Possible sensor applications of selected DNA–surfactant complexes

Abstract

Although much research has been performed on DNA complexes carrying long alkyl chains (C10, C16, and C18), there is no information about physicochemical characterization of synthesized composites with allyl imidazole-based ionic liquids and quaternary ammonium salts with n-butyl chains. Here, complexes were synthesized by ion-exchange reactions between sonicated DNA and three ionic liquids (ILs) formed from two imidazole-based compounds, 1-allyl-3-methylimidazolium bromide (Amim) or 1-butyl-3-methylimidazolium bromide (Bmim), and from the quaternary ammonium salt tetra-n-butylammonium bromide (TBAB). Signals in UV-Vis, IR, and CD spectra indicating inclusion of small molecules into the DNA structure confirmed the formation of DNA complexes. Both IR and CD spectra indicated that the B-form conformation of the DNA did not change after the formation of the complexes. Similarly, X-ray diffraction patterns revealed that the formation of IL-DNA complexes did not change the structure of native B-form DNA. Molecular weight (M w) and radii of gyration (R g) values of IL-DNA complex chains, established by high-performance size exclusion chromatography coupled with multiangle-laser light-scattering with a differential refractive index detector, were significantly lower than those values found for native DNA molecules due to DNA fragmentation by sonication during complex formation and the direct effects of the IL on the DNA. Scanning electron microscopy images indicate the formation of nanofibres in DNA-Amim and DNA-Bmim complexes, whereas the formation of nanowires was found in samples of DNA-TBAB complexes. Changes in optical properties confirmed by UV and photoluminescence make DNA-IL complexes potential candidates for biosensor application.

An electrochemical membrane-based aptasensor for detection of severe acute respiratory syndrome coronavirus-2 receptor-binding domain

“…As shown, an absorption band at 3192 cm −1 due to the –OH stretching, and two absorption bands at 1150 cm −1 , 926 cm −1 due to the –Al-O stretching (a) were recorded. After the immobilization of aptamer (b), a band at 3390 cm −1 due to –NH 2 , a band at 2918 cm −1 , a band at 1119 cm −1 due to –PO 2 − , two bands at 1150 cm −1 and 926 cm −1 due to the –Al-O-Si stretching, a band at 1538 cm −1 due to the –C = O stretching, a band at 1313 cm −1 due to the –C-N stretching of amide III, stretching a band at 1277 cm −1 due to the –PO 2 − stretching, a band at 1047 cm −1 due to the –C-O-P bending, an absorption band at 792 cm −1 due to the = C-H bending appeared, indicating the aptamer probe was immobilized inside the membrane [55] .

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An Electrochemical Impedance Spectroscopy-Based Aptasensor for the Determination of SARS-CoV-2-RBD Using a Carbon Nanofiber–Gold Nanocomposite Modified Screen-Printed Electrode

“…An absorption band at 3013 cm −1 due to the -NH2 stretching was observed. Additionally, an absorption band at 2622 cm −1 due to -CH stretching, an absorption band at 1609 cm −1 due to -C=C stretching, an absorption band at 1480 cm −1 due to in-plane vibration of nucleotide bases, an absorption band at 1333 cm −1 due to the -C-N stretching of nucleotide bases, an absorption band at 1221 cm −1 due to the -PO2 − stretching, an absorption band at 1163 cm −1 due to the -C-O stretching of aliphatic ether in deoxyribose, an absorption band at 965 cm −1 due to PO2 − bending, an absorption band at 890 cm −1 due to the deoxyribose ring vibration, and an absorption band at 710 cm −1 due to sugar-phosphate vibration are clearly seen [38]. The ATR results indicated that the aptamer probes were immobilized on the surface of the electrode.…”

Putting DNA to Work as Generic Polymeric Materials

“…The Yam group created DNA hydrogels by the electrostatic attraction between phosphate groups and platinum ions [31] . As another positively charged molecule, cationic surfactants not only interact with phosphate groups to form hybrid hydrogels but also introduce their self‐assembly behaviors into the gelation process, leading to hydrogels with specific morphology such as spheres [32, 33] …”