Mica Surface Research Articles

Visualizing ribonuclease digestion of RNA-like polymers produced by hot wet-dry cycles

Polymerization of nucleotides under prebiotic conditions simulating the early Earth has been extensively studied. Several independent methods have been used to verify that RNA-like polymers can be produced by hot wet-dry cycling of nucleotides. However, it has not been shown that these RNA-like polymers are similar to biological RNA with 3’-5’ phosphodiester bonds. In the results described here, RNA-like polymers were generated from 5’-monophosphate nucleosides AMP and UMP. To confirm that the polymers resemble biological RNA, ribonuclease A should catalyze hydrolysis of the 3’-5’ phosphodiester bonds between pyrimidine nucleotides to each other or to purine nucleotides, but not purine-purine nucleotide bonds. Here we show AFM images of specific polymers produced by hot wet-dry cycling of AMP, UMP and AMP/UMP (1:1) solutions on mica surfaces, before and after exposure to ribonuclease A. AMP polymers were unaffected by ribonuclease A but UMP polymers disappeared. This indicates that a major fraction of the bonds in the UMP polymers is indeed 3’-5’ phosphodiester bonds. Some of the polymers generated from the AMP/UMP mixture also showed clear signs of cleavage. Because ribonuclease A recognizes the ester bonds in the polymers, we show for the first time that these prebiotically produced polymers are in fact similar to biological RNA but are likely to be linked by a mixture of 3’-5’ and 2’-5’ phosphodiester bonds.

Self-Competitive Growth of CsPbBr3 Planar Nanowire Array.

Semiconductor planar nanowire arrays (PNAs) are essential for achieving large-scale device integration. Direct heteroepitaxy of PNAs on a flat substrate is constrained by the mismatch in crystalline symmetry and lattice parameters between the substrate and epitaxial nanowires. This study presents a novel approach termed "self-competitive growth" for heteroepitaxy of CsPbBr3 PNAs on mica. The key to inducing the self-competitive growth of CsPbBr3 PNAs on mica involves restricting the nucleation of CsPbBr3 nanowires in a high-adsorption region, which is accomplished by overlaying graphite sheets on the mica surface. Theoretical calculations and experimental results demonstrate that CsPbBr3 nanowires oriented perpendicular to the boundary of the high-adsorption area exhibit greater competitiveness in intercepting the growth of nanowires in the other two directions, resulting in PNAs with a consistent orientation. Moreover, these PNAs exhibit low-threshold and stable amplified spontaneous emission under one-, two-, and three-photon excitation, indicating their potential for an integrated laser array.

VO2 nano-rod coated mica composite pearlescent pigment for temperature control packaging

A temperature control mica/VO2 functional pearlescent pigment was designed for the packaging industry. Firstly, a layer of VO2 nanorod film was coated on the surface of flake mica powder by hydrothermal method. Then, the surface of pure mica was modified by silane coupling agent KH-570 and sandwiched between inorganic powders to strengthen the combination. Secondly, the mica/VO2 composite pearlescent powder with gray-green pearlescent effect were successfully obtained by thermal annealing. The crystal structure of the VO2 coating and the chemical valence state of vanadium were verified by X-ray diffraction and X-ray photoelectron spectroscopy. Finally, powders were mixed with polyurethane resin to obtain a functional film. The infrared transmittance of film at 28 °C and 70 °C showed that the composite film with mica content of 3 g had greater temperature control properties, and the difference between high and low temperature transmittance was about 16%. Most importantly, the shiny decorative effect of pearlescent pigment can be still be maintained after being endowed with temperature control property. This work proposes the preparation of functional mica/VO2 composite with pearlescent effect and temperature control property.

Self‐assembly of supramolecular monomers into 2D twinned crystals on mica surface

AbstractDespite the widespread use of microscopy techniques to characterize supramolecular polymers, the role of surfaces in the formation of these structures is unclear. Here we describe the epitaxial growth of intriguing 2D crystals of alkyl benzene‐1,3,5‐triscarboxamides formed by competitive attractive interactions with the mica surface. In contrast to the fibrous structure observed in apolar diluted solution, five‐fold twinned crystals or ribbon‐like structures are obtained on the mica surface. Moreover, these structures are still dynamic on the surface, being able to reorganize during the atomic force microscopy measurements. This work demonstrates that surface‐monomer interactions can be exploited to modulate the structure of 1D supramolecular polymers into 2D crystals.

