Name: low-cost, volume-controlled dipstick urinalysis for home-testing
Uploaded: 2021-05-08T13:00:00
Description: Watch this Scientific Journal Video about Low-Cost, Volume-Controlled Dipstick Urinalysis for Home-Testing at JoVE.com

This work was funded by the Dorothy J. Wingfield Phillips Chancellor Faculty Fellowship. Emily Kight was funded by NSF GRFP.

1. Fabricate and assemble the urinalysis device
<ol>
	<li>Fabricate the base plate (Figure 1A).
	<ol>
		<li>Use a computer-aided design (CAD) software to draw a rectangular area with dimensions 2.1641 in x 0.0547 in x 6.3828 in (W x H x L) using the polyline tool.</li>
		<li>Measure the test area (rectangular area encompassing the distance between the first and last pad and the width of the pads) on the dipstick. 
		NOTE: This information is needed to draw the through-holes that hold ...

<ol>
	<li>Lei, R., Huo, R., Mohan, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Expert+Review+of+Molecular+Diagnostics+Current+and+emerging+trends+in+point-of-care+urinalysis+tests.">Expert Review of Molecular Diagnostics Current and emerging trends in point-of-care urinalysis tests.</a> Expert Review of Molecular Diagnostics. 00, 1-16 (2020).</li><li>Kavuru, V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dipstick+analysis+of+urine+chemistry:+benefits+and+limitations+of+dry+chemistry-based+assays.">Dipstick analysis of urine chemistry: benefits and limitations of dry chemistry-based assays.</a> Postgraduate Medicine. 5481, (2019).</li><li>Pugia, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Technology+Behind+Diagnostic+Reagent+Strips.">Technology Behind Diagnostic Reagent Strips.</a> Laboratory Medicine. 31, 92-96 (2000).</li><li>Dungchai, W., Chailapakul, O., Henry, C. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrochemical+detection+for+paper-based+microfluidics.">Electrochemical detection for paper-based microfluidics.</a> Analytical Chemistry. 81, 5821-5826 (2009).</li><li>Van Delft, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prospective,+observational+study+comparing+automated+and+visual+point-of-care+urinalysis+in+general+practice.">Prospective, observational study comparing automated and visual point-of-care urinalysis in general practice.</a> BMJ Open. 6, 1-7 (2016).</li><li>. Urisys 1100 Analyzer Available from: <a target="_blank" href="https://diagnostics.roche.com/us/en/products/instruments/urisys-1100.html">https://diagnostics.roche.com/us/en/products/instruments/urisys-1100.html</a> (2020)</li><li>Filippini, D., Lundstr&#246;m, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+strategy+and+instrumental+performance+of+a+computer+screen+photo-assisted+technique+for+the+evaluation+of+a+multi-parameter+colorimetric+test+strip.">Measurement strategy and instrumental performance of a computer screen photo-assisted technique for the evaluation of a multi-parameter colorimetric test strip.</a> Analyst. 131, 111-117 (2006).</li><li>Shen, L., Hagen, J. A., Papautsky, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Point-of-care+colorimetric+detection+with+a+smartphone.">Point-of-care colorimetric detection with a smartphone.</a> Lab on a Chip. 12, 4240-4243 (2012).</li><li>Ra, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Smartphone-Based+Point-of-Care+Urinalysis+under+Variable+Illumination.">Smartphone-Based Point-of-Care Urinalysis under Variable Illumination.</a> IEEE Journal of Translational Engineering in Health and Medicine. 6, 1-11 (2018).</li><li>Yetisen, A. K., Martinez-Hurtado, J. L., Garcia-Melendrez, A., Da Cruz Vasconcellos, F., Lowe, C. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+smartphone+arebeorithm+with+inter-phone+repeatability+for+the+analysis+of+colorimetric+tests.">A smartphone arebeorithm with inter-phone repeatability for the analysis of colorimetric tests.</a> Sensors and Actuators, B: Chemical. 196, 156-160 (2014).</li><li>Wang, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integration+of+cell+phone+imaging+with+microchip+ELISA+to+detect+ovarian+cancer+HE4+biomarker+in+urine+at+the+point-of-care.">Integration of cell phone imaging with microchip ELISA to detect ovarian cancer HE4 biomarker in urine at the point-of-care.</a> Lab on a Chip. 11, 3411-3418 (2011).</li><li>Zhang, D., Liu, Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biosensors+and+bioelectronics+on+smartphone+for+portable+biochemical+detection.">Biosensors and bioelectronics on smartphone for portable biochemical detection.</a> Biosensors and Bioelectronics. 75, 273-284 (2016).</li><li>Choi, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Smartphone-based+urine+reagent+strip+test+in+the+emergency+department.">Smartphone-based urine reagent strip test in the emergency department.</a> Telemedicine and e-Health. 22, 534-540 (2016).</li><li>Kwon, L., Long, K. D., Wan, Y., Yu, H., Cunningham, B. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Medical+diagnostics+with+mobile+devices:+Comparison+of+intrinsic+and+extrinsic+sensing.">Medical diagnostics with mobile devices: Comparison of intrinsic and extrinsic sensing.</a> Biotechnology Advances. 34, 291-304 (2016).</li><li>Vashist, S., Schneider, E., Luong, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Commercial+Smartphone-Based+Devices+and+Smart+Applications+for+Personalized+Healthcare+Monitoring+and+Management.">Commercial Smartphone-Based Devices and Smart Applications for Personalized Healthcare Monitoring and Management.</a> Diagnostics. 4, 104-128 (2014).</li><li>. Inui Available from: <a target="_blank" href="https://www.inuihealth.com/inui/home">https://www.inuihealth.com/inui/home</a> (2020)</li><li>. Healthy.io Available from: <a target="_blank" href="https://healthy.io/">https://healthy.io/</a> (2020)</li><li>. Scanwell Available from: <a target="_blank" href="https://www.scanwellhealth.com">https://www.scanwellhealth.com</a> (2020)</li><li>Smith, G. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Robust+dipstick+urinalysis+using+a+low-cost,+micro-volume+slipping+manifold+and+mobile+phone+platform.">Robust dipstick urinalysis using a low-cost, micro-volume slipping manifold and mobile phone platform.</a> Lab on a Chip. 16, 2069-2078 (2016).</li><li>Du, W., Li, L., Nichols, K. P., Ismagilov, R. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=SlipChip.">SlipChip.</a> Lab on a Chip. 9, 2286-2292 (2009).</li></ol>

