List acknowledgements and funding sources.
	 NIH-ES015022 and ES018274 (TRN)
	 NSF-Cooperative Agreement 1003907 (VCM)

The whole-body nanoparticle inhalation exposure step-by-step operating procedures are described as follows.
Note: 1) steps 1 and 3 should be performed in a fume hood; 2) operators must wear appropriate personal protective equipment (respirators, goggles and rubber gloves).
1. Conditioning TiO2 Nanoparticle Dry Powders
<ol>
	<li>Place nano-TiO2 powders in a nontransparent container.</li>
	<li>Leave the container lid open.</li>
	<li>Place the container in a dry desiccator for at least 24 hr for conditioning.</li>
</ol>
2. Warming up Data Acquisition and Control System, SMPS and ELPI and All Transducers
<ol>
	<li>Turn on the air monitoring and data acquisition system and power switches for aerosol monitoring SMPS (TSI Inc., Shoreview, MN) and ELPI (Dekati, Tampere, Finland), and warm the systems up for at least 1 hr.</li>
	<li>Turn on the power switches in all transducers to warm them up for at least 1 hr.</li>
</ol>
3. Loading TiO2 Nanoparticle Dry Powders into Aerosol Generators
<ol>
	<li>Open the cylinder caps on the aerosol generators, and replace the filters in the aerosol generators. Note: One aerosol generator has one cylinder. The number of aerosol generators to be used depends on the desired mass concentration of the particles in exposure chamber.</li>
	<li>Weigh ~4 g nano-TiO2 powders and load them in each cylinder.</li>
	<li>Replace the cylinder caps.</li>
	<li>All areas suspect of TiO2 contamination should be wet wiped.</li>
</ol>
4. Connecting Aerosol Generators to Inhalation Exposure Chamber
<ol>
	<li>Connect all the outlets of the aerosol generators via a manifold to a cyclone separator which is at the inlet of the inhalation exposure chamber (TSE Systems GmbH, Bad Homburg, Germany).</li>
	<li>Connect compressed air tubing to the Venturi dispersers in the aerosol generators.</li>
</ol>
5. Connecting Air Monitoring and Aerosol Sampling Inlets to the Inhalation Exposure Chamber
<ol>
	<li>Connect temperature &amp; relative humidity (RH), pressure, O2 &amp; CO2 sensors supplied by TSE Systems to test atmosphere monitoring ports on the inhalation exposure chamber.</li>
	<li>Connect the inlet of an aerosol dilutor to one of the aerosol sampling ports on the inhalation exposure chamber, and then connect its outlet to the inlet of the ELPI.</li>
	<li>Connect SMPS to one of the aerosol sampling ports on the inhalation exposure chamber.</li>
	<li>Connect inlet of a particle concentration monitor (TSE Systems) to one of the aerosol sampling ports on the exposure chamber.</li>
	<li>Weigh PTFE membrane filter (P/N 66149, Pall corporation, Ann Arbor, Michigan) and load filter into a stainless steel filter holder (In-Tox products, Moriarty NM).</li>
	<li>Connect the inlet of the stainless steel filter holder with a pre-weighed filter to one of the aerosol sampling ports on the inhalation exposure chamber, and connect its outlet to a sampling pump.</li>
</ol>
6. Activate Data Acquisition Systems
<ol>
	<li>Activate ELPI data acquisition software, ELPIVI, check setup parameters, and turn on the flush pump for ~5 min and then zero the ELPI. Record pre-exposure concentration.</li>
	<li>Activate SMPS data acquisition software. Record pre-exposure concentration.</li>
	<li>Activate software, Daco (TSE Systems), for monitoring and controlling air flow rate, temperature and RH chamber pressure, temperature &amp; RH, O2 and CO2.</li>
</ol>
7. Loading Experimental Animals into the Inhalation Exposure Chamber
<ol>
	<li>Weigh the experimental animals.</li>
	<li>Mark the experimental animals and cages so that the animals can be put back in the same cages after the exposure if needed.</li>
	<li>Open the door of the inhalation exposure chamber, and load experimental animals into the wired cages.</li>
	<li>Water may be provided for animals.</li>
	<li>Close and secure the door of the inhalation exposure chamber.</li>
	<li>Frequently observe animals through the exposure chamber observation windows for signs of distress. Animals should be relaxed and behaving normally. Stop the exposure if rapid/labored breathing, abnormal appearance, postural abnormalities or immobility are observed. Remove the animals, return them to their original cages, contact attending veterinarian and/or initiate appropriate Institutional Animal Care and Use Committee procedures.</li>
</ol>
Note: Operators must wear personal protective equipment when performing steps 8.7, 8.8 and 8.17.
