An ultrasensitive label-free biosensor based on aptamer functionalized two-dimensional photonic crystal for kanamycin detection in milk.

A novel photonic crystal aptamer biosensor SiO2-Au-ssDNA two-dimensional photonic crystal (2D PC), allowing label-free and highly sensitive to kanamycin (KANA), is successfully manufactured. This 2D PC biosensor was prepared via a needle tip flow method, using electrostatic adsorption to introduce negatively charged gold nanoparticles (Au NPs) into the 2D PC, combined with sulfhydryl-modified ssDNA for the rapid measurement. Benefiting from the localized surface plasmon resonance effect of Au NPs and optical response capability of PC, the biosensor has an excellent performance on quantitative analysis of KANA ranging from 5 pg∙mL-1 to 5 μg∙mL-1, with a limit of detection of 1.10 pg∙mL-1. The recovery of KANA is between 97 % and 110 % in the milk samples with relative standard deviation less than 4.8 %, which revealing that the 2D PC biosensor has the excellent performance on the KANA detection in complex conditions.