Collagen Tubular Airway-on-Chip for Extended Epithelial Culture and Investigation of Ventilation Dynamics

The lower respiratory tract is a hierarchical network of compliant tubular structures that are made from extracellular matrix proteins with a wall lined by an epithelium. While microfluidic airway-on-a-chip models incorporate the effects of shear and stretch on the epithelium, week-long air-liquid-interface culture at physiological shear stresses, the circular cross-section, and compliance of native airway walls have yet to be recapitulated. To overcome these limitations, a collagen tube-based airway model is presented. The lumen is lined with a confluent epithelium during two-week continuous perfusion with warm, humid air while presenting culture medium from the outside and compensating for evaporation. The model recapitulates human small airways in extracellular matrix composition and mechanical microenvironment, allowing for the first time dynamic studies of elastocapillary phenomena associated with regular breathing and mechanical ventilation, as well as their impacts on the epithelium. A case study reveales increasing damage to the epithelium during repetitive collapse and reopening cycles as opposed to overdistension, suggesting expiratory flow resistance to reduce atelectasis. The model is expected to promote systematic comparisons between different clinically used ventilation strategies and, more broadly, to enhance human organ-on-a-chip platforms for a variety of tubular tissues.

Automated fabrication of a scalable heart-on-a-chip device by 3D printing of thermoplastic elastomer nanocomposite and hot embossing

The successful translation of organ-on-a-chip devices requires the development of an automated workflow for device fabrication, which is challenged by the need for precise deposition of multiple classes of materials in micro-meter scaled configurations. Many current heart-on-a-chip devices are produced manually, requiring the expertise and dexterity of skilled operators. Here, we devised an automated and scalable fabrication method to engineer a Biowire II multiwell platform to generate human iPSC-derived cardiac tissues. This high-throughput heart-on-a-chip platform incorporated fluorescent nanocomposite microwires as force sensors, produced from quantum dots and thermoplastic elastomer, and 3D printed on top of a polystyrene tissue culture base patterned by hot embossing. An array of built-in carbon electrodes was embedded in a single step into the base, flanking the microwells on both sides. The facile and rapid 3D printing approach efficiently and seamlessly scaled up the Biowire II system from an 8-well chip to a 24-well and a 96-well format, resulting in an increase of platform fabrication efficiency by 17,5000-69,000% per well. The device's compatibility with long-term electrical stimulation in each well facilitated the targeted generation of mature human iPSC-derived cardiac tissues, evident through a positive force-frequency relationship, post-rest potentiation, and well-aligned sarcomeric apparatus. This system's ease of use and its capacity to gauge drug responses in matured cardiac tissue make it a powerful and reliable platform for rapid preclinical drug screening and development.

Centrifugal microfluidic system for colorimetric sample-to-answer detection of viral pathogens

We describe a microfluidic system for conducting thermal lysis, polymerase chain reaction (PCR) amplification, hybridization, and colorimetric detection of foodborne viral organisms in a sample-to-answer format. The on-chip protocol entails 24 steps which are conducted by a centrifugal platform that allows for actuating liquids pneumatically during rotation and so facilitates automation of the workflow. The microfluidic cartridge is fabricated from transparent thermoplastic polymers and accommodates assay components along with an embedded micropillar array for detection and read-out. A panel of oligonucleotide primers and probes has been developed to perform PCR and hybridization assays that allows for identification of five different viruses, including pathogens such as norovirus and hepatitis A virus (HAV) in a multiplexed format using digoxigenin-labelled amplicons and immunoenzymatic conversion of a chromogenic substrate. Using endpoint detection, we demonstrate that the system can accurately and repetitively (n = 3) discriminate positive and negative signals for HAV at 350 genome copies per μL. As part of the characterization and optimization process, we show that the implementation of multiple (e.g., seven) micropillar arrays in a narrow fluidic pathway can lead to variation (up to 50% or more) in the distribution of colorimetric signal deriving from the assay. Numerical modeling of flow behaviour was used to substantiate these findings. The technology-by virtue of automation-can provide a pathway toward rapid detection of viral pathogens, shortening response time in food safety surveillance, compliance, and enforcement as well as outbreak investigations.

Automated centrifugal microfluidic system for the preparation of adaptor-ligated sequencing libraries

The intensive workload associated with the preparation of high-quality DNA libraries remains a key obstacle toward widespread deployment of sequencing technologies in remote and resource-limited areas. We describe the development of single-use microfluidic devices driven by an advanced pneumatic centrifugal microfluidic platform, the PowerBlade, to automate the preparation of Illumina-compatible libraries based on adaptor ligation methodology. The developed on-chip workflow includes enzymatic DNA fragmentation coupled to end-repair, adaptor ligation, first DNA cleanup, PCR amplification, and second DNA cleanup. This complex workflow was successfully integrated into simple thermoplastic microfluidic devices that are amenable to mass production with injection molding. The system was validated by preparing, on chip, libraries from a mixture of genomic DNA extracted from three common foodborne pathogens (Listeria monocytogenes, Escherichia coli and Salmonella enterica serovar Typhimurium) and comparing them with libraries made via a manual procedure. The two types of libraries were found to exhibit similar quality control metrics (including genome coverage, assembly, and relative abundances) and led to nearly uniform coverage independent of GC content. This microfluidic technology offers a time-saving and cost-effective alternative to manual procedures and robotic-based automation, making it suitable for deployment in remote environments where technical expertise and resources might be scarce. Specifically, it facilitates field practices that involve mid- to low-throughput sequencing, such as tasks related to foodborne pathogen detection, characterization, and microbial profiling.

Facile Fabrication of Flexible Polymeric Membranes with Micro and Nano Apertures over Large Areas

Freestanding, flexible and open through-hole polymeric micro- and nanostructured membranes were successfully fabricated over large areas (>16 cm2) via solvent removal of sacrificial scaffolds filled with polymer resin by spontaneous capillary flow. Most of the polymeric membranes were obtained through a rapid UV curing processes via cationic or free radical UV polymerisation. Free standing microstructured membranes were fabricated across a range of curable polymer materials, including: EBECRYL3708 (radical UV polymerisation), CUVR1534 (cationic UV polymerisation) UV lacquer, fluorinated perfluoropolyether urethane methacrylate UV resin (MD700), optical adhesive UV resin with high refractive index (NOA84) and medical adhesive UV resin (1161-M). The present method was also extended to make a thermal set polydimethylsiloxane (PDMS) membranes. The pore sizes for the as-fabricated membranes ranged from 100 µm down to 200 nm and membrane thickness could be varied from 100 µm down to 10 µm. Aspect ratios as high as 16.7 were achieved for the 100 µm thick membranes for pore diameters of approximately 6 µm. Wide-area and uniform, open through-hole 30 µm thick membranes with 15 µm pore size were fabricated over 44 × 44 mm2 areas. As an application example, arrays of Au nanodots and Pd nanodots, as small as 130 nm, were deposited on Si substrates using a nanoaperture polymer through-hole membrane as a stencil.

