Electrospray-Differential Mobility Analysis of Bionanoparticles

The growth of the multibillion dollar bionanoparticle industry has spurred the development of new physical characterization methods. One such method, electrospray-differential mobility analysis (ES-DMA) constitutes an electrospray for aerosolization of bionanoparticles (such as viruses, gold-nanoparticles, proteins, nanoparticle-protein complexes) and an ion mobility method that operates at atmospheric conditions, and separates bionanoparticles spatially. This dissertation identifies some relevant "problem" areas for ES-DMA by reviewing selected applications. Some such problems are: proteins while passing through ES capillaries are found to interact with it and thus produce time dependent size distributions. Further, it is thought that adsorbed proteins may subsequently desorb and influence size distributions with the ES-DMA which may concomitantly affect quantification of aggregates. These artifacts are studied systematically and it is demonstrated that ES-DMA can quantify adsorption-desorption of complex protein mixtures at high shear rates. Further, it is shown that desorbing proteins do not have a significant effect on size distributions. Another artifact of the ES takes place during the aersolization process. Two units (called monomers) of a bionanoparticle may get encapsulated in the same ES droplet and upon drying of the droplet create artificial dimers thus affecting quantification with ES-DMA. Assuming Poisson distribution, this thesis provides a systematic approach that can be undertaken to eliminate this artifact. A third artifact arises from the low sensitivity of the DMA to size increase. When a ligand (for e.g. protein) adsorbs to a bionanoparticle it creates an increase in the size of the later, which can be used to quantify the amount of ligand adsorbed per bionanoparticle. As ligands can change conformations upon adsorption, using ES-DMA for such applications may be flawed. This issue has been identified and a solution has been provided by integrating a mass analyzer after the ES-DMA. After correcting for these artifacts, this dissertation delves into characterization of different types of bionanoparticles and demonstrates that ES-DMA has several advantages over other traditional techniques such as transmission electron microscopy, size exclusion chromatography, analytical ultracentrifugation, dynamic light scattering and plaque assay and thus has immense potential to become a process analytical technique in biomanufacturing environments

Evaluation of electrospray differential mobility analysis for virus particle analysis: Potential applications for biomanufacturing.

The technique of electrospray differential mobility analysis (ES-DMA) was examined as a potential potency assay for routine virus particle analysis in biomanufacturing environments (e.g., evaluation of vaccines and gene delivery products for lot release) in the context of the International Committee of Harmonisation (ICH) Q2 guidelines. ES-DMA is a rapid particle sizing method capable of characterizing certain aspects of the structure (such as capsid proteins) and obtaining complete size distributions of viruses and virus-like particles. It was shown that ES-DMA can distinguish intact virus particles from degraded particles and measure the concentration of virus particles when calibrated with nanoparticles of known concentration. The technique has a measurement uncertainty of ≈20%, is linear over nearly 3 orders of magnitude, and has a lower limit of detection of ≈10(9)particles/mL. This quantitative assay was demonstrated for non-enveloped viruses. It is expected that ES-DMA will be a useful method for applications involving production and quality control of vaccines and gene therapy vectors for human use

STL Files for Table S1 (Supporting Information)

This folder contains STL files that are necessary to print the adult headform for OSEL's regulatory science Tool titled "Modified NIOSH’s Adult Manikin Fit (MAMF) Test Method for Assessing Reuse of FDA Cleared N95 Respirators"</p

Enhancement of ICRP's Lung Deposition Model for Pathogenic Bioaerosols

<p>Terrorist attacks using pathogenic bioaerosols pose a significant public-health threat. Modeling the risk associated with such attacks is valuable from the standpoint of disaster preparedness. To attain greater flexibility in bioterrorism risk modeling, we have developed an open-source lung deposition code based on the International Committee for Radiological Protection (ICRP) Publication 66 (ICRP 1994). This article describes modifications to ICRP's lung deposition model to fit the bioaerosol context and discusses the impact of exposure from a few monodisperse pathogenic toxins such as botulinum toxin, influenza virus, and <i>Bacillus anthracis</i> to infants and adults. As most existing commercial lung deposition codes are not open-source, this code provides users a platform template that can be modified to meet their needs.</p

Quantification of leakage of sub-micron aerosols through surgical masks and facemasks for pediatric use

