Willems Lione, Roberts Stefan, Weitzhandler Isaac, Chilkoti Ashutosh, Mastrobattista Enrico, van der Oost John, de Vries Renko
Physical Chemistry and Soft Matter and Laboratory of Microbiology, Wageningen University and Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands.
Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, United States.
ACS Omega. 2019 May 31;4(5):9135-9143. doi: 10.1021/acsomega.9b01025. Epub 2019 May 23.
Silk-elastin block copolymers have such physical and biological properties that make them attractive biomaterials for applications ranging from tissue regeneration to drug delivery. Silk-elastin block copolymers that only assemble into fibrils at high concentrations can be used for a template-induced fibril assembly. This can be achieved by additionally including template-binding blocks that promote high local concentrations of polymers on the template, leading to a template-induced fibril assembly. We hypothesize that template-inducible silk-fibril formation, and hence high critical concentrations for fibril formation, requires careful tuning of the block lengths, to be close to a critical set of block lengths that separates fibril forming from nonfibril forming polymer architectures. Therefore, we explore herein the impact of tuning block lengths for silk-elastin diblock polypeptides on fibril formation. For silk-elastin diblocks E -S , in which the elastin pentamer repeat is E = GSGVP and the crystallizable silk octamer repeat is S = GAGAGAGQ, we find that no fibril formation occurs for = 6 but that the = 10 and 14 diblocks do show concentration-dependent fibril formation. For = 14 diblocks, no effect is observed of the length (with = 40, 60, 80) of the amorphous block on the lengths of the fibrils. In contrast, for the = 10 diblocks that are closest to the critical boundary for fibril formation, we find that long amorphous blocks ( = 80) oppose the growth of fibrils at low concentrations, making them suitable for engineering template-inducible fibril formation.
丝素 - 弹性蛋白嵌段共聚物具有这样的物理和生物学特性，使其成为从组织再生到药物递送等广泛应用中具有吸引力的生物材料。仅在高浓度下才组装成原纤维的丝素 - 弹性蛋白嵌段共聚物可用于模板诱导的原纤维组装。这可以通过额外引入促进聚合物在模板上形成高局部浓度的模板结合嵌段来实现，从而导致模板诱导的原纤维组装。我们推测，模板诱导的丝素原纤维形成以及因此形成原纤维所需的高临界浓度，需要仔细调整嵌段长度，使其接近区分形成原纤维和不形成原纤维的聚合物结构的一组临界嵌段长度。因此，我们在此探讨调整丝素 - 弹性蛋白二嵌段多肽的嵌段长度对原纤维形成的影响。对于丝素 - 弹性蛋白二嵌段E - S，其中弹性蛋白五聚体重复序列为E = GSGVP，可结晶的丝素八聚体重复序列为S = GAGAGAGQ，我们发现当n = 6时不发生原纤维形成，但n = 10和14的二嵌段确实显示出浓度依赖性的原纤维形成。对于n = 14的二嵌段，未观察到无定形嵌段的长度m（m = 40、60、80）对原纤维长度有影响。相比之下，对于最接近原纤维形成临界边界的n = 10的二嵌段，我们发现长的无定形嵌段（m = 80）在低浓度下会抑制原纤维的生长，使其适合用于工程化模板诱导的原纤维形成。