Influence of Peptoid Sequence on the Mechanisms and Kinetics of 2D Assembly.

Two-dimensional (2D) materials have attracted intense interest due to their potential for applications in fields ranging from chemical sensing to catalysis, energy storage, and biomedicine. Recently, peptoids, a class of biomimetic sequence-defined polymers, have been found to self-assemble into 2D crystalline sheets that exhibit unusual properties, such as high chemical stability and the ability to self-repair. The structure of a peptoid is close to that of a peptide except that the side chains are appended to the amide nitrogen rather than the α carbon. In this study, we investigated the effect of peptoid sequence on the mechanism and kinetics of 2D assembly on mica surfaces using in situ AFM and time-resolved X-ray scattering. We explored three distinct peptoid sequences that are amphiphilic in nature with hydrophobic and hydrophilic blocks and are known to self-assemble into 2D sheets. The results show that their assembly on mica starts with deposition of aggregates that spread to establish 2D islands, which then grow by attachment of peptoids, either monomers or unresolvable small oligomers, following well-known laws of crystal step advancement. Extraction of the solubility and kinetic coefficient from the dependence of the growth rate on peptoid concentration reveals striking differences between the sequences. The sequence with the slowest growth rate in bulk and with the highest solubility shows almost no detachment; i.e., once a growth unit attaches to the island edge, there is almost no probability of detaching. Furthermore, a peptoid sequence with a hydrophobic tail conjugated to the final carboxyl residue in the hydrophilic block has enhanced hydrophobic interactions and exhibits rapid assembly both in the bulk and on mica. These assembly outcomes suggest that, while the π-π interactions between adjacent hydrophobic blocks play a major role in peptoid assembly, sequence details, particularly the location of charged groups, as well as interaction with the underlying substrate can significantly alter the thermodynamic stability and assembly kinetics.

Interaction of surface cations of cleaved mica with water in vapor and liquid forms.

Natural minerals contain ions that become hydrated when they come into contact with water in vapor and liquid forms. Muscovite mica - a common phyllosilicate with perfect cleavage planes - is an ideal system to investigate the details of ion hydration. The cleaved mica surface is decorated by an array of K+ ions that can be easily exchanged with other ions or protons when immersed in an aqueous solution. Despite the vast interest in the atomic-scale hydration processes of these K+ ions, experimental data under controlled conditions have remained elusive. Here, atomically resolved non-contact atomic force microscopy (nc-AFM) is combined with X-ray photoelectron spectroscopy (XPS) to investigate the cation hydration upon dosing water vapor at 100 K in ultra-high vacuum (UHV). The cleaved surface is further exposed to ultra-clean liquid water at room temperature, which promotes ion mobility and partial ion-to-proton substitution. The results offer the first direct experimental views of the interaction of water with muscovite mica under UHV. The findings are in line with previous theoretical predictions.

Alkali silica reaction in concrete - Revealing the expansion mechanism by surface force measurements

Alkali-silica reaction (ASR) is a major cause for concrete deterioration worldwide. However, the mechanism leading to cracking has not been identified yet. In this study, the extended Surface Force Apparatus (eSFA) has been used to determine the surface forces of alkali-silica solutions between two atomically smooth mica surfaces. The setup imitates the situation present in reactive concrete aggregates with negatively charged silicate surfaces and negatively charged polynuclear silica in solution. The distance of strong electrostatic repulsion increases with increasing concentration of dissolved silica, leading to the buildup of pressure up to 6 MPa. When the precipitation of ASR products in confined conditions is triggered by the addition of CaCl2 to the alkali-silica solution, the resulting solidification pressure forces the mica platelets apart and reaches 6–13 MPa. The eSFA experiments shows that solidification pressure is the mechanism leading to aggregate cracking and expansion of ASR-affected concrete.

Iberdomide Enhances Dara Mediated Cytotoxicity through Upregulation of CDC Activity and Elevated NK Cell Mediated ADCC

