利用連苯三酚輔助的磺基甜菜鹼聚合物梯度塗層調控纖維母細胞和成骨細胞之行為

Pyrogallol Assisted Poly-Sulfobetaine Gradient Coating to Modulate the Behavior of Fibroblast and Osteoblast Cells

戴聿彬(Piyush Deval)

指導教授 ： 蔡偉博

國立臺灣大學/工學院/化學工程學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202100667

摘要

近來，由於人口和疾病的增加，生物植入物和組織工程的相關產品需求增加，進而促使有關的醫學產業蓬勃發展。然而，當生醫產品植入人體內後，外來物會引起體內的foreign body interactions而導致發炎反應。當醫療設備與體內微環境接觸時，其表面扮演一個重要的角色。由於醫療器械的特性不同於生物器官和組織，所以它們容易有蛋白質的非特異性吸附，進而導致血栓形成並使器械失效。因此，研究生物細胞在異物環境下的行為變得很重要。
化學梯度塗層的目的是在體外的單一裝置上測試多種微環境條件，並且提供類似體內化學梯度變化的信號。目前已經有許多研究以梯度塗層調節細胞和蛋白質的行為。然而，大部分用於製備化學梯度表面的研究多使用氣相沉積，UV輻射方法，浸塗，電化學沉積等這類會需要花費數個小時的製備方式。因此，在這項研究中我們使用一種基於植物的多酚類物質作為輔助，以加速防污梯度塗層的製備。
源自貽貝和植物的多酚類型塗料在表面改質上可以滿足生物相容性的需求。然而，聚合物溶解度差的問題導致一般論文花費相當長的時間進行表面修飾。因此，我們嘗試使用氧化劑（OAs）達到縮短塗覆時間的效果。在第一部分中，我們分析了不同濃度下的氧化劑（過硫酸銨（APS），過硫酸鈉，碘酸鉀，氯酸鉀，硫酸銅和20％甲醇）在不同pH值的PBS中聚合鄰苯二酚（PG）的效果。我們觀察到氧化劑使用的濃度對PG的氧化聚合有關鍵的作用。通過觀察不同條件下的聚合速率和穩定性，我們選擇了APS作為後續的應用，並以聚磺基甜菜鹼共聚物（pSBAE）控制APS的塗覆效果。與浸塗和電化學沉積相比，我們觀察到透過氧化聚合的PG方式，所需塗覆時間可以分別減少80倍和2倍，並且達到一樣的防污效果。
在第二部分中，我們製備了一種化學梯度表面。我們使用APS氧化聚合的PG固定兩性離子pSBAE於表面上，梯度表面由原始玻璃區域、PG塗覆的區域和PG / pSBAE時間相關性沉積區域組成。經改質後的表面在表面潤濕性上有顯著的變化，水接觸角沿梯度方向減小，在塗覆最長時間的底部區域達到最低的接觸角。XPS的表面元素分析和AFM的表面形貌結果證明了梯度表面的形成。此外，為了印證在生物醫學領域上的應用，我們使用了成纖維細胞（L929）和成骨細胞（MG-63）測試表面的調節行為。在PG / pSBAE塗覆時間最長的區域，兩種細胞系均顯示出顯著的細胞貼附差異。細胞在經pSBAE改質的親水性表面上展現圓形的形態，而在原始玻璃和PG塗覆的表面呈現展開的型態。更進一步，我們使用FITC-BSA檢查非特異性蛋白質的吸附。並發現在梯度的不同的區域，蛋白質的吸附一樣展現顯著變化。
最後，我們研究了表面親水性和細胞貼附、蛋白質吸附之間的關係。我們發現表面的親水程度和細胞貼附程度呈線性關係，而和蛋白質吸附程度則可以用多項式表示，曲線回歸的結果也展現R2> 0.99的近似度。這證明了在另一個特性已知的前提下，這是一種用於確定未知的特性的好方法。因此，在這個研究中，我們可以有效地在短時間內製備梯度表面而不減少其防污的性能。