Traditional dipstick urinalysis is affordable and convenient but requires manual attention to detail to yield accurate results. Manual dipstick urinalysis is subject to variable lighting conditions, individual color perception differences and cross-contamination. Many clinics and hospitals already have instruments to automate urine dipstick analysis, but the instruments are usually bulky, expensive, and still rely on proper performance of the dip-wipe method. Additionally, these instruments require yearly calibration and...

Urine is a non-invasive source of multiple metabolic indicators of disease or health. Urinalysis, the physical and/or chemical analysis of urine, can be performed quickly to detect renal disease, urinary tract disease, liver disease, diabetes mellitus, and general hydration1. Urinalysis dipsticks are affordable, semi-quantitative diagnostic tools that rely on colorimetric changes to indicate approximate physiological levels. Each dipstick can perform a wide variety of assays including testing for pH, osmolality, hemoglobin/myoglobin, hematuria, leukocyte esterase, glucose, proteinuria, nitrite, ketone, and bilirubin2. The principle of dipstick urinalysis relies on the occurrence of a timed reaction through which a color change on the dipstick pad can be compared to a chart to determine analyte concentration3. Given their affordability and ease of use, dipsticks are one of the most common tools for urinalysis in healthcare.
Traditionally, dipstick urinalysis relies on a trained nurse or medical technician to manually insert the dipstick into a cup of urine sample, wipe off excess urine, and compare the color pads to chart colors at specific times. While the dip-and-wipe method is the gold standard for dipstick analysis, its reliance on human visual assessment limits the quantitative information that can be obtained. Moreover, the two manual steps of dipstick urinalysis &#8211; the dip-wipe step and colorimetric result comparison &#8211; require accurate technique, which limits the possibility of reliable testing in home settings by patients directly. Cross-contamination of the sample pads due to wiping can cause inaccurate color changes. Additionally, inconsistent volumes resulting from the lack of volume control during wiping can result in improper measurement of analyte concentrations. Importantly, the time between dipping the urine (i.e., the start of the assay) and comparison to a chart is critical for accurate analysis of the results and is a huge potential source of human error. The difficulty in manual colorimetric comparison is that many pads must be read at the same time, while some pads are read at different times. Even perfectly timed color comparisons still depend on the visual acuity of the human reader, who may suffer from color blindness or perceive different colors in different lighting environments4. These challenges underscore why clinicians can only rely on dipstick urinalysis performed by trained personnel. However, an automated urinalysis system could address all the aforementioned concerns by eliminating the need for manual dip-wipe steps, incorporating timing controls, and enabling simultaneous color comparisons with calibrated color references. This, in turn, would reduce user error, allowing for possible adoption in home settings.
In the last 20 years, automatic analyzers have been employed to read the results of dipstick urine tests with the same accuracy as or exceeding visual analysis5. Many clinics and doctor offices use such machines to rapidly analyze and print traditional dipstick results. Most urinalysis machines minimize visual inspection errors and ensure consistency in results6. They are easy to use and more efficient than manual inspection but still require the user to perform the dip-wipe method correctly. Hence, these machines have limited ability to be operated by untrained persons such as at-home users; moreover, they are extremely expensive.
