Quartz crystal microbalance detection of protein amplified by nicked circling, rolling circle amplification and biocatalytic precipitation

• DNA nicked circling and rolling circle amplification strategies were used in this QCM assay.
• Biocatalyzed precipitation cause further signal amplification.
• This aptasensor can be used to detect lysozyme sensitively with high selectivity.

A novel quartz crystal microbalance (QCM) assay was described for sensitive detection of protein. Lysozyme was used as a model of protein. To enhance the sensitivity of this QCM biosensor, biocatalytic precipitation (BCP) reaction combined with strand-scission cycle and rolling circle amplification (RCA) were applied together for the first time. As a result of the multi-signal amplification in this aptasensor, the detection limit for lysozyme was down to 0.3 fM. What is more, this amplified QCM biosensor also showed good selectivity and practical usage in human serum.