Microfluidic-based continuous self-assembly, alignment, and printing of oligopeptides with π-conjugated cores accompanied by advanced single molecule characterization

directed assembly;optoelectronic materials;biomimetic materials;microfluidics;peptide aggregation;self-assembly;molecular dynamics;fluorescence correlation spectroscopy;nano Fourier transform infrared spectroscopy;apertureless scanning near field optical microscopy;conductive probe atomic force microscopy

Valverde, Lawrence Rene

关键词: directed assembly;    optoelectronic materials;    biomimetic materials;    microfluidics;    peptide aggregation;    self-assembly;    molecular dynamics;    fluorescence correlation spectroscopy;    nano Fourier transform infrared spectroscopy;    apertureless scanning near field optical microscopy;    conductive probe atomic force microscopy;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/100893/VALVERDE-DISSERTATION-2018.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Organicsemiconductingmaterialsexistinanimmenseandcomplexspace that,despite decadesofextensiveexploration,stillhasunexploredregionswithexcitingpotential.The mysteries of this science lie in the myriad combinations in which organic building blocks can be arranged and how these geometric conditions impact the bulk electronic properties of materials. Furthermore, the ability to physically manipulate reactants via intelligently engineered extensional flows has presented interesting avenues for control in directed assembly of biomimetic materials. Severalyearsago,we begantoapply thesenewmicrofluidictechniquestoanewclassof functionalized peptides. Soon after its inception, I took over that work and have continued efforts tooptimizedevicesandhonethetechniquesoftheiruseinordertocreateaplatformforhigh-throughput production of exceptionally aligned oligomer fibers. Early efforts have suggested that theoptoelectronicpropertiesofthesealignedmaterialsdiffersignificantlyandadvantageously from their quiescently assembled analogs. Having developed a method for continuous assembly of oligopeptide, I sought collaboration with members of the Mechanical Engineering department to investigate the next step toward using these aligned materials in advanced functional devices, continuousprintingandaligneddeposition.Wehaveachievedpreliminaryresultswithboth continuous-lineanddotprintingwithmicroscopicresolutionthatdemonstratethepotentialfor optimizing printing techniques once specific device applications for these materials are determined.In collaboration with peers in both the Materials Science and Engineering and Chemical Engineering departments, I simultaneously turned to characterizing three aspects of these materials with the goal of ultimately comparing quiescently assembled material to its aligned counterparts assembledinflow.Oneproject was gearedtowardunderstandingthekineticsof the material’s self-assemblyreactionthroughtheuseoffluorescencecorrelationmicroscopy. I measured fluctuations in fluorescence of a stimulated femtovolume to calculate diffusion constants, and thus particlesizeasafunctionoftimeduringreaction.Wecorrelatedthesefindingswithmolecular dynamicssimulationstogainsurprisinginsightintotheearlytimescalesofthesereactions.In short, it was discovered that the hitherto used method of acid-mediated self-assembly for creating functionalpeptidefibersoperatesinapre-nucleatedregimeand,infact,theearlystagesof assembly begin independent of protonation at concentrations as low as 100 nM, but no lower than10 nM.Second, I utilized arecentlydevelopednearfieldopticalmicroscopysystemtoconductnanoFourier transform infrared spectroscopyat sub-diffraction-limited spatial resolution, probing structural detailsandoptoelectronicpropertiesofseveralbiohybridmaterials atthesingle fibril level. We can identify infrared absorption features corresponding molecular secondary structure, andthecalculationofcomplexindicesofrefractionanddielectricconstantsforthesematerials should be a facile operation with the collected data.Third, I used conductiveprobeatomicforcemicroscopytechniques inconjunctionwith lithographic techniques for single-molecule transistor architectures to characterize charge carrier transport and other optoeletronic properties.Finally, through collaboration with peers conducting tangential research on the same biomimetic materials, I used optical fluorescence microscopy to characterizefluorescencespectraandpolarizationmacroscopicallyalignedpeptidefibers.This body of work on microfluidic device and printer fabrication along with detailed characterizations can help to inform the suitable applications for these materials in semiconductor devices.