8. Exposing Small Animals to Nanoparticle Aerosols
<ol>
	<li>Turn on the exhaust vacuum pump of the inhalation exposure chamber.</li>
	<li>Run data acquisition software, Daco, to: a) supply filtered dry air to the exposure chamber, b) control the pressure in the exposure chamber, and c) collect the data of the exposure environment, such as pressure, temperature, RH, O2 and CO2.</li>
	<li>Establish a slightly negative pressure (set point = -0.2 mbar) in the chamber pressure.</li>
	<li>Turn on the aerosol generators.</li>
	<li>Run ELPI and SMPS data acquisition software to continuously monitor particle size and relative mass concentration in the inhalation exposure chamber.</li>
	<li>When the aerosol concentration is stable, i.e. the concentration profile on ELPI monitor reached plateau (Normally: this takes 20 min after the aerosol generators are in operation), set up the sampling time (for example, 1 hr) and turn on the aerosol sampling pump to collect representative sample of nanoparticles with filters.</li>
	<li>Once the sampling time is reached, remove the filters and plug the sampling ports with rubber plugs to prevent test materials from escaping the exposure chamber.</li>
	<li>Weigh the filters, and calculate the mean mass concentration in the exposure chamber as described above.</li>
	<li>If the mean concentration is off the targeted concentration, manually adjust the airflow in the generators to ensure the targeted concentration is attained.</li>
	<li>Calculate particle deposition in the animal lungs as D = C x Vm x t x Fr, where D = Dose, C = mean mass concentration of test material, Vm= minute volume, t = exposure duration, and Fr = fraction of material that is deposited or absorbed.</li>
	<li>Replace the filters in the filter holders with clean, pre-weighted filters, and repeat steps 8.6 and 8.8.</li>
	<li>Based upon the real mass concentration in the exposure chamber and targeted particle deposition in the animal lungs, estimate the remaining exposure time as, tremain = (Dtargeted -D) / (C x Vm x Fr), where tremain = remain exposure duration, Dtargeted = targeted dose, C = mean mass concentration of test material, Vm = minute volume, Fr = fraction of material that is deposited or absorbed.</li>
	<li>Turn off the aerosol generator when tremain is reached.</li>
	<li>Before removing the animals from the exposure chamber, flush the inhalation exposure chamber with the filtered air until the particle concentration indicated in the monitor is close to the pre-exposure particle concentration in the chamber.</li>
	<li>Turn off the chamber exhaust vacuum pump.</li>
	<li>Stop data acquisition software, Daco.</li>
	<li>After exposure, observe animals to verify normal respiration and behavior, and document that no other study complications exist. If nasal discharge, respiratory distress or any other animal welfare complications are observed, contact attending veterinarian and/or initiate appropriate Institutional Animal Care and Use Committee procedures.</li>
	<li>Stop ELPI and SMPS data acquisition software.</li>
</ol>
9. Creating Test Report
9.1 Test conditions include
<ol>
	<li>Description of the aerosol generation system and its operating parameters used in this test.</li>
	<li>Description of the exposure apparatus including design, type, dimensions and its operating parameters used during the exposure.</li>
	<li>Equipment for measuring temperature, humidity, particle size, and actual concentration.</li>
	<li>Treatment of exhaust air and the method of housing the animals in the test chamber when used.</li>
</ol>
9.2 Exposure atmosphere data include
<ol>
	<li>Airflow rates through the inhalation equipment.</li>
	<li>Temperature and humidity of the air.</li>
	<li>Actual (analytical or gravimetric) concentration in the aerosol sampling zone which is near the animal cages.</li>
	<li>Particle size distribution, and calculated count median aerodynamic diameter and geometric standard deviation.</li>
	<li>Explanation as to why the desired chamber concentration and/or particle size could not be achieved (if applicable), and the efforts taken to comply with these aspects of the guidelines.</li>
</ol>
9.3 Other
<ol>
	<li>Slightly negative pressure in the room containing inhalation facility should be maintained to prevent test materials from escaping inhalation exposure lab.</li>
	<li>Clean the exposure chamber daily to eliminate the influences of the animal wastes.</li>
	<li>ELPI, SMPS and other instruments should be cleaned and calibrated based on the user manuals.</li>
</ol>

