• P5 polypeptide is designed to form peptide-based nanofilaments (PFs) and has been demonstrated to exhibit excellent resistance to non-specific protein adsorption. Through a series of experiments, including turbidity measurement, high-performance liquid chromatography (HPLC), enzyme-linked immunosorbent assay (ELISA), fluorescence resonance energy transfer (FRET), and transmission electron microscopy (TEM), it has been shown that P5Fs (nanofilaments formed by P5) have the lowest adsorption capacity for human serum albumin (HSA) among the studied PFs. This property is crucial for its application as a drug carrier, as it can reduce the formation of a biomolecule corona during circulation in the body, thereby minimizing the risk of being recognized and cleared by the immune system.
• In addition, P5Fs display a favorable biodistribution pattern. In vivo studies in mice have revealed that, compared to other PFs, P5Fs have a relatively lower accumulation in the lungs and a higher retention in the plasma one hour after injection. This distribution characteristic is beneficial for the circulation and penetration of drugs in the body, increasing the likelihood of the drug reaching the target site. Moreover, the docetaxel nanofilaments based on P5Fs (DP5Fs) have exhibited outstanding antitumor activity. In various tumor models, such as human breast cancer MCF - 7 tumors, human lung cancer A549 tumors, human colon cancer HT29 tumors, and human prostate cancer PC3 tumors, DP5Fs have demonstrated higher tumor inhibition rates and better survival benefits for animals than traditional drug formulations. These results suggest that P5 polypeptide holds great promise in the development of novel drug delivery systems and cancer therapies.

• Cai Y, Xu T, Zhu B, Chen J, Jiang L, Shan X, Rong R, Li Y, Yu Y, Gao X, Zhu HH, Zhang L, Zhang P, Li Y. Conformation Influences Biological Fates of Peptide-Based Nanofilaments by Modulating Protein Adsorption and Interfilament Entanglement. Adv Mater. 2024 Nov 28:e2409130. doi: 10.1002/adma.202409130. Epub ahead of print. PMID: 39610201.

三氟乙酸（TFA）是一种强酸，常用于从固相树脂中裂解合成的多肽，也可用于提高多肽纯化步骤中的HPLC性能。默认情况下，定制的多肽是以冻干的TFA盐的形式交付的，其中TFA的含量可能高达10-45%。

定制多肽中的TFA可能会导致后续检测数据出现无法解释的差异。例如，nM浓度的TFA已被证明会干扰细胞实验，在某些情况下会抑制细胞增殖，而在其他情况下会增加细胞活力。

TFA去除服务推荐用于:

• 将用于细胞试验的多肽
• 将被用作原料药或制成品的多肽
• 含有大量碱性残基的亲水多肽

干品多肽的重量中不仅仅包含多肽，还包含有一些非肽的组份，如水、被吸收的溶剂、配位离子和盐等。肽的净含量是指肽在其中的重量百分比，这个百分比的数值范围很大，可能从50%到90%，取决于纯度、序列以及合成和纯化的方法，不要将肽的净含量和肽的纯度混为一谈，他们是两个完全不同的概念。纯度通常是通过HPLC测定的。纯度定义的是多肽样品中含正确序列的组分的百分比，而肽的净含量是指样品中肽类物质相对于总物质所占的百分比，肽的净含量通常是氨基酸组分分析或紫外分光法测定的，这个信息主要是在一些对肽的浓度很敏感的实验中，对计算肽的浓度是很重要的。