Silver decahedral nanoparticles empowered SPR imaging-SELEX for high throughput screening of aptamers with real-time assessment

A highly efficient method for aptamer screening with real-time monitoring of the SELEX process was described by silver decahedra nanoparticles (Ag-10-NPs) enhanced surface plasmon resonance imaging (SPRI). A microarray chip was developed by immobilization of target protein (Lactoferrin (Lac)) and control proteins (alpha-lactalbumin (alpha), beta-lactoglobulin (beta), casein, and bovine serum albumin (BSA)) on the biochip surface. Ag-10-NPs were conjugated with an ssDNA library (Hb) (Ag-10-NPs-library) that consisted of a central 40 nt randomized sequence and a 20 nt fixed primer sequence. Introduction of the Ag-10-NPs-library to the SPRI flow channels drastically increased the sensitivity of SPRI signal for real-time monitoring of SELEX. The work allows rapid screening of potential targets, and yields nine aptamers with high affinity (nanomolar range) for Lac after only six-rounds of selection. The aptamer Lac 13.26 was then further tested by SPRI, and the results demonstrated that the aptamer had the capacity to be ultra-sensitive for specific detection of Lac. The novel SPRI-SELEX method demonstrated here showed many advantages of real-time evaluation, high throughput, and high efficiency.