Ultrasensitive detection of cancer cells and glycan expression profiling based on a multivalent recognition and alkaline phosphatase-responsive electrogenerated chemiluminescence biosensor.

A multivalent recognition and alkaline phosphatase (ALP)-responsive electrogenerated chemiluminescence (ECL) biosensor for cancer cell detection and in situ evaluation of cell surface glycan expression was developed on a poly(amidoamine) (PAMAM) dendrimer-conjugated, chemically reduced graphene oxide (rGO) electrode interface. In this strategy, the multivalency and high affinity of the cell-targeted aptamers on rGO provided a highly efficient cell recognition platform on the electrode. The ALP and concanavalin A (Con A) coated gold nanoparticles (Au NPs) nanoprobes allowed the ALP enzyme-catalyzed production of phenols that inhibited the ECL reaction of Ru(bpy)3(2+) on the rGO electrode interface, affording fast and highly sensitive ECL cytosensing and cell surface glycan evaluation. Combining the multivalent aptamer interface and ALP nanoprobes, the ECL cytosensor showed a detection limit of 38 CCRF-CEM cells per mL in human serum samples, broad dynamic range and excellent selectivity. In addition, the proposed biosensor provided a valuable insight into dynamic profiling of the expression of different glycans on cell surfaces, based on the carbohydrates recognized by lectins applied to the nanoprobes. This biosensor exhibits great promise in clinical diagnosis and drug screening.