Direct Force Measurement of Silicone- and Hydrocarbon-Based ABA Triblock Surfactants in Alcoholic Media by Atomic Force Microscopy

Immunoassay Interference by a Commonly Used Blood Collection Tube Additive, the Organosilicone Surfactant Silwet L-720

“…Silwet L-720, the silicone surfactant used by BD for coating the interior of their blood collection tubes (17,20 ), is a member of a family of nonionic silicone surfactants that contain hydrophilic polyoxyalkylene chains. Typically, they exist as homopolymers or copolymers of polyoxyethylene and polyoxypropylene and are attached to a hydrophobic polydimethylsiloxane backbone (1,(21)(22)(23). The molecular structure of Silwet L-720 can be either comb-like, with the polyoxyalkylene chain side-grafted on a polydimethylsiloxane backbone, or linear, arranged with either the AB or ABA type configuration, with A representing a polyoxyalkylene hydrophile and B a polydimethylsiloxane hydrophobe (1,(21)(22)(23).…”

“…Typically, they exist as homopolymers or copolymers of polyoxyethylene and polyoxypropylene and are attached to a hydrophobic polydimethylsiloxane backbone (1,(21)(22)(23). The molecular structure of Silwet L-720 can be either comb-like, with the polyoxyalkylene chain side-grafted on a polydimethylsiloxane backbone, or linear, arranged with either the AB or ABA type configuration, with A representing a polyoxyalkylene hydrophile and B a polydimethylsiloxane hydrophobe (1,(21)(22)(23). The polydimethylsiloxane moiety of Silwet L-720 adsorbs to hydrophobic surfaces such as the plastic (i.e., polyethylene terephthalate) in blood collection tube walls, whereas the hydrophilic, polyalkylene oxide moiety faces outward toward the specimen and prevents erythrocyte adherence (1,3,(21)(22)(23).…”

“…The molecular structure of Silwet L-720 can be either comb-like, with the polyoxyalkylene chain side-grafted on a polydimethylsiloxane backbone, or linear, arranged with either the AB or ABA type configuration, with A representing a polyoxyalkylene hydrophile and B a polydimethylsiloxane hydrophobe (1,(21)(22)(23). The polydimethylsiloxane moiety of Silwet L-720 adsorbs to hydrophobic surfaces such as the plastic (i.e., polyethylene terephthalate) in blood collection tube walls, whereas the hydrophilic, polyalkylene oxide moiety faces outward toward the specimen and prevents erythrocyte adherence (1,3,(21)(22)(23). The findings from this study demonstrate that the addition of increasing concentrations of Silwet L-720 (0 to 400 mg/L) to a serum pool from glass tubes significantly increased the apparent TT 3 concentration when measured on the IMMULITE 2500 analyzer (Fig.…”

Effect of chain lengths of PEO–PPO–PEO on small unilamellar liposome morphology and stability: an AFM investigation

“…Thus, bilayers were found for those systems upon adsorption on mica. On the other hand, with longer PEO chain length (>19 units), a steric barrier can be formed steadily [31]. For EggPC/P85 and EggPC/F87 (Figure 1c and 1d), both bilayer and vesicles coexist.…”

“…It has been suggested that the configuration follows the adsorption model (Model B) when the addition method was used to prepare copolymer-modified liposome [10]. Using NMR, the broadening effect of the 31 P signals (phospatidylcholine) and the 13 C NMR signals of the methyl groups (PPO) indicated molecular mobility was restricted due to copolymer incorporation inside the bilayer [8,9]. Moreover, an increase in hydrodynamic radius and a reduction in the ζ potential were observed suggesting incorporation of the PPO chain into the bilayer [10].…”