<ol>
	<li>Bide, R. W., Armour, S. J., Yee, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Allometric+respiration/body+mass+data+for+animals+to+be+used+for+estimates+of+inhalation+toxicity+to+young+adult+humans.">Allometric respiration/body mass data for animals to be used for estimates of inhalation toxicity to young adult humans.</a> J. Appl. Toxicol. 20 (4), 273-290 (2000).</li><li>Guyton, A. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+respiratory+patterns+in+laboratory+animals.">Analysis of respiratory patterns in laboratory animals.</a> Am. J. Physiol. 150, 70-77 (1947).</li><li>Knuckles, T. L., Yi, J., Frazer, D. G., Leonard, H. D., Chen, B. T., Castranova, V., Nurkiewicz, T. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanoparticle+inhalation+alters+systemic+arteriolar+vasoreactivity+through+sympathetic+and+cyclooxygenase-mediated+pathways.">Nanoparticle inhalation alters systemic arteriolar vasoreactivity through sympathetic and cyclooxygenase-mediated pathways.</a> Nanotoxicology. , 1-12 (2011).</li><li>Pauluhn, J., Mohr, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Repeated+4-week+inhalation+exposure+of+rats:+effect+of+low-,+intermediate,+and+high-humidity+chamber+atmosphere.">Repeated 4-week inhalation exposure of rats: effect of low-, intermediate, and high-humidity chamber atmosphere.</a> Exp. Toxic Pathol. , 178-187 (1999).</li><li>Schmoll, L. H., Elzey, S., Grassian, V. H., O'Shaughnessy, P. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanoparticle+aerosol+generation+methods+from+bulk+powders+for+inhalation+exposure+studies.">Nanoparticle aerosol generation methods from bulk powders for inhalation exposure studies.</a> Nanotoxicology. 3, 265-275 (2009).</li><li>To, D., Yin, X., Sundaresan, S., Dave, R. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deagglomeration+of+nano-particle+aggregates+via+rapid+expansion+of+high+pressure+suspensions.">Deagglomeration of nano-particle aggregates via rapid expansion of high pressure suspensions.</a> AIChE J. 55 (11), 2756-3032 (2009).</li><li>U.S. Environmental Protection Agency (US EPA). <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Health+effects+test+guidelines:+OPPTS.,+870.1300.+Acute+inhalation+toxicity.">Health effects test guidelines: OPPTS., 870.1300. Acute inhalation toxicity.</a> EPA. , 712-C-98-193 (1998).</li><li>Wong, B. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Automated+feedback+control+of+an+inhalation+exposure+system+with+discrete+sampling+intervals:+testing,+performance,+and+modeling.">Automated feedback control of an inhalation exposure system with discrete sampling intervals: testing, performance, and modeling.</a> Inhal. Toxicol. 15, 729-743 (2003).</li><li>Wong, B. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inhalation+Exposure+Systems:+Design,+Methods+and+Operation.">Inhalation Exposure Systems: Design, Methods and Operation.</a> Toxicologic Pathology. 35, 3-14 (2007).</li><li>Yi, J., Nurkiewicz, T. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanoparticle+Aerosol+Generator.">Nanoparticle Aerosol Generator.</a> US patent. , (2011).</li></ol>

