聚氧化乙烯-氨基酸材料之研發與應用

Synthesis, characterization, and bio-applications of peptide hybrid materials

彭心怡(Peng, Sydney)

指導教授 ： 朱一民

國立清華大學/工學院/化學工程學系/博士(2015年)

https://doi.org/10.6843/NTHU.2015.00064

摘要

此研究中，我們將合成出不同PEO/氨基酸類嵌段共聚物，並探討其微胞以及成膠性質與生物相容性。發現此共聚物在低濃度環境下皆可成膠，而改變其分子量可造成水膠具有不同機械強度與成膠性質。造成水膠不同物理性質之原因，推測為胺基酸鏈段形成之二級結構所致。在體外生物相容性測試方面，將軟骨細胞包埋於水膠內進行培養。由結果中發現軟骨細胞基因表現量增加，細胞明顯增生，並且在培養過程中不會產生局部酸性造成pH值下降，可作為良好之軟骨細胞培養載體。在掃描式電子顯微鏡檢測下，可看出水膠結構型態為膠原纖維狀，並且可看出軟骨細胞分泌細胞外間質附著於纖維之中，顯示水膠材料對於軟骨細胞生物相容性極佳。在glycosaminoglycans細胞染色檢測下，可看出良好軟骨細胞之基因表現。由以上實驗結果可得知，mPEG-alanine水膠在軟骨組織工程有極大應用潛力，未來將朝生物體應用更深入研究探討。

關鍵字

溫感性 ； 組織工程 ； 氨基酸 ； 水膠

並列摘要

In the recent decades, polymer scientists have begun to look into the remarkable achievements of nature to extract particular knowledge for the design of improved biomaterials. This has led to an increase in hybrid polymers that use biological concepts to control the structures and properties of these hybrids. Combining synthetic materials with peptides, the basic building block of the body, into a single macromolecule offers many possibilities previously unachievable with a single material.
Peptides have the tendency to arrange into a variety of secondary structures that may be exploited in copolymer systems for their stabilizing and self-assembling character through hydrogen bonding. This dissertation sets out to study a collection of poly(ethylene oxide)-peptide materials and discusses their synthesis method, chemical and physical characteristics, and potentials as nanoscale carrier and hydrogel for use in drug and cell delivery.
This study uses amine-terminated PEO-based polymers to initiate ring-opening polymerization (ROP) of N-carboxyanhydride (NCA) form of different amino acids to provide peptide hybrid materials. These materials exhibit the propensity for secondary structure formation in both solid and solubilized forms to provide stability and formation of distinct microarchitectures. Two different PEO-based polymers were used, including poly(ethylene oxide) – poly(propylene oxide) – poly(ethylene oxide) (PEO-PPO-PEO, Pluronic®) and methoxy poly(ethylene glycol) (mPEG).
In the first section, amine-terminated Pluronic was used to synthesize a series of Pluronic-oligo(alanine) and Pluronic-oligo(phenylalanine) copolymers. These copolymers were characterized and evaluated for their ability to carry a model hydrophobic drug, curcumin. The encapsulation efficiency of curcumin increased drastically after the addition of peptides. Furthermore, increased cytotoxicity against HeLa cells and cellular uptake were observed with alanine-contianing nanoparticle formulations. These copolymers were also prepared as thermosensitive hydrogels and exhibited decreased gelation concentration, extended in vitro and in vivo residence time, increased cell compatibility, and change in microarchitecture when compared to native Pluronic. Taken together, results suggest that this material may be suitable for various bio-applications
In the second half of the study, amine-terminated mPEG was used to synthesize a series of neutral, positively charged, and negatively charged copolymers using alanine-NCA, lysine-NCA, and aspartic acid-NCA respectively. The microarchitecture of mPEG-poly(alanine) differed significantly from those of other synthetic thermosensitive hydrogels in its strand-like appearance. Chondrocytes cultured within these hydrogels formed homogenous cell clusters with prolonged incubation. Biochemical analysis and real time polymerase chain reaction (real time RT-PCR) were used to evaluate the relationship between hydrogel characteristics and chondrogenic potential of encapsulated chondrocytes. In the final section, oligo(lysine) and oligo(aspartic acid) were added to the peptide end of mPEG-poly(alanine) to increase solubility, helical stability, and confer pH sensitivity.
In summary, these studies demonstrated that peptide hybrid materials are a feasible option for various bio-applications ranging from drug delivery to tissue engineering in both nanoparticle and hydrogel forms. These structures showed excellent stability and potential degradability in vivo as well as biomimetic character. Further in vivo evaluations are underway to examine the ability of hydrogels to support extended drug release and tissue generation. These materials clearly hold promise as an interesting class of biomaterial with a wide range of application.

並列關鍵字

Hydrogel ； Thermosensitive ； Polypeptide ； Tissue Engineering

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