Disposable Cartridge Research Articles

Miniaturized Biosensors to Preserve and Monitor Cultural Heritage: from Medical to Conservation Diagnosis.

The point-of-care testing concept has been exploited to design and develop portable and cheap bioanalytical systems that can be used on-site by conservators. These systems employ lateral flow immunoassays to simultaneously detect two proteins (ovalbumin and collagen) in artworks. For an in-depth study on the application of these portable biosensors, both chemiluminescent and colorimetric detections were developed and compared in terms of sensitivity and feasibility. The chemiluminescent system displayed the best analytical performance (that is, two orders of magnitude lower limits of detection than the colorimetric system). To simplify its use, a disposable cartridge was designed ad hoc for this specific application. These results highlight the enormous potential of these inexpensive, easy-to-use, and minimally invasive diagnostic tools for conservators in the cultural heritage field.

Miniaturized Biosensors to Preserve and Monitor Cultural Heritage: from Medical to Conservation Diagnosis

AbstractThe point‐of‐care testing concept has been exploited to design and develop portable and cheap bioanalytical systems that can be used on‐site by conservators. These systems employ lateral flow immunoassays to simultaneously detect two proteins (ovalbumin and collagen) in artworks. For an in‐depth study on the application of these portable biosensors, both chemiluminescent and colorimetric detections were developed and compared in terms of sensitivity and feasibility. The chemiluminescent system displayed the best analytical performance (that is, two orders of magnitude lower limits of detection than the colorimetric system). To simplify its use, a disposable cartridge was designed ad hoc for this specific application. These results highlight the enormous potential of these inexpensive, easy‐to‐use, and minimally invasive diagnostic tools for conservators in the cultural heritage field.

Electrochemical Peroxide Generation for in Situ Disinfection

Novel technologies with limited earth support are required to enable energy-efficient maintenance of closed air, water, and waste systems in microgravity spacecraft habitats such as International space station (ISS). One area of need for the interstellar travel community is cleaning/sanitizing supplies to meet personal hygiene requirements, which is currently accomplished through the use of pre-packaged, disposable, wetted wipes, or ion exchange cartridges. These items represent an appreciable carry-along mass and disposal/replacement burden requiring earth based support. Therefore, if a system could be developed to use onboard utilities to create cleaning and disinfecting solutions it would reduce the astronaut’s dependence on earth based supplies. We are addressing this challenge by demonstrating a technology that will use utilities on-board the spacecraft habitat to create sanitizing solutions and eliminate the need for regular delivery of disinfecting wipes. This concept is founded on the electrochemical reduction of oxygen to hydrogen peroxide using readily available on-board supplies of O2 and water. Peroxide is well-established disinfectant with non-toxic decomposition products (viz., O2 and H2O), that is safe enough for human contact to be sold commercially as a 3% w/w solution. Thus, it is an ideal disinfecting solution for closed space environments. The electrochemical reduction of oxygen to hydrogen peroxide occurs by two electron transfer reactions which proceeds as [O2 + 2H+ + 2e- → H2O2 or O2 + 2H2O + 2e- → H2O2 + 2OH-][1]. We designed and constructed an electrochemical reactor for generating peroxide that is compatible with the available low conductivity water stream based on a patented concept of one of our commercialization partners (De Nora Technology, Inc. U.S. patent number 6,254,762). The peroxide generation unit (PGU) system consists of oxygen chamber, catholyte chamber (with catalyzed GDE cathode[2]), whose volume can be modified as desired by changing the catholyte plate (width/length) and size/density of the NAFION bead packing material, and anolyte chamber with commercially-available mixed-metal oxide anode pressed against a cation exchange membrane, as shown in the conceptual schematic (Figure - left) and the modified PGU (Figure - right). Initial trials confirmed that the PGU can generate peroxide utilizing high conductivity sodium sulfate as catholyte. Further, the PGU was used to demonstrate the potential of generating peroxide in very low conductivity electrolytes such as distilled water (DI) and reverse osmosis water (RO) by enabling transfer conductivity through the use of NAFION ionomer “beads”. These results are promising and an early indication that the PGU will be able to generate peroxide with high performance efficiency. Faraday is continuing the technology development efforts by: (1) demonstrating the potential of the device design by testing under zero gravity; (2) optimizing the gas diffusion electrode (GDE) catalytic structure, and wettability, (3) demonstrating the potential to use onboard International Space Station (ISS) water utilities, (4) developing an electrochemical peroxide detector, and (5) designing and building an α-scale reactor to produce 1 L/day of 2 w/w% H2O2. Some of the results aimed at evaluating the system in zero-gravity environments will be presented at the conference. In addition to being an integral component of long term life support on NASA manned space missions; this technology has the potential to be an alternative method for synthesis of commercial hydrogen peroxide for on-demand onsite disinfection of process waste streams and/or field remediation systems. Acknowledgements: The financial support of NASA Contract No. NNX16CA43P and NNX17CJ12C is acknowledged. We would also like to thank Dr. Jeffrey J. Sweterlitsch from NASA Johnson Space Center (Houston, TX), who provided insight and expertise that greatly assisted the research

