Biofunctionalized indigo-nanoparticles as biolabels for the generation of precipitated visible signal in immunodipsticks.
ABSTRACT A novel class of organic nanoparticles as biolabels that can generate an instant visible signal was applied to immunodipsticks. A new principle for signal generation based on hydrolysis of colourless signal precursor molecules to produce coloured signal molecules followed by signal precipitation and localization was demonstrated. The nanoparticle biolabels were applied to sandwich immunoassays for the detection of mouse immunoglobulin G (M IgG). In the presence of M IgG, a nanoparticle-immunocomplex was formed and bound on the test zone immobilized with goat anti M IgG (Gt α M IgG). A blue line was developed on the test zone upon the addition of a signal developing reagent. An optical signal could be simply assessed using naked eyes or quantified using a reading device. The lowest visible signal that could be observed using naked eyes was found to be 1.25 μg L(-1) M IgG. The nanoparticle biolabel also showed a better sensitivity (signal-to-noise ratio) compared with the conventional colloidal gold biolabel. This novel class of organic nanoparticles offers an alternative biolabel system for the development of point-of-care immunodipsticks.
- SourceAvailable from: Georgette B. Salieb-Beugelaar[Show abstract] [Hide abstract]
ABSTRACT: Rapid, specific and sensitive diagnosis of infectious diseases is important for the rational, effective and economic treatment of the infection. Focused treatment of the patient with an accurate diagnosis may also contribute to the minimization of drug resistance development. Rapidly evolving micro and nanotechnologies contribute to the development of new diagnostic modalities. This critical review provides an overview of current developments in diagnostics for infectious disease enabled by nanotechnologies and includes a range of representative examples.European Journal of Nanomedicine 03/2014;
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ABSTRACT: Fluorene-based linear [small pi]-conjugated oligomers with different end functional groups having zero- (OF1), one- (OF2), two- (OF3) and three-point (OF4) hydrogen bonding sites were synthesized and characterized. By using a reprecipitation method, self-assembled nanoparticles were prepared in aqueous medium. The spherical shape and amorphous nature of nanoparticles were established by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. Zeta potential measurements showed that nanoparticles of OF2-4 have good colloidal stability, whereas those of OF1 have only moderate stability indicating that the hydrogen bonding groups in OF2-4 interact with the polar water molecules providing stability to the assembly. However, the interior of the nanoparticles remained non-polar, thus providing a conducive medium for hydrogen bonding between the oligofluorene molecules. This leads to varying interchromophore interactions in OF1-4 in the nanoparticle state depending on the H-bonding strength of the end groups. Dynamic light scattering (DLS) studies revealed that under identical conditions, the size of the nanoparticles decreased with increasing number of hydrogen bonding sites in the molecule. The interchromophore interactions were evident from the UV-Vis absorption and fluorescence studies. Bright blue fluorescence of the molecules in solution undergoes quenching in the nanoparticle state. The fluorescence quenching significantly increases from OF1 to OF4 indicating enhanced interaction between chromophores with increasing number of hydrogen bonding sites in the molecules. The nanoparticles were used as a donor scaffold for fluorescence resonance energy transfer (FRET) by encapsulating varying amounts of an orange red emitting neutral dye (D1) thereby achieving colour tunable emission including white. FRET studies were also conducted with a cationic dye (D2) adsorbed on the negatively charged nanoparticle surface. The FRET efficiency with both dyes showed direct correlation with the number of hydrogen bonding sites in the molecules.Journal of Materials Chemistry 01/2012; 22(22):11224-11234. · 6.63 Impact Factor
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ABSTRACT: Point-of-care (POC) diagnostics brings tests nearer to the site of patient care. The turnaround time is short, and minimal manual interference enables quick clinical management decisions. Growth in POC diagnostics is being continuously fueled by the global burden of cardiovascular and infectious diseases. Early diagnosis and rapid initiation of treatment are crucial in the management of such patients. This review provides the rationale for the use ofPOCtests in acute coronary syndrome, heart failure, human immunodeficiency virus, and tuberculosis. We also consider emerging technologies that are based on advanced nanomaterials and microfluidics, improved assay sensitivity, miniaturization in device design, reduced costs, and high-throughput multiplex detection, all of which may shape the future development of POC diagnostics. Expected final online publication date for the Annual Review of Analytical Chemistry Volume 6 is June 15, 2013. Please see http://www.annualreviews.org/catalog/pubdates.aspx for revised estimates.Annual Review of Analytical Chemistry (2008) 03/2013; · 7.81 Impact Factor