Automated sample-to-answer centrifugal microfluidic system for rapid molecular diagnostics of SARS-CoV-2

Testing for SARS-CoV-2 is one of the most important assets in COVID-19 management and mitigation. At the onset of the pandemic, SARS-CoV-2 testing was uniquely performed in central laboratories using RT-qPCR. RT-qPCR relies on trained personnel operating complex instrumentation, while time-to-result can be lengthy (e.g., 24 to 72 h). Now, two years into the pandemic, with the surge in cases driven by the highly transmissible Omicron variant, COVID-19 testing capabilities have been stretched to their limit worldwide. Rapid antigen tests are playing an increasingly important role in quelling outbreaks by expanding testing capacity outside the realm of clinical laboratories. These tests can be deployed in settings where repeat and rapid testing is essential, but they often come at the expense of limited accuracy and sensitivity. Reverse transcription loop-mediated isothermal amplification (RT-LAMP) provides a number of advantages to SARS-CoV-2 testing in standard laboratories and at the point-of-need. In contrast to RT-qPCR, RT-LAMP is performed at a constant temperature, which circumvents the need for thermal cycling and translates into a shorter analysis time (e.g., <1 h). In addition, RT-LAMP is compatible with colorimetric detection, facilitating visualization and read-out. However, even with these benefits, RT-LAMP is not yet clinically deployed at its full capacity. Lack of automation and integration of sample preparation, such as RNA extraction, limits the sensitivity and specificity of the method. Furthermore, the need for cold storage of reagents complicates its use at the point of need. The developments presented in this work address these limitations: We describe a fully automated SARS-CoV-2 detection method using RT-LAMP, which also includes up-front lysis and extraction of viral RNA, performed on a centrifugal platform with active pneumatic pumping, a disposable, all-polymer-based microfluidic cartridge and lyophilized reagents. We demonstrate that the limit of detection of the RT-LAMP assay itself is 0.2 copies per μL using N and E genes as target sequences. When combined with integrated RNA extraction, the assay sensitivity is 0.5 copies per μL, which is highly competitive to RT-qPCR. We tested the automated assay using 12 clinical swab specimens from patients and were able to distinguish positive and negative samples for SARS-CoV-2 within 60 min, thereby obtaining 100% agreement with RT-qPCR results.

Use of Polymer Micropillar Arrays as Templates for Solid-Phase Immunoassays

We investigate the use of periodic micropillar arrays produced by high-fidelity microfabrication with cyclic olefin polymers for solid-phase immunoassays. These three-dimensional (3D) templates offer higher surface-to-volume ratios than two-dimensional substrates, making it possible to attach more antibodies and so increase the signal obtained by the assay. Micropillar arrays also provide the capacity to induce wicking, which is used to distribute and confine antibodies on the surface with spatial control. Micropillar array substrates are modified by using oxygen plasma treatment, followed by grafting of (3-aminopropyl)triethoxysilane for binding proteins covalently using glutaraldehyde as a cross-linker. The relationship between microstructure and fluorescence signal was investigated through variation of pitch (10-50 μm), pillar diameter (5-40 μm), and pillar height (5-57 μm). Our findings suggest that signal intensity scales proportionally with the 3D surface area available for performing solid-phase immunoassays. A linear relationship between fluorescence intensity and microscale structure can be maintained even when the aspect ratio and pillar density both become very high, opening the possibility of tuning assay response by design such that desired signal intensity is obtained over a wide dynamic range compatible with different assays, analyte concentrations, and readout instruments. We demonstrate the versatility of the approach by performing the most common immunoassay formats-direct, indirect, and sandwich-in a qualitative fashion by using colorimetric and fluorescence-based detection for a number of clinically relevant protein markers, such as tumor necrosis factor alpha, interferon gamma (IFN-γ), and spike protein of severe acute respiratory syndrome coronavirus 2. We also show quantitative detection of IFN-γ in serum using a fluorescence-based sandwich immunoassay and calibrated samples with spike-in concentrations ranging from 50 pg/mL to 5 μg/mL, yielding an estimated limit of detection of ∼1 pg/mL for arrays with high micropillar density (11561 per mm2) and aspect ratio (1:11.35).

On-the-Fly Phase Transition and Density Changes of Aqueous Two-Phase Systems on a Centrifugal Microfluidic Platform

This paper describes on-the-fly physical property changes of aqueous two-phase systems (ATPS) in microfluidic devices. The properties and phases of the ATPS are modulated on-demand by using a centrifugal microfluidic device filled with poly(ethylene glycol) (PEG) and dextran (DEX) solutions. By use of the centrifugal force and active pneumatic controls provided by a centrifugal microfluidic platform (CMP), PEG-DEX mixtures are manipulated and processed inside simple thermoplastic microfluidic devices. First, we experimentally demonstrate an on-chip ATPS transition from two phases to a single phase and vice versa by dynamically changing the concentration of the solution to bring ATPS across the binodal curve. We also demonstrate a density modulation scheme by introducing an ATPS solution mixed with sodium diatrizoate hydrate, which allows to increase the liquid density. By adding precisely metered volumes of water, we spontaneously change the density of the solution on the CMP and show that density marker microbeads fall into the solution according to their corresponding densities. The measured densities of ATPS show a good agreement with densities of microbeads and analytical plots. The results presented in this paper highlight the tremendous potential of CMPs for performing complex on-chip processing of ATPS. We anticipate that this method will be useful in applications such as microparticle-based plasma protein analysis and blood cell fractionation.

An automated centrifugal microfluidic assay for whole blood fractionation and isolation of multiple cell populations using an aqueous two-phase system

Fractionating whole blood and separating its constituent components one from another is an essential step in many clinical applications. Currently blood sample handling and fractionation processes remain a predominantly manual task that require well-trained operators to produce reliable and reproducible results. Herein, we demonstrate an advanced on-chip whole human blood fractionation and cell isolation process combining (i) an aqueous two-phase system (ATPS) to create complex separation layers with (ii) a centrifugal microfluidic platform (PowerBlade) with active pneumatic pumping to control and automate the assay. We use a polyethylene glycol (PEG) and dextran (DEX) mixture as the two-phase density gradient media and our automated centrifugal microfluidic platform to fractionate blood samples. Different densities of precisely tuned PEG-DEX solutions were tested to match each of the cell types typically targeted during blood fractionation applications. By employing specially designed microfluidic devices, we demonstrate the automation of the following steps: loading of a whole blood sample on-chip, layering of the blood on the ATPS solution, blood fractionation, precise radial repositioning of the fractionated layers, and finally extraction of multiple, selected fractionated components. Fractionation of up to six distinct layers is shown: platelet-rich plasma, buffy coat, PEG, DEX with neutrophils, red blood cells (RBCs) and high density gradient media (HDGM). Furthermore, through controlled dispensing of HDGM to the fractionation chamber, we show that each of the fractionated layers can be repositioned radially, on-the-fly, without disturbing the interfaces, allowing precise transfer of target fractions and cell types into external vials via a chip-to-world interface. Cell counting analysis and cell viability studies showed equivalence to traditional, manual methods. An overall cell viability greater than 90% of extracted cells demonstrates that the proposed approach is suitable for cell isolation applications. This proof-of-principle demonstration highlights the utility of the proposed system for automated whole blood fractionation and isolation for blood cell applications. We anticipate that the proposed approach will be a useful tool for many clinical applications such as standard cell isolation procedures and other bioanalytical assays (e.g., circulating tumor cells, and cell and gene therapy).

