A Comparative Investigation of the Surface Properties of Corn-Starch-Microfibrillated Cellulose Composite Films.

Starch-based materials seem to be an excellent alternative for conventional plastics used in various applications. Microfibralted cellulose can be used to improve the surface properties of starch-based materials. This study aims to analyze the surface properties of starch-microfibrillated cellulose materials. The surface properties of films were evaluated by ATR-FTIR, surface roughness, water wettability, and surface free energy. The surface homogeneity between corn starch and microfibrillated cellulose (MFC) fibers was confirmed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Microscopic analyses of the film surfaces confirm good compatibility of starch and MFC. The addition of MFC increased the surface roughness and polarity of developed starch/MFC materials. The surface roughness parameter has increased from 1.44 ± 0.59 to 2.32 ± 1.13 for pure starch-based materials and starch/MFC material with the highest MFC content. The WCA contact angle has decreased from 70.3 ± 2.4 to 39.1 ± 1.0°, while the surface free energy is 46.2 ± 3.4 to 66.2 ± 1.5 mJ·m-2, respectively. The findings of this study present that surface structure starch/MFC films exhibit homogeneity, which would be helpful in the application of MFC/starch materials for biodegradable packaging purposes.

Surface Modification of Silicone by Dielectric Barrier Discharge Plasma.

The objective of the study was to modify the surface of the silicone rubber, using dielectric barrier discharge (DBD) to improve its hydrophilic properties. The influence of the exposure time, discharge power, and gas composition-in which the dielectric barrier discharge was generated-on the properties of the silicone surface layer were examined. After the modification, the wetting angles of the surface were measured. Then, the value of surface free energy (SFE) and changes in the polar components of the modified silicone over time were determined using the Owens-Wendt method. The surfaces and morphology of the selected samples before and after plasma modification were examined by Fourier-transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR), atomic force microscopy AFM, and X-ray photoelectron spectroscopy (XPS). Based on the research, it can be concluded that the silicone surface can be modified using a dielectric barrier discharge. Surface modification, regardless of the chosen method, is not permanent. The AFM and XPS study show that the structure's ratio of oxygen to carbon increases. However, after less than four weeks, it decreases and reaches the value of the unmodified silicone. It was found that the cause of the changes in the parameters of the modified silicone rubber is the disappearance of oxygen-containing groups on the surface and a decrease in the molar ratio of oxygen to carbon, causing the RMS surface roughness and the roughness factor to return to the initial values.

Anandamide-Modulated Changes in Metabolism, Glycosylation Profile and Migration of Metastatic Melanoma Cells.

An effective therapy for advanced melanoma, a skin cancer with the highest mortality, has not yet been developed. The endocannabinoid system is considered to be an attractive target for cancer treatment. The use of endocannabinoids, such as anandamide (AEA), is considered to be much greater than as a palliative agent. Thus, we checked its influence on various signaling pathways in melanoma cells. Our investigation was performed on four commercial cell lines derived from different progression stages (radial WM35 and vertical WM115 growth phases, lymph node WM266-4 metastasis, solid tumor A375-P metastasis). Cell viability, glucose uptake, quantification of reactive oxygen species production, expression of selected genes encoding glycosyltransferases, quantification of glycoproteins production and changes in the glycosylation profile and migration, as well as in cell elastic properties were analyzed. The cell glycosylation profile was investigated using the biophysical profiling method-the quartz crystal microbalance with dissipation monitoring (QCM-D). Anandamide treatment of only metastatic cells resulted in: an increase in the cell metabolism, a decrease in GFAT-1 and DPM1 expression, followed by a decrease in L1-CAM glycoprotein production, which further influenced the reduction in the cell glycosylation profile and migration. Considering our results, AEA usage is highly recommended in the combined therapy of advanced melanoma.

Novel diagnostic and prognostic factors for the advanced melanoma based on the glycosylation-related changes studied by biophysical profiling methods.