<p>Surgical respirators, surgical masks (SMs), and facemasks for pediatric use (FPUs) are routinely used in the U.S. healthcare industry as personal protective equipment (PPE) against infectious diseases. While N95s including surgical respirators have been routinely studied, SMs and FPUs have not received as much attention, particularly in the context of aerosolized threats. This is because SMs and PFUs are not designed to protect against sub-micron aerosols. However, with the possibility of new or re-emerging airborne diseases or bio-aerosol weapons lingering, combined with the limited availability of respirators and logistical issues associated with fit-testing millions, the general adult and pediatric populations may elect to wear SMs and FPUs, respectively, in the case of a pandemic or a bio-terrorist attack. When a person dons a PPE, gaps are created between the wearer's face and the PPE, and aerosols leaking through these gaps can be an important contributor to the risk of infection compared to filtered aerosols. To understand and quantify the contribution of leakage of aerosols through gaps, with particular emphasis on SMs and FPUs, this study investigated leakage of charge-neutralized, polydispersed, dried sodium-chloride aerosols across different brands of PPE. Different breathing rates, aerosol particle sizes, and gap sizes were considered. A few major findings of this study were: (a) leakage, is not a strong function of sub-micron aerosol size; (b) for the same gap size, leakage of aerosols through surgical respirators can often be higher than in SMs and FPUs; and (c) as the gap size increases, the increase in leakage through surgical respirators is higher compared for SMs and FPUs, implying that some SMs and FPUs that possess electret layers may be preferable to N95s that have not been fit-tested. The results obtained can also be used to explain conflicting findings from clinical studies on the effectiveness of SMs when compared to N95s and can be input into risk-assessment models to determine the increase in infection rate resulting from deployment of PPE under less-than-ideal conditions.</p

Evaluation of electrospray differential mobility analysis for virus particle analysis: Potential applications for biomanufacturing.

The technique of electrospray differential mobility analysis (ES-DMA) was examined as a potential potency assay for routine virus particle analysis in biomanufacturing environments (e.g., evaluation of vaccines and gene delivery products for lot release) in the context of the International Committee of Harmonisation (ICH) Q2 guidelines. ES-DMA is a rapid particle sizing method capable of characterizing certain aspects of the structure (such as capsid proteins) and obtaining complete size distributions of viruses and virus-like particles. It was shown that ES-DMA can distinguish intact virus particles from degraded particles and measure the concentration of virus particles when calibrated with nanoparticles of known concentration. The technique has a measurement uncertainty of ≈20%, is linear over nearly 3 orders of magnitude, and has a lower limit of detection of ≈10(9)particles/mL. This quantitative assay was demonstrated for non-enveloped viruses. It is expected that ES-DMA will be a useful method for applications involving production and quality control of vaccines and gene therapy vectors for human use

Quantifying Ligand Adsorption to Nanoparticles Using Tandem Differential Mobility Mass Analysis

Although electrospray-differential mobility analyzers (ES-DMA) have been previously employed to characterize ligand binding to nanoparticles, absolute quantification of surface coverage can be inaccurate at times because of ligand conformational effects. In this Letter, we report a quantitative technique by in-flight coupling of a particle mass analyzer (APM) with ES-DMA, thus enabling a direct quantitative analysis of mass independent of particle size, material, morphology and conformation. We demonstrate the utility of ES-DMA–APM by studying two model complex systems (gold nanoparticle–bovine serum albumin and polystyrene bead–antibody) as a function of concentration and pH. Our results obtained with ES-DMA–APM are in excellent agreement with prior work. We anticipate that this will enhance the capabilities of online quantitative characterization of ligand binding to nanoparticles

Technical considerations for medical device manufacturers when designing gastrostomy tubes (G-tubes) using the new ISO 80369-3 connector.

BackgroundGastrostomy tubes (G-tubes) are typically used when people cannot eat food by mouth. The connector section that allows G-tubes to connect to other devices, such as feeding sets or syringes, has been modified on some of the devices to reduce misconnections in hospital settings. The narrow internal diameter of the new connector, standardized under ISO 80369-3, has caused some users to express concern about a reduced flow rate. Previous studies performed on commercial devices determined that it was not conclusive how much the ISO 80369-3 connector contributed towards the reduced flow rate, because when manufacturers designed these new connector-based devices, they often changed other geometric variables (such as distal tube diameter, or length) at the same time. Thus, it became difficult isolating the effect of the connector from other geometric variables.MethodThe key objective of this study was to investigate how different design variables impacted the flow rate through the G-tubes. 3D-printed devices were used to assess the geometric parameters in a systematic manner. Commercial diets and Newtonian analog fluids with matched viscosities were used for testing.ResultsThe flow path length of the "transition section" encompassing the standardized ISO 80369-3 connector in the new devices was found to cause reduced flow. Additionally, results showed that a shortened (≤ 10 mm) transition section, along with a 10% increase in the distal inner diameter of large bore devices (e.g., 24 Fr), can restore flow rates to levels consistent with the previous devices prior to the connector standardization.ConclusionsThe strategy for restoring flow rates to previous levels may help alleviate concerns raised by multiple stakeholders such as health care professionals, patients, caregivers and device manufacturers. In addition, the approach proposed here can be used as a tool for designing future G-tube devices