Atomic Force Microscopy Studies Research Articles

Effect of CTAB on the aggregation properties of Congo Red organized in layer-by-layer electrostatic self-assembled film: a spectroscopic and Atomic force microscopy study

Effect of CTAB on the aggregation properties of Congo Red organized in layer-by-layer electrostatic self-assembled film: a spectroscopic and Atomic force microscopy study

A methodical investigation on stilbazolium derivative substituted with 2,4-Dichlorobenzaldehyde as a donor: An effective crystal for optical device fabrication

For a couple of decades, nonlinear optics (NLO) has garnered significant attention due to its widespread application in optical systems. In this viewpoint, a new 2-[2(2,4-Dichloro-phenyl)vinyl]methyl-1-pyridinium iodide (DCPI) crystal was grown through slow evaporation process for NLO application. Single Crystal X-ray diffraction (SCXRD) study reveals that the DCPI crystallized centrosymmetric (P-1) space group. The CHN elemental analysis and NMR spectroscopy assess the purity of the material. The vinyl (CC) group formation in DCPI was asserted by the Fourier-transform infrared (FT-IR) spectrum. The Hirshfeld surface analysis confirms the presence of hydrogen bonds in the crystal structure through its contribution percentage (27 %) to the overall intermolecular interaction. DCPI crystal exhibits 80 % transparency in the visible region. Luminescence studies assess the green light-emitting characteristics of the DCPI crystal. The etching and Atomic Force Microscopy (AFM) studies confirm that the DCPI crystal has a flat surface with minimum dislocations. Z-scan studies found the third-order nonlinear characteristics of the crystal. Overall, the article illustrates the appropriateness of DCPI crystal in fabricating optical devices through its significant optical characteristics.

Mechanical properties of shale during pyrolysis: Atomic force microscopy and nano-indentation study

Quantitative characterization of the geo-mechanical properties of shale and organic matter (OM) holds paramount significance in the assessment of shale gas reserves and the design of hydraulic fracturing. However, the mechanical evolution processes during shale hydrocarbon generation and its influencing factors have received limited attention. This study examines the changes in shale mechanical properties during pyrolysis at high temperatures (415–600 °C) and high pressure (50–125 MPa) for mature to over-mature stages. The nanoindentation and in-situ AFM-QNM analysis are utilized to characterize the changes in mechanical properties during evolution. Subsequently, gas adsorption, Fourier Transform infrared spectroscopy (FTIR), and laser Raman spectroscopy (Raman) are used to investigate the factors influencing the mechanical properties of shale and the associated OM, and establish a model for the evolution of the mechanical properties. The results demonstrate that with increasing maturity, the overall Young's modulus of the bulk shale gradually increases from 42.8 GPa to 58.4 GPa for the temperature increment from 415 °C to 600 °C. During the thermal maturation process, the mesopore structure and quartz content of the shale significantly influence its mechanical properties. Young's modulus of OM shows an S-shaped trend, with variations in the micromechanical properties of OM corresponding to stages of hydrocarbon generation. In particular, two peaks of Young's modulus increase are observed during the mature and over-mature stages. In the mature stage, the aromatization of the kerogen leads to substantial detachment of aliphatic side chains and oxygenated functional groups, resulting in a higher degree of aromatization. This reduces the kerogen spacing and consequently increases the Young's modulus. In the over-matured stage, the process of aromatics condensation leads to the orientation and arrangement of aromatic rings, reducing the number of key site vacancies and crystal defects, thereby forming large aromatic clusters and significantly increasing the graphite-like structure. This study will facilitate the analysis of shale matrix deformation mechanisms at the microscale, providing a fundamental theoretical and scientific basis for shale fracturing design, exploration, and development.

Achieving the 1D Atomic Chain Limit in Van der Waals Crystals.

Experiments with graphene have demonstrated that 2D van der Waals materials can be stable, robust, and efficiently manipulated at the level of individual atomic planes. However, the stability and manipulation of 1D van der Waals materials and individual atomic chains remains elusive. Here, the ability to exfoliate and process two representative van der Waals materials containing 1D motifs, namely MoI3 and Ta2Se8I, at the scale of individual atomic chains is demonstrated. High-resolution transmission electron microscopy and atomic force microscopy studies confirm the presence of stable individual atomic chains of MoI3 at room temperature. It is further shown that 1D van der Waals materials with low exfoliation energy, such as Ta2Se8I, can be processed with electron beams to achieve suspended individual atomic chains. Ab initio calculations corroborate the findings regarding the cleavage energies and the thermodynamic stability of individual atomic chains in these 1D van der Waals materials. These results demonstrate that the top-down approach in material processing can be extended to the scale of individual chains.

