Laboratory Methods in Microfluidics PDF
Preview Laboratory Methods in Microfluidics
Laboratory Methods in Microfluidics Laboratory Methods in Microfluidics Basant Giri Center for Analytical Sciences, Kathmandu Institute of Applied Sciences, Kathmandu, Nepal Elsevier Radarweg29,POBox211,1000AEAmsterdam,Netherlands TheBoulevard,LangfordLane,Kidlington,OxfordOX51GB,UnitedKingdom 50HampshireStreet,5thFloor,Cambridge,MA02139,UnitedStates Copyright©2017ElsevierInc.Allrightsreserved. Nopartofthispublicationmaybereproducedortransmittedinanyformorbyanymeans,electronicor mechanical,includingphotocopying,recording,oranyinformationstorageandretrievalsystem,withoutpermission inwritingfromthepublisher.Detailsonhowtoseekpermission,furtherinformationaboutthePublisher’s permissionspoliciesandourarrangementswithorganizationssuchastheCopyrightClearanceCenterandthe CopyrightLicensingAgency,canbefoundatourwebsite:www.elsevier.com/permissions. ThisbookandtheindividualcontributionscontainedinitareprotectedundercopyrightbythePublisher (otherthanasmaybenotedherein). Notices Knowledgeandbestpracticeinthisfieldareconstantlychanging.Asnewresearchandexperiencebroadenour understanding,changesinresearchmethods,professionalpractices,ormedicaltreatmentmaybecomenecessary. Practitionersandresearchersmustalwaysrelyontheirownexperienceandknowledgeinevaluatingandusingany information,methods,compounds,orexperimentsdescribedherein.Inusingsuchinformationormethodsthey shouldbemindfuloftheirownsafetyandthesafetyofothers,includingpartiesforwhomtheyhaveaprofessional responsibility. Tothefullestextentofthelaw,neitherthePublishernortheauthors,contributors,oreditors,assumeanyliability foranyinjuryand/ordamagetopersonsorpropertyasamatterofproductsliability,negligenceorotherwise,or fromanyuseoroperationofanymethods,products,instructions,orideascontainedinthematerialherein. BritishLibraryCataloguing-in-PublicationData AcataloguerecordforthisbookisavailablefromtheBritishLibrary LibraryofCongressCataloging-in-PublicationData AcatalogrecordforthisbookisavailablefromtheLibraryofCongress ISBN:978-0-12-813235-7 ForInformationonallElsevierpublications visitourwebsiteathttps://www.elsevier.com/books-and-journals Publisher:JohnFedor AcquisitionEditor:JohnFedor EditorialProjectManager:EmilyThomson ProductionProjectManager:AnithaSivaraj Designer:MilesHitchen TypesetbyMPSLimited,Chennai,India About the Author Basant Giri received BSc and MSc degrees in Chemistry from Tribhuvan University, Kathmandu, Nepal, a second MS degree in Chemistry from the Oregon State University, Corvallis, USA, and a PhD degree in Chemistry from the University of Wyoming, Laramie, USA. After working asa research fellow at Nepal Academyof Science and Technology, Nepal for six months, Dr. Giri cofounded the Kathmandu Institute of Applied Sciences in Kathmandu, Nepal. Currently he works as a scientist at the Center for Analytical Sciences at the same institute. His research interests include development of low-cost analytical devices (e.g.,papermicrofluidics)forbiologicalandenvironmentalapplications.Hehasseveralyears of teaching experience at high school, undergraduate, and graduate levels in Nepal and the United States as faculty and teaching assistant, respectively. Dr. Giri has authored and coauthored a textbook on Nanoscience and Nanotechnology and several peer-reviewed researcharticles. xiii Preface Considering the increasing interest in microfluidics, Laboratory Methods in Microfluidics aimstofilltheneedforalaboratorybookinthisfield. Microfluidics is becoming an increasingly popular subject both in education and research. Many universities are now incorporating microfluidics in their courses to a greater or lesser extentalong with experiments in the laboratorycourses.Even though there are sev- eral textbooks covering this topic, there is currently no resource covering experimental pro- cedures. This laboratory book aims to provide a number of detailed instructions for experimentsinmicrofluidicsintendedforundergraduateandpostgraduatecoursesinanalyt- ical chemistry, biochemistry, microbiology, biotechnology, environmental science, and engi- neering. Some experiments can even be implemented in high-school curriculum projects andexperiments. Most of the experiments described in this book have been adapted from research articles and the experience of the author while teaching undergraduate analytical chemistry labs. While care has been taken to ensure that the information in this book is correct, neither the author nor the publisher can accept responsibility for the outcome of the experimental pro- cedures outlined in this book if not properly followed. The main aim of the book is to serve as an educational tool to prepare today’s students for the more demanding regimen of microfluidics. The