Background: Multiple Myeloma (MM) is an incurable hematological malignancy with current treatments comprising combination regimens, typically featuring immunomodulatory agents (IMiDs) due to their potent anti-tumor activity and immunomodulatory effects. Clinical studies utilizing the combination of IMiD agents and daratumumab (DARA), an anti-CD38 monoclonal antibody, have shown improved patient outcomes for MM. However, patients ultimately relapse demonstrating the need for novel therapies. Iberdomide (IBER) is a novel cereblon E3 ligase modulator. It promotes faster and deeper degradation of the substrate targets compared to IMiDs, resulting in enhanced anti-proliferative, pro-apoptotic and immune stimulatory activity. In early clinical studies, IBER has been shown to overcome resistance to IMiDs and in the ongoing Phase 3 EXCALIBER study (NCT04975997) is being explored for treatment of newly diagnosed (ND) and relapsed/refractory (RR) MM in combination with DARA and dexamethasone. Here, we investigate the potential mechanisms of synergy between IBER and DARA in preclinical models. Methods: Complement dependent cytotoxicity (CDC) of DARA was assessed with 15% human serum for human complement components and assays were performed by titrating either single agent or combinations in a tritiated thymidine assay. Antibody dependent cellular cytotoxicity (ADCC) was performed by co-culturing MM cells with varying expression levels of CD38 and effector cells and assessing target cell viability with annexin-v/topro-3 flow. A humanized PBMC adoptive transfer mouse model, utilizing human PBMC engraftment 14 days prior to implantation, was used to assess in vivo activity of IBER, DARA and IBER + DARA. Results: In CDC assays, we observed variable sensitivity of MM cells to complement-specific CDC in the presence of DARA (0.1-1 µg/ml), regardless of cell surface CD38 expression. Notably, IBER treatment resulted in upregulation of CD38 surface expression in 60% of MM cell lines tested. LP1 and MOLP8 displayed susceptibility to DARA-mediated CDC. DARA showed a dose-dependent increase in CDC activity in both cell lines. Notably, IBER+DARA also showed ~35% more synergistic CDC activity in both cell lines, than the single agents. In ADCC assays, we observed pretreatment of PBMC with IBER (vs. DMSO) significantly increased DARA mediated ADCC in H929 and LP-1 cells. To confirm that this effect was directed by NK cells, we cultured NK cells for 24 hr in supernatants from stimulated PBMC in presence of IBER prior to co-culture with MM cells. We noted that IBER-treated PBMC supernatant significantly enhanced the NK ADCC activity of DARA suggesting that IBER enhancement of cytokine secretion from PBMC increases NK cell mediated ADCC. Orthogonally, we pre-treated MM cells with IBER or DMSO prior to co-culture in ADCC assay. Notably, IBER treatment of MM cells, without treating immune cells, also increased DARA-mediated ADCC, indicating that IBER directly increases sensitivity to DARA-directed ADCC. To investigate the MOA of IBER-DARA synergy in ADCC, we analyzed gene expression and cell surface changes of a panel of NK-specific receptor ligands on MM cells following treatment with IBER. We observed IBER-induced upregulation of MICA mRNA levels (~2x) and surface expression (~40%) in MM target cells. We used RNAi to knock down Ikaros, an IBER substrate, which resulted in increased MICA expression (~3x) in MM cells. Furthermore, we observed that RNAi knock down of MICA in MM cells resulted in a significant decrease (60%, p<0.0001) in MM cell killing by NK cells, suggesting IBER-enhanced sensitivity of MM cells to NK-cell killing was in part, due to the upregulation of MICA through degradation of Ikaros. Lastly, we examined the anti-MM effects of IBER in a humanized xenograft model with a lenalidomide resistant cell line. Longitudinal analysis identified persistence of human PBMC engraftment and activation of immune subsets (NK cells and T-cells) that were increased upon IBER treatments, consistent with clinical observations. The combination of IBER/DARA resulted in ~22% tumor growth inhibition (TGI) in comparison to single agents, DARA and IBER and ~37% TGI in comparison to vehicle. Conclusion: Taken together, these data demonstrate that IBER and DARA work synergistically in preclinical models primarily through enhancement of both ADCC and CDC. This combination has the potential to improve outcomes in MM.

Geocolloidal interactions and relaxation dynamics under nanoconfinement: Effects of salinity and particle concentration

HypothesisEnergy-related contaminants are frequently associated with geocolloids that translocate in underground fissures with dimensions comparable with geocolloids. To assess the transport and impact of energy-related contaminants in geological systems, fundamental understandings of interfacial behaviors of nanoparticles under confinement is imperative. We hypothesize that the dynamic properties of geocolloids, as well as their dependence on aqueous medium conditions would deviate from bulk behaviors under nanoconfinement. ExperimentsForce profiles and rheological properties of 50 nm silica nanoparticles in aqueous media confined between mica surfaces as a function of surface separation, particle concentrations, and salinity were measured utilizing the surface forces apparatus. FindingsForce profiles revealed the critical surface separation for nonlinear rheological behaviors coincides with the onset of exponential repulsion between mica surfaces. When salts were absent, the normal forces and viscosity values of colloidal suspensions resembled pure water. In contrast, with salts, the force profiles and corresponding critical length scales were found to be highly sensitive to the particle concentration and the degree of confinement. A Newtonian to shear-thinning transition was captured with increasing degrees of confinement. Our results show that the interplay among confinement, particle, and ionic concentrations can alter the interparticle forces and rheological responses of true nanosized-colloidal suspensions and thus their transport behaviors under nanoconfinement for the first time.

