Microcapillary Film Research Articles

Dilution Reduces Sample Matrix Effects for Rapid, Direct, and Miniaturised Phenotypic Antibiotic Susceptibility Tests for Bovine Mastitis.

The time-consuming nature of current methods for detecting antimicrobial resistance (AMR) to guide mastitis treatment and for surveillance, drives innovation towards faster, easier, and more portable technology. Rapid on-farm testing could guide antibiotic selection, reducing misuse that contributes to resistance. We identify challenges that arise when developing miniaturized antibiotic susceptibility tests (AST) for rapid on-farm use directly in milk. We experimentally studied three factors: sample matrix (specifically milk or spoiled milk); the commensal bacteria found in fresh bovine milk; and result time on the performance of miniaturised AST. Microfluidic "dip-and-test" devices made from microcapillary film (MCF) were able to monitor Gram-negative bacterial growth colourimetrically even in the presence of milk and yoghurt (used to simulate spoiled milk samples), as long as this sample matrix was diluted 1:5 or more in growth medium. Growth detection kinetics using resazurin was not changed by milk at final concentrations of 20% or lower, but a significant delay was seen with yoghurt above 10%. The minimum inhibitory concentration (MIC) for ciprofloxacin and gentamicin was increased in the presence of higher concentrations of milk and yoghurt. When diluted to 1% all observed MIC were within range, indicating dilution may be sufficient to avoid milk matrix interfering with microfluidic AST. We found a median commensal cell count of 6 × 105 CFU/mL across 40 healthy milk samples and tested if these bacteria could alter microfluidic AST. We found that false susceptibility may be observed at early endpoint times if testing some pathogen and commensal mixtures. However, such errors are only expected to occur when a susceptible commensal organism is present at higher cell density relative to the resistant pathogen, and this can be avoided by reading at later endpoints, leading to a trade-off between accuracy and time-to-result. We conclude that with further optimisation, and additional studies of Gram-positive organisms, it should be possible to obtain rapid results for microfluidic AST, but a trade-off is needed between time-to-result, sample dilution, and accuracy.

Continuous flow of reagents interferes with the kinetics and equilibrium of antibody-antigen binding in microfluidic heterogeneous immunoassays

Though fundamentally important for the design and development of quantitative point-of-care diagnostics devices, the effect of fluid flow in heterogeneous immunoassays remains unclear. We present the first experimental study using actual microfluidic strips showing both kinetics and equilibrium of antibody-analyte binding are dependent on flow rate, Q of reagents/sample. We have passively adsorbed an antibody in the inner surface of 212 ± 12 µm, 10-bore microcapillary film and pumped continuously a second (antigen) molecule in the range Q = 10–1000 µL/min. Sections of the film with 40 mm in length were then sacrificed over time enabling ELISA quantitation of the extent of antibody-antigen binding on each strip; other microfluidic technologies would require sacrificing the whole device, making it laborious and expensive. Absorbance data fitted to a kinetic model enabled determining Kon, Koff and affinity constant Keq = Kon/Koff, confirming the impact of Q. With limiting antigen, a 4-fold reduction in Kon and 3-fold in Keq was observed by shifting antigen incubation from stagnant to continuous Q = 10 µL/min. Flow caused up to 2-fold increment in the limit of detection (LoD) and assay time, suggesting a direct physical interference of fluid flow on the molecular binding and non-specific (background) binding, presumably through the effect of shear flow, which could include re-orientation of biomolecules. Although the biophysics behind such flow effect is yet to be understood, this work will help speeding up the development of protocols for development and implementation of microfluidic immunoassay technology for high-performance point-of-care (POC) testing.

Smartphone multiplex microcapillary diagnostics using Cygnus: Development andevaluation of rapid serotype-specific NS1 detection with dengue patient samples.