Multifunctional magnetic nanoparticle cloud assemblies for in situ capture of bacteria and isolation of microbial DNA

We investigate the formation of suspended magnetic nanoparticle (MNP) assemblies (M-clouds) and their use for in situ bacterial capture and DNA extraction. M-clouds are obtained as a result of magnetic field density variations when magnetizing an array of micropillars coated with a soft ferromagnetic NiP layer. Numerical simulations suggest that the gradient in the magnetic field created by the pillars is four orders of magnitude higher than the gradient generated by the external magnets. The pillars therefore serve as the sole magnetic capture sites for MNPs which accumulate on opposite sides of each pillar facing the magnets. Composed of loosely aggregated MNPs, the M-cloud can serve as a porous capture matrix for target analyte flowing through the array. The concept is demonstrated by using a multifunctional M-cloud comprising immunomagnetic NPs (iMNPs) for capture of Escherichia coli O157:H7 from river water along with silica-coated NPs for subsequent isolation and purification of microbial DNA released upon bacterial lysis. Confocal microscopy imaging of fluorescently labeled iMNPs and E. coli O157:H7 reveals that bacteria are trapped in the M-cloud region between micropillars. Quantitative assessment of in situ bacterial capture, lysis and DNA isolation using real-time polymerase chain reaction shows linear correlation between DNA output and input bacteria concentration, making it possible to confirm E. coli 0157:H7 at 10³ cells per mL. The M-cloud method further provides one order of magnitude higher DNA output concentrations than incubation of the sample with iMNPs in a tube for an equivalent period of time (e.g., 10 min). Results from assays performed in the presence of Listeria monocytogenes (at 10⁶ cells per mL each) suggest that non-target organisms do not affect on-chip E. coli capture, DNA extraction efficiency and quality of the eluted sample.

Real-time monitoring of bead-based DNA hybridization in a microfluidic system: study of amplicon hybridization behavior on solid supports

DNA hybridization phenomena occurring on solid supports are not understood as clearly as aqueous phase hybridizations and mathematical models cannot predict some empirically obtained results. Ongoing research has identified important parameters but remains incomplete to accurately account for all interactions. It has previously been shown that the length of the overhanging (dangling) end of the target DNA strand following hybridization to the capture probe is correlated to interactions with the complementary strand in solution which can result in unbinding of the target and its release from the surface. We have developed an instrument for real-time monitoring of DNA hybridization on spherical particles functionalized with oligonucleotide capture probes and arranged in the form of a tightly packed monolayer bead bed inside a microfluidic cartridge. The instrument is equipped with a pneumatic module to mediate displacement of fluid on the cartridge. We compared this system to both conventional (passive) and centrifugally-driven (active) microfluidic microarray hybridization on glass slides to establish performance levels for the detection of single nucleotide polymorphisms. The system was also used to study the effect of the dangling end's length in real-time when the immobilized target DNA is exposed to the complementary strand in solution. Our findings indicate that increasing the length of the dangling end leads to desorption of target amplicons from bead-bound capture probes at a rate approaching that of the initial hybridization process. Finally, bead bed hybridization was performed with Streptococcus agalactiae cfb gene amplicons obtained from randomized clinical samples, which allowed for identification of group B streptococci within 5-15 min. The methodology presented here is useful for investigating competitive hybridization mechanisms on solid supports and to rapidly validate the suitability of microarray capture probes.

Evaporation-Driven Water-in-Water Droplet Formation

We present new observations of aqueous two-phase system (ATPS) thermodynamic and interfacial phenomena that occur inside sessile droplets due to water evaporation. Sessile droplets that contain polymeric solutions, which are initially in equilibrium in a single phase, are observed at their three-phase liquid-solid-air contact line. As evaporation of a sessile droplet proceeds, we find that submicron secondary water-in-water (W/W) droplets emerge spontaneously at the edges of the mother sessile droplet due to the resulting phase separation from water evaporation. To understand this phenomenon, we first study the secondary W/W droplet formation process on different substrate materials, namely, glass, polycarbonate (PC), thermoplastic elastomer (TPE), poly(dimethylsiloxane)-coated glass slide (PDMS substrate), and Teflon-coated glass slide (Teflon substrate), and show that secondary W/W droplet formation arises only in lower-contact-angle substrates near the three-phase contact line. Next, we characterize the size of the emergent secondary W/W droplets as a function of time. We observe that W/W drops are formed, coalesced, aligned, and trapped along the contact line of the mother droplet. We demonstrate that this W/W multiple emulsion system can be used to encapsulate magnetic particles and blood cells, and achieve size-based separation. Finally, we show the applicability of this system for protein sensing. This is the first experimental observation of evaporation-induced secondary W/W droplet generation in a sessile droplet. We anticipate that the phenomena described here may be applicable to some biological assay applications, for example, biomarker detection, protein sensing, and point-of-care diagnostic testing.

Buoyancy-driven step emulsification on pneumatic centrifugal microfluidic platforms

We present here a new method for controlling the droplet size in step emulsification processes on a centrifugal microfluidic platform, which, in addition to the centrifugal force, uses pneumatic actuation for fluid displacement. We highlight the importance of the interplay between buoyancy effects and the flow rate at the step junction, and provide a simple analytical model relating these two quantities to the size of the droplets. Numerical models as well as experiments with water-in-oil emulsions are performed in support of the proposed model.

Methylation Specific Multiplex Droplet PCR using Polymer Droplet Generator Device for Hematological Diagnostics

A multiplexed droplet PCR (mdPCR) workflow and detailed protocol for determining epigenetic-based white blood cell (WBC) differential count is described, along with a thermoplastic elastomer (TPE) microfluidic droplet generation device. Epigenetic markers are used for WBC subtyping which is of important prognostic value in different diseases. This is achieved through the quantification of DNA methylation patterns of specific CG-rich regions in the genome (CpG loci). In this paper, bisulfite-treated DNA from peripheral blood mononuclear cells (PBMCs) is encapsulated in droplets with mdPCR reagents including primers and hydrolysis fluorescent probes specific for CpG loci that correlate with WBC sub-populations. The multiplex approach allows for the interrogation of many CpG loci without the need for separate mdPCR reactions, enabling more accurate parametric determination of WBC sub-populations using epigenetic analysis of methylation sites. This precise quantification can be extended to different applications and highlights the benefits for clinical diagnosis and subsequent prognosis.