Recently, cell phones have emerged as a resourceful tool for various biological colorimetric measurements7,8,9,10, including for urinalysis11,12,13. Given their remote sensing capabilities and high imaging resolution, cell phones have become effective healthcare analytical devices14,15. Indeed, the FDA has cleared several smartphone-based home urine tests16,17,18. Some of the new smartphone-based commercial products incorporate established urinalysis dipsticks, while others feature proprietary colorimetric pads. All such products feature proprietary methods to calibrate for different lighting conditions across different phones types. Still, a problem with these solutions is that the user must manually take a picture at the right time in addition to carrying out a proper manual dip-wipe method (i.e., without cross-contamination). Notably, none of these tests control the volume deposited onto the dipsticks, which we have found can affect the color change19 and interpreted physiological result. The present gaps and costs in the workflows of these devices suggest an additional need to enable a human-free, volume-controlled urine deposition procedure and hands-free dipstick photography.
We describe a protocol for volume-controlled, automated dipstick urinalysis without the need for a manual dip-wipe step. The key to the automated process is a device19 whose underlying principle is based on the SlipChip20 and that transfers liquid between different layers using surface chemistry effects. In brief, the hydrophobic coating on the transfer slide and surrounding plate sleeve force the liquid to move effortlessly through the device and to release onto the dipstick pad once the slide is in its final position, at which point the bottom hydrophobic barrier is replaced with air. Additionally, the coordinated light-blocking box standardizes the lighting conditions, camera angle of view, and the distance for camera focus to ensure accurate and repeatable results that are not influenced by ambient lighting conditions. An accompanying software app automates the capture of images and colorimetric analysis. Following description of the protocol, we provide representative results of the urinalysis test under different conditions. Comparisons with the standard dip-wipe method demonstrate reliability of the proposed method.

<table>
	<tbody>
		<tr>
			<td>Black Cast Acrylic Sheet 
			12&#34; x 24&#34; x 1/8&#34;</td>
			<td>McMaster Carr</td>
			<td>8505K742</td>
			<td>$14.27</td>
		</tr>
		<tr>
			<td>Chart sticker</td>
			<td>Stickeryou.com</td>
			<td></td>
			<td>$12.39</td>
		</tr>
		<tr>
			<td>Clear Scratch- and UV-Resistant Cast Acrylic Sheet 
			12&#34; x 24&#34; x 1/16&#34;</td>
			<td>McMaster Carr</td>
			<td>8560K172</td>
			<td>$9.52</td>
		</tr>
		<tr>
			<td>disposable polyethylene transfer pipet</td>
			<td>Fischer Brand</td>
			<td>13-711-9AM</td>
			<td>lot# 14311021</td>
		</tr>
		<tr>
			<td>Fortus ABS-M30</td>
			<td>Stratasys</td>
			<td>345-42207</td>
			<td>lot# : 108078</td>
		</tr>
		<tr>
			<td>Githut: https://github.com/Iftak/UrineTestApp</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Innovating Science - Replacement Fluids for Urinalysis Diagnostic Test Kit (IS3008)</td>
			<td>Amazon</td>
			<td></td>
			<td>$49</td>
		</tr>
		<tr>
			<td>Nonwhitening Cement for Acrylic 
			Scigrip 4, 4 oz. Can</td>
			<td>MCM</td>
			<td>7517A1</td>
			<td>$9.22</td>
		</tr>
		<tr>
			<td>Rust-Oleum 274232 Repelling treatment base coat-9 oz and top-coat 9-oz , Frosted Clear</td>
			<td>Amazon</td>
			<td>Color: Frosted Clear</td>
			<td>$6.99</td>
		</tr>
		<tr>
			<td>Urinalysis Reagent Strips 10 Panel (100 Tests) MISSION BRAND</td>
			<td>Medimpex United, Inc</td>
			<td>MUI-MS10</td>
			<td>$10.59</td>
		</tr>
	</tbody>
</table>