The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health. The mention of any company names or products does not imply an endorsement by NIOSH, nor does it imply that alternative products are unavailable, or unable to be substituted after appropriate evaluation.

We have assembled and described here in a whole-body nanoparticle aerosol inhalation exposure system. The system functionality was validated with state-of-the-art nanoparticle aerosol characterization techniques. With a novel nanoparticle aerosol generation system, this inhalation exposure system can provide a well characterized, controlled and uniform nanoparticle aerosol test atmosphere with relatively consistent temperature, humidity, air flow, and oxygen content for experimental animals. The exposure system is most e...

<table border="1">
		<tbody>
		 <tr>
			<td>Name of Reagent/Material</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		 </tr>
		 <tr>
			<td>Inhalation exposure system</td>
			<td>TSE Systems GmbH, Bad Homburg, Germany</td>
			<td></td>
			<td></td>
		 </tr>
		 <tr>
			<td>Air monitoring system</td>
			<td>TSE Systems GmbH, Bad Homburg, Germany</td>
			<td></td>
			<td></td>
		 </tr>
		 <tr>
			<td>Titanium dioxide Aeroxide P25</td>
			<td>Evonik, Germany</td>
			<td></td>
			<td></td>
		 </tr>
		 <tr>
			<td>Scanning mobility particle sizer-3936L75</td>
			<td>TSI Inc., Shoreview, MN</td>
			<td></td>
			<td></td>
		 </tr>
		 <tr>
			<td>Electric low pressure impactor, Standard 10 LPM</td>
			<td>Dekati, Tampere, Finland</td>
			<td></td>
			<td></td>
		 </tr>
		 <tr>
			<td>Ultra Micro Balance, XP2U</td>
			<td>METTLER TOLEDO, Switzerland</td>
			<td></td>
			<td></td>
		 </tr>
		 <tr>
			<td>Field Emission Scanning Electron Microscope-S-4800</td>
			<td>Hitachi, Japan</td>
			<td></td>
			<td></td>
		 </tr>
		 <tr>
			<td>Energy dispersive X-ray analysis </td>
			<td>Princeton Gamma-Tech, Rocky Hill, N.J.</td>
			<td></td>
			<td></td>
		 </tr>
		 <tr>
			<td>Nuclepore polycarbonate filters </td>
			<td>Whatman, Clinton, PA</td>
			<td></td>
			<td></td>
		 </tr>
		 <tr>
			<td>PTFE membrane filters </td>
			<td>Pall corporation, Ann Arbor, Michigan </td>
			<td></td>
			<td></td>
		 </tr>
		</tbody>
 </table>

whole-body nanoparticle aerosol inhalation exposures

Inhalation is the most likely exposure route for individuals working with aerosolizable engineered nano-materials (ENM). To properly perform nanoparticle inhalation toxicology studies, the aerosols in a chamber housing the experimental animals must have: 1) a steady concentration maintained at a desired level for the entire exposure period; 2) a homogenous composition free of contaminants; and 3) a stable size distribution with a geometric mean diameter &lt; 200 nm and a geometric standard deviation &sigma;g &lt; 2.5 5. The generation of aerosols containing nanoparticles is quite challenging because nanoparticles easily agglomerate. This is largely due to very strong inter-particle forces and the formation of large fractal structures in tens or hundreds of microns in size 6, which are difficult to be broken up. Several common aerosol generators, including nebulizers, fluidized beds, Venturi aspirators and the Wright dust feed, were tested; however, none were able to produce nanoparticle aerosols which satisfy all criteria 5.
A whole-body nanoparticle aerosol inhalation exposure system was fabricated, validated and utilized for nano-TiO2 inhalation toxicology studies. Critical components: 1) novel nano-TiO2 aerosol generator; 2) 0.5 m3 whole-body inhalation exposure chamber; and 3) monitor and control system. Nano-TiO2 aerosols generated from bulk dry nano-TiO2 powders (primary diameter of 21 nm, bulk density of 3.8 g/cm3) were delivered into the exposure chamber at a flow rate of 90 LPM (10.8 air changes/hr). Particle size distribution and mass concentration profiles were measured continuously with a scanning mobility particle sizer (SMPS), and an electric low pressure impactor (ELPI). The aerosol mass concentration (C) was verified gravimetrically (mg/m3). The mass (M) of the collected particles was determined as M = (Mpost-Mpre), where Mpre and Mpost are masses of the filter before and after sampling (mg). The mass concentration was calculated as C = M/(Q*t), where Q is sampling flowrate (m3/min), and t is the sampling time (minute). The chamber pressure, temperature, relative humidity (RH), O2 and CO2 concentrations were monitored and controlled continuously. Nano-TiO2 aerosols collected on Nuclepore filters were analyzed with a scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analysis.
In summary, we report that the nano-particle aerosols generated and delivered to our exposure chamber have: 1) steady mass concentration; 2) homogenous composition free of contaminants; 3) stable particle size distributions with a count-median aerodynamic diameter of 157 nm during aerosol generation. This system reliably and repeatedly creates test atmospheres that simulate occupational, environmental or domestic ENM aerosol exposures.

An inhalation exposure study typically involves maintaining an experimental animal in a known and constant test environment while exposing the experimental animal to a defined concentration of a test material 8,9. The whole-body nanoparticle inhalation exposure system is shown in Figure 1. The whole-body chamber was operated on a dynamic flow basis where there was a 90 LPM continuous flow of air through the chamber. This air flow provided 10.8 air changes/hr which exceeds the minimum number of...

Watch this Scientific Journal Video about Whole-Body Nanoparticle Aerosol Inhalation Exposures at JoVE.com

Whole-Body Nanoparticle Aerosol Inhalation Exposures

A whole-body nanoparticle aerosol inhalation exposure facility was constructed for nano-sized titanium dioxide (TiO2) inhalation toxicology studies. This system provides nano-TiO2 aerosol test atmospheres that have: 1) a steady mass concentration; 2) a homogenous composition free of contaminants; and 3) a stable particle size distribution during aerosol generation.

