infrared up-converting phosphors for bioassays

    Publication Year: 2005 , Page(s): 64 - 72
    Cited by:  Papers (2)  |  Patents (13)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (796 KB)  

    The development of up-converting phosphor reporter particles has added a powerful tool to modern detection technologies. Carefully constructed phosphor reporters have core-shell structures with surface functional groups suitable for standard bio-conjugations. These reporters are chemically stable, possess the unique property of infrared up-conversion, and are readily detected. In contrast to conventional fluorescent reporters, up-converting phosphor particles do not bleach and allow permanent excitation with simultaneous signal integration. A large anti-Stokes shift (up to 500 nm) separates discrete emission peaks from the infrared excitation source. Along with the unmatched contrast in biological specimens due to the absence of autofluorescence upon infrared excitation, up-converting phosphor technology (UPT) has unique properties for highly-sensitive particle-based assays. The production and characteristics of UPT reporter particles as well as their application in various bioassays is reviewed. View full abstract»

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  • Encapsulation in sub-micron species: a short review and alternate strategy for dye encapsulation

    Publication Year: 2005 , Page(s): 73 - 84
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (885 KB)  

    The encapsulation of molecular species has received considerable attention in recent years. Polymers, dendrimers and microemulsions along with other systems have been used as precursors for the synthesis of encapsulating agents. Especially important in this field is the core-shell architecture. This structure offers the encapsulated species an extra level of protection due to the presence of a shell, covering the interior of a capsule. Dyes, porphyrines, drugs, cells and other active agents have been successfully encapsulated, and the host-guest interaction has been studied by various experimental techniques. A review is new provided of the progress made in this field in the last several years is presented. Different classes of synthetic approaches are presented and resulting encapsulation studies are summarised. An approach to the encapsulation of dansyl chloride dye in core-shell nanoparticles is also presented. View full abstract»

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  • Selective enzymatic cleavage of gold nanoparticle-labelled DNA on a microarray

    Publication Year: 2005 , Page(s): 85 - 88
    Cited by:  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (327 KB)  

    The use of the restriction enzyme EcoRI for the manipulation of double-stranded DNA on microarrays is introduced. Gold nanoparticles are attached to a microarray via base pairing between complementary DNA sequences on the array and on the particles. These particles could be detected by light scattering measurements following an enhancement step, in which silver islands were deposited on top of the gold particles. This deposition of silver could be completely suppressed if the particles were removed by enzymatic cleavage of their DNA linker molecules. This cleavage step critically depends on the presence of a specific enzyme recognition site. View full abstract»

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  • Ligand-installed PEGylated bionanosphere

    Publication Year: 2005 , Page(s): 89 - 96
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (443 KB)  

    The synthesis of poly(ethylene glycol)-b-poly(2-N,N-dimethylaminoethylmethacrylate) processing an acetal group at the PEG chain end (acetal-PEG/PAMA) is reported. The obtained acetal-PEG/PAMA block copolymer was found to reduce tetrachloroauric acid at room temperature to produce gold nanoparticles. The size of these nanoparticles was controllable in the range of 6 to 13 nm by changing the initial Au3+: polymer ratio. In addition to the reduction of tetrachloroauric acid, acetal-PEG/PAMA bonds on the surface of the obtained gold nanoparticles to improve their dispersion stability in an aqueous medium even at a salt concentration as high as two. Biotinyl-PEG/PAMA-anchored gold nanoparticles undergo specific aggregation in the presence of streptavidin thereby revealing their promising utility as colloidal sensing systems for use in biological systems. Biotin-PEG/PAMA can also be utilised for the preparation of a functionally PEGylated quantum dot (QD). When CdCl2 and Na2S were mixed in aqueous media in the presence of the biotin-PEG/PAMA, a CdS QD with an ∼5 nm size was prepared. The polyamine segment was anchored onto the surface of the formed CdS nanoparticle, whereas the PEG segment was tethered onto the surface to form a hydrophilic palisade, thus improving the dispersion stability in aqueous media even under a high salt concentration condition. An effective fluorescent resonance energy transfer (FRET) was observed by the specific interaction of the biotin-PEG/PAMA stabilised CdS QD with TexasRed-labelled streptavidin with the physiological ionic strength of 0.15 M. The extent of the energy transfer was in proportion to the concentration of the TexasRed-streptavidin. This FRET system using the PEGylated CdS QD coupled with fluorescent-labelled protein can be utilised as a highly sensitive bioanalytical system. View full abstract»

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  • Gold-nanoparticle-assisted oligonucleotide immobilisation for improved DNA detection

    Publication Year: 2005 , Page(s): 97 - 103
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (631 KB)  

    Colloidal gold nanoparticles are investigated as a potential scaffold for the assisted immobilisation of probe oligonucleotides on silicon surfaces. A preliminary study is devoted to the examination of the immobilisation of DNA-modified gold nanoparticles as a function of time, concentration, salt and pH. The DNA-modified nanoparticles self-assembled onto solid surfaces in a three-dimensional self-assembled architecture. The functionalised surfaces are evaluated in diagnostic assays, where their potential to improve the efficiency of the hybridisation reaction is tested. The system utilising DNA-modified nanoparticles produced an enhancement in the hybridisation efficiency and the sensitivity limit by a factor 10 to 100 as compared to a conventional DNA immobilisation system on a planar surface. View full abstract»

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