Study On The Interaction Of Gold Nanoparticles With Biomolecules And Its Application

Gold nanoparticles (GNPs) have received great attention in the development of visual sensing schemes owing to some special physical and chemical properties. Recently, as analytical probes and electrochemical sensors, gold nanoparticles have been extensively employed in biotechnological and chemical systems. The surface of gold nanoparticles has strong affinity with many agents. The interaction of GNPs with drug and trypsin was studied in this work, providing valuable theory basis for electrochemical sensors, biosensors and drug delivery.The GNPs were prepared by sodium citrate reduction method, and its diameter was about13nm. GNPs are seen to readily bind amine functional groups by electrostatic attraction, resulting in the aggregation of GNPs. The well-dispersed gold nanoparticle solution is red, whereas aggregated gold nanoparticle solution appears as a blue (or purple) colour. The major advantage of colorimetric assays is that molecular recognition event can be transformed into colour changes, which can be easily observed by the naked eye, and therefore sophisticated instruments are not required. The interaction between GNPs with Vitamin B1, aminoglycoside antibiotics and tetracycline antibiotics was investigated by UV-vis absorption. It was found that the interaction caused the aggregation of GNPs with a red-to-purple-to-blue color change, and its absorption band of GNPs red shifted and broadened. The experimental parameters were optimized, under optimal experimental conditions, the linear range of the colorimetric sensor was calculated. The interaction between aminoglycoside antibiotics and GNPs was strongest, the reaction was completed at once under normal temperature, the reaction between tetracycline antibiotics and GNPs was almost completed within10min, and the reaction between Vitamin B1and GNPs was almost complete within20min. Without the use of expensive apparatus, low-cost and convenient, the colorimetric assays of GNPs is promising for foods and clinical analysis. The interaction between GNPs and trypsin was studied using optical spectroscopy. UV-vis and fluorescence spectra show that a spontaneous binding process occurred between GNPs and trypsin. Results showed that GNPs had a strong ability to quench the intrinsic fluorescence of trpsin through a static quenching procedure. The binding constants (K) were calculated according to the relevant fluorescence datas. The thermodynamic parameters (ΔH, ΔS and ΔG) showed that electrostatic force played a major role in the binding interaction between GNPs and trypsin. The distance r between GNPs and trypsin was obtained according to Foster’s non-radioactive energy transfer theory. The effect of GNPs on the conformation of trypsin was analyzed using synchronous fluorescence spectra..