High-resolution Atomic Force Microscopy Images Research Articles

Integration of piezoelectric and electrothermal actuators for high-resolution Atomic Force Microscopy

The development of ultrasensitive silicon-based microcantilevers has significantly improved the imaging resolution of the Atomic Force Microscope (AFM). However, most of these microcantilevers require one or more external actuators and sensors for imaging, thus increasing the footprint and operational complexity of the instrument. Here we propose a novel active microcantilever that does not require any external actuator apart from the sample positioner to perform high-resolution AFM imaging. The proposed microcantilever is equipped with two different on-chip actuators: a piezoelectric actuator for oscillating the probe at a high frequency and an electrothermal actuator for providing large-range Z-motion. An on-chip differential piezoelectric sensor measures probe oscillation during imaging. To demonstrate the proof of concept, the microcantilever was microfabricated and integrated with an in-house developed AFM setup comprising of sample positioner and drive electronics. Finally, 3 different calibration gratings were imaged with a closed-loop bandwidth of 150Hz.

Machine Learning Allows for Distinguishing Precancerous and Cancerous Human Epithelial Cervical Cells Using High-Resolution AFM Imaging of Adhesion Maps.

Previously, the analysis of atomic force microscopy (AFM) images allowed us to distinguish normal from cancerous/precancerous human epithelial cervical cells using only the fractal dimension parameter. High-resolution maps of adhesion between the AFM probe and the cell surface were used in that study. However, the separation of cancerous and precancerous cells was rather poor (the area under the curve (AUC) was only 0.79, whereas the accuracy, sensitivity, and specificity were 74%, 58%, and 84%, respectively). At the same time, the separation between premalignant and malignant cells is the most significant from a clinical point of view. Here, we show that the introduction of machine learning methods for the analysis of adhesion maps allows us to distinguish precancerous and cancerous cervical cells with rather good precision (AUC, accuracy, sensitivity, and specificity are 0.93, 83%, 92%, and 78%, respectively). Substantial improvement in sensitivity is significant because of the unmet need in clinical practice to improve the screening of cervical cancer (a relatively low specificity can be compensated by combining this approach with other currently existing screening methods). The random forest decision tree algorithm was utilized in this study. The analysis was carried out using the data of six precancerous primary cell lines and six cancerous primary cell lines, each derived from different humans. The robustness of the classification was verified using K-fold cross-validation (K = 500). The results are statistically significant at p < 0.0001. Statistical significance was determined using the random shuffle method as a control.

Antioxidant Activities of Photoinduced Phycogenic Silver Nanoparticles and Their Potential Applications.

While various methods exist for synthesizing silver nanoparticles (AgNPs), green synthesis has emerged as a promising approach due to its affordability, sustainability, and suitability for biomedical purposes. However, green synthesis is time-consuming, necessitating the development of efficient and cost-effective techniques to minimize reaction time. Consequently, researchers have turned their attention to photo-driven processes. In this study, we present the photoinduced bioreduction of silver nitrate (AgNO3) to AgNPs using an aqueous extract of Ulva lactuca, an edible green seaweed. The phytochemicals found in the seaweed functioned as both reducing and capping agents, while light served as a catalyst for biosynthesis. We explored the effects of different light intensities and wavelengths, the initial pH of the reaction mixture, and the exposure time on the biosynthesis of AgNPs. Confirmation of AgNP formation was achieved through the observation of a surface plasmon resonance band at 428 nm using an ultraviolet-visible (UV-vis) spectrophotometer. Fourier transform infrared spectroscopy (FTIR) revealed the presence of algae-derived phytochemicals bound to the outer surface of the synthesized AgNPs. Additionally, high-resolution transmission electron microscopy (HRTEM) and atomic force microscopy (AFM) images demonstrated that the NPs possessed a nearly spherical shape, ranging in size from 5 nm to 40 nm. The crystalline nature of the NPs was confirmed by selected area electron diffraction (SAED) and X-ray diffraction (XRD), with Bragg's diffraction pattern revealing peaks at 2θ = 38°, 44°, 64°, and 77°, corresponding to the planes of silver 111, 200, 220, and 311 in the face-centered cubic crystal lattice of metallic silver. Energy-dispersive X-ray spectroscopy (EDX) results exhibited a prominent peak at 3 keV, indicating an Ag elemental configuration. The highly negative zeta potential values provided further confirmation of the stability of AgNPs. Moreover, the reduction kinetics observed via UV-vis spectrophotometry demonstrated superior photocatalytic activity in the degradation of hazardous pollutant dyes, such as rhodamine B, methylene orange, Congo red, acridine orange, and Coomassie brilliant blue G-250. Consequently, our biosynthesized AgNPs hold great potential for various biomedical redox reaction applications.

