Probe microscopy methods and applications in imaging of biological materials

Abstract

Atomic force microscopy is an emerging tool for investigating the biomolecular aspects of cellular interactions; however, cell and tissue analyses must frequently be performed in aqueous environment, over rough surfaces, and on complex adhesive samples that complicate the imaging process and readily facilitate the blunting or fouling of the AFM probe. In addition, the shape and surface chemistry of the probe determine the quality and types of data that can be acquired from biological materials, with certain information becoming available only within a specific range of tip lengths or diameters, or through the assistance of specific chemical or biological functionalization procedures. Consequently, a broad range of probe modification techniques has been developed to extend the capabilities and overcome the limitations of biological AFM measurements, including the fabrication of AFM tips with specialized morphologies, surface coating with biologically affine molecules, and the attachment of proteins, nucleic acids and cells to AFM probes. In this review, we underline the importance of probe choice and modification for the AFM analysis of biomaterials, discuss the recent literature on the use of non-standard AFM tips in life sciences research, and consider the future utility of tip functionalization methods for the investigation of fundamental cell and tissue interactions.

Nanoindentation of Soft Biological Materials

“…In spite of the wide application of spherical and flat-ended tips for characterizing soft biomaterials, each one has its own advantages and drawbacks, and may be more applicable to specific conditions, as shown in Table 2. The reader is also encouraged to review more details about different tips in the literature [82,95].…”

Lipid Self-Assemblies under the Atomic Force Microscope

“…Thus, tip or cantilever fouling is a recurring problem for AFM users as it often generates artifacts and requires immediate washing of the tip/cantilever or, usually, a replacement with a clean new one. Tip functionalization (i.e., the chemical modification of the AFM tip with a specific agent) is also a common way to limit undesired interactions [ 87 ].…”

Methods to probe the formation of biofilms: applications in foods and related surfaces

“…Examples can be found in a series of reviews. [101][102][103][104][105][106] Topography examination with AFM has been widely used for visualization of single cells and biolms on food contact surfaces with high resolution and sensitivity. Table 3 summarizes some of the studies in food processing.…”