Fabrication and evaluation of aptamer-conjugated paclitaxel-loaded magnetic nanoparticles for targeted therapy on breast cancer cells

Targeted drug delivery vehicles make it possible to deliver anti-cancer drugs to the cells or tissues of interest. Aptamers are peptide or oligonucleotide molecules that can serve as targeting elements of drug carriers. In the current study, we evaluated the capacity of an aptamer-based drug carrier to deliver Paclitaxel (PTX) to cancer cells. After being synthesized, SPIONs@PTX-SYL3C aptamer was characterized using different methods, including differential light scattering (DLS), infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), X-ray diffraction (XRD), Thermal gravimetric analysis (TGA), and vibrating sample magnetometer (VSM). Encapsulation efficiency (EE) and loading efficiency (LE) were also evaluated. The carrier was applied on 4T1, MCF 7, and MCF-10A breast cell lines to evaluate its drug delivery potency and specificity. EE and LE were calculated to be 77.6 and 7.76, respectively. MTT results revealed that aptameric SPIONs@PTX was more toxic than non-aptameric SPIONs@PTX. Flowcytometry analysis and DAPI staining confirmed that SPIONs@PTX-Aptamer had higher cell internalization rate when compared to non-targeted SPIONs@PTX. Our results indicate that aptamer-conjugated SPIONs@PTX has a good capacity in recognizing its target cells and inhibiting their growth and division. © 2021, The Author(s), under exclusive licence to Springer Nature B.V. part of Springer Nature

Ultrasensitive aflatoxin B1 assay based on FRET from aptamer labelled fluorescent polymer dots to silver nanoparticles labeled with complementary DNA

The authors describe a new method for the selective detection of aflatoxin B1 (AFB1) by an off-on signaling procedure in a fluorescence resonance energy transfer (FRET)-based nanobioprobe. An amino-modified aptamer against AFB1 was conjugated to fluorescent polymer dots, containing poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-thiadiazole)] as the fluorophore. Complementary DNA (cDNA) was conjugated to silver nanoparticles (cDNA-AgNPs) which act as FRET acceptors. Mixed in solution, in the absence of AFB1, the aptamer and its cDNA hybridize to form (aptamer-cDNA). This brings the polymer dots into close proximity of the AgNPs and result in FRET from the donor to the acceptor due to spectral overlap between the emission of the polymer dots and the absorption of the AgNPs. The fluorescence of the polymer dots probe is thereby switched off. However, in the presence of AFB1, the aptamer with high affinity for AFB1 will be released from the cDNA-AgNP aggregate, which results in recovery of fluorescence (“switch on” state). The yellow fluorescence of the polymer dots, best measured at 538 nm, increases linearly in the 5 pg·mL−1 to 1.0 ng·mL−1 AFB1 concentration range, with a 0.3 pg·mL-1 detection limit. The assay was successfully applied to the detection of AFB1 in (spiked) wheat flour, and the results were found to be in satisfactory agreement with those obtained by an enzyme-linked immunosorbent assay. [Figure not available: see fulltext.] © 2017 Springer-Verlag GmbH Austri