Diagnostic assays created using simple and inexpensive materials have the potential to transform healthcare management systems in resource-limited settings. This change can be caused by making assays more accessible, more affordable, or by inspiring the development of tests that do not exist currently but would solve a considerable need. Microfluidic devices produced from patterned paper have emerged as a promising candidate for a general platform capable of supporting the development of these diagnostic assays.
We are interested in two aspects of paper-based microfluidics: (i) using the inherent stackability of patterned paper to develop three-dimensional microfluidic devices and (ii) expanding the role of paper in diagnostic assays.
The quantification of blood cells provides critical information about a patient's health status. We have demonstrated paper-based microfluidic devices that enable the controlled transport of red blood cells (RBCs) and the measurement of the hematocrit—the ratio of RBC packed cell volume to total volume of whole blood. The properties of paper, device treatment, and device geometry affect the overall extent and reproducibility of transport of RBCs.
Dried Blood Spot (DBS) Cards
Our patterned dried blood spot cards have the potential to permanently alter the way blood and plasma samples are collected on a global scale. Our approach will improve blood sample collection, stability, and integrity—leading to more dependable biomedical samples. Enhancing sample output provides highly accurate insight to patient health and enables personalized treatment plans.
We have developed a paper-based device architecture for performing immunoassays. This device format, intended to disrupt the decades-long monopoly that lateral flow devices have on immunoassays, can facilitate a variety of assay formats (sandwich, indirect, competitive) and sample matrices (saliva, urine, blood) with little modification. Perhaps most importantly, the fluidic pathways patterned within our devices enable combining assays together in multiplex–multiple immunoassays or multiple types of assays (e.g., for enzymes, biomarkers). We have demonstrated the development of assays for pregnancy, malaria, dengue, HIV, and Ebola, among others.
Informed Design of High Z Radiosensitizers
This group of projects is aimed at informing how nanoparticle radiosensitizers design parameters impact the therapeutic efficiency of cancer radiotherapy. High Z radiosensitizers locally amplify incident radiation through a cascade of secondary ionization events, however, it is not well understood how the ligand chemistry and composition of nanoparticle radiosensitizers impact these primary and secondary ionization events. Through several investigations, we aim to understand how nanoparticle high Z composition, geometry and ligand shell chemistries impact the low energy electron (LEE) flux and downstream radiobiological effects in malignant tissue. This interdisciplinary research program involves collaboration with Prof. Joshua A. Kritzer (Tufts University), Prof. E. Charles H. Sykes (Tufts University) and Prof. Ross Berbeco (Harvard Medical School).
Adhesion and programmed changes in adhesion play critical roles in the development, health, and pathogenesis of disease. In addition, biomaterials are often characterized by their ability to promote or resist cell adhesion. The current methods of microscopy used to observe cell adhesion are either restricted to transparent substrates or require the use of fluorescent labels.
We developed lateral microscopy to observe and quantify cell adhesion. The imaging system of the lateral microscope is oriented substantially parallel to the surface of interest, which allows cells to be observed directly on any material regardless of its composition, opacity, or topography and without the need for labels. In this way, we can use a “biological analog” to surface wettability where measurements of contact angle and the rate of change in contact angle describe cell adhesion.