Amphiphilic Nanoaggregates with Bimodal MRI and Optical Properties Exhibiting Magnetic Field Dependent Switching from Positive to Negative Contrast Enhancement

A nanomaterial-independent and fluorescent immunoassay based on Eu-micelles for rapid and sensitive detection of fluoroquinolones in chicken

Fluorescent nanoprobes are widely applied in innovate enzyme-linked immunosorbent assays (ELISA) for detection of fluoroquinolones (FQs) residue in foodstuffs. Nevertheless, the complicated synthesis of nanoprobes hampers their practical applications. Herein, a nanomaterial-independent and fluorescent ELISA for sensitive detection of FQs is developed using the Eu-micelles as signal probe. Non-nanostructured Eu-micelles with high quantum yield and stability are facilely synthesized through the assembly of Eu3+ and ligands. Alkaline phosphatase catalyzes hydrolysis of 4-nitrophenyl phosphate to 4-nitrophenol. The fluorescent Eu-micelles can be readily quenched by 4-nitrophenol via static quenching. The signal generation mechanism integrates well with conventional ELISA systems. The established fluorescent ELISA achieves sensitive detection of FQs with a limit of detection of 0.03 μg/kg. The validation results from LC-MS show that the fluorescent ELISA exhibits good accuracy and recoveries. Our study presents a nanomaterial-independent strategy for developing the rapid immunoassay for FQs, which holds good promise for practical applications.

Rotating magnetic field delays human umbilical vein endothelial cell aging and prolongs the lifespan of Caenorhabditis elegans

The biological effects of magnetic fields are a research hotspot in the field of biomedical engineering. In this study, we further investigated the effects of a rotating magnetic field (RMF; 0.2 T, 4 Hz) on the growth of human umbilical vein endothelial cells (HUVECs) and Caenorhabditis elegans. The results showed that RMF exposure prolonged the lifespan of C. elegans and slowed the aging of HUVECs. RMF treatment of HUVECs showed that activation of adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) was associated with decreased mitochondrial membrane potential (MMP) due to increased intracellular Ca2+ concentrations induced by endoplasmic reticulum stress in anti-aging mechanisms. RMF also promoted the health status of C. elegans by improving activity, reducing age-related pigment accumulation, delaying Aβ-induced paralysis and increasing resistance to heat and oxidative stress. The prolonged lifespan of C. elegans was associated with decreased levels of daf-16 which related to the insulin/insulin-like growth factor signaling pathway (IIS) activity and reactive oxygen species (ROS), whereas the heat shock transcription factor-1 (hsf-1) pathway was not involved. Moreover, the level of autophagy was increased after RMF treatment. These findings expand our understanding of the potential mechanisms by which RMF treatment prolongs lifespan.