Dendrimer building blocks are a single branched polymer composed of three layers of structure, which are the core, dendrite layer, and outer surface layer. The core layer, dendrite layer, and surface layer can introduce functional elements and functional groups. At present, the application of dendrimers in the fields of chemical sensors, catalysts, electronics, photonics, and photonics has attracted extensive attention.
Dendritic molecules have unmatched advantages over traditional organic polymers: (1) Combining cavities. Dendritic macromolecules have a three-dimensional controllable topological structure, and there are cavity structures of different sizes in the skeleton. The cavity and binding points in the inner layer can be introduced into the catalytic center to improve the catalytic efficiency, and can also be used as a carrier for material transfer to wrap genes, drug molecules, antibodies, and vaccines. (2) Molecular structure. Dendritic molecules are ideal organic macromolecules with a degree of dispersion and a specific skeleton structure, so they are very suitable for the supramolecular assembly design of nanomaterials. In addition, its size is usually distributed at the nanometer level, making it the most ideal molecule for simulating natural proteins. (3) Group distribution. The end groups of dendrimers are all densely distributed on the outer surface of the molecular topology, which can significantly improve the drug loading capacity. Moreover, this symmetrical three-dimensional structure does not cause chain entanglement, so the viscosity is low and the activity is high so that an ultra-thin film with certain characteristics can be formed. These characteristics of dendrimers also make them widely studied in many fields of life sciences.
- Protein simulation: Dendritic macromolecules have a controllable molecular structure and size on the nanometer scale, so the most prominent feature is the simulation of natural protein structures. Some researchers have designed and studied the size distribution, electrophoresis results, and other biological simulation characteristics of PAMAM dendrimers. The results show that PAMAM molecules are very ideal molecules for simulating proteins, which can be called "artificial proteins." In the PAMAM dendrimer family, many molecules perfectly match the size and shape of some major protein structures or biological assemblies (e.g. insulin, cytochrome). Therefore, these molecules can be used to simulate some special functional proteins.
- Guest molecular carrier: Dendritic macromolecules have a clear molecular structure and are divided into a large number of holes, so they are often used to disperse precious metal catalysts, coat anti-cancer drugs, or genetic information, and special organic molecules. Dispersing noble metals with dendrimers can greatly improve their metal catalytic efficiency. In addition, human dendrimers can also be used to load drugs to reduce drug toxicity and improve drug efficacy.
Figure 1. Drawing of a dendrimer carrier encapsulating hydrophobic drug molecules (A) and dendrimer-drug conjugate (B).
- Artificial light capture system: Artificial light capture systems are expected to convert solar energy into chemical energy and store it. When designing the light capture system, a large number of chromophores need to be arranged to form a larger light absorption section, and the chromophore must be organized to promote energy transmission. Dendrimers meet this point, and a large number of chromophores can be labeled at the end or branching point of the dendrimer. At present, a large number of polychromophore dendrimers have been designed to achieve the "antenna effect" of biological systems, and the designability of dendritic macromolecules also provides convenience for regulating the optoelectronic properties of molecules.
Figure 2. Artificial photo capture system of porphyrin dendrimer.
- J. P. Zhang. (2015) “Surface-Engineered Dendrimers in Gene Delivery.” Chem. Rev. 115:5274-5300.
- A. M. Goddard. (1998)”Starburst Dendrimers Molecular Shape Contro.” J. Am. Chem. Soc. 111:2339-2341.