Laboratory diagnosis of dengue virus (DENV) infection including DENV serotyping requires skilled labor and well-equipped settings. DENV NS1 lateral flow rapid test (LFT) provides simplicity but lacks ability to identify serotype. A simple, economical, point-of-care device for serotyping is still needed. We present a gravity driven, smartphone compatible, microfluidic device using microcapillary film (MCF) to perform multiplex serotype-specific immunoassay detection of dengue virus NS1. A novel device–termed Cygnus–with a stackable design allows analysis of 1 to 12 samples in parallel in 40 minutes. A sandwich enzyme immunoassay was developed to specifically detect NS1 of all four DENV serotypes in one 60-μl plasma sample. This test aims to bridge the gap between rapid LFT and laboratory microplate ELISAs in terms of sensitivity, usability, accessibility and speed. The Cygnus NS1 assay was evaluated with retrospective undiluted plasma samples from 205 DENV infected patients alongside 50 febrile illness negative controls. Against the gold standard RT-PCR, clinical sensitivity for Cygnus was 82% in overall (with 78, 78, 80 and 76% for DENV1-4, respectively), comparable to an in-house serotyping NS1 microplate ELISA (82% vs 83%) but superior to commercial NS1-LFT (82% vs 74%). Specificity of the Cygnus device was 86%, lower than that of NS1-microplate ELISA and NS1-LFT (100% and 98%, respectively). For Cygnus positive samples, identification of DENV serotypes DENV2-4 matched those by RT-PCR by 100%, but for DENV1 capillaries false positives were seen, suggesting an improved DENV1 capture antibody is needed to increase specificity. Overall performance of Cygnus showed substantial agreement to NS1-microplate ELISA (κ = 0.68, 95%CI 0.58–0.77) and NS1-LFT (κ = 0.71, 95%CI 0.63–0.80). Although further refinement for DENV-1 NS1 detection is needed, the advantages of multiplexing and rapid processing time, this Cygnus device could deliver point-of-care NS1 antigen testing including serotyping for timely DENV diagnosis for epidemic surveillance and outbreak prediction.

Gravity-Driven Microfluidic Siphons: Fluidic Characterization and Application to Quantitative Immunoassays.

A range of biosensing techniques including immunoassays are routinely used for quantitation of analytes in biological samples and available in a range of formats, from centralized lab testing (e.g., microplate enzyme-linked immunosorbent assay (ELISA)) to automated point-of-care (POC) and lateral flow immunochromatographic tests. High analytical performance is intrinsically linked to the use of a sequence of reagent and washing steps, yet this is extremely challenging to deliver at the POC without a high level of fluidic control involving, e.g., automation, fluidic pumping, or manual fluid handling/pipetting. Here we introduce a microfluidic siphon concept that conceptualizes a multistep ″dipstick″ for quantitative, enzymatically amplified immunoassays using a strip of microporous or microbored material. We demonstrated that gravity-driven siphon flow can be realized in single-bore glass capillaries, a multibored microcapillary film, and a glass fiber porous membrane. In contrast to other POC devices proposed to date, the operation of the siphon is only dependent on the hydrostatic liquid pressure (gravity) and not capillary forces, and the unique stepwise approach to the delivery of the sample and immunoassay reagents results in zero dead volume in the device, no reagent overlap or carryover, and full start/stop fluid control. We demonstrated applications of a 10-bore microfluidic siphon as a portable ELISA system without compromised quantitative capabilities in two global diagnostic applications: (1) a four-plex sandwich ELISA for rapid smartphone dengue serotype identification by serotype-specific dengue virus NS1 antigen detection, relevant for acute dengue fever diagnosis, and (2) quantitation of anti-SARS-CoV-2 IgG and IgM titers in spiked serum samples. Diagnostic siphons provide the opportunity for high-performance immunoassay testing outside sophisticated laboratories, meeting the rapidly changing global clinical and public health needs.

