基于枝角金纳米颗粒的LSPR传感器制备与免疫检测

Fabrication of LSPR Sensors Based on Branched Gold Nanoparticles for Immunoassays

枝角状纳米金结构具备尖锐的边缘和耦合区域的“热点”,可极大增强粒子的周围电场,使纳米粒子具备很强的局域表面等离子共振(LSPR)性能.本文在光纤表面原位制备具有枝角结构的金纳米材料,构建光纤LSPR传感器,并将其应用于免疫检测中.首先在预处理的光纤表面修饰一层聚多巴胺黏附层,再连接金纳米晶种,进一步利用原位还原与银诱导法,合成具有枝角状结构的金纳米颗粒.实验过程中,优化了多巴胺聚合温度、时间和金膜生长时间,最佳反应条件为:多巴胺聚合温度10℃,聚合时间15 min,金纳米晶种镀膜时间5 min.最优条件下制备的枝角状金膜光纤LSPR传感器在1.333~1.381的折射率区间,灵敏度高达4091 nm/RIU.进一步考察了传感器的稳定性,发现经过溶剂冲洗、透明胶带撕拉与食人鱼溶液浸泡等处理后,传感器仍能保持光谱信号的稳定.此外,镀膜液采用质量分数为0.01%的氯金酸,仅为传统方法用量的1/10,因此在制备成本方面更具经济性.将人免疫球蛋白G固定在LSPR传感器上,可实现兔抗人免疫球蛋白G在0~75μg/mL浓度区间的定量检测,其灵敏度为0.086(nm/μg)·mL.

Branched gold nanostructures have unique sharp tips and“hot spot”,which can strongly enhance their surrounding electric fields.As a result,branched nanoparticles have strong local surface plasmon resonance(LSPR)signals.Herein,gold nanomaterials with branched nanostructures were in situ synthesized on an optical fiber,and optical fiber LSPR sensors were fabricated and applied for immunoassays.An adhesive layer of polydopamine(PDA)was first prepared on the preprocessed optical fiber and then applied to bind gold seeds.Based on in situ reduction and silver induction,gold nanomaterials with branched nanostructures were fabricated on an optical fiber.The temperatures and time of dopamine polymerization,as well as the gold plating time,were optimized.The optimized values are set as 10℃,15 min,and 5 min.The LSPR sensor fabricated under optimal condition showed a high sensitivity of 4091 nm/RIU with a refractive index ranging from 1.333 to 1.381.Moreover,high stability of the fabricated sensor was demonstrated by comparing the spectrum of the original sensor with the spectra of the sensor after solvent rinsing,scotch tape tearing,and immersion in piranha solution.In addition,0.01%gold chloride was applied as a plating solution,whose concentration was only one-tenth of that of the traditional methods.As a result,the presented method is more economical.Moreover,HIgG was immobilized on the gold film to detect RAHIgG.The fabricated biosensor reached a detection sensitivity of 0.086(nm/μg)·mL during the RAHIgG concentration of 0—75μg/mL.