| As one of the three major plant staple foods,wheat has abundant nutritional elements and has been used in a wide range of deeply processed foods.However,wheat,as one of the“Big Eight”allergenic food ingredients,contains a variety of allergenic components.Among them,gluten is the major allergen in wheat,which can induce wheat-dependent exercise-induced anaphylaxis,hives,asthma,etc.Therefore,accurate,efficient,and ultra-sensitive identification and detection of wheat allergens in the context of complex food matrix has important practical significance for ensuring the scientific labeling and sensitization prevention and control of wheat foods.Surface-enhanced Raman scattering（SERS）has a promising future in the field of detection and analysis due to its advantages of high sensitivity and on-site monitoring.Hence,this study aims at the needs of ultra-sensitive trace qualitative detection and rapid and accurate quantitative detection of wheat allergens,combining metal-organic frameworks loaded with silver nanoparticles（Ag NPs/MOF）and Au NR dimers with excellent SERS performance to construct DNA-based sandwich sensor and aptamer-based competitive sensor,respectively,applies them to the sensitive and accurate detection of wheat allergens in processed foods.The main research contents and results are as follows:1.Construction and performance study of SERS biosensor based on DNA-MOFIn this study,Ag NPs/MOF was prepared as a SERS substrate by in situ synthesis,and its synthesis conditions were optimized with a Raman enhancement factor of 1.89×105.Combining the signal amplification function of Ag NPs/MOF and the superiority of SERS,a DNA-based sandwich SERS sensor（Ag NPs/MOF SERS sensor）was constructed for the highly sensitive trace field detection of wheat gluten.Under the optimized detection conditions,the Ag NPs/MOF SERS sensor was able to detect t DNA in the range of 1×10-15～2×10-6M.The standard linear equation was Y=745.57 lg X+12475.86,with a correlation coefficient was 0.9959,and the limit of detection（LOD）was 1.16×10-16M（S/N=3）.The spiked recoveries of wheat allergen in blank samples ranged from 96.34%to 104.44%,and the intra-batch and inter-batch precision ranged from 1.80%to 3.18%and 1.24%to 4.29%,respectively.The constructed Ag NPs/MOF SERS sensor has good specificity and storage stability,which provides a new idea to achieve ultra-sensitive,trace,and in-site detection of allergens in the field of food safety.2.Construction and performance study of SERS biosensor based on aptamer-Au NR dimersIn this study,Au NR dimers was prepared as a SERS substrate by self-assembly technique,and the Raman enhancement factor of the dimers was 2.07×105after optimization of its synthesis condition.Based on the signal amplification function of Au NR dimers and the target recognition function of specific aptamer,a competitive SERS sensor（Au NR dimers SERS sensor）was constructed for the accurate quantitative detection of wheat gluten.The performance study showed that the SERS signal of the Au NR dimers SERS sensor showed a good linear relationship with the gluten content in the detection range of 0.1～20μg/m L,and the standard curve regression equation was Y=-1180.31 lg X+3891.85 with a correlation coefficient of 0.9994,the LOD was 35.06 ng/m L（S/N=3）,and the sensor has high specificity.The spiked recoveries of gluten in blank samples ranged from 89.54%to 108.49%,and the intra-batch and inter-batch precision ranged from 2.47%to 3.15%and 2.39%to 4.01%,respectively,showed good storage stability within 35 days,providing a new technical system for the rapid and accurate quantification of gluten in foods.3.Study on the applicability of SERS sensor in wheat gluten detectionIn this study,we confirmed that the Ag NPs/MOF SERS sensor and the Au NR dimers SERS sensor constructed in this study can achieve accurate identification and detection of wheat gluten in complex food matrices by using q PCR and ELISA,respectively.The results of sample spiking experiments showed that the spiking recoveries of Ag NPs/MOF SERS sensor and Au NR dimers SERS sensor ranged from 92.05%to 107.29%and 98.47%to109.69%,respectively.By detecting wheat gluten in 21 wheat products from five categories of deeply processed foods,confirming that both SERS sensors have a wide range of applicability,and the Ag NPs/MOF SERS sensor being more suitable for ultra-sensitive analysis of trace residual allergens in samples,while the Au NR dimers SERS sensor is suitable for rapid and accurate quantitative detection of allergenic proteins in samples.These SERS sensors provide a new approach to the sensitive and accurate quantification of allergens in complex matrix samples. |
