Construction Of Sensor System And Study Of Antibacterial Properties Based On Novel Nanomaterials

The rapid development of nanotechnology has aroused great interest in the application of nanomaterials.Among them,metal nanomaterials have made great achievements in the field of analysis detection and antibacterial drug due to their small size,high stability,and good biocompatibility.Gold nanoclusters（Au NCs）and gold nanoparticles（Au NPs）are introduced into the sensing system to significantly improve the sensitivity and selectivity of the sensing system due to their excellent structure and optical properties,.In addition,Au NCs combined with various surface ligands have good biocompatibility,multivalent effect,and easy modification,and are a promising antibacterial drug.Based on the above research background,this paper builds a new sensing system based on Au NCs and Au NPs for detecting glutathione（GSH）and Hg²⁺,and studies the antibacterial properties of methionine-protected Au NCs.Build glutathione detection system based on Au NCs internal filter quenching effect and fluorescence enhancement effect.The addition of GSH significantly enhances the fluorescence intensity of Au NCs-Mn O₂ fluorescent nanoprobe to realize the sensitive detection of GSH.The experimental conditions of the sensor system were optimized.The optimal experimental condition was 167 μM Mn O₂,the reaction p H was 4,and the reaction time was 1 h.Under the optimal experimental conditions,a linear equation is established according to the fluorescence intensity of the sensing system and the concentration of GSH.The detection linear range is 1-300 μM.According to the 3σ / S principle,the minimum detection limit is 0.068 μM and the chisquare value is 0.997.The addition of other amino acids and metal ions to the reaction system has no effect on the fluorescence response of the reaction system,proving that the sensor system has good specificity.We used it to analyze human serum samples with GSH added,and the recovery rates of GSH were 97.9-104.92%,and the results confirmed the accuracy and high precision of the Au NCs-Mn O₂ sensing system in actual samples.The colorimetric sensing system of Hg²⁺ is constructed based on exonuclease assisted amplification technology.According to the specific binding of DNA and Hg²⁺,the DNA forms a mismatched double helix structure,which can be digested and broken down by exonuclease Ⅲ（ExoⅢ）to release Hg²⁺.The released Hg²⁺ continues to combine with ss DNA in the system to form a new mismatched double helix Structure to achieve the purpose of loop amplification detection.A linear equation was established based on the ratio of absorbance A610/A520 and Hg²⁺ concentration.The results showed that the method showed a good linear relationship in the range of 0.005 n M-0.06 n M.According to the 3σ/S principle,the minimum detection limit is 200 f M and the chisquare value is 0.998.The addition of different metal ions to the reaction system found no effect on the absorbance of the reaction system.Prove that this method has good selectivity.In addition,the method was successfully applied to the detection of Hg²⁺ in seawater.Study on the antibacterial properties of Au NCs protected by methionine.We synthesized Au NCs protected by methionine by a one-step hydrothermal reduction method.The agar plate counting method showed that Met-Au NCs were more effective against Gram-positive bacteria（Staphylococcus aureus）and Gram-negative bacteria（E.coli）.Good antibacterial effect,while large-sized Met-Au NPs and other nanomaterials BAS-Au NCs,GSH/Met-Au NCs have no obvious antibacterial effect.The minimum inhibitory concentration（MIC）of Met-Au NCs was 34.6 μM and 69.3 μM,and the minimum bactericidal concentration（MBC）was 43.4 μM and 78.1 μM,respectively.At the same time,this article preliminary discusses the antibacterial mechanism of MetAu NCs.Met-Au NCs can destroy the bacterial cell membrane and lead to the leakage of DNA content.At the same time,Met-Au NCs can also induce the increase of ROS content in bacterial cells,thereby killing bacteria.The results prove that Met-Au NCs can be used as an ideal antibacterial agent.