Review on near-field detection technology in the biomedical field

We review the recent biomedical detection developments of scanning near-field optical microscopy(SNOM),focusing on scattering-type SNOM,atomic force microscope-based infrared spectroscopy,peak force infrared microscopy,and photo-induced force microscopy,which have the advantages of label-free,noninvasive,and specific spectral recognition.Considering the high water content of biological samples and the strong absorption of water by infrared waves,we divide the relevant research on these techniques into two categories:one based on a nonliquid environment and the other based on a liquid environment.In the nonliquid environment,the chemical composition and structural information of biomedical samples can be obtained with nanometer resolution.In the liquid environment,these techniques can be used to monitor the dynamic chemical reaction process and track the process of chemical composition and structural change of single molecules,which is conducive to exploring the development mechanism of physiological processes.We elaborate their experimental challenges,technical means,and actual cases for three microbiomedical samples(including biomacromolecules,cells,and tissues).We also discuss the prospects and challenges for their development.Our work lays a foundation for the rational design and efficient use of near-field optical microscopy to explore the characteristics of microscopic biology.

Terahertz Spectroscopy for Accurate Identification of Panax quinquefolium Basing on Nonconjugated 24(R)-Pseudoginsenoside F_(11)

Panax quinquefolium is a perennial herbaceous plant that contains many beneficial ginsenosides with diverse pharmacological effects.24(R)-pseudoginsenoside F_(11)is specific to P.quinquefolium,a useful biomarker for distinguishing this species from other related plants.However,because of its nonconjugated property and the complexity of existing detection methods,this biomarker cannot be used as the identification standard.We herein present a stable 24(R)-pseudoginsenoside F_(11)fingerprint spectrum in the terahertz band,thereby proving that F_(11)can be detected and quantitatively analyzed via terahertz spectroscopy.We also analyzed the sample by high-performance liquid chromatography-triple quadrupole mass spectrometry.The difference between the normalized data for the two analytical methods was less than 5%.Furthermore,P.quinquefolium from different areas and other substances can be clearly distinguished based on these terahertz spectra with a standard principal component analysis.Our method is a fast,simple,and cost-effective approach for identifying and quantitatively analyzing P.quinquefolium.