Water-based alkyl ketene dimer ink for user-friendly patterning in paper microfluidics

We propose the use of water-based alkyl ketene dimer (AKD) ink for fast and user-friendly patterning of paper microfluidic devices either manually or using an inexpensive XY-plotter. The ink was produced by dissolving hydrophobic AKD in chloroform and emulsifying the solution in water. The emulsification was performed in a warm water bath, which led to an increased rate of the evaporation of chloroform. Subsequent cooling led to the final product, an aqueous suspension of fine AKD particles. The effects of surfactant and AKD concentrations, emulsification procedure, and cooling approach on final ink properties are presented, along with an optimized protocol for its formulation. This hydrophobic agent was applied onto paper using a plotter pen, after which the paper was heated to allow spreading of AKD molecules and chemical bonding with cellulose. A paper surface patterned with the ink (10 g L-1 AKD) yielded a contact angle of 135.6° for water. Unlike organic solvent-based solutions of AKD, this AKD ink does not require a fume hood for its use. Moreover, it is compatible with plastic patterning tools, due to the effective removal of chloroform in the production process to less than 2% of the total volume. Furthermore, this water-based ink is easy to prepare and use. Finally, the AKD ink can also be used for the fabrication of so-called selectively permeable barriers for use in paper microfluidic networks. These are barriers that stop the flow of water through paper, but are permeable to solvents with lower surface energies. We applied the AKD ink to confine and preconcentrate sample on paper, and demonstrated the use of this approach to achieve higher detection sensitivities in paper spray ionization-mass spectrometry (PSI-MS). Our patterning approach can be employed outside of the analytical lab or machine workshop for fast prototyping and small-scale production of paper-based analytical tools, for use in limited-resource labs or in the field

Enhanced passive mixing for paper microfluidics

Imprecise control of fluid flows in paper-based devices is a major challenge in pushing the innovations in this area towards societal implementation. Assays on paper tend to have low reaction yield and reproducibility issues that lead to poor sensitivity and detection limits. Understanding and addressing these issues is key to improving the performance of paper-based devices. In this work, we use colorimetric analysis to observe the mixing behaviour of molecules from two parallel flow streams in unobstructed (on unpatterned paper) and constricted flow (through the gap of a patterned hourglass structure). The model system used for characterization of mixing involved the reaction of Fe 3+ with SCN À to form the coloured, soluble complex Fe(SCN)2+ . At all tested concentrations (equal concentrations of 50.0 mM, 25.0 mM or 12.5 mM for KSCN and FeCl 3 in each experiment), the reaction yield increases (higher colorimetric signal) and better mixing is obtained (lower relative standard deviation) as the gap of the flow constriction becomes smaller (4.69–0.32 mm). This indicates enhanced passive mixing of reagents. A transition window of gap widths exhibiting no mixing enhancement (about 2 mm) to gap widths exhibiting complete mixing (0.5 mm) is defined. The implementation of gap sizes that are smaller than 0.5 mm (below the transition window) for passive mixing is suggested as a good strategy to obtain complete mixing and reproducible reaction yields on paper. In addition, the hourglass structure was used to define the ratio of reagents to be mixed (2 : 1, 1 : 1 and 1 : 2 HCl–NaOH) by simply varying the width ratio of the input channels of the paper. This allows easy adaptation of the device to reaction stoichiometry

Analysis of illicit drugs in municipal wastewater using LCMS/MS: A method validation study

An analytical method based on solid-phase extraction (SPE) liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the determination of five illicit drugs, namely amphetamine (AM), methamphetamine (MA), 3,4- methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA), and morphine (MOR) in municipal wastewater has been optimized and validated. Sample preparation was performed using Oasis MCX SPE cartridges. LC separation was performed using a Zorbax Eclipse Plus C18 RRHD column. The linearity of the calibration curve was between 5 ng/mL and 250 ng/mL, with determination coefficient (R2 ) greater than 0.99, except for morphine. The mean recoveries of target analytes ranged from 91.6 to 112%, and the method demonstrated good inter-day repeatability (coefficient of variation, CV ranged from 2 to 19%). The limit of detection (LOD) for AM, MA, MDMA, MDA, and MOR was 0.29, 0.37, 0.86, 1.09 and 7.56 ng/mL, respectively. The method was applied to municipal wastewater samples collected from sewage treatment plants in Kuantan, Pahang, in which AM, MA and MDA were detected in all 3 samples

