We used atomic force microscope (AFM) to acquire high-resolution images of collagen type I triple-helices under ambient conditions in tapping mode. Angles between consecutive fixed-length segments were measured and analyzed to yield persistence length and elastic constant. Changing the segment length allowed exploring the mechanics at various scales. Understanding the mechanical properties of collagen molecules could serve to elucidate mechanisms of complex mechanical properties of interest in nanomedicine and nanotechnology.

By incorporating a localized heating system within a scanning ion-conductance microscopy (SICM) system, we have performed stable ‘hopping-mode’ (HPICM) imaging for live cells maintained at temperatures ranging up to human body temperature. This allows the accurate study of cell volume and morphology variation versus temperature over extended periods of time. The integration of SICM with scanning electrochemical microscopy (SECM) provides the simultaneous mapping of electrochemical and topographic information for soft samples, such as live cells. This combined technique overcomes the limitations of resolution and topographical artifacts typically associated with SECM. However, previously reported SECM-SICM probe production required expensive and time-consuming focused ion beam (FIB) methods and produced pipettes that are typically hundreds of nanometers in diameter. We report a simple and rapid production method for SECM-SICM double-barrel probes with apertures down to 20 nm in diameter. The characterization of these SECM-SICM probes using scanning electron microscopy (SEM) imaging, cyclic voltammetry (CV) and Raman spectroscopy is also detailed. These SECM-SICM probes were subsequently used to study the morphology and electrochemical activity of several samples, ranging from hard metallic/insulating samples to live cells.

Using AFM, ellipsometric and profilometric measurements, we have investigated the topography and the thickness of the cellulose nanocristal (NCC) films prepared by two different methods: the first one is obtained by evaporation of concentrated suspension of NCC in petri-dish to produce a self-supported film; the second one is produced by dipping thin NCC layer on silicon substrate by Langmuir-Blodgett (LB) technique. Glucomanan (GM) functionalized AFM tip was brought into contact with these two kinds of NCC films in order to measure the adhesion between GM and NCC. The impact of the substrate and the thickness of NCC films on the measured adhesion forces were also studied: the mean measured adhesion force between the two polysaccharides was 17 nN regardless of the way the films were prepared. Adhesion properties can help us understand biochemical processes in the plant cell wall.

Multi-frequency atomic force microscopy (AFM) offers additional response signals in comparison to traditional dynamic AFM. Furthermore, depending on the mode of operation used, the higher eigenmode responses are generally not directly influenced by the topographical acquisition control loops, such that they can explore a fuller range of tip-sample interactions. In this work we describe the implementation of multi-frequency imaging schemes that enable the acquisition of topographical, phase and frequency shift contrast in tapping-mode operation. This type of characterization can be especially useful for soft, highly dissipative samples, such as polymers, for which the various response channels can exhibit significantly different response, thus providing complementary information. We discuss typical results obtained as well as important challenges that need to be addressed in order to develop a fully quantitative technique.