Národní úložiště šedé literatury Nalezeno 3 záznamů.  Hledání trvalo 0.00 vteřin. 
Photon-upconversion nanoparticles for single-molecule immunosensing of cancer biomarkers and bacteria
Farka, Z. ; Mickert, M. J. ; Hlaváček, Antonín ; Poláchová, V. ; Kostiv, Uliana ; Pastucha, M. ; Horák, Daniel ; Gorris, H. H. ; Skládal, P.
The recent progress in the field of immunoassays has been driven by introduction of various kinds of nanomaterials. In particular, photon-upconversion nanoparticles (UCNPs) proved to be excellent immunoassay labels due to their ability to emit light of shorter wavelengths under near-infrared excitation (anti-Stokes emission), which prevents autofluorescence, minimizes light scattering, and thus reduces the optical background interference. These unique photoluminescent properties allow counting of individual biomolecules labeled with UCNPs by conventional wide-field epiluminescence microscopy and enable the development of single-molecule (digital) immunoassays. We have introduced a novel label based on UCNPs conjugated with streptavidin via poly(ethylene glycol) and applied it in a digital upconversion-linked immunosorbent assay (ULISA) for the detection of a cancer biomarker prostate specific antigen (PSA). The digital readout based on counting of individual immunocomplexes improved the sensitivity 16× compared to conventional analog readout and allowed to reach a limit of detection (LOD) of 23 fg·mL−1 (800 aM). Human serum samples were successfully analyzed achieving an excellent correlation with electrochemiluminescence reference method. The conjugates of UCNPs with streptavidin are also suitable for the detection of pathogenic bacterium Melissococcus plutonius, the causative agent of honeybee disease European foulbrood. The ULISA assay provided an LOD of 340 CFU·mL−1 and successfully analyzed real samples of bees, larvae and bottom hive debris. Due to the high reliability and relatively simple detection scheme, the digital ULISA can pave the way for a new generation of digital immunoassays with a strong potential for commercialization.
Photon-upconverting nanoparticles as a novel background-free label in immunoassays
Farka, Z. ; Hlaváček, Antonín ; Mickert, M. J. ; Skládal, P. ; Gorris, H. H.
Photon-upconverting nanoparticles (UCNPs) have become an attractive label in immunoassays because their anti-Stokes luminescence can be excited by the NIR laser and detected in the VIS region without optical background interference. Further advantages of UCNPs include good photostability, large anti-Stokes shifts, and multiple narrow emission bands that can be used for multiplexed detection. We have developed a competitive upconversion-linked immunosorbent assay (ULISA) for detection of the pharmaceutical diclofenac (DCF) in surface waters. Silica-coated UCNPs (50 nm in diameter) with carboxyl groups on the surface were synthesized and conjugated with the secondary anti-IgG antibody. The structure and monodispersity of the nanoconjugates was studied by TEM and agarose gel electrophoresis. Using a highly affine anti-DCF primary antibody, the optimized ULISA provided a detection limit of 50 pg·mL−1.
Nanostructured gold electrodes for determination of glucose in blood
Farka, Z. ; Juřík, T. ; Kovář, D. ; Podešva, Pavel ; Foret, František ; Skladal, P.
Fast and sensitive devices for monitoring of glucose are crucial in today’s medicine. Most of the commercial glucometers are currently based on enzymatic catalysis which provides reasonable sensitivity but has a drawback in limited enzyme stability. With the development of novel surfaces, new generation of non-enzymatic sensors characterized by high sensitivity and stability is emerging. In this work, gelatin-templated nanostructured gold electrodes were developed and applied for non-enzymatic glucose determination. The analysis was done by direct electrochemical oxidation during cyclic voltammetry and amperometry with the limit of detection at 1.3 μM. The ability to detect physiological levels glucose in presence of interferents was demonstrated on deproteinized human blood serum.

Chcete být upozorněni, pokud se objeví nové záznamy odpovídající tomuto dotazu?
Přihlásit se k odběru RSS.