Atomic Force Microscopy Techniques Research Articles

Biocidal and antibiofilm activities of arginine-based surfactants against Candida isolates.

Amino-acid-based surfactants are a group of compounds that resemble natural amphiphiles and thus are expected to have a low impact on the environment, owing to either the mode of surfactant production or its means of disposal. Within this context, arginine-based tensioactives have gained particular interest, since their cationic nature-in combination with their amphiphilic character-enables them to act as broad-spectrum biocides. This capability is based mainly on their interactive affinity for the microbial envelope that alters the latter's structure and ultimately its function. In the work reported here, we investigated the efficiency of Nα-benzoyl arginine decyl- and dodecylamide against Candida spp. to further our understanding of the antifungal mechanism involved. For the assays, both a Candida albicans and a Candida tropicalis clinical isolates along with a C. albicans-collection strain were used as references. As expected, both arginine-based compounds proved to be effective against the strains tested through inhibiting both the planktonic and the sessile growth. Furthermore, atomic force microscopy techniques and lipid monolayer experiments enabled us to gain insight into the effect of the surfactant on the cellular envelope. The results demonstrated that all the yeasts treated exhibited changes in their exomorphologic structure, with respect to alterations in both roughness and stiffness, relative to the nontreated ones. This finding-in addition to the amphiphiles' proven ability to insert themselves within this model fungal membrane-could explain the changes in the yeast-membrane permeability that could be linked to viability loss and mixed-vesicle release.

Structural, Magnetic, and Magneto-Optical Properties of Thin Films of BaM Hexaferrite Grown by Laser Molecular Beam Epitaxy.

Thin films of BaM hexaferrite (BaFe12O19) were grown on α-Al2O3(0001) substrates by laser molecular beam epitaxy. Structural, magnetic, and magneto-optical properties were studied using medium-energy ion scattering, energy dispersive X-ray spectroscopy, atomic force microscopy, X-ray diffraction, magneto-optical spectroscopy, and magnetometric techniques, and the dynamics of magnetization by ferromagnetic resonance method. It was shown that even a short time annealing drastically changes the structural and magnetic properties of films. Only annealed films demonstrate magnetic hysteresis loops in PMOKE and VSM experiments. The shape of hysteresis loops depends on thickness of films showing practically rectangular loops and high value of remnant magnetization (Mr/Ms~99%) for thin films (50 nm) and much broader and sloped loops in thick (350-500 nm) films. The magnitude of magnetization 4πMs ≈ 4.3 kG in thin films corresponds to that in bulk BaM hexaferrite. Photon energy and sign of bands in magneto-optical spectra of thin films correspond to ones observed earlier in bulk samples and films of BaM hexaferrite. FMR spectra of 50 nm films at 50 GHz consist of a number of narrow lines. The width of main line ΔH~20 Oe is lower than has been reported up to now.

Investigating the potential of casein as a sustainable material in inhibiting the corrosion of aluminum in hydrochloric acid

AbstractIn this study, the efficiency of casein in inhibiting the corrosion of aluminum in 0.1 M HCl was evaluated. Based on the weight loss data, increasing the amount of casein in the electrolyte from 50 to 500 ppm at 298 K decreased the corrosion rate of aluminum, for instance, from 2.53 to 0.58 g m−2 h−1. It was also demonstrated that with casein, the activation energy of the corrosion phenomenon increased (e.g., from 6.52 kJ/mol without casein to 27.54 kJ/mol with 500 ppm casein). The electrochemical polarization studies illustrated that in the presence of 500 ppm casein, the corrosion current density remarkably decreased from 63.09 to 6.1 µA/cm2. This was compatible with the increase in the charge transfer resistance recorded by electrochemical impedance spectroscopy. Furthermore, the X‐ray photoelectron spectroscopy and atomic force microscopy techniques confirmed the adsorption of casein on the working electrodes, which caused an enhancement in the surface quality of the specimens.