Enhancement of dielectric constant in Sm:Zr co-doped HfO2 films synthesized by cost-effective method

Sm, Zr co-doped HfO2 films were deposited on a p-type silicon wafer using a cost-effective spin coating method. The influence of Sm, Zr co-doping concentration variation on structural, compositional, morphological, and electrical properties was examined. The dominance of the orthorhombic phase (o-phase) in comparison to the monoclinic phase was noted to rise with the simultaneous increment of Sm doping concentration and decrement of Zr concentration. A decrease in oxygen vacancies was noted for all the Sm, Zr co-doped HfO2 films from XPS results. Nonporous and uniform distribution of grains was observed from Field Emission Scanning Electron Microscope (FESEM) and Atomic Force Microscopy (AFM) studies. Electrical studies of MOS capacitors based on Sm, Zr co-doped HfO2 films revealed a low leakage current. C-V studies exhibited an increment of dielectric constant and a decrement of interface trap densities. Further, to obtain insights into the microscopic features of Sm, Zr co-doped films, impedance and modulus studies have been performed. The obtained results imply the potential of tuning Sm, Zr co-doping concentrations in HfO2 towards stabilization of the orthorhombic phase and to enhance the dielectric constant of the films.

Complementary correlation between surface microbubble and droplet shapes

Previous atomic force microscopy studies have suggested that surface micro- and nanobubbles exhibit a flat shape. In this study, we directly observed surface microbubbles formed in an NH3BH3 solution using an optical microscope. No flat microbubbles were observed. Instead, on an SiO2/Si substrate, we discovered a relationship where the sum of the contact angle of a microbubble and the contact angle of a droplet equaled ∼180°. This relationship allowed us to control the shape of surface microbubbles by manipulating the wettability of the surface and the surface tension of the liquid, similar to droplet control. We were able to produce almost perfectly spherical microbubbles. Conversely, on a Cu foil, this relationship did not hold, although we still observed the formation of nearly spherical microbubbles. In this scenario, the shape of microbubbles appeared to be influenced by contact line pinning.

Automated High-Throughput Atomic Force Microscopy Single-Cell Nanomechanical Assay Enabled by Deep Learning-Based Optical Image Recognition.

Mechanical forces are essential for life activities, and the mechanical phenotypes of single cells are increasingly gaining attention. Atomic force microscopy (AFM) has been a standard method for single-cell nanomechanical assays, but its efficiency is limited due to its reliance on manual operation. Here, we present a study of deep learning image recognition-assisted AFM that enables automated high-throughput single-cell nanomechanical measurements. On the basis of the label-free identification of the cell structures and the AFM probe in optical bright-field images as well as the consequent automated movement of the sample stage and AFM probe, the AFM probe tip could be accurately and sequentially moved onto the specific parts of individual living cells to perform a single-cell indentation assay or single-cell force spectroscopy in a time-efficient manner. The study illustrates a promising method based on deep learning for achieving operator-independent high-throughput AFM single-cell nanomechanics, which will benefit the application of AFM in mechanobiology.

Coumarin derivatives as new anti-biofilm agents against Staphylococcus aureus

Staphylococcus aureus infections are the primary causes of morbidity, and mortality, particularly in immuno-compromised individuals. S. aureus associated infections are acquired from community, as well as hospital settings, and difficult to treat because of the emerging resistance against available antibiotics. One of the key factors of its resistance is the biofilm formation, which can be targeted to treat S. aureus-induced infections. Currently, there is no drug available that function by targeting the biofilm. This unmet need demands the discovery of drug candidates against S. aureus biofilm. The present study was designed to evaluate coumarin derivatives 1–21 against S. aureus biofilm. The 96-well plate crystal violet assay was employed for the quantification of biofilm. Results showed that the coumarin derivatives 2–4, 10, and 17 possess potent antibiofilm activity, with MBIC values between 25–100 μg/mL. The results were further confirmed through atomic force microscopy (AFM), scanning electron (SEM), and fluorescence microscopic studies. The quantitative RT-PCR analysis revealed the downregulation of biofilm associated genes, icaA and icaD. These coumarin derivatives were also found to be non-cytotoxic to fibroblasts. This study, therefore, identifies the antibiofilm potential of coumarin derivatives that will pave the way for further research on these derivatives.

