Background

Growing microbial resistance towards the existing antimicrobial materials appears as the greatest challenge for the scientific community and development of new antimicrobial materials has become an important research objective.

Results

In this work, antimicrobial activity of silver-coated hollow poly(methylmethacrylate) microspheres (PMB) having a diameter of 20–80 µm was evaluated against two bacterial strains, Gram-positive Bacillus subtilis (MTCC 1305) and Gram-negative Escherichia coli (MTCC 443). The polymeric PMMA microspheres were synthesized by solvent evaporation technique and were further coated with silver (Ag) under microwave irradiation on their outer surface using an electroless plating technique. It was observed that Ag was uniformly coated on the surface of microspheres. Characterization of the coated microspheres was performed using optical microscope (OMS), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), UV–Vis spectroscopy, FTIR spectroscopy and thermogravimetric analysis (TGA) techniques. We have shown that the silver-coated microspheres were potent bactericidal material for water as they are highly active against the tested microorganisms. The results of the antibacterial tests indicated that APMB particles showed enhanced inhibition rate for both Gram-positive and Gram-negative bacteria and also exhibited dose-dependent antibacterial ability. The diameters of zone of inhibition were14.3 ± 0.2 mm against B. subtilis and 15.2 ± 0.9 mm against E. coli at a concentration of 8 mg. At this concentration, total removal of both Bacillus subtilis and Escherichia coli was observed. The results of shake flask technique for a concentration of 8 mg showed no bacterial presence after 24 h in both the cases. In other words, the material acted efficiently in bringing down the bacterial count to zero level for the tested strains. During the experiments, we have also confirmed that use of this material for water disinfection does not cause leaching of silver ion in to the water solution. The material can be successfully regenerated by backwashing with water.

Conclusions

Considering the cost-effective synthesis, ability to regenerate and very low level of leaching of the material, it can be projected as an advanced material for water disinfection and antimicrobial application.

中文翻译：

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涂银空心聚甲基丙烯酸甲酯微球的抗微生物活性

背景

对现有抗菌材料的日益增加的微生物耐药性似乎是科学界面临的最大挑战，开发新型抗菌材料已成为重要的研究目标。

结果

在这项工作中，评估了直径为20-80 µm的涂银空心聚甲基丙烯酸甲酯中空微球（PMB）对两种细菌菌株，即革兰氏阳性枯草芽孢杆菌（MTCC 1305）和革兰氏阴性大肠杆菌的抗菌活性。（MTCC 443）。通过溶剂蒸发技术合成聚合的PMMA微球，并使用化学镀技术在微波辐射下在其外表面上进一步用银（Ag）涂覆。观察到Ag均匀地涂覆在微球的表面上。使用光学显微镜（OMS），扫描电子显微镜（SEM），能量色散X射线光谱仪（EDX），UV-Vis光谱仪，FTIR光谱仪和热重分析（TGA）技术对涂覆的微球进行表征。我们已经证明，涂银的微球是有效的水杀菌材料，因为它们对被测微生物具有很高的活性。抗菌测试结果表明，APMB颗粒对革兰氏阳性菌和革兰氏阴性菌均显示出更高的抑制率，并且还表现出剂量依赖性的抗菌能力。抑制区的直径为14.3±0.2 mm枯草芽孢杆菌和15.2±0.9毫米的大肠杆菌，浓度为8毫克。在该浓度下，观察到枯草芽孢杆菌和大肠杆菌均被完全去除。在两种情况下，浓度为8 mg的摇瓶技术结果均显示24小时后无细菌存在。换句话说，该材料有效地降低了被测菌株的细菌计数至零水平。在实验过程中，我们还证实了使用这种材料进行水消毒不会导致银离子浸入水溶液中。通过用水反冲洗可以成功地再生该材料。

结论

考虑到具有成本效益的合成，再生能力以及极低的材料浸出水平，可以将其预测为用于水消毒和抗菌应用的先进材料。