Assessment of nanomechanical properties of Candida albicans as an element of the oral mycobiota in healthy subjects – a preliminary study

Abstract In a healthy physiological state, the mucous membrane of the oral cavity creates a suitable environment for the colonization of Candida spp. yeasts. The aim of the study was to analyze the nanomechanical properties of C. albicans cells derived from the oral cavity of healthy people in a biofilm produced in laboratory conditions. Candida spp. were sampled from the oral cavity of healthy individuals. The process of biofilm formation was analyzed using classic microscopic observation enriched with SEM (scanning electron microscope) and the nanomechanical properties of the cells were assessed with the use of the atomic force microscopy technique (AFM). From all isolated strains in the samples collected of the oral cavity healthy people was detected 79% C. albicans. Other isolated species belonged to the group „non-albicans”. The observations of C. albicans carried out in 24-h cultures revealed a tendency of the cells to form a biofilm structure with multilayer cell systems. The diameter of C. albicans cells in this structure was 5.75 µm, and the length of the pseudohyphae was 17.08 µm. The presence of an extracellular substance surrounding the C. albicans cells was detected. The mean value of the adhesion force determined for C. albicans cells was 4.01 nN. Areas with increased hardness (Force Modulation Mode signal; FMM signal) were found mainly in the zones of cells in contact with the glass substrate. The analysis of Candida cells in liquid samples gives satisfactory results, as it prevents unfavorable changes in the cell surface and thus provides more reliable results. The quality of the biofilm is probably related to the nanomechanical properties of C. albicans cells and may consequently contribute to the stability of the biofilm structures and their susceptibility or resistance to antifungal drugs. The presence of Candida spp. especially in companion animals (dogs, cats) poses a risk of their transmission to the human organism. For this reason, it is advisable to undertake additional research to analyze the ability of zoonotic-origin Candida spp. to form biofilms with comparison of the biofilm-formation capacity of species isolated from humans.

Nanofiber composite for anti-bacterial application by electrospinning technique

The current work aims to study the effect of alumina nanofibers with diameter (3–4 ​nm) added in a weight percentage of 1.3% and 6% to polyacrylamide (C3H5NO)n to improve mechanical properties and thermal stability. Tensile strength, Young's modulus, elongation and toughness were all calculated via tensile test. Thermal properties, including glass transition temperature, thermal energy, and crystallinity of nanocomposites were tested by differential scanning calorimeter (DSC), and Fourier transform infrared spectroscopy (FTIR) was used to characterize chemical bonds in polyacrylamide and alumina nanofibers. The nanocomposite with the added weight percentage of 6% was selected from the above-mentioned percentages upon carrying out the tensile test. It was chosen to be mixed with 1% weight percentage of zinc oxide (ZnO) nanoparticles of diameter 50 ​nm to gain the antibacterial effect, together with good mechanical properties. In addition to the above-mentioned tests, the three-dimensional morphology of the specimens was tested by atomic force microscope technique (AFM), as well as testing against positive and negative gram bacteria to evaluate the efficiency of the prepared nanocomposite as an antibacterial material. Morphological features of samples were tested via Scanning electron microscope (SEM). According to the results, the material exhibited good mechanical and antibacterial properties, making it suitable for use in the production of water filters and antibacterial surfaces used in medical facilities, laboratories and wound dressings.

EIS capacitor sensor, with TiO2 dielectric, applied in the evaluation of phosphate in wastewater

This work presents the development of an Electrolyte-Insulator-Semiconductor (EIS) device with a built-in reference electrode to detect phosphate in wastewater. The idea of developing this device comes from the need to improve the use of water processed by the effluent treatment plant. After treatment process, a fraction of the water can be used as wastewater, this water cannot be consumed, however it can be used for other purposes including cleaning public spaces, such as streets and squares. In the fabrication process of the EIS device, titanium oxide (TiO2) deposited on a silicon substrate was used as a sensor element, and titanium nitride (TiN) was used for the reference electrode. Both materials were deposited by the reactive sputtering process. Aluminum (Al) was used for the electrode on the back of the slide deposited by evaporation. Preliminary results of structural and electrical characterizations indicate that the manufactured device has good sensitivity to phosphate ions (66 mV/ppm). This sensitivity is due to the good quality of the film, which is shown using Raman spectroscopy, atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques, in addition to electrical measurements.

