Bias in Ponded Infiltration Estimates Due to Sample Volume and Shape

Prion diseases are a group of fatal transmissible neurological conditions caused by the change in conformation of the normal intrinsic cellular prion protein (PrPC) in to the highly ordered insoluble amyloid state conformer (PrPSC). We present a rapid assay using Aptamers and Resistive Pulse Sensing, RPS, to extract and quantify proteins from complex sample matrices, demonstrate with the quantification of PrPc. We functionalise the surface of superparamagnetic beads, SPBs, with a DNA aptamer. First SPB’s termed P-Beads, are used to pre-concentrate the analyte from a large sample volume. The PrPc protein is then eluted from the P-Beads before aptamer modified sensing beads, S-Beads, are added. The velocity of the S-Beads through the nanopore reveals the concentration of the PrPc protein. The process is done in under an hour and allows the detection of picomol’s of protein. The technique could be easily adopted to the mutated version of the protein and integrated into clinical workflows for the screening of blood donations and transfusions.

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Comparison of the viscoelastic penetration and tensile behaviour of poly(methyl acrylate) and poly(ethyl acrylate)

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19791942 ◽

1979 ◽

Vol 44 (6) ◽

pp. 1942-1948 ◽

Cited By ~ 3

Author(s):

Jaroslav Hrouz ◽

Michal Ilavský ◽

Ivan Havlíček ◽

Karel Dušek

Keyword(s):

Methyl Acrylate ◽

Poisson Ratio ◽

Young Modulus ◽

Ethyl Acrylate ◽

Sample Volume ◽

Viscoelastic Behaviour ◽

Tensile Behaviour ◽

Temperature Superposition ◽

Main Transition

The viscoelastic penetration and tensile behaviour of poly(methyl acrylate) and poly(ethyl acrylate) in the main transition region have been investigated. It was found that the time-temperature superposition could be carried out in the case of the penetration viscoelastic behaviour; the temperature dependence of the penetration and tensile shift factors was the same. The superimposed curves of the penetration and Young modulus allowed us to calculate the dependence of the Poisson ratio and thus to characterize the change in sample volume with deformation. It was demonstrated that the penetration method of determination of the viscoelastic behaviour is equivalent to the tensile method.

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Efficient Preconcentration of Cu2+, Zn2+ and Fe3+ with an Agarose-Schiff Base Sorbent

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc20070908 ◽

2007 ◽

Vol 72 (7) ◽

pp. 908-916 ◽

Cited By ~ 3

Author(s):

Payman Hashemi ◽

Hatam Hassanvand ◽

Hossain Naeimi

Keyword(s):

Schiff Base ◽

Metal Ions ◽

Metal Ion ◽

Good Accuracy ◽

Kinetic Studies ◽

Sample Volume ◽

Effects Of Ph ◽

Glass Column ◽

High Concentrations ◽

Ph Range

Sorption and preconcentration of Cu2+, Zn2+ and Fe3+ on a salen-type Schiff base, 2,2'- [ethane-1,2-diylbis(nitrilomethylidyne)]bis(2-methylphenol), chemically immobilized on a highly crosslinked agarose support, were studied. Kinetic studies showed higher sorption rates of Cu2+ and Fe3+ in comparison with Zn2+. Half-times (t1/2) of 31, 106 and 58 s were obtained for sorption of Cu2+, Zn2+ and Fe3+ by the sorbent, respectively. Effects of pH, eluent concentration and volume, ionic strength, buffer concentration, sample volume and interferences on the recovery of the metal ions were investigated. A 5-ml portion of 0.4 M HCl solution was sufficient for quantitative elution of the metal ions from 0.5 ml of the sorbent packed in a 6.5 mm i.d. glass column. Quantitative recoveries were obtained in a pH range 5.5-6.5 for all the analytes. The volumes to be concentrated exceeding 500 ml, ionic strengths as high as 0.5 mol l-1, and acetate buffer concentrations up to 0.3 mol l-1 for Zn2+ and 0.4 mol l-1 for Cu2+ and Fe3+ did not have any significant effect on the recoveries. The system tolerated relatively high concentrations of diverse ions. Preconcentration factors up to 100 and detection limits of 0.31, 0.16 and 1.73 μg l-1 were obtained for Cu2+, Zn2+ and Fe3+, respectively, for their determination by a flame AAS instrument. The method was successfully applied to the metal ion determinations in several river water samples with good accuracy.