Melanoma is a life-threatening disease due to the early onset of metastasis and frequent resistance to the applied treatment. For now, no single histological, immunohistochemical or serological biomarker was able to provide a precise predictive value for the aggressive behavior in melanoma patients. Thus, the search for quantifying methods allowing a simultaneous diagnosis and prognosis of melanoma patients is highly desirable. By investigating specific molecular interactions with some biosensor-based techniques, one can determine novel prognostic factors for this tumor. In our previous study, we have shown the possibility of a qualitative in vitro distinguishing the commercially available melanoma cells at different progression stages based on the measurements of the lectin Concanavalin A interacting with surface glycans present on cells. Here, we present the results of the quantitative diagnostic and prognostic study of both commercial and patient-derived melanoma cells based on the evaluation of two novel factors: lectin affinity and glycan viscoelastic index obtained from the quartz crystal microbalance with dissipation monitoring (QCM-D) measurements. Two approaches to the QCM-D measurements were applied, the first uses the ability of melanoma cells to grow as a monolayer of cells on the sensor (cell-based sensors), and the second shortens the time of the analysis (suspension cell based-sensors). The results were confirmed by the complementary label-free (atomic force microscopy, AFM; and surface plasmon resonance, SPR) and labeling (lectin-ELISA; and microscale thermophoresis, MST) techniques. This new approach provides additional quantitative diagnosis and a personalized prognosis which can be done simultaneously to the traditional histopathological analysis.

The Multifaceted Roles of Mast Cells in Immune Homeostasis, Infections and Cancers.

Mast cells (MCs) play important roles in normal immune responses and pathological states. The location of MCs on the boundaries between tissues and the external environment, including gut mucosal surfaces, lungs, skin, and around blood vessels, suggests a multitude of immunological functions. Thus, MCs are pivotal for host defense against different antigens, including allergens and microbial pathogens. MCs can produce and respond to physiological mediators and chemokines to modulate inflammation. As long-lived, tissue-resident cells, MCs indeed mediate acute inflammatory responses such as those evident in allergic reactions. Furthermore, MCs participate in innate and adaptive immune responses to bacteria, viruses, fungi, and parasites. The control of MC activation or stabilization is a powerful tool in regulating tissue homeostasis and pathogen clearance. Moreover, MCs contribute to maintaining the homeostatic equilibrium between host and resident microbiota, and they engage in crosstalk between the resident and recruited hematopoietic cells. In this review, we provide a comprehensive overview of the functions of MCs in health and disease. Further, we discuss how mouse models of MC deficiency have become useful tools for establishing MCs as a potential cellular target for treating inflammatory disorders.

Studying Viscoelastic Changes of Skin Cells Using QCM-D Measurements.

The viscoelastic properties of cells are responsible for the adhesion process to different surfaces and for cell motility. Therefore, it is very important to develop specific, label-free biosensors with the use of whole cells to study the effect of various factors on the survival and properties of selected type of normal and pathological cells. The quartz crystal microbalance with dissipation energy monitoring (QCM-D) is a technique which enables to track these changes in cells during real-time experiments. One of the applied procedures of the evaluation of the cells' viscoelastic changes is based on the investigations of interactions between specific, different glycans, present on the surface of the primary tumor and its metastases with specific lectins. Two procedures have been developed to detect the differences in the cellular glycosylation profile using cell-based sensors (adherent cells cultured on sensors) and suspension cell-based sensors (adherent cells mechanically detached and inserted into the QCM-D chamber with a sensor). Furthermore, in this work some cell-based sensor regeneration protocols have been described and a lectin-ELISA assay with a fluorescently labeled lectin, thus enabling a qualitative and quantitative tracking of each step of the lectin-glycan binding and unbinding process performed on whole cells.

A Novel and Effective Method for Human Primary Skin Melanocytes and Metastatic Melanoma Cell Isolation.

The development of an effective method of melanocyte isolation and culture is necessary for basic and clinical studies concerning skin diseases, including skin pigmentation disorders and melanoma. In this paper, we describe a novel, non-enzymatic and effective method of skin melanocyte and metastatic melanoma cell isolation and culture (along with the spontaneous spheroid creation) from skin or lymph node explants. The method is based on the selective harvesting of melanocytes and melanoma cells emigrating from the cultured explants. Thereby, isolated cells retain their natural phenotypical features, such as expression of tyrosinase and Melan-A as well as melanin production and are not contaminated by keratinocytes and fibroblasts. Such melanocyte and melanoma cell cultures may be very useful for medical and cosmetology studies, including studies of antitumor therapies.

