Development of a homogenous assay based on fluorescent imprinted nanoparticles for analysis of nitroaromatic compounds

Herein we describe the development of a homogeneous assay for the detection of 4-nitroaniline (4-NA) and 2,4-dinitroaniline (2,4-diNA). This assay relies on fluorescent molecularly imprinted nanoparticles (nanoMIPs) which, upon interaction with the target analytes, generate a reduction in fluorescence emission intensity (quenching). This is due to a responsive fluorescent monomer (N-2-propenyl-(5-dimethylamino)-1-naphthalene sulphonamide) employed in the manufacture of the nanoMIPs which, by virtue of the imprinting process, is capable of selective interaction with the target analyte, thus giving rise to a quenching effect. Selectivity experiments showed excellent recognition properties toward the target molecule. Under optimal conditions, the fluorescence intensity of these nanoMIPs decreased as the concentration of the imprinted analyte increased from 10 nM to 2.71 μM. A linear relation between the negative logarithm of 4-NA or 2,4-diNA concentrations and the fluorescence intensity for both nanosystems was found (R2 = 0.991 and R2 = 0.9895), with excellent sensitivity (limit of detection (LOD) = 7 and 6 nM, respectively). Furthermore, both nanosystems have been successfully applied for detection of 4-NA or 2,4-diNA in tap water, with recoveries between 90% to 100.6% and 92% to 100.3%, respectively. Thanks to the versatility of the imprinting process, this nanosystem holds the potential for further development of several optical sensors for many other compounds. [Figure not available: see fulltext.].</p

Detecting and targeting senescent cells using molecularly imprinted nanoparticles

The progressive accumulation of senescent cells in tissues in response to damage importantly contributes to pathophysiological conditions such as fibrosis, diabetes, cancer, Alzheimer's and ageing. Consistent with this, eliminating senescent cells prolongs the lifespan and healthspan in animals and ameliorates certain diseases. Detecting and clearing senescent cells from human tissues could therefore have a significant diagnostic and prognostic impact. However, identifying senescent cells in vivo has proven to be complex. To address this, we characterized and validated a panel of novel membrane markers of senescence. Here, we show the application of molecularly imprinted nanoparticles (nanoMIPs) against an extracellular epitope of one of these markers, B2M, to detect senescent cells in vitro and in vivo. We show that nanoMIPs do not elicit toxic responses in the cells or in mice and successfully recognize old animals, which have a higher proportion of senescent cells in their organs. Importantly, nanoMIPs loaded with drugs can specifically kill senescent cells. Our results provide a proof-of-principle assessment of specific and safe nanotechnology-based approaches for senescent cell detection and clearance with potential clinical relevance