Effect of D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) on surfactant monolayers.
Colloids Surf B Biointerfaces 2011;
85:116-24. [PMID:
21398100 DOI:
10.1016/j.colsurfb.2011.01.021]
[Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Revised: 01/12/2011] [Accepted: 01/16/2011] [Indexed: 12/17/2022]
Abstract
In the present study, the effects of an amphiphilic polymer, d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) on model surfactant monolayers dipalmitoylphosphatidylcholine (DPPC), a binary mixture of DPPC with palmitoyloleoyl phosphatidylglycerol (DPPC-POPG) 9:1 (w/w) and binary mixture of DPPC and oleic acid (DPPC-OA) were evaluated. The ability of TPGS to act as an antioxidant adjuvant for pulmonary surfactants was also evaluated. Compression isotherms of surfactant monolayers at 37 °C in a Langmuir-Blodgett trough showed that DPPC and DPPC:TPGS mixed monolayers (1:0.25-1:1, w/w) exhibited low minimum surface tensions (MST) of 1-2 mN/m. Similarly [DPPC:POPG (9:1, w/w)]:TPGS mixed films of 1:0.25-1:1 weight ratios reached 1-2 mN/m MST. DPPC:POPG:TPGS liposomes adsorbed to surface tensions of 29-31 mN/m within 1s. While monolayers of DPPC:OA (1:1, w/w) reached high MST of ∼11 mN/m, DPPC:OA:TPGS (1:1:0.25, w/w) film reached near zero MST suggesting that low concentrations of TPGS reverses the effect of OA on DPPC monolayer. Capillary surfactometer studies showed DPPC:TPGS and [DPPC:POPG (9:1, w/w)]:TPGS liposomes maintained 84-95% airway patency. Fluorescence spectroscopy of Laurdan loaded DPPC:TPGS and DPPC:POPG:TPGS liposomes revealed no segregation of lipid domains in the lipid bilayer. Addition of TPGS to soybean liposome significantly reduced thiobarbituric acid reactive substance (TBARS) by 29-39% confirming its antioxidant nature. The results suggest a potential use of TPGS as an adjuvant to improve the surfactant activity as well as act as an antioxidant by scavenging free radicals.
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