斑龜蛋殼和眼鏡蛇蛋殼都是由成分相似的角質蛋白組成卻擁有截然不同的機械性質：斑龜蛋殼堅韌且強硬，蛇蛋殼卻極具延展性並且有媲美彈性蛋白的變形回復能力。大自然利用複雜、多樣的堆疊方式連結這些相似、簡單的基本組成素材，創造出多元、獨特的生物材料機械特性。此研究從材料科學之觀點出發，探討此兩種爬蟲類革質蛋殼在多尺度下的結構與其機械性能。結合生物組織染色與光學顯微鏡觀測比較蛋白質在蛋殼中的分布情形。利用反射式遠紅外線光譜分析自兩種蛋殼抽取出的角蛋白成分發現其具有相似的角蛋白濃度與二級結構組成，確認兩者蛋白質成分極為相似。由掃描式電子顯微鏡的觀測得知，蛇蛋殼是由三層不同排列方式的角蛋白和一層膠原蛋白薄層組成；而龜蛋殼則是單一夾板狀結構排列。兩類蛋殼礦化程度皆由外向內遞減，呈現漸層式的組成與機械性質。對照拉伸、破斷、循環測試與反射式遠紅外線光譜分析結果發現蛇蛋殼結構能提升其塑性與延展度，而龜蛋殼的結構設計能使其具備高彈性模數、降伏強度、拉伸強度。
蛋殼雖然要足夠強韌以保護幼兒，但同時要能讓幼兒順利破開孵化。龜蛋殼與蛇蛋殼兩者迥異的機械特性，也讓他們的幼兒演化出不同的破蛋策略。透過穿刺測試與對照斑龜尖錐狀卵齒結構，我們成功發現從外部穿刺斑龜蛋殼相對費力，卻有利於斑龜幼兒可以從內省力地破開蛋殼。眼鏡蛇蛋內層大量的刮痕與刀片狀的卵齒，暗示其較有可能利用重複刮磨蛋殼的破蛋機制，來突破此高度變形能力的蛋殼。
透過觀察與比較兩種爬蟲類革質蛋殼的結構與機械特性，學習他們不同的強化機制，將啟發我們設計出新一代輕型、強韌的高分子材料，或是可調式、多功能機械性質的複合材料。並可以進一步運用在軟性基板、封裝工程，與生醫材料等領域。

Turtle eggshells and snake eggshells are both composed of keratin yet exhibit distinctly different mechanical properties. Under deformation, turtle eggshells behave as typical keratin which is stiff and strong while snake eggshells behave as elastin that is extensible and reversible. It is interesting to know how nature uses the same building block but mergers structure in different ways to achieve unique mechanical properties. In this study, the structural and mechanical design of eggshells of cobra snake (Naja atra) and Chinese striped-neck turtle (Ocadia sinensis) are investigated and compared. Hierarchical structure is observed by optical microscopy and FE-SEM. Crystalline minerals are analyzed by X-ray diffraction and compositions are confirmed by tissue staining methods and EDS. Results of tensile test, fracture test, and cyclic test are analyzed in combination with ATR-FTIR examination. Various toughening mechanisms are unveiled: Snake eggshell exhibits structural enhanced plasticity and extensibility while turtle eggshell is plywood structural promoted stiffness and strength.
Dual functions are performed by both reptilian eggshells that protect hatchlings from outer attacks and enable them to break the eggshells easily from inside. However, the structure and mechanical responses of the two eggshells are so different that they evolve unique structures and strategies to break the eggshells. The directionally-dependent penetration resistance of the turtle eggshell and the sharp, cone-liked egg tooth of baby turtle successfully serve as protection from outside but enable effective penetration from inside. Plenty of scratch channels in the inner membrane of snake eggshell and the blade-liked egg tooth imply a repeated slicing strategy adopted by baby snake to break through the ductile eggshell.
Inspirations from the structural and mechanical designs of two reptilian eggshells may lead to the novel synthesis of tough, extensible, lightweight polymer-based composites which can be applied in advanced flexible devices, packaging and bio-medical fields.

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