2016-2017

Digital Microfluidics for Chemistry, Biology, and Medicine

Digital microfluidics is a fluid-handling technique in which droplets are manipulated by electrostatic forces on an array of electrodes coated with a hydrophobic insulator. In contrast to the more common format of microchannel-based fluidics, digital microfluidics is uniquely well-suited for carrying out sequential chemical processing steps in multiple samples in parallel. This talk will cover my group's recent work applying digital microfluidics to problems in chemistry, biology, and medicine, including organic synthesis and integrated analysis, integrated cell culture and evaluation, and point-of-care diagnostics in resource-limited settings These examples and others suggest that digital microfluidics is emerging as a useful new tool for sample preparation and analysis, and may eventually play an important role in the next generation of laboratory methods, across many different disciplines.

Interstitial fluid flow and the cellular tumor microenvironment: effects on invasion and therapeutic outcomes

Glioblastoma, the deadliest form of brain cancer, is defined by the invasive nature of its cells. Invasion in the brain follows distinctive routes that correlate with interstitial and bulk flow pathways. In brain cancer, increased interstitial fluid flow develops due to the increase in interstitial pressure in the tumor bulk interfacing with the relatively normal pressure of the surrounding brain tissue. This differential leads to fluid transport specifically across the invasive edge of the tumor where cells are prone to both interact with the surrounding brain tissue and to evade localized, transport-limited therapies. In vitro, we have found that interstitial flow can enhance invasion of brain cancer cells using both cell lines and patient-derived glioma stem cells in tissue-engineered models of the brain-tumor interface. These effects are mediated simultaneously by both chemotactic and mechanotransduction mechanisms. In vivo, we have seen interstitial flow both correlate and increase invasion of implanted cancer cells through the brain. By conducting in vivo measurements of interstitial flow, using MRI techniques, we have seen correlations between interstitial fluid flow and patterns of glial activation, extracellular matrix deposition, and receptor activation in tumor-associated brain along these invasive pathways. These findings further implicate interstitial fluid flow as a driver of tissue morphology and indicate multiple mechanisms through which fluid flow can mediate cellular invasion and therapeutic outcomes.

Integrating Sample Preparation and Sensing for Bio/Chemical Analytics and Diagnostics

One of the continuing promises of microsystems is the capability to move diagnostics away from the central lab and into field-based applications, including point-of-care diagnostics. However, to be used away from the central lab – especially in point-of-care diagnostics – the approach must truly be sample-to-answer, i.e., no manual intervention steps and no precise manipulations. Two technologies will be presented that have followed this approach to sensing and diagnostics. First, we will review the capabilities of inkjet-fabricated paper surface enhanced Raman spectroscopy (P-SERS) devices as chemical and biological sensors. The fabrication of paper-based fluidic SERS devices using low-cost commercial inkjet printers will be introduced. We will then review results for chemical detection with paper SERS devices, including the use of the paper substrates as swabs and dipsticks for sample collection and detection, as well as chromatography SERS for sample preparation and detection in applications removed from the central lab. Examples include the detection of melamine in infant formula and therapeutic drug monitoring at the point-of-care. Second, we will review a streamlined approach to nucleic-acid-based molecular diagnostics by amplifying DNA directly from the sample preparation material (direct PCR). Microparticles functionalized with the cationic biopolymer chitosan are utilized to lyse cells, bind DNA during removal of PCR inhibitors, and transfer the DNA to the PCR reaction. Amplification of human genomic DNA from whole blood with unprecedented simplicity will be presented.

Microfluidics for Mapping Epigenomes in the World of Precision Medicine

Precision medicine requires comprehensive analysis of the molecular drivers of a disease for individual patients and use of the information to devise therapeutic procedures. In the post-genome era, such analysis benefits tremendously from decreasing cost of next-generation sequencing and improvement in big data processing. However, critical technical barrier still exists for establishing genome-wide profiles using tiny amounts of samples extracted from patients and lab animals. In this seminar, I will discuss our efforts on using microfluidics as a versatile platform for profiling epigenomes based on a low number of cells in the context of precision medicine. The epigenome turns on and off genes in a highly dynamic fashion during normal development and diseases, forming another layer of regulation on top of gene sequence. We developed MOWChIP-seq to profile histone modifications using as few as 100 cells (2015 Nature Methods). More recently, we developed microfluidic assays to probe genome-wide DNA methylation. I will discuss our studies of cell-type specific epigenomic landscapes in the context of stem cell differentiation and brain functions using these tools. These new technologies will generate insights into disease processes and help create personalized treatment strategies.

Can microfluidic flow-based diagnostics personalize therapy in sickle cell disease?: A vision for the future

This is a historic moment in sickle cell discovery with the largest pipeline of promising SCD-specific drugs in preclinical and clinical trials in the history of the disease. Despite this, there is no clinical standard for assessing erythrocyte adhesion. Dr. Hines has used flow adhesion models to understand the adhesive properties of sickle erythrocytes in a simulated blood flow environment and has worked to standardize this process for clinical testing. He recently founded Functional Fluidics, a startup company which has deployed a standardized microfluidic flow-based test into the preclinical and clinical research market. Dr. Hines will discuss advances in microfluidic flow-based blood function testing, the role these tests are play in preclinical drug validation, and the potential for applications in sickle cell clinical trials and ultimately clinical therapy.