Biotin-dPEG®4-amido-dPEG®24-amido-dPEG®24-DSPE, product number 11386 (PN11386), permits biotin labeling of liposomes and micelles with the lipid 1,2-Distearoyl-SN-glycero-3-phosphoethanolamine (DSPE) modified by conjugation to biotin-labeled single molecular weight, discrete polyethylene glycol (dPEG®) spacer.

Liposomes and Micelles

As nanometer-sized carriers of cytotoxic agents and labels, liposomes and micelles have revolutionized pharmaceutical drug and diagnostic delivery. Liposomes and micelles formed into nanoparticles in the size range of 30 – 200 nm diameter offer reasonably good stability in vitro and in vivo; extended circulation times in the bloodstream; increased accumulation in tumors due to the enhanced permeation and retention (EPR) effect; and reduced systemic toxicity, because cytotoxic agents carried by liposomes and micelles remain inside the carrier until membrane fusion with a cell occurs. Liposomes and micelles can be used passively (without targeting) or actively (with targeting). Several drugs formulated with liposomes or micelles have been approved for clinical use.

In vivo, liposomes and micelles are subject to clearance from the bloodstream by the reticuloendothelial system (RES), also known as the macrophage phagocytic system (MPS). This system works through opsonization. In opsonization, proteins known as opsonins bind to a target molecule to mark the target for destruction. The marked molecule is then engulfed by phagocytes and destroyed. To protect liposomes and micelles from opsonization, various molecules are used to modify the head groups of the lipids from which the liposomes or micelles are composed. Polyethylene glycol (PEG) is the most commonly used surface coating of liposomes and micelles. A sufficiently dense coating of PEG creates a hydrophilic, flexible, steric barrier around the PEGylated liposomes and micelles, thus preventing opsonization and removal by the RES. Consequently, liposomes and micelles circulate longer in the bloodstream, which results in lower dosing requirements.


Biotin, also known as Vitamin B7, is a member of the B vitamin group of vitamins. Biotin forms the strongest known non-covalent bonds with avidin or streptavidin, making it especially useful in a variety of applications. In research and clinical applications, biotin is used in conjunction with avidin or streptavidin in affinity-based assays and drug pre-targeting. Biotin is normally poorly soluble in water, but when combined with amphiphilic polyethylene glycol (PEG), biotin becomes highly water soluble.

PEGylation of Liposomes and Micelles

Traditional PEG is a disperse polymer (Đ > 1). Polymeric PEG consists of a complex mixture of different chain lengths and molecular weights. In contrast, Quanta BioDesign’s dPEG® products are single molecular weight compounds. Each dPEG® product contains a single, discrete PEG chain (Đ = 1). This results in a uniform product that is easier to analyze and use.

Liposomes and micelles are often coated with traditional, polymeric PEG2000 (a polymer PEG having an average molecular weight of 2000 Daltons) at a density of about 5 – 8 mole%. PN11386, biotin-dPEG®4-amido-dPEG®24-amido-dPEG®24-DSPE is equivalent to a comparably functionalized PEG2000. Unlike a traditional PEG2000, however, PN11386 is a single product. That is, the product consists of a single, discrete-length PEG chain conjugated to DSPE, giving a product with a single molecular weight rather than an averaged molecular weight.

PN11386, biotin-dPEG®4-amido-dPEG®24-amido-dPEG®24-DSPE can be used in liposomes and micelles to target liposomes or micelles at avidin- or streptavidin-labeled cells or proteins. In addition, the product can be mixed with other DSPE products from Quanta BioDesign with different reactive, protective, or functional groups. Examples of other functions include methoxy-terminated dPEG® to provide a non-reactive surface coating and active esters (N-hydroxysuccinimidyl ester or tetrafluorophenyl ester) that can be used to add, for example, cytotoxic agents to the liposomal or micellar surface.

The product sizes for PN11386, biotin-dPEG®4-amido-dPEG®24-amido-dPEG®24-DSPE, are 25 mg and 100 mg; however, Quanta BioDesign has the capacity to scale this product to any size you need. If you need large quantities of this product, please contact us for a quote.

Application References:

  1. Kumar, R. Chapter 8 – Lipid-Based Nanoparticles for Drug-Delivery Systems. In Nanocarriers for Drug Delivery; Mohapatra, S. S., Ranjan, S., Dasgupta, N., Mishra, R. K., Thomas, S., Eds.; Micro and Nano Technologies; Elsevier, New York, NY: 2019; pp 249–284. .
  2. Hermanson, G. T. Chapter 18, PEGylation and Synthetic Polymer Modification. Bioconjugate Techniques, 3rd edition. Academic Press: New York, 2013, 787-838.
  3. Hermanson, G. T. Chapter 21, Liposome Conjugates and Derivatives. Bioconjugate Techniques, 3rd edition. Academic Press: New York, 2013, 921-949.
  4. Thau, L.; Mahajan, K. Physiology, Opsonization. In StatPearls; StatPearls Publishing: Treasure Island (FL), 2018.
  5. Stefanick, J. F.; Ashley, J. D.; Kiziltepe, T.; Bilgicer, B. A Systematic Analysis of Peptide Linker Length and Liposomal Polyethylene Glycol Coating on Cellular Uptake of Peptide-Targeted Liposomes. ACS Nano 2013, 7(4), 2935–2947.
  6. Stefanick, J. F.; Ashley, J. D.; Bilgicer, B. Enhanced Cellular Uptake of Peptide-Targeted Nanoparticles through Increased Peptide Hydrophilicity and Optimized Ethylene Glycol Peptide-Linker Length. ACS Nano 2013, 7(9), 8115–8127.
  7. Noble, G. T.; Stefanick, J. F.; Ashley, J. D.; Kiziltepe, T.; Bilgicer, B. Ligand-Targeted Liposome Design: Challenges and Fundamental Considerations. Trends in Biotechnology 2014, 32(1), 32–45.
  8. Saw, P. E.; Park, J.; Lee, E.; Ahn, S.; Lee, J.; Kim, H.; Kim, J.; Choi, M.; Farokhzad, O. C.; Jon, S. Effect of PEG Pairing on the Efficiency of Cancer-Targeting Liposomes. Theranostics 2015, 5(7), 746–754.
  9. Bulbake, U.; Doppalapudi, S.; Kommineni, N.; Khan, W. Liposomal Formulations in Clinical Use: An Updated Review. Pharmaceutics 2017, 9(2), 12.

Additional information

Weight .5 oz
Dimensions .75 × .75 × 2 in