Selective photocatalytic synthesis of benzaldehyde in microcapillaries with immobilized carbon nitride

Photocatalysis on microfluidic reactors can be an environmental-friendly strategy to conventional chemical synthesis methods to find selective and efficient processes to produce high value-added molecules.In this work, we report for the first time a fluoropolymer microcapillary system with an immobilizedmetal-free thermal modified carbon nitride (GCN-T)catalyst. This strategy enabled a user-friendly, plug-and-plug selective chemistry using an external UV light (λ = 392 nm) and aqueous solutions. To intensify the Benzaldehyde (BAL) production, we explored the microfluidic photocatalytic conversion of Benzyl alcohol (BA). We obtained 0.20 mM of BAL using immobilized GCN-T after 2.4 min of residence time. The results were benchmarked against the same reactor using suspended catalysts and against a conventional batch reactor. Immobilized GCN performed similarly to suspended GCN in the microfluidic reactor (0.18 mM of BAL). We increase BAL yield by 9-fold after 2.4 min using suspended GCN in a microfluidic reactor comparing to a batch reactor. The stability of immobilized photocatalyst was confirmed in reuse studies where 0.20 and 0.17 mM of BAL were produced after one and four utilization runs, respectively. We anticipate this can be related to the presence of a high concentration of particles closer to the microreactor’s inner wall, allowing the effective activation of GCN particles with UV irradiation. The immobilization of the catalyst avoided its blockage in the microfluidic channels and enabled the reuse without any further separation. To the best of our knowledge, this is the first report using the microcapillary film reactor and immobilized carbon nitride for the selective photocatalytic synthesis of BAL.

Fast prototyping using 3D printed templates and flexible fluoropolymer microcapillary films offers enhanced micromixing in immobilised (bio)catalytic reactions

Microreactors offer large surface-area-to-volume (SAV) ratios and short diffusion distances, yet, even at sub-millimetre space, there remains a level of mass transfer control of reactions. This can be minimised using passive micromixers currently requiring access to advanced microfabrication techniques. We report the fast fabrication and in-depth micromixing characterisation of inexpensive non-linear microstructure prototypes using, for the first time, a flexible fluoropolymer microcapillary film (MCF) re-shaped, post-extrusion, with 3D printed templates offering in-flow enhancement of mass transfer in immobilised (bio)catalytic reactions not previously studied for this type of micro-engineered material. The versatile “push-and-click” 3D printed templates allow one-step production of multi-bored, non-invasive micromixers with simple architectures, namely ‘square’, ‘zigzag’ and ‘wavy’ geometries without the limitations of conventional microfluidic devices. The passive micromixers were numerically evaluated using Computational Fluid Dynamics (CFDs) and extensively validated experimentally using novel Residence time distribution (RTD) data which assessed the role of Reynold numbers (0.6 – 60) and molecular diffusion coefficients (10−6 –10−11 m2/s), providing significant in-depth understanding of fluid flow distribution. By evaluating the in-flow oxidative coupling reaction of o-phenylenediamine (OPD, a chromogenic substrate) to 2,3-diaminophenazine (DAP) with an immobilised enzyme, horseradish peroxidase (HRP), we demonstrated the reaction rates in the ‘square’ and ‘zigzag’ (sharp bends) were improved by ∼43 and ∼46% respectively, compared to straight microcapillaries. This is linked to enhanced radial fluid movement. The proposed prototypes can be readily tailored for facilitated fabrication of practical high-performance microreactors suited for heterogeneous assays or in-flow (bio)catalytic reactions in non-microdevice dedicated labs.

