Christine K. Payne

Urinary stone disease is a benign but painful health condition that affects 11% of Americans in the US. It is commonly treated with ureteroscopic laser lithotripsy, which delivers a near-infrared pulsed laser beam to break down the kidney stone. Conventionally, the advances of laser lithotripsy hinge on laser optical engineering, which enables parameter space in power, pulse profile, and repetition frequency. Meanwhile, the absorption coefficient of the fluid near and inside the stone has never been considered a tunable parameter, despite its crucial role in stone ablation and thermal injury. In this talk, I will introduce our multidisciplinary team’s recent work, which utilizes a near-infrared-absorbing nanofluid to enhance the performance and functionality of clinical laser lithotripsy. By increasing the light-matter interaction, our in vitro and in vivo tests show that nanofluid can increase the stone ablation by several folds in a self-replenishing manner without incurring thermal dose or injury, holding great potential to shift the paradigm in laser lithotripsy.

The high level of nanomaterials used in industrial and consumer products drives the need to better understand how these materials interact with biological systems. We probe the interaction of four commonly used nanomaterials; titanium dioxide, silicon dioxide, and silver nanoparticles and multi-walled carbon nanotubes, with a representative lung lining fluid lipid, L-α-phosphatidylcholine, and serum proteins. We find that the presence of the lipid increases the adsorption of fetal bovine serum on the surface of the nanomaterials. Individual serum proteins, bovine serum albumin and transferrin, show a nanomaterial-dependent response. We used murine macrophages to characterize the cellular response to lipid-protein-nanoparticle complexes and found a nanomaterial-dependent response, measured by cytokine release. In the case of titanium dioxide nanoparticles, l-α-phosphatidylcholine on the nanomaterial surface provides a protective effect against inflammation. While much recent work probes the protein corona that forms on nanomaterials used in biological applications, this work examines the lipid and protein coronas with relevance to inhalation exposures.

Urinary stone disease, characterized by the hard mineral deposits in the urinary tract, has seen a rising prevalence globally. This condition often leads to severe pain and requires medical intervention. Laser lithotripsy, a minimally invasive treatment, uses laser to fragment urinary stones to facilitate removal or natural passage. Among available laser technologies, Ho:YAG laser has established itself as the gold standard for three decades. Efforts to improve ablation efficiency have focused on laser parameters such as pulse energy and frequency. This study introduces an ablation enhancement strategy that incorporates nanoparticles with strong near-infrared absorption into the surrounding fluid to enhance light-matter interaction. Using 0.03 wt.% PEDOT:PSS nanofluid improves stone ablation efficiency by 38-727% in spot treatment and 26-75% in scanning treatment with a clinical Ho:YAG laser lithotripter. The highly absorbing nanofluid accelerates vapor tunnel formation, boosts laser energy transmission, and permeates stone pores to enhance damage, without increasing thermal tissue injury. Cytotoxicity tests also confirmed minimal toxicity at appropriate concentrations. This nanofluid-based approach offers a promising advancement for more efficient and safer laser lithotripsy. Further work should address the remaining challenges for clinical translation, including aggregation in saline, efficacy in real human kidney stones, and comprehensive animal studies.

Nanoparticles (NPs) present in any biological environment form a "corona" of proteins on the NP surface. This protein corona, rather than the bare NP, determines the biological response to the protein-NP complex. Experiments, especially proteomics, can provide an inventory of proteins in the corona, but researchers currently lack a method to predict which proteins will interact with NPs. The ability to predict the protein corona would aid the design of NPs by decreasing the time and cost of experiments. We describe the development and use of random forest regression and classification models to predict protein abundance and enrichment, respectively, on the surface of NPs using a dataset of NP, protein, and experimental features. These models were trained using data generated in-house through the synthesis and functionalization of NPs with varied core material, surface ligand, diameter, and zeta potential. NPs were incubated with fetal bovine serum, a common protein source for cultured cells, to form a corona, which was characterized by proteomics. Both models identified protein abundance in the serum used to form the corona as the most significant predictor of corona proteins. NP zeta potential and hydrodynamic diameter emerged as the most important NP factors. The random forest regression model was used to test the ability to predict the protein corona of NPs that were excluded from the training data. We highlight the best and worst predictions. These findings offer a machine learning approach to guide experiments.

The movement of intracellular cargo transported by molecular motors is commonly marked by switches between directed motion and stationary pauses. The predominant measure for assessing movement is effective diffusivity, which predicts the mean-squared displacement of particles over long timescales. In this work, we considered an alternative analysis regime that focused on shorter timescales and relied on automated segmentation of paths. Due to intrinsic uncertainty in changepoint analysis, we highlighted the importance of statistical summaries that were robust with respect to the performance of segmentation algorithms. In contrast to effective diffusivity, which averaged over multiple behaviors, we emphasized tools that highlighted the different motor-cargo states, with an eye toward identifying biophysical mechanisms that determined emergent whole-cell transport properties. By developing a Markov chain model for noisy, continuous, piecewise-linear microparticle movement, and associated mathematical analysis, we provided insight into a common question posed by experimentalists: how does the choice of observational frame rate affect what is inferred about transport properties?