Urinary apolipoprotein A1 and its potential as a biomarker for coronary artery disease in young adults

INTRODUCTION: Very few studies have focused on exploring the utilisation of urinary protein biomarkers to improve the risk stratification of coronary artery disease (CAD) in young adults. Apolipoprotein A1 (ApoA1) as a primary constituent protein of Highdensity Lipoprotein (HDL) known to modulate cholesterol metabolism exhibits promising properties to be used as a protein biomarker, specifically for CAD in young adults. Thus, this study is aimed to evaluate the potential of urinary ApoA1 as a urinary biomarker of CAD in young patients with acute myocardial infarction (AMI). MATERIALS AND METHOD: This case-control study recruited 40 newly diagnosed AMI patients and 40 healthy control subjects aged 18–45. Urine samples were collected from all subjects. Once centrifuged, the supernatant was collected and stored at -80 °C until further analysis. The urinary concentration of ApoA1 was quantified using the ApoA1 Enzyme-linked Immunosorbent Assay (ELISA) kit according to the manufacturer's protocol. All subjects' risk factors were determined and documented, such as smoking status, Body Mass Index (BMI), blood pressure, plasma total cholesterol, and glucose levels. RESULTS: The mean age of AMI patients was higher than the controls; 37.1 1 ± 5.2 and 31.6 ± 8.1 years respectively. The mean urinary concentration of ApoA1 of AMI patients was significantly higher than the controls (12. 442 ± 3.571 vs. 10.067 ± 5.606 ng/ mL (p0.05). CONCLUSION: A significant elevation of urinary excretion of ApoA1 in AMI young adults demonstrated its potential use as a urinary protein biomarker for CAD in young adults

Plasma haptoglobin as a potential biomarker for coronary artery disease in young hypertensive adults

Uncontrolled hypertension is one of the recognized risk factors for coronary artery disease (CAD) in young adults, commonly underestimated owing to the young age. A novel biomarker to improve CAD risk assessment and hypertension management should be identified for this cohort. Thus, we had conducted a study to investigate plasma concentration and the role of haptoglobin in young hypertensive adults in the establishment of premature acute myocardial infarction (AMI). MATERIALS AND METHODS: A total of 120 male adults aged between 18 to 45 years enrolled into this cross-sectional study, divided into control, hypertensive, and acute myocardial infarction (AMI) groups. Blood samples were collected from all subjects, plasma concentrations of haptoglobin measured using enzyme-linked immunosorbent assays, and other CAD risk factors including high sensitivity C-reactive protein (hs-CRP) levels were analyzed. RESULTS: Plasma concentration of haptoglobin in the AMI group was the highest compared to hypertensive and control group (290.63±99.90 vs. 208.47±112.93 vs. 170.02±108.11 ng/ml, p<0.006). There was a significant association between AMI and plasma haptoglobin concentration in hypertensive subjects independent of other known CAD risk factors (OR: 0.985, 95% CI 0.973-0.997, p=0.017). There was positive correlation between plasma haptoglobin and hs-CRP (r=0.0370, p<0.001). CONCLUSION: Plasma haptoglobin is a potential biomarker to identify young hypertensive adults who are at risk of developing CAD

Cross-Linking Effect on Electrospun Hydroxyethyl Cellulose/Poly(Vinyl Alcohol) Nanofibrous Scaffolds

The electrospinning of hydroxyethyl cellulose/poly(vinyl alcohol) (HEC/PVA) was carried out with glutaraldehyde as a cross li nker to fabricate water insoluble nanofibers. The concentration of HEC (5wt%) and PVA (15wt%) was prepared and blended in different weight ratios of HEC to PVA (50:50, 40:60 and 70:30) were electrospun to get nanofibers. The microstructure of the obtained nanofibers were analysed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) before and after crosslinking. SEM images showed that there was no swelling or remarkable changes in the surface morphology after treated with glutaraldehyde. XRD analysis il lustrated the effect of crosslinking on the crystallinity of the nanofibers. The results showed that these crosslinked HEC/PVA fibers were suitable for variety of applications such as tissue engineering scaffolds, drug delivery and medical prostheses

Validation of analytical method for testing the levels of illicit drugs in Municipal Wastewater influent samples