low-cost, volume-controlled dipstick urinalysis for home-testing

Dipstick urinalysis provides quick and affordable estimations of multiple physiological conditions but requires good technique and training to use accurately. Manual performance of dipstick urinalysis relies on good human color vision, proper lighting control, and error-prone, time-sensitive comparisons to chart colors. By automating the key steps in the dipstick urinalysis test, potential sources of error can be eliminated, allowing self-testing at home. We describe the steps necessary to create a customizable device to perform automated urinalysis testing in any environment. The device is cheap to manufacture and simple to assemble. We describe the key steps involved in customizing it for the dipstick of choice and for customizing a mobile phone app to analyze the results. We demonstrate its use to perform urinalysis and discuss the critical measurements and fabrication steps necessary to ensure robust operation. We then compare the proposed method to the dip-and-wipe method, the gold standard technique for dipstick urinalysis.

Figure 4 demonstrates how the urine is transferred to the dipstick during a urinalysis test. During a typical test, the transfer of urine is not observable because the box occludes the view. Once the sample is deposited in the inlet using a pipette (Step 3.1), it will fill the holes on the slide (Figure 4A). Figure 4B and Figure 4C, respectively, show the progressive movement of the urine across the pla...

Watch this Scientific Journal Video about Low-Cost, Volume-Controlled Dipstick Urinalysis for Home-Testing at JoVE.com

Low-Cost, Volume-Controlled Dipstick Urinalysis for Home-Testing

Dipstick urinalysis is a quick and affordable method of assessing one&#8217;s personal state of health. We present a method to perform accurate, low-cost dipstick urinalysis that removes the primary sources of error associated with traditional dip-and-wipe protocols and is simple enough to be performed by lay users at home.

Dipstick urinalysis provides quick and affordable estimations of multiple physiological conditions but requires good technique and training to use ...

Manual performance of urinalysis dipstick relies on good technique and time-sensitive comparison to chart colors, but automating key steps, we can eliminate potential sources of error and allow home testing. So as a device, it's customizable, inexpensive to manufacture and easy to assemble. It can be used to perform automated urinalysis in any environment.Although critical measurements in fabrication steps are necessary to ensure robust operation, the device implementation is simple and provides accurate and reliable results. After designing the device in an appropriate computer aided design software program, print the inlet cover, top plate, slide and box on a laser cutter into the urinalysis device-based plate on a 3D printer. Use sandpaper to sand the top face area of the base plate between the ledges to roughen the surface.To assemble the inlet and top plate, use acrylic cement to glue the inlet cover onto the top plate where the inlet hole is located. Tape the ledges of the base plate with adhesive tape and holding a can of hydrophobic spray eight to 12 inches away, spray the base plate, top plate, and slide with four to eight coats. The device should have a milky white appearance upon drying.After waiting 12 hours for the base plate to completely dry, remove the tape from the ledges. When the spray has completely dried, align the completed top plate with the ledges of the base plate and use acrylic cement to glue the two pieces together to create the plate sleeve. Then use a clamp to secure the pieces together while drying.While the device is drying, download a QR code from an online QR code generator into the commercially printed vinyl chart sticker from the manufacturer's website. Print the desired code and chart on paper with sticky adhesive backing. Place the QR code 0.17 inches from the right of the first through hole adjacent to the row of through holes and do use clear tape to cover and secure the code to the slide.Then place the vinyl chart sticker to the plate sleeve so that it is aligned with each through hole. To prepare the test, download the urine test mobile application from GitHub and install the app onto a mobile phone. Read the instructions and adjust the analyte names and reading times to be adjusted to match those for the dipstick of interest.Insert the dipstick into the through holes under the plate sleeve and place the plate sleeve inside the box so that the notch is aligned with the box gap. Place the slide into the plate sleeve so that the through holes are aligned with the inlet and place the phone on the top of the box with the back camera lens facing the viewing through hole. Confirm that the phone position will allow an image of the test strip to be acquired through the camera lens and launch the urine test application.Then align the phone so that the dipstick coincides with the boundaries of the black rectangular overlay on screen and click start to begin the test. To analyze a urine sample, use a disposable polyethylene transfer pipette to deposit approximately 500 microliters of urine into the inlet hole and push the slide into the plate sleeve until it is stopped by the base plate top to initiate the test. Here, representative results from a urinalysis test performed with a high-quality smartphone can be observed.As expected, the color of the dipstick did not change in response to water. With the final value for the standard urine, matching with the normal urinary glucose threshold level, and the final value for the high glucose condition being elevated above the normal value. It is important to note that the correct value is not attained for 30 seconds, illustrating the importance of setting the timing readout interval correctly.Using a smartphone with a lower image resolution and flashlight specifications, a significant reduction in the image color and quality of the dipstick panel is observed. The color matching algorithm used by the smartphone application for the urinalysis test, however, yields the same results for the analyte concentrations despite the differences in the physical appearance of the colors of the dipstick pads. Comparing the results captured by an automated urinalysis device to those obtained using the traditional dip-and-wipe method and the commercial urine standard reveals that the accuracy of the automated urinalysis device system depends on the volume transferred to each dipstick pad.Therefore, it is critical that the device is able to accurately and consistently transfer the required urine volume to the dipstick pads. One limitation of this technique is that the hydrophobic coatings may peel with frequent use, thus altering the transferred volume and potentially reducing the accuracy. Additionally, the acrylic bonding may also weakened with repeated testing.The protocol can be used to use with any kind of dipstick with different brands by sending the timers and adjusting the phone app. The method provides increased accuracy of results even when performed by non-trained individuals, suggesting that it as amenable to patient self-testing.

