Electrochemical Sandwich-Type Aptasensor Based on the Multifunctional Catechol-Loaded Au/MIL-53(Fe) for Detection of Cardiac Troponin I

Accurate detection of irreversible acute myocardial infarction (AMI) is always a challenge in clinical emergencies, and its early diagnosis can increase the patient’s chance of surviving. Herein, an electrochemical aptasensor with excellent sensitivity and accuracy was developed for the detection of cardiac troponin I (cTnI). This aptasensor is prepared using sandwiching the cTnI biomarker between the magnetic nanoparticles/Tro6 aptamer (MNPs/Tro6) and multifunctional catechol-(CC)-loaded Tro4/Au/MIL-53(Fe)-based nanocomposite [Tro4/CC/Au/MIL-53(Fe)]. The CC/Au/MIL-53(Fe) provides high electrocatalysis toward electro-oxidation of hydrazine, numerous active sites as the signal amplifier and Tro4 aptamer carrier, on the one hand, and the MNPs, which provide the high complex media’s signal-to-noise ratio (S/N), on the other hand. Analysis of the electrochemical impedance spectroscopy data revealed that the double layer capacitance (surface roughness effect) contributed to the CC/Au/MIL-53(Fe)’s increased activity in part but that the intrinsic activity was mostly responsible (synergistic effect). The optimized sandwich-type aptasensor by a face-centered central composite design allows for the detection of cTnI (0.5 pg mL–1) with a broad dynamic range (2 pg mL–1 to 150 ng mL–1), addressing the clinical necessity of AMI diagnosis as well as exceptional selectivity among different biomarkers. The recommended method was effectively used to assess cTnI in AMI patient plasma, above 90% clinical sensitivity, highlighting the capability of the platform for bioanalysis in real-world samples

Aptamer-conjugated magnetic nanoparticles as targeted magnetic resonance imaging contrast agent for breast cancer

Early detection of breast cancer is the most effective way to improve the survival rate in women. Magnetic resonance imaging (MRI) offers high spatial resolution and good anatomic details, and its lower sensitivity can be improved by using targeted molecular imaging. In this study, AS1411 aptamer was conjugated to Fe3O4@Au nanoparticles for specific targeting of mouse mammary carcinoma (4T1) cells that overexpress nucleolin. In vitro cytotoxicity of aptamer-conjugated nanoparticles was assessed on 4T1 and HFFF-PI6 (control) cells. The ability of the synthesized nanoprobe to target specifically the nucleolin overexpressed cells was assessed with the MRI technique. Results show that the synthesized nanoprobe produced strongly darkened T2-weighted magnetic resonance (MR) images with 4T1 cells, whereas the MR images of HFFF-PI6 cells incubated with the nanoprobe are brighter, showing small changes compared to water. The results demonstrate that in a Fe concentration of 45 μg/mL, the nanoprobe reduced by 90% MR image intensity in 4T1 cells compared with the 27% reduction in HFFF-PI6 cells. Analysis of MR signal intensity showed statistically significant signal intensity difference between 4T1 and HFFF-PI6 cells treated with the nanoprobe. MRI experiments demonstrate the high potential of the synthesized nanoprobe as a specific MRI contrast agent for detection of nucleolin-expressing breast cancer cells

Wireless Electrochemiluminescence Bipolar Electrode Array for Visualized Genotyping of Single Nucleotide Polymorphism

The development of simple, inexpensive, hand-held, user-friendly biosensor for high throughput and multiplexed genotyping of various single nucleotide polymorphisms (SNPs) in a single run experiment by a nonspecialist user is the main challenge in the analysis of DNA. Visualizing the signal and possibility to monitor SNPs by a digital camera opens a new horizon for the routine applications. In the present manuscript, a novel wireless electrochemiluminescence (ECL) DNA array is introduced for the visualized genotyping of different SNPs on the basis of ECL of luminol/hydrogen peroxide system on a bipolar electrode (BPE) array platform. After modification of anodic poles of the array with the DNA probe and its hybridization with the targets, genotyping of various SNPs is carried out by exposing the array to different monobase modified luminol-platinum nanoparticles (M-L-PtNPs). Upon the hybridization of M-L-PtNPs to mismatch sites, the ECL of luminol is followed using a photomultiplier tube (PMT) or digital camera and the images are analyzed by ImageJ software. This biosensor can detect even thermodynamically stable SNP (G–T mismatches) in the range of 2–600 pM. Also, by combining the advantages of BPE and the high visual sensitivity of ECL, it could be easily expected to achieve sensitive screening of different SNPs. The present biosensor demonstrates the capability for the discrimination between PCR products of normal, heterozygous, and homozygous beta thalassemia genetic disorders