An alternative approach in the synthesis of strontium-hydroxyapatite and strontium hydroxyapatite embedded in graphitic carbon nitride nanocomposites for potential tissue engineering applications

Sr-hydroxyapatite has drawn much attention with promising applications in biomedical engineering especially in drug delivery and tissue repair. A novel protocol for the preparation of Strontium hydroxyapatite (Sr-HAP) and Strontium hydroxyapatite encapsulated by graphitic carbon nitride (Sr-HAP@gCN) with high purity and better homogeneity was adopted for potential use in orthopaedic surgeries. The physiological pathway of Strontium and calcium inside humans follow the same trend leading to the mineral deposition of the bone. In the present study, a novel attempt in synthesizing Sr-HAP and Sr-HAP@gCN by the hydrothermal method is proposed for obtaining an ideal biomaterial with potential biocompatibility and pharmacological activity. Phase identification by X-ray diffraction (XRD), Fourier transform Infra-Red spectroscopic analysis (FTIR), Electron & atomic force microscopic studies, Thermogravimetric and Raman spectroscopic analysis was performed on the prepared Sr-HAP and Sr-HAP@gCN to characterize the incorporation efficiency of Strontium. Resazurin microtiter assay and MTT assay were used to evaluate antimicrobial susceptibility and biocompatibility. The typical crystal phase of Sr-HAP and a phase change in Sr-HAP@gCN have been demonstrated with special reference to the interfacial connection between gCN and Sr-HAP through FT-IR studies. Raman spectroscopy revealed the archetypal signature of symmetric and asymmetric PO vibrations pertaining to linearity change with the addition of Strontium. The biological effect of Sr-HAP and Sr-HAP@gCN was quite significant in inducing mineralization when kept immersed in simulated body fluid (SBF) for 21 days. Promising results pertaining to antimicrobial susceptibility and biocompatibility have been proved as an encouraging choice for drug delivery applications and bone filling applications.

Molecular-level studies of extracellular matrix proteins conducted using atomic force microscopy.

Extracellular matrix (ECM) proteins provide anchorage and structural strength to cells and tissues in the body and, thus, are fundamental molecular components for processes of cell proliferation, growth, and function. Atomic force microscopy (AFM) has increasingly become a valuable approach for studying biological molecules such as ECM proteins at the level of individual molecules. Operational modes of AFM can be used to acquire the measurements of the physical, electronic, and mechanical properties of samples, as well as for viewing the intricate details of the surface chemistry of samples. Investigations of the morphology and properties of biomolecules at the nanoscale can be useful for understanding the interactions between ECM proteins and biological molecules such as cells, DNA, and other proteins. Methods for preparing protein samples for AFM studies require only basic steps, such as the immersion of a substrate in a dilute solution or protein, or the deposition of liquid droplets of protein suspensions on a flat, clean surface. Protocols of nanolithography have been used to define the arrangement of proteins for AFM studies. Using AFM, mechanical and force measurements with tips that are coated with ECM proteins can be captured in ambient or aqueous environments. In this review, representative examples of AFM studies are described for molecular-level investigations of the structure, surface assembly, protein-cell interactions, and mechanical properties of ECM proteins (collagen, elastin, fibronectin, and laminin). Methods used for sample preparation as well as characterization with modes of AFM will be discussed.

Effect of cetyl pyridinium chloride on corrosion inhibition of mild steel in acidic medium

The corrosion inhibition behavior of cetyl pyridinium chloride (CPC) on mild steel (MS) in 0.5 M H2SO4 solution was examined using weight loss and potentiodynamic polarization method. Different concentrations of CPC (0.000192 M, 0.0038 M, 0.0057 M and 0.0077 M) was used to find the balanced CPC in the acid solution. Among them, 0.000192 M and 0.0077 M of CPC solution showed a corrosion rate of 8.23×10−3, 3.52×10−5 (mm/Year), and the inhibition efficiency of 89.94 % and 96.23 %, respectively, which is lower than the pure acidic solution (0.5 M H2SO4). Furthermore, the experimented MS surfaces were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), and Atomic Force Microscopy (AFM). FESEM and AFM studies demonstrated the corrosion attack on the MS surface, which is relatively less as compared to the only acid-exposed surface. The SEM-EDX analysis indicates the presence of nitro-group on the MS surface, which might be due to the contribution of pyridinium protonation of CPC. This phenomenon might enhance the corrosion resistance on the MS surface.