An evaluation of electronic cigarette formulations and aerosols for harmful and potentially harmful constituents (HPHCs) typically derived from combustion

U.S. FDA draft guidance recommends reporting quantities of designated harmful and potentially harmful constituents (HPHCs) in e-cigarette e-liquids and aerosols. The HPHC list comprises potential matrix-related compounds, flavors, nicotine, tobacco-related impurities, leachables, thermal degradation products, and combustion-related compounds. E-cigarettes contain trace levels of many of these constituents due to tobacco-derived nicotine and thermal degradation. However, combustion-related HPHCs are not likely to be found due to the relatively low operating temperatures of most e-cigarettes. The purpose of this work was to use highly sensitive, selective, and validated analytical methods to determine if these combustion-related HPHCs (three aromatic amines, five volatile organic compounds, and the polycyclic aromatic hydrocarbon benzo[a]pyrene) are detectable in commercial refill e-liquids, reference e-cigarette e-liquids, and aerosols generated from rechargeable e-cigarettes with disposable cartridges (often referred to as “cig-a-likes”). In addition, the transfer efficiency of these constituents from e-liquid to aerosol was evaluated when these HPHCs were added to the e-liquids prior to aerosol formation. This work demonstrates that combustion-related HPHCs are not present at measurable levels in the commercial and reference e-liquids or e-cigarette aerosols tested. Additionally, when combustion-related HPHCs are added to the e-liquids, they transfer to the aerosol with transfer efficiencies ranging from 49% to 99%.

In house validation of a high resolution mass spectrometry Orbitrap-based method for multiple allergen detection in a processed model food.

In recent years, mass spectrometry (MS) has been establishing its role in the development of analytical methods for multiple allergen detection, but most analyses are being carried out on low-resolution mass spectrometers such as triple quadrupole or ion traps. In this investigation, performance provided by a high resolution (HR) hybrid quadrupole-Orbitrap™ MS platform for the multiple allergens detection in processed food matrix is presented. In particular, three different acquisition modes were compared: full-MS, targeted-selected ion monitoring with data-dependent fragmentation (t-SIM/dd2), and parallel reaction monitoring. In order to challenge the HR-MS platform, the sample preparation was kept as simple as possible, limited to a 30-min ultrasound-aided protein extraction followed by clean-up with disposable size exclusion cartridges. Selected peptide markers tracing for five allergenic ingredients namely skim milk, whole egg, soy flour, ground hazelnut, and ground peanut were monitored in home-made cookies chosen as model processed matrix. Timed t-SIM/dd2 was found the best choice as a good compromise between sensitivity and accuracy, accomplishing the detection of 17 peptides originating from the five allergens in the same run. The optimized method was validated in-house through the evaluation of matrix and processing effects, recoveries, and precision. The selected quantitative markers for each allergenic ingredient provided quantification of 60-100μgingred/g allergenic ingredient/matrix in incurred cookies.

