Want A Quick Understanding for Your Dendrimers?Read This!

What Are Dendrimers?

Dendrimers are nano-sized, radially symmetric molecules with well-defined, homogeneous, and monodisperse structure consisting of tree-like arms or branches. These hyperbranched molecules were first discovered by Fritz Vogtle in 1978, by Donald Tomalia and co-workers in the early 1980s, and at the same time, but independently by George R. Newkome.

A variety of dendrimers exist, and each has biological properties such as polyvalency, self-assembling, electrostatic interactions, chemical stability, low cytotoxicity, and solubility. These varied characteristics make dendrimers a good choice in the medical field, and support their diverse applications, such as drug delivery, gene delivery, magnetic resonance imaging contrast agents, and photodynamic therapy.

Are Dendrimers Polymers?

Dendrimers are synthetic polymeric macromolecules, composed of a group of branched monomers, that are characterized by low polydispersity, good biocompatibility, and multivalent surface. Dendrimers are made from several different polymers depending on the biological application, including polyamidoamines (PAMAMs), polyglycerol sulfate, polyamines, and polyamides; in most cases PAMAM dendrimers are used. The modifiable surface of the dendrimers allow conjugation with different molecules, like targeting ligands or drugs. In addition, self-assembly of hydrophilic group with amphiphilic dendrimers leads to deformation of micelles.

How Do Dendrimers Work?

In the different methods, dendrimer grows outward from a multifunctional core molecule. The core molecule reacts with monomer molecules containing one reactive and two dormant groups, giving the first-generation dendrimer. Then, the new periphery of the molecule is activated for reactions with more monomers.

Dendrimers in Drug Delivery?

Dendrimers have come a long way in the last 25 years since their inception. Originally created as a wonder molecule of chemistry, dendrimer is now in the fourth class of polymers. Dr. Donald Tomalia first published his seminal work on Poly(amidoamine) (PAMAM) dendrimers in 1985. Application of dendrimers as a drug delivery system started in late 1990s.

Figure 1. Dendrimers for drug delivery. (Huang, Da, and Decheng Wu, 2018.)
Dendrimers for drug delivery are employed using two encapsulated approaches: (i) formulation and (ii) nanoconstruct. In the formulation approach, drugs are physically entrapped in a dendrimer using non-covalent interactions, whereas drugs are covalently coupled on dendrimers in the nanoconstruct approach. Researchers have demonstrated the utility of PAMAM dendrimers for enhancing solubility, stability and oral bioavailability of various drugs. Drug entrapment and drug release from dendrimers can be controlled by modifying dendrimer surfaces and generations. PAMAM dendrimers are also shown to increase transdermal permeation and specific drug targeting. Dendrimer platforms can be engineered to attach targeting ligands and imaging molecules to create a nanodevice. Dendrimer nanotechnology, due to its multifunctional ability, has the potential to create next generation nanodevices.