Biophysical characterization of melanoma cell phenotype markers during metastatic progression.

Melanoma is the most fatal form of skin cancer, with increasing prevalence worldwide. The most common melanoma genetic driver is mutation of the proto-oncogene serine/threonine kinase BRAF; thus, the inhibition of its MAP kinase pathway by specific inhibitors is a commonly applied therapy. However, many patients are resistant, or develop resistance to this type of monotherapy, and therefore combined therapies which target other signaling pathways through various molecular mechanisms are required. A possible strategy may involve targeting cellular energy metabolism, which has been recognized as crucial for cancer development and progression and which connects through glycolysis to cell surface glycan biosynthetic pathways. Protein glycosylation is a hallmark of more than 50% of the human proteome and it has been recognized that altered glycosylation occurs during the metastatic progression of melanoma cells which, in turn facilitates their migration. This review provides a description of recent advances in the search for factors able to remodel cell metabolism between glycolysis and oxidative phosphorylation, and of changes in specific markers and in the biophysical properties of cells during melanoma development from a nevus to metastasis. This development is accompanied by changes in the expression of surface glycans, with corresponding changes in ligand-receptor affinity, giving rise to structural features and viscoelastic parameters particularly well suited to study by label-free biophysical methods.

Tracking of Glycans Structure and Metallomics Profiles in BRAF Mutated Melanoma Cells Treated with Vemurafenib.

Nearly half of patients with advanced and metastatic melanomas harbor a BRAF mutation. Vemurafenib (VEM), a BRAF inhibitor, is used to treat such patients, however, responses to VEM are very short-lived due to intrinsic, adaptive and/or acquired resistance. In this context, we present the action of the B-Raf serine-threonine protein kinase inhibitor (vemurafenib) on the glycans structure and metallomics profiles in melanoma cells without (MeWo) and with (G-361) BRAF mutations. The studies were performed using α1-acid glycoprotein (AGP), a well-known acute-phase protein, and concanavalin A (Con A), which served as the model receptor. The detection of changes in the structure of glycans can be successfully carried out based on the frequency shifts and the charge transfer resistance after interaction of AGP with Con A in different VEM treatments using QCM-D and EIS measurements. These changes were also proved based on the cell ultrastructure examined by TEM and SEM. The LA-ICP-MS studies provided details on the metallomics profile in melanoma cells treated with and without VEM. The studies evidence that vemurafenib modifies the glycans structures and metallomics profile in melanoma cells harboring BRAF mutation that can be further implied in the resistance phenomenon. Therefore, our data opens a new avenue for further studies in the short-term addressing novel targets that hopefully can be used to improve the therapeutic regiment in advanced melanoma patients. The innovating potential of this study is fully credible and has a real impact on the global patient society suffering from advanced and metastatic melanomas.

Sulfone derivatives enter the cytoplasm of Candida albicans sessile cells.

