Current advances in the detection of COVID-19 and evaluation of the humoral response

The new outbreak caused by coronavirus SARS-CoV-2 started at the end of 2019 and was declared a pandemic in March 2020. Since then, several diagnostic approaches have been re-adapted, and also improved from the previous detections of SARS and MERS coronavirus. The best strategy to handle this situation seems to rely on a triad of detection methods: (i) highly sensitive and specific techniques as the gold standard method, (ii) easier and faster point of care tests accessible for large population screening, and (iii) serology assays to complement the direct detection and to use for surveillance. In this study, we assessed the techniques and tests described in the literature, their advantages and disadvantages, and the interpretation of the results. Quantitative reverse transcription polymerase chain reaction (RT-qPCR) is undoubtedly the gold standard technique utilized not only for diagnostics, but also as a standard for comparison and validation of newer approaches. Other nucleic acid amplification methods have been shown to be adequate as point of care (POC) diagnostic tests with similar performance as RT-qPCR. The analysis of seroconversion with immunotests shows the complexity of the immune response to COVID-19. The detection of anti-SARS-CoV-2 antibodies can also help to detect previously infected asymptomatic individuals with negative RT-qPCR tests. Nevertheless, more controlled serology cohort studies should be performed as soon as possible to understand the immune response to SARS-CoV-2

High pressure synthesis of FePt nanoparticles with controlled morphology and Fe content

Magnetic nanoparticles (MNPs) are intensively researched due to their high potential in biomedicine, catalysis, and high density information storage. FePt NPs could be an alternative for commonly used magnetite NPs and the synthesis of FePt NPs is an active area of research. The challenge is to increase the Fe content and saturation magnetisation of FePt NPs so that they can be used in many practical applications. Fine tuning of synthetic methods is required in order to achieve the enhanced magnetic properties of FePt nanoparticles and novel methods are being sought. Herein, use of an autoclave is shown to increase the Fe content, crystallinity and the subsequent magnetic properties of FePt pseudo cube nanoparticles compared to those synthesised under atmospheric pressure. Decreasing the amount of oleic acid is also shown to increase the iron content and can lead to elongated FePt nanoparticles under normal pressure. Further application of nanoparticles synthesised in organic media often requires functionalisation or exchange of stabiliser chemicals. Greater demand for control over such functionalisation requires more information about nanoparticle–stabiliser chemical interactions. Infra-red studies indicate mono and bidentate coordination with oleic acid, however shifts of spectra show that the strength of the bidentate interactions weaken with increasing oleic acid amount

A Life Vest for Hudson Bay's Drifting Stewardship

Hudson Bay, as the world’s second-largest inland sea, is far from insignificant. Yet, the Hudson Bay bioregion barely registers on the radar of Canadian ocean management. When it does, it almost invariably appears under a project-specific approach or within the strict parameters of jurisdictional responsibilities. However, Inuit in Sanikiluaq, from their standpoint on the Belcher Islands, see the surrounding marine environment as being largely unrelated to political boundaries and jurisdictions. From their perspective, stewardship means ensuring the sustained health of Hudson Bay and its marine life. We advocate concrete steps to bring compartmentalized governmental processes in line with this more comprehensive definition of marine environmental stewardship. A twofold course of action is needed. The first step is to make joint, complementary use of scientific and Inuit knowledge to understand the cumulative, transboundary effects on this Arctic marine ecosystem of natural and human-induced changes. Second, collaboration is greatly needed to unify the present fragmented coastal and marine governance in the eastern Canadian Arctic. We therefore propose establishing a community-based monitoring and assessment network and a cooperative, inter-jurisdictional stewardship body. Such a collaborative effort could make tangible progress toward sound, ecosystem-based, integrated management of the Hudson Bay bioregion.La baie d’Hudson, soit la deuxième mer intérieure au monde de par sa superficie, est loin de revêtir peu d’importance. Pourtant, la biorégion de la baie d’Hudson est à peine captée sur le radar de la gestion canadienne des océans. Lorsqu’elle fait surface, c’est habituellement parce qu’elle fait l’objet d’un projet spécifique ou qu’elle se trouve à faire partie des paramètres stricts relevant de responsabilités juridictionnelles. Cela dit, du point de vue des Inuits de Sanikiluaq, sur les îles Belcher, l’environnement marin environnant n’a à peu près rien à voir avec les frontières et les juridictions politiques. D’après leur perspective, la gérance signifie qu’il faut donner lieu à un état durable pour la baie d’Hudson et sa vie marine. Nous nous prononçons en faveur de l’adoption de mesures concrètes afin que les processus gouvernementaux compartimentalisés cadrent mieux avec cette définition plus exhaustive de la gérance marine de l’environnement. Les mesures doivent se faire en deux temps. Dans un premier temps, il faut procéder à l’utilisation conjointe et complémentaire des connaissances des scientifiques et des Inuits pour en venir qu’à comprendre les effets cumulatifs et transfrontières sur cet écosystème marin de l’Arctique qui subit des changements à la fois provoqués par la nature et par l’être humain. Dans un deuxième temps, il y a lieu de collaborer pour unifier la gérance côtière et marine actuellement fragmentée dans l’est de l’Arctique canadien. Par conséquent, nous proposons l’établissement d’un réseau de surveillance et d’évaluation communautaire de même que d’un organisme coopératif et interjuridictionnel de gérance. Un tel effort de collaboration pourrait donner lieu à des progrès tangibles pour aboutir à la gestion solide et intégrée des écosystèmes de la biorégion de la baie d’Hudson

