ABSTRACT
In this work, an upconversion luminescence (UCL) nanosensor for fast detection of ferric ion (Fe3+) and phosphate ion (Pi) is developed based on the inner-filter effect (IFE) between NaYF4:Yb/Er upconversion nanoparticles (UCNPs) and Fe3+-hypocrellin B (HB) complex. Fe3+-HB complex has strong absorption band (450-650 nm), which overlaps with the green emission peak of UCNPs at 545 nm. By adding Fe3+ and Pi, the UCNPs-HB system produces the red-shift change of absorption spectrum, which leads to the "on-off-on" process of IFE. So, with the specific recognition ability of HB for Fe3+ and the competitive complexation of Pi for Fe3+, the proposed nanosensor utilizes the UCL change to achieve the detection of the targets. For the detections of Fe3+, the linear range is 10-600 µM with a limit of detection (LOD) of 2.62 µM, and for Pi, the linear range is 5-100 µM with a LOD of 1.25 µM. The results for selectivity, precision, and recovery test are also satisfactory. Furthermore, the real sample detection shows that the proposed nanaosensor has a great potential in environmental and biological systems. An upconversion luminescence (UCL) nanosensor based on the inner-filter effect (IFE) between upconversion nanoparticles (UCNPs) and Fe3+-hypocrellin B (HB) complex for the detection of Fe3+ and phosphate ion has been proposed, which is promising to be a convenient and sensitive assay for monitoring Fe3+ and phosphate ion in different environments and biological systems.
ABSTRACT
Based on the mechanism of luminescence resonance energy transfer (LRET) and using a special single strand DNA as the recognition element, a portable paper-based sensor for the accurate detection of total heavy rare-earth ions (mainly Gd3+, Tb3+ and Dy3+) concentration was proposed. The RNA cleaving-DNAzyme should recognize rare-earth ions to cleave RNA on DNA duplexes linking UCNPs and AuNPs, causing UCNPs and AuNPs to approach each other, inducing LRET, which attenuated the green upconversion luminescence (UCL) triggered by the 980 nm laser. UCL was captured by a charge-coupled device (CCD) image sensor and processed with the red-green-blue (RGB) image to quantitatively analyze heavy rare-earth ions in the samples. In the range of 5-50 µmol·L-1, the sensor has good sensitivity, with the limit of detection of 1.26 µmol L-1.
ABSTRACT
Thyroid-stimulating hormone (TSH) plays a crucial physiological and pathological role in humans, and a timely and sensitive detection of TSH is critical for early diagnosis and prevention of thyroid-related diseases. Herein, we developed a simple wash-free biological aptasensor based on luminescence resonance energy transfer (LRET) between NaYF4:Yb,Er upconversion nanoparticles (UCNPs) and tetramethylrhodamine (TAMRA) for the detection of TSH with high sensitivity. In this LRET system, UCNPs as donors and TAMRA as receptors were modified with nucleic acid aptamers Apt-1 and Apt-2, respectively. When TSH was present, the two aptamer strands both specifically recognized TSH to form a hairpin-like structure, thereby shortening the space between UCNPs and TAMRA. The LRET occurred under radiation of 980-nm light. By detecting the change of upconversion luminescence (UCL) intensity (I545nm), the activity of TSH was quantified. The resulting detection dynamic range and the limit of detection were 0.1-5.0 mIU·L-1 and 0.065 mIU·L-1, respectively. The aptasensor using UCNPs as LRET donors was capable of effectively eliminating the background interference of a complicated biological environment, and showed good specificity because of the excellent recognition function of aptamers. Due to high sensitivity, easiness of fabrication, operational convenience, and selectivity, the UCL-based aptasensor is a promising candidate for clinical TSH determination. Based on nucleic acid aptamer and the mechanism of luminescence resonance energy transfer (LRET) between upconversion nanoparticles (UCNPs) donor and tetramethylrhodamine (TAMRA) receptor, an aptasensor was constructed for the quantitative analysis of TSH activity in serum by testing the change of I545nm.
