Progress of AFM single-cell and single-molecule morphology imaging

Abstract

Atomic force microscopy (AFM) can probe single living cells and single native membrane proteins in natural fluid environments with label-free high spatial resolution. It has thus become an important tool for cellular and molecular biology that significantly complements traditional biochemical and biophysical techniques such as optical and electron microscopy and X-ray crystallography. Imaging surface topography is the primary application of AFM in the life sciences. Since the early 1990s, researchers have used AFM to investigate morphological features of living cells and native membrane proteins with impressive results. Steady improvements in AFM techniques for imaging soft biological samples have greatly expanded its applications. Based on the authors' own research in AFM imaging of living cell morphologies, a review of sample preparation procedures for single-cell and single-molecule imaging experiments is presented, along with a summary of recent progress in AFM imaging of living cells and native membrane proteins. Finally, the challenges of AFM high-resolution imaging at the single-cell and single-molecule levels are discussed.

Nanoscale Quantifying the Effects of Targeted Drug on Chemotherapy in Lymphoma Treatment Using Atomic Force Microscopy

“…For AFM imaging, Raji cells (treated by different drug combinations in cell incubator) from the 24-well culture plates were dropped onto the glass slides which were coated by poly-L-lysine. The role of poly-L-lysine was attaching cells onto the substrate via electrostatic adsorption [12]. Raji cells on the glass slides were then chemically fixed by 4% paraformaldehyde for 30 min.…”

“…moisture, currently its spatial resolution is low and is still unable to image living cells in physiological conditions [12]. In recent years, the applications of atomic force microscopy (AFM) in observing nanoscale cellular activities have contributed much to the field of cell biology [13], [14].…”

Applications of Atomic Force Microscopy in Exploring Drug Actions in Lymphoma-Targeted Therapy at the Nanoscale

“…Adherent cells can naturally grow and spread on the substrate (e.g., glass slide and Petri dish); thus, we can directly perform AFM scanning on them without extra immobilization. Microbial cells are small and have stiff cell wall; thus, we can obtain highresolution AFM images on them with the immobilization of porous polymer membrane or poly-L-lysine electrostatic adsorption [21]. Mammalian suspended cells are soft and have large size, causing the porous polymer membrane method or pure electrostatic adsorption unsuitable.…”

Progress in measuring biophysical properties of membrane proteins with AFM single-molecule force spectroscopy

“…In SMFS mode, AFM can be used to measure affinities, distributions, and unfolding dynamics of membrane proteins. The wide applicability of AFM in biology yields considerable knowledge with regard to cellular activities [70][71][72][73][74], considerably promoting the progress of nanobiotechnology [22]. Although SMFS has been an important way to measure biophysical properties of membrane proteins, several challenges remain.…”

“…In summary, SMFS has made significant contributions in understanding the biophysical properties of membrane proteins, but still faces challenges requiring researchers from different disciplines to work together to solve. Improvements in AFM continue to occur, such as high-speed AFM, non-contact mode imaging [23], and combination imaging with other methods such as fluorescence microscopy and patch clamp signaling [71]. These techniques will expand the application of AFM in biology and will enable tremendous progress in structural biology and biophysics.…”