Adsorption and Covalent Coupling of ATP-Binding DNA Aptamers onto Cellulose
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With the long-term goal of developing paper surfaces that will detect pathogens, we have investigated physical adsorption and covalent coupling as strategies for treating cellulose surfaces with a DNA aptamer that binds ATP. Physical adsorption was reversible and the isotherms fitted the Langmuir equation with an adsorption maximum of 0.105 mg/m2 at high ionic strength (300 mM NaCl, 25 mM Tris-HCl) and only 0.024 mg/m2 in lower ionic strength buffer (25 mM Tris-HCl). Covalent coupling of amine-terminated aptamer with oxidized cellulose film (Schiff base + reduction) gave 25% coupling efficiency while maintaining the aptamer activity which was illustrated by using a known fluorescent aptamer that is capable of ATP detection. Therefore, covalent coupling, without spacer molecules, is a promising approach for supporting biosensing aptamers on cellulose.
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