Vibration response of an atomic force microscopy piezoelectrically actuated microcantilever in liquid environment

AbstractFerritin, a protein that is present in the human body for a controlled iron storage and release, consists of a ferrihydrite core and a protein shell. Apoferritin, the empty shell of ferritin, can be modified to carry tailored properties exploitable for targeted and direct drug delivery. This protein shell has the ability to dis- and reassemble depending on the pH value of the liquid environment and can thus be filled with the desired substance. Here we observed the dis- and reassembly process of the protein shell of ferritin and apoferritin in situ and in real space using atomic force microscopy. Ferritin and apoferritin nanoparticles adsorbed on a mica substrate exhibited a change in their size by varying the pH value of the surrounding medium. Lowering the pH value of the solution led to a decrease in size of the nanoparticles whereas a successive increase of the pH value increased the particle size again. The pH dependent change in size could be related to the dis- and reassembling of the protein shell of ferritin and apoferritin. Supplementary imaging by bimodal magnetic force microscopy of ferritin molecules accomplished in air revealed a polygonal shape of the core and a three-fold symmetry of the protein shell providing valuable information about the substructure of the nanoparticles.

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Wideband low-noise optical beam deflection sensor with photothermal excitation for liquid-environment atomic force microscopy

Review of Scientific Instruments ◽

10.1063/1.3086418 ◽

2009 ◽

Vol 80 (2) ◽

pp. 023707 ◽

Cited By ~ 95

Author(s):

Takeshi Fukuma

Keyword(s):

Atomic Force Microscopy ◽

Low Noise ◽

Optical Beam ◽

Beam Deflection ◽

Liquid Environment ◽

Force Microscopy ◽

Atomic Force

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Modification of a commercial atomic force microscopy for low-noise, high-resolution frequency-modulation imaging in liquid environment

Review of Scientific Instruments ◽

10.1063/1.3606399 ◽

2011 ◽

Vol 82 (7) ◽

pp. 073703 ◽

Cited By ~ 24

Author(s):

S. Rode ◽

R. Stark ◽

J. Lübbe ◽

L. Tröger ◽

J. Schütte ◽

...

Keyword(s):

Atomic Force Microscopy ◽

High Resolution ◽

Frequency Modulation ◽

Low Noise ◽

Liquid Environment ◽

Force Microscopy ◽

Atomic Force

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Bovine Serum Albumin Adhesion Force Measurements Using an Atomic Force Microscopy

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.32.49 ◽

2008 ◽

Vol 32 ◽

pp. 49-52 ◽

Cited By ~ 1

Author(s):

Chun Chih Lai ◽

John M. Bell ◽

Nunzio Motta

Keyword(s):

Atomic Force Microscopy ◽

Bovine Serum Albumin ◽

Serum Albumin ◽

Bovine Serum ◽

Adhesion Force ◽

Direct Method ◽

Substrate Surface ◽

Liquid Environment ◽

Force Microscopy ◽

Atomic Force

A new, direct method has been developed to measure the adhesion forces of bovine serum albumin (BSA) on surfaces by using Atomic Force Microscopy (AFM) in liquid environment. We were able to measure interactions between proteins and substrate surface in PBS solution directly without any modification to the substrate or the AFM tip. Two different surfaces have been used in the experiments: mica (hydrophilic surface) and polystyrene (hydrophobic surface). The results show that a polystyrene surface is more adhesive to BSA than a mica surface. This is consistent with previous research, which assessed that hydrophobic surfaces enhance protein adhesion but hydrophilic surfaces do not, demonstrating the effectiveness of the technique.

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