title: The future perspectives of natural materials for pulmonary drug delivery and lung tissue engineering.
abstract: BACKGROUND
  Search for new, functional biomaterials that can be used to synergistically deliver a drug, enhance its adsorption and stimulate the post-injury recovery of tissue function, is one of the priorities in biomedicine. Currently used materials for drug delivery fail to satisfy one or more of these functionalities, thus they have limited potential and new classes of materials are urgently needed.
  
  
  METHODS
  Natural materials, due to their origin, physical and chemical structure can potentially fulfill these requirements and there is already strong evidence of their usefulness in drug delivery. They are increasingly utilized in various therapeutic applications due to the obvious advantages over synthetic materials. Particularly in pulmonary drug delivery, there have been limitations in the use of synthetic materials such as polymers and lipids, leading to an increase in the use of natural and protein-based materials such as silk, keratin, elastin and collagen. Literature search in each specialized field, namely, silk, keratin and collagen was conducted, and the benefits of each material for future application in pulmonary drug delivery are highlighted.
  
  
  CONCLUSIONS
  The natural materials discussed in this review have been well established in their use for other applications, yet further studies are required in the application of pulmonary drug delivery. The properties exhibited by these natural materials seem positive for their application in lung tissue engineering, which may allow for more extensive testing for validation of pulmonary drug delivery systems.
authors.affiliation: The University of Sydney, Faculty of Pharmacy , Sydney, NSW 2006 , Australia.
authors.forename: Sally Yunsun
authors.initials: SY
authors.lastname: Kim
authors.forename: Alice Hai May
authors.initials: AH
authors.lastname: Wong
authors.forename: Ensanya Ali
authors.initials: EA
authors.lastname: Abou Neel
authors.forename: Wojciech
authors.initials: W
authors.lastname: Chrzanowski
authors.forename: Hak-Kim
authors.initials: HK
authors.lastname: Chan
mesh_terms: D000327:Adsorption; D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D016503:Drug Delivery Systems; D004549:Elastin / Q000737:chemistry; D006801:Humans; D008055:Lipids / Q000737:chemistry; D008168:Lung / Q000378:metabolism; D011108:Polymers / Q000737:chemistry; D023822:Tissue Engineering / Q000379:methods*
chemical_list: D001672:Biocompatible Materials; D008055:Lipids; D011108:Polymers; D004549:Elastin
keywords: collagen; keratin; lung drug delivery; lung tissue regeneration; silk