Progress and limitations in reactive oxygen species quantitation.

Reactive oxygen species (ROS) are a set of oxygen- and nitrogen-containing radicals. They are produced from a wide range of sources. In biological contexts, cellular stress leads to an overproduction of ROS, which can lead to genetic damage and disease development. In industry, ROS are often productively used for water purification or for analyzing the possible toxicity of an industrial process. Because of their ubiquity, detection of ROS has been an analytical goal across a range of fields. To understand complicated systems and origins of ROS production, it is necessary to move from qualitative detection to quantitation. Analytical techniques that combine quantitation, high spatial and temporal resolution, and good specificity represent detection methods that can fill critical gaps in ROS research. Herein, we discuss the continued progress and limitations of fluorescence, electrochemical, and electron paramagnetic resonance detection of ROS over the last ten years, giving suggestions for the future of the field.

Colloidal stabilization of hydrophobic InSe 2D nanosheets in a model environmental aqueous solution and their impact on Shewanella oneidensis MR-1.

Semiconductor InSe 2D nanomaterials have emerged as potential photoresponsive materials for broadly distributed photodetectors and wearable electronics technologies due to their high photoresponsivity and thermal stability. This paper addresses an environmental concern about the fate of InSe 2D nanosheets when disposed and released into the environment after use. Semiconducting materials are potentially reactive and often form environmentally damaging species, for example reactive oxygen and nitrogen species, when degraded. InSe nanosheets are prepared using a semi bottom-up approach which involves a reaction between indium and selenium precursors at elevated temperature in an oxygen-free environment to prevent oxidation. InSe nanosheets are formed as a stable intermediate with micrometer-sized lateral dimensions and a few monolayer thickness. The InSe 2D nanosheets are obtained when the reaction is stopped after 30 minutes by cooling. Keeping the reaction at elevated temperature for a longer period, for example 60 minutes leads to the formation of InSe 3D nanoparticles of about 5 nm in diameter, a thermodynamically more stable form of InSe. The paper focuses on the colloidal stabilization of InSe nanosheets in an aqueous solution that contains epigallocatechin gallate (EGCG), a natural organic matter (NOM) simulant. We show that EGCG coats the surface of the hydrophobic, water-insoluble InSe nanosheets via physisorption. The formed EGCG-coated InSe nanosheets are colloidally stable in aqueous solution. While unmodified semiconducting InSe nanosheets could produce reactive oxygen species (ROS) when illuminated, our study shows low levels of ROS generation by EGCG-coated InSe nanosheets under ambient light, which might be attributed to ROS quenching by EGCG. Growth-based viability (GBV) assays show that the colloidally stable EGCG-coated InSe nanosheets adversely impact the bacterial growth of Shewanella oneidensis MR-1, an environmentally relevant Gram-negative bacterium in aqueous media. The impact on bacterial growth is driven by the EGCG coating of the nanosheets. In addition, live/dead assays show insignificant membrane damage of the Shewanella oneidensis MR-1 cells by InSe nanosheets, suggesting a weak association of EGCG-coated nanosheets with the cells. It is likely that the adverse impact of EGCG-coated nanosheets on bacterial growth is the result of increasing local concentration of EGCG either when adsorbed on the nanosheets when the nanosheets interact with the cells, or when desorbed from the EGCG-coated nanosheets to interact with the bacterial cells.

Label-Free Detection of Virus-like Particles with Surface-Enhanced Raman Spectroscopy through Analyte Localization and Polymer-Enabled Capture.

Virus detection is highly important; the last several years, since the onset of the SARS-CoV-2 pandemic, have highlighted a weakness in the field: the need for highly specialized and complex methodology for sensitive virus detection, which also manifests as sacrifices in limits of detection made to achieve simple and rapid sensing. Surface-enhanced Raman spectroscopy (SERS) has the potential to fill this gap, and two novel approaches to the development of a detection scheme are presented in this study. First, the physical entrapment of vesicular stomatitis virus (VSV) and additional virus-like particles through substrate design to localize virus analytes into SERS hotspots is explored. Then, the use of nonspecific linear polymers as affinity agents to facilitate polymer-enabled capture of the VSV for SERS detection is studied. Quantitative detection of the VSV is achieved down to 101 genetic copies per milliliter with an R2 of 0.987 using the optimized physical entrapment method. Physical entrapment of two more virus-like particles is demonstrated with electron microscopy, and distinctive SERS fingerprints are shown. This study shows great promise for the further exploration of label-free virus detection methods involving thoughtful substrate design and unconventional affinity agents.

