Abstract
With the increasing application of antimicrobial peptides (AMPs) to replace antibiotics in medicine, food and agriculture, it is highly desired to develop a fast, reliable, and convenient strategy for sensitive detection of AMPs. Herein, a novel electrochemical (EC) and electrochemiluminescence (ECL) dual-modality sensing platform was developed based on probe encapsulated liposomes and nanochannel array modified electrodes, which enables sensitive determination of nisin in food samples. The bifunctional probe with both EC and ECL signals, tris(2,2-bipyridyl) dichlororuthenium (II) (Ru(bpy)(3) (2+)), was chosen to be easily encapsulated in liposomes (Ru(bpy)(3) (2+)@liposome). Based on the unique sterilization mechanism that AMPs can disrupt cell membranes, Ru(bpy)(3) (2+)@liposome can be destroyed by nisin and release a large number of Ru(bpy)(3) (2+) probes. Vertically-ordered mesoporous silica-nanochannel film (VMSF) modified ITO electrodes (VMSF/ITO) prepared by electrochemically assisted self-assembly (EASA) method were applied as the sensing electrode. Due to the efficient enrichment of Ru(bpy)(3) (2+) by the negatively charged nanochannel arrays, VMSF/ITO enables detection of the EC/ECL signals of the released Ru(bpy)(3) (2+) probes with ultrahigh sensitivity. In consequence, sensitive dual-modality detection of nisin was achieved by the combination of Ru(bpy)(3) (2+)@liposome and VMSF/ITO. The developed sensing system can realize sensitive determination of nisin in ECL mode in the concentration range of 10 ng/ml to 50 μg/ml with a limit of detection (LOD) of 9.3 ng/ml, or in EC mode from 800 ng/ml to 100 μg/ml with a LOD of 70 ng/ml. Combined with the excellent anti-fouling and anti-interference performance of VMSF, rapid and sensitive detection of nisin in milk or egg white was also achieved by the sensor.