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(searched for: doi:10.3390/s19235111)
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A. Antonyan, Z. Movsesyan, M. Parsadanyan,
Russian Journal of Biological Physics and Chemisrty, Volume 7, pp 251-255; https://doi.org/10.29039/rusjbpc.2022.0510

Abstract:
Interaction of dye-intercalator methylene blue (MB) with single-stranded (ss-) polynucleotides poly(rA), poly(rU) and double-stranded poly(rA)-poly(rU) has been studied by the method of absorption spectroscopy at various concentration ratios ligand/phosphate (concentration of ss-polynucleotides by phosphate residue). It was revealed that in the absorption layer of methylene blue, in the wavelength change interval 500≤λ≤750 nm, the absorption spectra of the complexes MB-ss-poly(rA) decrease more sharply, as compared to MB spectrum, along with polynucleotide concentration enhancement in the solution. It was also revealed that the absorption spectra of the complexes MB-ss-poly(rU) decrease moderately at the increase of this polynucleotide concentration in the solution. In the spectra of the complexes MB-ss-poly(rU) a pseudo-isosbestic point is formed, while in the spectra of the complexes MB-ss-poly(rA) there is no such point. The pseudo-isosbestic point is formed also in the spectra of the complexes MB-poly(rA)-poly(rU). It was also revealed that the absorption spectra of the complexes of MB with ss-poly(rA) and poly(rA)-poly(rU) are shifted to the longer wavelengths by ~5-7 nm, while the shift in the absorption spectra of the complexes MB-ss-poly(rU) composes almost ~2 nm. The absorption spectra changes of the complexes of MB with the mentioned polynucleotides indicate that MB shows higher specificity to poly(rA), as compared to poly(rU) and poly(rA)-poly(rU). The obtained data also indicate that MB binds to poly(rA) and poly(rA)-poly(rU) by intercalation and electrostatic modes, and with ss-poly(rU) – mainly by electrostatic mechanism.
Joyasree Bhattacharjee, Sunanda Mishra,
Published: 19 November 2021
Applied Biochemistry and Biotechnology, Volume 194, pp 4745-4764; https://doi.org/10.1007/s12010-021-03767-7

The publisher has not yet granted permission to display this abstract.
Zi-Yang Zhang, Lin-Xiao Huang, Zhi-Wei Xu, Peng Wang, Yun Lei,
International Journal of Nanomedicine, pp 3497-3508; https://doi.org/10.2147/ijn.s308258

Abstract:
Purpose: The PML/RARα fusion gene as a leukemogenesis plays a significant role in clinical diagnosis of the early stage of acute promyelocytic leukemia (APL). Here, we present an electrochemical biosensor for PML/RARα fusion gene detection using carbon dots functionalized graphene oxide (CDs/GO) nanocomposites modified glassy carbon electrode (CDs/GO/GCE). Materials and Methods: In this work, the CDs/GO nanocomposites are produced through π-π stacking interaction and could be prepared in large quantities by a facile and economical way. The CDs/GO nanocomposites were decorated onto electrode surface to improve the electrochemical activity and as a bio-platform attracted the target deoxyribonucleic acid (DNA) probe simultaneously. Results: The CDs/GO/GCE was fabricated successfully and exhibits high electrochemical activity, good biocompatibility, and strong bioaffinity toward the target DNA sequences, compared with only the pristine CDs on GCE or GO on GCE. The DNA biosensor displays excellent sensing performance for detecting the relevant pathogenic DNA of APL with a detection limit of 83 pM (S/N = 3). Conclusion: According to the several experimental results, we believe that the simple and economical DNA biosensor has the potential to be an effective and powerful tool for detection of pathogenic genes in the clinical diagnosis.
Eda Yuhana Ariffin, Emma Izzati Zakariah, Farah Ruslin, Muhammad Kassim, Bohari M. Yamin, Lee Yook Heng,
Published: 12 April 2021
Scientific Reports, Volume 11, pp 1-14; https://doi.org/10.1038/s41598-021-86939-z