CFD modeling of pharmaceuticals and CECs removal by UV/H2O2 process in helical microcapillary photoreactors and evaluation of OH radical rate constants

Process intensification by tailored secondary flow in helical microcapillary film (MCF) photoreactors was unveiled by computational fluid dynamics, and it was revealed for the removal of six common contaminants of emerging concern CECs (the antiviral Acyclovir, the antiretrovirals Stavudine and Zidovudine, and the biocidal antifungal agents Methylisothiazolinone, Benzisothiazolinone and Isoxazole) in water by UV hydrogen peroxide. The MCF photoreactors consisted of fluoropolymer films containing 10 microchannels with diameter varying from 100 to 1000 µm coiled around a UVC lamp. In contrast to a MCF with straight channels, mixing intensification by secondary flow (Dean vortices) caused by the helical shape of the microcapillary strongly enhanced the radial fluid mixing, further supplementing the transport of the reacting species by Taylor-Aris dispersion. The intensity of the Dean vortices formed was correlated to the Dean (De) and Schmidt (Sc) numbers through a new correlation for the radial Peclet, which established that these become significant when De1.94Sc>67. Thus, the second-order reaction rate constant of the six CECs with OH• radicals (kOH) determined in a helical MCF photoreactor increased (4.4% up to 37.9%) in comparison to those determined assuming a MCF photoreactor with plug flow. In addition, the helical shape of the MCF significantly diminished mass transfer limitations and decreased the CECs Electrical Energy per Order Reduction (EEO), paving the way for scaling-up of helical microcapillary photoreactor technology. This study shows how micromixing can be successfully exploited to design more efficient microcapillary photoreactors.

Microcapillary film reactor outperforms single-bore mesocapillary reactors in continuous flow chemical reactions

Meso- and micro-flow reactors are routinely used in continuous flow chemistry, however the role of capillary diameter, D, on conversion and reaction rates is often overlooked during scale-up. Volume, pressured drop and diffusion distances/times must be delicately balanced to fully realize the hydrodynamic capabilities of continuous chemical flow reactors. We carried out a comprehensive Computational Fluid Dynamics analysis experimentally validated with detailed fluid tracing, residence time distributions and continuous chemical reactions (neutralization and 4th Bourne reaction) to fully elucidate the role of D and molecular diffusion in reagents dispersion and chemical conversion. To our understanding, we captured and reported both numerically and experimentally for the first time the transition from convective, segregated flow to plug flow and dispersed flow, which we propose is linked to a dimensionless ratio between the time scales of diffusion to convection, tdiff/tconv. We tested three tubular systems: a small-bore (i.d. ~1100 µm) and large-bore (i.d. ~2400 µm) capillary reactor and a novel multiplexed (10-bore) Microcapillary Film Reactor (MFR) with mean i.d. 363 ± 32.2 µm. In the MFR’s narrow microcapillaries we observed excellent radial diffusion linked to the small diffusion distance, with low dimensionless axial dispersion coefficient values (Dax/uL) ranging from 0.0015 ± 0.0005 to 0.0033 ± 0.0006 (for flow rates 0.5–5.0 mL/min), exhibiting all the desired features of a high-performance ‘plug’ flow system. Dax/uL remained mostly independent of the Reynolds number, whereas for the single, large bore capillary the Dax/uL values (0.032–0.057) increased linearly with the Reynolds numbers (19.4–48.5), shifting towards very dispersive flow. We propose splitting flow through multiple parallel microcapillaries as in the MFR is a superior strategy for scaling-up continuous flow reactions compared to increasing D, which neglects diffusive effects.

Study on Co-flow Effect on Janus Droplet Generation Based on Step Emulsification

Abstract Continuous phase co-flow can increase the throughput and control the flexibility of step emulsification, and has an important effect on droplet microfluidic. In this study, a multi-channel step emulsification device was developed to generate Janus droplets and to study the effects of both continuous phase co-flow and dispersed phase flow on the generation of Janus droplets. Janus droplets were successfully prepared by the device, and the generation stability was optimized by using glass capillaries instead of microcapillary film based on their different wall contact angles at the channel outlet. The results showed that when the continuous phase co-flow rate increased, the resulted Janus droplet diameter decreased, and the generation frequency increased. When the flow rate of dispersed phase increased, both the diameter and generation frequency of the generated Janus droplets increased. Within the scope of this study, the diameter and the generation frequency of the Janus droplets could be controlled to be 638–1640 μm and 0.02–2.2 Hz, respectively. In addition, three-component droplets were generated successfully and steadily by a chip which was prepared based on the two-component droplet generation device. By changing the flow rates of two phases, the droplet diameter and frequency could also been tuned on-line. It was found that the co-flow effect had a greater impact on the generation of three-component droplets because of the result that the three-component droplet diameter changed greater than the two-component Janus droplet when changing both the continuous and dispersed phase flows. The results of this study provided a basis and method for micro and trace research of chemical and analysis industry.

