THz Biomed or THz radiation is

THz-Biomed, or THz radiation, is proposed an efficient, label-free, reagent-less and nondestructive detection methods, which is indispensable for laboratory medicine. Studies show that low-frequency internal motions (e.g., skeleton vibration and rotation) and weak bonds (e.g., Hydrogen bond and van der Waals force) of biological molecules have a time scale which corresponds to THz radiation frequency range. Therefore, many biological molecules have specific THz fingerprint. THz spectroscopy has several unique advantages, compared with infrared spectroscopy, X-ray or other traditional spectral analysis techniques. Firstly, with low photon energy, THz wave is nonionizing for biological molecules, cells and tissues. So THz technology is particularly suitable for in vivo nondestructive examination. Secondly, with both imaging and spectroscopy properties, THz waves can detect not only the quantity and function of biomolecules, but also can analyze the composition and structure, which are difficult to be obtained by other electromagnetic bands. Thirdly, different biological molecules have specific THz fingerprint, thus THz radiation can simultaneously reveal the composition information, such as biological macromolecules, within clinical samples in a harmless way, which is indispensable for laboratory medicine. The applications of THz technology in laboratory medicine will focus on the disease imaging diagnosis, label-free DNA sequencing, mechanism and MG262 differences for biological tissue, bacterial rapid detection, interactions between biological samples, and the biosecurity on biological samples and biological processes. It has been reported that crystalline form of fructose and glucose can be identified by THz spectroscopy. And the characteristic THz spectrum fingerprints of several bimoleculars (e.g., peptides, nucleic acids, serum proteins, and collagen) have been gradually found. For bacteria detection, Globus and co-workers obtained the unique THz vibration spectrum fingerprints of bacteria and achieved characterization of different bacteria. Label-free quantification of DNA fragments were achieved by terahertz time-domain spectroscopy (THz-TDS). The detection limit was as low as 0.1nagμL−1 and the minimum sample volume was only 10μl. Besides, it is worth mention that a portable terahertz biomedical detector has been fabricated. Moreover, terahertz detection system was developed for the detection of clinical tumor samples. With the development of these hardware devices, THz technology has great potential in laboratory application.
Surface-enhanced Raman spectroscopy with ultra-sensitive capability and engineered selectivity has become a robust technique to analyze biomolecules Raman scattering is a non-elastic scattering phenomenon, which is produced by wavelength changes of excited molecular. The energy difference between scattered light and excitation wave corresponds to the vibrational level of molecules, which allows Raman spectroscopy to be used for identification of particular chemical group. Surface-enhanced Raman spectroscopy (SERS), also known as surface-enhanced Raman scattering, is a type of vibration spectroscopic technique that enhances Raman scattering by molecules adsorbed on metallic nanostructures (e.g., metal nanoparticles, plasmonic-magnetic silica nanotubes). The Raman signal is largely amplified by roughened metal substrates with an enhancement factor as much as 1010–1011.
SERS has become a promising candidate technique for various biomedical applications, and SERS based platforms are superior to traditional detection methods Firstly, Raman scattering is almost instantaneous, which result in a more stable signal without photodegradation. Secondly, kinds of SERS signal can be excited simultaneously by a single laser beam, which enable multiplexed detection of different targets. Thirdly, SERS signal has almost no water interference, which is particularly suitable for biological imaging. Furthermore, the required sample volume for SERS detection is extremely low and without pretreatment. Extensive efforts have been devoted to the application of SERS for the detection and imaging of bimoleculars (e.g., nucleic acid, protein, and cell). In recent years, noble-metal-free materials have exhibited superior performance, which overcome the shortcomings of noble-metal nanostructures based SERS platform. In 2008, stimulated Raman spectroscopy (SRS) has been developed. The SRS signal intensity has linear relationship with concentration without labeling and signal distortions. SRS has the inherent three-dimensional imaging capabilities, which describe the dynamic process of life activities through quantitative acquisition of images. In 2011, Zhang et al. demonstrated imaging of nucleic acids and proteins in drosophila larvae salivary gland cells and mammalian cells, and real-time imaging of distribution changes of living DNA content was obtained, which contributed to a better understanding of cell development and proliferation process. In recent years, the Raman imaging technology showed potential to distinguish different types of breast cancer cells. SERS was used for the imaging of three kinds of molecules which are closely related to breast cancer. This demonstrated that SERS has potential to be applied for the diagnosis of breast cancer.