Microscopy chemical force

Chemical force microscopy (CFM) refers to the chemical modification of the AFM tip with specific functional groups to measure the forces involved in chemically specific interactions with a surface. It is implemented in lateral force microscopy, force spectroscopy (force curve), and force- 

Chemical force microscopy showed the surface reconstruction of low density polyethylene (LDPE) oxidized with chromic acid (in conjunction with contact-angle measurements) [71] and the aging of melt-pressed films of PP 

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Noy, A., Frisbie, C.D., Rozsnyai, L.F., Wrighton, M.S. and Lieber, C.M., Chemical force microscopy — exploiting chemically modified tips to quantify adhesion, friction, and functional-group distributions in molecular assemblies. J. Am. Chem. Soc., 117(30), 7943-7951 (1995). 

In summary, chemical force microscopy appears to be a powerful tool for the study of adhesion on the nanoscale provided that issues such as the detrimental influence of mechanical effects, substrate roughness, packing density, unknown tip radius, and reliance on statistical analysis can somehow be resolved in a consistent and logical way. 

Nature takes various approaches to adhesion, the most common being to control contact area through deformation of a multitude of hairlike fibrils or alternatively to modify the surface property in a way analogous to chemical force microscopy. These processes have been... 

Chemical force microscopy (CFM) [26] is a progression from the physicochemical based detection of LFM to specific chemical detection. CFM performs the nanoscale chemical analysis of the sample, through the measurement of forces related to specific chemical interaction between a chemically functionalised tip (e.g., with carbon nanotubes or oligonucleotides) and a surface that is chemically functionalised with complementary (or non-complementary) chemical species, e.g., complementary oligonucleotides. 

Lately one has been able to encounter experimental studies more frequently denoted Chemical Force Microscopy , CMF. This includes various attempts to observe tip-surface interactions which are specific to the chemical constitution of the surface. Mostly, CFM involves modification of the tip by a surface layer with molecules which contain particular functional groups, i.e. hydrophilic or hydro-phobic moieties, hydrogen bonding groups, ionic substituents and molecular units which can undergo electron-donor-acceptor interactions. However, sometimes the term Chemical Force Microscopy is just used for any method which can provide a material specific contrast. Depending on the specificity, CFM provides valuable information on the nanoscale composition complementary to other surface characterisation methods which are sensitive to the chemical con-... 

Over the last few years, chemical modification of the tips has attracted a lot of attention because of their application for chemical force microscopy. Different methods have been developed to functionalise a SFM-tip with either hydrophobic or hydrophilic molecules. Most of them are based on the monolayer self-as-... 

Chemical Force Microscopy. AFM experiments can be performed using probes that have been derivatized with specific chemical functional groups. These proximal probes allow for the detection and utilization of specific probe-sample interactions as a means of obtaining chemical contrast in AFM images, and this technique is commonly known as chemical force microscopy.175 Chemical force microscopy represents an extrapolation to very short (i.e., nanometer) length... 

SOURCE Reprinted with permission from Noy, A., C.H. Sanders, D.V. Vezenov, S.S. Wond, and C.M. Lieber. 1998. Chemically sensitive imaging in tapping mode by chemical force microscopy Relationship between phase lag and adhesion, Langmuir 14 1508-1511. Copyright 1998 American Chemical Society. 

Hillborg, H., N. Tomczak, A. Olah, H. Schonherr, and G.J. Vansco. 2004. Nanoscale hydrophobic recovery A chemical force microscopy study of UV/ozone-treated cross-linked poly(dimethylsiloxane). Langmuir 20 785-794. 

Fiorini, M., McKendry, R., Cooper, M. A., Rayment, T., and Abell, C. (2001) Chemical Force Microscopy with active enzymes, Biophys. J., 80, 2471-2476. 

Another AFM-based technique is chemical force microscopy (CFM) (Friedsam et al. 2004 Noy et al. 2003 Ortiz and Hadziioaimou 1999), where the AFM tip is functionalized with specific chemicals of interest, such as proteins or other food biopolymers, and can be used to probe the intermolecular interactions between food components. CFM combines chemical discrimination with the high spatial resolution of AFM by exploiting the forces between chemically derivatized AFM tips and the surface. The key interactions involved in food components include fundamental interactions such as van der Waals force, hydrogen bonding, electrostatic force, and elastic force arising from conformation entropy, and so on. (Dther interactions such as chemical bonding, depletion potential, capillary force, hydration force, hydrophobic/ hydrophobic force and osmotic pressure will also participate to affect the physical properties and phase behaviors of multicomponent food systems. Direct measurements of these inter- and intramolecular forces are of great interest because such forces dominate the behavior of different food systems. 

See scanning tunneling microscope chemical force microscopy. 

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