low-cost-volume-controlled-dipstick-urinalysis-for-home-testing

Research

JoVE Journal

Bioengineering

Decellularization and Recellularization of Whole Livers

The liver is a complex organ which requires constant perfusion for delivery of nutrients and oxygen and removal of waste in order to survive1. Efforts to recreate or mimic the liver microstructure with grounds up approach using tissue engineering and microfabrication techniques have not been successful so far due to this design challenge. In addition, synthetic biomaterials used to create scaffolds for liver tissue engineering applications have been limited in inducing tissue regeneration and repair in large part due to the lack of specific cell binding motifs that would induce the proper cell functions2. Decellularized native tissues such blood vessels3and skin4on the other hand have found many applications in tissue engineering, and have provided a practical solution to some of the challenges. The advantage of decellularized native matrix is that it retains, to an extent, the original composition, and the microstructure, hence enhancing cell attachment and reorganization5.
In this work we describe the methods to perform perfusion-decellularization of the liver, such that an intact liver bioscaffold that retains the structure of major blood vessels is obtained. Further, we describe methods to recellularize these bioscaffolds with adult primary hepatocytes, creating a liver graft that is functional in vitro, and has the vessel access necessary for transplantation in vivo.

Perfusion decellularization is a novel technique to produce whole liver scaffolds that retains the organ's extracellular matrix composition and microarchitecture. Herein, the method of preparing whole organ scaffolds using perfusion decellularization and subsequent repopulation with hepatocytes is described. Functional and transplantable liver grafts can be generated using this technique.

The liver is a complex organ which requires constant perfusion for delivery of nutrients and oxygen and removal of waste in order to survive1. Efforts to ...

Low-Cost Cryo-Light Microscopy Stage Fabrication for Correlated Light/Electron Microscopy

The coupling of cryo-light microscopy (cryo-LM) and cryo-electron microscopy (cryo-EM) poses a number of advantages for understanding cellular 
dynamics and ultrastructure. First, cells can be imaged in a near native environment for both techniques. Second, due to the vitrification process, samples are
 preserved by rapid physical immobilization rather than slow chemical fixation. Third, imaging the same sample with both cryo-LM and cryo-EM provides correlation of
 data from a single cell, rather than a comparison of "representative samples". While these benefits are well known from prior studies, the widespread use of correlative 
 cryo-LM and cryo-EM remains limited due to the expense and complexity of buying or building a suitable cryogenic light microscopy stage. Here we demonstrate the 
 assembly, and use of an inexpensive cryogenic stage that can be fabricated in any lab for less than $40 with parts found at local hardware and grocery stores. This 
 cryo-LM stage is designed for use with reflected light microscopes that are fitted with long working distance air objectives. For correlative cryo-LM and cryo-EM 
 studies, we adapt the use of carbon coated standard 3-mm cryo-EM grids as specimen supports. After adsorbing the sample to the grid, previously established protocols 
 for vitrifying the sample and transferring/handling the grid are followed to permit multi-technique imaging. As a result, this setup allows any laboratory with a 
 reflected light microscope to have access to direct correlative imaging of frozen hydrated samples.

