Multiparametric Biosensors for Characterizing Extracellular Vesicle Subpopulations

Exosome-Based Sensor: A Landmark of the Precision Cancer Diagnostic Era

Extracellular vesicles are nanoscale vesicles released by a diversity of cells that mediate intercellular communication by transporting an array of biomolecules. They are gaining increasing attention in cancer research due to their ability to carry specific biomarkers. This characteristic makes them potentially useful for highly sensitive, noninvasive diagnostic procedures and more precise prognostic assessments. Consequently, EVs are emerging as a transformative tool in cancer treatment, facilitating early detection and personalized medicine. Despite significant progress, clinical implementation is hindered by challenges in EV isolation, purification, and characterization. However, developing advanced biosensor technologies offers promising solutions to these obstacles. This review highlights recent progress in biosensors for EV detection and analysis, focusing on various sensing modalities including optical, electrochemical, microfluidic, nanomechanical, and biological sensors. We also explore techniques for EV isolation, characterization, and analysis, such as electron microscopy, atomic force microscopy, nanoparticle tracking analysis, and single-particle analysis. Furthermore, the review critically assesses the challenges associated with EV detection and put forward future directions, aiming to usher in a cutting-edge era of precision medicine through advanced, sensor-based, noninvasive early cancer diagnosis by detecting EV-carried biomarkers.

Aptamer selection via versatile microfluidic platforms and their diverse applications

Aptamers are synthetic oligonucleotides that bind with high affinity and specificity to various targets, making them invaluable for diagnostics, therapeutics, and biosensing. Microfluidic platforms can improve the efficiency and scalability of aptamer selection, especially through advancements in systematic evolution of ligands by exponential enrichment (SELEX) methods. Microfluidic SELEX methods are less time-consuming and labor-intensive and include critical steps like library preparation, binding, partitioning, and amplification. This review examines the contributions of microfluidic technology to SELEX-based aptamer identification, with alternative methods like conditional SELEX, in vivo-like SELEX and Non-SELEX for selecting aptamers and also discusses critical SELEX steps over the past decade. This work also examined the integrated microfluidic systems for SELEX, highlighting innovations such as conditional SELEX and in vivo-like SELEX. These advancements provide potential solutions to existing challenges in aptamer selection using conventional SELEX, especially concerning biological samples. A trend toward non-SELEX methods was also reviewed and discussed, wherein nucleic acid amplification was eliminated to improve aptamer selection. Microfluidic platforms have demonstrated versatility not only in aptamer selection but also in various detection applications; they allow for precise control of liquid flow and have been essential in the advancement of therapeutic aptamers, facilitating accurate screening, enhancing drug delivery systems, and enabling targeted therapeutic interventions. Although advances in microfluidic technology are expected to enhance aptamer-based diagnostics, therapeutics, and biosensing, challenges still persist, especially in up-scaling microfluidic systems for various clinical applications. The advantages and limitations of integrating microfluidic platforms with aptamer development are further addressed, emphasizing areas for future research. We also present a perspective on the future of microfluidic systems and aptamer technologies, highlighting their increasing significance in healthcare and diagnostics.

A comprehensive review on recent advances in exosome isolation and characterization: Toward clinical applications

Exosomes are small, round vesicles in the 30 and 120 nm diameter range released by all living cell types. Exosomes play many essential functions in intercellular communication and tissue crosstalk in the human body. They can potentially be used as strong biomarkers and therapeutic agents for early diagnosis, therapy response, and prognosis of different diseases. The main requirements for exosomal large-scale clinical practice application are rapid, easy, high-yield, high purity, characterization, safety, low cost, and therapeutic efficacy. Depending on the sample types, environmental insults, and exosome quantity, exosomes can be isolated from various sources, including body fluids, solid tissues, and cell culture medium using different procedures. This study comprehensively analyzed the current research progress in exosome isolation and characterization strategies along with their advantages and disadvantages. The provided information will make it easier to select exosome separation methods based on the types of biological samples available, and it will facilitate the use of exosomes in translational and clinical research, particularly in cancer. Lay abstract Exosomes have recently received much attention due to their potential to function as biomarkers and novel therapeutic agents for early diagnosis, therapeutic response, and prognosis in various diseases. This review summarizes many approaches for isolating and characterizing exosomes, focusing on developing technologies, and provides an in-depth comparison and analysis of each method, including its principles, advantages, and limitations.

Multiparametric modulation of magnetic transduction for biomolecular sensing in liquids

The recent COVID19 pandemic has remarkably boosted the research on in vitro diagnosis assays to detect biomarkers in biological fluids. Specificity and sensitivity are mandatory for diagnostic kits aiming to reach clinical stages. Whilst the modulation of sensitivity can significantly improve the detection of biomarkers in liquids, this has been scarcely explored. Here, we report on the proof of concept and parametrization of a novel biosensing methodology based on the changes of AC magnetic hysteresis areas observed for magnetic nanoparticles following biomolecular recognition in liquids. Several parameters are shown to significantly modulate the transducing capacity of magnetic nanoparticles to detect analytes dispersed in saline buffer at concentrations of clinical relevance. Magnetic nanoparticles were bio-conjugated with an engineered recognition peptide as a receptor. Analytes are engineered tetratricopeptide binding domains fused to the fluorescent protein whose dimerization state allows mono- or divalent variants. Our results unveil that the number of receptors per particle, analyte valency and concentration, nanoparticle composition and concentration, and field conditions play a key role in the formation of assemblies driven by biomolecular recognition. Consequently, all these parameters modulate the nanoparticle transduction capacity. Our study provides essential insights into the potential of AC magnetometry for customizing biomarker detection in liquids.

Identification of potential novel proteomic markers of Leishmania spp.-derived exosomes

Introduction

Extracellular vesicles (EVs) are heterogenous cell-derived membrane-bound structures which can be subdivided into three distinct classes according to distinct morphological characteristics, cellular origins, and functions. Small EVs, or exosomes, can be produced by the protozoan parasite Leishmania through the evolutionarily conserved ESCRT pathway, and act as effectors of virulence and drivers of pathogenesis within mammalian hosts. Techniques for the identification of EVs of non-mammalian origin, however, remain inaccurate in comparison to their well-characterized mammalian counterparts. Thus, we still lack reliable and specific markers for Leishmania-derived exosomes, which poses a significant challenge to the field.

Methods

Herein, we utilized serial differential ultracentrifugation to separate Leishmania-derived EV populations into three distinct fractions. Nanoparticle tracking analysis and transmission electron microscopy were used to validate their morphological characteristics, and bioinformatic analysis of LC-MS/MS proteomics corroborated cellular origins and function.

Discussion

Proteomic data indicated potential novel proteic markers of Leishmania-derived exosomes, including proteins involved in endosomal machinery and the ESCRT pathway, as well as the parasitic phosphatase PRL-1. Further investigation is required to determine the specificity and sensitivity of these markers.