Since our study showed that sulfone derivatives' action mode creates a lesser risk of inducing widespread resistance among Candida spp., we continued verifying sulfones' antifungal activity using the following newly synthesized derivatives: bromodichloromethy-4-hydrazinyl-3-nitrophenyl sulfone (S1), difluoroiodomethyl-4-hydrazinyl-3-nitrophenyl sulfone (S2), and chlorodifluoromethyl-4-hydrazinyl-3-nitrophenyl sulfone (S3). As the mechanism by which sulfones gain access to the cytoplasm has not been elucidated yet, in order to track S1-3, we coupled their hydrazine group with BODIPY (final S1-3 BODIPY-labelled were named SB1-3). This approach allowed us to follow the vital internalization and endocytic routing of SB1-3, while BODIPY interacts primarily with fungal surfaces, thus confirming that S1-3 and their counterparts SB1-2 behaved as non-typical agents by damaging the cell membrane and wall after being endocytosed (SB1-3 fluorescence visible inside the unlysed sessile cells). Thus greatly decreasing the likelihood of the appearance of strains resistance. Core sulfones S1-3 are a promising alternative not only to treat planktonic C. albicans but also biofilm-embedded cells. In the flow cytometric analysis, the planktonic cell surface was digested by S1-3, which made the externalized PS accessible to AnnexinV binding and PI input (accidental cell death ACD). The occurrence of ACD as well as apoptosis (crescent-shaped nuclei) and anoikis of sessile cells (regulated cell death by 100%-reduction in attachment to epithelium) was assessed through monitoring the AO/PI/HO342 markers. CLSM revealed the invasion of S1-3 and SB1-3 in C. albicans without inducing cell lysis. This was a novel approach in which QCM-D was used for real-time in situ detection of viscoelastic changes in the C. albicans biofilm, and its interaction with S1 as a representative of the sulfones tested. S1 (not toxic in vivo) is a potent fungicidal agent against C. albicans and could be administered to treat invasive candidiasis as a monotherapy or in combination with antifungal agents of reference to treat C. albicans infections.

Amphiphilic Polymethyloxazoline-Polyethyleneimine Copolymers: Interaction with Lipid Bilayer and Antibacterial Properties.

Polycations, mimicking activity of antibacterial peptides, belong to an important class of molecules investigated as a support or as an alternative to antibiotics. In this work, studies of modified linear amphiphilic statistical polymethyloxazoline (PMOX) and polyethyleneimine copolymers (PMOX_PEI) series are presented. Variation of PEI content in the structure results in controllable changes of polymeric aggregates zeta potential. The structure with the highest positive charge shows the best antimicrobial activity, well visible in tests against model Gram-positive and Gram-negative bacteria, fungi, and mycobacterium strains. The polymer toxicity is evaluated with MTT and hemolysis assay as a reference. Quartz crystal microbalance (QCM-D) is used to investigate interaction between polycations and a model lipid membrane. Polymer activity correlates well with molecular structure, showing that amphiphilic component is altering polymer behavior in contact with the lipid bilayer.

The Effect of Anti-aging Peptides on Mechanical and Biological Properties of HaCaT Keratinocytes.

Atomic force microscopy (AFM) and fluorescence microscopy was applied to determine the influence of the anti-aging peptides on the morphology and the mechanical properties of keratinocytes. Immortalized human keratinocytes (HaCaT) were treated with two anti-aging bioactive peptides: Acetyl Tetrapeptide-2 and Acetyl Hexapeptide-50 (Lipotec). The AFM measurement of the keratinocyte stiffness were carried after 48 h exposure at an indentation depth of 200 nm. AFM analysis showed increase of the cell stiffness for cells treated with Acetyl Tetrapeptide-2 (P1) in concentration range. Acetyl Hexapeptide-50 (P2) at concentration of 0.05 µg/ml also increased the stiffness of HaCaT cells but at higher concentrations 0.5 and 5 µg/ml cell stiffness was lower as compared to untreated control. Fluorescence microscopy revealed remodeling of actin filaments dependent on the concentration of P2 peptide. The mechanical response of HaCaT cells treated with P2 peptide corresponds to change of transcription level of ACTN1 and SOD2 which activity was expected to be modulated by P2 treatment.

The effect of polymeric membrane surface on HaCaT cell properties.

The control of the surface properties is an important issue for applicability of polymer membranes interacting with cells. In this work, the influence of surface roughness and stiffness of two polymer membranes on viability and mechanical properties of keratinocytes was studied. Terpolimer polyglicolide, polycaprolactone and polylactide, (PGA-PCL-PLA) and copolymer polycaprolactone, polyglicolide (PGA-PCL) substrates were used for membranes fabrication. Surface modification - the hydrolysis of the obtained membranes was carried out. The analysis of membranes' surface properties revealed that RMS surface roughness and roughness factor of PGA-PCL-PLA membrane decreased after hydrolysis while its stiffness increased. In contrast, the PGA-PCL membrane stiffness was only slightly affected by NaOH treatment. Immortalized human keratinocytes (HaCaT) were grown under standard conditions on the surface of the studied membranes and characterized by means of atomic force microscopy and fluorescence microcopy. The results showed the substrate-dependent effect on cells' properties.