Detection of renal biomarkers in chronic kidney disease using microfluidics: progress, challenges and opportunities

Chronic kidney disease (CKD) typically evolves over many years in a latent period without clinical signs, posing key challenges to detection at relatively early stages of the disease. Accurate and timely diagnosis of CKD enable effective management of the disease and may prevent further progression. However, long turn-around times of current testing methods combined with their relatively high cost due to the need for established laboratory infrastructure, specialized instrumentation and trained personnel are drawbacks for efficient assessment and monitoring of CKD, especially in underserved and resource-poor locations. Among the emerging clinical laboratory approaches, microfluidic technology has gained increasing attention over the last two decades due to the possibility of miniaturizing bioanalytical assays and instrumentation, thus potentially improving diagnostic performance. In this article, we review current developments related to the detection of CKD biomarkers using microfluidics. A general trend in this emerging area is the search for novel, sensitive biomarkers for early detection of CKD using technology that is improved by means of microfluidics. It is anticipated that these innovative approaches will be soon adopted and utilized in both clinical and point-of-care settings, leading to improvements in life quality of patients.

The Ecobiomics project: Advancing metagenomics assessment of soil health and freshwater quality in Canada

Transformative advances in metagenomics are providing an unprecedented ability to characterize the enormous diversity of microorganisms and invertebrates sustaining soil health and water quality. These advances are enabling a better recognition of the ecological linkages between soil and water, and the biodiversity exchanges between these two reservoirs. They are also providing new perspectives for understanding microorganisms and invertebrates as part of interacting communities (i.e. microbiomes and zoobiomes), and considering plants, animals, and humans as holobionts comprised of their own cells as well as diverse microorganisms and invertebrates often acquired from soil and water. The Government of Canada's Genomics Research and Development Initiative (GRDI) launched the Ecobiomics Project to coordinate metagenomics capacity building across federal departments, and to apply metagenomics to better characterize microbial and invertebrate biodiversity for advancing environmental assessment, monitoring, and remediation activities. The Project has adopted standard methods for soil, water, and invertebrate sampling, collection and provenance of metadata, and nucleic acid extraction. High-throughput sequencing is located at a centralized sequencing facility. A centralized Bioinformatics Platform was established to enable a novel government-wide approach to harmonize metagenomics data collection, storage and bioinformatics analyses. Sixteen research projects were initiated under Soil Microbiome, Aquatic Microbiome, and Invertebrate Zoobiome Themes. Genomic observatories were established at long-term environmental monitoring sites for providing more comprehensive biodiversity reference points to assess environmental change.

Centrifugal microfluidic lab-on-a-chip system with automated sample lysis, DNA amplification and microarray hybridization for identification of enterohemorrhagic Escherichia coli culture isolates

Automated workflow that starts with a colony isolate and ends with a fluorescence signal on a DNA microarray.

Extraction of nucleic acids from blood: unveiling the potential of active pneumatic pumping in centrifugal microfluidics for integration and automation of sample preparation processes

This paper describes the development of an on-chip nucleic acid (NA) extraction assay from whole blood using a centrifugal microfluidic platform that allows for pneumatic actuation of liquids during rotation. The combination of pneumatic and centrifugal forces makes it possible to perform fluidic operations without the need for integrating active control elements on the microfluidic cartridge. The cartridge is fabricated from thermoplastic polymers (e.g., Zeonor 1060R) and features a simple design that is compatible with injection molding. In addition, the cartridge is interfaced with two external vials for off-chip storage of the blood sample and retrieval of the eluted NA solution, respectively. On-chip capture of NAs is performed using an embedded solid-phase extraction matrix composed of commercial glass microfiber filters (Whatman GF/D and GF/F). The yield of the automated, on-chip extraction protocol, determined by measuring absorbance at 260 nm, is comparable to some of the best manually operated kits (e.g., Qiagen QIAamp DNA Mini Kit) while providing low assay-to-assay variability due to the high level of control provided by the platform for each processing step. The A260/A280 and A260/A230 ratios of the absorbance spectra also reveal that protein contamination of the sample is negligible. The capability of the pneumatic platform to circulate air flux through the microfluidic conduit was used to dry leftover ethanol residues retained in the capture matrix during washing. This method, applied in combination with localized heating, proved effective for reducing ethanol contamination in eluted samples from ∼12% to 1% (v/v).

Two-level submicron high porosity membranes (2LHPM) for the capture and release of white blood cells (WBCs)

A method modifying a vacuum-assisted UV micro-molding (VAUM) process is proposed for the fabrication of polymer two-level submicron high porosity membranes (2LHPM). The modified process allows for the fabrication of robust, large-area membranes over 5 × 5 cm2 with a hierarchical architecture made from a 200 nm-thick layer having submicron level pores (as small as 500 nm) supported by a 20 μm-thick layer forming a microporous structure with 10-15 μm diameter pores. The fabricated freestanding membranes are flexible and mechanically robust enough for post manipulation and filtration of cell samples. Very high white blood cell (WBC) capture efficiencies (≈97%) from healthy blood samples after red blood cell (RBC) lysis are demonstrated using a 3D-printed filter cartridge incorporated within these 2LHPM. A high release efficiency of ≈95% is also proved using the same setup. Finally, on-filter multistep immunostaining of captured cells is also shown.

Epigenetic subtyping of white blood cells using a thermoplastic elastomer-based microfluidic emulsification device for multiplexed, methylation-specific digital droplet PCR

Digital droplet PCR for epigenetic leukocyte subtyping from clinically relevant samples is implemented using a thermoplastic elastomer microfluidic droplet generator as a first step towards an economical, customizable and easily deployable system.

Abstract 1562: Clusters of circulating tumor cells were selectively isolated in the blood of 12/12 epithelial ovarian cancer patients using facile gravity-flow-based filtration method adapted to clinical use

Background

The presence of circulating tumor cells (CTCs) in blood is correlated with disease progression in many cancers. Their prognosis value in ovarian cancer is still under debate.1 CTCs are heterogeneous in size and marker expression, and sub-populations with various metastatic potentials have been identified. CTC clusters, although rare and difficult to isolate, have emerged as a possible driver of metastasis owing to ~50-time higher metastatic potential than single CTCs.2 Only few methods have emerged to capture clusters, and are often complex and cumbersome, limiting our understanding of the role of clusters in metastasis. Here, we present a new filtration method for the selective capture of CTC clusters from blood and found clusters in 12/12 epithelial ovarian cancer (EOC) patients.

Method

Cluster capture was performed by filtration using a 3D printed cartridge3 and filters4 with pore diameters of 8, 10, 12, 15, 20 or 28 μm. We developed a gravity-driven process, generating reduced shear stress, and optimized capture using blood (1:6, v/v, in PBS) spiked with OV-90 and OVCAR-3 ovarian cancer single cells and clusters. Blood samples from 12 EOC patients were filtered. Clusters can be stained and imaged on the filter, or released for downstream analysis.

Results

Using the gravity-setup, we were able to selectively capture clusters with good integrity and with a rate that outperforms other technologies to the best of our knowledge. Viable CTC clusters, with 2 to &gt;100 cells, were captured from 12/12 EOC patients. Their size distribution was surprisingly similar between patients. Small clusters (2-3 cells) were the most frequent, and this frequency decreased as their size increased.