Sol-Gel preparation and wetting behaviour analysis of hydrophobic Zirconium based nano-coating: Implications for solar panel coating

Hydrophobic coatings basically decrease the wettability of surface due to the presence of nanostructures on it. In this research work, nanozirconia sol was prepared by the sol-gel method and further hydrophobically modified using the hexamethyldisilazane (HMDS). Prepared sol was coated on the glass substrate and then analysed for its wetting behaviour. Three samples with different HMDS ratios mixed to Zirconia sol were coated, and analysed for surface morphological parameters through the atomic force microscopy and field emission scanning electron microscopy techniques. The wetting behaviour was analysed by studying the water contact angle and surface free energy of the samples. Here the transmittance was measured by transmittance metre at regular intervals for 30 days. Functional group determination was done by Fourier transform infrared spectrometer that confirmed the formation of Zirconium nanoparticles. Maximum contact angle of 101.2° was observed that showcased the hydrophobic properties. Hydrophobic coating was then successfully prepared, and sample with 2:1 ratio of Zirconium nanoparticles and HMDS showed the best hydrophobic nature amongst all the coatings prepared in this investigation.

Diazenyl derivatives as efficient corrosion inhibitors for mild steel in HCl medium: Gravimetric, electrochemical and computational approach

. In present investigation diazenyl derivatives, namely, (E)-4, 4(E)-4, 4′-(((4-(2-amino-6-phenyl-2H-1, 3-thiazin-4-yl) phenyl) diazenyl) methylene) bis (6-phenyl-6H-1, 3-thiazin 2amine) (ATPA) and (E) 1(4((bis (5-amino1, 3,4- thiadiazol-2-yl) methyl) diazenyl) phenyl) ethanone (ATPE) were synthesized and used as corrosion inhibitor for mild steel (MS) in 15 % HCl solution. Corrosion inhibition studies were performed by weight loss, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization methods. Potentiodynamic polarization result demonstrates that ATPA and ATPE offered inhibition efficiency of 97.11 and 96.02 %, respectively at 200 ppm concentration and 303 K temperature. Calculated standard free energy of adsorption values were found in the range of −38.47 to −40.84 kJmol−1 for ATPA and −36.91 to −39.19 kJmol−1 for ATPE, suggesting the mixed type adsorption of ATPA and ATPE on MS surface. The adsorption of ATPA and ATPE on MS surface obeyed Langmuir adsorption isotherm. Morphological analysis performed on uninhibited and inhibited samples by field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), atomic force microscopy(AFM)and X-ray photoelectron spectroscopy(XPS) techniques suggested the formation of protective layer of inhibitor molecules on MS surface. According to polarization results, both compounds behave as anodic inhibitors. Theoretical data of ATPA and ATPE obtained from Density functional theory (DFT), Monte Carlo simulation (MCS) and Molecular dynamic simulation (MDS) supports the experimental observations.

Electrochemical and quantum chemical investigation to evaluate corrosion inhibition performance of therapeutic drug

ABSTRACT The therapeutic drug Kanamycin (KYN) was applied as a possible green inhibitor for the corrosion mitigation of mild steel (MS) in 0.5 N HCl. Electrochemical techniques, quantum chemical calculations along with kinetic and thermodynamic parameters were evaluated. Kanamycin showed maximum efficiency of 80 % for the concentration of 1000 ppm in 0.5 M HCl at 303 K. Efficiency of the inhibitor decreased with an increase in temperature. The adsorption of KYN on mild steel was through physisorption and followed Langmuir adsorption isotherm. Experiment findings were supported by computational studies using Density Functional Theory (DFT) calculations. The surface study was performed by scanning electron microscope (SEM), Energy Dispersive X-ray (EDS), and “Atomic Force Microscope (AFM) techniques. FT-IR and XRD studies were done to reaffirm the adsorption of inhibitor. These calculations were useful in predicting the mechanistic aspects of corrosion. KYN emerged as an efficient green inhibitor with environmental benefits.