We demonstrate the fabrication of a low-cost cryogenic stage designed to fit most reflected light microscopes. This lab-built cryogenic stage enables efficient and reliable correlative imaging between cryo-light and cryo-electron microscopy.

The coupling of cryo-light microscopy (cryo-LM) and cryo-electron microscopy (cryo-EM) poses a number of advantages for understanding cellular 
dynamics ...

Creating Adhesive and Soluble Gradients for Imaging Cell Migration with Fluorescence Microscopy

Cells can sense and migrate towards higher concentrations of adhesive cues such as the glycoproteins of the extracellular matrix and soluble cues such as growth factors. Here, we outline a method to create opposing gradients of adhesive and soluble cues in a microfluidic chamber, which is compatible with live cell imaging. A copolymer of poly-L-lysine and polyethylene glycol (PLL-PEG) is employed to passivate glass coverslips and prevent non-specific adsorption of biomolecules and cells. Next, microcontact printing or dip pen lithography are used to create tracks of streptavidin on the passivated surfaces to serve as anchoring points for the biotinylated peptide arginine-glycine-aspartic acid (RGD) as the adhesive cue. A microfluidic device is placed onto the modified surface and used to create the gradient of adhesive cues (100% RGD to 0% RGD) on the streptavidin tracks. Finally, the same microfluidic device is used to create a gradient of a chemoattractant such as fetal bovine serum (FBS), as the soluble cue in the opposite direction of the gradient of adhesive cues.

A method for the assembly of adhesive and soluble gradients in a microscopy chamber for live cell migration studies is described. The engineered environment combines antifouling surfaces and adhesive tracks with solution gradients and therefore allows one to determine the relative importance of guidance cues.

Cells can sense and migrate towards higher concentrations of adhesive cues such as the glycoproteins of the extracellular matrix and soluble cues such as ...

Determination of the Transport Rate of Xenobiotics and Nanomaterials Across the Placenta using the ex vivo Human Placental Perfusion Model

Decades ago the human placenta was thought to be an impenetrable barrier between mother and unborn child. However, the discovery of thalidomide-induced birth defects and many later studies afterwards proved the opposite. Today several harmful xenobiotics like nicotine, heroin, methadone or drugs as well as environmental pollutants were described to overcome this barrier. With the growing use of nanotechnology, the placenta is likely to come into contact with novel nanoparticles either accidentally through exposure or intentionally in the case of potential nanomedical applications. Data from animal experiments cannot be extrapolated to humans because the placenta is the most species-specific mammalian organ 1. Therefore, the ex vivo dual recirculating human placental perfusion, developed by Panigel et al. in 1967 2 and continuously modified by Schneider et al. in 1972 3, can serve as an excellent model to study the transfer of xenobiotics or particles.
Here, we focus on the ex vivo dual recirculating human placental perfusion protocol and its further development to acquire reproducible results.
The placentae were obtained after informed consent of the mothers from uncomplicated term pregnancies undergoing caesarean delivery. The fetal and maternal vessels of an intact cotyledon were cannulated and perfused at least for five hours. As a model particle fluorescently labelled polystyrene particles with sizes of 80 and 500 nm in diameter were added to the maternal circuit. The 80 nm particles were able to cross the placental barrier and provide a perfect example for a substance which is transferred across the placenta to the fetus while the 500 nm particles were retained in the placental tissue or maternal circuit. The ex vivo human placental perfusion model is one of few models providing reliable information about the transport behavior of xenobiotics at an important tissue barrier which delivers predictive and clinical relevant data.

Determination of the Transport Rate of Xenobiotics and Nanomaterials Across the Placenta using the ex vivo Human Placental Perfusion Model

The ex vivo dual recirculating human placental perfusion model can be used to investigate the transfer of xenobiotics and nanoparticles across the human placenta. In this video protocol we describe the equipment and techniques required for a successful execution of a placenta perfusion.

Decades ago the human placenta was thought to be an impenetrable barrier between mother and unborn child. However, the discovery of thalidomide-induced ...

