Recent Approaches in Magnetic Nanoparticle-Based Biosensors of miRNA Detection

In recent years, magnetic nanoparticles (MNPs) have been widely used in many fields due to their advantageous properties, such as biocompatibility, easy modifiability, and high chemical stability. One of these areas is the detection of cancer. It is essential to use existing biomarkers, such as microRNAs (miRNAs), for the early diagnosis of this disease. miRNAs are challenging to distinguish and detect in biological samples because they are small, circulating molecules. It is necessary to use more sensitive and feature-rich systems. Thanks to their large surface areas and magnetic moments, MNPs allow easy separation of miRNA at low concentrations from complex samples (urine and blood) and rapid and specific detection in biosensing systems. Here, we discussed the synthesis and characterization methods of MNPs, their stabilization, and MNP-based biosensors in terms of miRNA detection. We considered the challenges and prospects of these biosensor systems in evaluating the development stages, sensitivity, and selectivity

Synthetic antibodies for methamphetamine analysis: Design of high affinity aptamers and their use in electrochemical biosensors

An aptamer-based electrochemical biosensor was designed and fabricated for methamphetamine (METH) anal-ysis. Several aptamer sequences developed by the GO-SELEX method were immobilized onto gold electrodes (GE) via gold-thiol affinity. Surface characterizations were performed by electrochemical methods including cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectrometry (EIS). GE/Apta-4/METH aptasensor was selected for further studies since the best results were obtained with the Apta-4 sequence in terms of analytical parameters. Accordingly, it exhibited good selectivity for METH analysis with a wide linear range of 0.1-50 ng/mL and a low limit of detection (LOD) which was found to be 0.467 ng/mL. The proposed aptasensor platform displayed good selectivity for the detection of METH in synthetic urine samples spiked with METH.This work was supported by the Republic of Turkey, Ministry of Development (Project Grant No: 2016 K121190) and partially by Ege University Scienti fi c Research Projects Coordination Unit (Project Grant No: 18 -FEN -006) . We thank Ege University Central Research Testing and Analysis Laboratory Research and Application Center (EGE-MATAL) for ITC measurements.Republic of Turkey, Ministry of Development [2016 K121190]; Ege University Scienti fi c Research Projects Coordination Unit [18 -FEN -006

Post-Vaccination Detection of SARS-CoV-2 Antibody Response with Magnetic Nanoparticle-Based Electrochemical Biosensor System

Here, we report magnetic nanoparticle-based biosensor platforms for the rapid detection of SARS-CoV-2 antibody responses in human serum. The use of the proposed system enabled the detection of anti-SARS-CoV-2 spike (S) and nucleocapsid (N) proteins at a concentration of ng/mL in both buffer and real serum samples. In particular, the protocol, which is considered an indicator of innate immunity after vaccination or post-infection, could be useful for the evaluation of antibody response. We included a total of 48 volunteers who either had COVID-19 but were not vaccinated or who had COVID-19 and were vaccinated with CoronoVac or Biontech. Briefly, in this study, which was planned as a cohort, serum samples were examined 3, 6, and 12 months from the time the volunteers’ showed symptoms of COVID-19 with respect to antibody response in the proposed system. Anti-S Ab and anti-N Ab were detected with a limit of detection of 0.98 and 0.89 ng/mL, respectively. These data were confirmed with the corresponding commercial an electrochemiluminescence immunoassay (ECLIA) assays. Compared with ECLIA, more stable data were obtained, especially for samples collected over 6 months. After this period, a drop in the antibody responses was observed. Our findings showed that it could be a useful platform for exploring the dynamics of the immune response, and the proposed system has translational use potential for the clinic. In conclusion, the MNP-based biosensor platform proposed in this study, together with its counterparts in previous studies, is a candidate for determining natural immunity and post-vaccination antibody response, as well as reducing the workload of medical personnel and paving the way for screening studies on vaccine efficacy

Dye-Loaded Polymersome-Based Lateral Flow Assay: Rational Design of a COVID-19 Testing Platform by Repurposing SARS-CoV-2 Antibody Cocktail and Antigens Obtained from Positive Human Samples