AFM and QCM-D as tools for the distinction of melanoma cells with a different metastatic potential.

Malignant melanoma is one of the most dangerous skin cancer originating from melanocytes. Thus, an early and proper melanoma diagnosis influences significantly the therapy efficiency. The melanoma recognition is still difficult, and generally, relies on subjective assessments. In particular, there is a lack of quantitative methods used in melanoma diagnosis and in the monitoring of tumour progression. One such method can be the atomic force microscopy (AFM) working in the force spectroscopy mode combined with quartz crystal microbalance (QCM), both applied to quantify the molecular interactions. In our study we have compared the recognition of mannose type glycans in melanocytes (HEMa-LP) and melanoma cells originating from the radial growth phase (WM35) and from lung metastasis (A375-P). The glycosylation level on their surfaces was probed using lectin concanavalin A (Con A) from Canavalia ensiformis. The interactions of Con A with surface glycans were quantified with both AFM and QCM techniques that revealed the presence of various glycan structural groups in a cell-dependent manner. The Con A - mannose (or glucose) type glycans present on WM35 cell surface are rather short and less ramified while in A375-P cells, Con A binds to long, branched mannose and glucose types of oligosaccharides.

The effect of delphinidin on the mechanical properties of keratinocytes exposed to UVB radiation.

The usage of active compounds of dietary phytochemicals in prevention of UV-induced skin diseases is increasingly gaining attention in the development of skin care products. The purpose of this study was to measure the influence of delphinidin (as a botanical agent) on the cell mechanical properties evaluated by the atomic force microscopy (AFM) technique in the immortalized human keratinocyte cell line (HaCaT) exposed to UVB radiation. The cells were treated with various doses of UVB radiation with and without pre and post-treatment with selected concentrations of delphinidin. The measurements of the elastic properties revealed that the exposure of HaCaT cells to high dose of the UVB radiation (100mJ/cm2) caused a decrease in the cell elastic modulus. It was accompanied by the decrease of metabolic activity, rearrangement of actin cytoskeleton and disappearance of the cell repair marker 53BP1. Both pre-treatment and post-treatment with delphinidin at non-cytotoxic concentrations (5 or 10µM), restored the elastic modulus of irradiated keratinocytes. A direct AFM analysis showed that the UVB-mediated decrease of the cell stiffness was restored more effectively when cells were treated with delphinidin after the UVB irradiation. The results demonstrate the regenerative effect of delphinidin on the mechanical properties of cells exposed to UVB radiation (100mJ/cm2), which may be due to antioxidant and inhibitory effect on matrix metalloproteinases activation.

Unusual penetration of phospholipid mono- and bilayers by Quillaja bark saponin biosurfactant.

The interactions between a model phospholipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and a biosurfactant Quillaja Bark Saponin (QBS) obtained from the bark of Quillaja saponaria Molina were studied using simple models of biological membranes. QBS is known to interact strongly with the latter, exerting a number of haemolytic, cytotoxic and anti-microbial actions. The interaction of QBS dissolved in the subphase with DPPC monolayers and silicon-supported bilayers was studied above the cmc (10(-3)M). Surface pressure relaxation and surface dilatational rheology combined with quartz crystal microbalance (QCM) and neutron reflectivity (NR) were employed for this purpose. The DPPC-penetrating abilities of QBS are compared with those of typical synthetic surfactants (SDS, CTAB and Triton X-100). We show that the penetration studies using high surface activity (bio)surfactants should be performed by a subphase exchange, not by spreading onto the surfactant solution. In contrast to the synthetic surfactants of similar surface activity, QBS does not collapse DPPC mono- and bilayers, but penetrates them, improving their surface dilatational elastic properties even in the highly compressed solid state. The dilatational viscoelasticity modulus increases from 204 mN/m for pure DPPC up to 310 mN/m for the QBS-penetrated layers, while it drops to near zero values in the case of the synthetic surfactants. The estimated maximum insertion pressure of QBS into DPPC monolayers exceeds the maximum surface pressure achievable in our setup, in agreement with the surface rheological response of the penetrated layers.