Scanning Tunneling Microscopy as a Method for Analyzing the Correlation of Local Resistive and Ferroelectric Properties in Memristive Compositions

The creation of multilayer resistive memory devices based on nanolayer memristive compositions with thin ferroelectric (FE) films, in which resistance switching is caused by a combination of effects related to the influence of interface regions, polarization states, charge transport mechanisms, and microscopic features of nanostructures, requires the development of new experimental approaches to the study of local electrophysical properties. One of the most common ways to investigate local electrophysical properties is the use of various atomic force microscopy (AFM) techniques, including the Kelvin probe microscopy, tunneling AFM, and piezoresponse AFM. The main reason for switching from AFM to scanning tunneling microscopy techniques when studying the local resistive properties of memristive compositions with FE films is the need to stabilize the probe-sample contact. The main obstacle to the effective use of AFM techniques to study the local ferroelectric properties in nanolayer memristive compositions with thin FE films is the occurrence of a strain gradient during scanning, which leads to the contribution of the flexoelectric effect and direct piezoelectric effect in the measurement results. In this work, we have developed a method of investigating the local FEproperties using scanning tunneling microscopy (STM) and spectroscopy (STS) techniques under ultra-high vacuum conditions. The essence of the proposed approach is to identify the contribution of polarization charges, as well as the features of their screening on the free surface of the FE film, to the results of STS measurements at different polarization orientations in the FE film. In combination with STM measurements of local morphological features, the analysis of experimental results makes it possible to identify the state of FE polarization, determine the contribution of the surface screening of polarization charges to the manifestation of memristive effects, and investigate the correlation between the local resistive and FE properties in nanolayer memristive compositions with thin FE films.

Current and deformation induced by voltage in the single LiNi0.8Co0.1Mn0.1O2 particle from atomic force microscopy technique and phase field simulation

One of the key factors affecting lithium-ion battery electrode materials’ efficiency is the process of lithiation and delithiation. Studies of the electrochemical behavior of Ni-rich active electrode materials at the nanoscale have largely been focused on macroscopic measurements, but few have investigated the intrinsic microscopic mechanism underlying their failure. In this paper, lithium-ion diffusion current and surface deformation of single LiNi0.8Co0.1Mn0.1O2 (NCM811) nanoparticles under external electric fields were measured by atomic force microscopy (AFM) techniques. Then, the current and deformation of NCM811 single particle under the applied voltage were simulated by phase field method to analyze electrochemical behaviors of the particle from experiments based on the electrochemical-mechanical coupled model. The simulation results revealed that the change of lithium-ion concentration and stress in particles are the factors leading to the evolution of current and deformation under applied voltage observed by AFM.

Trianthema portulacastrum leaf extract mediated synthesis of silver nanoparticles and elucidation of their larvicidal and antibacterial activities

The current study aims to evaluate the larvicidal and antibacterial capabilities of silver nanoparticles generated utilizing the aqueous leaf extract of Trianthema portulacastrum (TP-AgNPs). The synthesis of silver nanoparticles (TP-AgNPs) via Trianthema portulacastrum extract synthesis was validated using UV–vis spectroscopy, FTIR, XRD, and Atomic Force Microscopy techniques. In particular, Aedes aegypti, the dengue vector mosquito, and Culex quinquefasciatus, the malaria vector mosquito, were subjected to larvicidal bioassays in various doses of TP-AgNPs and T. portulacastrum crude aqueous leaf extract in third instar larvae. Using TP-AgNPs, a significant larvicidal impact was observed in Cx. quinquefasciatus at 24 and 48 h (LC50 of 6.49 and 4.50 ppm, respectively). TP-AgNPs was proven to be an effective larvicide for the control of malaria and dengue vectors. Additionally, Klebsiella pneumoniae growth was significantly suppressed by TP-AgNPs. The antibacterial results show that all bacterial pathogens tested were effectively inhibited. TP-AgNPs exhibit excellent larvicidal and antibacterial properties, making them a promising and environmentally friendly biocontrol tool against dengue and malarial vectors.