experiments aimtoprovide practicalexperiencein the application ofclas- sical and instrumental techniques incorporated in microfluidics. Each experiment includes background information including learning objectives and an overview of the principles behind the experiment, a list of materials and chemicals required, safety notes, step-by-step procedure, additional notes to instructor, assessment questions, and recommendations for further reading. The instructions for the experiments are so detailed that the measurements can, for the most part, be taken without the help of additional literature. With Laboratory Methods in Microfluidics instructors no longer have to refer to many journals and books to find the right procedures for their experiments. It is assumed that students are familiar with basic laboratory techniques and procedures in science before starting experiments described inthisbook.However,somebasicpracticesarecoveredintheAppendix. In conclusion, this book is a work in progress, and I encourage readers to submit ideas, suggestions, and comments for improvements or for new experiments. I hope you find this laboratory manualhelpfulinyourstudy. xv xvi Preface Key features (cid:129) 18Standalone fine-tunedexperiments (cid:129) Emphasizesfabricationofmicrofluidic devicesandtheirandapplications (cid:129) Experimentsusingcommonlyfoundmaterialstominimizethecost (cid:129) Assessment questionsforeachexperiment (cid:129) Appropriateillustrationsforeachexperiment (cid:129) Additionalnotesforinstructorsallowingthemtocustomizetheexperiments (cid:129) Usefulinformationaboutpreparationoflaboratoryreagentsinappendices BasantGiri January,2017 Acknowledgments I am thankful to Dr. Harish Subedi of Western Nebraska Community College, Nebraska, Dr. Basu Panthi of Trinity University, Texas, and Dr. Lekh Adhikari of Rappahannock Community College, Virginia for providing input on the initial draft of this book. Likewise, I am thankful to Dr. Susma Giri (my wife), Mr. Ankit Pandeya, and Mr. Sagar Rayamajhi of KathmanduInstitute ofAppliedSciences,Nepalforproofreadingthemanuscript. I am grateful to my PhD advisor Dr. Debashis Dutta from the University of Wyoming, who introduced me tothefieldofmicrofluidics. Dr. TristanKinde of Sinclair Oil Corporation (then graduate student at Dutta group) helped me fabricate the glass microfluidic device during my early days as a PhD student. The lab methods described in this book such as fab- rication of glass microfluidic device, enzyme assay, and microfluidic separation were initially developedforaninstrumentalanalysiscoursebyDuttaLabatUniversityofWyoming. I express my love and gratitude to my father Krishna and mother Dwarika for their love, support,patience,andsacrifice. xvii 1 Introduction to Microfluidics 1.1 Background The field of microfluidics has been gaining popularity in the scientific community since its jumpstart about three decades ago. This multidisciplinary field has become a unique plat- form for chemistry, physics, biology, materials science, fluid mechanics, and engineering disciplines in terms of understanding both fundamentals and applications. Two other terms related to microfluidics are lab-on-a-chip and micrototal analysis systems, popularly known as μ-TAS. It is important to learn microfluidic experiments considering their potential in analytical applications and their advantages over conventional analytical systems. Incorporating microfluidics in teaching laboratories enables learning opportunities for undergraduate andgraduate students,evenhighschoolstudentsandindependentresearch- ers. As microfluidics require less amount of chemicals/reagents and generate less waste, universitiescouldreduce thecostrelatedtochemicalsandwastedisposal. 1.1.1 What is Microfluidics? Microfluidics is the science that deals with the precise control and manipulation of small volumes of fluids in network of microchannels. Generally, micro means one of the following features: small volumes (μL, nL, pL, fL) and small size leading to low energy consumption and special microdomain effects. Small size means at least one dimension of the channel must be in the range of micrometers. The behavior of fluids at microscale can differ from macroscale behavior. Factors such as surface tension, energy dissipation, and fluidic resis- tance start to dominate the system at micro level. A microfluidic chip or device contains a network of microchannels, which are connected to the outside of the channel by inputs and outputs pierced through the chip. Such connections serve as an interface between the macro- and microworld. Through these holes, the liquids or gas are injected and removed from the microfluidic chip. The small size of microfluidic devices offers several advantages including less sample and