scholarly journals ToF-SIMS and AFM Characterization of Brown Cosmetic Contact Lenses: From Structural Analysis to the Identification of Pigments

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Seon Hee Kim ◽  
Jihye Lee ◽  
Yun Jung Jang ◽  
Kang-Bong Lee ◽  
Yeonhee Lee
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Contact Lenses ◽  
Analytical Techniques ◽  
Pigment Layer ◽  
Force Microscopy ◽  
Soft Contact Lenses ◽  
Atomic Force ◽  
Tof Sims ◽  
The Cross ◽  
Specific Fragment

Over the years, soft contact lenses for vision correction and cosmetic and therapeutic purposes have been greatly improved. For cosmetic contact lenses, the pigments need to be nontoxic, and the position of the pigment layer is particularly important because of the risks posed by pigment elution and the roughness of the lens surface. In this paper, we characterized the properties of brown cosmetic contact lenses made by three different manufacturers using surface analytical techniques. The surface topographies of the noncolored and colored parts were obtained by atomic force microscopy (AFM), and the position and composition of the pigment layer were determined by analyzing the cross section of the contact lenses using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). The influence of pigment location on surface roughness was also examined. In addition, to find the method of the evaluation for the risk of surface elution of the pigments in the colored parts, the mass spectra and ion images of the surfaces were obtained by time-of-flight secondary ion mass spectrometry (ToF-SIMS) with a new sample preparation. From the ToF-SIMS spectra, we observed specific fragment ions of the poly(hydroxyethyl methacrylate) (PHEMA) polymer and found differences in the composition of the pigment layer depending on the manufacturers. The cross-sectioned image and 3D chemical characterizations of metallic and specific ions in the brown cosmetic contact lenses clearly indicated the spatial distribution and location of the pigment layer that can be used for the evaluation of pigment elution.

Microscopic observation of unworn siloxane-hydrogel soft contact lenses by atomic force microscopy

2006 ◽  
Vol 76B (2) ◽  
pp. 412-418 ◽  
Author(s):  
José M. González-Méijome ◽  
Antonio López-Alemany ◽  
José B. Almeida ◽  
Manuel A. Parafita ◽  
Miguel F. Refojo
Keyword(s):  
Atomic Force Microscopy ◽  
Microscopic Observation ◽  
Contact Lenses ◽  
Soft Contact ◽  
Force Microscopy ◽  
Soft Contact Lenses ◽  
Atomic Force

Cleanability of Soiled Stainless Steel as Studied by Atomic Force Microscopy and Time of Flight Secondary Ion Mass Spectrometry

2001 ◽  
Vol 64 (1) ◽  
pp. 87-93 ◽  
Author(s):  
R. D. BOYD ◽  
D. COLE ◽  
D. ROWE ◽  
J. VERRAN ◽  
A. J. PAUL ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Atomic Force Microscopy ◽  
Stainless Steel ◽  
Surface Defects ◽  
Secondary Ion Mass Spectrometry ◽  
Time Of Flight ◽  
Analytical Techniques ◽  
Force Microscopy ◽  
Atomic Force ◽  
Secondary Ion

The hygienic status of food contact surfaces can deteriorate with wear. Effective cleaning regimes must remove any adsorbed organic material as well as microorganisms. Previous work has determined the extent of surface wear occurring on a stainless steel surface within the food industry, and we have reproduced representative samples in vitro. Two surface analytical techniques, atomic force microscopy and time of flight secondary ion mass spectrometry were combined with fluorescence microscopy to give detailed analysis of stainless steel surfaces fouled with starch and milk powder, then cleaned with water either by a spray or brushing method. It was found that the surface cleanability is affected by the cleaning regime and the surface roughness, not only the average vertical roughness but also by the shape of the surface defects, with sharp scratches more difficult to clean than wider surface defects. Spray cleaning with distilled water was found to be a selective method by preferentially removing proteinaceous material more easily than fatty acid ester material. The analytical techniques employed provided information on selective cleanability and surface topography at a hitherto unexplored level, and the information gained may be of value in the design and investigation of novel cleaning regimes and hygienic surfaces.

scholarly journals New drug delivery system in ophthalmology: results studying the surface structure of soft contact lenses from various polymer

2021 ◽  
Vol 40 ◽  
pp. 03002
Author(s):  
Elena Zhilyakova ◽  
Denis Naplekov ◽  
Anastasia Malyutina ◽  
Alexander Bondarev ◽  
Oleg Novikov
Keyword(s):  
Surface Structure ◽  
Large Scale ◽  
Contact Lenses ◽  
Absorption Capacity ◽  
Soft Contact ◽  
Force Microscopy ◽  
Soft Contact Lenses ◽  
Atomic Force ◽  
Medicinal Substances ◽  
Pore Properties