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Comparison of 2 glucose analytical methodologies in immature Kemp’s ridley sea turtles: dry chemistry of plasma versus point-of-care glucometer analysis of whole blood

Journal of Veterinary Diagnostic Investigation ◽

10.1177/10406387211001830 ◽

2021 ◽

pp. 104063872110018

Author(s):

Justin R. Perrault ◽

Michael D. Arendt ◽

Jeffrey A. Schwenter ◽

Julia L. Byrd ◽

Kathryn A. Tuxbury ◽

...

Keyword(s):

Whole Blood ◽

Point Of Care ◽

Sea Turtles ◽

Sample Volume ◽

Specific Reference ◽

Volume Data ◽

Analytical Methodology ◽

Glucose Determination ◽

Kemp's Ridley Sea Turtles ◽

Kemp's Ridley

Blood glucose measurements provide important diagnostic information regarding stress, disease, and nutritional status. Glucose analytical methodologies include dry chemistry analysis (DCA) of plasma and point-of-care (POC) glucometer analysis of whole blood; however, these 2 methods differ in cost, required sample volume, and processing time. Because POC glucometers use built-in equations based on features of mammalian blood to convert whole blood measurements to plasma equivalent units, obtained glucose data must be compared and validated using gold-standard chemistry analytical methodology in reptiles. For in-water, trawl-captured, immature Kemp’s ridley sea turtles ( Lepidochelys kempii) from Georgia, USA, we observed significant, positive agreement between the 2 glucose determination methods; however, the glucometer overestimated glucose concentrations by 1.4 mmol/L on average in comparison to DCA and produced a wider range of results. The discordance of these results suggests that POC glucometer glucose data should be interpreted in the context of methodology- and brand-specific reference intervals along with concurrent packed cell volume data.

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Universal Stokes’s nanomechanical viscometer

Scientific Reports ◽

10.1038/s41598-021-93729-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Komal Chaudhary ◽

Pooja Munjal ◽

Kamal P. Singh

Keyword(s):

Electric Field ◽

Real Time ◽

Sample Volume ◽

Capillary Waves ◽

Small Sample ◽

Medical Applications ◽

Rapid Measurement ◽

Single Lens ◽

Universal Applicability ◽

Small Sample Volume

AbstractAlthough, many conventional approaches have been used to measure viscosity of fluids, most methods do not allow non-contact, rapid measurements on small sample volume and have universal applicability to all fluids. Here, we demonstrate a simple yet universal viscometer, as proposed by Stokes more than a century ago, exploiting damping of capillary waves generated electrically and probed optically with sub-nanoscale precision. Using a low electric field local actuation of fluids we generate quasi-monochromatic propagating capillary waves and employ a pair of single-lens based compact interferometers to measure attenuation of capillary waves in real-time. Our setup allows rapid measurement of viscosity of a wide variety of polar, non-polar, transparent, opaque, thin or thick fluids having viscosity values varying over four orders of magnitude from $$10^{0}{-}10^{4}~\text{mPa} \, \text{s}$$ 10 0 - 10 4 mPa s . Furthermore, we discuss two additional damping mechanisms for nanomechanical capillary waves caused by bottom friction and top nano-layer appearing in micro-litre droplets. Such self-stabilized droplets when coupled with precision interferometers form interesting microscopic platform for picomechanical optofluidics for fundamental, industrial and medical applications.

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Validation of a Novel Diagnostic Approach Combining the VersaTREK™ System for Recovery and Real-Time PCR for the Identification of Mycobacterium chimaera in Water Samples

Microorganisms ◽

10.3390/microorganisms9051031 ◽

2021 ◽

Vol 9 (5) ◽

pp. 1031

Author(s):

Roberto Zoccola ◽

Alessia Di Blasio ◽

Tiziana Bossotto ◽

Angela Pontei ◽

Maria Angelillo ◽

...

