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Gold Nanomaterials at Work in Biomedicine *
Published in Valerio Voliani, Nanomaterials and Neoplasms, 2021
Xuan Yang, Miaoxin Yang, Pang Bo, Madeline Vara, Younan Xia
It was demonstrated that SERS imaging could also be utilized for the monitoring of therapeutic drugs in live cells. With the introduction of a new instrument design, SERS images can be acquired at a high enough speed to enable the real-time tracking of Au nanoparticles in live cells [514–518]. In 2008, Kawata and coworkers developed the slit-scanning Raman microscope for imaging live cells [514]. Using the same technique, they also investigated the endocytosis process of 50 nm Au nanoparticles by macrophage and tracked the movement of particles with high spatial and temporal resolutions [497, 519]. When illuminated with a 785 nm laser in a continuous wave (CW) mode at a power density of 15 mW/µm2, SERS signals with reasonable SNR could be obtained within the first 2.5 min. After incubation for 30 min, they observed that the Au nanoparticles attached to the cell surface had begun to enter the cell. The Au nanoparticles can also be conjugated with functional groups to serve as molecular probes. To this end, Kneipp and coworkers explored the use of aggregates assembled from p-MBA-coated Au nanoparticles for pH sensing over a broad range [520]. As shown in Fig. 5.36B, the local pH value could be readily derived from the ratio of peak intensities for the 1423 and 1076 cm−1 bands of p-MBA.
Fluorescent Analysis Technique
Published in Victoria Vladimirovna Roshchina, Fluorescence of Living Plant Cells for Phytomedicine Preparations, 2020
Victoria Vladimirovna Roshchina
The use of Raman spectroscopy in microscopy enables label-free and chemically selective imaging, which has become important in recent years. Molecular identification originates from the specific frequencies of molecular vibrations appearing in a Raman spectrum. A drawback is that spontaneous Raman scattering is a very weak optical effect compared with fluorescence or elastic light scattering. Approximately only one or fewer of 106 photons of scattered light undergoes an energy loss or gain, so-called Stokes and anti-Stokes Raman scattering, through interaction with the molecular vibrations. The imaging of a typical biological sample with Raman microscopy is not always suitable, because it requires very long image acquisition times, even when intense laser beams are used.
Molecular Vibrational Imaging by Coherent Raman Scattering
Published in Shoogo Ueno, Bioimaging, 2020
Yasuyuki Ozeki, Hideaki Kano, Naoki Fukutake
Recently, the interest toward Raman imaging has been increasing, where Raman scattering from a large number of locations was successively measured to obtain the vibrational spectroscopic information at every image pixel; however, the applications of Raman imaging are limited by its long acquisition time. Typically, the detection of spontaneous Raman scattering requires one second for each pixel and several tens of minutes for an image because the intensity of Raman scattering is relatively low. Furthermore, spontaneous Raman scattering is easily overwhelmed by the fluorescence of biological samples, as well as of optics or cover slips. Therefore, spontaneous Raman microscopy requires special attention in instrumentation, sample preparation, measurement, and data analysis.
Application of three-dimensional Raman imaging to determination of the relationship between cellular localization of diesel exhaust particles and the toxicity
Published in Toxicology Mechanisms and Methods, 2022
Langying Ou, Akiko Honda, Natsuko Miyasaka, Sakiko Akaji, Issei Omori, Raga Ishikawa, Yinpeng Li, Kayo Ueda, Hirohisa Takano
Cells on the slides after microscopic detection were fixed in 4% paraformaldehyde and then gently washed with pure water. Raman detection, a technology based on the use of a laser for chemical characterization of samples, was performed to evaluate the fixed cells using a LabRAM HR Evolution Raman microscope (Horiba, Ltd., Kyoto, Japan) at a laser excitation wavelength of 532 nm and a groove density of 300 g/mm for grating. Labspec6 software (HORIBA) was used for the pre-processing and analysis of Raman spectral data. 3D Raman image was visualized by collecting data on 0.5 μm (x-direction), 0.5 μm (y-direction), 1 μm (z-direction) increment spanning the cell volume with a spectral range from 200 to 3100 cm−1, then the data was treated by classical least-squares (CLS) model.
Graphene-based materials do not impair physiology, gene expression and growth dynamics of the aeroterrestrial microalga Trebouxia gelatinosa
Published in Nanotoxicology, 2019
Elisa Banchi, Fabio Candotto Carniel, Alice Montagner, Susanna Bosi, Mattia Bramini, Matteo Crosera, Verónica León, Cristina Martín, Alberto Pallavicini, Ester Vázquez, Maurizio Prato, Mauro Tretiach
Raman spectroscopy: A sub-aliquot (10 μL) of algal suspensions prepared as above was vacuum filtered on a CA membrane (10 µm pore size), and the algae were gently washed with 50 mL of distilled water to remove the floating GBMs. Algal cells were then immediately resuspended with 500 µL of distilled water, and three drops of 40 µL each were poured on PolysineTM Microscope Adhesion Slides (Thermo Fisher Scientific, USA), which were put into a 50 mL Falcon tube and immediately frozen in liquid N2, and freeze-dried for 24 h. Raman spectra were recorded with an inVia Raman Microscope (Renishaw, UK) equipped with a 532 nm point-based laser. At first, confocal mode was used to collect Raman spectra at defined x,y coordinates and at different depths within the samples. However, during the acquisition of a series of spectra at the same coordinates, cells were progressively destroyed by the laser. To overcome this, samples were measured with a fixed exposure time of 1 s using the objective 50×, 10 accumulations and three different laser power densities (0.6, 3 and 6 mW µm−2) to penetrate at different levels into the cell.
Co-delivery of an HIV prophylactic and contraceptive using PGSU as a long-acting multipurpose prevention technology
Published in Expert Opinion on Drug Delivery, 2023
Jarrod Cohen, Dennis Shull, Stephanie Reed
Additionally, it is important to understand content uniformity across a single device. Due to the insoluble nature of crosslinked elastomers, common extraction techniques across a device can be challenging. Additionally, opacity of drug-loaded devices can introduce challenges for certain microscopy and spectroscopy methods. One solution that has shown promise is Raman microscopy. Using API standards, heat maps can be generated across a given sample length or volume to spatially identify API-rich or API-poor regions in the dosage form (Figure 4a). This method is also nondestructive, making it ideal to perform quality control testings such as in a process analytical technique (PAT) prior to lot release and subsequent dissolution studies.