Surface diffusion enhanced ion transport through two-dimensional nanochannels

Fast ion permeation in nanofluidic channels has been intensively investigated in the past few decades because of their potential uses in separation technologies and osmotic energy harvesting. Mechanisms governing ion transport at this ultimately small spatial regime remain to be understood, which can only be achieved in nanochannels that are controllably fabricated. Here, we report the fabrication of two-dimensional nanochannels with their top and bottom walls consisting of atomically flat graphite and mica crystals, respectively. The distinct wall structures and properties enable us to investigate interactions between ions and interior surfaces. We find an enhanced ion transport within the channels that is orders of magnitude faster than that in the bulk solutions. The result is attributed to the highly dense packing of adsorbed cations at mica surfaces, where they diffuse in-plane. Our work provides insights into surface effects on ion transport at the nanoscale.

Mica's homo-positive-charging behavior enabled porous elastomer TENG for energy harvesting in high humidity

Tribo-charges upon contact and separation originate from the properties of contacted materials and are of opposite polarities according to the conventional view. Interestingly, mica, as a representative of a series of inorganic materials, always carries positive tribo-charges when two pieces of mica come into contact. Similar homo-charging phenomena have also been observed in other inorganic particles, such as NaCl, quartz, and CaF2. These phenomena are typically encountered during mineral flotation and sand-dust formation and contain abundant triboelectric energy. However, harvesting this disordered and ubiquitous energy is challenging, and a detailed understanding of this homo-positive-charging behavior at the molecular level remains lacking. In this study, the dynamic nature of the homo-positive-charging behavior was verified, and the underlying mechanism for the enhanced evaporation of OH(H2O)n− on the surface of mica was elucidated. Furthermore, mica’s homo-positive-charging behavior was utilized to prepare a porous elastomer, resulting in an endogenous triboelectric nanogenerator (TENG) and an optimized contact–separation mode TENG. The maximum output power density was 55 mW/m2, and 83% of the original energy generation retained at a high humidity of 84.3%. This study contributes to the understanding of mica’s tribo-charging behavior and provides a generic method to optimize positive tribo-layer, especially in high-humidity environments, which show promise in a wide range of applications.

Adsorbing DNA to Mica by Cations: Influence of Valency and Ion Type.

Ion-mediated attraction between DNA and mica plays a crucial role in biotechnological applications and molecular imaging. Here, we combine molecular dynamics simulations and single-molecule atomic force microscopy experiments to characterize the detachment forces of single-stranded DNA at mica surfaces mediated by the metal cations Li+, Na+, K+, Cs+, Mg2+, and Ca2+. Ion-specific adsorption at the mica/water interface compensates (Li+ and Na+) or overcompensates (K+, Cs+, Mg2+, and Ca2+) the bare negative surface charge of mica. In addition, direct and water-mediated contacts are formed between the ions, the phosphate oxygens of DNA, and mica. The different contact types give rise to low- and high-force pathways and a broad distribution of detachment forces. Weakly hydrated ions, such as Cs+ and water-mediated contacts, lead to low detachment forces and high mobility of the DNA on the surface. Direct ion-DNA or ion-surface contacts lead to significantly higher forces. The comprehensive view gained from our combined approach allows us to highlight the most promising cations for imaging in physiological conditions: K+, which overcompensates the negative mica charge and induces long-ranged attractions. Mg2+ and Ca2+, which form a few specific and long-lived contacts to bind DNA with high affinity.