Development of a disposable micro-capillary film grafted with peptide ligands for immunoadsorption

Traditional chromatographic techniques used in downstream processes of biomolecule manufacturing are often time-consuming and expensive. In this study, a cost-effective microporous micro-capillary film (MMCF) composed of ethylenevinyl alcohol (EVOH) was evaluated for its potential application in immunoadsorption with high process efficiency. A peptide ligand Ac-Phe-Tyr-His-Glu (Ac-FYHE) was immobilized on the inner surface of MMCF for selective binding of human immunoglobulin (hIgG). The porous structure and chemical properties of the prepared MMCF were confirmed by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). hIgG (2 mg/ml) adsorption studies demonstrated that the binding process followed a Langmuir isotherm with equilibrium adsorption capacities of 9.31 and 3.47 mg/ml adsorbent under static and dynamic conditions, respectively. Moreover, the membrane showed good flowrate tolerance when studied under flowrates of 0.5 ml/min to 10 ml/min. hIgG purity was 88.2% when obtained from an hIgG (2 mg/ml) and HSA (8 mg/ml) mixture and the purity remained over 80.0% when hIgG concentrations increased in the mixtures. Moreover, purity of 82.3% was achieved when removing hIgG directly from human serum. The MMCF-Ac-FYHE affinity column is expected to selectively remove hIgG from blood for the treatment of autoimmune diseases with high efficiency and cost effectiveness.

Immunocapture of Escherichia coli in a fluoropolymer microcapillary array

This study presents novel experimental insights into the direct quantitation and immunocapture of bacteria cells in a fluoropolymer microcapillary array, using Escherichia coli as work model, a pathogen responsible for around 80% of urinary tract infections (UTIs). In spite of the current clinical demand for sensitive tests for rapid identification and quantitation of pathogens in human samples, portable diagnostic tests developed to date lack the specificity, limit of detection and speed for effective implementation in bacteria detection at point-of-care. The ‘open microfluidic’ approach presented in this work directly addresses those challenges. We report for the first time evidence of immunocapture of bacteria using polyclonal antibodies immobilized on the inner surface of an inexpensive 10-bore, 200 μm internal diameter FEP-Teflon® MicroCapillary Film, with a limit of detection (LoD) of at just 1 colony forming unit (CFU). In capillaries coated with less than a full monolayer of capture antibody, we observed a first order equilibrium, with bacteria captured (in CFUs/ml) linearly proportional to the CFU/ml in the incubated sample. We captured up to 100% of E. coli cells, with clear evidence of immunospecificity as demonstrated by testing with a different bacteria specie (in this case Bacillus subtillis). We noticed gravity settling of bacteria within the capillaries created a gradient of concentration which on the overall enhanced the capturing of cells up to 6 orders of magnitude beyond the theoretic full monolayer (∼4.5 × 104 CFUs/ml), with washings having an unnoticeable effect. Our data particularly highlights quantitatively the relevance of interrogation volume in respect to the miniaturisation of bacteria quantitation, which cannot be solved with the most sophisticated imaging equipment. A further set of continuous flow experiments at a flow rate of just ∼1 μl/min (corresponding to a wall shear rate of ∼101 s−1 and superficial flow velocity ∼53 μm/s) showed a degree of flow focusing, yet the mobility, antibody affinity capturing and gravity settling of bacteria cells enabled successful capturing in the microcapillaries. These results will inform the future development of effective microfluidic approaches for rapid point-of-care quantitation of bacterial pathogens and in particular rule-in of E. coli in UTIs.

