Surface-modified magnetite nanoparticles affect lysozyme amyloid fibrillization.

BACKGROUND: The surface of nanoparticles (NPs) is an important factor affecting the process of poly/peptides' amyloid aggregation. We have investigated the in vitro effect of trisodium citrate (TC), gum arabic (GA) and citric acid (CA) surface-modified magnetite nanoparticles (COAT-MNPs) on hen egg-white lysozyme (HEWL) amyloid fibrillization and mature HEWL fibrils. METHODS: Dynamic light scattering (DLS) was used to characterize the physico-chemical properties of studied COAT-MNPs and determine the adsorption potential of their surface towards HEWL. The anti-amyloid properties were studied using thioflavin T (ThT) and tryptophan (Trp) intrinsic fluorescence assays, and atomic force microscopy (AFM). The morphology of amyloid aggregates was analyzed using Gwyddion software. The cytotoxicity of COAT-MNPs was determined utilizing Trypan blue (TB) assay. RESULTS: Agents used for surface modification affect the COAT-MNPs physico-chemical properties and modulate their anti-amyloid potential. The results from ThT and intrinsic fluorescence showed that the inhibitory activities result from the more favorable interactions of COAT-MNPs with early pre-amyloid species, presumably reducing nuclei and oligomers formation necessary for amyloid fibrillization. COAT-MNPs also possess destroying potential, which is presumably caused by the interaction with hydrophobic residues of the fibrils, resulting in the interruption of an interface between ß-sheets stabilizing the amyloid fibrils. CONCLUSION: COAT-MNPs were able to inhibit HEWL fibrillization and destroy mature fibrils with different efficacy depending on their properties, TC-MNPs being the most potent nanoparticles. GENERAL SIGNIFICANCE: The study reports findings regarding the general impact of nanoparticles' surface modifications on the amyloid aggregation of proteins.

Atomic force microscopy as an imaging tool to study the bio/nonbio complexes.

Atomic force microscopy (AFM) besides X-ray crystallography and electron microscopy is one of the most attractive methods to study bio/nonbio complexes. Information on how biomacromolecules interact with nanomaterials under different environmental conditions has important implications for the practice of nanomedicine and concerning the safety of nanomaterials. These complexes cover a broad range both in terms of stability and composition. AFM offers a wealth of structural and functional data about such assemblies. The variety of samples investigated using AFM in biology includes nanometre-sized proteins, lipids, DNA, amyloid fibrils, as well as larger objects such as cells. Herein we choose to review the significance of AFM to study various biological aspects of selected assemblies. We have focused on the exploitation of AFM operating in the air. The presented AFM research offers a unique and often unexpected insight into the structure and function of the bio/nonbio complexes. LAY DESCRIPTION: Atomic force microscopy (AFM) besides X-ray crystallography and electron microscopy is one of the most attractive methods to study bio/nonbio complexes. Information on how biomacromolecules interact with nanomaterials under different environmental conditions has important implications for the practice of nanomedicine and concerning the safety of nanomaterials. These complexes cover a broad range both in terms of stability and composition. AFM offers a wealth of structural and functional data about such assemblies. The variety of samples investigated using AFM in biology includes nanometre-sized proteins, lipids, DNA, amyloid fibrils, as well as larger objects such as cells. Herein we choose to review the significance of AFM to study various biological aspects of selected assemblies. The presented AFM research offers a unique and often unexpected insight into the structure and function of the bio/nonbio complexes. Nature has set us a perfect example of how to elegantly optimise and fine tune different types of processes. The relatively young field of nanotechnology has studied biological processes and exploited their unique strengths as novel materials. The resulting area of bionanotechnology has adopted interaction schemes presented to us by biology, to provide enhanced selectivity, efficiency or versatility of molecular attachment strategies. Two scenarios of this synergistic scheme are: the conjugation of nanostructures as a tool for research in biological science and the conjugation of biological particles as a tool for nanotechnology. The use of nanotechnologies for medical applications raises high expectations regarding diagnosis, drug delivery, gene therapy, and tissue engineering. There is an increasing number of reports using AFM as a nanodiagnostic tool with patient cells. The use of AFM, in combination with more conventional analytical approaches, could inform decisions related to recommendations for treatments. Applying AFM techniques in nanomedicine is becoming well established. Atomic force microscopy (AFM) is one of the most functional and powerful microscopy technology for studying biological and material samples at the nanoscale. It is advantageous because an atomic force microscope can image three-dimensional topography of very small objects. It also provides various types of surface measurements to the needs of scientists and engineers if combined with other electromagnetic waves. It is powerful because an AFM can generate images at atomic resolution with 10-9 m scale resolution height information, with minimum sample preparation. AFM gives details on how biological molecules, such as nucleic acids, proteins, and amyloid aggregates, interact with nanomaterials under different environmental conditions. Here, we have shown several examples of relevant applications of AFM to study structural, functional and mechanical properties useful for the medicine and concerning the safety of nanomaterials.

Inhibition of multidrug resistant Listeria monocytogenes by peptides isolated from combinatorial phage display libraries.

The aim of the study was to isolate and characterize novel antimicrobial peptides from peptide phage library with antimicrobial activity against multidrug resistant Listeria monocytogenes. Combinatorial phage-display library was used to affinity select peptides binding to the cell surface of multidrug resistant L. monocytogenes. After several rounds of affinity selection followed by sequencing, three peptides were revealed as the most promising candidates. Peptide L2 exhibited features common to antimicrobial peptides (AMPs), and was rich in Asp, His and Lys residues. Peptide L3 (NSWIQAPDTKSI), like peptide L2, inhibited bacterial growth in vitro, without any hemolytic or cytotoxic effects on eukaryotic cells. L1 peptide showed no inhibitory effect on Listeria. Structurally, peptides L2 and L3 formed random coils composed of α-helix and ß-sheet units. Peptides L2 and L3 exhibited antimicrobial activity against multidrug resistant isolates of L. monocytogenes with no haemolytic or toxic effects. Both peptides identified in this study have the potential to be beneficial in human and veterinary medicine.