| Mesoporous silica nanoparticles (MSN) have been extensively studied for drug delivery because of their uniform tunable and narrow pore size distribution, high porosity, large surface area, and well-defined surface properties which can be easy selectively functionalized the internal and/or the external surface with desired organic functional groups, along with the high chemical and thermal stability and the morphology to be easy controlled and good biological compatibility This paper studied two novel stimuli responsive, MSN-based controlled release delivery systems, ECL substrate Ru(bpy)32+ as guest was encapsulated inside the mesopores with aptamer as "cap", due to the specific aptamer-protein interactions.The enzyme, thrombin, which was responsive to the aptamer as biomolecular stimuli,was detected by using the controlled-release delivery system. The electrogenerated chemiluminescence properties of indole-3-carboxylic acid was studied for the first time. This paper mainly consists of the following issues:1. Controlled-release delivery system using mesoporous silica nanocontainers capped with aptamer.Mesoporous silica nanoparticles (MSN) material with a large average pore diameter and volumes which was modified with kh560 by post-grafting method was synthesized with mesitylene as expander. Two different short-chain DNAs as linkers were immobilized on the exterior surface of MSNs, the linkers and thrombin DNA aptamer could be fused with the double helix structure to constitute caps which could encapsulate the guest Ru(bpy)32+ inside the mesopores. The controlled-release of the guest from the system was accomplished by the addition of thrombin because of the specific affinity to aptamers. On the basis of the controlled-release delivery system, a new label-free method for the detection of thrombin was established. Thrombin was detected by this method in the linear range of 5.0×10?16 mol/L to 8.0×10?14 mol/L with the detection limit of 4.0×10-16 mol/L. In addition, the method has high sensitivity and good specificity recognition, the detection process independent of the interference of other proteins.2. Controlled-release delivery system using magnetic mesoporous silica nanocontainers capped with aptamer.Magnetic nanoparticles are prepared using a convenient chemical co- precipitation process, and the modified of magnetic nanoparticles was explored. Then size-, the pore size controlled APS-grafted mesoporous silica nanoparticles (NH2-Fe3O4@mSiO2) was synthesized by using sol-gel approach. Due to electrostatic interaction with the amino of NH2-Fe3O4@mSiO2 and phosphate groups of aptamer, the unfolded aptamer was absorbed on mesoporous solid surface resulting in the capping of the pores. The controlled-release of the guest from the system was accomplished by the addition of thrombin because of the specific affinity to aptamers. On the basis of the controlled-release delivery system, a new label-free method for the detection of thrombin was established. Thrombin was detected using this method in the linear range of 6.0×10-13 mol/L to 1.0×10-9 mol/L, The reproducibility of the method was assessed by analyzing samples of 2.0×10-12 mol/L thrombin and the R.S.D. of 7 replicate determination was 4.9%. In addition, the method has high sensitivity and good specificity recognition, the detection process independent of the interference of other proteins.3. The study of electrogenerated chemiluminescence properties of indole-3-carboxylic acid.The electrogenerated chemiluminescence(ECL) properties of indole-3-carboxy -lic acid was studied. The results showed that indole-3-carboxylic acid in 0.5 mol/L Bu4NFP6 acetonitrile solution, the scanning potential -2.0-2.0 V, scan rate 0.2 V/s, has good ECL properties. It also found that indole-3-carboxylic acid shows a relatively strong ECL behavior In acetonitrile:water=4:6 mixed solution, 2.0 mol/L KCl, 0.05 mol/L K2S2O8, and a gold conductive layer was formed on the working electrode surface, which was discontinuous spherical polymers. |
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