Removal of antiretroviral drugs stavudine and zidovudine in water under UV254 and UV254/H2O2 processes: Quantum yields, kinetics and ecotoxicology assessment

The concentration of antiretroviral drugs in wastewater treatment plants (WWTP) effluents and surface waters of many countries has increased significantly due to their widespread use for HIV treatment. In this study, the removal of stavudine and zidovudine under UV254 photolysis or UV254/H2O2 was investigated in a microcapillary film (MCF) photoreactor, using minimal water samples quantities. The UV254 quantum yield of zidovudine, (2.357 ± 0.0589)·10−2 mol ein−1 (pH 4.0–8.0), was 28-fold higher that the yield of stavudine (8.34 ± 0.334)·10−4 mol ein−1 (pH 6.0–8.0). The second-order rate constant kOH,iof reaction of hydroxyl radical with the antiretrovirals (UV254/H2O2 process) were determined by kinetics modeling: (9.98 ± 0.68)·108 M−1 s−1 (pH 4.0–8.0) for zidovudine and (2.03 ± 0.18)·109 M−1 s−1 (pH 6.0–8.0) for stavudine. A battery of ecotoxicological tests (i.e. inhibition growth, bioluminescence, mutagenic and genotoxic activity) using bacteria (Aliivibrio fischeri, Salmonella typhimurium), crustacean (Daphnia magna) and algae (Raphidocelis subcapitata) revealed a marked influence of the UV dose on the ecotoxicological activity. The UV254/H2O2 treatment process reduced the ecotoxicological risk associated to direct photolysis of the antiretrovirals aqueous solutions, but required significantly higher UV254 doses (≥2000 mJ cm−2) in comparison to common water UV disinfection processes.

A high-throughput multi-microfluidic crystal generator (MMicroCryGen) platform for facile screening of polymorphism and crystal morphology for pharmaceutical compounds.

In this work, a novel multi-microfluidic crystallization platform called MMicroCryGen is presented, offering a facile methodology for generating individual crystals for fast and easy screening of the polymorphism and crystal habit of solid compounds. The MMicroCryGen device is capable of performing 8 × 10 cooling crystallization experiments in parallel using 8 disposable microcapillary film strips, each requiring less than 25 μL of solution. Compared to traditional microfluidic systems, the MMicroCryGen platform does not require complex fluid handling; it can be directly integrated with a 96-well microplate and it can also work in a "dipstick" mode. The produced crystals can be safely and directly observed inside the capillaries by optical and spectroscopic techniques. The platform was validated by performing a number of independent experimental runs for: (1) polymorph and hydrate screening of ortho-aminobenzoic acid, succinic acid and piroxicam; (2) co-crystal form screening of the p-toluenesulfonamide/triphenylphosphine oxide system; (3) studying the effect of o-toluic acid on ortho-aminobenzoic cooling crystallization (effect of structurally related additives). In all three cases, all known solid forms were identified with a single experiment using ∼200 μL of solvent and just a few micrograms of the solid material. The MMicroCryGen is simple to use, inexpensive and it provides increased flexibility compared to traditional crystallization techniques, being an effective new microfluidic solution for solid form screening in pharmaceutical, fine chemicals, food and agrochemical industries.

