RESUMEN
Immunoassays are widely used in medicine, food, environment and other fields due to having the advantages of simpleness, rapidness and accuracy. Combining immunoassays with nanomaterials can improve the performance of immunoassays. Compared with traditional nanomaterials, upconversion nanoparticles (UCNPs) have excellent optical properties such as good photostability, long luminescence lifetime and narrow and tunable emission bands, which can significantly reduce background noise and improve analytical sensitivity when combined with immunoassay. This paper briefly introduces the luminescence mechanism of UCNPs, summarizes the synthesis and surface modification methods of UCNPs. And then 5 UCNPs-based immunoassay techniques, namely, fluorescence resonance energy transfer, inner filter effect, magnetic separation technique, upconversion-linked immunosorbent assay and upconversion immunochromatography, are discussed in detail. These sensing protocols of UCNPs-based immunoassays have been successfully utilized to detect various targets, including small molecules, macromolecules, and pathogens, all of which closely related to food safety, human health, and environmental pollution. Finally, the challenges and prospects of this technique are summarized and prospected. Although the UCNPs immunoassays based on antibodies and antigens have made great progress, most of the research is still in the stage of laboratory, and there is a long way to go to realize its social applications. There is a series of challenges need to be overcome. (1) Designing excellent water soluble and dispersive upconversion nanomaterials is needed. Hydrophilic ligands are bound to smaller upconversion nanoparticles and removing hydrophobic surface ligands are the most widely used methods to improve solubility and dispersity. (2) Multi-detection technology platforms and multi-mode simultaneous detection platforms have great potential, which will improve the efficiency of point of care detection. (3) The researchers also need to focus on some important problems. For examples, the upconversion luminescence efficiency of UCNPs is difficult to maintain, the synthesis method is complex, and the surface modification degree and functionalization are difficult to control.
RESUMEN
<p><b>AIM</b>To investigate the effect of triptolide on proliferation of PC12 cells and the mechanism involved in the effect, and provide evidence for clinical use of triptolide in treatment of tumor.</p><p><b>METHODS</b>By means of morphological observation, MTT assay, flow cytometry (FCM) and RT-PCR, the effect of triptolide on the proliferation of PC12 cells was observed in vitro.</p><p><b>RESULTS</b>The proliferation inhibition was found on PC12 cells incubated with triptolide (5 x 10(3) or 25 x 10(3) g/L) for 24 h, 48 h and 72 h, and with the higher concentration of triptolide, the inhibition was stronger. Low concentration of triptolide (1 x 10(3) g/L) showed no significant effect on proliferation of PC12 cells. After treatment of PC12 cells with triptolide (5 x 10(3) g/L) for 24 h, increased percentage of G0-G1 phase and decreased percentage of S phase were found. Expression of translational elongation factor 2A3-2 was reduced after treatment of PC12 cells with triptolide (5 x 10(3) g/L). The expression of 2A3-2 was weaker in PC12 cells treated with triptolide for 48 h than for 24 h.</p><p><b>CONCLUSION</b>Triptolide inhibits the proliferation of PC12 cells. The inhibition may be realized by changing the expression of 2A3-2 and preventing the transition from G0-G1 phase to S phase.</p>