Real-Time Monitoring of Chemisorption of Antibodies onto Self-Assembled Monolayers Deposited on Gold Electrodes Using Electrochemical Impedance Spectroscopy.

Understanding protein binding to biosensing surfaces is paramount to the design and performance of biosensing devices in fields such as point-of-care testing and bioanalytics. Here, we systematically demonstrated the use of electrical impedance spectroscopy (EIS) and equivalent circuit modeling for real-time tracking of chemisorption of IgG antibody to large-area circular gold electrodes (1.3 mm) functionalized with a self-assembled monolayer (SAM).

DNA extraction from bacteria using a gravity-driven microcapillary siphon.

Nucleic acid amplification tests (NAATs) are used in many applications ranging from human diagnostics to environmental monitoring. However, currently NAATs rely on access to bulky equipment and laboratory facilities. In particular, DNA extraction remains a key limiting step, with current methods depending on large devices and extensive manual pipetting.

Biorecognition-based electrochemical sensors for highly sensitive C-reactive protein detection: A review.

Highly sensitive C-reactive protein (hsCRP) is a widely recognized biomarker for inflammation and cardiovascular diseases and plays a critical role in early diagnosis, risk assessment, and treatment monitoring. The development of sensitive and selective techniques for hsCRP detection is of paramount importance for clinical diagnostics. Electrochemical sensors have emerged as promising alternatives to traditional methods, offering rapid, cost-effective, and portable solutions for hsCRP analysis.

Direct optical microalgal growth assessment using 'dip stick' microcapillary strips: A case study with Parachlorella kessleri.

Microalgal cultivation is increasingly important for industrial, agricultural, and environmental monitoring. Current methodologies for monitoring microalgal growth require periodical sampling, bulky laboratory equipment and specialized personnel. A novel 'dip-stick' micro-cultivation methodology based on fluorinated ethylene propylene microcapillary strips is herein proposed for real-time detection of microalgal growth.

Filamentous cyanobacteria growth assessment using fluorinated ethylene propylene microcapillaries.

Abstract: Filamentous cyanobacteria originate toxic harmful algal blooms (HABs) in aquatic ecosystems, severely impacting freshwater ecosystems and life. Despite being natural bloomers, these microorganisms are challenging to handle , due to the formation of aggregates with entangled filaments. Consequently, their precise growth dynamics, although vital to timely predict HABs, remains inaccessible.

Looping Flexible Fluoropolymer Microcapillary Film Extends Analysis Times for Vertical Microfluidic Blood Testing.

The microfluidic measurement of capillary flow can be used to evaluate the response of biological samples to stimulation, where distance and velocity are altered. Melt-extruded multi-bored microfluidic capillaries allow for high-throughput testing with low device cost, but simple devices may limit control over sample flow when compared to the more complex "lab-on-a-chip" devices produced using advanced microfluidic fabrication methods. Previously, we measured the dynamics of global haemostasis stimulated by thrombin by dipping straight vertical microcapillaries into blood, but only the most rapid response could be monitored, as flow slowed significantly within 30 s.

Advancements in Cortisol Detection: From Conventional Methods to Next-Generation Technologies for Enhanced Hormone Monitoring.

The hormone cortisol, released as the end-product of the hypothalamic-pituitary-adrenal (HPA) axis, has a well-characterized circadian rhythm that enables an allostatic response to external stressors. When the pattern of secretion is disrupted, cortisol levels are chronically elevated, contributing to diseases such as heart attacks, strokes, mental health disorders, and diabetes. The diagnosis of chronic stress and stress related disorders depends upon accurate measurement of cortisol levels; currently, it is quantified using mass spectroscopy or immunoassay, in specialized laboratories with trained personnel.

Time- and distance-resolved robotic imaging of fluid flow in vertical microfluidic strips: a new technique for quantitative, multiparameter measurement of global haemostasis.

Measuring the complex processes of blood coagulation, haemostasis and thrombosis that are central to cardiovascular health and disease typically requires a choice between high-resolution low-throughput laboratory assays, or simpler less quantitative tests. We propose combining mass-produced microfluidic devices with open-source robotic instrumentation to enable rapid development of affordable and portable, yet high-throughput and performance haematological testing. A time- and distance-resolved fluid flow analysis by Raspberry Pi imaging integrated with controlled sample addition and illumination, enabled simultaneous tracking of capillary rise in 120 individual capillaries (∼160, 200 or 270 μm internal diameter), in 12 parallel disposable devices.

Label-free 1D microfluidic dipstick counting of microbial colonies and bacteriophage plaques.

Counting viable bacterial cells and functional bacteriophage is fundamental to microbiology underpinning research, surveillance, biopharmaceuticals and diagnostics. Colony forming unit (CFU) and plaque forming unit (PFU) counting still requires slow and laborious solid culture on agar in Petri dishes or plates. Here, we show that dip-stick microfluidic strips can be used without growth indicator dye for rapid and simple CFU ml and PFU ml measurement.

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.

Antibody Surface Coverage Drives Matrix Interference in Microfluidic Capillary Immunoassays.

The performance of biosensors is often optimized in buffers, which brings inconsistencies during applications with biological samples. Current strategies for minimizing sample (matrix) interference are complex to automate and miniaturize, involving, e.g.

Microfluidic smartphone quantitation of Escherichia coli in synthetic urine.