Inhalation is the most likely exposure route for individuals working with aerosolizable engineered nano-materials (ENM). To properly perform nanoparticle ...

whole-body-nanoparticle-aerosol-inhalation-exposures

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Biology

15.7K vistas.  West Virginia University. Una instalación de la exposición por inhalación de aerosoles de nanopartículas de todo el cuerpo se construye para el dióxido de titanio de tamaño nanométrico (TiO 2) Estudios de toxicología de inhalación. Este sistema proporciona nano-TiO 2 Atmósferas de prueba de aerosol que tienen: 1) una concentración constante de masa; 2) una composición homogénea libre de contaminantes, y 3) una distribución de tamaño de partícula es...

Video: Whole-Body Nanoparticle Aerosol Inhalation Exposures

Measuring Respiratory Function in Mice Using Unrestrained Whole-body Plethysmography

Respiratory dysfunction is one of the leading causes of morbidity and mortality in the world and the rates of mortality continue to rise. Quantitative assessment of lung function in rodent models is an important tool in the development of future therapies. Commonly used techniques for assessing respiratory function including invasive plethysmography and forced oscillation. While these techniques provide valuable information, data collection can be fraught with artefacts and experimental variability due to the need for anesthesia and/or invasive instrumentation of the animal. In contrast, unrestrained whole-body plethysmography (UWBP) offers a precise, non-invasive, quantitative way by which to analyze respiratory parameters. This technique avoids the use of anesthesia and restraints, which is common to traditional plethysmography techniques. This video will demonstrate the UWBP procedure including the equipment set up, calibration and lung function recording. It will explain how to analyze the collected data, as well as identify experimental outliers and artefacts that results from animal movement. The respiratory parameters obtained using this technique include tidal volume, minute volume, inspiratory duty cycle, inspiratory flow rate and the ratio of inspiration time to expiration time. UWBP does not rely on specialized skills and is inexpensive to perform. A key feature of UWBP, and most appealing to potential users, is the ability to perform repeated measures of lung function on the same animal.

The assessment of respiratory physiology has traditionally relied upon techniques, which require restraint or sedation of the animal. Unrestrained whole-body plethysmography, however, provides precise, non-invasive, quantitative analysis of respiratory physiology in animal models. In addition, the technique allows repeated respiratory assessment of mice allowing for longitudinal studies.

Respiratory dysfunction is one of the leading causes of morbidity and mortality in the world and the rates of mortality continue to rise. Quantitative ...

Chitosan/Interfering RNA Nanoparticle Mediated Gene Silencing in Disease Vector Mosquito Larvae

Vector mosquitoes inflict more human suffering than any other organism&#8212;and kill more than one million people each year. The mosquito genome projects facilitated research in new facets of mosquito biology, including functional genetic studies in the primary African malaria vector Anopheles gambiae and the dengue and yellow fever vector Aedes aegypti. RNA interference- (RNAi-) mediated gene silencing has been used to target genes of interest in both of these disease vector mosquito species. Here, we describe a procedure for preparation of chitosan/interfering RNA nanoparticles that are combined with food and ingested by larvae. This technically straightforward, high-throughput, and relatively inexpensive methodology, which is compatible with long double stranded RNA (dsRNA) or small interfering RNA (siRNA) molecules, has been used for the successful knockdown of a number of different genes in A. gambiae and A. aegypti larvae. Following larval feedings, knockdown, which is verified through qRT-PCR or in situ hybridization, can persist at least through the late pupal stage. This methodology may be applicable to a wide variety of mosquito and other insect species, including agricultural pests, as well as other non-model organisms. In addition to its utility in the research laboratory, in the future, chitosan, an inexpensive, non-toxic and biodegradable polymer, could potentially be utilized in the field.

Here we describe a procedure for inhibiting gene function in disease vector mosquitoes through the use of chitosan/interfering RNA nanoparticles that are ingested by larvae.

Vector mosquitoes inflict more human suffering than any other organism&#8212;and kill more than one million people each year. The mosquito genome projects ...

