Department of Mining-Metallurgy Engineering and Materials Science and BERC POLYMAT, School of Engineering, University of the Basque Country (EHU-UPV), Alameda de Urquijo s/n, 48013 Bilbao, Spain.
J Chem Phys. 2013 Sep 28;139(12):121903. doi: 10.1063/1.4811778.
Fabrication of novel bio-supramolecular structures was achieved by recrystallizing the bacterial surface protein SbpA on amorphous and semicrystalline polylactide derivatives. Differential scanning calorimetry showed that the glass transition temperature (T(g)) for (poly-L-lactide)-PLLA, poly(L,D-lactide)-PDLLA, poly(lactide-co-glycolide)-PLGA and poly(lactide-co-caprolactone)-PLCL was 63 °C, 53 °C, 49 °C and 15 °C, respectively. Tensile stress-strain tests indicated that PLLA, PLGA, and PDLLA had a glassy behaviour when tested below T(g). The obtained Young modulus were 1477 MPa, 1330 MPa, 1306 MPa, and 9.55 MPa for PLLA, PLGA, PDLLA, and PLCL, respectively. Atomic force microscopy results confirmed that SbpA recrystallized on every polymer substrate exhibiting the native S-layer P4 lattice (a = b = 13 nm, γ = 90°). However, the polymer substrate influenced the domain size of the S-protein crystal, with the smallest size for PLLA (0.011 μm(2)), followed by PDLLA (0.034 μm(2)), and PLGA (0.039 μm(2)), and the largest size for PLCL (0.09 μm(2)). quartz crystal microbalance with dissipation monitoring (QCM-D) measurements indicated that the adsorbed protein mass per unit area (~1800 ng cm(-2)) was independent of the mechanical, thermal, and crystalline properties of the polymer support. The slowest protein adsorption rate was observed for amorphous PLCL (the polymer with the weakest mechanical properties and lowest T(g)). QCM-D also monitored protein self-assembly in solution and confirmed that S-layer formation takes place in three main steps: adsorption, self-assembly, and crystal reorganization. Finally, this work shows that biodegradable polylactide derivatives films are a suitable support to form robust biomimetic S-protein layers.
通过在无定形和半结晶聚乳酸衍生物上重结晶细菌表面蛋白 SbpA，制备了新型生物超分子结构。差示扫描量热法显示，（聚 L-丙交酯）-PLLA、聚（L，D-丙交酯）-PDLLA、聚（丙交酯-乙交酯）-PLGA 和聚（丙交酯-己内酯）-PLCL 的玻璃化转变温度（Tg）分别为 63°C、53°C、49°C 和 15°C。拉伸应力-应变测试表明，当在 Tg 以下测试时，PLLA、PLGA 和 PDLLA 表现出玻璃态行为。获得的 PLLA、PLGA、PDLLA 和 PLCL 的杨氏模量分别为 1477 MPa、1330 MPa、1306 MPa 和 9.55 MPa。原子力显微镜结果证实，SbpA 在每个聚合物基底上重结晶，呈现出天然 S 层 P4 晶格（a = b = 13nm，γ = 90°）。然而，聚合物基底影响 S-蛋白晶体的畴尺寸，PLLA 的最小尺寸为 0.011μm²，PDLLA 为 0.034μm²，PLGA 为 0.039μm²，PLCL 的最大尺寸为 0.09μm²。石英晶体微天平耗散监测（QCM-D）测量表明，单位面积吸附的蛋白质质量（~1800ngcm⁻²）与聚合物支撑的力学、热学和结晶性能无关。无定形 PLCL 的蛋白质吸附速率最慢（聚合物的力学性能最弱，Tg 最低）。QCM-D 还监测了溶液中的蛋白质自组装，并证实 S-层的形成分三个主要步骤进行：吸附、自组装和晶体重组。最后，这项工作表明可生物降解的聚乳酸衍生物薄膜是形成坚固仿生 S-蛋白层的合适支撑。
