Complex thiolated mannose/quinone film modified on EQCM/Au electrode for recognizing specific carbohydrate–proteins

• Novel thiolated mannose (TM) and hydroquinone functionalised thiophene (HQFT) were used
• Complex TM/quinone functionalised polythiophene (QFPT) thin film was modified on EQCM/Au electrode
• The TM/QFPT film modified EQCM biosensor has specific sensitivity and selectivity to a lectin—ConA.
• The biosensor presents a paralleled determination by using electrochemical and the QCM method
• The linear range ConA is 0.5–17.5 nM by the electrochemical method and 0.5–4.5 nM by the QCM method

A complex thiolated mannose (TM)/quinone functionalised polythiophene (QFPT) thin film was modified on EQCM/Au electrode for recognition of specific carbohydrate–proteins. Different lectins such as those from Sambucus nigra (elder berry), Arachis hypogaea (peanut), Ulex europaeus (gorse, furze), Triticum vulgaris and Concanavalin A (ConA) was used for probes to evaluate bio-sensing performance of the TM/QFPT film. A specific response was observed for ConA from lectins when using the TM/QFPT film as sensing material and employing either elelctrochemical or the QCM method. No response was detected between thiolated mannose and other lectins. The linear relationship between current and ConA concentration is in the range of 0.5–17.5 nM by the elelctrochemical method and the linear relationship between frequency change and ConA concentration is in the range of 0.5–4.5 nM by the QCM method. This shows that the TM/QFPT-modified EQCM biosensor presents a paralleled determination by using electrochemical and the QCM method. The elelctrochemical method of the biosensor can be applicable in a large concentration range and its frequency change can be more precise.