Active Drug Targeting by PEGylated Ligands

Active targeting takes advantage of ligand-receptor, antigen–antibody and other forms of molecular recognition to deliver a particle or drug to a specific location. To prolong their circulation time in vivo and promote distribution on different tissues and organs specifically, poly(ethylene glycol) (PEG) is grafted onto the nanocarriers’ surface covalently or non-covalently. CD Bioparticles offers custom design of PEG-ligand modified nanoparticles for drug delivery system.

Introduction to PEGylation in Active Drug Targeting

Advanced drug delivery systems using hydrophilic polymers, most notably polyethylene glycol (PEG), is an important development and a well-established method in the field of targeted drug delivery. PEG labeled nanoparticles increase largely the solubility of poorly soluble drugs due to its hydrophilic nature. The hydrophilic outer layer (corona) formed by PEG ligand can enhance the circulation time by evading plasma protein adsorption among various nanoparticles. This steric hindrance is also advantageous in preventing particle aggregation, and thereby maintaining stability and size of NPs in circulation to enhance their permeability and retention effect and consequential tumor targeting efficiency. This is the reason that PEGylated NPs generally accumulate to a much lesser extent in the liver, while to a greater extent in the tumor compared to uncoated NPs. With all this attributes, PEGylation NPs could extend the half-life of therapeutic agents, improve their pharmacokinetic (PK) profiles, thereby reducing their dosing frequency.

Figure 1. The role of PEGylated ligands.

The process of PEGylation can be extended to liposomes, peptides, carbohydrates, enzymes, antibody fragments, nucleotides, small organic molecules and even to different nanoparticle formulations, with some already approved by FDA. PEGylation conjugation techniques can be classified into two types as follows:

• Random PEGylation. PEG chains and target ligands are simultaneously modified on the particle surface.
• Site-specific PEGylation. A new generation PEGylation processes that resulted in well-defined conjugated products with improved product profiles over those obtained through non-specific random conjugations. For example, PEGylated pro-drugs can be efficiently conjugated to targeting moieties by different conjugation chemistry in order to achieve the goal of active targeting. The targeted delivery of the PEGylated molecules at the desired site causes high bioavailability and low systemic toxicity.

So far, PEG-based nanomaterial is one of the most promising candidates for targeting tumor therapies because of their high anticancer drug payload, prolonged circulation half-life, and flexibility and ease of functionalization with specific ligands.

Figure 1. The advantages of PEGylation in drug delivery system. (Mishra, P., et al. Asian Journal of Pharmaceutical Sciences, 2016, 11(3), 337-348.)

Our PEGylated Ligands Featured Services

Our experienced scientists are proficient in synthesizing or modifying PEGylated nanocarriers with a variety of species on the surface in order to achieve active targeting of cancer. Our expertise covers the various ligands conjugation listed below on PEGylated nanocarriers: i)PEGylated protein as antibodies, antibody fragment, growth factors, transferrin, and lactoferrin; ii) PEGylated peptide as tri-peptide Arg-Gly-Asp (RGD) and Angiopep-2; iii)PEGylated small molecule as folic acid (FA), biotin, curcumin, and selectin.

Quotations and Ordering

References:
1. Chen S, Yang K, Tuguntaev RG, Mozhi A, Zhang J, Wang PC, Liang XJ. Targeting tumor microenvironment with PEG-based amphiphilic nanoparticles to overcome chemoresistance. Nanomedicine: Nanotechnology, Biology and Medicine, 2016, 12(2), 269-86.
2. Steichen SD, Caldorera-Moore M, Peppas NA. A review of current nanoparticle and targeting moieties for the delivery of cancer therapeutics. European Journal of Pharmaceutical Sciences. 2013, 48(3), 416-27.
3. Estelrich J, Busquets MA, del Carmen Moran M. Effect of PEGylation on ligand-targeted magnetoliposomes: a missed goal. ACS Omega., 2017, 2(10), 6544-55.
4. Mozar FS, Chowdhury EH. Impact of PEGylated nanoparticles on tumor targeted drug delivery. Current pharmaceutical design, 2018, 24, 1-4.