The cyto-linker and scaffolding protein "plectin" mis-localization leads to softening of cancer cells.

Discovering tools to prevent cancer progression requires understanding the fundamental differences between normal and cancer cells. More than a decade ago, atomic force microscopy (AFM) revealed cancer cells' softer body compared to their healthy counterparts. Here, we investigated the mechanism underlying the softening of cancerous cells in comparison with their healthy counterparts based on AFM high resolution stiffness tomography and 3D confocal microscopy. We showed microtubules (MTs) network in invasive ductal carcinoma cell cytoskeleton is basally located and segmented for around 400 nm from the cell periphery. Additionally, the cytoskeleton scaffolding protein plectin exhibits a mis-localization from the cytoplasm to the surface of cells in the carcinoma which justifies the dissociation of the MT network from the cell's cortex. Furthermore, the assessment of MTs' persistence length using a worm-like-chain (WLC) model in high resolution AFM images showed lower persistence length of the single MTs in ductal carcinoma compared to that in the normal state. Overall, these tuned mechanics support the invasive cells to ascertain more flexibility under compressive forces in small deformations. These data provide new insights into the structural origins of cancer aids in progression.

Nanoscale probing of local dielectric changes at the interface between solids and aqueous saline solutions.

The mobility of dissolved ions and charged molecules at interfaces underpins countless processes in science and technology. Experimentally, this is typically measured from the averaged response of the charges to an electrical potential. High-resolution Atomic Force Microscopy (AFM) can image single adsorbed ions and molecules at solid-liquid interfaces, but probing the associated dynamics remains highly challenging. One possible strategy is to investigate the response of the species of interest to a highly localized AC electric field in an approach analogous to dielectric spectroscopy. The dielectric force experienced by the AFM tip apex is modulated by the dielectric properties of the sample probed, itself sensitive to the mobilities of solvated charges and dipoles. Previous work successfully used this approach to quantify the dielectric constant of thin samples, but with limited spatial resolution. Here we propose a strategy to simultaneously map the nanoscale topography and local dielectric variations across a range of interfaces by conducting high-resolution AFM imaging concomitantly with electrical AC measurements in a multifrequency approach. The strategy is tested over a 500 MHz bandwidth in pure liquids with different dielectric constants and in saline aqueous solutions. In liquids with higher dielectric constants, the system behaves as inductive-resistive-capacitive but the adjunction of ions removes the inductive resonances and precludes measurements at higher frequencies. High-resolution imaging is demonstrated over single graphene oxide (GrO) flakes with simultaneous but decoupled dielectric measurements. The dielectric constant is consistent and reproducible across liquids, except at higher salt concentrations where frequency-dependent effects occur. The results suggest the strategy is suitable for nanometre-level mapping of the dielectric properties of solid-liquid interfaces, but more work is needed to fully understand the different physical effects underpinning the measurements.

Nanoscale chemomechanical variations of montmorillonite induced by the specificity of counterions—An in situ XRD and AFM study

The variable structural characteristics of montmorillonite (Mnt) in salt solutions depend not only on the quantity and distribution of the Mnt layer charge, but also on the specificity of counterions, including their radius, valence, concentration, and hydratability. In order to determine the nanoscale chemomechanical processes in a clay mineral–water–salt system, in situ X-ray diffraction (XRD) and atomic force microscopy (AFM) methods were used to investigate the structural variations of Mnt caused by different counterion species (e.g., Li+, Na+, K+, Rb+, Cs+, Mg2+, Ca2+, and Sr2+) at different concentrations (0.2–3.0 M). With an increasing concentration of counterions, separation of water molecules from the interlayer space of more weakly hydrated cations (Cs+, Rb+, and K+) is faster than for the more strongly hydrated cations (Li+, Na+, Mg2+, Ca2+, and Sr2+), water molecules are lost more slowly from the hydration shell, which remains stable even at high counterion concentrations. The sequential ion exchange in a monolayer Mnt observed by in situ AFM is consistent with the d(001) results from the real-time XRD analysis. Moreover, various defects on Mnt surfaces were visible in the high-resolution AFM images, which restrict the spatial arrangement of adsorbed cations. The water molecule partitioning between the interlayers in Mnt is controlled by the specificity of the counterions, and the cations can spontaneously form ordered structures on the surface of Mnt. These nonclassical interfacial phenomena occurred in the electric double layer (EDL) is controlled by the hydration of counterions, the surface structure and the charge distribution of Mnt.