Influence of nanoscale spatial architecture of seed and root mucilage on its wettability

Mucilage secreted by root-tips may alter hydraulic conditions at the root-soil interface and seed coat mucilage increases water availability for seeds. Both significantly affect the water content dynamics of the rhizosphere. Therefore, we examined the nanostructure of different types of dried mucilage (root or seed mucilage and mucilage from different species) and how it affects their wettability. We hypothesized that with increasing roughness wettability of dried mucilage decreases based on the Cassie−Baxter relation due to entrapped air in holes formed in the mucilage layer during drying. In order to visualize the nanostructure of different mucilage species, we dried root mucilage from aeroponically grown seedlings (maize, cress, flax, wheat, barley) and seed mucilage (cress and flax) as thin layers on flat mica surfaces. Spatial structures of the samples were visualized by atomic force microscopy. Variogram analysis was used to analyze the spatially resolved topography data, and the coverage of mucilage was quantified using GeoDict® software. Moreover, by the pore size distribution, the effect of hole-size dispersity on mucilage's wettability was investigated. Our results demonstrate that mucilage of different species have different nanostructures. In contrast to expectations, the wettability of dried mucilage does not follow the Cassie−Baxter relation and does not decrease with increasing roughness. We conclude that wettability of surfaces decreases with increasing mucilage coverage. The lower the coverage the more hydrophilic area of the underlying mineral surface contributes to the overall wettability.

Low-cost and highly thermally conductive silver modified mica-paraffin multifunctional composite phase change materials for photo-thermal conversion and electrical insulation

To improve the utilization efficiency of renewable energy and adaptability of composite materials, a new mineral-based composite phase change material (Ag-Mica/CNF/PW) was designed and prepared by chemically modifying natural mica, attaching silver nanoparticles to the mica surface as functionalized support material, and using paraffin wax as the phase change functional medium. As expected, the thermal conductivity of the composite phase change material (CPCMs) increased significantly to 0.9 W/m k, which was 330.1% higher relative to pure paraffin. With the addition of silver-modified mica, the volume resistivity of CPCMs reached 11.9 × 1012 Ω cm. The relative enthalpy efficiency achieved 104.8%, and the photothermal conversion efficiency reached 91.3%, proving that the silver-modified mica-based CPCM was successful and feasible. The heat resistance index of CPCMs was 137.2 °C, and the enthalpy loss rate after 50 cycles was only 0.7 %, indicating that CPCMs have excellent thermal stability. The designed CPCMs are a promising candidate for developing thermal storage and building thermal management, electrical insulation and solar energy conversion.

Adaptive Adhesions of Barnacle-Inspired Adhesive Peptides.

The strategy of robust adhesion employed by barnacles renders them fascinating biomimetic candidates for developing novel wet adhesives. Particularly, barnacle cement protein 19k (cp19k) has been speculated to be the key adhesive protein establishing the priming layer in the initial barnacle cement construction. In this work, we systematically studied the sequence design rationale of cp19k by designing adhesive peptides inspired by the low-complexity STGA-rich and the charged segments of cp19k. Combining structure analysis and the adhesion performance test, we found that cp19k-inspired adhesive peptides possess excellent disparate adhesion strategies for both hydrophilic mica and hydrophobic self-assembled monolayer surfaces. Specifically, the low-complexity STGA-rich segment offers great structure flexibility for surface adhesion, while the hydrophobic and charged residues can contribute to the adhesion of the peptides on hydrophobic and charged surfaces. The adaptive adhesion strategy identified in this work broadens our understanding of barnacle adhesion mechanisms and offers valuable insights for designing advanced wet adhesives with exceptional performance on various types of surfaces.

Influence of Temperature-Guided SAM Growth on Wetting and Its Mass Transfer Models.

The formation and growth of self-assembled monolayers (SAMs) composed of amphiphiles have garnered significant attention due to their diverse technical applications. This article reports the findings of molecular dynamics simulations aimed at elucidating the intricate relationship between the wetting behavior of amphiphiles, specifically n-alkanols, and the growth of their SAMs on a mica surface under varying temperature conditions. The investigation quantifies the structural characteristics of the formed SAMs, including density profiles, in-plane radial distribution functions, order parameters, and end-to-end length distributions of n-alkanol molecules within the SAM. Thermodynamic properties, such as the second virial coefficient and excess entropy, are examined in relation to temperature and time. The growth of the SAM is assessed by analyzing characteristic time scales at different temperatures and in-plane diffusion of n-alkanol molecules and utilizing classical theories of mass transfer to quantify the growth rate as a function of temperature. These results are then correlated with changes in the contact angle and spreading coefficient of n-alkanol droplets on the mica surface over time, providing insights into the impact of SAM growth on the wetting behavior and the mass transfer model of such systems.

