Morphological Dynamics of Leukemia Cells on TiO2 Nanoparticle Coatings Studied by AFM

Coatings of modified TiO2 nanoparticles (TiO2-m) have been shown to effectively and selectively trap non-adherent cancer cells, with an enormous potential for applications in photodynamic therapy (PDT). Leukemia cells have a remarkable affinity for TiO2-m coatings, adhering to the surface by membrane structures and exhibiting morphologic characteristics of amoeboid locomotion. However, the details of the cell–substrate interaction induced by the TiO2-m coating remain elusive. With the aim to obtain a better understanding of this phenomenon, leukemia cell adhesion to such coatings was characterized by atomic force microscopy (AFM) for short contact times up to 60 min. The cell and membrane morphological parameters mean cell height, contact area, cell volume, and membrane roughness were determined at different contact times. These results reveal cell expansion and contraction phases occurring during the initial stage of adhesion. Subsequently, the leukemic cells reach what appears to be a new resting state, characterized by pinning of the cell membrane by TiO2-m nanoparticle aggregates protruding from the coating surface.

Morphometric and Nanomechanical Features of Platelets from Women with Early Pregnancy Loss Provide New Evidence of the Impact of Inherited Thrombophilia

Pregnancy is associated with hypercoagulation states and increased thrombotic risk, especially in women with thrombophilia. We combine atomic force microscopy (AFM) and flow cytometry to examine the morphology and nanomechanics of platelets derived from women with early pregnancy loss (EPL) and control pregnant (CP) and non-pregnant (CNP) women. Both control groups exhibit similar morphometric parameters (height and surface roughness) and membrane stiffness of platelets. EPL patients’ platelets, on the other hand, are more activated than the control groups, with prominent cytoskeletal rearrangement. In particular, reduced membrane roughness (22.9 ± 6 nm vs. 39.1 ± 8 nm) (p < 0.05) and height (692 ± 128 nm vs. 1090 ± 131 nm) (p < 0.05), strong alteration in the membrane Young modulus, increased production of platelets’ microparticles, and higher expression of procoagulant surface markers, as well as increased occurrence of thrombophilia (FVL, FII20210A, PLA1/A2, MTHFR C677T or 4G/5G PAI-1) polymorphisms were found. We suggest that the carriage of thrombophilic mutations triggers structural and nanomechanical abnormalities in platelets, resulting in their increased activation. The activation state of platelets can be well characterized by AFM, and the morphometric and nanomechanical characteristics might serve as a new criterion for evaluation of the cause of miscarriage and offer the prospect of an innovative approach serving for diagnostic purposes.

Relationships among Permeability, Membrane Roughness, and Eukaryote Inhabitation during Submerged Gravity-Driven Membrane (GDM) Filtration

Gravity-driven membrane (GDM) filtration is one of the promising technologies for decentralized water treatment systems due to its low cost, simple operation, and convenient maintenance. The objective of this study was to evaluate the permeability of submerged GDM filtration with three different membranes, i.e., polyethersulfone and polyvinylidene difluoride ultrafiltration (PES-UF and PVDF-UF) and polytetrafluoroethylene microfiltration membrane (PTFE-MF). The GDM system was operated using lake water for about one year. The determined average permeability values were high for PVDF-UF (192.9 L/m2/h/bar (LMH/bar)) and PTFE-MF (80.6 LMH/bar) and relatively lower for PES-UF (46.1 LMH/bar). The observed higher permeability for PVDF-UF and PTFE-MF was thought to be related to the rougher surface of these two membranes compared to PES-UF. The fouling layers of PVDF-UF and PTFE-MF were characterized by high biomass and the presence of a number of nematodes, while PES-UF showed a thin fouling layer with no nematode. The relatively high and fluctuated permeability of PVDF-UF and PTFE-MF could thus be attributed to the high biological activity of nematodes making the fouling layer more loose and porous. This was supported by a good linear relationship among the permeability, biomass concentration, and the number of nematodes in the fouling layers. These results provide important insights into membrane selection as a critical factor affecting the flux performance of the GDM filtration system for a decentralized drinking water supply.

A STUDY OF THE ULTRASTRUCTURE OF THE SURFACE OF THE TRANSPLANTABLE LINE VERO CELLS INFECTED WITH THE RABIES VIRUS (RABV, LISSAVIRUS, RHABDOVIRIDAE)

Characteristics of the effect of attenuated rabies virus strain «Moscow 3253» on morphological parameters of transplantable line Vero cells were studied by atomic force microscopy (AFM). Methods based on phase contrast microscopy and immunofluorescence were used to confirm the specificity of interaction and to identify the infectious activity of the rabies virus. Images of intact Vero cells and Vero cells infected with rabies virus were obtained at different periods of cultivation. The character of changes in the cell dimensions (length, width, height) and the cell membrane roughness depending on the rabies virus cultivation time was determined. During the observation period both increases and decreases in the size of the cells were recorded. The size of the infected cells exceeded that of the intact. An increase in the membrane roughness in cells exposed to rabies occurred during the entire period of observation, since the first hours of the interaction of the virus with the cell, while the intact Vero cells exhibited only minor changes in the membrane surface roughness, which were not dependent on the age of the culture. The dependence of the increase in the cell membrane roughness on the infecting dose of the rabies virus was determined. The obtained results open up the prospect of developing a methodological approach to the quantitative in vitro evaluation of the rabies virus using AFM. Changes in the cell membrane roughness appear to be the most indicative parameter for such evaluation.

Bioactive Hybrid Composite Membrane with Enhanced Antimicrobial Properties for Biomedical Applications

<p class="p1"> </p><p class="p2"><span class="s1"> </span><em>Azadirachta indica </em>extract has been explored as an antibiotic in hygienic chitosan matrix system to enhance antimicrobial and medicinal property in a cost effective manner. The hygienic composite system has been successfully fabricated via solvent casting. The antibacterial activities of the hybrid system were examined by agar diffusion method against gram positive <em>S.aureus </em>and gram negative <em>K. pneumoniae. </em>From conventional antibacterial test for 24 h, the system exhibited an excellent antimicrobial activity against both bacterial strains in ranges of 1.2 cm - 1.5 cm for <em>S. aureus </em>and 1.8 cm <em>- </em>2.3 cm for <em>K. pneumoniae </em>Fourier transform infrared spectroscopy revealed successfully embedded A. indica on the chitosan substrate via weak electrostatic interaction, resulting in the easy release of the additive. Moreover, atomic force microscopy showed a membrane roughness of 0.084 nm which confirms the uniform distribution of the additive throughout the membrane. These hybrid membranes have potential applications in skin tissue engineering, wound healing and as coatings for implantable scaffold material.</p>