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

This study reports for the first time sensitive colorimetric and fluorescence detection of clinically relevant protein biomarkers by sandwich immunoassays using 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. We first functionalised the inner surface of a 10-bore, 200 µm internal diameter FEP microcapillary film with high-molecular weight polyvinyl alcohol (PVOH) without changing the outstanding optical transparency of the device delivered by the matched refractive index of FEP and water. Glutaraldehyde immobilisation was compared with use of photoactivated linkers and NHS-ester crosslinkers for covalently immobilising capture antibodies onto PVOH. Three clinically relevant sandwich ELISAs were tested, against the cytokine IL-1ß, the myocardial infarct marker cardiac troponin I (cTnI), and the chronic heart failure marker brain natriuretic peptide (BNP). Overall, glutaraldehyde immobilisation was effective for BNP assays, but yielded unacceptable background for IL-1ß and cTnI assays caused by direct binding of biotinylated detection antibody to the modified PVOH surface. We found NHS-ester groups reacted with APTES-treated PVOH coated fluoropolymer. This facilitated a novel method for capture antibody immobilisation onto fluoropolymer devices using a bifunctional NHS-maleimide crosslinker. The density of covalently immobilised capture antibodies achieved using PVOH/APTES/NHS/Maleimide approached levels seen with passive adsorption, and sensitive and quantitative assay performance was achieved using this method. Overall, PVOH coating provided an excellent surface for controlled covalent antibody immobilisation onto Teflon®-FEP for performing high-sensitivity immunoassays

Leaving no aspect of sustainability behind: A framework for designing sustainable energy interventions applied to refugee camps

The issues of forced displacement and energy for sustainable development are convergent: an estimated 90% of displaced people globally have no access to electricity, while 85% of refugees are hosted in developing countries. However, few tools to plan and design sustainable energy access interventions have been transposed to displacement settings. This paper presents a novel framework for the holistic planning of energy projects which considers both sustainability aspects and the specificities of displacement settings. The framework is the result of a review of literature which aimed to define a “sustainable energy intervention” in displacement contexts and an assessment of relevant planning tools against this definition. The framework includes the use of an energy delivery model toolkit, an inclusive design approach, an assessment of the desired impacts, energy system modelling, business model design, and an assessment of economic viability. We apply the framework in the design of a solar mini grid of Holl Holl refugee camp in Djibouti, in which a sustainable intervention and business model are proposed that could be compatible with the local conditions. We highlight issues that arise from the humanitarian sector status quo and propose that this framework could help to enhance sustainable energy practices in the humanitarian and development sectors

The OptoMEA platform: a new tool combining local chemical stimulation with distributed multi-electrode array recordings

We present a novel OptoMEA platform that combines multisite electrical recording with local chemical stimulation. Applying UV light pulses through an array of optical fibres aligned to transparent indium-tin oxide electrodes of an MEA biochip leads to local compound uncaging (e.g. glutamate), thereby stimulating only the tissue/cells around the electrode vicinity. Experimental results obtained using the OptoMEA platform demonstrate its capability to uncage chemical compounds and to locally stimulate neuronal networks, thus providing a significant improvement in spatial control of chemical stimulation. It is expected that this methodology will be useful in facilitating studies of neuronal network systems, and may also find applications in drug screening

OptoMEA: a new tool for combining local optical activation of compounds with distributed MEA recordings

Since their introduction, Micro-Electrode Arrays (MEAs) have been exploited as devices providing distributed information about learning, memory and information processing in a cultured neuronal network, thus changing the field of view from single cell level (glass pipettes) to the scale of the complex network. MEAs represent a growing technology for the study of the functional activity of neuronal networks providing the possibility to gain information about the spatio-temporal dynamics of the network and to allow recordings of electrical activity over periods of time not compatible with conventional electrodes at several sites in parallel. More recently, according to the trend aimed at the reduction of animal tests, MEAs have been exploited as in vitro biosensors to monitor both acute and chronic effects of drugs on neuronal networks in physiological or pathophysiological conditions. On the contrary, the presence of stimulus artefacts and the poorly controlled spread of electrical stimuli in the culture medium limit the applicability of MEAs for neuronal stimulation. Although the problem of artefacts has been recently solved using blanking circuits, the problem of spreading of electrical signals is inherent to the use of electrical stimulations in a conductive volume. Moreover, because neurons are naturally interconnected in complex networks electrical stimuli applied to a region of the network may activate neurons of that region and also fibres of passage coming from neurons of other regions. To overcome these limitations, in addition to electrophysiological techniques, optical methods for the stimulation of neurons have been used for relatively a long time, i.e. by caged compound activation. Here we present the new OptoMEA tool where local light stimulations were obtained switching caged glutamate in the active form by UV light pulses using optical fibres exactly aligned at the MEA electrodes. This tool allows us to activate the network or to deliver other active compounds in specific regions of the network and to monitor their effects on the overall network functioning. This methodology may turn out to be extremely useful for testing the ability of drugs to affect neuronal properties as well as alterations in inter- and intra-neuronal communication

Study protocol for a two-site clinical trial to validate a smartphone-based artificial intelligence classifier identifying cervical precancer and cancer in HPV-positive women in Cameroon.

