Chitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesChitosan: an integrative biomaterial for lab-on-a-chip devicesS. T. Koev,†‡aP. H. Dykstra,†aX. Luo,bG. W. Rubloff,cW. E. Bentley,bG. F. Payneband R. Ghodssi*aReceived 24th May 2010, Accepted 17th August 2010DOI: 10.1039/c0lc00047gChitosan is a naturally derived polymer with applications in a variety of industrial and biomedicalfields. Recently, it has emerged as a promising material for biological functionalization ofmicroelectromechanical systems (bioMEMS). Due to its unique chemical properties and film formingability, chitosan serves as a matrix for the assembly of biomolecules, cells, nanoparticles, and othersubstances. The addition of these components to bioMEMS devices enables them to perform functionssuch as specific biorecognition, enzymatic catalysis, and controlled drug release. The chitosan film canbe integrated in the device by several methods compatible with standard microfabrication technology,including solution casting, spin casting, electrodeposition, and nanoimprinting. This article surveys theusage of chitosan in bioMEMS to date. We discuss the common methods for fabrication, modification,and characterization of chitosan films, and we review a number of demonstrated chitosan-basedmicrodevices. We also highlight the advantages of chitosan over some other functionalization materialsfor micro-scale devices.1 IntroductionOne of the main challenges in the development of miniaturizedsensors and systems for life science applications continues to bethe integration of biological components. These types of micro-devices typically need to be functionalized with biomoleculessuch as DNA, enzymes, or antibodies to operate with sufficientspecificity and sensitivity. However, the harsh fabrication tech-niques and materials involved in traditional MEMS fabricationare incompatible with the labile biological components.Specialized materials and processes are needed to allow forseamless integration of biology into microdevices. Severalapproaches toward this goal have been demonstrated based onthe use of self-assembled monolayers or surface-immobilizedpolymers.1,2The polymer chitosan is one of the most promisingcandidates for interfacing biology and microdevices, and it is thesubject of this review paper.Chitosan is a polysaccharide derived from naturally occurringchitin. Its unique properties make it attractive for many indus-trial and biomedical applications. Due to its pH dependentsolubility, it forms stable films on various surfaces under neutraland basic pH conditions. Its amine groups serve for covalentaDepartment of Electrical and Computer Engineering, Institute for SystemsResearch (ISR), University of Maryland, College Park, MD, 20742, USA.E-mail: [email protected] Department of Bioengineering, Center for Biosystems Research,University of Maryland, College Park, MD, 20742, USAcDepartment of Materials Science and Engineering, Institute for SystemsResearch (ISR), University of Maryland, College Park, MD, 20742, USA† These authors contributed equally to this work.‡ Currently address: Center for Nanoscale Science and Technology,NIST, Gaithersburg, MD, 20899, USAS: T: KoevStephan Koev was born in Bul-garia in 1981. He received a BSdegree in Electrical Engineeringfrom the US Naval Academy in2004, and MS and PhD degreesin Electrical Engineering fromthe University of Maryland in2007 and 2009, respectively. Hisdoctoral research was in the areaof MEMS for biomedical appli-cations. His interests includemicro- and nano-fabrication,integrated optics, bio-deviceinterfaces, and MEMSmetrology. Currently, he isa postdoctoral research asso-ciate with the Center for Nanoscale Science and Technology at theNational Institute of Standards and Technology, Gaithersburg,MD, USA.P: H: DykstraPeter Dykstra received his B.S.and M.S. degrees in ElectricalEngineering from BucknellUniversity in 2006 and theUniversity of Maryland in 2008,respectively. He is currentlypursuing his Ph.D. in ElectricalEngineering while working atthe MEMS Sensors and Actua-tors Lab (MSAL) at theUniversity of Maryland. Hismaster’s research involved theuse of the biopolymer chitosan ina microfluidic biosensor whilehis current research focuses onan electrochemical microfluidicDNA array for protein sensing. His research interests includebiological and chemical sensors, micro fabrication, microfluidics,and electrochemistry.3026 | Lab Chip, 2010, 10, 3026–3042 This journal is ª The Royal Society of Chemistry 2010CRITICAL REVIEW www.rsc.org/loc | Lab on a Chipattachment of biomolecules, and it can be co-deposited withother polymers or nanoparticles. Several review papers surveythe diverse applications of chitosan,3–11including controlled drugrelease, wound healing, nutrition supplements, water purifica-tion, removal of toxins, scaffolds for tissue engineering, andsemipermeable membranes.Recent advances in chitosan fabrication