Fluorescent Technology in the Assessment of Metabolic Disorders in Diabetes
Andrey V. Dunaev, Valery V. Tuchin in Biomedical Photonics for Diabetes Research, 2023
Noninvasive optical methods are increasingly used in biomedical diagnostics. Fluorescence spectroscopy, in particular, has found its application in chemistry, biology, and various fields of medicine. This method is highly sensitive and allows us to study various pathological changes of biological tissues in the development of socially significant diseases. Fluorescence spectroscopy and imaging techniques are probably the most common biomedical photonics methods used in skin research. By analyzing fluorescence data, one can extract information about the structure and component composition of the biological tissue and its functional state. Fluorescence provides insight into both the conformation of fluorescent molecules and their binding as well as their interactions within biological tissues.
Radiometry
Michael Ljungberg in Handbook of Nuclear Medicine and Molecular Imaging for Physicists, 2022
Luminescence is thus due to the de-excitation of the π-electrons and the process can be divided into three kinds, which differ regarding the timescale between excitation and de-excitation. These three kinds of luminescence are called fluorescence, phosphorescence, and delayed fluorescence. The total spin angular momentum of the excited molecule can either be 0 or 1 and, hence, two separate systems of energy levels are available for the excited molecule: singlet states and triplet states (Figure 5.1). If the molecule absorbs energy from a charged particle traversing the detector material (e.g. an electron liberated by photoelectric absorption or Compton scattering), it may be excited into one of the states depicted in Figure. 5.1. However, within the order of picoseconds, electrons excited to the higher energy states will eventually de-excite to the state S1,0 by non-radiative transitions. Fluorescence then occurs in the transition from S1,0 or T1,0 to S0,0 and is characterized by prompt (on the order of nanoseconds) emission of light, the intensity of which decays exponentially with time.
Conjugation and Other Methods in Polymeric Vaccines
Mesut Karahan in Synthetic Peptide Vaccine Models, 2021
Fluorescence life is the time the induced level molecule passes, before it passes the basic electronic level. Most aromatic molecules have a fluorescence lifetime of 10 ns. The maximum wavelengths that aromatic amino acids absorb and fluorescence will depend on the fluorescent lifetime. In the studies, the synthesis of peptide epitopes is carried out in the structure of tryptophan and other aromatic amino acids, especially in foot and mouth disease, hepatitis B, and other diseases (Budama 2006). On synthetic polyelectrolytes and their structures (Budama et al. 2008), using different wavelengths is determined by the degree of peptide-polymer conjugation reaction using biomolecules (peptide, protein, etc.) with the same type of electric charge and, lastly, the FRET method is used to investigate the metal binding mechanism of the biopolymer (Acar et al. 2019; Karahan, Mustafaeva, and Ozer 2007). With the help of the FRET method, the intermolecular distance relationships can be examined in the distance measurement between the two places in the macromolecules (Acar et al. 2019). In addition, this method is considered to be a powerful technique to study molecular interactions in living cells with improved spatial (angstrom) and temporal (nanosecond) resolution, distance range, and sensitivity, and a wider range of biological applications (Sekar and Periasamy 2003; Carmona, Juliano, and Juliano 2009). Investigation of protein fragments in terms of these properties is thought to be of great benefit in peptide vaccine synthesis.
Bacterial outer membrane vesicles-cloaked modified zein nanoparticles for oral delivery of paclitaxel
Published in Pharmaceutical Development and Technology, 2023
Zeyu Wang, Yuqi Chu, Xu Tao, Jianchao Li, Lihong Wang, Yuli Sang, Xiuli Lu, Lijiang Chen
ZN's surface charge characteristics make it easier for it to interact with other molecules and encourage the formation of complexes (Giteru et al. 2021). Molecular interactions between zein and drugs assume great significance for drug design and development as they affect various aspects such as carrier morphology, drug payload, and release behavior (Wang et al. 2018). Additionally, understanding reactions and interactions between proteins and drugs can also shed light on how zein loads PTX, providing the theoretical basis for their development. Fluorescence quenching is the phenomenon by which small molecules of medicines are added to proteins with endogenous fluorescence to reduce the intensity of the protein fluorescence (Lakowicz 2006). As pointed out in Figure 1(A), zein had an emission peak at 307 nm, mainly attributed to the fluorescent emission of a tyrosine residue. Zein’s fluorescence intensity significantly decreased with an increase in PTX concentration, but its distinctive absorption peak type remained unchanged. The typical fluorescence quenching phenomenon indicated the interaction between zein and PTX.
Quantitative autofluorescence: Review of Current Technical Aspects and Applications in Chorioretinal Disease
Published in Seminars in Ophthalmology, 2021
Iris Deitch, Kevin Ferenchak, John B. Miller
Quantitative FAF (qAF) measures and compares AF intensities over time. It is a novel developing technology that is not yet part of routine clinical care, but may aid in diagnosis and longitudinal disease monitoring. It incorporates a standard fluorescent reference into the imaging device while considering factors such as laser power, correction of refractive errors and variations.3,4 By incorporating a standard for quantitative comparisons of AF intensities, qAF can help in the understanding of the genotype–phenotype correlations, and offer a potential diagnostic and prognostic tool.1,4,5 Fluorescence lifetime imaging quantifies how long a fluorophore remains in its higher energy state before returning to its ground state. The fluorescence lifetime is specific to individual fluorophores and depends on the metabolic environment. Unlike regular fundus autofluorescence (FAF), in which lipofuscin provides most of the signal, fluorescence lifetime imaging ophthalmoscopy (FLIO) gives additional information about fluorophores with weaker FAF intensities, such as macular pigment and the photoreceptor layer.
A mechanistic review on the dissolution phase behavior and supersaturation stabilization of amorphous solid dispersions
Published in Drug Development and Industrial Pharmacy, 2021
P. Ashwathy, Akshaya T. Anto, M. S. Sudheesh
A variety of methods have been used to analyze phase behavior during LLPS. NMR spectroscopy has been used as a method to determine LLPS by characterizing the broad peak obtained due to molecular proximity during nanoaggregate formation [28]. The peak intensity is mainly determined by the concentration of drug in the dispersed molecular phase. When the colloidal phase is generated during LLPS, peak intensity remains constant on further increase in drug concentration. UV extinction coefficient method is an easy method to observe LLPS [32,40]. The wavelength at which the drug molecule shows no absorbance is selected. A sudden change in the extinction coefficient represents light scattering due to phase separation. LLPS has also been studied using steady-state fluorescence spectroscopy, by monitoring change in fluorescent intensity and wavelength maxima of an environment-sensitive fluorophore when it partitions into a colloidal rich phase during LLPS [29,40,48]. Fluorescence lifetime is an intrinsic property of a fluorophore, which has also been used to study LLPS [48]. It is the time during which a fluorophore remains in an excited state before returning to the ground state by emitting photons. The advantage of fluorescence lifetime is that it is largely independent of the method of measurement (e.g. wavelength of excitation and duration of exposure) and on the intensity and concentration of the fluorophore (under certain constraints).
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