reagent consumption, low cost, short analysis time, portability, etc.1 Microfluidic technologies are not just for education and research. These technologies have now been incorporated into many commercial products. Inkjet printheads are an example of the most successful application of microfluidics.2 Printers used to reproduce digitalimagesproducedbycomputerscommonlyusesuch inkjet printers.Othercommercial products basedonmicrofluidicsinclude: 1. Agilentbioanalyzer:Thebioanalyzerinstrumentprovidesplatformforbioassays,based onelectrophoresisandflowcytometry,ofDNA,RNA,proteinsandcellswithlessthan fourmicrolitersofsample.3 LaboratoryMethodsinMicrofluidics.DOI:http://dx.doi.org/10.1016/B978-0-12-813235-7.00001-5 1 ©2017ElsevierInc.Allrightsreserved. 2 LABORATORYMETHODSINMICROFLUIDICS 2. HPLC-Chip/MSsystem:Produced byAgilentthissystemisbasedonmicrofluidicchip technologyandisdesignedfornanosprayliquidchromatography/massspectrometry (LC/MS).Accordingtothemanufacturer,thissystemisrobust,reliable,sensitive,and easytouseforbiomarkerdiscoveryandvalidation,monoclonal antibody characterization,small-moleculeanalysis,phosphopeptideanalysis,etc.4 3. Caliper LabChip platforms: Caliper of the PerkinElmer company has produced a number of LabChip devices/kits5 based on microfluidics involving both electrokinetic and pressure-driven flows. These devices can be used in bioassays for drug discovery applications such as small-molecule screening, fragment based screening, target specificity profiling, etc. The genomic DNA LabChip is used for DNA analysis.6 4. Point-of-carebloodanalyzersandothermedicaldiagnosticplatformsfromcompanies including7Abaxis,Abbott,Achiralabs,Biosite,Biovitesse,Biolithic,Baebies,Boston Microfluidics,CardioMEMS,GenePOC,FluidMedix,Micro2Gen,Nanosphere, Nanomix,etc. 1.2 Frequently Used Microfluidic Terms 1.2.1 Laminar Flow One of the important properties of fluid flow in the microdomain is laminar flow. In laminar or streamline flow, fluids flow side-by-side in parallel layers and do not necessarily mix unlike in turbulent type flow. Adjacent layers slide past one another like playing cards. The only mixing in laminar flow is through diffusion. Laminar flow is characterized by high- momentumdiffusionandlow-momentum convection.Innonscientificterms,laminar flowis smooth while turbulent flow is rough. Flow of water in steep river is an example of turbulent flow. Type of flow is characterized by a dimensionless parameter known as the Reynolds number (R ). In microfluidic systems, the R is usually less than 100 and the flow is consid- e e eredaslaminarflow8(Fig.1.1). FIGURE1.1 Schematicsoflaminarflowandturbulentflow. Chapter1(cid:129)IntroductiontoMicrofluidics 3 1.2.2 Electroosmosis and Electrophoresis These two phenomena occur when electric field is applied across the terminals of a micro- channelcontainingfluid. When electric field is applied across the two terminals of a microchannel, the bulk of the liquid inside the channel moves from one pole to the other. This motion of fluid is called electroosmotic flow (EOF), synonymously called electroosmosis (see Fig. 1.2). The velocity of thisfluidflowdependsontheappliedvoltage,microchannelmaterial,andnatureofthefluid itself. When polar liquid such as water is brought into contact into the surface of the micro- channel, the microchannel surface acquires an electric charge with a thin layer of charges very close to the surface, which is known as electric double layer. When an electric field is applied to the fluid via electrodes placed at inlets and outlets, the net charge in the double layeris induced tomove bytheresultingCoulombforce. Inanegatively charged microchan- nel surface, the EOF is directed toward the negatively charged cathode through the microchannel.8 The EOF velocity (ν ) in cm/s depends on applied electric field (E) and can be calcu- EOF lated using Eq. (1.1). Electric field in V/cm is the applied voltage per unit length of the channel. ν 5E(cid:1)μ ð1:1Þ EOF EOF where μ is the electroosmotic mobility, which depends on the device material and buffer EOF solutionandisdefinedby: Eζ μ 5 ð1:2Þ EOF η where ζ is the zeta potential of the channel wall, E is the relative permittivity of the buffer solution, and η is the viscosity of the fluid. Experimentally, ν can be determined by mea- EOF suring the retention time of a neutral analyte in a channel (see Chapter 5: Determination of FIGURE1.2 (A)AschematicdescribingEOFandEP.Whenelectricfieldisappliedacrossthetwoterminalsofa channel,negativelychargedanalytesmigratetowardanodewithEPandbulkfluidmovingtowardcathodewith EOF.ThenetflowvelocityoftheanalyteisacompromisebetweenEOFandEP.(B)Variousforcesactingupona chargedparticleundertheinfluenceofappliedelectricfield.
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