Quantification of Desiccated Extracellular Vesicles by Quartz Crystal Microbalance

Quantification of Enzymatic Biofilm Removal Using the Sauerbrey Equation: Application to the Case of Pseudomonas protegens

A methodology for the quantitative analysis of enzymatic removal of biofilms (BF) was developed, based on a quartz crystal microbalance (QCM) under stationary conditions. This was applied to the case of Pseudomonas protegens (PP) BFs, through a series of five enzymes, whose removal activity was screened using the presented methodology. The procedure is based on the following: when BFs can be modeled as rigid materials, QCM can be used as a balance under stationary conditions for determining the BFs mass reduction by enzymatic removal. For considering a BF as a rigid model, energy dissipation effects, associated with viscoelastic properties of the BF, must be negligible. Hence, a QCM system with detection of dissipation (referred to as QCM with dissipation) was used for evaluating the energy losses, which, in fact, resulted in negligible energy losses in the case of dehydrated PP BFs, validating the application of the Sauerbrey equation for the change of mass calculations. The stationary methodology reduces operating times and simplifies data analysis in comparison to dynamic approaches based on flow setups, which requires the incorporation of dissipation effects due to the liquid media. By carrying out QCM, glycosidase-type enzymes showed BF removal higher than 80% at enzyme concentration 50 ppm, reaching removal over 90% in the cases of amylase and cellulase/xylanase enzymes. The highest removal percentage produced a reduction from about 15 to 1 μg in the BF mass. Amylase enzyme was tested from below 50 to 1 ppm, reaching around 60% of removal at 1 ppm. The obtained results were supported by other instrumental techniques such as Raman spectroscopy, attenuated total reflection Fourier transform infrared spectroscopy, atomic force microscopy, high performance anion exchange chromatography, thermogravimetric analysis, and differential scanning calorimetry. The removal quantifications obtained with QCM were compared with those obtained by well-established screening techniques (UV-vis spectrophotometry using crystal violet and agar diffusion test). The proposed methodology expands the possibility of using a quartz microbalance to perform enzymatic activity screening.

Filtration-based technologies for isolation, purification and analysis of extracellular vesicles

The involvement of extracellular vesicles (EVs) in cellular communication with multifactorial and multifaceted biological activity has generated significant interest, highlighting their potential diagnostic and therapeutic applications. EVs are found in nearly all biological fluids creating a broad spectrum of where potential disease markers can be found for liquid biopsy development and what subtypes can be used for treatment of diseases. Complexity of biological fluids has generated a variety of different approaches for EV isolation and identification that may in one way or another be most optimal for research studies or clinical use. Each approach has its own advantages and disadvantages, significance of which can be evaluated depending on the end goal of the study. One of the methods is based on filtration which has received attention in the past years due its versatility, low cost and other advantages. Introduction of different approaches for EV capture and analysis that are based on filtration gave rise to new subcategories of filtration techniques which are presented in this overview. Miniaturization and combination of filtration-based approaches with microfluidics is also highlighted due its future prospects in healthcare, especially point-of-need technologies.

Selective Detection of Erythrocytes with QCMs-ABO Blood Group Typing

Blood transfusion, as well as organ transplantation, is only possible after prior blood group (BG) typing and crossmatching. The most important blood group system is that of Landsteiner's ABO classification based on antigen presence on the erythrocyte surfaces. A mass sensitive QCM (quartz crystal microbalance) sensor for BG typing has been developed by utilizing molecular imprinting technology. Polyvinylpyrrolidone (crosslinked with N,N-methylenebisacrylamide) is a favorable coating that was imprinted with erythrocytes of different blood groups. In total, 10 MHz quartz sheets with two resonators, one for MIP (molecularly imprinted polymer) and the other for NIP (non-imprinted polymer) were fabricated and later used for mass-sensitive measurements. The structure of erythrocyte imprints resembles a donut, as identified by AFM (atomic force microscope). All the erythrocytes of the ABO system were chosen as templates and the responses to these selective coatings were evaluated against all blood groups. Each blood group can be characterized by the pattern of responses in an unambiguous way. The results for blood group O are remarkable given that all types of erythrocytes give nearly the same result. This can be easily understood as blood group O does not possess neither antigen A nor antigen B. The responses can be roughly related to the number of respective antigens on the erythrocyte surface. The imprints generate hollows, which are used for reversible recognition of the erythrocytes. This procedure is based on molecular recognition (based on supramolecular strategies), which results from size, shape and enthalpic interactions between host and guest molecules.

COVID-19 and Pregnancy: An Updated Review about Evidence-Based Therapeutic Strategies

The COVID-19 pandemic posed a significant challenge for clinicians in managing pregnant women, who were at high risk of virus transmission and severe illness. While the WHO declared in May 2023 that COVID-19 is no longer a public health emergency, it emphasized that it remains a global health threat. Despite the success of vaccines, the possibility of new pandemic waves due to viral mutations should be considered. Ongoing assessment of the safety and effectiveness of pharmacological therapies is crucial in clinical practice. This narrative review summarizes the evidence-based therapeutic strategies for pregnant women with COVID-19, considering over three years of pandemic experience. The review discusses the safety and effectiveness of various drug regimens (antivirals, anticoagulants, corticosteroids, immunoglobulins, monoclonal antibodies, and therapeutic gases) and procedures (prone positioning and extracorporeal membrane oxygenation). Drugs with contraindications, inefficacy during pregnancy, or unknown adverse effects were excluded from our evaluation. The aim is to provide healthcare professionals with a comprehensive guide for managing pregnant women with COVID-19 based on lessons learned from the pandemic outbreak.

Clinical Application of Small Extracellular Vesicles in Gynecologic Malignancy Treatments

Small extracellular vesicles (sEVs) are the key mediators of intercellular communication. They have the potential for clinical use as diagnostic or therapeutic biomarkers and have been explored as vectors for drug delivery. Identification of reliable and noninvasive biomarkers, such as sEVs, is important for early diagnosis and precise treatment of gynecologic diseases to improve patient prognosis. Previous reviews have summarized routine sEVs isolation and identification methods; however, novel and unconventional methods have not been comprehensively described. This review summarizes a convenient method of isolating sEVs from body fluids and liquid biopsy-related sEV markers for early, minimally invasive diagnosis of gynecologic diseases. In addition, the characteristics of sEVs as drug carriers and in precision treatment and drug resistance are introduced, providing a strong foundation for identifying novel and potential therapeutic targets for sEV therapy. We propose potential directions for further research on the applications of sEVs in the diagnosis and treatment of gynecologic diseases.

Biosensors in 2022

Sixty years have passed since Clark and Lyons proposed the concept of using glucose enzyme electrodes to monitor the oxygen that is consumed during an enzyme-catalyzed reaction [...].