The development of an ophthalmic therapeutic system includes research on the spatial structure of soft contact lens polymers and the study of the processes of saturation and release of medicinal substances from them. This allows you to determine the methods of saturation of contact lenses with medicinal agents and will open up new opportunities in the treatment of ophthalmological diseases. The purpose of this preliminary fragment of large-scale research was to study the surface structure of soft contact lenses made of various polymers. The following polymers were used in the work: Nelfilcon A, Hilafilcon B, Nezofilcon A, Etafilcon A, Lotrafilcon B. The following pharmaceutical substances were used: Brimonidine Tartrate, Betaxolol Hydrochloride, Pyridoxine Hydrochloride. The surface structure of soft contact lenses was studied using atomic force microscopy. Each material under study has a different surface character, which together with the differences in pore properties determines its individuality. Based on this, it should be assumed that the surface of soft contact lenses affects the possibility of their potential use as a means of delivering drug agent molecules to the eye tissues. In all cases of soft contact saturation, the highest absorption capacity was demonstrated by Hilafilcon B and Etafilcon A with a similar surface.

scholarly journals Extracellular Vesicles Analysis in the COVID-19 Era: Insights on Serum Inactivation Protocols towards Downstream Isolation and Analysis

Cells ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 544
Author(s):  
Roberto Frigerio ◽  
Angelo Musicò ◽  
Marco Brucale ◽  
Andrea Ridolfi ◽  
Silvia Galbiati ◽  
...  
Keyword(s):  
Extracellular Vesicles ◽  
Analytical Techniques ◽  
Heat Inactivation ◽  
Force Microscopy ◽  
Atomic Force ◽  
Droplet Pcr ◽  
Detergent Treatment ◽  
Routine Procedures ◽  
The Impact ◽  
Mirna Content

Since the outbreak of the COVID-19 crisis, the handling of biological samples from confirmed or suspected SARS-CoV-2-positive individuals demanded the use of inactivation protocols to ensure laboratory operators’ safety. While not standardized, these practices can be roughly divided into two categories, namely heat inactivation and solvent-detergent treatments. These routine procedures should also apply to samples intended for Extracellular Vesicles (EVs) analysis. Assessing the impact of virus-inactivating pre-treatments is therefore of pivotal importance, given the well-known variability introduced by different pre-analytical steps on downstream EVs isolation and analysis. Arguably, shared guidelines on inactivation protocols tailored to best address EVs-specific requirements will be needed among the analytical community, yet deep investigations in this direction have not yet been reported. We here provide insights into SARS-CoV-2 inactivation practices to be adopted prior to serum EVs analysis by comparing solvent/detergent treatment vs. heat inactivation. Our analysis entails the evaluation of EVs recovery and purity along with biochemical, biophysical and biomolecular profiling by means of a set of complementary analytical techniques: Nanoparticle Tracking Analysis, Western Blotting, Atomic Force Microscopy, miRNA content (digital droplet PCR) and tetraspanin assessment by microarrays. Our data suggest an increase in ultracentrifugation (UC) recovery following heat treatment; however, it is accompanied by a marked enrichment in EVs-associated contaminants. On the other hand, solvent/detergent treatment is promising for small EVs (<150 nm range), yet a depletion of larger vesicular entities was detected. This work represents a first step towards the identification of optimal serum inactivation protocols targeted to EVs analysis.

scholarly journals High resolution nanoscale chemical analysis of bitumen surface microstructures

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ayse N. Koyun ◽  
Julia Zakel ◽  
Sven Kayser ◽  
Hartmut Stadler ◽  
Frank N. Keutsch ◽  
...  
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Force Microscopy ◽  
Photo Oxidation ◽  
Atomic Force ◽  
Para Phase ◽  
Key Sites ◽  
Respective Surface ◽  
Surface Domains ◽  
Surface Microstructures ◽  
First Time

AbstractSurface microstructures of bitumen are key sites in atmospheric photo-oxidation leading to changes in the mechanical properties and finally resulting in cracking and rutting of the material. Investigations at the nanoscale remain challenging. Conventional combination of optical microscopy and spectroscopy cannot resolve the submicrostructures due to the Abbe restriction. For the first time, we report here respective surface domains, namely catana, peri and para phases, correlated to distinct molecules using combinations of atomic force microscopy with infrared spectroscopy and with correlative time of flight—secondary ion mass spectrometry. Chemical heterogeneities on the surface lead to selective oxidation due to their varying susceptibility to photo-oxidation. It was found, that highly oxidized compounds, are preferentially situated in the para phase, which are mainly asphaltenes, emphasising their high oxidizability. This is an impressive example how chemical visualization allows elucidation of the submicrostructures and explains their response to reactive oxygen species from the atmosphere.

scholarly journals ToF-SIMS Investigations of Tip-Surface Chemical Interactions in Atomic Force Microscopy on a Combined AFM/ToF-SIMS Platform

2017 ◽  
Vol 23 (S1) ◽  
pp. 2082-2083
Author(s):  
Chance C. Brown ◽  
Anton V. Ievlev ◽  
Petro Maksymovych ◽  
Sergei V. Kalinin ◽  
Olga S. Ovchinnikova
Keyword(s):  
Atomic Force Microscopy ◽  
Surface Chemical ◽  
Chemical Interactions ◽  
Force Microscopy ◽  
Atomic Force ◽  
Tof Sims

SFM and TOF-SIMS Study of Novel Self-Organization phenomena in mixed LB monolayers