Photodegradation and ecotoxicology of acyclovir in water under UV254 and UV254/H2O2 processes

The photochemical and ecotoxicological fate of acyclovir (ACY) through UV254 direct photolysis and in the presence of hydroxyl radicals (UV254/H2O2 process) were investigated in a microcapillary film (MCF) array photoreactor, which provided ultrarapid and accurate photochemical reaction kinetics. The UVC phototransformation of ACY was found to be unaffected by pH in the range from 4.5 to 8.0 and resembled an apparent autocatalytic reaction. The proposed mechanism included the formation of a photochemical intermediate (ϕACY = (1.62 ± 0.07)·10−3 mol ein−1) that further reacted with ACY to form by-products (k’ = (5.64 ± 0.03)·10−3 M−1 s−1). The photolysis of ACY in the presence of hydrogen peroxide accelerated the removal of ACY as a result of formation of hydroxyl radicals. The kinetic constant for the reaction of OH radicals with ACY (kOH/ACY) determined with the kinetic modeling method was (1.23 ± 0.07)·109 M−1 s−1 and with the competition kinetics method was (2.30 ± 0.11)·109 M−1 s−1 with competition kinetics. The acute and chronic effects of the treated aqueous mixtures on different living organisms (Vibrio fischeri, Raphidocelis subcapitata, D. magna) revealed significantly lower toxicity for the samples treated with UV254/H2O2 in comparison to those collected during UV254 treatment. This result suggests that the addition of moderate quantity of hydrogen peroxide (30–150 mg L−1) might be a useful strategy to reduce the ecotoxicity of UV254 based sanitary engineered systems for water reclamation.

Towards One-Step Quantitation of Prostate-Specific Antigen (PSA) in Microfluidic Devices: Feasibility of Optical Detection with Nanoparticle Labels

Rapid and quantitative prostate-specific antigen (PSA) biomarker detection would be beneficial to cancer diagnostics, improving early detection and therefore increasing chances of survival. Nanoparticle-based detection is routinely used in one-step nitrocellulose-based lateral flow (LF) immunoassays; however, it is well established within the scientific diagnostic community that LF technology lacks sensitivity for measuring biomarkers, such as prostate-specific antigen (PSA). A trend in point-of-care (POC) protein biomarker quantitation is the miniaturization of immunoassays in microfluidic devices. This work aimed at testing the feasibility of carbon and gold nanoparticles as immunoassay labels for PSA detection with cost-effective optical detection in a novel microfluidic POC platform called microcapillary film (MCF), consisting of a parallel array of fluoropolymer microcapillaries with 200-μm internal diameter. With neutravidin-coated carbon, nanoparticles were able to quantify an immobilized biotinylated monoclonal antibody (coating solution from 10 to 40 μg/ml) and PSA was successfully quantified in a sandwich assay using silver-enhanced gold nanoparticles and a flatbed scanner; yet, the dynamic range was limited to 10–100 ng/ml. Although direct optical detection of PSA without enzymatic amplification or fluorophores is possible and technically appealing for the simplified fluidics and signal scanning setups involved, ultimately, the binding of a thin layer of nanoparticles onto the wall of transparent microcapillaries is not sufficient to cause a significant drop on the optical colorimetric signal. Future studies will explore the use of fluorescence nanoparticles.

Determination of hydrogen peroxide using novel test strips based on plastic microcapillary film

This work proposes a novel method for the semi-quantitative determination of hydrogen peroxide (H2O2) in routine and on-site applications.

The development of a weak anion micro-capillary film for protein chromatography

In this study, the surface of a microporous walled micro-capillary film (MMCF) was modified into a weak anion exchanger by coupling cyanuric chloride and 2-diethylaminoethylamine (DEAE) to the ethylene-vinyl alcohol (EVOH) matrix. Fourier transform infrared spectroscopy (FTIR) measurements of modified and unmodified MMCFs confirmed the addition of a triazine ring and DEAE onto the membrane. Binding of bovine serum albumin (BSA) at pH 7.2 was found to follow a Langmuir isotherm with a maximum equilibrium binding of 12.4mg BSA/mL adsorbent and 8.2mg BSA/mL adsorbent under static and flow conditions, respectively. The ion exchange capacity, determined by Mohr’s titration of chlorine atoms displaced from the functionalised surface, was found to be 195±21μmol Cl−/mL of adsorber, comparable to commercial ion exchangers. BSA adsorption onto the ion exchanger was strongly pH-dependant, with an observed reduction in binding above pH 8.2.Frontal experiments of a BSA (5mg/mL) and lysozyme (5mg/mL) mixture demonstrated successful separation of BSA from lysozyme at more than 97% purity as verified by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Separation between similarly charged anionic molecules was also achieved using BSA (5mg/mL) and herring sperm DNA (0.25mg/mL). BSA was extracted at 100% purity, demonstrating the ability of MMCF-DEAE to remove significant DNA contamination from a protein solution. These experiments highlight the potential for MMCFs to be used for fast protein purification in preparative chromatography application.