High Throughput Microfluidic Rapid and Low Cost Prototyping Packaging Methods

In this work, 3 different packaging and assembly techniques are presented. They can be classified into two categories: one-time use and reusable packaging techniques.
The one-time use packaging technique employs UV-based and temperature curing epoxies to connect microtubes to access holes, wire-bonding for integrated circuit connections, and silver epoxy for electrical connections. This method is based on a robust assembly technique that can support relatively high pressure close to 1 psi and does not need any support to strengthen the microfluidic architecture.
Reusable packaging techniques consist of PDMS-based microtube interconnectors and anisotropic adhesive films for electrical connections. These devices are more sensitive and fragile. Consequently, Plexiglas support is added to the microfluidic structure to improve the electrical contact when anisotropic adhesive films are used, and also to strengthen the microfluidic architecture. In addition, a micromanipulator is needed to maintain tubes while using a thin PDMS layer to connect them to the access holes. Different PDMS layer thicknesses, ranging from 0.45-3 mm, are tested to compare the best adherence versus injection rates. Applied injection rates are varied from 50-300 &#956;l/hr for 0.45-3 mm PDMS layers, respectively. These techniques are mainly applicable for low-pressure applications. However, they can be extended for high-pressure ones through plasma-oxygen process to permanently seal the PDMS to glass substrates. The main advantage of this technique, besides the fact that it is reusable, consists of keeping the device observable when the microchannel length is very short (in the range of 3 mm or lower).

In this article we describe different techniques for microfluidic rapid prototyping platforms. The proposed techniques are based on ultraviolet (UV) sensitive and temperature curing epoxies, polydimethylsiloxane (PDMS) based tubing, wire-bonding, and anisotropic adhesive films. The assembling procedures presented are developed for both one-time use devices as well as reusable microfluidic systems.

In this work, 3 different packaging and assembly techniques are presented. They can be classified into two categories: one-time use and reusable packaging ...

Characterization of Complex Systems Using the Design of Experiments Approach: Transient Protein Expression in Tobacco as a Case Study

Plants provide multiple benefits for the production of biopharmaceuticals including low costs, scalability, and safety. Transient expression offers the additional advantage of short development and production times, but expression levels can vary significantly between batches thus giving rise to regulatory concerns in the context of good manufacturing practice. We used a design of experiments (DoE) approach to determine the impact of major factors such as regulatory elements in the expression construct, plant growth and development parameters, and the incubation conditions during expression, on the variability of expression between batches. We tested plants expressing a model anti-HIV monoclonal antibody (2G12) and a fluorescent marker protein (DsRed). We discuss the rationale for selecting certain properties of the model and identify its potential limitations. The general approach can easily be transferred to other problems because the principles of the model are broadly applicable: knowledge-based parameter selection, complexity reduction by splitting the initial problem into smaller modules, software-guided setup of optimal experiment combinations and step-wise design augmentation. Therefore, the methodology is not only useful for characterizing protein expression in plants but also for the investigation of other complex systems lacking a mechanistic description. The predictive equations describing the interconnectivity between parameters can be used to establish mechanistic models for other complex systems.

We describe a design of experiments approach that can be used to determine and model the influence of transgene regulatory elements, plant growth and development parameters, and incubation conditions on the transient expression of monoclonal antibodies and reporter proteins in plants.

Plants provide multiple benefits for the production of biopharmaceuticals including low costs, scalability, and safety. Transient expression offers the ...

Preparation of Light-responsive Membranes by a Combined Surface Grafting and Postmodification Process

In order to modify the surface tension of commercial available track-edged polymer membranes, a procedure of surface-initiated polymerization is presented. The polymerization from the membrane surface is induced by plasma treatment of the membrane, followed by reacting the membrane surface with a methanolic solution of 2-hydroxyethyl methacrylate (HEMA). Special attention is given to the process parameters for the plasma treatment prior to the polymerization on the surface. For example, the influence of the plasma-treatment on different types of membranes (e.g.&#160;polyester, polycarbonate, polyvinylidene fluoride) is studied. Furthermore, the time-dependent stability of the surface-grafted membranes is shown by contact angle measurements. When grafting poly(2-hydroxyethyl methacrylate) (PHEMA) in this way, the surface can be further modified by esterification of the alcohol moiety of the polymer with a carboxylic acid function of the desired substance. These reactions can therefore be used for the functionalization of the membrane surface. For example, the surface tension of the membrane can be changed or a desired functionality as the presented light-responsiveness can be inserted. This is demonstrated by reacting PHEMA with a carboxylic acid functionalized spirobenzopyran unit which leads to a light-responsive membrane. The choice of solvent plays a major role in the postmodification step and is discussed in more detail in this paper. The permeability measurements of such functionalized membranes are performed using a Franz cell with an external light source. By changing the wavelength of the light from the visible to the UV-range, a change of permeability of aqueous caffeine solutions is observed.

