Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, P. O. Box 16300, FI-00076, Aalto, Espoo, Finland.
Department of Applied Physics, School of Science, Aalto University, P. O. Box 16300, FI-00076, Aalto, Espoo, Finland.
Sci Rep. 2019 Dec 20;9(1):19505. doi: 10.1038/s41598-019-56009-6.
The availability of microbially-safe drinking water is a challenge in many developing regions. Due to the well-known antibacterial effect of silver ions, materials used for their controlled release have been widely studied for point-of-use water disinfection. However, even if it is in principle known that chloride anions can suppress the antibacterial efficiency of silver, the majority of previous studies, surprisingly, have not focused on chloride concentrations relevant for freshwaters and thus for practical applications. Here, we prepared low-cost nanocellulose-aluminium oxyhydroxide nanocomposites functionalized with silver nanoparticles. Field samples obtained from Chennai, India were used as a guideline for choosing relevant chloride concentrations for the antibacterial studies, i.e., 10, 90, and 290 ppm. The antibacterial performance of the material against Escherichia coli and Bacillus subtilis was demonstrated and the influence of chloride concentration on the antibacterial effect was studied with E. coli. A 1 h contact time led to bacterial reductions of 5.6 log, 2.9 log, and 2.2 log, respectively. This indicates that an increase of chloride concentration leads to a substantial reduction of antibacterial efficiency, even within chloride concentrations found in freshwaters. This work enables further insights for designing freshwater purification systems that utilize silver-releasing materials.
在许多发展中地区，获得微生物安全的饮用水是一项挑战。由于银离子具有众所周知的抗菌作用，因此已广泛研究用于控制其释放的材料，以用于即时水消毒。然而，即使原则上已知氯离子可以抑制银的抗菌效率，但令人惊讶的是，大多数先前的研究并未关注对于淡水且对于实际应用至关重要的氯离子浓度。在这里，我们制备了用银纳米颗粒功能化的低成本纳米纤维素-氧化铝水合物纳米复合材料。从印度钦奈获得的现场样本被用作选择抗菌研究相关氯离子浓度的指南，即 10、90 和 290 ppm。该材料对大肠杆菌和枯草芽孢杆菌的抗菌性能进行了证明，并研究了氯离子浓度对大肠杆菌抗菌效果的影响。1 小时的接触时间分别导致细菌减少了 5.6、2.9 和 2.2 个对数。这表明，氯离子浓度的增加会导致抗菌效率的大幅降低，即使在淡水中发现的氯离子浓度范围内也是如此。这项工作为设计利用释放银材料的淡水净化系统提供了进一步的见解。