關鍵字

化學梯度 ； 氧化聚合 ； 鄰苯三酚 ； 磺基甜菜鹼 ； 細胞

並列摘要

Recently, medical industries related to bio-implants and tissue engineering are thriving due to the increase in demands of their product because of increase in population and diseases. However, human body cannot always welcome the foreign body interactions, thus causing the problem of inflammation and degradation when any medical device is implanted. Surface of medical devices plays a vital role as it is the first one to come in contact with microenvironment of human body consisting of physiochemical gradients. Since, medical devices have different properties than biological organs and tissues inside the body, they suffer from non-specific adsorption of proteins leading to thrombosis and finally failure of device. Thus, is becomes important to study how biological cells behave with the foreign environment.
Chemical gradient coatings, serves the purpose of testing multiple conditions on a single substrate along with the microenvironment in in vitro as they serve the signals in the form of chemical cues similar to chemical gradients inside the body. A number of research has been performed in preparing chemical gradient to modulate the behavior of cells and proteins. However, most of the methods employed to prepare chemical gradient surfaces are vapor deposition, UV irradiation method, dip coatings, electrodeposition, etc. which takes time in hours to fabricate a conformal surface. In this research, we developed a faster method of plant based polyphenol assisted antifouling gradient coatings.
Mussel and plant based polyphenol coatings serves the requirement of biocompatible molecules for surface modification. However, the time taken to modify the surface using these molecules is quite long with problem of insoluble polymerized products. Therefore, we tried to shorten the time of coating by using oxidizing agents (OAs). In the first part, oxidizing properties of different OAs namely, ammonium persulfate (APS), sodium persulfate, potassium iodate, potassium chlorate, copper sulfate and 20% methanol to polymerize pyrogallol (PG) was analyzed in PBS at different pH values and different concentration w.r.t. PG. It was observed that concentration of OA plays a crucial role in oxidative polymerization of PG. By observing the polymerization rate and stability in different conditions, APS was finally chosen. Poly sulfobetaine copolymer (pSBAE) was used to determine the coating efficacy of the APS. It was observed that in comparison to conventional dip coating and electrochemical deposition, oxidative polymerization of PG can be an effective method to achieve similar antifouling properties by minimizing the time by 80 folds and 2 folds in comparison to conventional dip coating and electrochemical deposition respectively.
In the second part, we developed a chemical gradient surface using oxidative polymerization of PG using APS as an OA to immobilize zwitterionic pSBAE. The regions consisted of pristine glass, pyrogallol coated region and gradient of PG/pSBAE via anchoring mechanism of poly-PG over the length of the surface. Surface wettability showed a significant change after the surface modification. Water contact angle (WCA) decreased along the length of the gradient formation with lowest WCA achieved at the bottom region which was coated for the longest time. Surface elemental analysis by XPS and surface topography by AFM proved the formation of gradient surface. Further, for the application in biomedical field, behavior of fibroblast (L929) and osteoblast (MG-63) cells was modulated. Both cell lines showed a significant difference in cell attachment with lowest on the region coated for longest time with PG/pSBAE. Cells showed round morphology over the surface modified with hydrophilic pSBAE, whereas wide spreading over pristine glass and pyrogallol coated surface was observed. Next, non-specific protein adsorption was examined by using FITC-BSA. A significant change on protein adsorption as found over the different regions of the gradient.
Finally, surface hydrophilicity was correlated with cell attachment and protein adsorption. The correlation for cell attachment with WCA showed a linear fit whereas the correlation of protein adsorption with WCA showed the polynomial fit with R2 >0.99, showing a good method to determine an unknown property by using the correlation if another one is known. Therefore, the work suggests that, gradient surface can be achieved effectively in short interval of time without compromising anti-fouling properties.

並列關鍵字

Chemical Gradient ； Oxidative Polymerization ； Pyrogallol ； Sulfobetaine ； Cells

參考文獻

[1] J. Fuhrman, The hidden dangers of fast and processed food, American journal of lifestyle medicine 12(5) (2018) 375-381.

[2] K. Wong, A.H. Chan, S. Ngan, The effect of long working hours and overtime on occupational health: a meta-analysis of evidence from 1998 to 2018, International journal of environmental research and public health 16(12) (2019) 2102.

[3] S. Park, H. Kook, H. Seok, J.H. Lee, D. Lim, D.-H. Cho, S.-K. Oh, The negative impact of long working hours on mental health in young Korean workers, PloS one 15(8) (2020) e0236931.

[4] N.C. Delarue, Poor Posture: A Social, Industrial, and Medical Problem:(With a Recitation of the Harmful Sequelæ), Canadian Medical Association Journal 77(3) (1957) 252.

[5] K. Remoundou, P. Koundouri, Environmental effects on public health: An economic perspective, International journal of environmental research and public health 6(8) (2009) 2160-2178.