The multidrug resistance (MDR) Escherichia coli having Extended-Spectrum Beta-Lactamase (ESBL) genes and the capacity to create a biofilm acts as a major reduction in the therapeutic effectiveness of antimicrobials. In search of a novel nanocarrier (NC) for targeted delivery of antibiotics, carbon dots (CDs) coated calcium carbonate nanocarriers (CCNC) from organic chicken eggshells conjugated with levofloxacin (Lvx) were synthesized. Our main objectives were to explore the antimicrobial, antibiofilm, and NC potential of CDs coated CaCO₃ Nanocarrier conjugated with levofloxacin (CD-CCNC-Lvx) to combat biofilm-producing MDR ESBL E. coli of urinary tract infection origin. The synthesized NC system was physiochemically characterized, validating the synthesis of CCNC and CD-CCNC-Lvx with a particle size of 56 and 14 nm, respectively. Scanning electron microscopy (SEM) showed rod shape morphology. X-ray diffraction results discovered crystalline and dispersed nanoparticles. In vitro release drug kinetics illustrated sustained release of Lvx. NC system exhibited strong antibacterial and antibiofilm potential against E. coli with a noticeable low minimal inhibitory concentration (MIC). MIC of CCNC was found to be 30 ± 0.1 μg/mL and CD-CCNC-Lvx was 20 ± 0.1 μg/mL for MDR ESBL-producing E. coli. The synergistic effect of NC upon conjugation with Lvx showed incredible activity with 30 mm zone of inhibition and 68% biofilm inhibition. Flow cytometry analysis revealed treated E. coli cells showed 58.69% reduction in cell viability. SEM images of treated bacterial cells showed morphological changes, which were also confirmed by our flow cytometry findings leading to cell membrane damage in E. coli. NC system also downregulated the bla_CTX-M gene in E. coli. The hemolytic analysis proved biocompatibility with human red blood cells (RBCs). It is concluded that CCNC has the potential to be used as NC for target delivery of antibiotics and may combat toxicity of antibiotics as the inhibition of E. coli was noticed at low MIC concentration.

中文翻译：

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左氧氟沙星抗尿路感染来源广谱β-内酰胺酶多药耐药的碳点包覆CaCO3纳米载体的合成与表征

具有超广谱 β-内酰胺酶 (ESBL) 基因的多药耐药 (MDR)大肠杆菌和产生生物膜的能力会大大降低抗菌剂的治疗效果。为了寻找用于靶向递送抗生素的新型纳米载体（NC），合成了与左氧氟沙星（Lvx）缀合的有机鸡蛋壳的碳点（CDs）包覆的碳酸钙纳米载体（CCNC）。我们的主要目标是探索与左氧氟沙星 (CD-CCNC-Lvx) 偶联的 CD 涂层 CaCO _{3纳米载体的抗菌、抗生物膜和 NC 潜力，以对抗产生生物膜的 MDR ESBL}大肠杆菌尿路感染的起源。对合成的 NC 系统进行了物理化学表征，验证了 CCNC 和 CD-CCNC-Lvx 的合成，粒径分别为 56 nm 和 14 nm。扫描电子显微镜 (SEM) 显示棒状形态。X 射线衍射结果发现结晶和分散的纳米颗粒。体外释放药物动力学说明了 Lvx 的持续释放。NC 系统对大肠杆菌表现出很强的抗菌和抗生物膜潜力，具有显着的低最低抑菌浓度 (MIC)。对于产生 MDR ESBL 的大肠杆菌，发现 CCNC 的 MIC 为 30 ± 0.1 μg/mL，CD-CCNC-Lvx 为 20 ± 0.1 μg/mL。NC 与 Lvx 结合后的协同效应显示出令人难以置信的活性，具有 30 mm 的抑制区和 68% 的生物膜抑制。流式细胞术分析显示，处理过的大肠杆菌细胞的细胞活力降低了 58.69%。处理过的细菌细胞的 SEM 图像显示形态变化，我们的流式细胞术发现也证实了这一点，导致大肠杆菌中的细胞膜损伤。NC系统还下调了大肠杆菌中的bla _CTX-M基因。溶血分析证明与人类红细胞 (RBC) 具有生物相容性。得出的结论是，CCNC 有可能被用作 NC 用于抗生素的靶向递送，并且可以对抗抗生素的毒性，如抑制大肠杆菌在低 MIC 浓度下观察到。