Physicochemical study of natural fractionated biocolloid by asymmetric flow field-flow fractionation in tandem with various complementary techniques using biologically synthesized silver nanocomposites

Field-Flow Fractionation in Molecular Biology and Biotechnology

Field-flow fractionation (FFF) is a family of single-phase separative techniques exploited to gently separate and characterize nano- and microsystems in suspension. These techniques cover an extremely wide dynamic range and are able to separate analytes in an interval between a few nm to 100 µm size-wise (over 15 orders of magnitude mass-wise). They are flexible in terms of mobile phase and can separate the analytes in native conditions, preserving their original structures/properties as much as possible. Molecular biology is the branch of biology that studies the molecular basis of biological activity, while biotechnology deals with the technological applications of biology. The areas where biotechnologies are required include industrial, agri-food, environmental, and pharmaceutical. Many species of biological interest belong to the operational range of FFF techniques, and their application to the analysis of such samples has steadily grown in the last 30 years. This work aims to summarize the main features, milestones, and results provided by the application of FFF in the field of molecular biology and biotechnology, with a focus on the years from 2000 to 2022. After a theoretical background overview of FFF and its methodologies, the results are reported based on the nature of the samples analyzed.

The Size-Dependent Effects of Silver Nanoparticles on Germination, Early Seedling Development and Polar Metabolite Profile of Wheat (Triticum aestivum L.)

The phytotoxicity of silver nanoparticles (Ag NPs) to plant seeds germination and seedlings development depends on nanoparticles properties and concentration, as well as plant species and stress tolerance degrees. In the present study, the effect of citrate-stabilized spherical Ag NPs (20 mg/L) in sizes of 10, 20, 40, 60, and 100 nm, on wheat grain germination, early seedlings development, and polar metabolite profile in 3-day-old seedlings were analyzed. Ag NPs, regardless of their sizes, did not affect the germination of wheat grains. However, the smaller nanoparticles (10 and 20 nm in size) decreased the growth of seedling roots. Although the concentrations of total polar metabolites in roots, coleoptile, and endosperm of seedlings were not affected by Ag NPs, significant re-arrangements of carbohydrates profiles in seedlings were noted. In roots and coleoptile of 3-day-old seedlings, the concentration of sucrose increased, which was accompanied by a decrease in glucose and fructose. The concentrations of most other polar metabolites (amino acids, organic acids, and phosphate) were not affected by Ag NPs. Thus, an unknown signal is released by small-sized Ag NPs that triggers affection of sugars metabolism and/or distribution.

Label-Free Isolation of Exosomes Using Microfluidic Technologies

Exosomes are cell-derived structures packaged with lipids, proteins, and nucleic acids. They exist in diverse bodily fluids and are involved in physiological and pathological processes. Although their potential for clinical application as diagnostic and therapeutic tools has been revealed, a huge bottleneck impeding the development of applications in the rapidly burgeoning field of exosome research is an inability to efficiently isolate pure exosomes from other unwanted components present in bodily fluids. To date, several approaches have been proposed and investigated for exosome separation, with the leading candidate being microfluidic technology due to its relative simplicity, cost-effectiveness, precise and fast processing at the microscale, and amenability to automation. Notably, avoiding the need for exosome labeling represents a significant advance in terms of process simplicity, time, and cost as well as protecting the biological activities of exosomes. Despite the exciting progress in microfluidic strategies for exosome isolation and the countless benefits of label-free approaches for clinical applications, current microfluidic platforms for isolation of exosomes are still facing a series of problems and challenges that prevent their use for clinical sample processing. This review focuses on the recent microfluidic platforms developed for label-free isolation of exosomes including those based on sieving, deterministic lateral displacement, field flow, and pinched flow fractionation as well as viscoelastic, acoustic, inertial, electrical, and centrifugal forces. Further, we discuss advantages and disadvantages of these strategies with highlights of current challenges and outlook of label-free microfluidics toward the clinical utility of exosomes.

The Study on Molecular Profile Changes of Pathogens via Zinc Nanocomposites Immobilization Approach

The most critical group of all includes multidrug resistant bacteria that pose a particular threat in hospitals, as they can cause severe and often deadly infections. Modern medicine still faces the difficult task of developing new agents for the effective control of bacterial-based diseases. The targeted administration of nanoparticles can enhance the efficiency of conventional pharmaceutical agents. However, the interpretation of interfaces' interactions between nanoparticles and biological systems still remains a challenge for researchers. In fact, the current research presents a strategy for using ZnO NPs immobilization with ampicillin and tetracycline. Firstly, the study provides the mechanism of the ampicillin and tetracycline binding on the surface of ZnO NPs. Secondly, it examines the effect of non-immobilized ZnO NPs, immobilized with ampicillin (ZnONPs/AMP) and tetracycline (ZnONPs/TET), on the cells' metabolism and morphology, based on the protein and lipid profiles. A sorption kinetics study showed that the antibiotics binding on the surface of ZnONPs depend on their structure. The efficiency of the process was definitely higher in the case of ampicillin. In addition, flow cytometry results showed that immobilized nanoparticles present a different mechanism of action. Moreover, according to the MALDI approach, the antibacterial activity mechanism of the investigated ZnO complexes is mainly based on the destruction of cell membrane integrity by lipids and proteins, which is necessary for proper cell function. Additionally, it was noticed that some of the identified changes indicate the activation of defense mechanisms by cells, leading to a decrease in the permeability of a cell's external barriers or the synthesis of repair proteins.

