SPR Quantitative Analysis Of Direct Detection Of Atrazine Traces On Au-nanoparicles

In this paper, a new approach that combines two-channel SPR sensor technology with Au nanoparticles (AuNPs) is developed for direct detection of atrazine in maize. The amplification performance of three different size AuNPs (17.26 nm,24.13 nm, and 30.35nm) as the sensor layer were compared for direct detection of atrazine based on SPR biosensor. The best amplification performance was obtained for AuNPs with diameter of 30.35 nm. The selectivity, real sample detect and spiked recovery test for atrazine detection were performed using the 30.35 nm AuNPs. The SPR direct detection (without AuNPs) and liquid chromatography tandem mass spectrometry (LC-MS/MS, GB/T23816-2009) were respectively conducted for detection of atrazine in maize to demonstrate the amplification effect of AuNPs with accuracy, repeatability and sensitivity. The presented immunosensor showed low detection limit, good reproducibility, high selectivity and accuracy. The main study contents were summarized as follows:1. AuNPs were prepared by reducing HAuCl4 with trisodium citrate. Monodispersed spherical AuNPs with different sizes(30.35±2.05nm、24.13±3.78nm、17.26±0.14nm) were synthesized through controlling the molar ratio of HAuCl4 to sodium citrate. The resulting AuNPs was characterized by Transmission electron microscope (TEM) and ultraviolet-visible spectrum (UV). The morphology of the resulting AuNPs were uniform, homodisperse and have good stability.2. SPR direct format for direct detection of atrazine:The anti-atrazine was immobilized on the chip surface by the standard amine-coupling procedure, then different concentration of atrazine were directly detected. A good linear relationship was obtained between SPR signals and atrazine concentrations from 3.9 ng/mL to 31.3 ng/mL. The regression equation was Y=1.429+0.175X, R2=0.9205, the range of relative standard deviation (RSD) range was 3.98%-6.9%. Atrazine concentrations as low as 3.9 ng/mL can be readily measured3. AuNPs enhanced SPR biosensor response to directly detect atrazine:The amplification performance of three different size AuNPs as the SPR sensor layer were compared for direct detection of atrazine. After, the anti-atrzine were immobilized on the surface of three different size AuNPs, different concentrazine of atrazine were directly detected. The best sensitivity was obtained for AuNPs with diameter of 30.35nm. The selectivity experiment, real sample test and the recovery experiment were performed by optimized AuNPs size. A good linear relationship was obtained between SPR signals and atrazine concentrations from 0.5 ng/mL-7.8 ng/mL. The equation of liner regression of this method was Y=1.280+0.701X (R2=0.9920), the lowest detection concentration was 0.5 ng/mL, the limit of detection (LOD) was 0.112ng/m (S/N=3), the range of RSD was 1.73～10.78%. It was decreased nearly eight times than the reference sensor (2) for the minimum detectable concentration. The range of the recovery was 87.1%-95.2%, the range of RSD was 1.64%～2.26%. The detection result of the SPR biosensor was compared with LC-MC/MC method (GB/T23816-2009 for atrazine detection in maize). The result were in agreement. The maize were do not contain atrazine.