Hydrothermal synthesis of cadmium sulfide decorated reduced graphene oxide photocatalyst for the degradation of photostable naphthol blue black dye

Photocatalysis is being used for the mineralization of recalcitrant organic pollutants in water that cannot be treated with conventional methods. Cadmium sulfide decorated reduced graphene oxide (rGO-CdS) nanocomposite photocatalyst was synthesized by hydrothermal method and evaluated for the removal of a photostable textile azo dye, naphthol blue black (NBB) under ultraviolet light (UV-A, 365 nm). The rGO-CdS combination was opted for due to utilizing the narrow band gap (Eg = ~2.4 eV) of CdS and robust rGO support, capable of attracting organic pollutants to surface, bear, and protect CdS from photocorrosion. The formation of rGO-CdS was proved from the findings of physiochemical characterization UV–visible-, X-ray diffraction photoelectron, Raman, energy dispersive X-ray-spectroscopic, and scanning, transmission electron, and atomic force microscopic studies. The spherical CdS was decorated on the random shaped rGO sheets. Eg of CdS and rGO-CdS were 2.42 and 2.39 eV, respectively. After 2 h of light exposure, 2 g/L of rGO-CdS mineralized 95 % of NBB (2 × 10−4 mol/L). After 5 cycles, 80 % of photocatalytic efficiency was retained. In gas chromatography-mass spectrometry studies, 8 fragments of NBB were found after 1 h and confirmed that the degradation was mediated by photocatalytic dilapidation. The optimum pH for NBB degradation was 9. The rGO-CdS was found to be a potentially stable and reusable photocatalyst for environmental applications.

Environmental Influence on Stripe Formation at the Graphite-Water Interface.

Understanding characteristics of graphite-water interface is of scientific significance and practical importance. Ordered stripe structures have been observed at this interface, with their origins debated between condensed gas molecules and airborne hydrocarbons. Atomic force microscopy (AFM) studies have revealed variations in the morphology, formation and growth of these ordered structures. Here, we investigate the graphite-water interface under different environmental conditions using PeakForce Quantitative Nanomechanical (PF-QNM) AFM. Our findings reveal that stripe structures with 4 nm width and 0.5 nm periodicity, form and grow under wet laboratory conditions but not in pure inert gas or cleanroom environments. These stripes appear more readily when the graphite surface is immersed in water, with growth associated with gas nanodomains on the surface. This suggests that atmospheric contaminants migrate to the water-graphite interface, potentially facilitated by gas states. These findings underscore the impact of environmental conditions on graphitic materials, providing new insights into the mechanisms underlying stripe formation and growth.

Comparative Evaluation of Surface Roughness of Different Rotary Nickel-Titanium (NiTi) Files After Autoclaving: An Atomic Force Microscopic Study.

Introduction Canal preparation is a critical step in endodontic therapy. Introducing nickel-titanium (NiTi) rotary instruments has significantly reduced the likelihood of errors in curved canals. However, due to their price, these instruments are often reused following autoclaving. The aim of this study is to compare and evaluate the surface characteristics of two designs of rotary NiTi files used in curved canals and subjected to multiple autoclaving cycles, utilizing an atomic force microscope for detailed analysis. Methods A total sample size of 24 files was taken, 12 files of Hyflex EDM (Coltene/Whaledent, Germany) files andWaveOne Gold (Dentsply Sirona, USA) fileswere then divided into four groups (n=6) as follows:Group I: Hyflex EDM control group;Group II: WaveOne Gold control group;Group III: Hyflex EDM experimental group; Group IV: WaveOne Gold experimental group. Sterilization using an autoclave was performed thrice for Groups I and II files. The files in Groups III and IV were used in simulated curved canals three times and autoclaved after each use. Atomic force microscopy was used to assess the surface roughness of the files after the first and third autoclave cycles. Results The results showed that, without statistical significance, Hyflex EDM exhibited the highest surface roughness after the first usage among the two file systems. Conclusion It can be concluded that both Hyflex EDM and WaveOne Gold files produced similar levels of surface changes when subjected to multiple usage and autoclaving cycles.

Physico-Chemical Properties of Copper-Doped Hydroxyapatite Coatings Obtained by Vacuum Deposition Technique.