The molecular characterization of the captured clusters revealed a low and localized, heterogeneous expression of EpCAM (epithelial cell adhesion molecule), in combination with a widespread expression of c-MET (hepatocyte growth factor receptor) in all patients, suggesting a mesenchymal-like profile.

Conclusion

Using the gravity-filtration setup, CTC clusters were captured from the blood of all patients tested, suggesting that clusters are much more widespread than anticipated, and are in fact the norm rather than the exception. The cluster size distribution was conserved between patients with small clusters dominating, and some rare, very large clusters. Cluster staining revealed a mesenchymal profile, in agreement with a higher metastatic potential. Together, these results suggest that clusters should significantly contribute to disease progression, a hypothesis, which may be explored using our facile and selective method.

References

1. Y. Zhou, et al. PLoS ONE 2015, 10, e0130873.

2. N. Aceto, et al. Cell 2014, 158, 1110.

3. A. Meunier, et al. Anal. Chem. 2016, 88, 8510.

4. J. A. Hernandez-Castro, et al. LOC 2017, 17, 1960

Citation Format: Anne Meunier, Sara Kheireddine, J. Alejandro Hernández-Castro, Benjamin Péant, Diane Provencher, Anne-Marie Mes-Masson, Teodor Veres, David Juncker. Clusters of circulating tumor cells were selectively isolated in the blood of 12/12 epithelial ovarian cancer patients using facile gravity-flow-based filtration method adapted to clinical use [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1562.

Note: 4-bounce neutron polarizer for reflectometry applications

A neutron polarizer using four successive reflections on m = 2.5 supermirrors was built and installed at the GINA neutron reflectometer at the Budapest Neutron Centre. This simple setup exhibits 99.6% polarizing efficiency with 80% transmitted intensity of the selected polarization state. Due to the geometry, the higher harmonics in the incident beam are filtered out, while the optical axis of the beam remains intact for easy mounting and dismounting the device in an existing experimental setup.

Rapid Screening and Identification of Living Pathogenic Organisms via Optimized Bioorthogonal Non-canonical Amino Acid Tagging

Pathogenic bacteria can be a major cause of illness from environmental sources as well as the consumption of contaminated products, giving rise to public health concerns globally. The surveillance of such living organisms in food and water supplies remains an important challenge in mitigating their deleterious societal effects. Here, we have developed an optimized bioorthogonal non-canonical amino acid tagging approach to the imaging, capture, and interrogation of shigatoxigenic/verotoxigenic Escherichia coli (VTEC) and Listeria that enables the distinction between living wild-type pathogenic bacteria. The approaches utilize homopropargylglycine (HPG), as well as optimized growth media, that restricts endogenous methionine biosynthesis in a variety of species of public health concern. Endogenous methionine residues are then replaced with HPG, which can then be modified using a myriad of compatible bioorthogonal reactions for tagging of exclusively live bacteria. The methods reported allow for the very rapid screening and identification of living pathogenic organisms.

Abstract 2912: Size based enrichment and sorting of Ov90 cancer cells and clusters with a new multistage filtration cartridge reveals distinct phenotypes

Background: Circulating tumor cells (CTCs) are released in blood from the primary tumor, but although very heterogeneous both in size and marker expression, are very rare and provide information not available from the primary tumor. The identification of CTC cells and clusters could advance our understanding of metastasis and help personalize therapy.1,2 Notably, CTC clusters were shown to have a higher metastatic potential than single cells3 but the process remains poorly understood.

We present a multistage filtration system with pore sizes from 20 down to 8 μm for the size-selective enrichment of Ov90 ovarian cancer cells and clusters from blood. Each captured cell population was released, cultured and characterized independently.

Methods: We developed a 3D printed multistage filtration cartridge and polymer filters with 20, 15, 12, 10 and 8 μm-diameter pores. Filters were stacked from 20 (top) to 8 μm (bottom) and used to enrich and sort Ov-90 cells spiked in 1:6 mL of blood:PBS. Captured cells were released by removing individual filters from the cartridge, reverse flowing OSE medium, and then cultured separately.

Results: Ov-90 clusters were found mostly on the top filter (20 μm) and interestingly, few small clusters (3-4 cells) were found on the 8 and 10 μm filters, suggesting alignment of cluster cells as they pass through the pores.4 Cell and nucleus diameters were measured, and a general correlation was found between filter pore size and cell and nucleus size. Interestingly, nucleus size was found to be the single most significant parameter in determining passage of single cells and small clusters through pores.

Following cell culture, two distinct phenotypes were observed: cell captured on small pore filters (8-12 μm) grew primarily in a monolayer. Cells captured on filters with larger pores (15-20 μm) first grew as monolayer, but rapidly formed cell aggregates that subsequently detached from the surface. Staining for E-Cadherin, a cell-cell adhesion protein, revealed a loss of expression of cells from filter with larger pores.

Conclusion: We developed a new multistage filtration method and selectively enriched and sorted cells based primarily on their nucleus size. We identified two Ov-90 populations with different growth behaviors with low E-cadherin expression on the cells forming clusters, which is known to correlate with metastasis. The application of multistage filters may also reveal different CTC populations based on nucleus and cell size.

References:

(1) Baccelli, I. et al. A. Nat. Biotech. 2013, 31, 539-544.

(2) Pecot, C. V. et al. Cancer discovery 2011, 1, 580-586.

(3) Cheung, K. J. et al. Proc. Natl. Acad. Sci. U.S.A. 2016, 113, E854-E863.

(4) Au, S. H. et al. Proc. Natl. Acad. Sci. U.S.A. 2016, 113, 4947-4952.

Citation Format: Anne Meunier, Sara kheireddine, J. Alejandro Hernández-Castro, Teodor Veres, David Juncker. Size based enrichment and sorting of Ov90 cancer cells and clusters with a new multistage filtration cartridge reveals distinct phenotypes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2912. doi:10.1158/1538-7445.AM2017-2912

Fabrication of large-area polymer microfilter membranes and their application for particle and cell enrichment

A vacuum assisted UV micro-molding (VAUM) process is proposed for the fabrication of freestanding and defect-free polymer membranes based on a UV-curable methacrylate polymer (MD 700). VAUM is a highly flexible and powerful method for fabricating low cost, robust, large-area membranes over 9 × 9 cm² with pore sizes from 8 to 20 μm in diameter, 20 to 100 μm in thickness, high aspect ratio (the thickness of the polymer over the diameter of the hole is up to 15 : 1), high porosity, and a wide variety of geometrical characteristics. The fabricated freestanding membranes are flexible while mechanically robust enough for post manipulation and handling, which allows them to be cut and integrated as a plastic cartridge onto thermoplastic 3D microfluidic devices with single or double filtration stages. Very high particle capture efficiencies (≈98%) have been demonstrated in the microfluidic devices integrated with polymer membranes, even when the size of the beads is very close to the size of the pores of the microfilter. About 85% of the capture efficiency has been achieved in cancer cell trapping experiments, in which a breast cancer cell line (MDA-MB-231) spiked with phosphate-buffered saline buffer when the pore size of the filter is 8 μm and the device is operated at a flow rate of 0.1 mL min^-1.

