Alves P, Hugo A A, Szymanowski F, Tymczyszyn E E, Pérez P F, Coelho J F J, Simões P N, Gómez-Zavaglia A
CIEPQPF, Departamento de Engenharia Química, Universidade de Coimbra, Polo II, Pinhal de Marrocos, 3030-790 Coimbra, Portugal.
Centro de Investigación y Desarrollo en Criotecnología de Alimentos (Conicet La Plata, UNLP), RA-1900, Argentina.
Colloids Surf B Biointerfaces. 2014 Nov 1;123:446-51. doi: 10.1016/j.colsurfb.2014.09.043. Epub 2014 Sep 28.
The physicochemical characterization of polymer liposome complexes (PLCs) prepared with lipids of lactic acid bacteria and poly(N,N-dimethylaminoethyl methacrylate) covalently bound to cholesterol (CHO-PDMAEMA) was carried out in an integrated approach, including their stability upon preservation and incorporation into eukaryotic cells. PLCs were prepared with different polymer:lipid molar ratios (0, 0.05 and 0.10). Zeta potential, particle size distribution and polydispersity index were determined. The optimal polymer:lipid ratio and the stability of both bare liposomes and PLCs were evaluated at 37 °C and at different pHs, as well as after storage at 4 °C, -80 °C and freeze-drying in the presence or absence of trehalose 250 mM. Internalization of PLCs by eukaryotic cells was assessed to give a complete picture of the system. Incorporation of CHO-PDMAEMA onto bacterial lipids (ratio 0.05 and 0.10) led to stabilization at 37 °C and pH 7. A slight decrease of pH led to their strong destabilization. Bacteria PLCs showed to be more stable than lecithin (LEC) PLCs (used for comparison) upon preservation at 4 and -80 °C. The harmful nature of the preservation processes led to a strong decrease in the stability of PLCs, bacterial formulations being more stable than LEC PLCs. The addition of trehalose to the suspension of liposomes stabilized LEC PLC and did not have effect on bacterial PLCs. In vitro studies on Raw 264.7 and Caco-2/TC7 cells demonstrated an efficient incorporation of PLCs into the cells. Preparations with higher stability were the ones that showed a better cell-uptake. The nature of the lipid composition is determinant for the stability of PLCs. Lipids from lactic acid bacteria are composed of glycolipids and phospholipids like cardiolipin and phosphatidylglycerol. The presence of negatively charged lipids strongly improves the interaction with the positively charged CHO-PDMAEMA, thus stabilizing liposomes. In addition, glycolipids and phosphatidylglycerol act as intrinsic protectants of PLCs upon preservation. This particular lipid composition of lactic acid bacteria makes them natural formulations potentially useful as drug delivery systems.
采用综合方法对由乳酸菌脂质与共价结合胆固醇的聚（N，N - 二甲基氨基乙基甲基丙烯酸酯）（CHO - PDMAEMA）制备的聚合物脂质体复合物（PLCs）进行了物理化学表征，包括其在保存时以及掺入真核细胞后的稳定性。以不同的聚合物：脂质摩尔比（0、0.05和0.10）制备了PLCs。测定了zeta电位、粒径分布和多分散指数。在37°C和不同pH值下，以及在4°C、-80°C保存和存在或不存在250 mM海藻糖的情况下进行冷冻干燥后，评估了最佳聚合物：脂质比以及裸脂质体和PLCs的稳定性。评估了真核细胞对PLCs的内化情况，以全面了解该系统。将CHO - PDMAEMA掺入细菌脂质中（比例为0.05和0.10）可在37°C和pH 7下实现稳定。pH值略有下降会导致其强烈失稳。在4°C和-80°C保存时，细菌PLCs比用于比较的卵磷脂（LEC）PLCs更稳定。保存过程的有害性质导致PLCs的稳定性大幅下降，细菌制剂比LEC PLCs更稳定。向脂质体悬浮液中添加海藻糖可稳定LEC PLCs，而对细菌PLCs没有影响。对Raw 264.7和Caco - 2/TC7细胞的体外研究表明，PLCs能有效掺入细胞。稳定性较高的制剂表现出更好的细胞摄取。脂质组成的性质决定了PLCs的稳定性。乳酸菌的脂质由糖脂和磷脂如心磷脂和磷脂酰甘油组成。带负电荷的脂质的存在强烈改善了与带正电荷的CHO - PDMAEMA的相互作用，从而稳定了脂质体。此外，糖脂和磷脂酰甘油在保存时作为PLCs的内在保护剂。乳酸菌这种特殊的脂质组成使其成为潜在可用作药物递送系统的天然制剂。
