page_title: Host–guest chemistry
section_title: Biological application
hierarchical_section_title: Host–guest chemistry / Applications / Biological application
caption_attribution_description: English: Dendrimers
context_page_description: In supramolecular chemistry, host–guest chemistry describes complexes that are composed of two or more molecules or ions that are held together in unique structural relationships by forces other than those of full covalent bonds. Host–guest chemistry encompasses the idea of molecular recognition and interactions through non-covalent bonding. Non-covalent bonding is critical in maintaining the 3D structure of large molecules, such as proteins and is involved in many biological processes in which large molecules bind specifically but transiently to one another.
  Although non-covalent interactions could be roughly divided into those with more electrostatic or dispersive contributions, there are few commonly mentioned types of non-covalent interactions: ionic bonding, hydrogen bonding, van der Waals forces and hydrophobic interactions.
context_section_description: Dendrimers in drug-delivery systems is an example of various host–guest interactions. The interaction between host and guest, the dendrimer and the drug, respectively, can either be hydrophobic or covalent. Hydrophobic interaction between host and guest is considered "encapsulated," while covalent interactions are considered to be conjugated. The use of dendrimers in medicine has shown to improve drug delivery by increasing the solubility and bioavailability of the drug. In conjunction, dendrimers can increase both cellular uptake and targeting ability, and decrease drug resistance.
  The solubility of various NSAIDs increases when it is encapsulated in PAMAM dendrimers. This study shows the enhancement of NSAID solubility is due to the electrostatic interactions between the surface amine groups in PAMAM and the carboxyl groups found in NSAIDs. Contributing to the increase in solubility are the hydrophobic interactions between the aromatic groups in the drugs and the interior cavities of the dendrimer. When a drug is encapsulated within a dendrimer, its physical and physiological properties remains unaltered, including non-specificity and toxicity. However, when the dendrimer and the drug are covalently linked together, it can be used for specific tissue targeting and controlled release rates. Covalent conjugation of multiple drugs on dendrimer surfaces can pose a problem of insolubility.
  This principle is also being studied for cancer treatment application. Several groups have encapsulated anti-cancer medications such as: Camptothecin, Methotrexate, and Doxorubicin. Results from these research has shown that dendrimers have increased aqueous solubility, slowed release rate, and possibly control cytotoxicity of the drugs. Cisplatin has been conjugated to PAMAM dendrimers that resulted in the same pharmacological results as listed above, but the conjugation also helped in accumulating cisplatin in solid tumors in intravenous administration.
caption: Types of Dendrimer. (1.) Encapsulation Interaction (2.) Conjugated Interaction
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