Antibiotic polymyxin arranges lipopolysaccharide into crystalline structures to solidify the bacterial membrane

Polymyxins are last-resort antibiotics with potent activity against multi-drug resistant pathogens. They interact with lipopolysaccharide (LPS) in bacterial membranes, but mechanistic details at the molecular level remain unclear. Here, we characterize the interaction of polymyxins with native, LPS-containing outer membrane patches of Escherichia coli by high-resolution atomic force microscopy imaging, along with structural and biochemical assays. We find that polymyxins arrange LPS into hexagonal assemblies to form crystalline structures. Formation of the crystalline structures is correlated with the antibiotic activity, and absent in polymyxin-resistant strains. Crystal lattice parameters alter with variations of the LPS and polymyxin molecules. Quantitative measurements show that the crystalline structures decrease membrane thickness and increase membrane area as well as stiffness. Together, these findings suggest the formation of rigid LPS–polymyxin crystals and subsequent membrane disruption as the mechanism of polymyxin action and provide a benchmark for optimization and de novo design of LPS-targeting antimicrobials.

High-Resolution Atomic Force Microscopy Imaging of RNA Molecules in Solution.

Atomic force microscopy (AFM) is an important and versatile technique to investigate the structures and dynamics of biomolecules under physiologically relevant conditions at the single-molecule level. Recent progresses in high-resolution AFM imaging of nucleic acids have expanded this technique from simple characterization of double-stranded DNA or RNA to detailed analyses of the structure and dynamics of large functional RNAs with complex folds. Several technical developments, such as sharper probes and more stable instruments with novel imaging modes, AFM is capable of directly visualizing RNA conformational heterogeneity in solution in real time. Here, we introduce a comprehensive method for recording high-resolution images of RNA molecules, including sample preparation, instrument setup, data acquisition, and image processing.

3D Generation of Multipurpose Atomic Force Microscopy Tips

In this work, 3D polymeric atomic force microscopy (AFM) tips, referred to as 3DTIPs, are manufactured with great flexibility in design and function using two‐photon polymerization. With the technology holding a great potential in developing next‐generation AFM tips, 3DTIPs prove effective in obtaining high‐resolution and high‐speed AFM images in air and liquid environments, using common AFM modes. In particular, it is shown that the 3DTIPs provide high‐resolution imaging due to their extremely low Hamaker constant, high speed scanning rates due to their low quality factor, and high durability due to their soft nature and minimal isotropic tip wear; the three important features for advancing AFM studies. It is also shown that refining the tip end of the 3DTIPs by focused ion beam etching and by carbon nanotube inclusion substantially extends their functionality in high‐resolution AFM imaging, reaching angstrom scales. Altogether, the multifunctional capabilities of 3DTIPs can bring next‐generation AFM tips to routine and advanced AFM applications, and expand the fields of high speed AFM imaging and biological force measurements.

On-Surface Synthesis of Unsaturated Hydrocarbon Chains through C-S Activation.

We use an on‐surface synthesis approach to drive the homocoupling reaction of a simple dithiophenyl‐functionalized precursor on Cu(111). The C−S activation reaction is initiated at low annealing temperature and yields unsaturated hydrocarbon chains interconnected in a fully conjugated reticulated network. High‐resolution atomic force microscopy imaging reveals the opening of the thiophenyl rings and the presence of trans‐ and cis‐oligoacetylene chains as well as pentalene units. The chemical transformations were studied by C 1s and S 2p core level photoemission spectroscopy and supported by theoretical calculations. At higher annealing temperature, additional cyclization reactions take place, leading to the formation of small graphene flakes.