Combination of Mechanical and Molecular Filtration for Enhanced Enrichment of Circulating Tumor Cells

Circulating tumor cells (CTCs) have been linked to cancer progression but are difficult to isolate, as they are very rare and heterogeneous, covering a range of sizes and expressing different molecular receptors. Filtration has emerged as a simple and powerful method to enrich CTCs but only captures cells above a certain size regardless of molecular characteristics. Here, we introduce antibody-functionalized microfilters to isolate CTCs based on both size and surface receptor expression. We present a 3D printed filtration cartridge with microfabricated polymer filters with 8, 10, 12, 15, or 20 μm-diameter pores. Pristine filters were used to optimize sample dilution, rinsing protocol, flow rate, and pore size, leading to >80% for the recovery of spiked cancer cells with very low white blood cell contamination (<1000). Then, filters were functionalized with antibodies against either epithelial cell adhesion molecule (EpCAM) or epidermal growth factor receptor (EGFR) and the cartridges were used to enrich breast (MDA-MB-231, MCF-7) and renal (786-O, A-498) cancer cells expressing various levels of EpCAM and EGFR. Cancer cells were spiked into human blood, and when using filters with antibodies specific to a molecular receptor expressed on a cell, efficiency was increased to >96%. These results suggest that filtration can be optimized to target specific CTC characteristics such as size and receptor expression and that a diverse range of CTCs may be captured using particular combinations of pore size, filtration parameters, and antibody functionalization.

Polymer-based microfluidic chip for rapid and efficient immunomagnetic capture and release of Listeria monocytogenes

Infections caused by foodborne pathogens such as Listeria monocytogenes pose a threat to public health while timely detection is challenging due to pathogen low numbers. The development of robust and efficient sample preparation techniques is crucial to improve detection sensitivity and workflow. Immunomagnetic separation using magnetic nanoparticles (MNPs) is attractive, as it can efficiently capture target cells. For food safety applications, a platform is needed to rapidly process large sample volumes, allowing capture and release of target bacteria conjugated to immunomagnetic nanoparticles (IMNPs). Herein, we demonstrate a method for magnetic capture and release of bacteria-IMNPs complex based on a 3D magnetic trap integrated on a polymeric microfluidic device. The 3D magnetic capture region consist of a dense array of high-aspect ratio (3 : 1) cylindrical pillars embossed in thermoplastic polymer and coated with soft ferromagnetic nickel by an electroless deposition technique. This allows the generation of strong and switchable magnetic capture regions due to the very low remanence of the nickel shell. We propose and validate an optimized configuration of capture regions for efficient localized capture and rapid release of MNPs and IMNPs conjugated to L. monocytogenes. A maximum recovery rate for MNPs corresponded to 91% while a maximum capture efficiency of 30% was obtained for live bacteria, with a minimum detectable sample concentration of ~10 cfu ml(-1) in 1 ml volume using plate-culture method. We believe that the flexible design and low-cost fabrication process of the proposed system will allow rapid sample preparation for applications beyond food and water safety, including point-of-care diagnosis.

Enhancing the Detection of Giardia duodenalis Cysts in Foods by Inertial Microfluidic Separation

The sensitivity and specificity of current Giardia cyst detection methods for foods are largely determined by the effectiveness of the elution, separation, and concentration methods used. The aim of these methods is to produce a final suspension with an adequate concentration of Giardia cysts for detection and a low concentration of interfering food debris. In the present study, a microfluidic device, which makes use of inertial separation, was designed and fabricated for the separation of Giardia cysts. A cyclical pumping platform and protocol was developed to concentrate 10-ml suspensions down to less than 1 ml. Tests involving Giardia duodenalis cysts and 1.90-μm microbeads in pure suspensions demonstrated the specificity of the microfluidic chip for cysts over smaller nonspecific particles. As the suspension cycled through the chip, a large number of beads were removed (70%) and the majority of the cysts were concentrated (82%). Subsequently, the microfluidic inertial separation chip was integrated into a method for the detection of G. duodenalis cysts from lettuce samples. The method greatly reduced the concentration of background debris in the final suspensions (10-fold reduction) in comparison to that obtained by a conventional method. The method also recovered an average of 68.4% of cysts from 25-g lettuce samples and had a limit of detection (LOD) of 38 cysts. While the recovery of cysts by inertial separation was slightly lower, and the LOD slightly higher, than with the conventional method, the sample analysis time was greatly reduced, as there were far fewer background food particles interfering with the detection of cysts by immunofluorescence microscopy.

Active pneumatic control of centrifugal microfluidic flows for lab-on-a-chip applications

This paper reports a novel method of controlling liquid motion on a centrifugal microfluidic platform based on the integration of a regulated pressure pump and a programmable electromechanical valving system. We demonstrate accurate control over the displacement of liquids within the system by pressurizing simultaneously multiple ports of the microfluidic device while the platform is rotating at high speed. Compared to classical centrifugal microfluidic platforms where liquids are solely driven by centrifugal and capillary forces, the method presented herein adds a new degree of freedom for fluidic manipulation, which represents a paradigm change in centrifugal microfluidics. We first demonstrate how various core microfluidic functions such as valving, switching, and reverse pumping (i.e., against the centrifugal field) can be easily achieved by programming the pressures applied at dedicated access ports of the microfluidic device. We then show, for the first time, that the combination of centrifugal force and active pneumatic pumping offers the possibility of mixing fluids rapidly (~0.1 s) and efficiently based on the creation of air bubbles at the bottom of a microfluidic reservoir. Finally, the suitability of the developed platform for performing complex bioanalytical assays in an automated fashion is demonstrated in a DNA harvesting experiment where recovery rates of about 70% were systematically achieved. The proposed concept offers the interesting prospect to decouple basic microfluidic functions from specific material properties, channel dimensions and fabrication tolerances, surface treatments, or on-chip active components, thus promoting integration of complex assays on simple and low-cost microfluidic cartridges.

Twin tubular pinch effect in curving confined flows

Colloidal suspensions of buoyancy neutral particles flowing in circular pipes focus into narrow distributions near the wall due to lateral migration effects associated with fluid inertia. In curving flows, these distributions are altered by Dean currents and the interplay between Reynolds and Dean numbers is used to predict equilibrium positions. Here, we propose a new description of inertial lateral migration in curving flows that expands current understanding of both focusing dynamics and equilibrium distributions. We find that at low Reynolds numbers, the ratio δ between lateral inertial migration and Dean forces scales simply with the particle radius, coil curvature and pipe radius as . A critical value δ_c = 0.148 of this parameter is identified along with two related inertial focusing mechanisms. In the regime below δ_c, coined subcritical, Dean forces generate permanently circulating, twinned annuli, each with intricate equilibrium particle distributions including eyes and trailing arms. At δ > δ_c (supercritical regime) inertial lateral migration forces are dominant and particles focus to a single stable equilibrium position.

