Cellular mechanics, a major regulating factor of cellular architecture and biological functions, responds to intrinsic stresses and extrinsic forces exerted by other cells and the extracellular matrix in the microenvironment. Cellular mechanics also acts as a fundamental mediator in complicated immune responses, such as cell migration, immune cell activation, and pathogen clearance. The principle of atomic force microscopy (AFM) and its three running modes are introduced for the mechanical characterization of living cells. The peak force tapping mode provides the most delicate and desirable virtues to collect high-resolution images of morphology and force curves. For a concrete description of AFM capabilities, three AFM applications are discussed. These applications include the dynamic progress of a neutrophil-extracellular-trap release by neutrophils, the immunological functions of macrophages, and the membrane pore formation mediated by perforin, streptolysin O, gasdermin D, or membrane attack complex.
Microscopy, Atomic Force ; Neutrophils

PURPOSE: To investigate the effects of mitomycin C on the scleral collagen surfaces using atomic force microscopy (AFM). METHODS: Two non-contact mode AFM machines were used to observe changes in the morphological characteristics of human scleral surfaces before and after one, three, and five minutes of 0.02% mitomycin C application. Based on AFM topography and deflection images of the collagen fibril, the morphological characteristics of scleral fibrils including the fibril diameter and D-period were measured using the line profile. RESULTS: The sclera collagen fibril treated with 0.02% mitomycin C for one minute did not show any significant increases in mean fibril diameter (155.04 +/- 17.46 nm) or mean D-periodicity (70.02 +/- 3.33 nm), compared to those of the control group. However, the scleral collagen fibrils treated with 0.02% mitomycin C for three and five minutes showed significant increases in mean fibril diameter (182.33 +/- 16.33 nm, 199.20 +/- 12.40 nm, respectively) and mean D-periodicity (70.27 +/- 13.66 nm, 72.75 +/- 19.32 nm, respectively), compared to those of the control group. CONCLUSIONS: The present study examined the structural changes in the scleral collagen fibrils before and after mitomycin C application according to atomic force microscopy. The results indirectly suggest that three or more minutes of 0.02% mitomycin C application affects the morphology of scleral collagen.
Collagen ; Humans ; Microscopy, Atomic Force ; Mitomycin ; Sclera

We investigated the effect by the chemical fixative on human fibroblast cells (HFCs) in order to make nano-scale images using by the atomic force microscopy (AFM). The cell fixation needed to be optimized as prerequisite step for the preparation before analysis. AFM imaging after optimal wet fixation can provide practical, simple and fast technique for scanning living cells. In this study, AFM images - topography and amplitude - and the optic images of HFCs which were fixed with phosphate buffered saline (PBS), 2:1 ethanol:acetic acid, 4% glutaraldehyde and 37% formaldehyde were compared respectively. The final effect by washing with PBS or distilled water (D.W.) was examined after 4% glutaraldehyde fixation. To determine the optimal fixation method for HFCs, we performed quantitative and qualitative analysis by the height profile, the presence of artifacts and the morphology of well-conserved fibroblastic topography image by AFM. From AFM image which showed fibroblastic cellular morphology and differential height value of cytoplasm (670+/-47 nm, n=10) and nucleus (847+/-32 nm, n=10) in HFCs, we proposed that wet fixation by 4% glutaraldehyde, followed by final washing with PBS, could be the most suitable preparation for AFM imaging of HFCs, which enable us to approach easily on living cells with the least shrinkage.
Artifacts ; Cytoplasm ; Fibroblasts ; Formaldehyde ; Glutaral ; Humans ; Microscopy, Atomic Force ; Water

OBJECTIVEThis study is conducted to explore new methods to perform surface biomodification of titanium implants and improve osteogenic efficiency.

METHODSAn RGD peptide and chitosan (CS) were combined by acylation reaction, forming RGD-CS. An RGD-CS/pDNA complex was subsequently prepared using a complex coacervation method and grafted on a pure titanium surface after physical and biochemical treatments were performed. The chemical structural characteristics of RGD-CS were evaluated using an infrared spectrometer and an elemental analyzer. The shape of this complex was then assessed by gel electrophoresis combined with atomic force microscopy. The grafting effect of this complex on the titanium surface was detected by EB staining.

RESULTSCS and RGD peptides were coupled by an amide bond. The RGD-CS/pDNA complex was completely composited at N/P > or = 2. Atomic force microscopy results showed that the morphology of this complex was mainly spherical. EB staining experiments showed that this complex was successfully grafted on the titanium plate.

CONCLUSIONRGD peptide-modified CS can be used as a titanium implant surface plasmid package carrier of pDNA.

