The Study On Interaction Between Inorganic Nanoparticles And Organic Molecule And Its Application In Biochemistry Analysis

Due to the unique physical and chemical properties, inorganic nanoparticles are widely used in all walks of life. Researching the interaction between inorganic nanoparticles and organic molecules is the basis of that the inorganic nanoparticles are used as effective reagents in the biochemical analysis. In this thesis, we investigated the interaction between inorganic nanoparticles and organic molecules, and further explored its application in the fields of biochemical analysis. Specific contents are as follows:(1) The interaction between platinum nanoparticles (Pt NPs) and negative-charged organic molecules has been investigated. It was found that Pt NPs prepared by the citrate reduction of H2PtCl6 could induce a,(3,y,8-4(N-methyl-3-pyridyl)porphine (TMPyP-3) to form J-aggregates through electrostatic interaction. With addition of Pt NPs, the Soret band of porphine showed a distinct redshift. Along with the decrease of the absorbance of TMPyP-3, the resonance light scattering enhanced and the fluorescence intensity weakened. Further investigations demonstrated that the optical signals linearly changed with Pt NP concentration. By investigating the interaction between TMPyP-3 and Pt NPs, we could speculate the aggregating process of porphine analogs, and further explore the morphology evolution.(2) Au nanoparticles as plasmon probes have been used for H2O2 detection. The citrate coated Au nanoparticles are easily gathered in the salt conditions, and the single-stranded DNA (ssDNA) can protect the Au colloids against aggregation through the electrostatic repulsion. Generally speaking, the addition of metal ions will increase the salt effect and weaken of the protective effect of ssDNA. Interestingly, it was found that a small quantity of Fe2+ or Cu2+ ions was able to promote the protective effect of ssDNA on the Au nanoparticles, and further characterizations have been employed to investigate the interaction mechanism among metal ions, ssDNA and Au nanoparticles. The results may promote the possibility of the Au nanoparticle-ssDNA system in a wider field of biological analysis. Based on the fact that ssDNA combining with Fe2+ ions could stabilize Au nanoparticles and protect them against salt-induced aggregation, while hydroxyl radical generated from Fenton reagent (H2O2 and Fe2+ ions) could cleave ssDNA, a novel method for H2O2 detection has been proposed. In this system, the Au nanoparticles were employed as plasmon probes, utilizing the different protective ability of ssDNA after reacting with different concentration of Fenton reagents, H2O2 in the range of 0.2-8.0μmol L-1 could be detected with the limit of determination (LOD) being 40 nmol L-1 (S/N=3), and thus the content of H2O2 in rat encephalon extraction could be successfully detected with the recovery in the range of 98%-103%.(3) Quantum dots (QDs)/polyelectrolyte complex has been fabricated and applied as pH sensor. Firstly, polyacrylic acid (PAA) was mixed with CdTe QDs, and then polyvinyl alcohol (PVA) was added as the matrix elements to generate CdTe/PAA/PVA nanocomposite gels. PAA is a smart pH-sensitive material, which collapses when pH＜4 and stretches while pH＞7. Along with the pH change, the protonation extent as well as the stretching degree of PAA molecules varies, resulting in the movement of the relative spatial location of QDs in the framework of hydrogels. In another word, the concentration of QDs changes in a certain space, which would induce the change of fluorescence intensity. Thereby we established a new type of nanodevice for pH sensing.