Probing the Structural Details of Chitin Nanocrystal–Water Interfaces by Three‐Dimensional Atomic Force Microscopy

Chitin is one of the most abundant and renewable natural biopolymers. It exists in the form of crystalline microfibrils and is the basic structural building block of many biological materials. Its surface crystalline structure is yet to be reported at the molecular level. Herein, atomic force microscopy (AFM) in combination with molecular dynamics simulations reveals the molecular-scale structural details of the chitin nanocrystal (chitin NC)-water interface. High-resolution AFM images reveal the molecular details of chitin chain arrangements at the surfaces of individual chitin NCs, showing highly ordered, stable crystalline structures almost free of structural defects or disorder. 3D-AFM measurements with submolecular spatial resolution demonstrate that chitin NC surfaces interact strongly with interfacial water molecules creating stable, well-ordered hydration layers. Inhomogeneous encapsulation of the underlying chitin substrate by these hydration layers reflects the chitin NCs' multifaceted surface character with different chain arrangements and molecular packing. These findings provide important insights into chitin NC structures at the molecular level, which is critical for developing the properties of chitin-based nanomaterials. Furthermore, these results will contribute to a better understanding of the chemical and enzymatic hydrolysis of chitin and other native polysaccharides, which is also essential for the enzymatic conversion of biomass.

The articular cartilage surface is impaired by a loss of thick collagen fibers and formation of type I collagen in early osteoarthritis

Osteoarthritis (OA) is a joint disease affecting millions of patients worldwide. During OA onset and progression, the articular cartilage is destroyed, but the underlying complex mechanisms remain unclear. Here, we uncover changes in the thickness of collagen fibers and their composition at the onset of OA. For articular cartilage explants from knee joints of OA patients, we find that type I collagen-rich fibrocartilage-like tissue was formed in macroscopically intact cartilage, distant from OA lesions. Importantly, the number of thick fibers (>100 nm) has decreased early in the disease, followed by complete absence of thick fibers in advanced OA. We have obtained these results by a combination of high-resolution atomic force microscopy imaging under near-native conditions, immunofluorescence, scanning electron microscopy and a fluorescence-based classification of the superficial chondrocyte spatial organization. Taken together, our data suggests that the loss of tissue functionality in early OA cartilage is caused by a reduction of thick type II collagen fibers, likely due to the formation of type I collagen-rich fibrocartilage, followed by the development of focal defects in later OA stages. We anticipate that such an integrative characterization will be very beneficial for an in-depth understanding of other native biological tissues and the development of sustainable biomaterials. Statement of significanceIn early osteoarthritis (OA) the cartilage appears macroscopically intact. However, this study demonstrates that the collagen network already changes in early OA by collagen fiber thinning and the formation of fibrocartilage-like tissue. Both nanoscopic deficiencies already occur in macroscopically intact regions of the human knee joint and are likely connected to processes that result in a weakened extracellular matrix. This study enhances the understanding of earliest progressive cartilage degeneration in the absence of external damage. The results suggest a determination of the mean collagen fiber thickness as a new target for the detection of early OA and a regulation of type I collagen synthesis as a new path for OA treatment.

Crystal structure and self-assembly on graphite of a pyrazolo[1,5-c]pyrimidine derivative.

The crystal structure of the heterocyclic compound 2-(4-methoxyphenyl)-7-phenylpyrazolo[1,5-c]pyrimidine, C19H15N3O, has been determined and its self-assembly on the surface of graphite has been examined using atomic force microscopy (AFM). The title compound crystallized in the monoclinic space group P21/c, with two independent molecules in the asymmetric unit. The packing of the L-shaped molecules in the crystal is governed by arene interactions, in the absence of any conventional hydrogen-bonding interactions. The packing arrangement reveals four types of dimeric motifs stabilized by π-π and C-H...π interactions. At low coverage, molecules assemble into long needle-like islands on the graphite surface. High-resolution AFM images reveal that the molecules interact through weak noncovalent interactions between the aromatic H atoms and the methoxy O atoms.

Revealing DNA Structure at Liquid/Solid Interfaces by AFM-Based High-Resolution Imaging and Molecular Spectroscopy.

DNA covers the genetic information in all living organisms. Numerous intrinsic and extrinsic factors may influence the local structure of the DNA molecule or compromise its integrity. Detailed understanding of structural modifications of DNA resulting from interactions with other molecules and surrounding environment is of central importance for the future development of medicine and pharmacology. In this paper, we review the recent achievements in research on DNA structure at nanoscale. In particular, we focused on the molecular structure of DNA revealed by high-resolution AFM (Atomic Force Microscopy) imaging at liquid/solid interfaces. Such detailed structural studies were driven by the technical developments made in SPM (Scanning Probe Microscopy) techniques. Therefore, we describe here the working principles of AFM modes allowing high-resolution visualization of DNA structure under native (liquid) environment. While AFM provides well-resolved structure of molecules at nanoscale, it does not reveal the chemical structure and composition of studied samples. The simultaneous information combining the structural and chemical details of studied analyte allows achieve a comprehensive picture of investigated phenomenon. Therefore, we also summarize recent molecular spectroscopy studies, including Tip-Enhanced Raman Spectroscopy (TERS), on the DNA structure and its structural rearrangements.