Fabrication of a Lab-on-Chip Device Using Material Extrusion (3D Printing) and Demonstration via Malaria-Ab ELISA.

Additive manufacturing, such as fused deposition modeling (FDM), has been increasingly employed to produce microfluidic platforms due to ease of use, wide distribution of affordable 3D printers and relatively inexpensive materials for printing. In this work, we discuss fabrication and testing of an FDM-printed fully automated colorimetric enzyme-linked immunosorbent assay (ELISA) designed to detect malaria. The detection platform consists of a disposable 3D-printed fluidic cartridge (with elastomeric silicone domes on top of reagent-storage reservoirs) and a nondisposable frame with servomotors and electronic controls such as an Arduino board and a rechargeable battery. The system is controlled by a novel interface where a music file (so-called “song”) is sent to the Arduino board, where the onboard program converts the set of frequencies into action of individual servomotors to rotate their arms a certain amount, thus depressing specific elastomeric domes atop reagent reservoirs and displacing the specific reagents into the detection wells, where bioassay steps are executed. Another of the distinguished characteristics of the demonstrated system is its ability to aspirate the fluid from the detection wells into the waste reservoir. Therefore, the demonstrated automated platform has the ability to execute even the most complex multi-step assays where dilution and multiple washes are required. Optimization of 3D-printer settings and ways to control leakages typical of FDM-printed fluidic systems are also discussed.

Development of Flow Injection Spectrophotometric Method for 1-Napthylthiourea Using Sodium Nitrite and Sulphanilic Acid Diazotization Reaction

A simple spectrophotometric method in conjunction with flow injection analysis is developed for the quantitative analysis of 1-napthylthiourea (ANTU). The reaction is based on the alkaline hydrolysis of ANTU to 1-naphthylamine at 30°C, coupled with diazotized sulphanilic acid resulting in 4-(sulphophenylazo)-1-naphthylamine which is monitored at 495 nm. The limit of detection (S/N = 3) is 0.01 mg/L with a sampling throughput of 45/h. The method is linear over the range of 0.05–120 mg/L (R2=0.9995,n=7), with calibration equation y = 0.031x−0.018 (y = absorbance; x = mg/L) and relative standard deviation (n=3) 1.8–3.6%. Experimental variables are optimised, and the interfering effects of different pesticides, organic compounds, cations, and anions at environmentally relevant concentrations are investigated. The analysis of ANTU in spiked water samples is extracted with solid phase procedure using disposable Sep-Pak C18 cartridges, and the recovery was 93 ± 1.9–110 ± 3.0%. The results of the proposed method are compared with the HPLC method by applying the F-test and paired Student t-test at 95% confidence level.

Miniaturized Solvent Extraction and Cleanup Method for Polycyclic Aromatic Hydrocarbons in Air Particulate Matter by Gas Chromatography/Mass Spectrometry

Polycyclic aromatic hydrocarbons (PAHs) are one of the priority pollutants measured in atmospheric particles due to their potential health risks to exposed individuals. A miniaturized solvent extraction and cleanup method has been developed for the determination of 14 types of PAHs in air particulate matter (APM) collected through the use of a five-stage stainless steel Berner sampler with aluminum foil as substrates. The analytical method employed sonication of the impacted APM in the aluminum foil substrates with dichloromethane, extract purification through silica cleanup in miniaturized glass columns, and analysis of the PAHs by gas chromatography/mass spectrometry. The performance characteristics of the method such as linearity, range, detection limits and quantification limits, recovery and precision for each of the 14 PAHs were established using procedures suggested by Eurachem and/or the Association of Official Analytical Chemists. The method has direct advantages, i.e., use of minimal volume of solvents, and non-utilization of disposable silica solid phase extraction cartridges, but with performance characteristics that are within acceptable limits−thus resulting in a low-cost, practical, and reliable protocol that can quantify PAHs in APM.

