奈米碳點結合多巴胺抑制人類降鈣素纖維之形成

Abstract

生物相容性奈米材料的發展已成為治療和預防人類澱粉樣蛋白疾病的新趨勢。人類降鈣素是由32個胺基酸組成的胜肽，透過甲狀腺周圍的濾泡旁細胞(亦稱C細胞)分泌，在鈣磷代謝中扮演重要的角色。做為胜肽賀爾蒙，它可以用來治療骨質疏鬆症、佩吉特症等骨相關疾病。然而，人類降鈣素於水溶液中傾向形成不可逆的類澱粉蛋白纖維導致該生物利用度以及治療活性降低。鮭魚降鈣素，其有較低的聚集傾向和較高的生物活性，因而常被替代人類降鈣素作為廣泛治療劑。不幸的是，鮭魚降鈣素與人類降鈣素的序列同一性低，導致在臨床治療中會有可能發生嚴重的副作用以及免疫反應之問題。因此，能有效抑制人類降鈣素之聚集並維持其治療活性是非常的重要。水溶性奈米碳點為一小於10 nm微小尺寸的生物友好型奈米材料，其具有低毒性、高生物相容性以及官能多樣化等優點，在生物醫學應用之研究領域上成為新穎的潛力之星。此外，由文獻了解到奈米碳點可以做為抑制劑，來阻止乙型類澱粉蛋白、胰島類澱粉蛋白與胰島素聚集形成類澱粉蛋白纖維。因此，以生物相容性奈米粒子的方法來抑制類澱粉蛋白聚集為一新興的選擇。 本研究中，我們利用由下而上法的方式合成出奈米碳點，並修飾不同的官能基來改變其奈米碳點的表面性質。接著運用硫磺素-T動力學分析和穿透式電子顯微鏡來研究不同官能化的奈米碳點對人類降鈣素聚集之影響並探討這些奈米材料的應用潛力。其中值得注意的是，多巴胺-奈米碳點可以有效阻止人類降鈣素聚集以及降解其類澱粉蛋白纖維。我們推測π-π作用力可能是兩者間的關鍵作用力，不過需進一步的研究來佐證。綜合上述，我們成功地開發一種以典型零維材料的策略來抑制人類降降鈣素之聚集。The development of biocompatible nanomaterials has become a new trend in the treatment and prevention of human amyloid diseases. Human calcitonin (hCT), a peptide consisting of 32 amino acid residues, is secreted by parafollicular cells (also called C cells) and plays a major role in calcium-phosphorus metabolism. As a peptide hormone, it can be used to treat osteoporosis and Paget's disease, but it tends to from amyloid fibrils irreversibly in aqueous solution resulting in reduce of its bioavailability and therapeutic activity. Salmon calcitonin (sCT) is the replacement of hCT as a widely therapeutic agent due to its lower propensity to aggregation and higher bioactivity. Unfortunately, sCT has low sequence identity with hCT leading to severe side effects and immune reactions in clinical therapy. Therefore, it is important to inhibit hCT aggregation and maintain its therapeutic activity. Water-soluble carbon dots (CDs), as a bio-friendly nanomaterial with a tiny size less than 10 nm, have recently been widely studied for potential biomedical applications, due to their low toxicity, high biocompatibility, and many different functionalities. In addition, CDs have been reported to be inhibitors of amyloid formation by β-amyloid (Aβ), Islet amyloid polypeptide (IAPP) and Insulin. Thus, a biocompatible nanoparticle-based approach could present a more promising alternative for inhibition of the amyloid aggregation. In this study, we synthesize CDs through bottom-up method, conjugate different functional groups to change its surface properties and investigate the effects of different functionalized CDs on the aggregation of hCT through Thioflavin-T kinetic assay and transmission electron microscopy (TEM) to explore the potential application of these materials in pharmaceuticals. Among them, it’s worth noting that Dopamine conjugated CDs (DA-CDs) can inhibit hCT aggregation and dissociate preformed hCT amyloids. We speculate that π-π interaction would play a crucial role between hCT and DA-CDs. However, further studies are needed to clarify. In summary, we have successfully developed a typical zero-dimensional material-based strategies to prevent hCT aggregation.