本研究中，結合氨基與醇基NCA開環聚合的機制，順利合成出3armed、4armed、6armed、8armed之星狀聚賴胺酸，並以百分之二十的接枝比例將不同的疏水性基團修飾於聚賴胺酸的側鏈。本實驗利用核磁共振光譜儀與凝膠滲透層析儀鑑定聚胺基酸的合成，探討不同arms數下的氨基酸聚合度與分子量。接枝共聚胺基酸方面，同樣利用核磁共振光譜儀分析不同疏水基團的接枝比例與接枝效率。接著從上述的合成結果中，選出六種特定聚胺基酸進行一系列的抗菌的研究。抗菌的對象主要為耐藥性菌種，菌種為大腸桿菌(E. coli)、克雷伯氏肺炎桿菌(Klebsiella pneumoniae，以下簡稱K.P.)、出血性大腸桿菌(Enterohaemorrhagic E. coli，以下簡稱EHEC)、金黃色葡萄球菌(Staphylococcus aureus，簡稱S.A.)、綠膿桿菌(Pseudomonas aeruginosa，簡稱P. aeruginosa)、痢疾桿菌(Shigella)、沙門氏桿菌(Salmonella)。研究設計為一小時內的抗菌表現，本研究強調短時間抗菌的重要性。計算抗菌IC50的濃度去探討六種聚氨基酸抗菌能力，亦探討不同構型對於抗菌能力的影響。以往的抗菌實驗強調抗菌高分子的生物相容性，本研究以小鼠纖維母細胞(NIH3T3)進行了細胞毒性實驗以及溶血性的研究。最後綜合以上數據，以選擇度的數值評估抗菌聚胺基酸。

We report the synthesis of star homopolypeptides and copolypeptides and their evaluation as antimicrobial agents. It is known that dendritic or star-shaped structures facilitate antimicrobial polypeptides to efficiently interact with cell membranes and consequently enhance antimicrobial potency. Polypeptides with different arms were synthesized by ring-opening polymerization (ROP) of N-carboxyanhydrides (NCAs) using initiators with corresponded number of functional group. GPC and NMR analyses confirmed the successful synthesis of these star polypeptides. Cationic, star polypeptides comprising poly(L-lysine) (PLL) were designed and synthesized as antimicrobial agents against Escherichia coli ,Klebsiella pneumoniae(KP), Pseudomonas aeruginosa and Enterohemorrhagic Escherichia coli(EHEC), Staphylococcus aureus (S. aureus), Pseudomonas aeruginosa(P. aeruginosa), Shigella, Salmonella which are common pathogens found in nosocomial infection. It was found that the star polypeptides exhibited the enhancement of antimicrobial efficacy as compared to linear counterparts without hemolysis and significant cytotoxicity. Unlike the synthesis of antimicrobial, peptide-based dendrimers requiring complex and tedious reaction steps, the synthesis of these star polypeptides is simple and additional functionality can be incorporated by conjugation. Furthermore, antimicrobial polypeptides can overcome antibiotic resistance owing to their unique antibacterial process. Our present results demonstrated that these star polypeptides are promising antibacterial agents.

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