A comprehensive trial on PFAS remediation: hemp phytoextraction and PFAS degradation in harvested plants.

Per- and polyfluoroalkyl substances (PFAS) are a class of recalcitrant, highly toxic contaminants, with limited remediation options. Phytoremediation - removal of contaminants using plants - is an inexpensive, community-friendly strategy for reducing PFAS concentrations and exposures. This project is a collaboration between the Mi'kmaq Nation, Upland Grassroots, and researchers at several institutions who conducted phytoremediation field trials using hemp to remove PFAS from soil at the former Loring Air Force base, which has now been returned to the Mi'kmaq Nation. PFAS were analyzed in paired hemp and soil samples using targeted and non-targeted analytical approaches. Additionally, we used hydrothermal liquefaction (HTL) to degrade PFAS in the harvested hemp tissue. We identified 28 PFAS in soil and found hemp uptake of 10 of these PFAS. Consistent with previous studies, hemp exhibited greater bioconcentration for carboxylic acids compared to sulfonic acids, and for shorter-chain compounds compared to longer-chain. In total, approximately 1.4 mg of PFAS was removed from the soil via uptake into hemp stems and leaves, with an approximate maximum of 2% PFAS removed from soil in the most successful area. Degradation of PFAS by HTL was nearly 100% for carboxylic acids, but a portion of sulfonic acids remained. HTL also decreased precursor PFAS and extractable organic fluorine. In conclusion, while hemp phytoremediation does not currently offer a comprehensive solution for PFAS-contaminated soil, this project has effectively reduced PFAS levels at the Loring site and underscores the importance of involving community members in research aimed at remediating their lands.

Nanoparticles and biochar with adsorbed plant growth-promoting rhizobacteria alleviate Fusarium wilt damage on tomato and watermelon.

The addition of biochars and nanoparticles with adsorbed Azotobacter vinelandii and Bacillus megaterium alleviated damage from Fusarium infection in both tomato (Solanum lycopersicum) and watermelon (Citrullus lanatus) plants. Tomato and watermelon plants were grown in greenhouse for 28 and 30 days (respectively) and were treated with either nanoparticles (chitosan-coated mesoporous silica or nanoclay) or varying biochars (biochar produced by pyrolysis, gasification and pyrogasification). Treatments with nanoparticles and biochars were applied in two variants - with or without adsorbed plant-growth promoting bacteria (PGPR). Chitosan-coated mesoporous silica nanoparticles with adsorbed bacteria increased chlorophyll content in infected tomato and watermelon plants (1.12 times and 1.63 times, respectively) to a greater extent than nanoclay with adsorbed bacteria (1.10 times and 1.38 times, respectively). However, the impact on other endpoints (viability of plant cells, phosphorus and nitrogen content, as well antioxidative status) was species-specific. In all cases, plants treated with adsorbed bacteria responded better than plants without bacteria. For example, the content of antioxidative compounds in diseased watermelon plants increased nearly 46% upon addition of Aries biochar and by approximately 52% upon addition of Aries biochar with adsorbed bacteria. The overall effect on disease suppression was due to combination of the antifungal effects of both nanoparticles (and biochars) and plant-growth promoting bacteria. These findings suggest that nanoparticles or biochars with adsorbed PGPR could be viewed as a novel and sustainable solution for management of Fusarium wilt.

Using 19F NMR to Investigate Cationic Carbon Dot Association with Per- and Polyfluoroalkyl Substances (PFAS).