Keyword(s):

Real Time ◽

Real Time Pcr ◽

Limit Of Detection ◽

Detection System ◽

Bacterial Load ◽

Microbial Control ◽

Hospital Setting ◽

Sample Volume ◽

Analytical Sensitivity ◽

Initial Water

Mycobacterium chimaera is an emerging pathogen associated with endocarditis and vasculitis following cardiac surgery. Although it can take up to 6–8 weeks to culture on selective solid media, culture-based detection remains the gold standard for diagnosis, so more rapid methods are urgently needed. For the present study, we processed environmental M. chimaera infected simulates at volumes defined in international guidelines. Each preparation underwent real-time PCR; inoculates were placed in a VersaTREK™ automated microbial detection system and onto selective Middlebrook 7H11 agar plates. The validation tests showed that real-time PCR detected DNA up to a concentration of 10 ng/µL. A comparison of the isolation tests showed that the PCR method detected DNA in a dilution of ×102 CFU/mL in the bacterial suspensions, whereas the limit of detection in the VersaTREK™ was <10 CFU/mL. Within less than 3 days, the VersaTREK™ detected an initial bacterial load of 100 CFU. The detection limit did not seem to be influenced by NaOH decontamination or the initial water sample volume; analytical sensitivity was 1.5 × 102 CFU/mL; positivity was determined in under 15 days. VersaTREK™ can expedite mycobacterial growth in a culture. When combined with PCR, it can increase the overall recovery of mycobacteria in environmental samples, making it potentially applicable for microbial control in the hospital setting and also in environments with low levels of contamination by viable mycobacteria.

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Recurrent neural network-based volumetric fluorescence microscopy

Light Science & Applications ◽

10.1038/s41377-021-00506-9 ◽

2021 ◽

Vol 10 (1) ◽

Author(s):

Luzhe Huang ◽

Hanlong Chen ◽

Yilin Luo ◽

Yair Rivenson ◽

Aydogan Ozcan

Keyword(s):

Neural Network ◽

Image Reconstruction ◽

Fluorescence Microscopy ◽

Recurrent Network ◽

Sample Volume ◽

Depth Of Field ◽

Objective Lens ◽

Wide Field ◽

Volumetric Imaging ◽

3D Image Reconstruction

AbstractVolumetric imaging of samples using fluorescence microscopy plays an important role in various fields including physical, medical and life sciences. Here we report a deep learning-based volumetric image inference framework that uses 2D images that are sparsely captured by a standard wide-field fluorescence microscope at arbitrary axial positions within the sample volume. Through a recurrent convolutional neural network, which we term as Recurrent-MZ, 2D fluorescence information from a few axial planes within the sample is explicitly incorporated to digitally reconstruct the sample volume over an extended depth-of-field. Using experiments on C. elegans and nanobead samples, Recurrent-MZ is demonstrated to significantly increase the depth-of-field of a 63×/1.4NA objective lens, also providing a 30-fold reduction in the number of axial scans required to image the same sample volume. We further illustrated the generalization of this recurrent network for 3D imaging by showing its resilience to varying imaging conditions, including e.g., different sequences of input images, covering various axial permutations and unknown axial positioning errors. We also demonstrated wide-field to confocal cross-modality image transformations using Recurrent-MZ framework and performed 3D image reconstruction of a sample using a few wide-field 2D fluorescence images as input, matching confocal microscopy images of the same sample volume. Recurrent-MZ demonstrates the first application of recurrent neural networks in microscopic image reconstruction and provides a flexible and rapid volumetric imaging framework, overcoming the limitations of current 3D scanning microscopy tools.

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Demonstration of a Label-Free and Low-Cost Optical Cavity-Based Biosensor Using Streptavidin and C-Reactive Protein

Biosensors ◽

10.3390/bios11010004 ◽

2020 ◽

Vol 11 (1) ◽

pp. 4

Author(s):

Donggee Rho ◽

Seunghyun Kim

Keyword(s):

