Develop a point-of-care HIV drug resistance test to assist clinicians in identifying most effective antiretroviral treatment (ART) plan
Background and Significance
Most HIV-infected individuals live in low-/middle-income countries where access to well-equipped labs is limited. OLA is an economical assay for detecting drug-resistant HIV, however, the current laboratory test is too complex to be adopted in low-resource settings. To expand access, OLA must be re-engineered into a simple point-of-care format.
Current state of OLA-Simple
Several areas of the OLA are being re-engineered, using sophisticated chemistry and physics principles to enable a sensitive, easy-to-use, and inexpensive test:
1) Dried reagent platform for long-term stability in sub-optimal conditions
2) Isothermal molecular assay to eliminate the need for expensive equipment
3) On-paper multiplexed detection of drug-resistant HIV
Lab in a phone call
Develop technology that enables cellphone audio to control flow and detect analytes in a microfluidic channel, both essential components of analytical test
Vision - Flow control
Network of microfluidic channels that respond selectively to cellphone audio tones can be used to perform sequential delivery of reagents, a requirement to perform complex bioanalytical assays.
Vision - Analyte detection
Resonance frequency of a microfluidic channel with deformable features is related to the physical properties, such as density, viscosity, or compressibility, of the fluid in the channel. Analyte-mediated changes in these properties can be measured as shift in resonance frequency using tiny optical sensor. Coagulation and catalase-based bubble formation assays are being investigated
Top left shows a series RLC resonant device containing a channel ending in a deformable diaphragm and driven by a piezo buzzer on the other end. Oscillating flow magnitude and phase in the channel is measured for a range of actuation frequencies. At resonance, flow magnitude is maximum and flow phase is zero compared to actuation signal, just like in a classic electrical resonant circuit.
TB urine test
Detection of tuberculosis cell-free DNA (cfDNA) in urine by sequence-specific capture
A quick and simple TB urine test for all patients
TB is the leading cause of infectious disease death worldwide, largely due to insufficiencies in its diagnosis. We hope to enable TB diagnosis across a wider range of patients (particularly children and HIV co-infected individuals) by testing urine, rather than sputum. Urine contains short, cell-free DNA (cfDNA) fragments generated from dying TB bacteria. By pairing sequence-specific hybridization capture of cfDNA with amplification designs for ultra-short targets, our goal is to improve the clinical sensitivity of TB diagnosis from urine. In the future, we aim to develop a TB urine test simple enough for use in low resource settings.
Current state: Assay optimization, clinical testing, and translation to simplified format
Our hybridization capture method is capable of reliably detecting down to 10 copies of a 25 bp cfDNA fragment per mL of urine, an improvement over both the sensitivity and lower fragment length limit of alternate silica-based methods. We are now testing hybridization capture with clinical samples from TB patients, while continuing assay improvements to push the lower limits of cfDNA detection in urine. We have begun moving towards a simplified format by integrating dried reagents, less costly streptavidin substrates, and isothermal amplification into the hybridization capture assay.
Acute HIV detection
Point of care diagnostic for acute HIV in low resource settings
Significance and Background
Providing a diagnostic device for HIV to developing areas according to WHO criteria for diagnostics
WHO require point of care devices to fit ASSURED criteria: Affordable, Sensitive, Specific, User-friendly, Rapid and Robust, Equipment-free, and Delivered to those who need it. Our lab is working on detection of the HIV-associated p24 antigen, which allows for detection up to ten days prior to detection by human host antibodies; we do not have to wait for the infected patient's immune response to detect HIV.
Our first prototype for the device was printed last spring. Currently we are doing testing flow properties and developing the p24 assay in a bench format. This is all in preparation of actual device testing and implementation of dehydrated chemicals in the coming months.
Cellphone-based coagulation monitor
Development of technology that enables patients on anticoagulants to use their cell phones and disposable microfluidic chips to monitor their coagulation activity
Improving access to coagulation monitoring for the millions needing it
Ubiquitous technology to allow patients to avoid having to go to labs to perform clotting tests. Instead, they can conveniently use their cell phones and disposable microfluidic chips—allowing them to save money and obtain faster results.
Models and Simulations
We are currently modeling our system in MATLAB to study the correlations between resonant frequency changes and fluid physical property changes. Preliminary experiments have been performed using chitosan gelation to simulate blood coagulation.