Rapid detection assay for the molecular imprinting of gossypol using a two-layer PMAA/SiO2 bulk structure with a piezoelectric imprinting sensor

The rapid and sensitive detection of gossypol is important in the food production and medical fields. In the current study, poly(methacrylic acid) (PMAA) was grafted onto the surface of bulk SiO2 by solution polymerization, producing a molecular imprinting polymer (MIP) with a two-layer PMAA/SiO2 bulk structure. A rapid detection assay for gossypol with a surface MIP having a two-layer PMAA/SiO2 bulk structure combined with a piezoelectric imprinting sensor was developed. The morphology of the PMAA/SiO2 bulks was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscope (AFM). MIP functional groups were confirmed by Fourier transform infrared spectrometry (FTIR). Traditional gossypol detection methods, such as ultraviolet (UV) spectrophotometry and chromatographic analyses, were performed as controls. The material characteristics relevant to gossypol detection, such as binding rate, selectivity coefficient, and binding activity index (I), were measured by UV spectrophotometry, chromatographic analysis, and PMAA/SiO2 bulks combined with a piezoelectric imprinting sensor. The TEM, SEM and AFM images provided clear observations of the two-layer PMAA/SiO2 bulk structures with a 40-nm- to 50-nm-thick of PMAA shell; the temple gossypol molecule can be found on the MIP surface. Compared with traditional detection methods, such as UV spectrophotometry and high-performance liquid chromatography (HPLC)-UV, our assay has the advantages of inducing rapid, high-affinity gossypol binding with a binding activity index of 3.85, a selectivity coefficient of 2.791, and a lower detection limit of 6.0 μg L−1, which is 500 times better than that of HPLC-UV. The detection limits (S/N = 3) of the method is ranged of 6–16 μg L−1 and exhibit good linear relationship with the frequency (R2 = 0.9996). Therefore, the proposed assay shows promise for the detection of gossypol and other biomolecule.