A plasma-induced polymerization procedure is described for the surface-initiated polymerization on polymer membranes. Further postmodification of the grafted polymer with photochromic substances is presented with a protocol of conducting permeability measurements of light-responsive membranes.

In order to modify the surface tension of commercial available track-edged polymer membranes, a procedure of surface-initiated polymerization is ...

Rapid and Low-cost Prototyping of Medical Devices Using 3D Printed Molds for Liquid Injection Molding

Biologically inert elastomers such as silicone are favorable materials for medical device fabrication, but forming and curing these elastomers using traditional liquid injection molding processes can be an expensive process due to tooling and equipment costs. As a result, it has traditionally been impractical to use liquid injection molding for low-cost, rapid prototyping applications. We have devised a method for rapid and low-cost production of liquid elastomer injection molded devices that utilizes fused deposition modeling 3D printers for mold design and a modified desiccator as an injection system. Low costs and rapid turnaround time in this technique lower the barrier to iteratively designing and prototyping complex elastomer devices. Furthermore, CAD models developed in this process can be later adapted for metal mold tooling design, enabling an easy transition to a traditional injection molding process. We have used this technique to manufacture intravaginal probes involving complex geometries, as well as overmolding over metal parts, using tools commonly available within an academic research laboratory. However, this technique can be easily adapted to create liquid injection molded devices for many other applications.

We have devised a method for low-cost and rapid prototyping of liquid elastomer rubber injection molded devices by using fused deposition modeling 3D printers for mold design and a modified desiccator as a liquid injection system.

Biologically inert elastomers such as silicone are favorable materials for medical device fabrication, but forming and curing these elastomers using ...

Atomic Force Microscopy Imaging and Force Spectroscopy of Supported Lipid Bilayers

Atomic force microscopy (AFM) is a versatile, high-resolution imaging technique that allows visualization of biological membranes. It has sufficient magnification to examine membrane substructures and even individual molecules. AFM can act as a force probe to measure interactions and mechanical properties of membranes. Supported lipid bilayers are conventionally used as membrane models in AFM studies. In this protocol, we demonstrate how to prepare supported bilayers and characterize their structure and mechanical properties using AFM. These include bilayer thickness and breakthrough force. 
The information provided by AFM imaging and force spectroscopy help define mechanical and chemical properties of membranes. These properties play an important role in cellular processes such as maintaining cell hemostasis from environmental stress, bringing membrane proteins together, and stabilizing protein complexes.

We describe a protocol for preparation of supported lipid bilayers and its characterization using atomic force microscopy and force spectroscopy.

Atomic force microscopy (AFM) is a versatile, high-resolution imaging technique that allows visualization of biological membranes. It has sufficient ...

Visualization of Germinosomes and the Inner Membrane in Bacillus subtilis Spores

The small size of spores and the relatively low abundance of germination proteins, cause difficulties in their microscopic analyses using epifluorescence microscopy. Super-resolution three-dimensional Structured Illumination Microscopy (3D-SIM) is a promising tool to overcome this hurdle and reveal the molecular details of the process of germination of Bacillus subtilis (B. subtilis) spores. Here, we describe the use of a modified SIMcheck (ImageJ)-assistant 3D imaging process and fluorescent reporter proteins for SIM microscopy of B. subtilis spores&#8217; germinosomes, cluster(s) of germination proteins. We also present a (standard)3D-SIM imaging procedure for FM4-64 staining of B. subtilis spore membranes. By using these procedures, we obtained unsurpassed resolution for germinosome localization and show that &#62;80% of B. subtilis KGB80 dormant spores obtained after sporulation on defined minimal MOPS medium have one or two GerD-GFP and GerKB-mCherry foci. Bright foci were also observed in FM4-64 stained spores&#8217; 3D-SIM images suggesting that inner membrane lipid domains of different fluidity likely exist. Further studies that use double labeling procedures with membrane dyes and germinosome reporter proteins to assess co-localization and thus get an optimal overview of the organization of Bacillus germination proteins in the inner spore membrane are possible.

Visualization of Germinosomes and the Inner Membrane in Bacillus subtilis Spores

Germinant receptor proteins cluster in &#8216;germinosomes&#8217; in the inner membrane of Bacillus subtilis spores. We describe a protocol using super resolution microscopy and fluorescent reporter proteins to visualize germinosomes. The protocol also identifies spore inner membrane domains that are preferentially stained with the membrane dye FM4-64.

The small size of spores and the relatively low abundance of germination proteins, cause difficulties in their microscopic analyses using epifluorescence ...