Endothelial cells (ECs) with a variety of functions are vulnerable to attack by various risk factors. These risk factors of vascular pathology lead to endothelial dysfunction (ED). However, the present methods of evaluating ED have their limitations. Atomic force microscope (AFM), which can offer the information on the surface images and the mechanical properties of the single cell at nanometer scale, will become a new technical approach to ED evaluation. This review focuses on the recent progress in the application of AFM to assess ED.
Endothelial Cells ; cytology ; physiology ; Humans ; Microscopy, Atomic Force ; methods

OBJECTIVETo investigate the effects of acute hypervolemic hemodilution (AHH) and intraoperative blood salvage (IOBS) on the morphology and biomechanics of erythrocytes using atomic force microscopy (AFM).

METHODSBlood samples were collected from 20 patients undergoing orthopedic surgery before operation (T1), immediately after AHH (T2), and after blood salvage (T3). AFM at nanometer resolution was used to examine the morphology and biomechanics of the collected erythrocytes.

RESULTSThe blood samples collected at T1 showed a significantly lower ratio of heteromorphous erythrocytes than those collected at T2 and T3 [(2.6∓1.3)% vs (19.3∓1.6)% and (17.6∓1.4)%, P<0.05]. AFM revealed significant differences in the morphology and biomechanics of the single erythrocyte in salvaged blood and blood after AHH compared with those of venous blood.

CONCLUSIONAHH and IOBS may cause significant changes in the morphology and biomechanics of erythrocytes in the salvaged blood.

OBJECTIVE: This study was designed to measure the surface roughness at the slot floor of various ceramic brackets. METHODS: One kind of stainless steel bracket (Succes(R)), two kinds of monocrystalline brackets (Inspire Ice(R), Perfect(R)) and two kinds of polycrystalline brackets (Crystalline V(R), Invu(R)) were examined. Atomic force microscopy (AFM) was used to measure the surface roughness of each bracket. Data acquisition and processing were performed using SPIP(TM). RESULTS: The differences in values of Sa, Sq, and Sz in Invu(R) and Inspire Ice(R) were not statistically different from the control group Succes(R). The values of Sa, Sq, and Sz of Perfect(R) and Crystalline V(R) were greater than those of Succes(R). Differences of all the Sa, Sq, and Sz values between Perfect(R) and Crystalline V(R) were not statistically significant. CONCLUSIONS: It is concluded that the slot surfaces of Succes(R), Inspire Ice(R), and Invu(R) were smooth compared to those of Crystalline V(R) and Perfect(R).
Ceramics ; Crystallins ; Floors and Floorcoverings ; Microscopy, Atomic Force ; Stainless Steel

OBJECTIVE: The surface roughness of orthodontic materials is an essential factor that determines the coefficient of friction and the effectiveness of tooth movement. The aim of this study is to evaluate the surface roughness change of the brackets and wires after experimental sliding quantitatively. METHODS: Before and after experimental sliding tests, the surface roughness of stainless steel brackets, ceramic brackets, stainless steel wires, and beta-titanium (TMA) wires were investigated and compared using atomic force microscopy (AFM). RESULTS: After sliding tests, changes in the surface of the wire were greater than changes in the bracket slot surface. The surface roughness of the stainless steel bracket was not significantly increased after sliding test, whereas the roughness of ceramic brackets was decreased. Both the surface roughness of stainless steel and TMA wires were increased after sliding test. More changes were observed on the ceramic bracket than the stainless steel bracket. CONCLUSIONS: AFM is a valuable research tool when analyzing the surface roughness of the brackets and wires quantitatively.
Ceramics ; Friction ; Microscopy, Atomic Force ; Stainless Steel ; Tooth Movement

OBJECTIVETo observe the surface of Enterococcus faecalis and the dynamic forming process of those biofilms using atomic force microscopy (AFM) in air condition.

METHODSThe surface of Enterococcus faecalis which were dried in air were observed with AFM. We used the cellulose nitrate film to construct the Enterococcus faecalis biofilms model in vitro, and then placed the biofilms under AFM to observe the surface changes of biofilms' development.

RESULTSThe cell surfaces of strain Enterococcus faecalis were not regular because of the presence of the amorphous substance on the colony surface, which congregated globular, fibrous structure. Gradually determined that at 6 h the initial biofilm formed and at 24 h the biofilms maintained the steady-state. AFM height images showed topographical changes due to biofilms' development, which were used to characterize several aspects of the bacterial surface, such as the presence of extracellular polymeric substance, and the biofilms' development stage.

CONCLUSIONApplication of AFM in physiological conditions could be useful in observing Enterococcus faecalis surface ultrastructure and dynamic process of biofilms formation.

In recent years, the applications of atomic force microscopy (AFM) have underpinned the fast progress in the area of tissue engineering. Besides the study of surface morphology in the dimension of micro- and nano-, AFM has played an important role in the fabrication of micro- and nano-structure as well as in the investigation of mechanical properties of material and cell. This overview is aimed to introduce the principle of AFM and to review its recent applications in tissue engineering.
Humans ; Microscopy, Atomic Force ; Nanotechnology ; Tissue Engineering ; trends ; Tissue Scaffolds