Biopolymer and its nanoparticles for surface coating enhancement of epoxy primer on zinc: electrochemical and surface studies

ABSTRACT The purpose of the current work is to develop an eco-friendly formulation which can be successfully utilised to mitigate zinc corrosion in marine environments. Biopolymer amylopectin and its nanoparticles were used to improve the coating characteristics of epoxy primer on zinc. Amylopectin nanoparticles (AMP-Np) were prepared by the microwave-assisted nanoprecipitation method and characterised using XRD, ATR-FTIR, and TEM studies. Inhibition studies were performed to achieve the optimum inhibitor concentration required for corrosion inhibition of zinc in 3.5% NaCl. Detailed surface morphology was studied using scanning electron microscopy and atomic force microscopic techniques. The overall efficiency of the coating after incorporating AMP (0.02 gL−1) was found to be 99.5%. With the addition of AMP-Np (0.005 gL−1), 99.9% coating efficiency was attained by reducing the concentration to 1/4th of AMP. The epoxy-coated metal coupons, along with micro and nano AMP, were dipped in 3.5% NaCl for 15 days to mitigate corrosion of zinc.

Preparation of open tubular capillary column covalently coated with polystyrene sulfonate with 4,4'-azobis (4-cyanopentanoyl chloride) as polymerization initiator for electrochromatographic separation of alkaloids, sulfonamides and peptides.

An open tubular capillary electrochromatography column covalently bonded with polystyrene sulphonate was prepared via in situ polymerization using functionalized azo-initiator 4,4'-Azobis(4-cyanopentanoyl chloride). Scanning electron, fluorescence and atomic force microscopy techniques showed the formation of a relatively rough layer of polymer. In addition, -CN and C = O stretching vibrations from infrared spectroscopy proved the successful immobilization of the azo-initiator through covalent bonding and X-rayPhotoelectronSpectroscopy confirmed the elemental composition of the formed polymer layer. The prepared column was found to be appropriate for small and medium-sized molecules separation. Compared to bare fused silica capillary column higher selectivity and resolution were obtained for the separation of alkaloids, sulfonamides and peptides as a result of the electrostatic and pi-pi stacking interactions between the small organic molecules and the coated column without compromising the electroosmotic flow mobility. Separation efficiency was also increased compared to the bare capillary for the separation of alkaloids (about 1.5 times). Moreover, intraday, inter day, intra batch and inter batch relative standard deviation values of retention time and peak area of peptides were within 2% and 10%, respectively, indicating a good repeatability of the column preparation procedure. The developed method for the covalent bonding of polymers through a functionalized azo-initiator could represent a promising stable method for the preparation of open tubular column. This article is protected by copyright. All rights reserved.

Abstract 5477: An investigation to study differential gene expression of lung cancer cells, tumor associated macrophages, and bone marrow derived mesenchymal stems cells in the tumor microenvironment

Abstract Cancer is a public health crisis affecting approximately 19.3 million globally, annually. Lung cancer has the highest percentage of incidence and is responsible for 27% of cancer-related deaths. The prevalence of lung cancer worldwide led us to investigate differential gene expression in lung adenocarcinoma and small cell lung cancer cell lines in comparison to a healthy lung cell line. We also investigated the effect of lung tumor microenvironment to bone marrow derived pluripotent mesenchymal stem cells (PMSC) and tumor associated macrophages. This research involved cancer and healthy cell line culture with appropriate medium. Whole transcriptomic and small non-coding RNA sequencing and analysis by Ingenuity Pathway Analysis (Qiagen, USA), Quantitative RT-PCR and ELISA assays. We further studied morphological changes and differential gene expression in extracellular vesicles(exosomes) isolated from the TAM and TME exposed PMCs by atomic force microscopy and RNA sequencing techniques. The results of our investigation showed differential gene expression and novel core canonical pathways in the lung cancer cells, TME exposed TAM, and PMSC. We also observed morphological changes in TME derived exosomes from TAM and PMSC. RNA sequencing results showed differential gene expression of both coding and non-coding RNAs including tRNA fragments. Thus, our findings of this investigation led to identification of multiple cancer related genes and small non-coding microRNA, long non-coding RNA, and tRNA fragments which will have potential diagnostic and therapeutic target value that demands further future research. Acknowledgement: This research is supported by a grant from US NIH-NIGMS- 5T34GM100831-08 and US-NIH Grant# U 54 MD007597-31-5959. Citation Format: Hirendra N. Banerjee, Joseph Hedley, Cheslsey Aurelus, Narendra Banerjee, Kuldeep Rawat, Quentin Reaves, Shennel Brown, Darla Gilmartin, Makieyah Liverman, Jazmine Cuffee, Elizabeth Cagle, Erik Armstrong, Brent Lake, Santosh Mandal, Somiranjan Ghosh, Stephen Beebe, Kamal Asadipour, Christopher Krauss, Santanu Bhattacharya, Tanmay Kulkarni, Zahidur Abedin. An investigation to study differential gene expression of lung cancer cells, tumor associated macrophages, and bone marrow derived mesenchymal stems cells in the tumor microenvironment. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5477.