The regulation of surface nanobubble generation via solvent exchange on different substrates

Surface nanobubbles (SNBs) play an essential role in fluid transport, interfacial reactions, electrochemistry, material fabrication, surface cleaning, etc. Controllable preparation of SNBs is very crucial for their applications, such as controlling material preparation and increasing the efficiency of surface cleaning. Ethanol-water exchange, as a typical example of solvent exchange, is one of the most widely used methods to produce SNBs. By controlling the conditions, it is possible to manipulate the size and number density of nanobubbles. In this work, we systematically investigated the formation of SNBs on hydrophobic and hydrophilic surfaces by ethanol-water exchange at different rates using atomic force microscopy. Results indicate that the exchange rate has a significant effect on the size and number density of SNBs. On both hydrophobic surface of highly oriented pyrolytic graphite (HOPG) and hydrophilic surface of mica, formed nanobubbles exhibit smaller sizes and higher number density with increased exchange rates. But at the same solvent exchange rate, SNBs generated on HOPG surface were in greater number and width than on mica, while their heights change much less. To understand the effect of exchange rate on nanobubble production, we proposed a mechanism of non-uniform nucleation and diffusion-driven growth. A simulation of the gas concentration near SNBs was performed, and the results show good agreement between numerical calculations and experimental data. We believe that our results will contribute to the understanding of nanobubble generation and stabilization processes. It also provides a new perspective on the factors that affect the generation of SNBs, which allows the production and application of nanobubbles to be controlled in a reliable manner.

Electrocoagulation in a packed aluminium scraps anode reactor for mineral processing wastewater treatment

Efficient treatment and purification of mineral processing wastewater (MPW) have not been sufficiently investigated in the past though they are of great importance for sustainable mineral processing. Herein, a unique electrocoagulation (EC) reactor with aluminium scraps as anode material was developed for the treatment of real industrial MPW containing residual flotation reagents (major contributor to chemical oxygen demand, COD) and suspended particles. It was found that the active coagulants produced from the dissolution of aluminium scraps can play a key role in the purification of MPW. Under the conditions of initial pH 9, current 1 A, and processing time 90 min, the removal rate of COD was 74% while the turbidity can be almost completely removed. The mechanism lies in that most of the flotation reagents was adsorbed on the surfaces of suspended mineral particles, namely, montmorillonite, quartz, garnet, chlorite and mica, and then precipitated with the mineral particles. This innovative technology of utilizing wasted aluminium scraps to treat MPW is in line with the green development.

Nanostructures and Thin Films of Poly(Ethylene Glycol)-Based Surfactants and Polystyrene Nanocolloid Particles on Mica: An Atomic Force Microscopy Study

We studied the nanostructures and ultrathin films resulting from the deposition and adsorption of polystyrene nanocolloidal particles and methoxy poly(ethylene glycol) methacrylate surfactants on mica surfaces from mixed suspensions in water. The samples were prepared by droplet evaporation and dip coating and imaged with atomic force microscopy. Topography and phase imaging revealed a significant richness in morphological features of the deposited/adsorbed films. We observed uniform ultrathin films and extended islands of the surfactant oligomers indicating their self-assembly in monolayers and multilayers, while the polystyrene nanocolloids were embedded within the surfactant structures. Droplet evaporation resulted in the migration of particles towards the edges of the droplet leaving an intricate network of imprints within the surfactant film. Dip coating induced the formation of extended nanocolloid clusters with colloidal crystalline structuring.

Size-Dependent Mechanical Property Measurement of 1,2-dioleoyl-SN-3-phosphocholine Liposome Using Atomic Force Microscopy

Most studies have reported on the effects of bending rigidity using giant unilamellar liposomes. However, few studies have been conducted on nanosized liposomes. We studied the properties of DOPC liposomes of various sizes using atomic force microscopy (AFM). Two different topographies (convex and planar) of DOPC liposomes on a mica surface were observed in the tapping mode in the fluid. The topographic change of the liposomes could be attributed to the interaction force between the AFM tip and the liposome. Small DOPC liposomes (below 1 μm) showed a bending modulus (kbend) ranging between 10−18 and 10−20 J. The bending modulus was found to be size-dependent; it decreased as DOPC liposome size increased. In this study, images of unilamellar DOPC liposomes were obtained in the contact mode. The bending moduli of lipid vesicles from 100 to 1300 nm were measured using an AFM force curve. The bending modulus tended to increase as liposome size decreased. From experimental and theoretical perspectives, we showed that the value of the bending modulus is proportional to 1.5 power of the radius of the liposome.