A Method for Selecting Structure-switching Aptamers Applied to a Colorimetric Gold Nanoparticle Assay

Small molecules provide rich targets for biosensing applications due to their physiological implications as biomarkers of various aspects of human health and performance. Nucleic acid aptamers have been increasingly applied as recognition elements on biosensor platforms, but selecting aptamers toward small molecule targets requires special design considerations. This work describes modification and critical steps of a method designed to select structure-switching aptamers to small molecule targets. Binding sequences from a DNA library hybridized to complementary DNA capture probes on magnetic beads are separated from nonbinders via a target-induced change in conformation. This method is advantageous because sequences binding the support matrix (beads) will not be further amplified, and it does not require immobilization of the target molecule. However, the melting temperature of the capture probe and library is kept at or slightly above RT, such that sequences that dehybridize based on thermodynamics will also be present in the supernatant solution. This effectively limits the partitioning efficiency (ability to separate target binding sequences from nonbinders), and therefore many selection rounds will be required to remove background sequences. The reported method differs from previous structure-switching aptamer selections due to implementation of negative selection steps, simplified enrichment monitoring, and extension of the length of the capture probe following selection enrichment to provide enhanced stringency. The selected structure-switching aptamers are advantageous in a gold nanoparticle assay platform that reports the presence of a target molecule by the conformational change of the aptamer. The gold nanoparticle assay was applied because it provides a simple, rapid colorimetric readout that is beneficial in a clinical or deployed environment. Design and optimization considerations are presented for the assay as proof-of-principle work in buffer to provide a foundation for further extension of the work toward small molecule biosensing in physiological fluids.

A protocol is provided to select structure-switching aptamers for small molecule targets based on a tunable stringency magnetic bead selection method. Aptamers selected with structure-switching properties are beneficial for assays that require a conformational change to signal the presence of a target, such as the described gold nanoparticle assay.

Small molecules provide rich targets for biosensing applications due to their physiological implications as biomarkers of various aspects of human health ...

Design and Development of Aptamer&#8211;Gold Nanoparticle Based Colorimetric Assays for In-the-field Applications

The design and development of an aptamer&#8211;gold nanoparticle (AuNP) colorimetric assay for the detection of small molecules for in-the-field applications was examined. Target selective AuNP based color assays have been developed in controlled proof-of-concept laboratory settings. However, these schemes have not been exerted to a point of failure to determine their practical use beyond laboratory settings. This work describes a generic approach to design, develop, and troubleshoot an aptamer-AuNP colorimetric assay for small molecule analytes and using the assay for in-the-field settings. The assay is advantageous because adsorbed aptamers passivate the nanoparticle surfaces and provide a means to reduce and eliminate false positive responses to non-target analytes. Transitioning this system to practical uses required defining not only the shelf-life of the aptamer-AuNP assay, but establishing methods and procedures for extending the long-term storage capabilities. Also, one of the recognized concerns with colorimetric readout is the burden placed on analysts to accurately identify often subtle changes in color. To lessen the responsibility on analysts in the field, a color analysis protocol was designed to perform the color identification duties without the need for performing this task on laboratory grade equipment. The method for creating and testing the data analysis protocol is described. However to understand and influence the design of adsorbed aptamer assays, the interactions associated with the aptamer, target, and AuNPs require further study. The knowledge gained could lead to tailoring aptamers for improved functionality.

The design and development of an aptamer&#8211;gold nanoparticle colorimetric assay for the detection of small molecules for in-the-field applications was examined. Additionally, a smart-device colorimetric application (app) was validated and long-term storage of the assay was established for use in the field.

The design and development of an aptamer&#8211;gold nanoparticle (AuNP) colorimetric assay for the detection of small molecules for in-the-field ...

An Air-liquid Interface Bronchial Epithelial Model for Realistic, Repeated Inhalation Exposure to Airborne Particles for Toxicity Testing

For toxicity testing of airborne particles, air-liquid interface (ALI) exposure systems have been developed for in vitro tests in order to mimic realistic exposure conditions. This puts specific demands on the cell culture models. Many cell types are negatively affected by exposure to air (e.g., drying out) and only remain viable for a few days. This limits the exposure conditions that can be used in these models: usually relatively high concentrations are applied as a cloud (i.e., droplets containing particles, which settle down rapidly) within a short period of time. Such experimental conditions do not reflect realistic long-term exposure to low concentrations of particles. To overcome these limitations the use of a human bronchial epithelial cell line, Calu-3 was investigated. These cells can be cultured at ALI conditions for several weeks while retaining a healthy morphology and a stable monolayer with tight junctions. In addition, this bronchial model is suitable for testing the effects of repeated exposures to low, realistic concentrations of airborne particles using an ALI exposure system. This system uses a continuous airflow in contrast to other ALI exposure systems that use a single nebulization producing a cloud. Therefore, the continuous flow system is suitable for repeated and prolonged exposure to airborne particles while continuously monitoring the particle characteristics, exposure concentration, and delivered dose. Taken together, this bronchial model, in combination with the continuous flow exposure system, is able to mimic realistic, repeated inhalation exposure conditions that can be used for toxicity testing.