There is much concern about per- and polyfluoroalkyl substances (PFAS) based on their environmental persistence and toxicity, resulting in an urgent need for remediation technologies. This study focused on determining if nanoscale polymeric carbon dots are a viable sorbent material for PFAS and developing fluorine nuclear magnetic resonance spectroscopy (19F NMR) methods to probe interactions between carbon dots and PFAS at the molecular scale. Positively charged carbon dots (PEI-CDs) were synthesized using branched polyethyleneimine to target anionic PFAS by promoting electrostatic interactions. PEI-CDs were exposed to perfluorooctanoic acid (PFOA) to assess their potential as a PFAS sorbent material. After exposure to PFOA, the average size of the PEI-CDs increased (1.6 ± 0.5 to 7.8 ± 1.8 nm) and the surface charge decreased (+38.6 ± 1.1 to +26.4 ± 0.8 mV), both of which are consistent with contaminant sorption. 19F NMR methods were developed to gain further insight into PEI-CD affinity toward PFAS without any complex sample preparation. Changes in PFOA peak intensity and chemical shift were monitored at various PEI-CD concentrations to establish binding curves and determine the chemical exchange regime. 19F NMR spectral analysis indicates slow-intermediate chemical exchange between PFOA and CDs, demonstrating a high-affinity interaction. The α-fluorine had the greatest change in chemical shift and highest affinity, suggesting electrostatic interactions are the dominant sorption mechanism. PEI-CDs demonstrated affinity for a wide range of analytes when exposed to a mixture of 24-PFAS, with a slight preference toward perfluoroalkyl sulfonates. Overall, this study shows that PEI-CDs are an effective PFAS sorbent material and establishes 19F NMR as a suitable method to screen for novel sorbent materials and elucidate interaction mechanisms.

Transformations and Environmental Impacts of Copper Zinc Tin Sulfide Nanoparticles and Thin Films.

Quaternary chalcogenide copper zinc tin sulfide (CZTS) nanoparticles are used to make the p-type absorber layer in CZTS solar cells, which are considered more benign alternatives to those based on cadmium telluride (CdTe) and less expensive than copper indium gallium selenide. CZTS has an ideal band gap and a high absorption coefficient for solar radiation, making the nanoparticles an attractive option for photovoltaic cells. In this work, we explore the toxicity of CZTS nanoparticles using an environmentally relevant bacterial model Shewanella oneidensis MR-1. This study also focuses on understanding the stability of CZTS-based thin films and their direct interaction with bacterial cells. Bacterial cell viability, stability of nanoparticles and thin films, as well as mechanisms of toxicity were evaluated using various analytical tools. The CZTS nanoparticle suspensions show significant acute toxic effects on bacterial cells, but long-term (72 h) exposure of bacterial cells to CZTS-based thin films (made from nanoparticles) do not exhibit similar detrimental impacts on bacterial viability. This result is compelling because it suggests that CZTS nanomaterials will have minimal unintended toxicity as long as they are incorporated into a stable film structure.

Recent Advances in the Development and Characterization of Electrochemical and Electrical Biosensors for Small Molecule Neurotransmitters.

Neurotransmitters act as chemical messengers, determining human physiological and psychological function, and abnormal levels of neurotransmitters are related to conditions such as Parkinson's and Alzheimer's disease. Biologically and clinically relevant concentrations of neurotransmitters are usually very low (nM), so electrochemical and electronic sensors for neurotransmitter detection play an important role in achieving sensitive and selective detection. Additionally, these sensors have the distinct advantage to potentially be wireless, miniaturized, and multichannel, providing remarkable opportunities for implantable, long-term sensing capabilities unachievable by spectroscopic or chromatographic detection methods. In this article, we will focus on advances in the development and characterization of electrochemical and electronic sensors for neurotransmitters during the last five years, identifying how the field is progressing as well as critical knowledge gaps for sensor researchers.

Platelet Response to Allergens, CXCL10, and CXCL5 in the Context of Asthma.

