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The scanning near-field optical microscopy imaging of specimens in liquid and of cultured cells in aqueous solutions is reported. A scanning near-field optical/atomic-force microscope (SNOM-AFM) was developed, in which the scanning of an optical-fiber probe cantilever over the specimen was controlled by noncontact mode AFM (dynamic mode AFM). This imaging mode reduces damage to the probe and soft specimens. The resonant frequency of the probe cantilever decreased 20% to ≊14 kHz and the Q factor decreased by a factor of 8 to ≊30 in water, compared with these values in air, which was sufficient to perform SNOM-AFM imaging in liquid.

High-stability sensing of proteins of pig serum albumin (PSA) was achieved using an insulator-covered carbonnanotube field-effect transistor (CNT-FET) with a top-gate structure. The sensitivity limit of this CNT-FET PSA sensor is at least 5 nmol/L PSA solution. A layer of silicon nitride deposited on the top-gate structure provides an n-type characteristic and a highly stable CNT-FET. Since the CNT is covered with a silicon nitride layer, it is isolated from oxygen, water, and other contaminants. The equilibrium constant of the PSA/ anti-PSA reaction, which indicates the strength of the binding energy between PSA and anti-PSA fixed on the Au top-gate electrode, was calculated to be 1.2 × 10 7 L/mol using the Langmuir equation fitting.

A new method for the acid hydrolysis of protein is presented. Peptide bonds are cleaved by the action of an HCl/trifluoroacetic acid (TFA) vapor mixture. Contamination for the hydrolysis mixture is reduced to low levels (1-3 pmol). Recovery of hydrophobic amino acid is improved. Short reaction times are achieved and rapid removal of acids is facilitated. The reaction temperature is 158 degrees C for reaction times of 22.5 and 45 min with 7 M HCl and 10% TFA containing 0.1% phenol.

Recent reports by Neff et al. have shown a method of preparation of Prussian blue (PB) on platinum and gold electrodes based on a chemical method.1•2 We disclosed very recently an elec-

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An easy calibration method based on the Langmuir adsorption theory is proposed for a carbon nanotube field-effect transistor (NTFET) biosensor. This method was applied to three NTFET biosensors that had approximately the same structure but exhibited different characteristics. After calibration, their experimentally determined characteristics exhibited a good agreement with the calibration curve. The reason why the observed characteristics of these NTFET biosensors differed among the devices was that the carbon nanotube (CNT) that formed the channel was not uniform. Although the controlled growth of a CNT is difficult, it is shown that an NTFET biosensor can be easy calibrated using the proposed calibration method, regardless of the CNT channel structures.