Near-infrared Upconversion Nanoparticles Research Articles

Improvement of Photocatalytic Performance using Near-Infrared Upconversion Nanoparticles

Improvement of Photocatalytic Performance using Near-Infrared Upconversion Nanoparticles

Background-Free Chromatographic Detection of Sepsis Biomarker in Clinical Human Serum through Near-Infrared to Near-Infrared Upconversion Immunolabeling.

Luminescence nanomaterial-based lateral flow assay (LFA) is promising for point-of-care tests. However, the detection sensitivity and accuracy are often affected by the interferences of autofluorescence and photon scattering from nitrocellulose membrane and colored plasma. Here, we describe a near-infrared to near-infrared upconversion nanoparticle (UCNP) immunolabeled LFA for background-free chromatographic detection of sepsis biomarker procalcitonin (PCT) in clinical human plasma. This upconversion immunolabeling enables both light excitation (at ∼980 nm) and anti-Stokes emission (at 800 nm) to be adopted within the first biological window (700-1000 nm), which eliminates background autofluorescence as well as photon scattering interferences, empowering a high-sensitivity detection without complicated procedures. After optimization, the described assay presented a limit of detection reaching down to 0.03 ng/mL, lower than the normal level (0.05 ng/mL), while having a detection range of 0.03-50 ng/mL that covers the clinical PCT level of interest (0.5-10 ng/mL). The assay recoveries in human serum samples were evaluated to be about 95-110%, whereas the inter- and intra-assay coefficient variations were both determined to be below 15%. Importantly, measured PCT concentrations in clinical samples are in good correlation with that of the electrochemiluminescence immunoassay (Roche) widely applied in large clinical settings. This near-infrared to near-infrared upconversion immunolabeling approach has direct implications for ultrasensitive and background-free point-of-care detection of other serum biomarkers in resource-limited clinical settings.

A SPR aptamer sensor for mercury based on AuNPs@NaYF4:Yb,Tm,Gd upconversion luminescent nanoparticles

A new aptamer-based surface plasmon resonance system has been designed to detect Hg2+ that utilizes gold nanoparticle coated NaYF4:Yb,Tm,Gd near-infrared upconversion nanoparticles as probes.

A near-infrared magnetic aptasensor for Ochratoxin A based on near-infrared upconversion nanoparticles and magnetic nanoparticles

A multiplexed, sensitive and specific detection method is highly desirable for the simultaneous detection of several pathogenic bacteria and bio-toxins. In our previous work, multicolor upconversion nanoparticles (UCNPs) via doping with various rare-earth ions to obtain well-separated emission peaks by means of a solvothermal method were synthesized and were successfully applied as luminescence labels in the detection of three pathogenic bacteria. One of the basic achievements of our group has been to establish that the key to increasing the number of simultaneous detection components is the preparation of more UCNPs, the emission peaks of which can be distinguished from each other. According to this vision, NaYF4:Yb0.2, Tm0.02 UCNPs were obtained via a thermal-decomposition protocol, which has a main near-infrared (NIR) UC emission at 804nm under 980nm excitation. The emission peak at 804nm was well-separated from the emission peaks of UCNPs we have reported at 477nm, 542nm, and 660nm. It means both the excitation and the emission of NaYF4:Yb0.2, Tm0.02 UCNPs are located in the NIR spectral range (NIR-to-NIR UC emission), the so-called biological window. This result establishes the basis of achieving simultaneous detection of four components. To confirm the analytical performance of this NaYF4:Yb0.2, Tm0.02 UCNPs, a novel near-infrared magnetic aptasensor for the detection of Ochratoxin A (OTA) was developed using the OTA aptamer-conjugated near-infrared upconversion nanoparticles (apt-UCNPs) and the complementary oligonucleotide-modified magnetic nanoparticles (cDNA-MNPs). The apt-UCNPs and cDNA-MNPs were hybridized to form a poly-network structure of MNP-UCNP nanocomposites. When the target OTA was introduced, the aptamer combined with the priority target and the cDNA-MNPs were replaced. The proposed method achieved a linear range between 0.01 and 100ngmL−1, with a detection limit as low as 0.005ngmL−1. Then, we successfully applied this method to measure Ochratoxin A (OTA) in beer samples and the results demonstrated that the method possessed a high sensitivity and good selectivity for the determination of OTA and thus is applicable to the determination of OTA in beer samples. This satisfying result shows that the NaYF4:Yb0.2, Tm0.02 UCNPs we synthesized has a great prospect in multiplexed simultaneous detection.

Near-infrared upconversion nanoparticles for bio-applications

Upconversion nanoparticles (UCNs) attract intensive attentions in biomedical applications. They have shown great potential in bioimaging, biomolecule detection, drug delivery, photodynamic therapy and cellular molecules interactions. Due to the anti-Stokes optical property and NIR excitation, UCNs overcome the drawbacks encountered in conventional luminescent biomarkers. High signal to noise ratio, low cytotoxicity and stable high throughput results are obtained using UCNs as luminescent labels or light triggers in biomedical applications. In this review article, the reason for choosing UCNs as biomedical agents, the progress of the UCNs development and case studies of their biomedical applications will be discussed.

Monochromatic Near-Infrared to Near-Infrared Upconversion Nanoparticles for High-Contrast Fluorescence Imaging

To develop a fluorescent bioprobe for high-contrast deep tissue fluorescence imaging, monochromatic 800 nm upconversion emissions based on NaYF4: Yb3+, Tm3+ upconversion nanoparticles are investigated. The ratio of I800 to I470, which is used to describe the monochromaticity, showing exponential growth with the increase of Tm3+ doping concentration in NaYF4: Yb3+, Tm3+ nanoparticles, can reach as high as 757 at 4% Tm3+. At such a doping level, the absolute quantum efficiency can reach 3.9 × 10–3 as measured by a calibrated integrating sphere, which is sufficient for fluorescence imaging. High-contrast fluorescence phantom imaging was obtained by adjusting monochromaticity of 800 nm upconversion emission under the excitation of a 980 nm diode laser.