In recent years there has been great progress in applying FET-type biosensors for highly sensitive biological detection. Among them, the ISFET (ion-sensitive field-effect transistor) is one of the most intriguing approaches in electrical biosensing technology. Here, we review some of the main advances in this field over the past few years, explore its application prospects, and discuss the main issues, approaches, and challenges, with the aim of stimulating a broader interest in developing ISFET-based biosensors and extending their applications for reliable and sensitive analysis of various biomolecules such as DNA, proteins, enzymes, and cells.

Chemical reactions that occur in the ground electronic state are described well by invoking the Born-Oppenheimer approximation, which allows their development to be rationalized by nuclear rearrangements that smoothly traverse an adiabatic potential energy surface. The situation is different, however, for reactions in electronically excited states, where non-adiabatic transitions occur between adiabatic surfaces. The conical intersection, in which two adiabatic surfaces touch, is accepted widely as the dynamic funnel for efficient non-adiabatic transitions, but its direct experimental probing is rare. Here, we investigate the photodissociation of thioanisole and observe a striking dependence of the relative yields of two reaction channels on the photoexcitation energy as indicated by a dynamic resonance in the product branching ratio. This results from the interference of two different adiabatic states that are in close proximity in the region of a conical intersection. The location of the observed resonance on the multidimensional potential energy surface thus reveals the nuclear configuration of the conical intersection and its dynamic role in the non-adiabatic transition.

TiO 2 nanoparticles were prepared by hydrothermal reaction of titanium alkoxide stabilized in acidic ethanol/water solution. The sizes of particles have been controlled to the range of 7-25 nm by adjusting the concentration of Ti precursor and the composition of the solvent system. The TiO 2 samples synthesized under this acidic ethanol/water environment were mainly primary particles in anatase phase without secondary structure. The suspension of as-prepared 7-nm-sized TiO 2 nanoparticles demonstrates long-term stability, and has been applied successfully for the fabrication of ultra-transparent particulate TiO 2 films. The photocatalytic efficiency of TiO 2 films prepared from the 7-nm-sized nanoparticles was 1.6 times of that of films derived from Degussa P25 in decomposing gaseous 2-propanol.

Many molecules can rotate freely around single bonds and thereby interconvert between different conformations, such as gauche and anti 1,2-disubstituted ethane, a classic example of conformational isomerism. Even though rotation occurs rapidly at room temperature, the product selectivity seen in some reactions has been explained by conformation-dependent reaction mechanisms: if reactant molecules differing only in their conformation are located at different positions on the reaction path, they may undergo different reactions. But a direct verification of this effect is difficult, because the energy barrier separating conformational isomers is so low that under ambient conditions reactants with more than one conformation will be present. But by using temperatures low enough to suppress the interconversion between different conformations, gauche-1-iodopropane ions and anti-1-iodopropane ions have been selectively generated. Here we show that the kinetic energy released during the photodissociation of 1-iodopropane ions depends strongly on the conformation of the ions. Thermodynamic arguments and ab initio calculations indicate that this difference in kinetic energy release results from differences in the reaction mechanism, with gauche-1-iodopropane ions forming 2-propyl ions and anti-1-iodopropane ions forming protonated cyclopropane ions. These findings suggest that the well-known concept of conformation selection forms the basis of a simple scheme for reaction control, thus providing in some cases an attractive alternative for more involved schemes that utilize the phase and pulse shape of laser beams to control chemical reactions.