Ultrasensitive detection of staphylococcal enterotoxin B using electrochemical nanoprobe based on AgNPs@para-sulfonatocalix[4]arene-functionalized MXene

Staphylococcal enterotoxins as common bacterial toxins can bring about food contamination and lead to severe foodborne illnesses, so facile and sensitive detection of staphylococcal enterotoxins is significant to ensure food safety and protect public health. In this work, an ultrasensitive biosensor for staphylococcal enterotoxin B (SEB) detection is developed based on the novel electrochemical nanoprobe named MXene/AgNPs@pSC4/MB, which is prepared by functionalizing MXene with para-sulfonatocalix[4]arene-decorated silver nanoparticles (AgNPs@pSC4) and electroactive signal molecules methylene blue (MB). The collaborative effect of AgNPs and MXene endows the fabricated electrochemical nanoprobe with excellent conductivity and admirable loading capacity of signal molecules to significantly enhance the response of biosensor, while pSC4 as the robust linker can bridge the nanoprobe and target SEB by binding with multifarious amino acid residues on SEB. With the specific aptamer immobilized on the electrode as the identifying element to capture SEB, the electrochemical nanoprobes MXene/AgNPs@pSC4/MB are anchored to SEB via pSC4, producing remarkably amplified signal output. The proposed electrochemical biosensor facilitates the ultrasensitive detection of SEB with a low detection limit of 1.76 × 10 −7 ng/mL in addition to the merits of facile operation and rapid response. Moreover, benefiting from the high chemical stability and good resistance to fouling and passivation of the electrochemical nanoprobe, the biosensor exhibits long-lasting stability, good accuracy and anti-interference ability in SEB detection. The reliable detectability of the biosensor has also been examined in the analysis of real food samples, demonstrating potential application toward food safety monitoring.