Microfluidics-based rapid measurement of nitrite in human blood plasma

We report direct and rapid measurement of nitrite in human blood plasma using a fluorescence-based microfluidic method.

Direct and rapid measurement of hydrogen peroxide in human blood using a microfluidic device

The levels of hydrogen peroxide (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$\end{document}H2O2) in human blood is of great relevance as it has emerged as an important signalling molecule in a variety of disease states. Fast and reliable measurement of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$\end{document}H2O2 levels in the blood, however, continues to remain a challenge. Herein we report an automated method employing a microfluidic device for direct and rapid measurement of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$\end{document}H2O2 in human blood based on laser-induced fluorescence measurement. Our study delineates the critical factors that affect measurement accuracy—we found blood cells and soluble proteins significantly alter the native \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$\end{document}H2O2 levels in the time interval between sample withdrawal and detection. We show that separation of blood cells and subsequent dilution of the plasma with a buffer at a ratio of 1:6 inhibits the above effect, leading to reliable measurements. We demonstrate rapid measurement of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$\end{document}H2O2 in plasma in the concentration range of 0–49 µM, offering a limit of detection of 0.05 µM, a sensitivity of 0.60 µM⁻¹, and detection time of 15 min; the device is amenable to the real-time measurement of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$\end{document}H2O2 in the patient’s blood. Using the linear correlation obtained with known quantities of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$\end{document}H2O2, the endogenous \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$\end{document}H2O2 concentration in the blood of healthy individuals is found to be in the range of 0.8–6 µM. The availability of this device at the point of care will have relevance in understanding the role of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\mathrm{H}}_{2}{\mathrm{O}}_{2}$$\end{document}H2O2 in health and disease.

An optomicrofluidic device for the detection and isolation of drop-encapsulated target cells in single-cell format

Single-cell analysis has emerged as a powerful method for genomics, transcriptomics, proteomics, and metabolomics characterisation at the individual cell level. Here, we demonstrate a technique for the detection and selective isolation of target cells encapsulated in microdroplets in single-cell format. A sample containing a mixed population of cells with fluorescently labelled target cells can be focused using a sheath fluid to direct cells in single file toward a droplet junction, wherein the cells are encapsulated inside droplets. The droplets containing the cells migrate toward the centre of the channel owing to non-inertial lift force. The cells present in the droplets are studied and characterised based on forward scatter (FSC), side scatter (SSC), and fluorescence (FL) signals. The FL signals from the target cells can be used to activate a selective isolation module based on electro-coalescence, using suitable electronics and a program to sort droplets containing the target cells in single-cell format from droplets containing background cells. We demonstrated the detection and isolation of target cells (cancer cells: HeLa and DU145) from mixed populations of cells, peripheral blood mononuclear cells (PBMC) + cervical cancer cells (HeLa) and PBMC + human prostate cancer cells (DU145), at a concentration range of 104-106 ml-1 at 300 cells per s. The performance of the device is characterised in terms of sorting efficiency (>97%), enrichment (>1800×), purity (>98%), and recovery (>95%). The sorted target cells were found to be viable (>95% viability) and showed good proliferation when cultured, showing the potential of the proposed sorting technique for downstream analysis.

Rapid measurement of hydrogen sulphide in human blood plasma using a microfluidic method

Hydrogen sulfide (H₂S) is emerging as an important gasotransmitter in both physiological and pathological states. Rapid measurement of H₂S remains a challenge. We report a microfluidic method for rapid measurement of sulphide in blood plasma using Dansyl-Azide, a fluorescence (FL) based probe. We have measured known quantities of externally added (exogenous) H₂S to both buffer and human blood plasma. Surprisingly, a decrease in FL intensity with increase in exogenous sulphide concentration in plasma was observed which is attributed to the interaction between the proteins and sulphide present in plasma underpinning our observation. The effects of mixing and incubation time, pH, and dilution of plasma on the FL intensity is studied which revealed that the FL assay required a mixing time of 2 min, incubation time of 5 min, a pH of 7.1 and performing the test within 10 min of sampling; these together constitute the optimal parameters at room temperature. A linear correlation (with R² ≥ 0.95) and an excellent match was obtained when a comparison was done between the proposed microfluidic and conventional spectrofluorometric methods for known concentrations of H₂S (range 0–100 µM). We have measured the baseline level of endogenous H₂S in healthy volunteers which was found to lie in the range of 70 μM – 125 μM. The proposed microfluidic device with DNS-Az probe enables rapid and accurate estimation of a key gasotransmitter H₂S in plasma in conditions closely mimicking real time clinical setting. The availability of this device as at the point of care, will help in understanding the role of H₂S in health and disease.

Formulation and Evaluation of Almotriptan Malate Nasal Drops

Nasal solutions of almotriptan malate were prepared in phosphate buffer containing different proportions of HPMC E15. In vitro permeation studies were performed using Franz diffusion cell with dialysis membrane and ex vivo permeation studies were carried out using sheep nasal mucosal layer. The formulations were radiolabeled with 99mTc and the nasal residence time was studied in rabbits. Nasal irritation was evaluated in rats. Formulations prepared with HPMC E15 5% w/v did not retard the release of almotriptan. Gamma scintigraphy studies showed increased residence time as compared to plain drug solution. No nasal irritation was observed and the formulations were found stable for 3 months.

The TAR model: use of therapeutic state transitions for quality assurance reporting in chronic disease management

Chronic disease management represents one of the challenges for health informatics and demands the appropriate application of information technology for improved patient care. This paper presents an approach to quality assurance reporting wherein the recommendations of evidence-based clinical practice guidelines are considered in the context of empirical therapeutic state-transitions (in terms of changes in individual patient prescriptions over time). We apply a Transition-based Audit Report (TAR) model to antihypertensive prescribing and related data as stored in a New Zealand General Practice Management System database. The results provide a set of quality indicators and specific patient cohorts for potential practice quality improvement with strong linkage to the selected guidelines and observed practice patterns. We see the TAR model primarily as a tool to enable internal quality improvement efforts, but also to be of relevance for focusing pay-for-performance programs.