Described is the cell culture and exposure method of an in vitro bronchial model for realistic, repeated inhalation exposure to particles for toxicity testing.

For toxicity testing of airborne particles, air-liquid interface (ALI) exposure systems have been developed for in vitro tests in order to mimic realistic ...

Dosimetry for Cell Irradiation using Orthovoltage (40-300 kV) X-Ray Facilities

The importance of dosimetry protocols and standards for radiobiological studies is self-evident. Several protocols have been proposed for dose determination using low energy X-ray facilities, but depending on the irradiation configurations, samples, materials or beam quality, it is sometimes difficult to know which protocol is the most appropriate to employ. We, therefore, propose a dosimetry protocol for cell irradiations using low energy X-ray facility. The aim of this method is to perform the dose estimation at the level of the cell monolayer to make it as close as possible to real cell irradiation conditions. The different steps of the protocol are as follows: determination of the irradiation parameters (high voltage, intensity, cell container etc.), determination of the beam quality index (high voltage-half value layer couple), dose rate measurement with ionization chamber calibrated in air kerma conditions, quantification of the attenuation and scattering of the cell culture medium with EBT3 radiochromic films, and determination of the dose rate at the cellular level. This methodology must be performed for each new cell irradiation configuration as the modification of only one parameter can strongly impact the real dose deposition at the level of the cell monolayer, particularly involving low energy X-rays.

Dosimetry for Cell Irradiation using Orthovoltage 40-300 kV X-Ray Facilities

This document describes a new dosimetry protocol for cell irradiations using low energy X-ray equipment. Measurements are performed in conditions simulating real cell irradiation conditions as much as possible.

The importance of dosimetry protocols and standards for radiobiological studies is self-evident. Several protocols have been proposed for dose ...

Construction of a Realistic, Whole-Body, Three-Dimensional Equine Skeletal Model using Computed Tomography Data

Therapies based upon whole-body biomechanical assessments are successful for injury prevention and rehabilitation in human athletes. Similar approaches have rarely been used to study equine athletic injury. Degenerative osteoarthritis caused by mechanical stress can originate from chronic postural dysfunction, which, because the primary dysfunction is often distant from the site of tissue injury, is best identified through modeling whole-body biomechanics. To characterize whole-body equine kinematics, a realistic skeletal model of a horse was created from equine computed tomography (CT) data that can be used for functional anatomical and biomechanical modeling. Equine CT data were reconstructed into individual three-dimensional (3D) data sets (i.e., bones) using 3D visualization software and assembled into a complete 3D skeletal model. The model was then rigged and animated using 3D animation and modeling software. The resulting 3D skeletal model can be used to characterize equine postures associated with degenerative tissue changes as well as to identify postures that reduce mechanical stress at the sites of tissue injury. In addition, when animated into 4D, the model can be used to demonstrate unhealthy and healthy skeletal movements and can be used to develop preventative and rehabilitative individualized therapies for horses with degenerative lamenesses. Although the model will soon be available for download, it is currently in a format that requires access to the 3D animation and modeling software, which has quite a learning curve for new users. This protocol will guide users in (1) developing such a model for any organism of interest and (2) using this specific equine model for their own research questions.

The purpose of this protocol is to describe the method of creation of a realistic, whole-body, skeletal model of a horse that can be used for functional anatomical and biomechanical modeling to characterize whole-body mechanics.

Therapies based upon whole-body biomechanical assessments are successful for injury prevention and rehabilitation in human athletes. Similar approaches ...

Nanoparticle Tracking Analysis for the Quantification and Size Determination of Extracellular Vesicles

The physiological and pathophysiological roles of extracellular vesicles (EVs) have become increasingly recognized, making the EV field a quickly evolving area of research. There are many different methods for EV isolation, each with distinct advantages and disadvantages that affect the downstream yield and purity of EVs. Thus, characterizing the EV prep isolated from a given source by a chosen method is important for interpretation of downstream results and comparison of results across laboratories. Various methods exist for determining the size and quantity of EVs, which can be altered by disease states or in response to external conditions. Nanoparticle tracking analysis (NTA) is one of the prominent technologies used for high-throughput analysis of individual EVs. Here, we present a detailed protocol for quantification and size determination of EVs isolated from mouse perigonadal adipose tissue and human plasma using a breakthrough technology for NTA representing major advances in the field. The results demonstrate that this method can deliver reproducible and valid total particle concentration and size distribution data for EVs isolated from different sources using different methods, as confirmed by transmission electron microscopy. The adaptation of this instrument for NTA will address the need for standardization in NTA methods to increase rigor and reproducibility in EV research.