Rapid and multiplex detection of Legionella's RNA using digital microfluidics

Despite recent advances in the miniaturization and automation of biosensors, technologies for on-site monitoring of environmental water are still at an early stage of development. Prevention of outbreaks caused by pathogens such as Legionella pneumophila would be facilitated by the development of sensitive and specific bioanalytical assays that can be easily integrated in miniaturized fluidic handling systems. In this work, we report on the integration of an amplification-free assay in digital microfluidics (DMF) for the detection of Legionella bacteria based on targeting 16s rRNA. We first review the design of the developed DMF devices, which provide the capability to store up to one hundred nL-size droplets simultaneously, and discuss the challenges involved with on-chip integration of the RNA-based assay. By optimizing the various steps of the assay, including magnetic capture, hybridization duration, washing steps, and assay temperature, a limit of detection as low as 1.8 attomoles of synthetic 16s rRNA was obtained, which compares advantageously to other amplification-free detection systems. Finally, we demonstrate the specificity of the developed assay by performing multiplex detection of 16s rRNAs from a pathogenic and a non-pathogenic species of Legionella. We believe the developed DMF devices combined with the proposed detection system offers new prospects for the deployment of rapid and cost-effective technologies for on-site monitoring of pathogenic bacteria.

From cellular lysis to microarray detection, an integrated thermoplastic elastomer (TPE) point of care Lab on a Disc

We present an all-thermoplastic integrated sample-to-answer centrifugal microfluidic Lab-on-Disc system (LoD) for nucleic acid analysis. The proposed CD system and engineered platform were employed for analysis of Bacillus atrophaeus subsp. globigii spores. The complete assay comprised cellular lysis, polymerase chain reaction (PCR) amplification, amplicon digestion, and microarray hybridization on a plastic support. The fluidic robustness and operating efficiency of the assay were ensured through analytical optimization of microfluidic tools enabling beneficial implementation of capillary valves and accurate control of all flow timing procedures. The assay reliability was further improved through the development of two novel microfluidic strategies for reagents mixing and flow delay on the CD platform. In order to bridge the gap between the proof-of-concept LoD and production prototype demonstration, low-cost thermoplastic elastomer (TPE) was selected as the material for CD fabrication and assembly, allowing the use of both, high quality hot-embossing and injection molding processes. Additionally, the low-temperature and pressure-free assembly and bonding properties of TPE material offer a pertinent solution for simple and efficient loading and storage of reagents and other on-board components. This feature was demonstrated through integration and conditioning of microbeads, magnetic discs, dried DNA buffer reagents and spotted DNA array inserts. Furthermore, all microfluidic functions and plastic parts were designed according to the current injection mold-making knowledge for industrialization purposes. Therefore, the current work highlights a seamless strategy that promotes a feasible path for the transfer from prototype toward realistic industrialization. This work aims to establish the full potential for TPE-based centrifugal system as a mainstream microfluidic diagnostic platform for clinical diagnosis, water and food safety, and other molecular diagnostic applications.

Integrated air stream micromixer for performing bioanalytical assays on a plastic chip

This paper describes the design, functioning and use of an integrated mixer that relies on air flux to agitate microliter entities of fluid in an embedded microfluidic cavity. The system was fabricated from multiple layers of a thermoplastic elastomer and features circuits for both liquid and air supply along with pneumatic valves for process control. Internally-dyed polymer particles have been used to visualize flow within the fluid phase during agitation. Numerical modelling of the micromixer revealed an overall efficacy of 10(-1) to 10(-2) for momentum transfer at the air-water interface. Simulation of air vortex dynamics showed dependency of the flow pattern on the velocity of the flux entering the cavity. Three bioanalytical assays have been performed as proof-of-concept demonstrations. In a first assay, cells of Listeria monocytogenes were combined with magnetic nanoparticles (NPs), resulting in high-density coverage of the bacteria's surface with NPs after 1 min of agitation. This finding is contrasted by a control experiment without agitation for which interaction between bacteria and NPs remains low. In a second one, capture and release of genomic DNA from fungi through adsorption onto magnetic beads was tested and shown to be improved by agitation compared to non-agitated controls. A third assay finally involved fluorescently-labelled target oligonucleotide strands and polystyrene particles modified with DNA capture probes to perform detection of nucleic acids on beads. Excellent selectivity was obtained in a competitive hybridization process using a multiplexed micromixer chip design.

High throughput multilayer microfluidic particle separation platform using embedded thermoplastic-based micropumping

We present an integrated thermoplastic elastomer (TPE) based multilayer microfluidic device with an embedded peristaltic micropump and through-holes membrane for high throughput particle sorting and separation. Fluidic and pneumatic layers of the device were fabricated using hot-embossing lithography and commercially available polycarbonate membranes were succcessfully sandwiched between two thermoplastic elastomer fluidic layers integrated to a peristaltic micropumping layer. The integrated peristaltic micropump induces turbulence at the top-microfluidic layer ring which successfully avoids particle aggregation and membrane blocking even at nanorange size. We present herein the general design of the device structure and pumping characteristics for three devices with membrane pore sizes of 10 μm, 5 μm and 800 nm. By using this design we have successfully demonstrated a separation efficiency as high as 99% of polystyrene microbeads with different sizes and most importantly the separation of 390 nm particles from 2 μm beads was achieved. Using this device, we were also able to separate red blood cells with size of about 6-8 μm from osteoblasts typically larger than 10 μm to demonstrate the potential applicability of this platform for biological samples. The produced microfluidic chip operating at flow rates up to 100 μl min(-1) allows us to achieve efficient high-throughput sorting and separation of target particles/cells.

Thermo-active elastomer composite for optical heating in microfluidic systems

Single-walled carbon nanotubes are used as doping agents to form thermo-active composites with an elastomeric block-copolymer. Thermal imaging reveals that the temperature response upon irradiation with NIR laser light is dependent (among other things) on the mass fraction of the nanotubes in the polymer matrix.

All-thermoplastic nanoplasmonic microfluidic device for transmission SPR biosensing

Early and accurate disease diagnosis still remains a major challenge in clinical settings. Biomarkers could potentially provide useful tools for the detection and monitoring of disease progression, treatment safety and efficacy. Recent years have witnessed prodigious advancement in biosensor development with research directed towards rapid, real-time, label-free and sensitive biomarker detection. Among emerging techniques, nanoplasmonic biosensors pose tremendous potential to accelerate clinical diagnosis with real-time multiplexed analysis, rapid and miniaturized assays, low sample consumption and high sensitivity. In order to translate these technologies from the proof-of-principle concept level to point of care clinical diagnosis, integrated, portable devices having small footprint cartridges that house low-cost disposable consumables are sought. Towards this goal, we developed an all-polymeric nanoplasmonic microfluidic (NMF) transmission surface plasmon resonance (SPR) biosensor. The device was fabricated in thermoplastics using a simple, single step and cost-effective hot embossing technique amenable to mass production. The novel 3D hierarchical mold fabrication process enabled monolithic integration of blazed nanogratings within the detection chambers of a multichannel microfluidic system. Consequently, a single hard thermoplastic bottom substrate comprising plasmonic and fluidic features allowed integration of active fluidic elements, such as pneumatic valves, in the top soft thermoplastic cover, increasing device functionality. A simple and compact transmission-based optical setup was employed with multiplexed end-point or dual-channel kinetic detection capability which did not require stringent angular accuracy. The sensitivity, specificity and reproducibility of the transmission SPR biosensor was demonstrated through label-free immunodetection of soluble cell-surface glycoprotein sCD44 at clinically relevant picomolar to nanomolar concentrations.

