Center for Biotechnology and Interdisciplinary Studies, Department of Biological Sciences , Rensselaer Polytechnic Institute , 1623 15th Street , Troy , New York 12180 , United States.
Biomacromolecules. 2020 Feb 10;21(2):508-516. doi: 10.1021/acs.biomac.9b01249. Epub 2019 Dec 6.
This work demonstrates a general strategy for introducing remarkable changes in matrix organization and, consequently, functional properties of bacterial cellulose (BC). BC-producing cells were induced, using a well-defined atomized droplet nutrient delivery (ADND) system, to form pellicles with a regular layered morphology that persists throughout the mat depth. In contrast, the morphology of mats formed by conventional static medium nutrient delivery (SMND) is irregular with no distinguishable pattern. ADND also resulted in larger meso-scale average pore sizes but did not alter the fibril diameter (∼70 nm) and crystallinity index (92-95%). The specific modulus and specific tensile strength of ADND mats are higher than those of SMND mats. This is due to the regularity of dense layers that are present in ADND mats that are able to sustain tensile loads, when applied parallel to these layers. The density of BC films prepared by ADND is 1.63-fold lower than that of the SMND BC film. Consequently, the water contents (g/g) of ADND- and SMND-prepared BC mats are 263 ± 8.85 and 99.6 ± 2.04, respectively. A model that rationalizes differences in mat morphology resulting from these nutrient delivery methods based on nutrient and oxygen concentration gradients is proposed. This work raises questions as to the extent that ADND can be used to fine-tune the matrix morphology and how the resulting lower density mats will alter the diffusion of actives from the films to wound sites and increase the ability of cells to infiltrate the matrix during tissue engineering.
这项工作展示了一种在基质组织中引入显著变化的通用策略，从而改变细菌纤维素 (BC) 的功能特性。使用定义明确的雾化液滴营养输送 (ADND) 系统，诱导产生 BC 的细胞形成具有规则层状形态的膜，这种形态在整个垫料深度中都保持不变。相比之下，通过传统静态介质营养输送 (SMND) 形成的垫料的形态是不规则的，没有可识别的模式。ADND 还导致较大的中尺度平均孔径，但不会改变纤维直径（~70nm）和结晶度指数（92-95%）。ADND 垫料的比模量和比拉伸强度高于 SMND 垫料。这是由于 ADND 垫料中存在的致密层的规则性，这些致密层能够在平行于这些层的方向上承受拉伸载荷。通过 ADND 制备的 BC 膜的密度比 SMND 制备的 BC 膜低 1.63 倍。因此，ADND 和 SMND 制备的 BC 垫料的含水量（g/g）分别为 263±8.85 和 99.6±2.04。提出了一种基于营养物质和氧气浓度梯度来解释这些营养输送方法导致垫料形态差异的模型。这项工作提出了一些问题，即 ADND 可以在多大程度上用于微调基质形态，以及较低密度的垫料将如何改变活性物质从膜扩散到伤口部位，并增加细胞在组织工程中渗透基质的能力。
