Surface Plasmon Resonance Sensor Enhanced By Structured Nanomaterials

Surface Plasmon Resonance（SPR）sensors have the advantages in highly efficient,label-free and real-time measurement.SPR sensors have been widely investiaged in the fields of biomedicine,environmental detection,agriculture and food safety and other fields.Because of the limited sensitivity,the traditional SPR sensors are facing challenges in detection of analytes in low-concentration or with small-molecule（<500Da）.Therefore,improving the sensitivity of the sensor and enhancing the interaction between molecules are the focus of research.Structured nanomaterials are nanomaterials with the characteristics of the structure and morphology.The combination of the structured nanomaterials and SPR sensor can further improve the performance and broaden the detection application.In this paper,the morphological and physical properties of nanodiamonds（NDs）and molybdenum disulfide（MoS₂）nanoflowers were utilized and combined with SPR to achieve enhanced sensitivity and improve the capture efficiency of small molecule analytes.Research work includes optimizing modification conditions,characterizing bulk sensitivity,obtaining the optimal performance sensor,and applying in the Ig G immunoassay and the adsorption and desorption detection of bipolar molecules.The content of this thesis is summarized as follows:（1）SPR sensors enhanced by MoS₂ nanoflowers.First of all,changing thedifferent modification times of MoS₂ nanoflowers to obtain the best performance of the SPR sensor,the refractive index sensitivity increased from2014 nm/RIU to 2533 nm/RIU and the optimal sensitivity increase was 26%.Thanks to the strong negative charge and petal-like morphology of the MoS₂nanoflower on the sensing surface,the MoS₂ nanoflower-enhanced SPR sensor sensors were applied to the adsorption and desorption experiments of the Rhodamine B and the polar amino acid molecule lysine,and the desorption rates were 96.4%and 96.1%,respectively.（2）SPR sensors enhanced by nanodiamonds.The angle of incidence was reducedand nanodiamonds were modified to increase the sensitivity from 9773nm/RIU to 10682 nm/RIU,obtaining increase of 10%and applied it to the immunoassay of mouse Ig G.The sensitivity was significantly increased from0.07 nm/（μg/m L）to 0.11 nm/（μg/m L）,obtaining increase of 57%,and the detection limit（LOD）was decreased from 0.071μg/m L to 0.036μg/m L.（3）SPR sensors enhanced by MoS₂ nanoflower combined with nanodiamond.First,a layer of MoS₂ nanoflowers were modified,then changed the number of modifications of nanodiamonds to optimize the sensor under the best sensitivity.The best sensitivity was increased from 9658 nm/RIU to 12438nm/RIU,obtaining an increase of 29%,and then applied to the immunoassay of mouse Ig G（5-200μg/m L）.The sensitivity was significantly improved from0.08 nm/（μg/m L）to 0.16 nm/（μg/m L）,gaining an increase of 100%,and the detection limit LOD was decreased from 0.069μg/m L to 0.024μg/m L.The work in this paper shows that the multi-faceted petal-like shape and the rich negative charge peaks of the MoS₂ nanoflowers can effectively enhance the SPR sensor bulk sensitivity and achieve high desorption rate when applied to the adsorption and desorption of bipolar molecules（molecular weight from 146 to 479 Da）.Because of good biocompatibility of nanodiamond can effectively improve the SPR sensor sensitivity when applied to mouse Ig G immunoassay（5-200μg/m L）;The combination of the two materials can increase the bulk sensitivity,greatly improving the sensitivity and decreasing the detection limit（LOD）in immunological detection,which can effectively solve the shortcomings of SPR in detecting low concentration and small molecules.