In spite of the clinical need, there is a major gap in rapid diagnostics for identification and quantitation of E. coli and other pathogens, also regarded as the biggest bottleneck in the fight against the spread of antimicrobial resistant bacterial strains. This study reports for the first time an optical, smartphone-based microfluidic fluorescence sandwich immunoassay capable of quantifying E.

Transparent, Hydrophobic Fluorinated Ethylene Propylene Offers Rapid, Robust, and Irreversible Passive Adsorption of Diagnostic Antibodies for Sensitive Optical Biosensing.

Current literature data is scarce and somehow contradictory in respect to the suitability of "nonstick" fluoropolymer surfaces for immobilization of biomolecules. We have previously shown empirically that transparent Teflon fluorinated ethylene propylene (FEP) offers rapid and sensitive optical biosensing of clinically relevant biomarkers. This study shows for the first time a comprehensive experimental analysis of passive adsorption of diagnostic IgG antibodies on actual Teflon FEP microfluidic strips.

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.

Removal of antiretroviral drugs stavudine and zidovudine in water under UV and UV/HO 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 UV photolysis or UV/HO was investigated in a microcapillary film (MCF) photoreactor, using minimal water samples quantities. The UV quantum yield of zidovudine, (2.

Photodegradation and ecotoxicology of acyclovir in water under UV and UV/HO processes.

The photochemical and ecotoxicological fate of acyclovir (ACY) through UV direct photolysis and in the presence of hydroxyl radicals (UV/HO 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.

Covalent immobilisation of antibodies in Teflon-FEP microfluidic devices for the sensitive quantification of clinically relevant protein biomarkers.

This study reports for the first time the sensitive colorimetric and fluorescence detection of clinically relevant protein biomarkers by sandwich immunoassays using the covalent immobilisation of antibodies onto the fluoropolymer surface inside Teflon®-FEP microfluidic devices. Teflon®-FEP has outstanding optical transparency ideal for high-sensitivity colorimetric and fluorescence bioassays, however this thermoplastic is regarded as chemically inert and very hydrophobic. Covalent immobilisation can offer benefits over passive adsorption to plastic surfaces by allowing better control over antibody density, orientation and analyte binding capacity, and so we tested a range of different and novel covalent immobilisation strategies.

A critical insight into the development pipeline of microfluidic immunoassay devices for the sensitive quantitation of protein biomarkers at the point of care.

The latest clinical procedures for the timely and cost-effective diagnosis of chronic and acute clinical conditions, such as cardiovascular diseases, cancer, chronic respiratory diseases, diabetes or sepsis (i.e. the biggest causes of death worldwide), involve the quantitation of specific protein biomarkers released into the blood stream or other physiological fluids (e.

Lab on a stick: multi-analyte cellular assays in a microfluidic dipstick.

A new microfluidic concept for multi-analyte testing in a dipstick format is presented, termed "Lab-on-a-Stick", that combines the simplicity of dipstick tests with the high performance of microfluidic devices. Lab-on-a-stick tests are ideally suited to analysis of particulate samples such as mammalian or bacterial cells, and capable of performing multiple different parallel microfluidic assays when dipped into a single sample with results recorded optically. The utility of this new diagnostics format was demonstrated by performing three types of multiplex cellular assays that are challenging to perform in conventional dipsticks: 1) instantaneous ABO blood typing; 2) microbial identification; and 3) antibiotic minimum inhibitory (MIC) concentration measurement.

Investigation on the removal of the major cocaine metabolite (benzoylecgonine) in water matrices by UV254/H2O2 process by using a flow microcapillary film array photoreactor as an efficient experimental tool.

A microcapillary film reactor (MCF) was adopted to evaluate and compare the removal efficiency of benzoylecgonine (BE), an emerging micropollutant deriving from illicit drug abuse (cocaine), in different aqueous matrices: milliQ water, synthetic and real wastewater and surface water. The removal processes investigated were the direct photolysis with UV radiation at 254 nm, and the advanced oxidation process (AOP) with the same UV radiation and hydrogen peroxide. As a result of the microfluidics approach developed through an innovative experimental apparatus, full conversion of BE was reached within a few seconds or minutes of residence time in the MCF depending on the process conditions adopted.

Photo inactivation of virus particles in microfluidic capillary systems.

It has long been established that UVC light is a very effective method for inactivating pathogens in a fluid, yet the application of UVC irradiation to modern biotechnological processes is limited by the intrinsic short penetration distance of UVC light in optically dense protein solutions. This experimental and numerical study establishes that irradiating a fluid flowing continuously in a microfluidic capillary system, in which the diameter of the capillary is tuned to the depth of penetration of UVC light, uniquely treats the whole volume of the fluid to UVC light, resulting in fast and effective inactivation of pathogens, with particular focus to virus particles. This was demonstrated by inactivating human herpes simplex virus type-1 (HSV-1, a large enveloped virus) on a dense 10% fetal calf serum solution in a range of fluoropolymer capillary systems, including a 0.

Multiplexed femtomolar quantitation of human cytokines in a fluoropolymer microcapillary film.

Sensitive quantitation of multiple cytokines can provide important diagnostic information during infection, inflammation and immunopathology. In this study sensitive immunoassay detection of human cytokines IL-1β, IL-6, IL-12p70 and TNFα is shown for singleplex and multiplex formats using a novel miniaturized ELISA platform. The platform uses a disposable plastic multi-syringe aspirator (MSA) integrating 8 disposable fluoropolymer microfluidic test strips, each containing an array of ten 200 μm mean i.