INTRODUCTION: Cervical cancer remains a major public health challenge in low- and middle-income countries (LMICs) due to financial and logistical issues. WHO recommendation for cervical cancer screening in LMICs includes HPV testing as primary screening followed by visual inspection with acetic acid (VIA) and treatment. However, VIA is a subjective procedure dependent on the healthcare provider's experience. Its accuracy can be improved by computer-aided detection techniques. Our aim is to assess the performance of a smartphone-based Automated VIA Classifier (AVC) relying on Artificial Intelligence to discriminate precancerous and cancerous lesions from normal cervical tissue. METHODS: The AVC study will be nested in an ongoing cervical cancer screening program called "3T-study" (for Test, Triage and Treat), including HPV self-sampling followed by VIA triage and treatment if needed. After application of acetic acid on the cervix, precancerous and cancerous cells whiten more rapidly than non-cancerous ones and their whiteness persists stronger overtime. The AVC relies on this key feature to determine whether the cervix is suspect for precancer or cancer. In order to train and validate the AVC, 6000 women aged 30 to 49 years meeting the inclusion criteria will be recruited on a voluntary basis, with an estimated 100 CIN2+, calculated using a confidence level of 95% and an estimated sensitivity of 90% +/-7% precision on either side. Diagnostic test performance of AVC test and two current standard tests (VIA and cytology) used routinely for triage will be evaluated and compared. Histopathological examination will serve as reference standard. Participants' and providers' acceptability of the technology will also be assessed. The study protocol was registered under ClinicalTrials.gov (number NCT04859530). EXPECTED RESULTS: The study will determine whether AVC test can be an effective method for cervical cancer screening in LMICs

Circular and net-zero opportunities in the management of electronic waste in low- and middle-income countries: the example of Ghana

Low- and middle-income countries suffer from excessive accumulation of electronic waste (e-waste), partly owing to a lack of recycling infrastructure and relevant policy frameworks, which can lead to significant toxic exposure of the surrounding populations and the environment. Using Ghana as an example, the complexity of the network of actors involved in the e-waste management value chain is discussed from this perspective. More specifically, this study aims to characterize the structure of the e-waste sector in Accra, Ghana, and investigate approaches to render a more feasible circular economy. An alternative framework for gold recycling is proposed. Emerging environmentally friendly gold recycling technologies are discussed to support the feasibility of this approach. Overall, this would enable circular management of e-waste and improve the health of the informal sector. Based on this analysis, the recovery of gold could ideally generate 450 million USD/year, while significantly reducing the environmental footprint associated with the life cycle of gold by extending its lifetime. Examining the global warming potential (GWP) linked to the production of key materials in e-waste shows that gold exhibits the most significant environmental impact, accounting for 86% of the total GWP of the studied e-waste sample

A synthetic membrane protein in tethered lipid bilayers for immunosensing in whole blood

Tethered lipid bilayers, containing a transmembrane synthetic ligand-gated ion channel (SLIC), have been formed on gold surfaces. The SLIC was designed as a highly selective receptor and reporter protein to detect antibodies in whole blood, which are of importance in malaria diagnosis. The specific binding of the antibody to the sensor surface was monitored on-line with label-free surface-sensitive techniques either optically by surface plasmon resonance in whole blood or electrically by measuring the channel activity of SLIC in blood serum. We demonstrate the feasibility of a highly sensitive and easily applicable whole blood biosensor on the basis of simple commercially available components. The sensor might find applications in the field of infectious diseases such as point-of-care diagnostics of malaria, high content quality control of blood samples of donors, or monitoring the efficacy of vaccination. (C) 2009 Elsevier Inc. All rights reserved

The status of refrigeration solutions for last mile vaccine delivery in low-income settings

Recommendations for storage of most vaccines imply a continuous exposure to a temperature range between 0 degrees C and 10 degrees C, from the production to the administration to beneficiaries. According to the World Health Organization, more than 50% of vaccines are wasted around the world. Discontinuities of the cold chain in low-income settings where electricity is scarce contributes to this wastage. Recently, several advances have been made in cooling technologies to store and transport vaccines. This paper presents an overview of refrigeration technologies based on scientific publications, industry white papers and other grey literature. With a focus on vaccine transport, we briefly describe each refrigeration method, its best performing available devices as well as the outstanding research challenges in order to further improve its performance.(c) 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/)