In liver transplantation, high overall fat content in donor livers contributes to poor graft function and lower patient outcomes. Currently, the surgeon’s impression is the main method for evaluating donor livers for fat. Since this is highly subjective, our lab is exploring a more objective method using ultrasound, specifically by measuring acoustic attenuation, which has previously been linked to fat content. This research project is focused on evaluating different output configurations of an acoustic caliper device to determine the optimal settings for measuring acoustic attenuation. The device includes transmit and receive transducers on opposite ends of a caliper and a gauge for measuring the distance between the transducer heads. Using LabVIEW, different waveform pulses can be applied at different frequencies from the transmit transducer through a sample. The transmitted signal is collected by the receive transducer at the other end of the sample. Acoustic attenuation is then estimated as the amount of signal loss in a sample relative to a reference measurement in water, which has negligible attenuation. Signal processing calculations were performed in MATLAB. This study evaluated the performance of two waveform types (chirped pulses and sinusoidal pulses) for measuring attenuation from 0.5 – 5 MHz in samples with thicknesses ranging from 15 – 50 mm. Measurements were performed in both a homogenous attenuation phantom and an inhomogeneous phantom that more closely mimics real tissue. For each phantom, waveform type, and measurement distance, attenuation measurements were repeated five times and the resulting data were analyzed statistically. Ongoing efforts with data collection and analysis will provide a basis for determining the most useful acoustic outputs for making accurate and repeatable attenuation measurements of tissue samples under ex vivo and in vivo conditions. 

The World Health Organization (WHO) reported in 2013 that approximately 35 million people in the world were infected with HIV/AIDS, and many of these individuals lived in low and middle income countries. Many women in these countries lack access to STD prevention methods, and are at high risk of HIV infection. Therefore, an affordable solution that provides rapid protection for these women is necessary. In this research, we describe a topical drug delivery platform consisting of nanofibers fabricated by the electrospinning process. The goal of this study was to fabricate drug-eluting nanofibers with tunable mechanical properties and drug release rates, two crucial properties for designing an effective drug delivery platform. We investigated the effect of electrospinning polymer blends of agarose (AGR), a natural-occurring polysaccharide, with polyvinyl alcohol (PVA). We hypothesized that AGR can provide sufficient mechanical strength to the fiber and can slow the drug release rate from PVA. We studied the effects of dimethyl sulfoxide (DMSO, an organic solvent) and tetrabutyl ammonium bromide (TBAB, an organic salt) with respect to overall AGR content in the blended fibers. Furthermore, we correlated the physiochemical properties of the nanofibers with their mechanical properties and drug release rate. Results showed that fiber morphology ad strength changed significantly with the presence of DMSO and TBAB. After further optimization of the fiber structure and mechanical properties, the hydrophilic nucleotide reverse transcriptase inhibitor tenofovir (TFV) was loaded into PVA-AGR fibers without organic solvent or additives. In-vitro release studies show that TFV burst release from the nanofibers with 80% of the TFV being released within 2 minutes. In general, fabrication and characterization of PVA-AGR-TFV nanofibers provides new insight to the use of drug-eluting fibers as a delivery platform to protect women at risk of HIV infection. 

Approximately 35.3 million people are infected with HIV worldwide, and millions more are infected every year. In the areas with the greatest burden of disease, women are disproportionately represented among those infected. Currently, no clinically available vaccine exists for HIV, though it is a heavily researched topic. Since HIV is most often acquired through a mucosal surface, any feasible vaccine would need to elicit a strong mucosal immune response. Past studies have shown that mucosally administered vaccines tend to be most effective at creating this response. However, unformulated vaccines are limited by their inability to efficiently diffuse through the vaginal epithelium. Therefore, there is a clinical need for engineered biomaterial drug delivery systems that can efficiently deliver an intravaginally administered vaccine. To investigate such a system, we have created and characterized an IgG-decorated nanoparticle vaccine delivery system designed to interact with the epithelial surface receptor FcRn. When it binds FcRn, IgG is moved from one side of the epithelium to the other in a process called transcytosis. We hypothesize that this same transcytosis system may be used to deliver an IgG-coated nanoparticle. IgG was passively absorbed onto dye-loaded polystyrene nanoparticles, which were then characterized by dynamic light scattering. Further characterization was carried out using flow cytometry methods to determine the amount of IgG on the surface of the particles as well as the functionality of the bound IgG. Modified particles were then intravaginally administered in a mouse model so that nanoparticle biodistribution and cellular uptake could be assessed. These studies have demonstrated that IgG modification improves nanoparticle trafficking to lymph nodes, a necessary destination for a vaccine to be successful. This promising result highlights the potential use of the FcRn transcytosis mechanism for intravaginal vaccine delivery.