We demonstrate how to use a novel nanoparticle tracking analysis instrument to estimate the size distribution and total particle concentration of extracellular vesicles isolated from mouse perigonadal adipose tissue and human plasma.

The physiological and pathophysiological roles of extracellular vesicles (EVs) have become increasingly recognized, making the EV field a quickly evolving ...

Antimicrobial Efficacy of Nano-Herbal-Coated Fabrics

An Antimicrobial Fabric Using Nano-Herbal Encapsulation of Essential Oils

Lab coats are widely used in biohazard laboratories and healthcare facilities as protective garments to prevent direct exposure to pathogens, spills, and burns. These cotton-based protective coats provide ideal conditions for microbial growth and attachment sites due to their porous nature, moisture-holding capacity, and retention of warmth from the user&#39;s body. Several studies have demonstrated the survival of pathogenic bacteria on hospital garments and lab coats, acting as vectors of microbial transmission.
A common approach to fix these problems is the application of antimicrobial agents in textile finishing, but concerns have been raised due to the toxicity and environmental effects of many synthetic chemicals. The ongoing pandemic has also opened a window for the investigation of effective antimicrobials and eco-friendly and toxic-free formulations. This study uses two natural bioactive compounds, carvacrol and thymol, encapsulated in chitosan nanoparticles, which guarantee effective protection against four human pathogens with up to a 4-log reduction (99.99%). These pathogens are frequently detected in lab coats used in biohazard laboratories.
The treated fabrics also resisted up to 10 wash cycles with 90% microbial reduction, which is sufficient for the intended use. We made modifications to the existing standard fabric tests to better represent the typical scenarios of lab coat usage. These refinements allow for a more accurate evaluation of the effectiveness of antimicrobial lab coats and for the simulation of the fate of any accidental microbial spills that must be neutralized within a short time. Further studies are recommended to investigate the accumulation of pathogens over time on antimicrobial lab coats compared to regular protective coats.

Author Spotlight: An Antimicrobial Fabric Using Nano-Herbal Encapsulation of Essential Oils  

Antimicrobial lab coats prevent the cross-contamination of pathogen accumulation and accidental bio-spills. Here, we describe the protocol for developing a skin-friendly antimicrobial fabric using nano-herbal encapsulation and modified standard tests to precisely evaluate the efficacy and suitability for typical usage of the lab coat.

Lab coats are widely used in biohazard laboratories and healthcare facilities as protective garments to prevent direct exposure to pathogens, spills, and ...

Direct Synthesis of Gold Nanoparticles for Protein Localization Analysis

Direct Synthesis of EM-Visible Gold Nanoparticles in Cells for Protein Localization Analysis with Well-Preserved Ultrastructure

Analyzing the precise localization of protein molecules in cells with ultrastructural resolution is of great significance for the study of various physiological or pathological processes in all living organisms. Therefore, the development of clonable tags that can be used as electron microscopy probes is of great value, just as fluorescent proteins have played a crucial role in the field of optical imaging. The autonucleation suppression mechanism (ANSM) was recently uncovered, which allows for the specific synthesis of gold nanoparticles (AuNPs) on cysteine-rich tags, such as metallothionein (MT) and antifreeze protein (AFP).
Based on the ANSM, an electron microscopy labeling technology was developed, which enables the specific detection of tagged proteins in prokaryotic and eukaryotic cells with an unprecedented labeling efficiency. This study illustrates a protocol for the detection of MTn (an engineered MT variant lacking aldehyde-reactive residues) fusion proteins in mammalian cells with well-preserved ultrastructure. In this protocol, high-pressure freezing and freeze-substitution fixation were performed using non-aldehyde fixatives (such as tannic acid, uranyl acetate) to preserve near-native ultrastructure and avoid damage to the tag activity caused by aldehyde crosslinking.
A simple one-step rehydration was used prior to the ANSM-based AuNP synthesis. The results showed that the tagged proteins targeted various organelles, including the membranes and the lumen of the endoplasmic reticulum (ER), and mitochondrial matrices were detected with high efficiency and specificity. This research provides biologists with a robust protocol to address an enormous range of biological questions at the single-molecule level in cellular ultrastructural contexts.

Author Spotlight: Direct Synthesis of EM-Visible Gold Nanoparticles in Cells for Protein Localization Analysis with Well-Preserved Ultrastructure  

The present protocol describes a clonable electron microscopy labeling technology for detecting metallothionein-tagged proteins in cells using a novel autonucleation suppression mechanism-based gold nanoparticle synthesis technique.