The global pandemic of COVID-19 continues to be an important threat, especially with the fast transmission rate observed after the discovery of novel mutations. In this perspective, prompt diagnosis requires massive economical and human resources to mitigate the disease. The current study proposes a rational design of a colorimetric lateral flow immunoassay (LFA) based on the repurposing of human samples to produce COVID-19-specific antigens and antibodies in combination with a novel dye-loaded polymersome for naked-eye detection. A group of 121 human samples (61 serums and 60 nasal swabs) were obtained and analyzed by RT-PCR and ELISA. Pooled samples were used to purify antibodies using affinity chromatography, while antigens were purified via magnetic nanopArticles-based affinity. The purified proteins were confirmed for their specificity to COVID-19 via commercial LFA, ELISA, and electrochemical tests in addition to sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. Polymersomes were prepared using methoxy polyethylene glycol-b-polycaprolactone (mPEG-b-PCL) diblock copolymers and loaded with a Coomassie Blue dye. The polymersomes were then functionalized with the purified antibodies and applied for the preparation of two types of LFA (antigen test and antibody test). Overall, the proposed diagnostic tests demonstrated 93 and 92.2% sensitivity for antigen and antibody tests, respectively. The repeatability (92-94%) and reproducibility (96-98%) of the tests highlight the potential of the proposed LFA. The LFA test was also analyzed for stability, and after 4 weeks, 91-97% correct diagnosis was observed. The current LFA platform is a valuable assay that has great economical and analytical potential for widespread applications.We send our acknowledgment to the staff of EGE University Hospital who are on the front line fighting against the COVID19 pandemic. FTIR and SEM analyses were performed at EGE MATAL (Ege University/Izmir). EGE University, Research Foundation was acknowledged for the financial support (TOA2020-21862). Republic of Turkey, Ministry of Development provided the support for the infrastructure of EGE MATAL (Ege University/Izmir) via 2010K120810/2020K12150700 and 2016K121190 grants.EGE University, Research Foundation [TOA2020-21862]; Republic of Turkey, Ministry of Development [2010K120810/2020K12150700, 2016K121190

Breath as the mirror of our body is the answer really blowing in the wind? Recent technologies in exhaled breath analysis systems as non-invasive sensing platforms

Health care monitoring is an enormous field of research that has great potential to solve many problems in human life. In recent years, non-invasive health monitoring has become a prerequisite for early diagnosis of various diseases such as lung cancer, oxidative stress, diabetes, to enable the prompt treatment and screening of crucial chemicals. Although analyzing of exhaled breath has been correlated with advanced analytical techniques such as gas chromatography and infrared spectroscopy, breath analyzing biosensing systems offer a cost-effective, sensitive platform for a straightforward analysis. However, current non-invasive sensing strategies have been lacking in practicality in terms of the design and usage, on-site ability and accessibility. This review will critically discuss current commercialized breath analyzers, the recent achievements for the use of the detection towards chemical and biological substances from exhaled breath as non-invasive sensing systems including challenges/drawbacks by addressing the practical applications and concerns in the field. The different fabrication strategies, methodology of detection techniques involved in the development of the breath analyzing systems will be overviewed and discussed along with the future opportunities for possible point of care applications with smartphone integration in this review. The scientific and technological challenges in the field are discussed in the conclusion. (C) 2021 Elsevier B.V. All rights reserved.Ege University, Turkey; King Abdullah University of Science and Technology (KAUST), Saudi ArabiaThe authors would like to thank Dr. Abdellatif Ait Lachen and Dr Veerappan Mani for their suggestions and comments. In addition, the authors would like to express their acknowledgments to the financial support of funding from Ege University, Turkey and King Abdullah University of Science and Technology (KAUST), Saudi Arabia

Magnetic Nanoparticle-Based Electrochemical Sensing Platform Using Ferrocene-Labelled Peptide Nucleic Acid for the Early Diagnosis of Colorectal Cancer

Diagnostic biomarkers based on epigenetic changes such as DNA methylation are promising tools for early cancer diagnosis. However, there are significant difficulties in directly and specifically detecting methylated DNA regions. Here, we report an electrochemical sensing system based on magnetic nanoparticles that enable a quantitative and selective analysis of the methylated septin9 (mSEPT9) gene, which is considered a diagnostic marker in early stage colorectal cancer (CRC). Methylation levels of SEPT9 in CRC samples were successfully followed by the selective recognition ability of a related peptide nucleic acid (PNA) after hybridization with DNA fragments in human patients’ serums and plasma (n = 10). Moreover, this system was also adapted into a point-of-care (POC) device for a one-step detection platform. The detection of mSEPT9 demonstrated a limit of detection (LOD) value of 0.37% and interference-free measurement in the presence of branched-chain amino acid transaminase 1 (BCAT1) and SRY box transcription factor 21 antisense divergent transcript 1 (SOX21-AS1). The currently proposed functional platform has substantial prospects in translational applications of early CRC detection