A multiplex reverse transcription PCR and automated electronic microarray assay for detection and differentiation of seven viruses affecting swine.

SummaryMicroarray technology can be useful for pathogen detection as it allows simultaneous interrogation of the presence or absence of a large number of genetic signatures. However, most microarray assays are labour‐intensive and time‐consuming to perform. This study describes the development and initial evaluation of a multiplex reverse transcription (RT)‐PCR and novel accompanying automated electronic microarray assay for simultaneous detection and differentiation of seven important viruses that affect swine (foot‐and‐mouth disease virus [FMDV], swine vesicular disease virus [SVDV], vesicular exanthema of swine virus [VESV], African swine fever virus [ASFV], classical swine fever virus [CSFV], porcine respiratory and reproductive syndrome virus [PRRSV] and porcine circovirus type 2 [PCV2]). The novel electronic microarray assay utilizes a single, user‐friendly instrument that integrates and automates capture probe printing, hybridization, washing and reporting on a disposable electronic microarray cartridge with 400 features. This assay accurately detected and identified a total of 68 isolates of the seven targeted virus species including 23 samples of FMDV, representing all seven serotypes, and 10 CSFV strains, representing all three genotypes. The assay successfully detected viruses in clinical samples from the field, experimentally infected animals (as early as 1 day post‐infection (dpi) for FMDV and SVDV, 4 dpi for ASFV, 5 dpi for CSFV), as well as in biological material that were spiked with target viruses. The limit of detection was 10 copies/μl for ASFV, PCV2 and PRRSV, 100 copies/μl for SVDV, CSFV, VESV and 1,000 copies/μl for FMDV. The electronic microarray component had reduced analytical sensitivity for several of the target viruses when compared with the multiplex RT‐PCR. The integration of capture probe printing allows custom onsite array printing as needed, while electrophoretically driven hybridization generates results faster than conventional microarrays that rely on passive hybridization. With further refinement, this novel, rapid, highly automated microarray technology has potential applications in multipathogen surveillance of livestock diseases.

Highly efficient solid phase supported radiosynthesis of [11 C]PiB using tC18 cartridge as a "3-in-1" production entity.

Pittsburgh compound B ([11 C]PiB) is the gold standard positron emission tomography (PET) tracer for the in vivo imaging of amyloid plaques. Currently, it is synthesized by either solution chemistry or using a "dry loop" approach followed by HPLC purification within 30minutes starting from [11 C]CO2 . Here, we report a novel, highly efficient solid phase supported carbon-11 radiolabeling procedure using commercially available disposable tC18 cartridge as a "3-in-1" entity: reactor, purifier, and solvent replacement system. [11 C]PiB is synthesized by passing gaseous [11 C]CH3 OTf through a tC18 cartridge preloaded with a solution of precursor. Successive elution with aqueous ethanol solutions allows for nearly quantitative separation of the reaction mixture to provide chemically and radiochemically pure PET tracer. [11 C]PiB suitable for human injection is produced within 10minutes starting from [11 C]CH3 OTf (20min from [11 C]CO2 ) in 22% isolated yield not corrected for decay and molar activity of 190GBq/μmol using 0.2mg of precursor. This technique reduces the amount of precursor and other supplies, avoids use of preparative HPLC and toxic solvents, and decreases the time between consecutive production batches. Solid phase supported technique can facilitate [11 C]PiB production compliant with Good Manufacturing Practice (GMP) and improve synthesis reliability.

Validation of the i-STAT®1 Analyzer for Postmortem Vitreous Humor Electrolytes and Glucose Analysis.

