Synthesis Of Electrochemiluminescent Silica Nanomaterials And Its Analytical Application

In this dissertation,we focus on the investigation of novel ECL resonance energy transfer(ECRET)systems utilizing Ru(bpy)₃²⁺-doped silica nanoparticles(RuSiNPs)and luminol-doped silica nanoparticles(luminol-Si NPs)as ECL luminophores.The specific work includes the following three aspects:1.Electrochemiluminescence(ECL)donor of Ru(bpy)₃²⁺-doped silica nanoparticles(RuSiNPs)and acceptor of methylene blue(MB)is developed to achieve electrochemiluminescence resonance energy transfer(ECRET)using the overlap of ECL emission of RuSiNPs with absorption of MB.Owing to ECRET from RuSiNPs to MB,ECL of RuSiNPs is quenched by MB.MB is an oxidation of glucose catalysed by MB only under alkaline condition.MB with blue color is reduced to colourless methylene white by glucose accompanied by the disappearance of the absorbance at650 nm.Accordingly,ECRET is inhibited after the addition of glucose to RuSiNPs and MB mixture.Therefore,ECL“turn-on”detection of glucose is achieved via the proposed ECRET strategy.The proposed ECRET method exhibits high sensitivity for glucose detection with limit of detection(LOD)of 85.4 n M,selectivity towards other metal ions,anions,dopamine or uric acid,and fast response within 5 min.It is also successfully applied in human serum detections and the average recoveries from99.33%to 100.07%are obtained.It widens the application of ECRET in bioanalysis.2.Luminol-doped silica nanopaticles(luminal-Si NPs)are synthesized via water/oil(W/O)microemulsion method in the present work.It is the first time to develop ECRET strategy using luminol-Si NPs for both“turn-off”detection of2,4,6-trinitrophenol(TNP)and“turn-on”detection of anesthetic drug lidocaine hydrochloride(LDC).The spectral overlap of ECL emission of luminol-Si NPs with the absorption of TNP triggers ECRET from luminol-Si NPs to TNP and results in the decreased ECL signals.Besides,the specific interaction between TNP and LDC consumes TNP,accordingly prevents ECRET from luminol-Si NPs to TNP and achieves increasing ECL signals.The proposed ECRET strategy using luminol-Si NPs exhibits fast response(within 10 min),high sensitivity with LOD of 22.4 n M for TNP and 92.5 n M for LDC,respectively.It is also successfully applied in ECRET detection of TNP in lake water,LDC in serum and commercial drug sample detections with satisfactory recoveries.More importantly,ECL of luminol Si NPs is measured via linear sweep voltammetry by electrochemical reduction of dissolved oxygen at negative potential(-1 V)and in no need of adding hydrogen peroxide(H₂O₂).Reactive oxygen species be generated in situ and make luminol-Si NPs system emit ECL,which makes ECL of the whole luminol-Si NPs system more stable than luminol-H₂O₂ system.3.A sensitive electrochemiluminescent immunoassay for alkaline phosphatase(ALP)using p-nitrophenyl phosphate(PNPP)as substrate based on ECRET principle is developed.Luminol-Si NPs are prepared by water/oil(W/O)microemulsion method as mentioned above.PNPP is converted to p-nitrophenol(PNP)in the presence of ALP,which results in the absorption peak shifting from 360 nm to 450 nm.Herein the spectral overlap between absorption spectrum of PNP and electrochemiluminescence(ECL)spectrum of luminol-Si NPs(425 nm)makes energy transfer occur from luminol-Si NPs to PNP.In the optimized conditions,a linear relationship was obtained using this ECRET method at the concentration of ALP from 5 to 50 U/L(r=0.9905)and with the limit of detection(LOD)of 0.8 U/L.This ECRET method exhibits sufficient specificity for ALP over other enzymes such as horseradish peroxidase,trypsin and lysozyme.