Nanotechnology is stimulating the development of nanomanipulators, including tips to interact with individual nanosystems. Fabricating nanotips fulfilling the requirements of shape (size, aspect ratio), mechanical, magnetic, and electrical properties is a material science challenge. Here, we report the generation of reinforced carbon-carbon composite nanotools using a nanotube (CNTs) covered by an amorphous carbon matrix (shell); the CNT tip protruded and remained uncoated to preserve apex size. Unsuitable properties such as flexibility and vibration could be controlled without deteriorating the CNT size, strength, and resilience. Nanomanipulation experiments and molecular dynamics simulations have been used to study the mechanical response of these composite beams under bending efforts. AFM probes based on these C-C composite high aspect ratio tips generated excellent image resolution and showed no degradation after acquiring several hundred (400) images.
Nanomechanical biosensors based on atomic force microscopy (AFM) cantilevers have garnered considerable attention. AFM cantilevers are devices that can detect a target either via a surface functionalization process based on immobilization through molecular adsorption, or through the selective chemical binding of a speci¯c molecule, transforming the device into a speci¯c biosensor. In this study, we demonstrate that functionalized AFM cantilevers could be used, in a process involving self-assembling layers, to create a homogeneous surface layer of the widely used herbicide mesotrione. Controlled experiments to evaluate its detection were performed, and binding between mesotrione and its target molecule, 4-hydroxyphenylpyruvate dioxygenase (HPPD), was evaluated using de°ection curves of functionalized cantilevers interacting with mesotrione. The cantilevers worked as nanomechanical sensors inside a°uid cell device, under di®erent ¶ Corresponding author.
1750079-1NANO: Brief Reports and Reviews Vol. 12, No. 7 (2017) concentrations of HPPD diluted in PBS. After evaluating increasing concentrations of HPPD, the de°ection curves showed a clear, dose-dependent pattern. The homogeneous dispersion of mesotrione on the cantilevers was assessed by confocal microscopy, and this corroborated the functionalization method. Thus, the results obtained by this functionalized cantilever presented a high e±ciency in detecting binding between HPPD and mesotrione molecules at concentrations as low as 17 ng mL À1 . In this way, as a preliminary step for a future environmental contaminants nanosensor development, the described detection method showed a suitable capability for molecular recognition at the nanoscale.
We have investigated the growth process of Xylella fastidiosa biofilms inoculated on a glass. The size and the distance between biofilms were analyzed by optical images; a fractal analysis was carried out using scaling concepts and atomic force microscopy images. We observed that different biofilms show similar fractal characteristics, although morphological variations can be identified for different biofilm stages. Two types of structural patterns are suggested from the observed fractal dimensions Df. In the initial and final stages of biofilm formation, Df is 2.73±0.06 and 2.68±0.06, respectively, while in the maturation stage, Df=2.57±0.08. These values suggest that the biofilm growth can be understood as an Eden model in the former case, while diffusion-limited aggregation (DLA) seems to dominate the maturation stage. Changes in the correlation length parallel to the surface were also observed; these results were correlated with the biofilm matrix formation, which can hinder nutrient diffusion and thus create conditions to drive DLA growth.
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