The analytical value of vitreous humor as a specimen in postmortem forensic toxicology has been known for some time. Numerous medical examiner laboratories outsource the analysis of this important specimen for electrolyte and glucose measurements. This can be both time-consuming and costly. The utility of the i-STAT®1 medical device to measure electrolytes and glucose in whole blood samples has been demonstrated for over two decades in a clinical setting through single-use disposable cartridges that introduce samples to the i-STAT®1. Different cartridge types allow for the analysis of various analytes including sodium, potassium, chloride, creatinine, urea nitrogen and glucose. With only 100 μL of sample, results are obtained in under 4 min. In this study, we utilized the i-STAT®1 using an alternative specimen matrix, postmortem vitreous humor and quantitatively determined the validity and reliability of the instrument for this purpose. Acceptable criterion was used for each test as suggested by the Scientific Working Group for Forensic Toxicology. All analytes of interest, except creatinine, demonstrated a percent error < ±10% for both accuracy and precision studies. Drug interference and stability studies were performed with many of the analytes demonstrating a percent error < ±20%. Throughout drug interference and stability studies, all analytes of interest were detectable except for potassium, which gave inconclusive results. Significant interference with commonly found drugs were shown for creatinine and chloride but must be evaluated carefully. Volume additions to ethanol spiked samples caused significant interference for all analytes and is considered a limitation for this method of analysis that requires additional studies. As vitreous humor continues to be used in forensic medicine to aid in diagnostic interpretation, the i-STAT®1 has the potential to give accurate results in a timely and cost-effective manner.

Coagulation measurement from whole blood using vibrating optical fiber in a disposable cartridge.

In clinics, blood coagulation time measurements are performed using mechanical measurements with blood plasma. Such measurements are challenging to do in a lab-on-a-chip (LoC) system using a small volume of whole blood. Existing LoC systems use indirect measurement principles employing optical or electrochemical methods. We developed an LoC system using mechanical measurements with a small volume of whole blood without requiring sample preparation. The measurement is performed in a microfluidic channel where two fibers are placed inline with a small gap in between. The first fiber operates near its mechanical resonance using remote magnetic actuation and immersed in the sample. The second fiber is a pick-up fiber acting as an optical sensor. The microfluidic channel is engineered innovatively such that the blood does not block the gap between the vibrating fiber and the pick-up fiber, resulting in high signal-to-noise ratio optical output. The control plasma test results matched well with the plasma manufacturer's datasheet. Activated-partial-thromboplastin-time tests were successfully performed also with human whole blood samples, and the method is proven to be effective. Simplicity of the cartridge design and cost of readily available materials enable a low-cost point-of-care device for blood coagulation measurements.

C2 Balloon Cryotherapy for Symptom Relief in Esophageal Squamous Cell Carcinoma: A Novel Approach: 2017 Presidential Poster Award

Introduction: Focal cryoballoon ablation therapy is a relatively new modality that has been reported in treatment of Barrett's esophagus and esophageal squamous cell neoplasia. It is safe and well-tolerated by patients. Here we report a case that highlights the rare use of C2 cryoballoon cryotherapy for symptoms relief in a patient with malignant dysphagia. Case: A 70 year-old female with medical history of atrial fibrillation and hyperplastic colonic polyps presented with a 5-week history of odynophagia and subsequent dysphagia with solids and liquids associated with increasing lower substernal chest pain and 20-lb of weight loss. Patient was found to have a poorly differentiated squamous cell carcinoma in the distal third of the esophagus from 33 to 38 cm with narrowing of the lumen but not fully obstructed. A CT scan demonstrated extensive mediastinal and gastrohepatic lymph node involvement but no metastases to the lungs or liver. In light of worsening of esophageal symptoms, she was initially referred for possible esophageal stent placement. On EGD, a near circumferential fungating mass was found in the lower third of the esophagus, consistent with established locally advanced squamous cell carcinoma of esophagus. Balloon-based TTS (C2 focal catheter) cryotherapy was applied in 6 sessions to the entire lesion using 12 seconds applications. Patient tolerated the procedures well with no complications and was discharged on a soft diet. Esophageal symptoms were greatly alleviated and she was to continue to follow with Oncology and Radiation Oncology.Figure: Circumferential fungating mass in distal third of esophagusFigure: Balloon-based through-the-scope (C2 focal catheter)Discussion: Cryoballoon Focal Ablation System is a novel through-the-scope, balloon catheter, easy-to-use, obviating the need for sizing, with a handle and a small disposable cryogen cartridge. It has been developed for treatment of Barrett's esophagus, including refractory disease, and potentially of esophageal squamous cell carcinoma. We described a case revealing the rare and unique use of C2 balloon cryotherapy for symptoms relief in a patient with locally advanced squamous cell carcinoma of the esophagus. For palliation of malignant dysphagia, esophageal stents are widely used despite their myriad complications. As highlighted in this case, focal cryoballoon ablation is a novel and promising therapy that is relatively safe and effective in achieving resolution of symptoms.Figure: Ablation of esophageal fungating mass using a Balloon-based TTS (C2 focal catheter)