Official figures for drug abuse and seizure rates in Malaysia are currently obtained from drug sweep operations carried out by The Royal Malaysia Police (PDRM) in collaboration with The National Antidrug Agency (AADK). This method can provide a useful general picture of drug abuse in our society, but consumption rates and drug use prevalence may be underestimated because the data is obtained directly from consumers. Wastewater-based epidemiology (WBE) has been widely used to objectively monitor population-level drug use, particularly in the Western countries [1-4]. By collecting raw sewage samples from municipal wastewater treatment plants (WWTPs) and quantifying the concentrations of drug residues or its metabolites in the samples, the population-normalized total consumption for a given drug within the population of a sewage treatment service area could be estimated. In this study, an analytical method based on solid phase extraction (SPE) and liquid chromatography tandem mass spectrometry (LC-MS/MS) was validated for the determination of amphetamine (AM), methamphetamine (MA), 3,4-methylenedioxymethamphetamine (MDMA), 3,4-methylenedioxyamphetamine (MDA), and morphine (MOR) in wastewater. The method was tested on sewage samples collected from WWTPs in the Kuantan area to see if it was sensitive enough to detect these compounds. In the future, this method will be applied to assess the consumption of these drugs using the WBE approach

Potential of urinary apolipoprotein A1 as a biomarker for coronary artery disease in young adults

INTRODUCTION: Coronary artery disease (CAD) in young adults associate with significant socio-economic burden to individuals, families and community. Studies on new protein biomarkers to improve risk stratification of CAD in young adults mainly focused on plasma samples, while urinary biomarkers remain minimally researched. Hence, this study aimed to investigate the urinary concentration of Apolipoprotein A1 (ApoA1) in young patients with acute myocardial infarction (AMI). MATERIALS AND METHOD: This study recruited 40 newly diagnosed AMI patients and 40 healthy control subjects aged 18 to 45 years. Urine samples were collected from all subjects and centrifuged. Following removal of the sediment, the supernatant was collected and stored at -80 °C until analysis. The urinary concentration of ApoA1 were measured using the Abcam Human ApoA1 enzyme-linked immunosorbent assay kit. Risk factor profiles for CAD such as smoking status, body mass index, blood pressure, plasma total cholesterol and glucose levels of all subjects were determined and documented. RESULTS: The mean age of AMI patients and the controls was 37.1 ± 5.2, and 31.6 ± 8.1 years, p0.05). CONCLUSION: A significant elevation of urinary excretion of ApoA1 in AMI young adults proposed its potential role as a urinary biomarker for CAD in young adults. Urinary biomarker may serve as an alternative non-invasive approach to recognize early onset of CAD in this cohort

Plasma haptoglobin as a potential biomarker for coronary artery disease in young hypertensive adults

Introduction: Uncontrolled hypertension is a primary risk factor for premature coronary artery disease (CAD) in young adults. The risk of CAD among young hypertensive adults is commonly underestimated owing to the young age. Hence, identification of novel biomarker(s) to improve risk stratification of CAD in young hypertensive adults is essential for more accurate CAD risk assessment and thus to improve management of hypertension in this cohort. This study investigated plasma haptoglobin concentration in young adults with acute myocardial infarction (AMI) and hypertension to evaluate the potential of haptoglobin as a biomarker in the establishment of CAD in young hypertensive adults. Materials and Methods: A total of 120 male young adults aged between 18 to 45 years were enrolled in this cross-sectional study (40 subjects in control, hypertensive and AMI group respectively). Blood samples were collected from all subjects. Plasma concentrations of haptoglobin was measured using enzyme-linked immunosorbent assays. Other CAD risk factors including high sensitivity C-reactive protein (hs-CRP) levels were analyzed. Results: Plasma concentration of haptoglobin in the AMI group was the highest as compared to hypertensive and control group (290.63±99.90 vs. 208.47±112.93 vs. 170.02±108.11 ng/ml, p<0.006). There was a significant association between AMI and plasma haptoglobin concentration in hypertensive subjects independent of other known CAD risk factors (OR: 0.985, 95% CI 0.973-0.997, p=0.017). There was positive correlation between plasma haptoglobin and hs-CRP (r=0.0370, p<0.001). Conclusion: Plasma haptoglobin is a potential biomarker to identify young hypertensive adults who are at risk of developing CAD. (246 words