The movement of intracellular cargo transported by molecular motors is commonly marked by switches between directed motion and stationary pauses. The predominant measure for assessing movement is effective diffusivity, which predicts the mean-squared displacement of particles over long time scales. In this work, we consider an alternative analysis regime that focuses on shorter time scales and relies on automated segmentation of paths. Due to intrinsic uncertainty in changepoint analysis, we highlight the importance of statistical summaries that are robust with respect to the performance of segmentation algorithms. In contrast to effective diffusivity, which averages over multiple behaviors, we emphasize tools that highlight the different motor-cargo states, with an eye toward identifying biophysical mechanisms that determine emergent whole-cell transport properties. By developing a Markov chain model for noisy, continuous, piecewise-linear microparticle movement, and associated mathematical analysis, we provide insight into a common question posed by experimentalists: how does the choice of observational frame rate affect what is inferred about transport properties?

High Resolution Image Download MS PowerPoint Slide The increasing use of multiwalled carbon nanotubes (MWCNTs) could increase the risk of allergic lung disease in occupational or consumer settings. We previously reported that MWCNTs exacerbated allergic lung disease in mice induced by extract from house dust mites (HDM), a common cause of asthma in humans. Because MWCNTs avidly bind biomolecules to form protein coronas that can modify immunotoxicity, we hypothesized that exacerbation of allergic lung disease in mice caused by coexposure to MWCNTs and HDM extract was due to the formation of an allergen corona. In a first set of experiments, male and female C57BL/6J mice were coexposed to MWCNTs and HDM extract over 3 weeks compared to MWCNTs or HDM extract alone. In a second set of experiments, mice were exposed to pristine MWCNTs or MWCNTs with an HDM allergen corona (HDM-MWCNTs). HDM-MWCNTs were formed by incubating MWCNTs with HDM extract, where ∼7% of proteins adsorbed to MWCNTs, including Der p 1 and Der p 2. At necropsy, bronchoalveolar lavage fluid was collected from lungs to assess lactate dehydrogenase, total protein and inflammatory cells, while lung tissue was used for histopathology, qPCR, and Western blotting. Compared to MWCNTs or HDM extract alone, coexposure to MWCNTs and HDM extract or exposure to HDM-MWCNTs increased pathological outcomes associated with allergic lung disease (eosinophilia, fibrosis, mucous cell metaplasia), increased mRNAs associated with fibrosis ( Col1A1, Arg1 ) and enhanced STAT6 phosphorylation in lung tissue. These findings indicated that exacerbation of HDM-induced allergic lung disease by MWCNTs is due to an allergen corona.

High Resolution Image Download MS PowerPoint Slide We encounter titanium dioxide nanoparticles (TiO 2 NPs) throughout our daily lives in the form of food coloring, cosmetics, and industrial materials. They are used on a massive industrial scale, with over 1 million metric tons in the global market. For the workers who process these materials, inhalation is a major concern. The goal of our current research is to provide a direct comparison of the three major types of TiO 2 NPs (P25, E171, R101) in terms of surface characterization, cellular response, and in vivo response following introduction into the lungs of mice. In both cellular and in vivo experiments, we observe a pro-inflammatory response to the P25 TiO 2 NPs that is not observed in the E171 or R101 TiO 2 NPs at mass-matched concentrations. Cellular experiments measured a cytokine, TNF-α, as a marker of a pro-inflammatory response. In vivo experiments in mice measured the number of immune cells and four pro-inflammatory cytokines (IL-6, MIP-2, IP-10, and MCP-1) present in bronchoalveolar lavage fluid. A detailed physical and chemical characterization of the TiO 2 NPs shows that the P25 TiO 2 NPs are distinguished by smaller primary particles suggesting that samples matched by mass contain a larger number of P25 TiO 2 NPs. Cellular dose–response measurements with the P25, E171, and R101 TiO 2 NPs support this hypothesis showing increased TNF-α release by macrophages as a function of TiO 2 NP dose. Overall, this direct comparison of the three major types of TiO 2 NPs shows that the number of particles in a dose, which is dependent on the particle diameter, is a key parameter in TiO 2 NP-induced inflammation.