Asthma is a chronic respiratory disease initiated by a variety of factors, including allergens. During an asthma attack, the secretion of C-X-C-motif chemokine 10 (CXCL10) and chemokine ligand 5 (CCL5) causes the migration of immune cells, including platelets, into the lungs and airway. Platelets, which contain three classes of chemical messenger-filled granules, can secrete vasodilators (adenosine diphosphate and adenosine triphosphate), serotonin (a vasoconstrictor and a vasodilator, depending on the biological system), platelet-activating factor, N-formylmethionyl-leucyl-phenylalanine ((fMLP), a bacterial tripeptide that stimulates chemotaxis), and chemokines (CCL5, platelet factor 4 (PF4), and C-X-C-motif chemokine 12 (CXCL12)), amplifying the asthma response. The goal of this work was threefold: (1) to understand if and how the antibody immunoglobulin E (IgE), responsible for allergic reactions, affects platelet response to the common platelet activator thrombin; (2) to understand how allergen stimulation compares to thrombin stimulation; and (3) to monitor platelet response to fMLP and the chemokines CXCL10 and CCL5. Herein, high-pressure liquid chromatography with electrochemical detection and/or carbon-fiber microelectrode amperometry measured granular secretion events from platelets with and without IgE in the presence of the allergen 2,4,6-trinitrophenyl-conjugated ovalbumin (TNP-Ova), thrombin, CXCL10, or CCL5. Platelet adhesion and chemotaxis were measured using a microfluidic platform in the presence of CXCL10, CCL5, or TNP-OVA. Results indicate that IgE binding promotes δ-granule secretion in response to platelet stimulation by thrombin in bulk. Single-cell results on platelets with exogenous IgE exposure showed significant changes in the post-membrane-granule fusion behavior during chemical messenger delivery events after thrombin stimulation. In addition, TNP-Ova allergen stimulation of IgE-exposed platelets secreted serotonin to the same extent as thrombin platelet stimulation. Enhanced adhesion to endothelial cells was demonstrated by TNP-Ova stimulation. Finally, only after incubation with IgE did platelets secrete chemical messengers in response to stimulation with fMLP, CXCL10, and CCL5.

Investigation of Charged Small Molecule-Aptamer Interactions with Surface Plasmon Resonance.

Investigating the interactions between small, charged molecules and aptamers using surface plasmon resonance (SPR) is limited by the inherent low response of small molecules and difficulties with nonspecific electrostatic interactions between the aptamer, analyte, and sensor surface. However, aptamers are increasingly being used in sensors for small molecule detection in critical areas like healthcare and environmental safety. The ability to probe these interactions through simple, direct SPR assays would be greatly beneficial and allow for the development of improved sensors without the need for complicated signal enhancement. However, these assays are nearly nonexistent in the current literature and are instead surpassed by sandwich or competitive binding techniques, which require additional sample preparation and reagents. In this work, we develop a method to characterize the interaction between the charged small molecule serotonin (176 Da) and an aptamer with SPR using streptavidin-biotin capture and a high-ionic-strength buffer. Additionally, other methods, such as serotonin immobilization and thiol-coupling of the aptamer, were investigated for comparison. These techniques give insight into working with small molecules and allow for quickly adapting a binding affinity assay into a direct SPR sensor.

NanoAdventure: Development of a Text-Based Adventure Game in English, Spanish, and Chinese for Communicating about Nanotechnology and the Nanoscale.

Video games and immersive, narrative experiences are often called upon to help students understand difficult scientific concepts, such as sense of scale. However, the development of educational video games requires expertise and, frequently, a sizable budget. Here, we report on the use of an interactive text-style video game, NanoAdventure, to communicate about sense of scale and nanotechnology to the public. NanoAdventure was developed on an open-source, free-to-use platform with simple coding and enhanced with free or low-cost assets. NanoAdventure was launched in three languages (English, Spanish, Chinese) and compared to textbook-style and blog-style control texts in a randomized study. Participants answered questions on their knowledge of nanotechnology and their attitudes toward nanotechnology before and after reading one randomly assigned text (textbook, blog, or NanoAdventure game). Our results demonstrate that interactive fiction is effective in communicating about sense of scale and nanotechnology as well as the relevance of nanotechnology to a general public. NanoAdventure was found to be the most "fun" and easy to read of all text styles by participants in a randomized trial. Here, we make the case for interactive "Choose Your Own Adventure" style games as another effective tool among educational game models for chemistry and science communication.