Mechanical Properties and Thermal Shock Behavior of Al2O3-YSZ Ceramic Layers Obtained by Atmospheric Plasma Spraying

Ceramic coatings have many advantages for industrial and medical applications due to their exceptional properties. Ceramic coatings with a thickness of approximately 45 μm, after grinding, were grown using a robotic arm that used the atmospheric plasma spraying procedure. The thermal shock stresses—a common situation in applications but difficult to reproduce under laboratory conditions—of the ceramic layers on top of the metal substrate was achieved using solar energy focused by a concentrating mirror, based on experiments conducted in the CNRS-PROMES laboratory, UPR 8521, belonging to the French National Centre for Scientific Research (CNRS). The ceramic layers showed excellent stability at 1000 °C, even at high heating or cooling rates. At high temperatures (above 1800 °C), the exfoliation of the complex ceramic layer was observed. No differences in the structural, phase, mechanical or adhesion properties of the ceramic layer were observed after the thermal shock cycles (in the literature, there have been quite few reports regarding the properties of the ceramic layers after the thermal shock application). Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques were used to characterize the complex ceramic coating and the effects of thermal shock cycling. The phases and chemical composition of the complex coatings remained similar, insensitive to thermal shock at 1000 °C, consisting of a mixture of crystalline yttrium zirconium oxide and α and γ alumina. For all cases, the main residual stress state was tensile. After 5 or 10 cycles of thermal shocks, a smoothing of the residual stress state was observed in the investigated area. A higher temperature (above 1800 °C), applied as thermal shock, led to higher residual stresses and resulted in large cracks and the spallation of the coating layer.

Ultrafast lithium disilicate veneer debonding time assisted by a CO2 laser with temperature control

We report on using a CO2 (10.6 µm) laser to debond the lithium disilicate veneers. Sixty-four sound human premolar teeth and 64 veneer specimens were used in the study. The zigzag movement via CO2 laser handpiece along with an air-cooled jet to prevent temperature elevation above the necrosis temperature limit (5.5 C°) was applied. The optimal deboning irradiation time was super-fast, at about 5 seconds at 3 Watt CO2 laser power. It is 20 times less than any previously published work for veneers debonding. The enamel beneath the debonded veneers has been assessed by atomic force microscopy (AFM) and shear stress technique as criteria for the easiness of debonding. The fast deboning process with nonsignificant changes in enamel integrity and tooth vitality reflects the high potential of CO2 laser in veneers debonding.

Synthesis, spectroscopic analysis and electrochemical studies of novel organic compound based on N-alkylphthalazinone chemistry as corrosion inhibitor for carbon steel in 1M HCl

The adsorption affinity and corrosion protection of two synthesized N-alkylphthalazinone derivatives 2(a-b), namely: 2-(prop-2-yn-1-yl)-4-(p-tolyl)phthalazin-1(2H)-one (a) and 4-(4-chlorophenyl)-2-(prop-2-yn-1-yl)phthalazin-1(2H)-one (b) on carbon steel (CS) in an acidic environment using electrochemical and mass loss methods. The mass loss test at the highest inhibitor concentration produced a maximum corrosion efficiency of 93.4% for inhibitor (a). Thermodynamic parameters were determined while the inhibitors' adsorption process was investigated. The inhibitory molecules adsorption on the CS substrate accompanied the Langmuir isotherm. As a function of inhibitor concentration, the thermodynamic activation functions of the dissolution process were calculated. Surface examination such as scanning electron microscopy (SEM), fourier transfer infrared spectroscopy (FTIR), and atomic force microscopy (AFM) techniques were used to confirm the adsorption phenomenon. Also investigated were quantum chemical parameters to approve the donor-acceptor system of the synthesized N-alkylphthalazinone derivatives. The theoretical values are in good correlation with the experimental values.