Abnormal diffusion profile of adatoms on extremely wide terraces of the Si(111) surface

The authors experimentally studied the distribution of the adatom concentration on extremely wide terraces of the Si(111) surface whose dimensions are comparable with the diffusion length of adatoms. The extremely wide terraces were created during in situ experiments carried out by ultrahigh vacuum reflection electron microscopy by high-temperature annealing of Si(111) samples (more than 1000 °C) followed by rapid cooling to 750 °C to form 7 × 7 superstructure domains. A detailed analysis of the surface morphology of the terraces was carried out by ex situ atomic force microscopy under ambient conditions. Based on high-resolution (1.2 nm/pixel) atomic force microscopy images, panoramic topographic images of the terraces were formed. Digital processing of the panoramic images visualized the distribution of the adatom concentration n. For a terrace cooled from 1070 °C, central terrace regions show minimum n values around 0.13 BL (1 bilayer (BL) = 1.56×1015 cm−2); close to the monatomic step bordering the terrace, n increases to about 0.14 BL. The authors determined that this radial distribution n(r) at 1070 °C corresponds to the adatom diffusion coefficient D = 59 ± 12 μm2/s. It was found that, for a terrace cooled from 1090 °C, the approach assuming the same adatom diffusion length over the entire terrace does not describe the experimental n(r) distribution. For its analysis, the authors used the solution of the stationary diffusion equation under the assumption that D is not constant. Based on a numerical solution, the dependence of D on the experimentally measured n values was obtained. Under the assumption that adatom lifetime does not depend on n at 1090 °C, the adatom diffusion coefficient was found to decrease from 140 μm2/s at n = 0.093 BL (in the central terrace regions) to 5 μm2/s at n = 0.118 BL (near the step). The results of this work experimentally demonstrated that the control over adatom concentration can be used to significantly vary the diffusion properties of the adsorption layer on the crystal surface.

Self-assembly of Eucalyptus gunnii wax tubules and pure ß-diketone on HOPG and glass.

Eucalyptus trees and many plants from the grass family (Poaceae) and the heather family (Ericaceae) have a protective multifunctional wax coating on their surfaces made of branched ß-diketone tubules. ß-diketone tubules have a different size, shape, and chemical composition than the well-described nonacosanol tubules of the superhydrophobic leaves of lotus (Nelumbo nucifera). Until now the formation process of ß-diketone tubules is unknown. In this study, extracted wax of E. gunnii leaves and pure ß-diketone were recrystallized on two different artificial materials and analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM) to study their formation process. Both the wax mixture and pure ß-diketone formed tubules similar to those on E. gunnii leaves. Deviating platelet-shaped and layered structures not found on leaves were also formed, especially on areas with high mass accumulation. High-resolution AFM images of recrystallized ß-diketone tubules are presented for the first time. The data showed that ß-diketone tubules are formed by self-assembly and confirmed that ß-diketone is the shape-determining component for this type of tubules.

Water and oxygen environment induced surface cracks healing in solution processed gallium oxide thin films

Solution based low temperature gallium oxide (Ga2O3) films with high quality is present need for large area deposition, cracks and other parameters resist the use of these films in applications. We have tried to develop good quality crack free films of Ga2O3. Deposition of Ga2O3 thin films by spin coating method and investigation of removal of surface cracks by adding secondary solvent (water) under oxygen environment. The as-synthesized film (without water and oxygen) shows cracks all over the surface. Deionized (DI) water and oxygen atmosphere act as efficient medium that alter surface energy of thin films while undergoing heat treatment. During the heat treatment of the thin films, addition of water forms interparticulate system between the molecules, yielding better evaporation balance and the oxygen environment helps to seize the rate of molecule evaporation which improves the surface uniformity of the thin film. A significant variation in the surface morphology of the films is observed using high-resolution scanning electron microscopy (SEM) and atomic force microscopy (AFM) images. X-ray diffraction (XRD) and Raman spectroscopy are used for the structural confirmation of the thin films. Increase in surface roughness is observed (from 0.28 nm to 0.98 nm) with increase in annealing temperature. Improvement in the crystalline feature results into augmented current density value. The developed crack-free films can be utilized for various electronics and optoelectronics application.

