Atomic Force Microscopy

Bruker AFM Multimode

Bruker AFM Multimode is a general purpose atomic force microscope for contact or tapping mode imaging, with a wet-cell capable of imaging in a liquid environment.

WITec alpha500 Raman-AFM Microscope

The WITec alpha500 combines Confocal Raman Microscopy for 3-D Chemical Imaging and Atomic Force Microscopy for high resolution structural imaging in an automated system. It not only allows high resolution surface topography imaging with AFM at many different sample positions but also Raman Imaging, large area Raman scans and multi-point spectra acquisition at a user-defined number of measurement points. The Raman and AFM images of the same sample positions can then be matched and linked together for a comprehensive understanding of the sample's properties.

TECHNICAL SPECIFICATIONS

• 3 Lasers excitation sources (532 nm, 633 nm and 785 nm) with a multi-laser coupling unit for a maximum of experimental flexibility
• Multiple objective selections including air (10x, 20x, 50x and 100x), water immersion (63x) and oil immersion (100x) objectives
• A piezo stage (200 μm x 200 μm) coupled with a motorized microscope stage (10 cm x 15 cm) to allow for high-resolution confocal Raman mapping and large area investigations
• Polarization dependent measurements
• Research-grade optical microscope body with LED Köhler white-light illumination and video camera sample view
• AFM mode: contact, AC and Pulsed Forced mode

Project 1: Peter Vikesland, co-PI

Controlled Evaluation of Nanoparticle Dissolution Using Atomic Force Microscopy

The safety issues with nanoparticles are continuously being tested since their potential dangers for the environment and human health. Dissolution of nanoparticles is an important process that alters their properties and is also a critical step in determining safety of nanoparticles. Distinguishing the toxicity of nanoparticles in particle form relative to that of the released ions is a critical but challenging research topic. Studying nanoparticle dissolution as illustrated herein can help in the current move toward safer design and application of nanoparticles. Environmental risk assessments of engineered nanoparticles require characterization of nanoparticles and quantitative analytical methods to determine environmental concentrations. The effect and exposure of engineered nanoparticles are vital for the development of related products. In this project, the uniform arrays of nanoparticles enable the controlled evaluation of nanoparticle dissolution in the absence of aggregation. We tracked the height changes of AgNPs fabricated on glass slides using Atomic Force Microscope (AFM). The controlled evaluation of height changes were obtained by AFM measurements. The effects of surface coating on nanoparticle dissolution were illustrated in the absence of aggregation. Information obtained from this study demonstrated different coating agents exhibit various effects on the dissolution process. Specifically, the PEG coating prevents the AgNPs from dissolving in 2 weeks which lead almost no Ag+ released to the solution. For BSA coated samples, slight changes were observed for the shape and height. The results of this work will aid efforts to engineer environmentally benign nanomaterials and to predict the environmental impacts of coated NPs.      

Figure 1 (a) Schematic of AgNP array production and coating process, (b) AFM image of original AgNPs, and (c) AgNP height distribution as measured by AFM. The mean height of 585 particles was 47.1 with a standard deviation of 1.5 nm.

Liu, C., Leng, W., Vikesland, P. J., Controlled Evaluation of the Impacts of Surface Coating on Silver Nanoparticle Dissolution Rates, ES&T, 2018, 52(5),2726-2734.

Coming soon...