Direct Analysis of Aerosolized Chemical Warfare Simulants Captured on a Modified Glass-Based Substrate by "Paper-Spray" Ionization.

Paper spray ionization mass spectrometry offers a rapid alternative platform requiring no sample preparation. Aerosolized chemical warfare agent (CWA) simulants trimethyl phosphate, dimethyl methylphosphonate, and diisopropyl methylphosphonate were captured by passing air through a glass fiber filter disk within a disposable paper spray cartridge. CWA simulants were aerosolized at varying concentrations using an in-house built aerosol chamber. A custom 3D-printed holder was designed and built to facilitate the aerosol capture onto the paper spray cartridges. The air flow through each of the collection devices was maintained equally to ensure the same volume of air sampled across methods. Each approach yielded linear calibration curves with R2 values between 0.98-0.99 for each compound and similar limits of detection in terms of disbursed aerosol concentration. While the glass fiber filter disk has a higher capture efficiency (≈40%), the paper spray method produces analogous results even with a lower capture efficiency (≈1%). Improvements were made to include glass fiber filters as the substrate within the paper spray cartridge consumable. Glass fiber filters were then treated with ammonium sulfate to decrease chemical interaction with the simulants. This allowed for improved direct aerosol capture efficiency (>40%). Ultimately, the limits of detection were reduced to levels comparable to current worker population limits of 1 × 10-6 mg/m3.

Optical sensing of anticoagulation status: Towards point-of-care coagulation testing.

Anticoagulant overdose is associated with major bleeding complications. Rapid coagulation sensing may ensure safe and accurate anticoagulant dosing and reduce bleeding risk. Here, we report the novel use of Laser Speckle Rheology (LSR) for measuring anticoagulation and haemodilution status in whole blood. In the LSR approach, blood from 12 patients and 4 swine was placed in disposable cartridges and time-varying intensity fluctuations of laser speckle patterns were measured to quantify the viscoelastic modulus during clotting. Coagulation parameters, mainly clotting time, clot progression rate (α-angle) and maximum clot stiffness (MA) were derived from the clot viscoelasticity trace and compared with standard Thromboelastography (TEG). To demonstrate the capability for anticoagulation sensing in patients, blood samples from 12 patients treated with warfarin anticoagulant were analyzed. LSR clotting time correlated with prothrombin and activated partial thromboplastin time (r = 0.57–0.77, p<0.04) and all LSR parameters demonstrated good correlation with TEG (r = 0.61–0.87, p<0.04). To further evaluate the dose-dependent sensitivity of LSR parameters, swine blood was spiked with varying concentrations of heparin, argatroban and rivaroxaban or serially diluted with saline. We observed that anticoagulant treatments prolonged LSR clotting time in a dose-dependent manner that correlated closely with TEG (r = 0.99, p<0.01). LSR angle was unaltered by anticoagulation whereas TEG angle presented dose-dependent diminution likely linked to the mechanical manipulation of the clot. In both LSR and TEG, MA was largely unaffected by anticoagulation, and LSR presented a higher sensitivity to increased haemodilution in comparison to TEG (p<0.01). Our results establish that LSR rapidly and accurately measures the response of various anticoagulants, opening the opportunity for routine anticoagulation monitoring at the point-of-care or for patient self-testing.