The treatment of a variety of neurological diseases is impaired or prevented by poor drug delivery through the blood-brain barrier (BBB). A variety of compounds are able to bypass the BBB and distribute into the brain when placed at the cribriform plate by intranasal administration. In this study we investigated the ability of albumin, a known drug carrier that cannot pass the BBB, to distribute into the brain after intranasal administration. We labeled bovine serum albumin with iodine-125 ([¹²⁵I]Alb) and measured its uptake into 11 brain regions and blood serum over time (5 minutes to 6 hours). [¹²⁵I]Alb was present throughout the brain at 5 minutes. Moreover, several regions showed distinct peaks in uptake that ranged from 5 minutes (parietal cortex) to 60 minutes (midbrain). The highest levels occurred in the olfactory bulb and striatum. Roughly 2 – 4% of intranasally administered [¹²⁵I]Alb entered the bloodstream. Uptake was selectively increased into the olfactory bulb and cortex by the fluid-phase stimulator PMA (phorbol 12-myristate 13-acetate). Inhibitors to receptor-mediated transcytosis, caveolae and phosphoinositide 3-kinase, were without effect. Albumin altered the uptake of radioactive leptin given by intranasal administration, by increasing leptin uptake in the hypothalamus and decreasing it in the cerebellum and blood. We conclude that intranasal administration of [¹²⁵I]Alb reaches the brain by a mechanism that may involve fluid-phase transcytosis. Furthermore, as illustrated by leptin, albumin can affect the delivery of other substances to the brain after intranasal administration.

Upper respiratory infections are often diagnosed by nasal swabbing. This is generally done in a clinic, where the sample collected by a medical professional is analyzed in a laboratory. Nasal swabbing is also an ideal way to collect a sample for a point-of-care diagnostic as it is non-invasive and can be performed by the patient. This is especially useful in low-resource settings because a coupled point-of-care diagnostic with a nasal swab is non-invasive, low-cost and user friendly. However, nasal swabbing as a process is poorly defined, and this introduces variability in the sample collected by the patient or medical professional. In order to effectively couple nasal swabbing with point-of-care diagnostics, we need to obtain a relatively reliable sample in terms of pathogen amount. To achieve this, better characterization of the nasal swabbing process is needed. Therefore, a model of the nose will be created and made to simulate a human nose. User-studies will be performed on this model, looking at variability under the current standard for swabbing and looking to alter these techniques to procure (a) more consistent samples and (b) a higher pathogen count after sampling. These changes will increase the robustness of these point-of-care diagnostics.

Currently, rapid point-of-care diagnostics for influenza (flu) commonly lack either sensitivity or a straightforward, user-friendly interface. The Yager Lab makes point-of-care medical testing more affordable and accessible by creating easy-to-use, paper-based diagnostics. The diagnostic test we are incorporating into our devices is an immunoassay stack that consist of antibodies with specific head-binding regions and gold nanoparticles. In the presence of the target protein, a capture antibody will bind to the target protein, which then will bind a biotinylated detecting antibody and streptavidin-conjugated gold. Binding of gold nanoparticles creates a visible red marker at the detection site. In order to deliver reagents to a detection site without user intervention, we have developed paper valves that activate after a certain time and change the contact—and consequently the fluid flow—between two pieces of material. Additionally, the variations in capillary flow behavior among different materials allow us to control the movement of fluid within these paper-based devices. These methods provide means of performing more complex immunoassays on paper, thus increasing detection power without the use of electricity. Most importantly, a reduction in user steps would make diagnostic technology more accessible for at home use, airports, and low-resource settings as less training is required to use them. Utilizing the Yager Lab's current knowledge of paper valving, we are creating a device that, with minimal user interaction, detects influenza nucleoproteins, a protein that resides within the influenza virus. Detecting nucleoproteins enables us to identify the type of influenza virus, if any, that is present in a sample of fluid. Although my work only considers influenza nucleoprotein immunoassays using gold nanoparticles, the blueprint produced from this project will be adaptable for the detection of other pathogens. This work provides a means to help create rapid and affordable diagnostics for the promotion of public health.

Point-of-care (POC) diagnostic devices utilizing cell phone technology are currently in development to service gaps in healthcare and aid in the early diagnosis of disease. In particular, devices utilizing lateral flow have shown promise, although obstacles arise during analysis. Current analysis techniques lack sensitivity and specificity because they assume an ideal test line output, an unrealistic result with current technologies. Therefore, there is a need for an algorithm that can overcome irregular effects and produce a reliable and consistent output for a positive or negative test. This report demonstrates the design of an algorithm for improving interpretation of irregular test line outputs in paper-based diagnostic tests. This algorithm was integrated into a mobile app to improve analysis of POC diagnostics utilizing colorimetric outputs.