Micropump integrated white blood cell separation platform for detection of chronic granulomatous disease.

White blood cells (WBCs) are robust defenders during antigenic challenges and prime immune cell functioning indicators. High-purity WBC separation is vital for various clinical assays and disease diagnosis. Red blood cells (RBCs) are a major hindrance in WBC separation, constituting 1000 times the WBC population. The study showcases a low-cost micropump integrated microfluidic platform to provide highly purified WBCs for point-of-care testing. An integrated user-friendly microfluidic platform was designed to separate WBCs from finger-prick blood (⁓5 µL), employing an inertial focusing technique. We achieved an efficient WBC separation with 86% WBC purity and 99.99% RBC removal rate in less than 1 min. In addition, the microdevice allows lab-on-chip colorimetric evaluation of chronic granulomatous disease (CGD), a rare genetic disorder affecting globally. The assay duration, straight from separation to disease detection, requires only 20 min. Hence, the proposed microfluidic platform can further be implemented to streamline various clinical procedures involving WBCs in healthcare industries.

A portable microfluidic device-based Fe3O4-urease nanoprobe-enhanced colorimetric sensor for the detection of heavy metals in fish tissue.

A portable microfluidic device with highly sensitive enzyme nanoprobe (Fe3O4 MNPs-urease, average size 34.6 nm) was demonstrated for the analysis of heavy metals ions (Hg2+, Cd2+ and Pb2+) in fish gill and muscle tissue. The immobilized urease nanoprobe (Km = 0.05 mM) exhibited twofold sensitivity over the free enzyme assay (apparent Km = 0.1 mM). The nanoprobe was characterized using SEM, EDAX, PSA and FT-IR. The inhibition measurements were carried out for individual as well as the mixture of metal ions (CRM standards of 9 elements (CRMmix-9)). The lower limit of quantification (LOQ) (0.5, 0.1, and 0.1 ng L-1 for Hg2+, Cd2+, and Pb2+) and lower limit of detection (LOD) was achieved at 0.1 ng L-1 with sensitivity 8-14% per decade for Hg2+, Cd2+, and Pb2+ ions. A visual result can be observed by the naked eye through the microfluidic device as well as with 96 transparent microwell plates. The order of relative inhibition was found to be CRMmix-9 > (Hg2+ + Cd2+ + Pb2+) > (Cd2+ + Pb2+) > (Pb2+ + Hg2+) > (Hg2+ + Cd2+) > Pb2+ > Cd2+ > Hg2+, respectively. The recovery % in fish tissues were found to be 88-98% for Hg2+, Cd2+ and Pb2+ ions.

Nanoimmunosensor based on ZnO nanorods for ultrasensitive detection of 17ß-Estradiol.

Advances in nanostructured materials have facilitated the development of novel sensitive techniques for detection of environmental and clinical analytes. There is immense need for development of devices that can detect analytes at concentrations as low as few pg mL-1. The comparable size of nanostructured materials and biomolecules enabled the integration of biological systems with nanometer sized structures. Herein, we demonstrate a Zinc Oxide nanorods (ZnONRs) integrated ultrasensitive label-free biosensor with femtomolar (0.01 pg mL-1) sensitivity for the endocrine disruptor 17ß-Estradiol (E2). The ZnONRs, average width 50 nm and length 325 nm, were grown on the silver electrode surface (Ag-ZnONRs). Monoclonal antibodies of E2 (mAb-E2) were covalently immobilized on ZnONRs surface and measured using electrochemical impedance spectroscopy (EIS). A linear detection range of 0.1-200 pg mL-1 for E2 with R2 = 0.99 and % RSD = 4.35 (n = 3, assay volume 90 µL) was achieved for the developed nano-sensing system. A significant enhancement in the sensitivity was achieved in the presence of ZnONRs, enabling the limit of quantification down to 0.1 pg mL-1 with 2.7 % capacitance change per decade. In addition, a further increase in sensitivity due to assay volume reduction (20 µL) was observed enabling further scope of miniaturization.

Flow injection analysis biosensor for urea analysis in urine using enzyme thermistor.

There is a need for analytical methods capable of monitoring urea levels in urine for patients under clinical monitoring to appraise renal function. Herein, we present a practical method to quantify levels of urea in human urine samples using flow injection analysis-enzyme thermistor (FIA-ET) biosensor. The biosensor comprises a covalently immobilized enzyme urease (Jack bean) on aminated silica support, which selectively hydrolyzes the urea present in the sample. Under optimized conditions, the developed biosensor showed a linear response in the range of 10-1,000 mM, R (2) = 0.99, and response time of 90 s in 100 mM phosphate buffer (PB) (flow rate of 0.5 mL/min, sample volume of 0.1 mL, and pH 7.2). The urea-spiked human urine samples showed minimal matrix interference in the range of 10-1,000 mM. Recoveries were obtained (92.26-99.80 %) in the spiked urine samples. The reliability and reproducibility of the developed biosensor were found satisfactory with percent relative standard deviation (% RSD) = 0.741. The developed biosensor showed excellent operational stability up to 30 weeks with 20 % loss in original response when used continuously at room temperature. These results indicate that the developed biosensor could be very effective to detect low and high levels of urea in urine samples.

A novel automated flow-based biosensor for the determination of organophosphate pesticides in milk.

This work describes the development of an automated flow-based biosensor that employs genetically modified acetylcholinesterase (AChE) enzymes B394, B4 and wild type B131. The biosensor was based on a screen printed carbon electrode (SPE) that was integrated into a flow cell. Enzymes were immobilised on cobalt (II) phthalocyanine (CoPC) modified electrodes by entrapment in a photocrosslinkable polymer (PVA-AWP). The automated flow-based biosensor was successfully used to quantify three organophosphate pesticides (OPs) in milk samples. The OPs used were chlorpyriphos-oxon (CPO), ethyl paraoxon (EPOx) and malaoxon (MOx). The total analysis time for the assay was less than 15 min. Initially, the biosensor performance was tested in phosphate buffer solution (PBS) using B394, B131 and B4 biosensors. The best detection limits were obtained with B394; therefore, this biosensor was used to produce calibration data in milk with three OPs in the concentration range of 5 × 10(-6)M to 5 × 10(-12)M. The limit of detection (LOD) obtained in milk for CPO, EPOx and MOx were 5 × 10(-12)M, 5 × 10(-9)M and 5 × 10(-10)M, respectively, with a correlation coefficient R(2)=0.9910. The automated flow-based biosensor successfully quantified the OPs in different fat-containing milk samples. There were no false positives or false negatives observed for the analytical figures of merit for the constructed biosensors. This method is inexpensive, sensitive, portable, non-invasive and provides real-time results. This analytical system can provide rapid detection of highly toxic OPs in food matrices such as milk.