Synthesis Processes, Photoluminescence Mechanism, and the Toxicity of Amorphous or Polymeric Carbon Dots.

Fluorescence is the emission of light following photon absorption. This optical phenomenon has many applications in daily life, such as in LED lamps, forensics, and bioimaging. Traditionally, small-molecule fluorophores were most common, but the types of molecules and particles with compelling fluorescence properties have expanded. For example, green fluorescent protein (GFP) was isolated from jellyfish and won the Nobel prize in 2008 due to its significant utility as a fluorescent biomarker. Using the intrinsic fluorescence of GFP, many previously invisible biological processes and substances can now be observed and studied. Other fluorescent materials have also been developed, greatly expanding the potential applications. Semiconductor quantum dots (QDs), which have bright fluorescence and a narrow bandwidth, are a popular choice for display technologies. However, QDs are made of heavy metal elements such as Cd and Se, which pose potential safety concerns to the environment and human health. Thus, new fluorescent organic materials are being developed to mitigate the toxicological concerns while maintaining the QD advantages.One type of new material attracting great attention as an environmentally friendly substitute for semiconductor QDs is carbon dots (CDs). CDs have been developed with strong fluorescence, good photostability, and low toxicity using a variety of precursors, and some synthesis processes have good potential for scale-up. However, since they are made of a variety of materials and through different methods, the structure and properties of CDs can differ from preparation to preparation. There are three major types of CDs: graphene quantum dots (GQDs), carbon quantum dots (CQDs), and amorphous or polymeric carbon dots (PCDs). This Account focuses on PCDs and their unique properties by comparing it with other types of CDs. The synthesis processes, fluorescence properties, fluorescence mechanisms, and toxicity are discussed below with an emphasis on the distinct attributes of PCDs.PCDs can be synthesized from small molecules or polymers. They have an amorphous or cross-linked polymer structure with bright fluorescence. This fluorescence is possibly due to cross-link-enhanced emission or clusteroluminescence that arises from the through-space interactions of heteroatomic-rich functional groups. Other fluorescence mechanisms of CDs, including distinct contributions from the carbon core and surface states, may also contribute. The toxicological profiles of CDs are influenced by the chemical composition, surface functionalization, and light illumination. CDs are generally thought to be of low toxicity, and this can be further improved by removing toxic byproducts, functionalizing the surface, and reducing light exposure to minimize the generation of reactive oxygen species.

Machine Learning-Assisted Carbon Dot Synthesis: Prediction of Emission Color and Wavelength.

Carbon dots (CDs) have attracted great attention in a range of applications due to their bright photoluminescence, high photostability, and good biocompatibility. However, it is challenging to design CDs with specific emission properties because the syntheses involve many parameters, and it is not clear how each parameter influences the CD properties. To help bridge this gap, machine learning, specifically an artificial neural network, is employed in this work to characterize the impact of synthesis parameters on and make predictions for the emission color and wavelength for CDs. The machine reveals that the choice of reaction method, purification method, and solvent relate more closely to CD emission characteristics than the reaction temperature or time, which are frequently tuned in experiments. After considering multiple models, the best performing machine learning classification model achieved an accuracy of 94% in predicting relative to actual color. In addition, hybrid (two-stage) models incorporating both color classification and an artificial neural network k-ensemble model for wavelength prediction through regression performed significantly better than either a standard artificial neural network or a single-stage artificial neural network k-ensemble regression model. The accuracy of the model predictions was evaluated against CD emission wavelengths measured from experiments, and the minimum mean average error is 25.8 nm. Overall, the models developed in this work can effectively predict the photoluminescence emission of CDs and help design CDs with targeted optical properties.

Characterization of the Presence and Function of Platelet Opioid Receptors.