Comparative radiosensitization efficiency assessment of graphene oxide and Ti3C2 MXene as 2D carbon-based nanoparticles against breast cancer cells: characterization, toxicity and mechanisms

The efficacy of two carbon-based nanomaterials, graphene oxide (GO) and Ti3C2 MXene (MX), on the radiosensitivity of the breast cancer cells (BCCs) was investigated using clinical x-ray irradiation. The prepared GO and MX nanoparticles (NPs) were firstly characterized utilizing Fourier transform infrared, ultraviolet–visible, atomic force microscopy and transmission electron microscopy techniques and subsequently assessed in terms of their radiobiological properties. The results of the cell toxicity assay indicated that neither NPs exhibited significant cytotoxicity after 48 h incubation with BCC up to 50 µg ml−1 concentration without irradiation. The cell internalization results showed an approximately equivalent cellular uptake for both NPs after 6 h incubation with BCC. Our comparative studies with radiotherapy demonstrated that both NPs substantially increased cell proliferation inhibition and cell apoptosis of BCC under x-ray irradiation when compared to BCC treated with irradiation alone. Additionally, the 2ʹ,7ʹ-dichlorofluorescin diacetate flow cytometry results and fluorescent microscopy images revealed that both NPs remarkably increased the level of intracellular reactive oxygen species (ROS) generation in BCC under x-ray irradiation. The MX nanosheets exhibited superior radiosensitization efficiency than GO under x-ray irradiation due to its higher level of intracellular ROS generation (MX = 75.2% and GO = 65.2%). Clonogenic cell survival assay and extracted radiobiological parameters revealed that both NPs in combination with x-ray irradiation induced more lethal damage and less sublethal damage to BCC. Generally, the obtained results demonstrate that the MX NPs, as a stronger radiosensitizer than GO, could be a promising candidate for enhancing the effectiveness of radiotherapy in breast cancer treatment.

Identification of Supramolecular Structures of Porphyrin Polymer on Single-Walled Carbon Nanotube Surface Using Microscopic Imaging Techniques

Although the supramolecular structure of porphyrin polymers on flat surfaces (i.e., mica and HOPG) has been extensively studied, the self-assembly arrays of porphyrin polymers on the SWNT (as curved nanocarbon surfaces) have yet to be fully identified and/or investigated, especially using microscopic imaging techniques, i.e., scanning tunneling microscopy (STM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). This study reports the identification of the supramolecular structure of poly-[5,15-bis-(3,5-isopentoxyphenyl)-10,20-bis ethynylporphyrinato]-zinc (II) on the SWNT surface using mainly AFM and HR-TEM microscopic imaging techniques. After synthesizing around >900 mer of porphyrin polymer (via Glaser-Hay coupling); the as-prepared porphyrin polymer is then non-covalently adsorbed on SWNT surface. Afterward, the resultant porphyrin/SWNT nanocomposite is then anchored with gold nanoparticles (AuNPs), which are used as a marker, via coordination bonding to produce a porphyrin polymer/AuNPs/SWNT hybrid. The polymer, AuNPs, nanocomposite, and/or nanohybrid are characterized using 1H-NMR, mass spectrometry, UV-visible spectroscopy, AFM, as well as HR-TEM measuring techniques. The self-assembly arrays of porphyrin polymers moieties (marked with AuNPs) prefer to form a coplanar well-ordered, regular, repeated array (rather than wrapping) between neighboring molecules along the polymer chain on the tube surface. This will help with further understanding, designing, and fabricating novel supramolecular architectonics of porphyrin/SWNT-based devices.