The hydroxyapatite and copper-doped hydroxyapatite coatings (Ca10-xCux(PO4)6(OH)2; xCu = 0, 0.03; HAp and 3CuHAp) were obtained by the vacuum deposition technique. Then, both coatings were analyzed by the X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and water contact angle techniques. Information regarding the in vitro antibacterial activity and biological evaluation were obtained. The XRD studies confirmed that the obtained thin films consist of a single phase associated with hydroxyapatite (HAp). The obtained 2D and 3D SEM images did not show cracks or other types of surface defects. The FTIR studies' results proved the presence of vibrational bands characteristic of the hydroxyapatite structure in the studied coating. Moreover, information regarding the HAp and 3CuHAp surface wettability was obtained by water contact angle measurements. The biocompatibility of the HAp and 3CuHAp coatings was evaluated using the HeLa and MG63 cell lines. The cytotoxicity evaluation of the coatings was performed by assessing the cell viability through the MTT assay after incubation with the HAp and 3CuHAp coatings for 24, 48, and 72 h. The results proved that the 3CuHAp coatings exhibited good biocompatible activity for all the tested intervals. The ability of Pseudomonas aeruginosa 27853 ATCC (P. aeruginosa) cells to adhere to and develop on the surface of the HAp and 3CuHAp coatings was investigated using AFM studies. The AFM studies revealed that the 3CuHAp coatings inhibited the formation of P. aeruginosa biofilms. The AFM data indicated that P. aeruginosa's attachment and development on the 3CuHAp coatings were significantly inhibited within the first 24 h. Both the 2D and 3D topographies showed a rapid decrease in attached bacterial cells over time, with a significant reduction observed after 72 h of exposure. Our studies suggest that 3CuHAp coatings could be suitable candidates for biomedical uses such as the development of new antimicrobial agents.

Greening the composite industry: Evaluating Lantana camara Verbenaceae fiber as a promising substitute for lightweight polymer matrix composites

Presently, researchers are engaged in investigations with the aim of developing novel products that exhibit biodegradability and subsequent environmental friendliness. As products, biofiber-based composites are gaining popularity in various industries. Consequently, this investigation successfully identified a unique cellulosic stem fiber from Lantana camara L. (Verbenaceae) plant. As the fiber was unique, sustainable, and abundantly available throughout all seasons, it was selected for the comprehensive characterization investigation to find its potential use as a lightweight bio-based composite material substitute for synthetic fibers. Physiochemical examination revealed that the Lantana camara Verbenaceae fiber had a greater cellulose concentration (61.23±8.42 %) and density (1167±60 kg/m3), measured to be very less compared to synthetic fiber, making a perfect choice for producing lightweight composites with higher strength. The presence of cellulose Iβ and the ordered character of the crystallites were verified by Fourier transform infrared spectroscopy and X-ray diffraction method. Thermogravimetric study showed the maximum degradation temperature of 323 °C, a thermal stability of 242 °C, and a kinetic activation energy of 66.11 kJ/mol. The maximum tensile strength, strain-to-failure percent, and Young’s modulus were observed for 50-mm-length fibers. Detailed analysis of the longitudinal section of the fiber from atomic force microscopy and scanning electron microscopy study revealed that the fiber had a rough surface, which improves the bonding behavior when reinforced. The aforementioned properties showed that L. camara L. fibers are an excellent, greener alternative reinforcement for composite materials, allowing for the cleaner, more sustainable components.

Microstructural and micromechanical evolution features of asphalt with aging: An atomic force microscopy study

This study explores the aging effects on matrix asphalt (MA) and styrene-butadiene-styrene modified asphalt (SBSMA) using atomic force microscopy (AFM). Aging was simulated with the rolling thin-film oven test (RTFOT) and the pressure aging vessel (PAV) test. Key changes in microtopography, surface roughness, adhesive forces, Young's modulus, and energy dissipation were analyzed. The findings reveal significant microstructural changes with aging, including an increase in the size and a decrease in the number of beelike structures, increased surface roughness, and Young's modulus, which indicate material hardening. The analysis shows a reduction in adhesive force and energy dissipation, suggesting increased brittleness and viscosity. Notably, SBSMA exhibits better aging resistance than MA, as demonstrated by its lower roughness, stronger adhesive forces, and less reduction in energy dissipation, highlighting the effectiveness of the SBS modifier in mitigating aging impacts. These results underscore the critical role of material composition in the aging behavior of asphalt binders.

