m-dPEG®₁₂-amido-dPEG®₂₄-DSPE

Product number 11094, m-dPEG®12-amido-dPEG®24-DSPE, is designed for use in liposomes and micelles. The product contains a lipophilic tail of 1, 2-Distearoyl-sn-glycero-3-phosphoethanolamine (DSPE) and a hydrophilic head consisting of a methoxy-terminated, single molecular weight, discrete polyethylene glycol (dPEG®).

Targeted delivery to cells of payloads such as toxins, peptides, or oligonucleotides is increasingly accomplished using liposomes or micelles. However, without a polyethylene glycol (PEG) coating on the surface, liposomes and micelles clear quickly from the bloodstream via opsonization by the reticuloendothelial system (RES). A sufficiently dense coating of PEG creates a hydrophilic, flexible, steric barrier around the PEGylated liposomes and micelles, thus preventing opsonin proteins from binding to the liposomal or micellar surface. Consequently, liposomes and micelles circulate longer in the bloodstream, which therefore results in lower dosing requirements for the payload.

Phosphatidylethanolamine (PE) conjugated to PEG is frequently used for PEGylated liposomes. DSPE-PEG is the most studied of all PEG-PE conjugates. Several reports show that the optimal PEG molecular weight for a DSPE-PEG conjugate is approximately 2 kilodaltons. This mass of PEG in the conjugate appears to provide the optimum balance between preventing opsonization of the liposome and maintaining effective cellular uptake of PEGylated liposomes. Larger molecular weight PEGs inhibit cellular uptake without providing any additional protection from opsonization.

Unlike traditional, disperse polymer PEGs (Đ > 1), our dPEG® products are designed as single molecular weight products with discrete chain lengths (Đ = 1). This simplifies product analysis because there is no intractable mixture of chain lengths and molecular weights as is the nature of polymeric PEGs. Simplified product analysis saves time and money for cost conscious companies seeking to develop new delivery technologies for diagnostic, therapeutic, or imaging applications.

Product number 11094, m-dPEG®12-amido-dPEG®24-DSPE, is a useful tool for creating, developing, or improving liposomes and micelles. The methoxy terminus of the hydrophilic dPEG® head of PN11094 helps maintain a neutral charge for the molecule while contributing to the surface protection against opsonization of the liposomes or micelles in which it is used. The dPEG® spacer has nearly optimum mass for surface protection, while the lipophilic DSPE tail inserts stably into the lipophilic portion of a liposome or micelle.

Application References:

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