Appearance: White to slightly yellow waxy granules or powderpH (2.5% solution): 6.0–7.5Molecular weight (calculated from hydroxyl value): 7,680–9,510Solubility: Readily soluble in ethanol and water (solution may appear opalescent); insoluble in ether, paraffin oil, and fatty oils.S2 Surfactant, also known as Poloxamer 188, with the trade names Kolliphor P188/Pluronic F-68/Poloxamer 188, is a non-ionic block copolymer surfactant composed of hydrophilic poly(ethylene oxide) (PEO) segments and hydrophobic poly(propylene oxide) (PPO) segments in an alternating structure (PEO-PPO-PEO). Its unique amphiphilicity and biocompatibility make it a versatile excipient in in vitrodiagnostic reagents, widely used for stabilizing biomolecules, improving fluid performance, and optimizing reaction interfaces.
Mechanism of Action
•Biocompatibility: As a pharmaceutical excipient, it is non-toxic and non-immunogenic, allowing direct contact with blood/cells. Suitable for whole blood or live cell detection systems.
•Colloidal Protection and Stabilization: The hydrophobic chains adsorb onto particle surfaces (e.g., colloidal gold, latex microspheres), while the hydrophilic chains form a steric barrier to prevent aggregation and sedimentation.
•Interfacial Activity and Wetting: Reduces liquid-solid interfacial tension, promoting uniform diffusion of samples on test strips or in microfluidic chips and minimizing edge effects.
•Anti-Protein Adsorption: Blocks nonspecific adsorption of proteins/cells onto solid carriers (e.g., nitrocellulose membranes, microplates), reducing background interference.
•Lyoprotection: Maintains the activity of enzymes/antibodies during lyophilization, preventing ice crystal damage (can replace traditional sugar-based protectants).
Application Scenarios
•Colloidal Gold/Latex Reagent Stabilization: Added to marker reconstitution solutions to prevent particle aggregation and enhance colorimetric signal uniformity (e.g., lateral flow test strips).
•Direct Whole Blood Detection: Incorporated into sample diluents to inhibit red blood cell aggregation and improve plasma separation efficiency (e.g., CRP, blood glucose tests).
•Enzyme Reaction System Stabilization: Used as a component in enzyme storage solutions to reduce enzyme inactivation caused by high temperatures or freeze-thaw cycles (e.g., PCR reagents, chemiluminescence systems).
•Microfluidic Chip Wetting Agent: Pre-coated onto hydrophobic channels to optimize the flow performance of blood samples/reagents and prevent bubble retention.
•Lyoprotectant: Combined with sugars (e.g., trehalose) to protect antibody/antigen activity and extend reagent shelf life.
Pluronic F-68 is manufactured by BASF.
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