Langmuir-Blodgett (LB) films of bacteriorhodopsin (bR) without addition of lipids were deposited on indium tin oxide (ITO) conductive electrodes. A sandwich photocell with a junction structure of ITO/bR/electrolyte/lTO has been constructed in which the bR LB film was put into contact directly with an aqueous electrolyte immobilized in an agar gel. Under visible light irradiation a transient photocurrent due to a change in light intensity can be observed, showing the property of vision-imitative material. It can be used as a multiple optical switch, since it gives positive and negative transient photocurrents during application and removal of light irradiation respectively and has a photoresponse repeatedly in the same direction when the light intensity increases or decreases stepwise. A photoalarm consisting of the bR photocell and an amplifier was set up by utilizing the switching function of the bR LB film.

A simple method is used to control the size of cetyltrimethylammoniumbromide-protected Au nanoparticles by a reversal micelle in safe organic solvent. These Au nanoparticles can be evolved to highly monodisperse Au nanoparticles capped 1-dodecanthiol in the 2, 3, and 5 nm diameter by refluxing at 1608 8 8 8 8C for 7 hours. Their ultraviolet visible spectroscopy (UV-vis), x-ray diffraction (XRD, transmission electron microscopy (TEM) showed that all the three different size gold nanoparticles(NPs) displayed high size homogenous properties and easy formed large areas of long ordered two-dimensional arrangement at the air/solid interface.

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