On-Surface Synthesis of One-Dimensional Coordination Polymers with Tailored Magnetic Anisotropy.

One-dimensional (1D) metalloporphyrin polymers can exhibit magnetism, depending on the central metal ion and the surrounding ligand field. The possibility of tailoring the magnetic signal in such nanostructures is highly desirable for potential spintronic devices. We present low-temperature (4.2 K) scanning tunneling microscopy and spectroscopy (LT-STM/STS) in combination with high-resolution atomic force microscopy (AFM) and a density functional theory (DFT) study of a two-step synthetic protocol to grow a robust Fe-porphyrin-based 1D polymer on-surface and to tune its magnetic properties. A thermally assisted Ullmann-like coupling reaction of Fe(III)diphenyl-bromine-porphyrin (2BrFeDPP-Cl) on Au(111) in ultra-high vacuum results in long (up to 50 nm) 1D metal-organic wires with regularly distributed magnetic and (electronically) independent porphyrins units, as confirmed by STM images. Thermally controlled C-H bond activation leads to conformational changes in the porphyrin units, which results in molecular planarization steered by 2D surface confinement, as confirmed by high-resolution AFM images. Spin-flip STS images in combination with DFT self-consistent spin-orbit coupling calculations of porphyrin units with different structural conformations reveal that the magnetic anisotropy of the triplet ground state of the central Fe ion units drops down substantially upon intramolecular rearrangements. These results point out to new opportunities for realizing and studying well-defined 1D organic magnets on surfaces and demonstrate the feasibility of tailoring their magnetic properties.

Interaction of LL-37 human cathelicidin peptide with a model microbial-like lipid membrane

The only representative of cathelicidin peptides in humans is LL-37, a multifunctional antimicrobial peptide (AMP) that is a part of the innate immune response. Details of the LL-37 direct activity against pathogens are not well understood at the molecular level. Here, we present research on the mechanism of interaction between LL-37 and a model multicomponent bilayer lipid membrane (BLM), mimicking microbial cell membrane. Electrochemical impedance spectroscopy (EIS), high-resolution atomic force microscopy (AFM) imaging, and polarization-modulation infrared reflection–absorption spectroscopy (PM-IRRAS) were applied to study the peptide influence on a model microbial-like membrane. We show that LL-37 causes changes in the phospholipid molecules conformation and orientation, leading to membrane disintegration, significantly affecting the membrane electrical parameters, such as capacitance and resistance. High-resolution AFM imaging shows topographical and mechanical effects of such disintegration, while PM-IRRAS data indicates that introduction of LL-37 causes changes in the phospholipid acyl chains from all-trans to gauche conformations. Moreover, the presence of LL-37 significantly alters the value of the phospholipid tilt angle. Altogether, our results suggest a “carpet” membrane dissolution followed by a detergent-like membrane disruption mechanism upon LL-37 activity. This research gives a novel insight into the understanding of LL-37 influence on multicomponent model membranes and a promising contribution to the development of LL-37-derived therapeutic agents against drug-resistant bacteria.

In Situ Reproducible Sharp Tips for Atomic Force Microscopy

Atomically sharp tips are a requirement for scanning-probe microscopy, such as scanning tunneling microscopy (STM) and atomic force microscopy (AFM). Compared with STM, AFM imaging is more sensitive to the sharpness of tip apices because long-range forces act as a background signal on the high-resolution AFM images originating from short-range forces. Here we report the investigation of in situ reproducible sharp tips for AFM. We make an ${\mathrm{Ag}}_{2}\mathrm{S}$ crystal, a mixed ionic and electronic conductor, on a conventional $\mathrm{Si}$ cantilever, and controllably grow and shrink the $\mathrm{Ag}$ nanoprotrusion by changing the polarity of the bias voltage between the tip and the sample. We are able to reduce the contribution of long-range forces by growing a $\mathrm{Ag}$ nanoprotrusion on the ${\mathrm{Ag}}_{2}\mathrm{S}$ tip, and obtain atomic-resolution AFM images. We also confirm that the ${\mathrm{Ag}}_{2}\mathrm{S}$ tip with a $\mathrm{Ag}$ nanoprotrusion, the end of which presumably terminates in $\mathrm{Si}$ atoms, is capable of simultaneous AFM and STM measurements.