Limit Of Detection ◽

Point Of Care ◽

Low Cost ◽

Optical Cavity ◽

Sample Volume ◽

Small Sample ◽

Label Free ◽

C Reactive Protein ◽

Reactive Protein ◽

Cavity Structure

An optical cavity-based biosensor (OCB) has been developed for point-of-care (POC) applications. This label-free biosensor employs low-cost components and simple fabrication processes to lower the overall cost while achieving high sensitivity using a differential detection method. To experimentally demonstrate its limit of detection (LOD), we conducted biosensing experiments with streptavidin and C-reactive protein (CRP). The optical cavity structure was optimized further for better sensitivity and easier fluid control. We utilized the polymer swelling property to fine-tune the optical cavity width, which significantly improved the success rate to produce measurable samples. Four different concentrations of streptavidin were tested in triplicate, and the LOD of the OCB was determined to be 1.35 nM. The OCB also successfully detected three different concentrations of human CRP using biotinylated CRP antibody. The LOD for CRP detection was 377 pM. All measurements were done using a small sample volume of 15 µL within 30 min. By reducing the sensing area, improving the functionalization and passivation processes, and increasing the sample volume, the LOD of the OCB are estimated to be reduced further to the femto-molar range. Overall, the demonstrated capability of the OCB in the present work shows great potential to be used as a promising POC biosensor.

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A tandem giant magnetoresistance assay for one-shot quantification of clinically relevant concentrations of N-terminal pro-B-type natriuretic peptide in human blood

Analytical and Bioanalytical Chemistry ◽

10.1007/s00216-021-03227-5 ◽

2021 ◽

Author(s):

Fanda Meng ◽

Weisong Huo ◽

Jie Lian ◽

Lei Zhang ◽

Xizeng Shi ◽

...

Keyword(s):

Detection Limit ◽

Giant Magnetoresistance ◽

Dynamic Range ◽

Point Of Care ◽

Sample Volume ◽

Small Sample ◽

Broad Dynamic Range ◽

Gmr Sensors ◽

Gmr Sensor ◽

Sample Volume Requirement

AbstractWe report a microfluidic sandwich immunoassay constructed around a dual-giant magnetoresistance (GMR) sensor array to quantify the heart failure biomarker NT-proBNP in human plasma at the clinically relevant concentration levels between 15 pg/mL and 40 ng/mL. The broad dynamic range was achieved by differential coating of two identical GMR sensors operated in tandem, and combining two standard curves. The detection limit was determined as 5 pg/mL. The assay, involving 53 plasma samples from patients with different cardiovascular diseases, was validated against the Roche Cobas e411 analyzer. The salient features of this system are its wide concentration range, low detection limit, small sample volume requirement (50 μL), and the need for a short measurement time of 15 min, making it a prospective candidate for practical use in point of care analysis.

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Complementary Split-Ring Resonator for Microwave Heating of µL Volumes in Microwells in Continuous Microfluidics

Chemosensors ◽

10.3390/chemosensors9070184 ◽

2021 ◽

Vol 9 (7) ◽

pp. 184

Author(s):

Tomislav Markovic ◽

Gertjan Maenhout ◽

Matko Martinic ◽

Bart Nauwelaers

Keyword(s):

Microwave Heating ◽

Ring Resonator ◽

Casting Process ◽

Split Ring Resonator ◽

Sample Volume ◽

Split Ring ◽

Complementary Split Ring Resonator ◽

Microwave Dielectric ◽

Electric Field Direction ◽

Made In

This work presents the design and evaluation of a planar device for microwave heating of liquids in continuous microfluidics (CMF) made in polydimethylsiloxane (PDMS). It deals with volumes in the µL range, which are of high interest and relevance to biologists and chemists. The planar heater in this work is conceived around a complementary split-ring resonator (CSRR) topology that offers a desired electric field direction to—and interaction with—liquids in a microwell. The designed device on a 0.25 mm thick Rogers RO4350B substrate operates at around 2.5 GHz, while a CMF channel and a 2.45 µL microwell are manufactured in PDMS using the casting process. The evaluation of the performance of the designed heater is conducted using a fluorescent dye, Rhodamine B, dissolved in deionized water. Heating measurements are carried out using 1 W of power and the designed device achieves a temperature of 47 °C on a sample volume of 2.45 µL after 20 s of heating. Based on the achieved results, the CSRR topology has a large potential in microwave heating, in addition to the already demonstrated potential in microwave dielectric sensing, all proving the multifunctionality and reusability of single planar microwave-microfluidic devices.

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