Herein, a new molecular nanoparticle based on iron(III)-tannic complexes (Fe–TA NPs) is presented. The Fe–TA NPs were simply obtained by mixing the precursors in a buffered solution at room temperature, and they exhibited good physicochemical properties with capability of inducing autophagy in both hepatocellular carcinoma cells (HepG2.2.15) and normal rat hepatocytes (AML12). The Fe–TA NPs were found to induce HepG2.2.15 cell death via autophagic cell death but have no effect on cell viability in AML12 cells. This is possibly due to the much higher uptake of the Fe–TA NPs by the HepG2.2.15 cells via the receptor-mediated endocytosis pathway. As a consequence, enhancement of the T1 MRI contrast was clearly observed in the HepG2.2.15 cells. The results demonstrate that the Fe–TA NPs could provide a new strategy combining diagnostic and therapeutic functions for hepatocellular carcinoma. Additionally, because of their autophagy-inducing properties, they can be applied as autophagy enhancers for prevention and treatment of other diseases.
We report herein the development
of a simple, sensitive colorimetric
magnetic nanoparticle (MNP)–enzyme-based DNA sandwich assay
that is suitable for simultaneous, label-free quantitation of two
DNA targets down to 50 fM level. It can also effectively discriminate
single-nucleotide polymorphisms (SNPs) in genes associated with human
cancers (KRAS codon 12/13 SNPs). This assay uses a pair of specific
DNA probes, one being covalently conjugated to an MNP for target capture
and the other being linked to an enzyme for signal amplification,
to sandwich a DNA target, allowing for convenient magnetic separation
and subsequent efficient enzymatic signal amplification for high sensitivity.
Careful optimization of the MNP surfaces and assay conditions greatly
reduced the background, allowing for sensitive, specific detection
of as little as 5 amol (50 fM in 100 μL) of target DNA. Moreover,
this sensor is robust, it can effectively discriminate cancer-specific
SNPs against the wild-type noncancer target, and it works efficiently
in 10% human serum. Furthermore, this sensor can simultaneously quantitate
two different DNA targets by using two pairs of unique capture- and
signal-DNA probes specific for each target. This general, simple,
and sensitive DNA sensor appears to be well-suited for a wide range
of genetics-based biosensing and diagnostic applications.
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