Quantifying the binding between proteins and open chromatin-like DNA sequences with gold nanorods

The binding of transcription factors to DNA is one of the main mechanisms in gene regulation. While transcription factors frequently bind to unwrapped long DNA sequences known as open chromatin structures, most bioassays that study protein–DNA binding rely on short oligonucleotide probes. In this work, we develop a gold nanorod-based colorimetric assay for the binding of transcription factors to DNA in long open chromatin-like structures. After the determination of the binding affinity and stoichiometry, we explored the effect of the probe length on the assay performance and compared it to other established techniques

Magnetic particle imaging: tracer development and the biomedical applications of a radiation-free, sensitive, and quantitative imaging modality

Magnetic particle imaging (MPI) is an emerging tracer-based modality that enables real-time three-dimensional imaging of the non-linear magnetisation produced by superparamagnetic iron oxide nanoparticles (SPIONs), in the presence of an external oscillating magnetic field. As a technique, it produces highly sensitive radiation-free tomographic images with absolute quantitation. Coupled with a high contrast, as well as zero signal attenuation at-depth, there are essentially no limitations to where can be imaged within the body. These characteristics enable various biomedical applications of clinical interest. In the opening sections of this review, the principles of image generation are introduced, along with a detailed comparison of the fundamental properties of this technique with other common imaging modalities. The main feature is a presentation on the up-to-date literature for the development of SPIONs tailored for improved imaging performance, and developments in the current and promising biomedical applications of this emerging technique, with a specific focus on theranostics, cell tracking and perfusion imaging. Finally, we will discuss recent progress in the clinical translation of MPI. As signal detection in MPI is almost entirely dependent on the properties of the SPION employed, this work emphasises the importance of tailoring the synthetic process to produce SPIONs demonstrating specific properties and how this impacts imaging in particular applications and MPI’s overall performance

Sensing of circulating cancer biomarkers with metal nanoparticles

The analysis of circulating cancer biomarkers, including cell-free and circulating tumor DNA, circulating tumor cells, microRNA and exosomes, holds promise in revolutionizing cancer diagnosis and prognosis using body fluid analysis, also known as liquid biopsy. To enable clinical application of these biomarkers, new analytical tools capable of detecting them in very low concentrations in complex sample matrixes are needed. Metal nanoparticles have emerged as extraordinary analytical scaffolds because of their unique optoelectronic properties and ease of functionalization. Hence, multiple analytical techniques have been developed based on these nanoparticles and their plasmonic properties. The aim of this review is to summarize and discuss the present development on the use of metal nanoparticles for the analysis of circulating cancer biomarkers. We examine how metal nanoparticles can be used as (1) analytical transducers in various sensing principles, such as aggregation induced colorimetric assays, plasmon resonance energy transfer, surface enhanced Raman spectroscopy, and refractive index sensing, and (2) signal amplification elements in surface plasmon resonance spectroscopy and electrochemical detection. We critically discuss the clinical relevance of each category of circulating biomarkers, followed by a thorough analysis of how these nanoparticle-based designs have overcome some of the main challenges that gold standard analytical techniques currently face, and what new directions the field may take in the future

Engineering hydrogel nanoparticles to enhance transdermal local anaesthetic delivery in human eyelid skin

Herein, we focused on developing the feasibility of nano-enabled local anaesthetic (LA) delivery to anaesthetise the full thickness of eyelid skin. For this purpose a temperature-responsive hydrogel poly(N-vinylcaprolactam-co-hyaluronic acid) (p(VCL-co-HA)) was prepared through aqueous emulsion polymerization with a Food and Drug Administration (FDA) approved p(VCL) and hyaluronic acid (HA) showing remarkably high LA drug loading capacity

Study of the Effect of Anisotropic Gold Nanoparticles on Plasmonic Coupling with a Photosensitizer for Antimicrobial Film

Development of antimicrobial surfaces for sterilization is much needed to avoid the spreading of drug resistant bacteria. Light can activate antimicrobial surfaces by an interaction between nanoparticles and a photosensitizer dye to produce a steady and efficient killing of bacteria. The film studied in this work contains gold nanorods (AuNRs) of 32 nm length and 16 nm diameter and gold nanostars (AuNSs) of 50 nm of diameter, in combination with crystal violet (CV) dye. The surface plasmon resonance (SPR) of the nanoparticles used in the film was mathematically simulated and characterized to understand different SPR between the particles. Their effects on plasmonic coupling with the dye, and thus the production of reactive oxygen species (ROS) and consequently the activity of the film against bacteria, were studied. The films showed great antimicrobial activity against Gram-negative bacteria (E. coli) in 4 h of light exposure; when modified with AuNSs, it could kill E. coli with 5 orders of magnitude (5-log), and the one modified with AuNRs could kill with 4 order of magnitude (4-log), while maintaining partial activity against Gram-positive bacteria (S. aureus), i.e. being able to kill with 2.5 orders of magnitude by the film containing AuNSs and 3 orders of magnitude by those containing AuNRs. The differential response of Gram-negative and Gram-positive bacteria to the ROS generated by the films would allow a more targeted approach for specific bacterial species, for example, surfaces of bedpans or common contact surfaces (handles, handrails, etc.) that are contaminated principally by Gram-negative or Gram-positive bacteria, respectively