S18 surfactant/Cremophor EL

Cremophor EL is a non-ionic surfactant composed of ricinoleate polyoxyethylene ether (PEG-35 castor oil) with high hydrophilicity (HLB 14-16) and strong solubilization ability. Its unique molecular structure (hydrophobic castor oil segment combined with hydrophilic polyoxyethylene segment) gives it excellent emulsification, solubilization and biocompatibility, and is widely used in in vitro diagnostics to stabilize colloidal particles, solubilize hydrophobic targets and optimize whole blood detection performance.

Action mechanism

Efficient solubilization: The hydrophobic core is coated with fat-soluble molecules (such as lipid antigens, fluorescent dyes) to improve their solubility and reaction uniformity in the water phase.

Non-hemolytic: mild action on the red cell membrane, suitable for whole blood direct detection (such as chromatographic strips, microfluidic chips), to avoid hemolysis interference with optical signals.

Stability of colloidal particles: adsorbed to the surface of latex/colloidal gold to form a protective layer to prevent aggregation (e.g. signal stability in immunoturbidimetry).

Wide solvent compatibility: miscible with water, ethanol, glycerin and other solvents, suitable for complex reagent systems (such as marker storage solution containing organic solvents).

Low immunogenicity: High biocompatibility, reduced non-specific adsorption of antibodies, reduced background interference (such as ELISA, chemiluminescence detection).

Application scenario

Fat soluble antigen solubilization: Added to the sample diluent, solubilizing membrane binding antigen (such as lipopolysaccharide, cholesterol ester), improve detection sensitivity.

Latex particle stabilizer: Premix in latex microsphere suspension, enhance particle dispersion, optimize turbidity signal uniformity (such as CRP, PCT detection).

Whole blood direct detection: Add sample treatment solution to inhibit red blood cell aggregation and rupture, and eliminate high HCT sample deviation (such as POCT detection).

Fluorescent/chemiluminescent reagents: solubilizing hydrophobic fluorescent dyes or luminescent substrates to improve labeling efficiency and signal strength.

Freeze-drying protectants: Combined with sugars (such as trehalose) to reduce protein/antibody denaturation during freeze-drying and extend the reagent validity.

General use range: 0.05%-2.0% (gradient test required, low concentration preferred).

Matters needing attention

Concentration control: Excessive use (>1%) may result in partial denaturation of the protein or damage to the membrane structure (e.g. enlarged membrane aperture of cellulose nitrate).

Temperature sensitivity: Low temperature (<15℃) may precipitate turbidity, need to preheat to 25-30 ℃ and vortex mixing before use.

Q&A

Insufficient solubilization effect: Cremophor EL concentration may be too low; It is recommended to increase to 0.5% to 1%, or extend the incubation time.

Agglomeration of latex particles: it may react with cationic components; It is recommended to replace the buffer (e.g., Tris-HCl instead of phosphate).

Elevated detection background: may be insufficiently eluted surfactant residue; It is recommended to increase the number of washing times (such as washing the board 5-6 times in ELISA).

Reagent turbidity or stratification: low temperature storage may lead to precipitation; It is recommended to return to room temperature and swirl well, and filter if necessary.

Cremophor  is a trademark of BASF