Rapid Nucleic Acid Extraction and Purification Using a Miniature Ultrasonic Technique.

Miniature ultrasonic lysis for biological sample preparation is a promising technique for efficient and rapid extraction of nucleic acids and proteins from a wide variety of biological sources. Acoustic methods achieve rapid, unbiased, and efficacious disruption of cellular membranes while avoiding the use of harsh chemicals and enzymes, which interfere with detection assays. In this work, a miniature acoustic nucleic acid extraction system is presented. Using a miniature bulk acoustic wave (BAW) transducer array based on 36° Y-cut lithium niobate, acoustic waves were coupled into disposable laminate-based microfluidic cartridges. To verify the lysing effectiveness, the amount of liberated ATP and the cell viability were measured and compared to untreated samples. The relationship between input power, energy dose, flow-rate, and lysing efficiency were determined. DNA was purified on-chip using three approaches implemented in the cartridges: a silica-based sol-gel silica-bead filled microchannel, nucleic acid binding magnetic beads, and Nafion-coated electrodes. Using E. coli, the lysing dose defined as ATP released per joule was 2.2× greater, releasing 6.1× more ATP for the miniature BAW array compared to a bench-top acoustic lysis system. An electric field-based nucleic acid purification approach using Nafion films yielded an extraction efficiency of 69.2% in 10 min for 50 µL samples.

Filtration characteristics of threaded microfiber water filters

Textile fibers are widely used for fine filtration in the disposable cartridge filter market. In this work the filtration mechanism of threaded microfiber water filters was characterized by testing the effect of filtration velocity, slurry concentration, particles size distribution (PSD) and filter pore size and porosity, on the filter performance. Constant flow rate experiments were conducted with micronized CaCO3 slurry as a model substance. It was found that the predominant filtration mechanism of the studied filters is cake filtration. Very efficient filtration followed by effective automatic cleaning of the filter was obtained as indicated by complete removal of the CaCO3 particles in all the conditions studied and similar clean filter resistance over repetitive cycles. Shorter filtration cycles were obtained at higher velocities, low porosity filter and narrow PSD. Correspondingly, the filter capacity declined as the filtration cycles were shorter. Yet, the filter capacity was found to be independent of the CaCO3 slurry concentration. A criterion of specific consumed energy per unit filtrate volume (Es) was developed. Analyses of the effect of the various studied parameters on Es revealed its dependence on the slurry concentration, velocity and filtration time.

Low-cost humic acid-bonded silica as an effective solid-phase extraction sorbent for convenient determination of aflatoxins in edible oils

Aflatoxins (AFs) are highly toxic, mutagenic, carcinogenic, and teratogenic secondary metabolites produced by the toxigenic fungi Aspergillus flavus and Aspergillus parasiticus. AFs tend to contaminate a wide range of foods which is a serious and recurring food safety problem worldwide. Currently, immunoaffinity chromatography (IAC) has become the most conventional sample clean-up method for determining AFs in foodstuffs. However, IAC method is limited in the large-scale food analysis because it requires the use of expensive disposable cartridges and the IA procedure is time-consuming. Herein, to achieve the cost-effective determination of AFs in edible oils, we developed a promising solid-phase extraction (SPE) method based on commercially available humic acid-bonded silica (HAS) sorbent, followed by high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) analysis. In HAS-SPE, AFs can be captured by the HAS sorbent with both hydrophobic and hydrophilic interactions, whereas the oil matrix was captured only with the hydrophobic interactions. The oil matrix can be sufficiently washed off with isopropanol, while the AFs were still retained on the SPE packing, thus achieving selective extraction of AFs and clean-up of oil matrices. Under the optimal conditions of HAS-SPE, satisfactory recoveries ranging from 82% to 106% for four AFs (B1, B2, G1, and G2) were achieved in various oil matrices, containing blended oil, tea oil, rapeseed oil, peanut oil, sunflower seed oil, corn oil, blended olive oil, rice oil, soybean oil, and sesame oil. Only minor matrix effects ranging from 99% to 105% for four AFs were observed. Moreover, the LODs of AFs between 0.012 and 0.035 μg/kg completely meet the regulatory levels fixed by the EU, China or other countries. The methodology was further validated for assaying the naturally contaminated peanut oils, and consistent results between the HAS-SPE and the referenced IAC were obtained. In addition, HAS-SPE can directly treat diluted oil sample without liquid-liquid extraction and is automatable, thus making it simple and convenient for the large-scale determination of AFs in edible oils. Using this method, we successfully detected four AFs in the naturally contaminated peanut oils, which is, to the best of our knowledge, the first report about the determination of AFs in edible oils using HA-based SPE.

