Highly Ordered, Plasmonic Enhanced Inverse Opal Photonic Crystal for Ultrasensitive Detection of Staphylococcal Enterotoxin B.

Although there is considerable interest in self-assembly of ordered, porous "inverse opal" structures for optical, electronic, and chemical applications, uncontrolled defect formation limits the usefulness of such materials. Herein, we develop a highly ordered and plasmonic enhanced sensing inverse opal photonic crystal (IOPC) material. The co-assembly of the colloidal template with the matrix material avoids the need for liquid penetration into the preassembled colloidal crystals and minimizes the associated rupture and inhomogeneity of the resulting IOPC. Au nanoparticles (Au NPs) not only act as a "bridge" between recognition elements (aptamers) and IOPCs, but also can amplify optical signals. Furthermore, the enhancement mechanism of Au NPs is simulated by COMSOL. During the detection process, the optical signal of the sensing Au-Apt IOPC responds to the Staphylococcal enterotoxin B with a concentration ranging from 10-2 to 103 pg mL-1, and the limit of detection is 2.820 fg mL-1. Spiked real sample detection indicates that the as-proposed method possessed good accuracy. The sensing Au-Apt IOPC provides an extensive biosensor platform to detect a variety of toxic and harmful substances through replacing the aptamer by other recognition elements, such as antibodies or receptors.