Molecular imaging technologies visualizing intracellular molecular events in living subjects have greatly advanced in the past two decades. The technological achievements contributed by establishment of excellent optical readouts including fluorescent proteins and luciferases, which are expanding its industrial utilisation. Nowadays, fluorescent proteins are optimally geared to optical instrumentation equipped with a camera and a laser, and thus some of the recently advanced instrumentation is even able to access single-molecule imaging. Meanwhile, bioluminescent means including firefly luciferase are also emerging their industrial usages as an optical readout of antibodies, a bioluminescence imaging (BLI) tool, and other bioassays. This molecular imaging technology has clearly distinctive advantages from conventional living subject imaging technologies like nuclear magnetic resonance (MRI), positron emission tomography (PET), computed tomography (CT), ultrasound, etc, with respect to the quantitative and pinpoint-imaging properties of a specific molecular event in living subjects. In contrast, conventional molecular imaging technologies share the common drawbacks such as nonspecific, physical, qualitative properties upon imaging of the molecular events (e.g., nuclear spins, radio isotopes, ultrasounds) with low sensitivity. The present article briefly reviews the recent achievements of luciferase-based molecular imaging technologies.
Barrier function and water content are among the most important areas in the field of cosmetics. These skin parameters are usually measured by using quantitative devices, however, evaluation with these contact-measurement devices is limited to single-point measurement. Recently, the barrier function of the stratum corneum was visualized by topically applying fluorescein to the skin surface and the water content was visualized by using near infrared (NIR) cameras. These visualizing techniques enabled the acquisition of two-dimensional (2D) information of the skin conditions.
In clinical fields, cancer diagnosis and therapy using photosensitizer are established. These methods are named photodynamic therapy (PDT) and photodynamic diagnosis (PDD), respectively. Recent activity has created a number of photosensitizer for PDT and PDD. In this article, recent progress of PDT and PDD are introduced.
Defects in products and the physical properties of materials can be visualized or evaluated by ultrasound. This is because ultrasound is reflected at the discontinuity and the sound velocity is related with elasticity of materials. First, this article shows that very thin defects can be visualized by ultrasound. Dry-contact ultrasonic technique, which visualizes the internal structure in a sample without getting the sample wet, is introduced. Moreover, changes in the physical properties of a polymer film due to the thermal degradation can also be detected by ultrasound.
The large scale facilities have been provided neutron beam and its instruments. RIKEN has developed compact accelerator-driven neutron source system for the practical use. The visualization of rust and the related moisture reduction in the steel under the film was succeeded with RIKEN accelerator-driven compact neutron source RANS. The non-destructive inspection technique for such large scale social infrastructures as bridges has been developed with fast neutron.
Non-destructive inspection equipment using terahertz waves is expected to be used in various sectors such as safety and security. The injection-seeded terahertz parametric generator (is-TPG) is suitable for the non-destructive detection of illicit drugs and explosives concealed in mail because of its high power generation and sensitive detectors. This study examined a terahertz spectrometry method suitable for the non-destructive detection of chemicals concealed in mail envelopes. We compared the transmission spectra of three saccharides in different covering materials using is-TPG and terahertz time-domain spectroscopy. In addition, we carried out terahertz spectroscopic imaging on chemicals concealed in thick mail envelopes. As a result, we demonstrated that spectrometry or spectroscopic imaging using is-TPG is effective in detecting chemicals concealed in such items.