Ruenraroengsak Pakatip, Florence Alexander T
Centre for Drug Delivery Research, The School of Pharmacy, University of London, 29-39 Brunswick Square, London WC1N 1 AX, UK.
Int J Pharm. 2005 Jul 25;298(2):361-6. doi: 10.1016/j.ijpharm.2005.01.044.
Dynamic light scattering (DLS) has been used to measure the diffusion coefficients of 108+/-7 (+/-S.D.) and 495+/-23 nm positively charged amino latex nanospheres (ALNs) and negatively charged carboxyl latex nanospheres (CLNs) (48+/-7, 91+/-9.8 and 483+/-10 nm) in three different media, water, glycerol aqueous solutions and hydroxypropyl methylcellulose (HPMC) gels. The translational diffusion coefficients (D) of these latex spheres in water were found to be 13.00 (+/-0.12), 5.11 (+/-0.06), 0.89 (+/-0.01) microm2/s for 48, 91 and 483 nm CLN, and 3.26 (+/-0.01) and 0.88 (+/-0.03) microm2/s for 108 and 495 nm ALN, respectively. In Newtonian glycerol aqueous solutions as anticipated the diffusion could be predicted by the Stokes-Einstein relationship over a range of system viscosities. In HPMC gels the results show the deviation of the diffusion coefficient from the Stokes-Einstein equation when the viscosity of the medium is increased. In addition, there was an increase in the polydispersity index (PI) from 0.217 to 0.928 with 108 nm ALN on increasing HPMC concentrations from 0.2% to 0.8% (w/v), which implied an interaction between the positively charged nanospheres and the gel. From the D values, the "effective" or "microscopic" viscosities of the HPMC medium were calculated, and ranged from 0.899 to 0.925 mPa s.
动态光散射（DLS）已被用于测量带正电的氨基乳胶纳米球（ALNs）（直径为108±7（±标准差）和495±23纳米）以及带负电的羧基乳胶纳米球（CLNs）（直径为48±7、91±9.8和483±10纳米）在三种不同介质中的扩散系数，这三种介质分别是水、甘油水溶液和羟丙基甲基纤维素（HPMC）凝胶。结果发现，这些乳胶球在水中的平动扩散系数（D），对于直径为48、91和483纳米的CLN分别为13.00（±0.12）、5.11（±0.06）、0.89（±0.01）μm²/s，对于直径为108和495纳米的ALN分别为3.26（±0.01）和0.88（±0.03）μm²/s。在牛顿型甘油水溶液中，正如预期的那样，在一定范围的体系粘度下，扩散可以用斯托克斯 - 爱因斯坦关系来预测。在HPMC凝胶中，结果表明当介质粘度增加时，扩散系数偏离了斯托克斯 - 爱因斯坦方程。此外，随着HPMC浓度从0.2%（w/v）增加到0.8%，直径为108纳米的ALN的多分散指数（PI）从0.217增加到0.928，这意味着带正电的纳米球与凝胶之间存在相互作用。根据D值，计算出了HPMC介质的“有效”或“微观”粘度，范围为0.899至0.925毫帕秒。