Adhesion promotion and corrosion resistance of mixed phosphonic acid monolayers on AA 2024

Mixed monolayers were used to prepare surfaces of AA 2024 with precisely controlled corrosion protective and adhesive properties. In this study, the corrosion inhibition and adhesion promotion as a function of the composition of mixed phosphonic acid monolayers on AA 2024 was investigated. Mixed monolayers were formed by competitive adsorption of n-dodecylphosphonic acid (DPA) and 12-aminododecylphosphonic acid (ADPA) from ethanolic solution. Their compositions were determined by X-ray photoelectron spectroscopy. Atomic force microscopy studies and polarization modulation infrared reflection–absorption spectroscopy as well as contact angle studies proved the formation of monolayers with varying surface chemistry. The wet-adhesion strength was tested by 90° peel tests after application of an epoxy-amine adhesive. Linear sweep voltammetry was performed to evaluate the corrosion inhibition of the monolayers, and the corrosion resistance of the metal/adhesive composite was investigated by means of its corrosive delamination behavior. The electrochemical measurements demonstrated that reducing the surface concentration of ADPA improved the corrosion inhibition of the monolayer. However, the corrosive delamination experiments revealed that the improved corrosion inhibition by the self-organized DPA is of minor importance for the corrosion behavior of the metal/adhesive composite, as the adhesive properties dominate.

Evidence of Correlation between Membrane Phase Transition and Clonogenicity in Dehydrating Acinetobacter baumannii: A Combined Micro-Raman and AFM Study.

The Gram-negative bacterium Acinetobacter baumannii is one of the most resilient multidrug-resistant pathogens in hospitals. Among Gram-negative bacteria, it is particularly resistant to dehydration (anhydrobiosis), and this feature allows A. baumannii to persist in hospital environments for long periods, subjected to unfavorable conditions. We leverage the combination of μ-Raman spectroscopy and atomic force microscopy (AFM) to investigate the anhydrobiotic mechanisms in A. baumannii cells by monitoring the membrane (both inner and outer membranes) properties of four A. baumannii strains during a 16-week dehydration period and in response to temperature excursions. We noted that the membranes of A. baumannii remained intact during the dehydration period despite undergoing a liquid-crystal-to-gel-phase transition, accompanied by changes in the mechanical properties of the membrane. This was evident from the AFM images, which showed the morphology of the bacterial cells alongside modifications of their superficial mechanical properties, and from the alteration in the intensity ratio of μ-Raman features linked to the CH3 and CH2 symmetric stretching modes. Furthermore, employing a universal power law revealed a significant correlation between this ratio and bacterial fitness across all tested strains. Additionally, we subjected dry A. baumannii to a temperature-dependent experiment, the results of which supported the correlation between the Raman ratio and culturability, demonstrating that the phase transition becomes irreversible when A. baumannii cells undergo different temperature cycles. Besides the relevance to the present study, we argue that μ-Raman can be used as a powerful nondestructive tool to assess the health status of bacterial cells based on membrane properties with a relatively high throughput.

Chitosan-Surfactant Composite Nanocoatings on Glass and Zinc Surfaces Prepared from Aqueous Solutions.

Hydrophobic coatings from chitosan-surfactant composites (ca. 400 nm thick by UV-Vis spectroscopy) for possible corrosion protection were developed on glass and zinc substrates. The surfactants (sodium dodecyl sulfate, SDS or sodium dodecylbenzenesulfonate, and SDBS) were added to the chitosan by two methods: mixing the surfactants with the aqueous chitosan solutions before film deposition or impregnating the deposited chitosan films with surfactants from their aqueous solutions. For the mixed coatings, it was found that the lower surface tension of solutions (40-45 mN/m) corresponded to more hydrophobic (80-90°) coatings in every case. The hydrophobicity of the impregnated coatings was especially significant (88° for SDS and 100° for SDBS). Atomic force microscopy studies revealed a slight increase in roughness (max 1.005) for the most hydrophobic coatings. The accumulation of surfactants in the layer was only significant (0.8-1.0 sulfur atomic %) in the impregnated samples according to X-ray photoelectron spectroscopy. Polarization and electron impedance spectroscopy tests confirmed better barrier properties for these samples (40-50% pseudo-porosity instead of 94%). The degree of swelling in a water vapor atmosphere was significantly lower in the case of the impregnated coatings (ca. 25%) than that of the native ones (ca. 75%), measured by spectroscopic ellipsometry. Accordingly, good barrier layer properties require advantageous bulk properties in addition to surface hydrophobicity.