Smartphone–based enzymatic biosensor for oral fluid L-lactate detection in one minute using confined multilayer paper reflectometry

The development of smartphone–based biosensors for point-of-care testing (POCT) applications allows realizing “all in one” instruments, with large potential distribution among the general population. With this respect, paper color-based detection performed by reflectance measurement is the most popular, simple, inexpensive and straightforward method. Despite the large number of scientific publications related to these biosensors, they still suffer from a poor detectability and reproducibility related to inhomogeneity of color development, which leads to low assay reproducibility. To overcome these problems, we propose a smartphone paper-based biosensor, in which all the reagents necessary to complete the analysis are co-entrapped on paper in a “wafer”-like bilayer film of polyelectrolytes (Poly (allyl amine hydrochloride/poly(sodium 4-styrene sulfonate)). Using a 3D printing low-cost technology we fabricated the smartphone-based device that consists in a cover accessory attached to the smartphone and incorporating a light diffuser over the flash to improve the image quality, a mini dark box and a disposable analytical cartridge containing all the reagents necessary for the complete analysis. The biosensor was developed exploiting coupled enzyme reactions for quantifying L-lactate in oral fluid, which is considered a biomarker of poor tissue perfusion, a key element in the management of severe sepsis, septic shock and in sports performance evaluation. The developed method is sensitive, rapid, and it allows detecting L-lactate in oral fluid in the relevant physiological range, with a limit of detection of 0.1mmolL−1. The extreme simplicity of assay execution (no reagents need to be added) and flexibility of fabrication of the device, together with the high assay versatility (any oxidase can be coupled with HRP-based color change reaction) make our approach suitable for the realization of smartphone-based biosensors able to non-invasively detect a large variety of analytes of clinical interest.

A fully integrated microfluidic platform for highly sensitive analysis of immunochemical parameters.

We present a novel fully integrated centrifugal microfluidic platform for highly sensitive immunoassays in point-of-care settings. The platform consists of a disposable cartridge containing structures for assay processing, a porous membrane and all dried reagents required for the analysis. Additionally, a blister containing a washing buffer is connected to a new aliquoting structure enabling the serial aliquoting of washing buffer for repetitive bound-free separation steps. The proof-of-concept for two immunoassays is shown in the cartridge with each requiring only 30 μL of whole blood or plasma as the sample material. The detection of the cardiac marker Troponin T with a functional sensitivity of 7.55 ng L-1 (cv = 10%) within 11 minutes is shown based on samples from ten donors which were measured with six breadboard instruments to prove the platform capability for highly sensitive measurements at diagnostic relevant concentrations. Furthermore an assay for the cardiac marker NT-proBNP (five donors, six instruments) with a time-to-result of 12 minutes demonstrates that high-titer analytes (43 to 16.566 ng L-1) can be measured as well. A method comparison of our platform with a state-of-the-art laboratory analyzer proves an excellent correlation of the measured analyte concentrations. All results are obtained from injection moulded cartridges and all components of the platform are compatible for mass production.