Drug Radiation Research Department, National Center for Radiation Research and Technology (NCRRT), Egyptian Atomic Energy Authority (EAEA), Cairo, Egypt.
Plant Research Department, Nuclear Research Center, Egyptian Atomic Energy Authority (EAEA), Cairo, Egypt.
BMC Microbiol. 2023 Aug 16;23(1):224. doi: 10.1186/s12866-023-02971-1.
Bimetallic nanoparticles (BNPs) has drawn a lot of attention especially during the last couple of decades. A bimetallic nanoparticle stands for a combination of two different metals that exhibit several new and improved physicochemical properties. Therefore, the green synthesis and design of bimetallic nanoparticles is a field worth exploring.
In this study, we present a green synthesis of silver nanoparticles (Ag NPs), selenium (Se) NPs, and bimetallic Ag-Se NPs using Gamma irradiation and utilizing a bacterial filtrate of Bacillus paramycoides. Different Techniques such as UV-Vis., XRD, DLS, SEM, EDX, and HR-TEM, were employed for identifying the synthesized NPs. The antimicrobial and antibiofilm activities of both the Ag/Se monometallic and bimetallic Ag-Se NPs were evaluated against some standard microbial strains including, Aspergillus brasiliensis ATCC16404, Candida albicans ATCC10231, Alternaria alternate EUM108, Fusarium oxysporum EUM37, Escherichia coli ATCC11229, Bacillus cereus ATCC15442, Klebsiella pneumoniae ATCC13883, Bacillus subtilis ATCC15442, and Pseudomonas aeruginosa ATCC6538 as a model tested pathogenic microbes. The individual free radical scavenging potentials of the synthesized Ag NPs, Se NPs, and bimetallic Ag-Se NPs were determined using the DPPH radical scavenging assay. The degradation of methylene blue (MB) dye in the presence of the synthesized Ag NPs, Se NPs, and bimetallic Ag-Se NPs was used to assess their photocatalytic behavior.
According to the UV-Vis. spectrophotometer, the dose of 20.0 kGy that results in Ag NPs with the highest O.D. = 3.19 at 390 nm is the most effective dose. In a similar vein, the optimal dose for the synthesis of Se NPs was 15.0 kGy dose with O.D. = 1.74 at 460 nm. With a high O.D. of 2.79 at 395 nm, the most potent dose for the formation of bimetallic Ag-Se NPs is 15.0 kGy. The recorded MIC-values for Ag-Se NPs were 62.5 µg mL, and the data clearly demonstrated that C. albicans was the organism that was most susceptible to the three types of NPs. The MIC value was 125 µg mL for both Ag NPs and Se NPs. In antibiofilm assay, 5 µg mL Ag-Se NPs inhibited C. albicans with a percentage of 90.88%, E. coli with a percentage of 90.70%, and S. aureus with a percentage of 90.62%. The synthesized NPs can be arranged as follows in decreasing order of antioxidant capacity as an antioxidant result: Ag-Se NPs > Se NPs > Ag NPs. The MB dye degradation in the presence of the synthesized Ag NPs, Se NPs, and bimetallic Ag-Se NPs was confirmed by the decrease in the measured absorbance (at 664 nm) after 20 min of exposure to sunlight.
Our study provides insight towards the synthesis of bimetallic NPs through green methodologies, to develop synergistic combinatorial antimicrobials with possible applications in the treatment of infectious diseases caused by clinically and industrial relevant drug-resistant strains.
双金属纳米粒子（BNPs）在过去几十年中引起了广泛关注。双金属纳米粒子是由两种不同金属组合而成的，具有多种新的和改进的物理化学性质。因此，双金属纳米粒子的绿色合成和设计是一个值得探索的领域。
在这项研究中，我们使用伽马射线照射和利用芽孢杆菌的细菌滤液，展示了银纳米粒子（Ag NPs）、硒（Se） NPs 和双金属 Ag-Se NPs 的绿色合成。使用 UV-Vis.、XRD、DLS、SEM、EDX 和 HR-TEM 等不同技术来鉴定合成的 NPs。评估了 Ag/Se 单金属和双金属 Ag-Se NPs 的抗菌和抗生物膜活性，针对一些标准微生物菌株，包括巴西曲霉 ATCC16404、白色念珠菌 ATCC10231、交替单胞菌 EUM108、尖孢镰刀菌 EUM37、大肠杆菌 ATCC11229、蜡状芽孢杆菌 ATCC15442、肺炎克雷伯菌 ATCC13883、枯草芽孢杆菌 ATCC15442 和铜绿假单胞菌 ATCC6538，作为模型测试的致病性微生物。使用 DPPH 自由基清除测定法测定了合成的 Ag NPs、Se NPs 和双金属 Ag-Se NPs 的个体自由基清除潜力。通过在合成的 Ag NPs、Se NPs 和双金属 Ag-Se NPs 的存在下降解亚甲基蓝（MB）染料，评估了它们的光催化行为。
根据紫外可见分光光度计，产生最高 O.D. 的 20.0 kGy 剂量= 3.19 在 390nm 处是最有效的剂量。同样，合成 Se NPs 的最佳剂量为 15.0 kGy 剂量，O.D. = 1.74 在 460nm 处。形成双金属 Ag-Se NPs 的最有效剂量是 O.D. = 2.79 在 395nm 处。Ag-Se NPs 的记录 MIC 值为 62.5 µg mL，数据清楚地表明白色念珠菌是最容易受到三种类型 NPs 影响的生物体。Ag NPs 和 Se NPs 的 MIC 值均为 125 µg mL。在抗生物膜试验中，5 µg mL 的 Ag-Se NPs 抑制白色念珠菌的百分比为 90.88%，大肠杆菌的百分比为 90.70%，金黄色葡萄球菌的百分比为 90.62%。合成的 NPs 可以按照抗氧化能力的顺序排列如下：Ag-Se NPs > Se NPs > Ag NPs。在暴露于阳光 20 分钟后，通过测量吸光度（在 664nm 处）的降低，证实了在合成的 Ag NPs、Se NPs 和双金属 Ag-Se NPs 存在下 MB 染料的降解。
我们的研究提供了通过绿色方法合成双金属 NPs 的见解，以开发具有协同组合抗菌作用的组合抗菌剂，可能应用于治疗由临床和工业相关耐药菌株引起的传染病。