Use of Lactobacillus paracasei isolated from whey for silver nanocomposite synthesis: Antiradical and antimicrobial properties against selected pathogens

The present research emphasizes the use of safe, inexpensive, and available whey using Lactobacillus paracasei as a source in silver nanocomposite synthesis as an alternative bioactive agent for dairy and biomedical applications. Through the multiinstrumental approach used in this study based on spectroscopic and microscopic methods as well as spectrometric techniques, the characterization and evaluation of silver composites and their antimicrobial and antiradical properties were enabled. Synthesized silver nanocomposites have been found in form of nanocrystals, naturally coated by an organic surface with high antimicrobial and antiradical properties. Furthermore, this work also presents an innovative approach regarding the organic surface (naturally secreted by the bacteria isolated from whey) of the core of nanoparticles, which has already been explored and therefore is starting to supplement the scientific approach concerning biologically synthesized nanoparticles. This work also presents a general frame on the resistance subject by performing the trial interaction of commercially available antibiotics (kanamycin and ampicillin) with new bioactive compounds that can create novel knowledge on complementing their action. Moreover, synthesized silver nanocomposites have shown great antioxidant and antimicrobial effects against various foodborne pathogens from dairy products and drug resistance pathogens found in the medical area to rank on the top of mortality rate.

Zinc Oxide Nanocomposites-Extracellular Synthesis, Physicochemical Characterization and Antibacterial Potential

This research presents, for the first time, the potential of the Lactobacillus paracasei LC20 isolated from sweet whey as a novel, effective and accessible source for post-cultured ZnO nanocomposites synthesis. The obtained nanocomposites were subjected to comprehensive characterization by a broad spectrum of instrumental techniques. Results of spectroscopic and microscopic analysis confirmed the hexagonal crystalline structure of ZnO in the nanometer size. The dispersion stability of the obtained nanocomposites was determined based on the zeta potential (ZP) measurements-the average ZP value was found to be -29.15 ± 1.05 mV in the 7-9 pH range. The ZnO nanocomposites (NCs) demonstrated thermal stability up to 130 °C based on the results of thermogravimetric TGA/DTG) analysis. The organic deposit on the nanoparticle surface was recorded by spectroscopic analysis in the infrared range (FT-IR). Results of the spectrometric study exhibited nanostructure-assisted laser desorption/ionization effects and also pointed out the presence of organic deposits and, what is more, allowed us to identify the specific amino acids and peptides present on the ZnO NCs surfaces. In this context, mass spectrometry (MS) data confirmed the nano-ZnO formation mechanism. Moreover, fluorescence data showed an increase in fluorescence signal in the presence of nanocomposites designed for potential use as, e.g., biosensors. Despite ZnO NCs' luminescent properties, they can also act as promising antiseptic agents against clinically relevant pathogens. Therefore, a pilot study on the antibacterial activity of biologically synthesized ZnO NCs was carried out against four strains (Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa) by using MIC (minimal inhibitory concentration). Additionally, the colony forming units (CFU) assay was performed and quantified for all bacterial cells as the percentage of viable cells in comparison to a control sample (untreated culture) The nanocomposites were effective among three pathogens with MIC values in the range of 86.25-172.5 μg/mL and showed potential as a new type of, e.g., medical path or ointment formulation.

The Influence of Different Forms of Silver on Selected Pathogenic Bacteria

The application of silver nanoparticles as an antibacterial agent is becoming more common. Unfortunately, their effect on microorganisms is still not fully understood. Therefore, this paper attempts to investigate the influence of silver ions, biologically synthesized silver nanoparticles and nanoparticles functionalized with antibiotics on molecular bacteria profiles. The initial stage of research was aimed at the mechanism determination involved in antibiotics sorption onto nanoparticles' surface. For this purpose, the kinetics study was performed. Next, the functionalized formulations were characterized by Fourier transform infrared spectroscopy (FT-IR), dynamic light scattering (DLS) and a zeta potential study. The results reveal that functionalization is a complex process, but does not significantly affect the stability of biocolloids. Furthermore, the antimicrobial assays, in most cases, have shown no increases in antibacterial activity after nanoparticle functionalization, which suggests that the functionalization process does not always generate the improved antimicrobial effect. Finally, the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) technique was employed to characterize the changes in the molecular profile of bacteria treated with various antibacterial agents. The recorded spectra proved many differences in bacterial lipids and proteins profiles compared to untreated cells. In addition, the statistical analysis of recorded spectra revealed the strain-dependent nature of stress factors on the molecular profile of microorganisms.

Complementarity of Matrix- and Nanostructure-Assisted Laser Desorption/Ionization Approaches

In recent years, matrix-assisted laser desorption/ionization (MALDI) has become the main tool for the study of biological macromolecules, such as protein nano-machines, especially in the determination of their molecular masses, structure, and post-translational modifications. A key role in the classical process of desorption and ionization of the sample is played by a matrix, usually a low-molecular weight weak organic acid. Unfortunately, the interpretation of mass spectra in the mass range of below m/z 500 is difficult, and hence the analysis of low molecular weight compounds in a matrix-assisted system is an analytical challenge. Replacing the classical matrix with nanomaterials, e.g., silver nanoparticles, allows improvement of the selectivity and sensitivity of spectrometric measurement of biologically important small molecules. Nowadays, the nanostructure-assisted laser desorption/ionization (NALDI) approach complements the classic MALDI in the field of modern bioanalytics. In particular, the aim of this work is to review the recent advances in MALDI and NALDI approaches.