Microfluidic designs and techniques using lab-on-a-chip devices for pathogen detection for point-of-care diagnostics

Effective pathogen detection is an essential prerequisite for the prevention and treatment of infectious diseases. Despite recent advances in biosensors, infectious diseases remain a major cause of illnesses and mortality throughout the world. For instance in developing countries, infectious diseases account for over half of the mortality rate. Pathogen detection platforms provide a fundamental tool in different fields including clinical diagnostics, pathology, drug discovery, clinical research, disease outbreaks, and food safety. Microfluidic lab-on-a-chip (LOC) devices offer many advantages for pathogen detection such as miniaturization, small sample volume, portability, rapid detection time and point-of-care diagnosis. This review paper outlines recent microfluidic based devices and LOC design strategies for pathogen detection with the main focus on the integration of different techniques that led to the development of sample-to-result devices. Several examples of recently developed devices are presented along with respective advantages and limitations of each design. Progresses made in biomarkers, sample preparation, amplification and fluid handling techniques using microfluidic platforms are also covered and strategies for multiplexing and high-throughput analysis, as well as point-of-care diagnosis, are discussed.

Nitric oxide delivery by core/shell superparamagnetic nanoparticle vehicles with enhanced biocompatibility

We report the synthesis of Fe(3)O(4)/silica core/shell nanoparticles and their functionalization with S-nitrosothiols. These nanoparticles are of immense interest because of their nitric oxide (NO) release capabilities in human alveolar epithelial cells. Moreover, they act as large storage reservoirs of NO that can be targeted magnetically to the specific site with a sustainable release of NO for up to 50 h. Such nanoparticles provide an enhancement of the biocompatibility with released NO while allowing intracellular accumulation ascribed to their small size.

In vitro biocompatibility assessment of functionalized magnetite nanoparticles: biological and cytotoxicological effects

In the biomedical field, nanomaterials have the potential for use in the targeted delivery of drugs in the human body and in the diagnosis and therapy of certain diseases. In the category of targeted delivery, magnetite (Fe(3)O(4)) nanoparticles have received much attention. As with any similar new therapy, when such nanoparticles are functionalized with chemical groups designed to permit the specific attachment of drugs, cytotoxicological testing is necessary before moving to animal models. Here, we consider several variously functionalized magnetite nanoparticles, including those prepared with (1) a monolayer of oleic acid (Fe(3)O(4)@OA), which is subsequently converted to (2) a shell of amine-containing silane (Fe(3)O(4)@NH(2)), (3) a shell of silica (Fe(3)O(4)@SiO(2)), and (4) a shell of amine-containing silane over a shell of silica (Fe(3)O(4)@SiO(2)@NH(2)). These latter three functionalities were evaluated for biocompatibility, cellular morphology, mitochondrial function (MTT assay), lactate dehydrogenase membrane leakage (LDH assay), and proinflammatory potential through enzyme linked immunosorbent assay (ELISA) for interleukin 6 (IL-6). Controlled tests were performed over a period of 72 h, with results showing LDH leakage and abnormal Il-6 secretion at high concentrations (>50 μg/mL). The tests showed that, in addition to the surface characteristics of the nanoparticles, both the nutrient medium and the time of suspension before exposure to cells also contribute to nanoparticle cytotoxicity.

[Management of severe accidental hypothermia]

Accidental hypothermia is an environmental condition with basic principles of classification and resuscitation that apply to mountain, sea or urban scenarios. Along with coagulopathy and acidosis, hypothermia belongs to the lethal triad of trauma victims requiring critical care. A customized healthcare chain is involved in its management, extending from on site assistance to intensive care, cardiac surgery and/or the extracorporeal circulation protocols. A good classification of the degree of hypothermia preceding admission contributes to improve management and avoids inappropriate referrals between hospitals. The most important issue is to admit hypothermia victims in asystolia or ventricular fibrillation to those hospitals equipped with the medical technology which these special clinical scenarios require. This study attempts to establish the foundations for optimum management of accidental hypothermia from first emergency care on site to treatment in hospital including, resuscitation and rewarming with extracorporeal circulation.

Use of a dual-labelled oligonucleotide as a DNA dosemeter for radiological exposure detection

A reporter molecule consisting of a synthetic oligonucleotide is being characterised for a novel damage detection scenario for its potential use as a field-deployable, personal deoxyribonucleic acid (DNA) dosemeter for radiation detection. This dosemeter is devoid of any biological properties other than being naked DNA and therefore has no DNA repair capabilities. It supports biodosimetry techniques, which require lengthy analysis of cells from irradiated individuals, and improves upon inorganic dosimetry, thereby providing for a more relevant means of measuring the accumulated dose from a potentially mixed-radiation field. Radiation-induced single strand breaks (SSBs) within the DNA result in a quantifiable fluorescent signal. Proof of concept has been achieved over 250 mGy-10 Gy dose range in radiation fields from ⁶⁰Co, with similar results seen using a linear accelerator X-ray source. Further refinements to both the molecule and the exposure/detection platform are expected to lead to enhanced levels of detection for mixed-field radiological events.

3D thermoplastic elastomer microfluidic devices for biological probe immobilization

Microfluidics has emerged as a valuable tool for the high-resolution patterning of biological probes on solid supports. Yet, its widespread adoption as a universal biological immobilization tool is still limited by several technical challenges, particularly for the patterning of isolated spots using three-dimensional (3D) channel networks. A key limitation arises from the difficulties to adapt the techniques and materials typically used in prototyping to low-cost mass-production. In this paper, we present the fabrication of thin thermoplastic elastomer membranes with microscopic through-holes using a hot-embossing process that is compatible with high-throughput manufacturing. The membranes provide the basis for the fabrication of highly integrated 3D microfluidic devices with a footprint of only 1 × 1 cm(2). When placed on a solid support, the device allows for the immobilization of up to 96 different probes in the form of a 10 × 10 array comprising isolated spots of 50 × 50 μm(2). The design of the channel network is optimized using 3D simulations based on the Lattice-Boltzmann method to promote capillary action as the sole force distributing the liquid in the device. Finally, we demonstrate the patterning of DNA and protein arrays on hard thermoplastic substrates yielding spots of excellent definition that prove to be highly specific in subsequent hybridization experiments.