Piperacillin (Pip) is a broad spectrum β-lactam against most Gram-positive and Gram-negative aerobic and anaerobic bacteria. However, bacterial resistance restricts its benefits for the treatment of infectious diseases. Recently, nanoliposomal systems have been investigated as encouraging strategies to address this issue owing to their immense potential. We aimed to encapsulate Pip in liposomal nanoparticles and study their antibacterial activities in vitro against Pseudomonas aeruginosa (P. aeruginosa). Different liposomes were prepared based on the freeze-drying of a monophase solution method. Then, they were characterized in terms of size, zeta potential, polydispersity-index, and morphology. For further analysis, spectra of ATR-FTIR and XRD were taken for liposomal Pip. Encapsulation efficiency (EE) was determined via agar diffusion assay. Also, minimum inhibitory concentrations (MICs) were investigated by the standard broth macro-dilution method. The liposomes were from 100.9 to 444.13 nm with z-potential of − 30.70 to − 10.57 mV. EE of the selected formulation was 53.1%. TEM results showed that the liposomes were nanosized and almost spherical. ATR-FTIR results confirmed the full encapsulation of Pip in nanoliposomes. The X-ray pattern indicated that the liposomal Pip was amorphous. The MIC (10.6 µg/ml) of the nanoliposomal Pip against P. aeruginosa was one-half of the MIC (21.25 µg/ml) of free Pip for the same organisms. Considering four aspects (nanosized liposomes, no need for sterilization, suitable EE and enhanced antibacterial effects), this preparation method seems promising and may be used to overcome the bacterial resistance relative to Pip.

中文翻译：

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使用改进的单相溶液冷冻干燥法将哌拉西林封装在纳米脂质体中：制备、表征和体外抗菌活性

哌拉西林 (Pip) 是一种广谱 β-内酰胺，可对抗大多数革兰氏阳性和革兰氏阴性需氧和厌氧细菌。然而，细菌耐药性限制了其治疗传染病的益处。最近，纳米脂质体系统因其巨大的潜力而被研究为解决这一问题的令人鼓舞的策略。我们的目的是将 Pip 封装在脂质体纳米颗粒中，并在体外研究它们对铜绿假单胞菌（P. aeruginosa）的抗菌活性。基于单相溶液法的冷冻干燥制备了不同的脂质体。然后，根据大小、zeta 电位、多分散指数和形态对它们进行表征。为了进一步分析，对脂质体 Pip 进行了 ATR-FTIR 和 XRD 的光谱。通过琼脂扩散试验确定包封效率（EE）。此外，通过标准肉汤宏观稀释方法研究了最低抑菌浓度 (MIC)。脂质体为 100.9 至 444.13 nm，z 电位为 - 30.70 至 - 10.57 mV。所选配方的 EE 为 53.1%。TEM 结果表明脂质体是纳米级的，几乎是球形的。ATR-FTIR 结果证实了 Pip 在纳米脂质体中的完全封装。X 射线图表明脂质体 Pip 是无定形的。纳米脂质体 Pip 对铜绿假单胞菌的 MIC (10.6 µg/ml) 是相同生物体游离 Pip MIC (21.25 µg/ml) 的二分之一。考虑到四个方面（纳米脂质体、无需灭菌、合适的EE和增强的抗菌效果），这种制备方法似乎很有前景，可用于克服细菌对Pip的耐药性。通过标准肉汤宏观稀释方法研究最低抑菌浓度 (MIC)。脂质体为 100.9 至 444.13 nm，z 电位为 - 30.70 至 - 10.57 mV。所选配方的 EE 为 53.1%。TEM 结果表明脂质体是纳米级的，几乎是球形的。ATR-FTIR 结果证实了 Pip 在纳米脂质体中的完全封装。X 射线图表明脂质体 Pip 是无定形的。纳米脂质体 Pip 对铜绿假单胞菌的 MIC (10.6 µg/ml) 是相同生物体游离 Pip MIC (21.25 µg/ml) 的二分之一。考虑到四个方面（纳米脂质体、无需灭菌、合适的EE和增强的抗菌效果），这种制备方法似乎很有前景，可用于克服细菌对Pip的耐药性。通过标准肉汤宏观稀释方法研究最低抑菌浓度 (MIC)。脂质体为 100.9 至 444.13 nm，z 电位为 - 30.70 至 - 10.57 mV。所选配方的 EE 为 53.1%。TEM 结果表明脂质体是纳米级的，几乎是球形的。ATR-FTIR 结果证实了 Pip 在纳米脂质体中的完全封装。X 射线图表明脂质体 Pip 是无定形的。纳米脂质体 Pip 对铜绿假单胞菌的 MIC (10.6 µg/ml) 是相同生物体游离 Pip MIC (21.25 µg/ml) 的二分之一。考虑到四个方面（纳米脂质体、无需灭菌、合适的EE和增强的抗菌效果），这种制备方法似乎很有前景，可用于克服细菌对Pip的耐药性。