Opioids are typically used for the treatment of pain related to disease or surgery. In the body, they enter the bloodstream and interact with a variety of immune and neurological cells that express the µ-, δ-, and κ-opioid receptors. One blood-borne cell-like body that is not well understood in the context of opioid interactions is the platelet. The platelet is a highly sensitive anucleate cell-like fragment responsible for maintaining hemostasis through shape change and the secretion of chemical messengers. This research characterizes platelet opioid receptors, how specific receptor agonists impact platelet exocytosis, and the role of the κ-and µ-receptors in platelet function. Platelets were found to express all three opioid receptors, but upon stimulation with their respective agonist no activation was detected. Furthermore, exposure to the opioid agonists did not impact traditional platelet secretion stimulated by thrombin, a natural platelet activator. In addition, data collected from knockout mice suggest that the opioid agonists may be interacting nonspecifically with platelets. Dark-field images revealed differences in activated platelet shape between the κ- and µ-knockout platelets and the control platelets. Finally, κ-knockout platelets showed variations in their ability to adhere and aggregate compared to control platelets. Overall, these data show that platelet function is not likely to be heavily affected by blood-borne opioids.

Unconventional aliphatic fluorophores discovered as the luminescence origin in citric acid-urea carbon dots.

Carbon dots (CDs) are emerging as the material of choice in a range of applications due to their excellent photoluminescence properties, ease of preparation from inexpensive precursors, and low toxicity. However, the precise nature of the mechanism for the fluorescence is still under debate, and several molecular fluorophores have been reported. In this work, a new blue fluorophore, 5-oxopyrrolidine-3-carboxylic acid, was discovered in carbon dots synthesized from the most commonly used precursors: citric acid and urea. The molecular product alone has demonstrated interesting aggregation-enhanced emission (AEE), making it unique compared to other fluorophores known to be generated in CDs. We propose that this molecular fluorophore is associated with a polymer backbone within the CDs, and its fluorescence behavior is largely dependent on intermolecular interactions with the polymers or other fluorophores. Thus, a new class of non-traditional fluorophores is now relevant to the consideration of the CD fluorescence mechanism, providing both an additional challenge to the community in resolving the mechanism and an opportunity for a greater range of CD design schemes and applications.

Effect of (3-aminopropyl)triethoxysilane on dissolution of silica nanoparticles synthesized via reverse micro emulsion.

Silica nanomaterials have been studied based on their potential applications in a variety of fields, including biomedicine and agriculture. A number of different molecules have been condensed onto silica nanoparticles' surfaces to present the surface chemistry needed for a given application. Among those molecules, (3-aminopropyl)triethoxysilane (APS) is one of the most commonly applied silanes used for nanoparticle surface functionalization to achieve charge reversal as well as to enable cargo loading. However, the colloidal stability of APS-functionalized silica nanoparticles has not been thoroughly studied, which can be problematic when the high reactivity of amine groups is considered. In this study, four different types of silica nanoparticles with varied location of added APS have been prepared via a reverse micro emulsion process, and their colloidal stability and dissolution behavior have been investigated. Systematic characterization has been accomplished using transmission electron microscopy (TEM), silicomolybdic acid (SMA) spectrophotometric assay, nitrogen adsorption-desorption surface area measurement, and aerosol ion mobility-mass spectrometry to track the nanoparticles' physical and chemical changes during dissolution. We find that when APS is on the interior of the silica nanoparticle, it facilitates dissolution, but when APS is condensed both on the interior and exterior, only the exterior siloxane bonds experience catalytic hydrolysis, and the interior dissolution is dramatically suppressed. The observation and analyses that silica nanoparticles show different hydrolysis behaviors dependent on the location of the functional group will be important in future design of silica nanoparticles for specific biomedical and agricultural applications.

Development of a Highly Responsive Organofluorine Temperature Sensor for 19F Magnetic Resonance Applications.

