Hillberg Anna L, Tabrizian Maryam
Department of Biomedical Engineering, and Faculty of Dentistry, Duff Medical Science Building, 3775 University Street, McGill University, Montreal, H3A 2B4, Canada.
Biomacromolecules. 2006 Oct;7(10):2742-50. doi: 10.1021/bm060266j.
Encapsulated cells were formed from the assembly of cationic and anionic alternating layers using a number of polyelectrolyte-based systems. Chitosan, alginate, hyaluronic acid, and oligonucleotides were used as polyelectrolytes to encapsulate individual E. coli cells, which were used as a model. Zeta potential measurements taken for both chitosan/alginate and chitosan/hyaluronic acid systems indicate successful layer-by-layer (LbL) deposition and gave full reversal of the surface change eight times. Layer adsorption was further observed by fluorescence microscopy, and, through a newly developed protocol for sample preparation, transmission electron microscopy micrographs clearly showed the presence of LbL assembly on the outer layer of the cell membrane, in the nanometer range. A second generation of E. coli cells could be grown from encapsulated first generation cells, demonstrating that the cellular activity was not affected by the presence of polyelectrolyte multilayers. Hybridization between attached oligonucleotide sequences and the complementary sequence was demonstrated by both fluorescence spectroscopy and microscopy. Fluorescence energy transfer data recorded after hybrid formation showed that at a molar ratio of 10:20 (donor:acceptor), Q and I were 92.3% and 52.5%, respectively, which suggests that fluorescein fluorescence was quenched by 92.3% and that the fluorescence of rhodamine was enhanced by 52.5%. Oligonucleotide incorporation was stabilized by deposition of four alternating layers, hence offering not only the potential use of the encapsulated cell as a bio-recognition system but also its application in a number of fields such as oligonucleotide delivery, gene therapy, and the use of DNA as an immunocompatible coating.
使用多种基于聚电解质的系统，通过阳离子和阴离子交替层的组装形成了包封细胞。壳聚糖、藻酸盐、透明质酸和寡核苷酸被用作聚电解质来包封单个大肠杆菌细胞，大肠杆菌细胞用作模型。对壳聚糖/藻酸盐和壳聚糖/透明质酸系统进行的zeta电位测量表明成功进行了逐层（LbL）沉积，并且表面电荷完全反转了八次。通过荧光显微镜进一步观察到层吸附，并且通过新开发的样品制备方案，透射电子显微镜照片清楚地显示了在细胞膜外层存在纳米级的LbL组装。第二代大肠杆菌细胞可以从包封的第一代细胞中生长出来，这表明细胞活性不受聚电解质多层膜存在的影响。荧光光谱和显微镜都证明了附着的寡核苷酸序列与互补序列之间的杂交。杂交形成后记录的荧光能量转移数据表明，在摩尔比为10:20（供体：受体）时，Q和I分别为92.3%和52.5%，这表明荧光素荧光被淬灭了92.3%，罗丹明荧光增强了52.5%。通过沉积四个交替层使寡核苷酸掺入得以稳定，因此不仅提供了将包封细胞用作生物识别系统的潜在用途，还提供了其在寡核苷酸递送、基因治疗以及将DNA用作免疫相容性涂层等多个领域的应用。