Novel prototyping method for microfluidic devices based on thermoplastic polyurethane microcapillary film

Thermoplastic polyurethane microcapillary film (TPU-MCF), as a novel extruded product, inherently contains an array of circular micron-sized capillaries embedded inside the polymer matrix. With the aid of simple laser cutting and conventional sealing technologies, a rapid prototyping method for microfluidic devices is proposed based on the ready-made microstructure of MCFs. Two functionalized microfluidic devices: serpentine micromixer and multi-droplet generator, are rapidly fabricated to demonstrate the advantages and potential of employing this new method. The whole proof-of-concept fabrication process can be completed in 8–10 min in a simple way; each procedure is repeatable with stable performance control of microfluidic devices; and the material cost can be as low as $0.01 for each device. The TPU-MCF and this novel method are expected to provide a new perspective and alternative in microfluidic community with particular requirements.

Removal of benzoylecgonine from water matrices through UV254/H2O2 process: Reaction kinetic modeling, ecotoxicity and genotoxicity assessment

Benzoylecgonine (BE), the main cocaine metabolite, has been detected in numerous surface water and treatment plants effluents in Europe and there is urgent need for effective treatment methods. In this study, the removal of BE by the UV254/H2O2 process from different water matrices was investigated. By means of competition kinetics method, the kinetic constant of reaction between BE and the photogenerated hydroxyl radicals (OH) was estimated resulting in kOH/BE=5.13×109M−1s−1. By-products and water matrices scavengers effects were estimated by numerical modeling of the reaction kinetics for the UV254/H2O2 process and validated in an innovative microcapillary film (MCF) array photoreactor and in a conventional batch photoreactor. The ecotoxicity of the water before and after treatment was evaluated with four organisms Raphidocelis subcapitata, Daphnia magna, Caenorhabditis elegans, and Vicia faba. The results provided evidence that BE and its transformation by-products do not have significant adverse effects on R. subcapitata, while D. magna underwent an increase of lipid droplets. C. elegans was the most sensitive to BE and its by-products. Furthermore, a genotoxicity assay, using V. faba, showed cytogenic damages during the cell mitosis of primary roots.

Designing an Artificial Golgi reactor to achieve targeted glycosylation of monoclonal antibodies

The therapeutic efficacy of monoclonal antibodies (mAbs) is dependent on their glycosylation patterns. As the largest group of currently approved biopharmaceuticals, the microheterogeneity in mAb oligosaccharide profiles deriving from mammalian cell production is a challenge to the biopharmaceutical industry. Disengaging the glycosylation process from the cell may offer significant enhancement of product quality and allow better control and reproducibility in line with the Quality‐by‐Design paradigm. Three potential designs of an Artificial Golgi reactor implementing targeted sequential glycosylation of mAbs are proposed including a (1) microcapillary film reactor, (2) packed bed reactor with nonporous pellets, and (3) packed bed reactor with porous pellets. Detailed mathematical models are developed to predict their performance for a range of design and operational parameters. While all three reactor designs can achieve desired conversion levels, the choice of a particular one depends on the required throughput and the associated cost of enzymes and co‐substrates. © 2016 The Authors AIChE Journal published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers AIChE J, 62: 2959–2973, 2016