Abstract:
Ferrocene or ferrocenium has been widely studied in the field of organometallic complexes because of its stable thermodynamic, kinetic and redox properties. Novel hexaferrocenium tri[hexa(isothiocyanato)iron(III)]trihydroxonium (HexaFc) complex was the product from the reaction of ferrocene, maleic acid and ammonium thiocyanate and was confirmed by elemental analysis CHNS, FTIR and single crystal X-ray crystallography. In this study, HexaFc was used for the first time as an electroactive indicator for porcine DNA biosensor. The UV–Vis DNA titrations with this compound showed hypochromism and redshift at 250 nm with increasing DNA concentrations. The binding constant (Kb) for HexaFc complex towards CT-DNA (calf-thymus DNA) was 3.1 × 104 M−1, indicated intercalator behaviour of the complex. To test the usefulness of this complex for DNA biosensor application, a porcine DNA biosensor was constructed. The recognition probes were covalently immobilised onto silica nanospheres (SiNSs) via glutaraldehyde linker on a screen-printed electrode (SPE). After intercalation with the HexaFc complex, the response of the biosensor to the complementary porcine DNA was measured using differential pulse voltammetry. The DNA biosensor demonstrated a linear response range to the complementary porcine DNA from 1 × 10−6 to 1 × 10−3 µM (R2 = 0.9642) with a limit detection of 4.83 × 10−8 µM and the response was stable up to 23 days of storage at 4 °C with 86% of its initial response. The results indicated that HexaFc complex is a feasible indicator for the DNA hybridisation without the use of a chemical label for the detection of porcine DNA.
Published: 15 April 2020
by MDPI
Journal: Diagnostics
Abstract:
Methylene blue and proflavine are fluorescent dyes used to stain nucleic acid from the molecular level to the tissue level. Already clinically used for sentinel node mapping, detection of neuroendocrine tumors, methemoglobinemia, septic shock, ifosfamide-induced encephalopathy, and photodynamic inactivation of RNA viruses, the antimicrobial, anti-inflammatory, and antioxidant effect of methylene blue has been demonstrated in different in vitro and in vivo studies. Proflavine was used as a disinfectant and bacteriostatic agent against many gram-positive bacteria, as well as a urinary antiseptic involved in highlighting cell nuclei. At the tissue level, the anti-inflammatory effects of methylene blue protect against pulmonary, renal, cardiac, pancreatic, ischemic-reperfusion lesions, and fevers. First used for their antiseptic and antiviral activity, respectively, methylene blue and proflavine turned out to be excellent dyes for diagnostic and treatment purposes. In vitro and in vivo studies demonstrated that both dyes are efficient as perfusion and tissue tracers and permitted to evaluate the minimal efficient concentration in different species, as well as their pharmacokinetics and toxicity. This review aims to identify the optimal concentrations of methylene blue and proflavine that can be used for in vivo experiments to highlight the vascularization of the skin in the case of a perforasome (both as a tissue tracer and in vascular mapping), as well as their effects on tissues. This review is intended to be a comparative and critical presentation of the possible applications of methylene blue (MB) and proflavine (PRO) in the surgical field, and the relevant biomedical findings from specialized literature to date are discussed as well.
Published: 14 March 2020
Current Opinion in Electrochemistry, Volume 23, pp 36-41; https://doi.org/10.1016/j.coelec.2020.03.003

The publisher has not yet granted permission to display this abstract.
Published: 26 February 2020
by MDPI
Journal: Sensors
Sensors, Volume 20; https://doi.org/10.3390/s20051279

Abstract:
A novel label-free electrochemical DNA biosensor was constructed for the determination of Escherichia coli bacteria in environmental water samples. The aminated DNA probe was immobilized onto hollow silica microspheres (HSMs) functionalized with 3-aminopropyltriethoxysilane and deposited onto a screen-printed electrode (SPE) carbon paste with supported gold nanoparticles (AuNPs). The biosensor was optimized for higher specificity and sensitivity. The label-free E. coli DNA biosensor exhibited a dynamic linear response range of 1 × 10−10 µM to 1 × 10−5 µM (R2 = 0.982), with a limit of detection at 1.95 × 10−15 µM, without a redox mediator. The sensitivity of the developed DNA biosensor was comparable to the non-complementary and single-base mismatched DNA. The DNA biosensor demonstrated a stable response up to 21 days of storage at 4 ℃ and pH 7. The DNA biosensor response was regenerable over three successive regeneration and rehybridization cycles.
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