2002 ◽  
Vol 738 ◽  
Author(s):  
B. Pignataro ◽  
L. Sardone ◽  
A. Licciardello ◽  
G. Marletta
Keyword(s):  
Secondary Ion Mass Spectrometry ◽  
Scanning Force Microscopy ◽  
Lateral Force ◽  
Self Organization ◽  
High Mass ◽  
Molar Ratio ◽  
Force Microscopy ◽  
Tof Sims ◽  
Wide Range ◽  
Scanning Force

ABSTRACTMixed monolayers of dimyristoylphosphatidylcholine (DMPC) and quercetin palmitate (QP) in a molar ratio of 25/75 have been transferred on mica and oxygen plasma cleaned silicon by the Langmuir-Blodgett (LB) technique at different subphase temperatures. Scanning Force Microscopy (SFM) in height, phase and lateral force modes has been employed to investigate the structural and mechanical features at nanoscopic level of these samples. Although the two molecules show a wide range of miscibility at 37 °C, they give rise to phase separation at 10 °C. This last system provides a new example of nanometric scale self-organization. In particular spiral shaped domains rising from the wrapping-up of nanoscopic fiber-like structures have been observed. The high resolution achieved by the use of the dynamic scanning force microscopy operating in the net attractive regime allow to visualize characteristic nanoscopic rupture points along the supramolecular fibers. High mass resolution Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) spectra showed DMPC- as well as QP-related peaks. The ToF-SIMS spectra from the nanostructured samples (10 °C) have been compared with those from the homogeneous ones (37 °C). The phase separated samples provides interesting secondary ions that highlight the QP supramolecular condensation within the fiber-like structures.

scholarly journals Synthesis of Metarhizium anisopliae–Chitosan Nanoparticles and Their Pathogenicity against Plutella xylostella (Linnaeus)

2021 ◽  
Vol 10 (1) ◽  
pp. 1
Author(s):  
Jianhui Wu ◽  
Cailian Du ◽  
Jieming Zhang ◽  
Bo Yang ◽  
Andrew G. S. Cuthbertson ◽  
...  
Keyword(s):  
Plutella Xylostella ◽  
Metarhizium Anisopliae ◽  
Chitosan Nanoparticles ◽  
Analytical Techniques ◽  
X Ray ◽  
Synthesis Of Nanoparticles ◽  
Force Microscopy ◽  
Atomic Force ◽  
Afm Analysis

Nanotechnology is increasingly being used in areas of pesticide production and pest management. This study reports the isolation and virulence of a new Metarhizium anisopliae isolate SM036, along with the synthesis and characterization of M. anisopliae–chitosan nanoparticles followed by studies on the efficacy of nanoparticles against Plutella xylostella. The newly identified strain proved pathogenic to P. xylostella under laboratory conditions. The characterization of M. anisopliae–chitosan nanoparticles through different analytical techniques showed the successful synthesis of nanoparticles. SEM and HRTEM images confirmed the synthesis of spherical-shaped nanoparticles; X-ray diffractogram showed strong peaks between 2θ values of 16–30°; and atomic force microscopy (AFM) analysis revealed a particle size of 75.83 nm for M. anisopliae–chitosan nanoparticles, respectively. The bioassay studies demonstrated that different concentrations of M. anisopliae–chitosan nanoparticles were highly effective against second instar P. xylostella under laboratory and semi-field conditions. These findings suggest that M. anisopliae–chitosan nanoparticles can potentially be used in biorational P. xylostella management programs.

scholarly journals Natural and Activated Allophane Catalytic Activity Based on the Microactivity Test in Astm Norm 3907/D3907M-2019

2020 ◽  
Vol 10 (9) ◽  
pp. 3035
Author(s):  
Edward Henry Jiménez Calderón ◽  
Ana Emperatriz Paucar Tipantuña ◽  
Paulina Fernanda Herrera Mullo ◽  
Daniel Alejandro Hidalgo Cháfuel ◽  
Washington Ruiz ◽  
...  
Keyword(s):  
Analytical Techniques ◽  
Bet Surface Area ◽  
Navier Stokes ◽  
Maximum Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Catalytic Activation ◽  
Atomic Force ◽  
Activating Agent

The optimal conditions of the catalytic activation of allophane were evaluated for possible use as a catalyst within a fluidized bed catalytic cracking unit (FCC). The physicochemical properties of natural allophane and activated allophane were studied by using an alkaline activating agent, followed by a hydrothermal treatment. For the characterization, analytical techniques were used: Fourier transform infrared spectroscopy, particle size, (BET) surface area, thermogravimetry (TGA), X-ray diffraction (XRD), chemisorption, X-ray fluorescence (XRF), atomic force microscopy (AFM), and chromatography. The catalytic evaluation was determined by the (MAT) micro activity test equipment constructed according to ASTM D-3907/D3907M-2019. In addition, the Navier–Stokes 3D equations (nonlinear partial derivatives) were studied, which allow studying molecular dynamics contributing substantively to chemical kinetics describing the process of decomposition of crude oil in thermal cracking, determining the maximum temperature at which it retains its properties through the action of heat.

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