黑曲霉负载银纳米颗粒的制备及其抗菌性能

采用非酶还原法，以黑曲霉菌原位还原银氨离子制备一种新型银纳米颗粒（AgNPs）/菌体复合抗菌材料，着重考察了反应温度与pH值对还原过程和所得复合材料的抗菌性能及稳定性的影响。结果表明，在温度为30℃、60℃和pH 9.5、11.5条件下，能够合成出粒径为6.9～8.2 nm的近球形AgNPs。该AgNPs均匀地分布在菌体表面上，对E.coli显示出高的抗菌性能：最小抑菌浓度(MIC)为217～434 mg·L^-1（以菌粉总质量表示）或8～20 mg Ag·L^-1（以银含量表示）。提高反应温度有利于提高菌体银负载量，但AgNPs粒径增大，抗菌性能有所下降；提高反应pH值有利于提高还原速率，而对抗菌性能影响不显著。复合材料中AgNPs与菌体结合牢固，单位质量复合材料释出的Ag⁺含量为1.7～6.8 mg·g^-1，提高反应温度和pH值后Ag⁺的释出均减少。

In-situ synthesis and antibacterial performance of silver nanoparticle immobilized on Aspergillus niger

A facile and eco-friendly route was presented to in-situ synthesize and immobilize silver nanoparticles (AgNPs, 6.9—8.2 nm)using Aspergillus nigeras both reducing agent and support through the non-enzymatic reduction mechanism.The well-dispersed AgNPs/mycelium composite exhibited excellent antimicrobial activity against E.coli, and the minimal inhibitory concentration (MIC)was 217—434 mg·L^-1(based on the mass of AgNPs/mycelium)or 8—20 mg·L^-1(based on the mass of AgNPs).Although increasing reaction temperature from 30℃ to 60℃ resulted in increase of silver loading, the mean size of the AgNPs became larger at the same time, leading to the decrease of antimicrobial activity.The change of pH value from 9.5 to 11.5 promoted the reaction rate and shortened the reaction time (from 144 h to 24 h), whereas no significant effect was observed on the antimicrobial activity. Finally,the release of AgNPs and Ag⁺ from the AgNPs/mycelium composite was investigated. The results suggested that the prepared AgNPs were supported firmly on Aspergillus niger and the release of Ag⁺ was 1.7—6.8 mg per gram of AgNPs/mycelium.Furthermore, increasing reaction temperature or pH value led to the decrease of Ag⁺ release.