Jonasson Simon, Bünder Anne, Berglund Linn, Niittylä Totte, Oksman Kristiina
Division of Materials Science, Luleå University of Technology, 97187 Luleå, Sweden.
Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden.
Nanomaterials (Basel). 2022 Oct 2;12(19):3448. doi: 10.3390/nano12193448.
Cellulose nanofibrils can be derived from the native load-bearing cellulose microfibrils in wood. These microfibrils are synthesized by a cellulose synthase enzyme complex that resides in the plasma membrane of developing wood cells. It was previously shown that transgenic hybrid aspen trees with reduced expression of CSI1 have different wood mechanics and cellulose microfibril properties. We hypothesized that these changes in the native cellulose may affect the quality of the corresponding nanofibrils. To test this hypothesis, wood from wild-type and transgenic trees with reduced expression of CSI1 was subjected to oxidative nanofibril isolation. The transgenic wood-extracted nanofibrils exhibited a significantly lower suspension viscosity and estimated surface area than the wild-type nanofibrils. Furthermore, the nanofibril networks manufactured from the transgenics exhibited high stiffness, as well as reduced water uptake, tensile strength, strain-to-break, and degree of polymerization. Presumably, the difference in wood properties caused by the decreased expression of CSI1 resulted in nanofibrils with distinctive qualities. The observed changes in the physicochemical properties suggest that the differences were caused by changes in the apparent nanofibril aspect ratio and surface accessibility. This study demonstrates the possibility of influencing wood-derived nanofibril quality through the genetic engineering of trees.
纤维素纳米原纤可源自木材中天然的承重纤维素微纤丝。这些微纤丝由存在于正在发育的木材细胞质膜中的纤维素合酶复合体合成。先前的研究表明，CSI1表达降低的转基因杂交杨树具有不同的木材力学性能和纤维素微纤丝特性。我们推测，天然纤维素的这些变化可能会影响相应纳米原纤的质量。为了验证这一假设，对野生型和CSI1表达降低的转基因树木的木材进行了氧化纳米原纤分离。从转基因木材中提取的纳米原纤表现出比野生型纳米原纤显著更低的悬浮粘度和估计表面积。此外，由转基因材料制成的纳米原纤网络表现出高刚度，以及吸水率、拉伸强度、断裂应变和聚合度降低。据推测，CSI1表达降低导致的木材性质差异产生了具有独特品质的纳米原纤。观察到的物理化学性质变化表明，这些差异是由表观纳米原纤长径比和表面可及性的变化引起的。这项研究证明了通过树木基因工程影响木材衍生纳米原纤质量的可能性。