Urinary stone disease, characterized by the formation of hard mineral deposits in the urinary tract, has seen a rising prevalence in the U.S. in recent years. This condition often leads to severe pain and typically requires medical intervention. Laser lithotripsy, a minimally invasive treatment, uses laser energy to fragment urinary stones into smaller pieces, facilitating easier removal or natural passage. Among available laser technologies, the holmium:yttrium-aluminum-garnet (Ho:YAG) laser has established itself as the gold standard over the past three decades. Efforts to improve Ho:YAG laser ablation efficiency have largely focused on adjusting laser parameters such as pulse energy and frequency. In this study, we proposed a nanoplasmonic engineering strategy by incorporating nanoparticles (NPs) with strong near-infrared (NIR) absorption into the fluid surrounding the stone, enhancing the light-matter interaction. Using a 0.03 wt.% PEDOT:PSS nanofluid, stone ablation efficiency improved by 38-727% in spot treatment and 26-75% in scanning treatment with a clinical laser lithotripter. The highly absorbing nanofluid accelerates vapor tunnel formation, boosts laser energy transmission to the stone, and permeates stone pores to enhance damage, without increasing thermal tissue injury risk. Cytotoxicity tests also confirmed minimal toxicity at appropriate concentrations. This nanofluid-based approach offers a promising advancement for more efficient and safer laser lithotripsy.

Autoimmune and inflammatory diseases are highly complex, limiting treatment and the development of new therapies. Recent work has shown that cell-free DNA bound to biological microparticles is linked to systemic lupus erythematosus, a prototypic autoimmune disease. However, the heterogeneity and technical challenges associated with the study of biological particles have hindered a mechanistic understanding of their role. Our goal was to develop a well-controlled DNA-particle model system to understand how DNA-particle complexes affect cells. We first characterized the adsorption of DNA on the surface of polystyrene nanoparticles (200 nm and 2 µm) using transmission electron microscopy, dynamic light scattering, and colorimetric DNA concentration assays. We found that DNA adsorbed on the surface of nanoparticles was resistant to degradation by DNase 1. Macrophage cells incubated with the DNA-nanoparticle complexes had increased production of pro-inflammatory cytokines tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6). We probed two intracellular DNA sensing pathways, toll-like receptor 9 (TLR9) and cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING), to determine how cells sense the DNA-nanoparticle complexes. We found that the cGAS-STING pathway is the primary route for the interaction between DNA-nanoparticles and macrophages. These studies provide a molecular and cellular-level understanding of DNA-nanoparticle-macrophage interactions. In addition, this work provides the mechanistic information necessary for future in vivo experiments to elucidate the role of DNA-particle interactions in autoimmune diseases, providing a unique experimental framework to develop novel therapeutic approaches.

MWCNTs are used in a variety of industrial applications. Inhalation of MWCNTs can occur during manufacturing and handling. We address the interaction of MWCNTs with house dust mite allergens (a source of asthma) and lung fluid proteins.

Background: The study of bacterial electrophysiology is important for understanding antibacterial resistance, biofilm formation, and fundamental questions of cell growth and division. These experiments require new tools to modulate the resting membrane potential of bacteria. The use of potassium and magnesium ions, antibiotics, short exposures to blue light, and electric field have been used to hyperpolarize or depolarize bacteria. Our research characterizes the cellular response to a new reagent, gold ions, using single-cell imaging. Materials and Methods: We use fluorescence microscopy to monitor, in real time, the change to the membrane potential when Bacillus subtilis ( B. subtilis ) and Escherichia coli ( E. coli ) are exposed to gold ions. Membrane potential is measured with two different Nernstian dyes, thioflavin T and tetramethylrhodamine methyl ester. Gold ions are introduced to cell by adding gold salt solutions or through the electrochemical generation of gold ions. Inductively coupled plasma mass spectrometry (ICP-MS) is used to determine the concentration of gold ions generated electrochemically. Standard growth curves are used to study the effect of gold ions on bacterial growth. Results: Single cell fluorescence imaging shows that a solution of gold ions hyperpolarizes B. subtilis and E. coli in a concentration-dependent manner. ICP-MS confirms that applied voltage and frequency controls the concentration of gold ions generated electrochemically. Electrochemically generated gold ions diffuse through the imaging chamber creating a wave of hyperpolarization. The speed of the hyperpolarization wave can be modulated by voltage and frequency. Conclusions: Our research describes a new tool, gold ions, for the hyperpolarization of bacteria. Gold ions can be introduced to bacteria as a salt solution or generated electrochemically, providing spatial and temporal control of bacterial membrane potential. Beyond this work, it is possible that hyperpolarization may play a role in the use of gold as an antibacterial agent.

nanoparticles or coronas formed from serum or albumin. These experiments show that understanding the concentration and composition of the protein corona is essential for understanding the pulmonary response associated with human exposure to nanoparticles.