PubMed · 7208537
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R Kleinsorgen, P H List. 1981. [Emulsions with lecithin].. https://doi.org/10.1002/pauz.19810100102
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The fundamental principles of flow-through optosensors, together with the most significant procedures and alternatives developed in the applications of flow-through optosensors to pharmaceutical analysis are reviewed. The most frequently used solid sensing zones, flow-through cells, manifolds, regeneration step and types of detection are considered. Single parameter, biparameter, and multiparameter sensors developed are reviewed and their most relevant features presented. Finally, a critical comparison with other analytical methodologies/techniques is performed and the potential of flow-through optosensors in pharmaceutical analysis and their future trends discussed.
In vivo drug release from solid lipid nanoparticles (SLN) takes place by diffusion and degradation of the lipid matrix. SLN with different degree of crystallinity were prepared to study the effect of crystallinity on the degradation velocity. These SLN were produced by using glycerides with different length of fatty acid chains and known differences in crystallisation velocity (Dynasan 114 and 116), and using stabilisers interfering differently with the crystallisation process of the lipid matrix (cholic acid sodium salt (NaCh), Poloxamer 407 (Plx 407)). NaCh disturbs the crystallisation process, Poloxamer shows little interference. The particles were characterised by photon correlation spectroscopy (PCS) and differential scanning calorimetry (DSC), degradation velocity was determined directly after production and during storage up to 4 weeks under different storage conditions using an especially developed assay based on the NEFA Test kit. After production, SLN with a lower crystallinity matrix (Dynasan 114 and 116, NaCh) degraded faster than higher crystalline particles (all SLN with Plx 407), and showed a decrease in degradation velocity with increasing crystallinity during storage. Fast crystallising particles made from Dynasan 116 stabilised with the non-interfering Plx 407 showed no change in the degradation velocity during storage. SLN produced with a higher crystalline lipid in combination with the crystallisation-disturbing NaCh (Dynasan 116, NaCh) required a 'ripening time' to reach sufficient crystallinity.
A copolymer of N-isopropylacrylamide and N-acryloylpyrrolidine, which exhibits a lower critical solution temperature (LCST) at 38 degrees C, having a didodecyl group at the chain terminal was synthesized and calcein-loaded liposomes were prepared from a mixture of dioleoylphosphatidylethanolamine and the copolymer. While the contents release from the copolymer-modified liposomes was strongly accelerated around the LCST of the copolymer, some extent of the release was also observed below the LCST, probably because the partly-dehydrated copolymer chains interacted with the liposome membrane. When poly(ethylene glycol) with the number average molecular weight of 550 having a didodecyl group at the chain end was introduced into the copolymer-modified liposomes, the contents release from the copolymer-modified liposomes was effectively suppressed below the LCST but hardly affected above the LCST. As a result, the liposomes exhibited much sharper enhancement of the contents release in a narrow temperature region. The temperature-sensitive contents release property of the copolymer-modified liposomes became less significant in the presence of serum. However, inclusion of the anchor-bearing poly(ethylene glycol) derivative improved the contents release behavior of the copolymer-modified liposomes in the presence of serum.