Temperature can affect many biological and chemical processes within a body. During in vivo measurements, varied temperature can impact the accurate quantification of additional abiotic factors such as oxygen. During magnetic resonance imaging (MRI) measurements, the temperature of the sample can increase with the absorption of radiofrequency energy, which needs to be well-regulated for thermal therapies and long exposure. To address this potentially confounding effect, temperature can be probed intentionally using reporter molecules to determine the temperature in vivo. This work describes a combined experimental and computational approach for the design of fluorinated molecular temperature sensors with the potential to improve the accuracy and sensitivity of 19F MRI-based temperature monitoring. These fluorinated sensors are being developed to overcome the temperature sensitivity and tissue limitations of the proton resonance frequency (10 × 10-3 ppm °C-1), a standard parameter used for temperature mapping in MRI. Here, we develop (perfluoro-[1,1'-biphenyl]-4,4'-diyl)bis((heptadecafluorodecyl)sulfane), which has a nearly 2-fold increase in temperature responsiveness, compared to the proton resonance frequency and the 19F MRI temperature sensor perfluorotributylamine, when tested under identical NMR conditions. While 19F MRI is in the early stages of translation into clinical practice, development of alternative sensors with improved diagnostic abilities will help advance the development and incorporation of fluorine magnetic resonance techniques for clinical use.

Plasmodium chabaudi Affects Mast Cell Degranulation as Measured by Carbon-Fiber Microelectrode Amperometry.

Mast cells (MCs) are effector cells of the immune system commonly known for their role in asthma and allergy. They are present throughout biological systems in various tissues, serving as an interface between the biological system and environment. Previous work characterizing the impact of malaria on MCs revealed contradictory results, showing minimal to strong correlation between MC degranulation and disease progression. This work seeks to reveal how MC degranulation is impacted in the presence of malaria, induced by Plasmodium chabaudi, using a mouse model and a single cell measurement technique that reveals exquisite biophysical detail about any impacts to the degranulation process. It was hypothesized that the malaria parasites would impact MC degranulation response during live infection, and the differences would be revealed via carbon-fiber microelectrode amperometry. In fact, the data collected show that different stages of malaria infection affect MC degranulation differently, affirming the importance of considering different infection stages in future studies of malarial immune response. Furthermore, a comparison of MC degranulation response to that measured from platelets under similar circumstances shows similar trends in quantitative degranulation, suggesting that MC and platelet exocytosis machinery are affected similarly despite their distinct biological roles. However, based on the small number of mouse replicates, the studies herein suggest that there should be further study about cellular and disease processes. Overall, the work herein reveals important details about the role of MCs in malaria progression, relevant during treatment decisions, as well as a potentially generalizable impact on chemical messenger secretion from cells during malarial progression.

Investigation of the Post-Synthetic Confinement of Fluorous Liquids Inside Mesoporous Silica Nanoparticles.

Perfluorocarbon (PFC) filled nanoparticles are increasingly being investigated for various biomedical applications. Common approaches for PFC liquid entrapment involve surfactant-based emulsification and Pickering emulsions. Alternatively, PFC liquids are capable of being entrapped inside hollow nanoparticles via a postsynthetic loading method (PSLM). While the methodology for the PSLM is straightforward, the effect each loading parameter has on the PFC entrapment has yet to be investigated. Previous work revealed incomplete filling of the hollow nanoparticles. Changing the loading parameters was expected to influence the ability of the PFC to fill the core of the nanoparticles. Hence, it would be possible to model the loading mechanism and determine the influence each factor has on PFC entrapment by tracking the change in loading yield and efficiency of PFC-filled nanoparticles. Herein, neat PFC liquid was loaded into silica nanoparticles and extracted into aqueous phases while varying the sonication time, concentration of nanoparticles, volume ratio between aqueous and fluorous phases, and pH of the extraction water. Loading yields and efficiency were determined via 19F nuclear magnetic resonance and N2 physisorption isotherms. Sonication time was indicated to have the strongest correlation to loading yield and efficiency; however, method validation revealed that the current model does not fully explain the loading capabilities of the PSLM. Confounding variables and more finely controlled parameters need to be considered to better predict the behavior and loading capacity by the PSLM and warrants further study.