Effect of hydration of sugar groups on adsorption of Quillaja bark saponin at air/water and Si/water interfaces.

Adsorption of a natural glycoside surfactant Quillaja bark saponin ("QBS", Sigma Aldrich 84510) was studied at the air/water and Si/water interfaces using a combination of surface pressure (SP), surface dilatational rheology, neutron reflectivity (NR), Infra-Red Attenuated Total Reflection Spectroscopy (IR ATR) and Quartz Crystal Microbalance (QCM). The adsorbed layers formed at the air/water interface are predominantly elastic, with the dilatational surface storage modulus reaching the maximum value of E'=184 mN/m. The NR results point to a strong hydration of the adsorbed layers (about 65% hydration, corresponding to about 60 molecules of water per one QBS molecule), most likely related to the presence of multiple sugar groups constituting the glycone part of the QBS molecules. With a layer thickness of 19 Å, the adsorbed amount obtained from NR seems largely underestimated in comparison to the value obtained from the surface tension isotherm. While this high extent of hydration does not prevent formation of dense and highly elastic layers at the air-water surface, QBS adsorption at the Si/water interface is much weaker. The adsorption isotherm of QBS on Si obtained from the QCM study reflects much lower affinity of highly hydrated and negatively charged saponin molecules to the Si/water interface. We postulate that at the air/water interface, QBS adsorbs through the triterpene aglycone moiety. In contrast, weak hydrogen bonding between the glycone part and the surface silanol groups of Si is responsible for QBS adsorption on more polar Si/water interface.

The influence of surfactants and hydrolyzed proteins on keratinocytes viability and elasticity.

BACKGROUND/PURPOSE: The knowledge how surfactants and hydrolyzed proteins influence the elastic properties of living epidermal keratinocytes is sparse. We demonstrate that the stiffness of cells measured by atomic force microscope (AFM) can be correlated with viability test. METHODS AND MATERIALS: The effects of sodium lauryl sulphate (SLS) and hydrolyzed collagen (HK) of molecular weight 9 kDa were examined with respect to human keratinocytes viability and elasticity. MTT assay was applied to determine the survival fraction of keratinocytes treated with SLS and HK solutions of various molar ratios. The AFM measurements of the keratinocytes stiffness were carried out immediately after the exposure of cells to the SLS and HK, respectively. RESULTS: The increase of the SLS concentration resulted in the decrease of cells proliferation and this effect was inhibited by addition of HK. The strongest inhibition was observed for the SLS:HK molar ratio equals to 2:1. AFM study shows decrease in the cell stiffness for cells treated with SLS. Fluorescence microscopy reveals remodeling of actin filaments of SLS-treated cells. SLS:HK mixture treatment results in mechanical stiffness close to untreated cells. CONCLUSION: These results provide possible correlations between mechanical properties and viability of keratinocytes when the chemical stress occurs.

Reaction pathway and free energy profile determined for specific recognition of oligosaccharide moiety of carboxypeptidase Y.

The interaction of mannose specific lectin (from Lens culinaris, LcL) with the carbohydrate moiety of carboxypeptidase Y (CaY) was studied using both atomic force microscope (AFM) and quartz crystal microbalance with dissipation monitoring (QCM-D). The AFM enables to determine the positions of energy barriers present in the energy landscape of the single complex undergoing dissociation. The QCM-D measurements allow the estimation of the quantitative parameters characterizing the kinetics of the studied molecular interaction (namely the association and dissociation rate constants and the association constant). The use of both methods not only delivers the complementary characterization of kinetic and thermodynamic parameters but also permits to investigate the mechanism of the binding and unbinding of the molecules. The results for LcL were compared with those obtained for concanavalin A i.e. lectin, which interacts with the carbohydrate moiety on a similar way.