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Nanomaterials for Theranostics: Recent Advances and Future Challenges *
Published in Valerio Voliani, Nanomaterials and Neoplasms, 2021
Eun-Kyung Lim, Taekhoon Kim, Soonmyung Paik, Seungjoo Haam, Yong-Min Huh, Kwangyeol Lee
QDs have been extensively studied because of the excellent quantum yield, low photobleaching, sharply defined photoluminescence signals, and robustness under physiological conditions. The optical property of QDs can be easily fine tuned by controlling the size and composition [157, 275–290]. The most advanced band gap engineering has been accomplished with core–shell nanostructures [291]. Although the cytotoxicity of metals such as Cd has not been completely resolved, the advantage of QDs over organic molecules as optical imaging probes is obvious. Encapsulation of QDs in biologically safe matrices such as Si, SiO2, or polymer has been attempted to mitigate the cell toxicity due to leaching of the nanoparticles [144, 145, 292–307]. While the cytotoxicity of QDs needs to be significantly reduced before they can be used in biomedical application, QDs as biological imaging and labeling probes have provided valuable information on important cellular events in live or single cells over long periods because of their high fluorescence quantum yields, narrow emission spectra, broad absorption profiles, and superior photostabililty.
Autofluorescence as a Parameter to Study Pharmaceutical Materials
Published in Victoria Vladimirovna Roshchina, Fluorescence of Living Plant Cells for Phytomedicine Preparations, 2020
Victoria Vladimirovna Roshchina
In many cases, intact secretory cells show multicomponent fluorescence spectra, and it is necessary to know the chemical composition of the studied plant species and the predominant components in order to compare them with the emission of individual components (Roshchina 2008). In this process, there are many limitations. We cannot compare quantum yields of the compounds met in secretory cells, because it is impossible to determine them. Data about the absorption spectra of the intact cells and the secretions are absent. Moreover, the modern concept of quantum yield applies only to solutions of the pure compounds studied. Also, the fluorescence behavior in the mixtures of the compounds is not yet clear.
Reactivities of Amino Acids and Proteins with Iodine
Published in Erwin Regoeczi, Iodine-Labeled Plasma Proteins, 2019
The likely interpretation of the heparin effect referred to above is that on interacting with the mucopolysaccharide, the protein undergoes a marked conformational change. As a corollary to that, some of its six tryptophanyl residues acquire a less polar milieu where collisions are less frequent, thus explaining the enhanced quantum yield. This effect is the opposite one to fluorescence quenching. Different processes may underlie quenching; specific internal quenching can be effected by certain ionizable groups (e.g., carboxyl groups114) as a function of the pH; static quenching117 involves the formation of nonfluorescent complexes of the fluorophore with an agent; collisional quenching is a popular technique for the study of the accessibility and dynamic exposure of tryptophanyl residues in proteins. Iodide,118,119 bromate ,120 and acrylamide (CH2=CHCONH2)121,122 are probes with limited penetrating capability, while molecular oxygen117 can also quench indole fluorophores which are situated in the interior of the protein molecule.
Honeyberry-derived carbon quantum dots ameliorate LPS-induced neuroinflammation and oxidative stress through Nrf2/HO-1 signalling in HMC3 cells
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2023
Sanjay , Anshul Sharma, Hae-Jeung Lee
Fresh honeyberries were cleansed, delicately rinsed in tap water to eliminate any dirt or soil residues, spread out on tissue paper sheets, and allowed to air dry. After that, cleaned honeyberry fruits (200 g) were immersed in 200 ml of double distilled water and ground for 1 min using a high-speed blender at room temperature, then filtered via a filter paper (Toyo Advantec Filter Paper-300 mm). The CQDs from HB extract (filtrate) was synthesized by a hydrothermal approach at 200 °C for 24 h. The solution thus obtained was filtered through a 0.22 μM filter, dialyzed, and lyophilized as reported previously [14,28]. The as-prepared CQDs were characterized using various tools. Quantum yield was measured on the previously established protocol [14,17]. The details have been provided in the supplementary file.
Use of Ag-Au-ICG to increase fluorescence image of human hepatocellular carcinoma cell lines
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2023
Pattarapol Sittisart, Kitsakorn Locharoenrat
ICG in different media (deionised water and 1% Intralipid) was prepared at concentrations of 1.3, 2.5, 5.9, 10.8, 18.4, 24.2, 28.7, and 32.3 μM. We used 1 ml of 20% Intralipid and diluted it in up to 20 ml of saline solution to obtain the 1% Intralipid [20]. ICG solution was made fresh and used within 2 h. Ag-Au was obtained as colloidal solution in different media (deionised water and 1% Intralipid) at concentrations of 47.5, 52.8, 59.4, 67.9, 79.3, 86.5, 91.4, and 93.2 nM. The prepared solution was a 1:1 mix ratio (v/v) to obtain the target concentrations for different reaction times (Table 1). Subsequently, absorbance spectra of Ag-Au-ICG and free ICG were measured at 300–1100 nm using a spectrophotometer (Avantes, Netherlands). Total time for each data acquisition was approximately 30 s. The emission spectra were collected using a 660 nm LED excitation wavelength available for fluorescence experiments. The spectra were obtained within 1 h of dilution preparation. Fluorescence quantum yield was modified as follows [21,22]: QS and Qc are the fluorescence quantum yields of the sample and control, respectively. IS and IC represent the integrated fluorescence intensities of the sample and control, respectively. AS and AC represent the absorbance of the sample and control, respectively.
Updated insight into the characterization of nano-emulsions
Published in Expert Opinion on Drug Delivery, 2023
Xinyue Wang, Halina Anton, Thierry Vandamme, Nicolas Anton
Our group has recently developed a new ACQ-based method for investigating the stability of NE encapsulation [117]. Fluorescent dye NR668 (lipophilic Nile red derivative), insoluble in water, was encapsulated in NEs at a concentration in which ACQ occurred. If the NE content leaks toward an acceptor medium the quantum yield increases, together with an emission shift due to the dye solvatochromism. By changing the acceptor with various proportions of non-labeled NE, it was possible to identify the key parameters responsible for the dye leakage [117]. This study disclosed that molecular release follows a similar mechanism of Ostwald or compositional ripening, in function of the partial solubility of the encapsulated dye in the continuous water phase. In addition, it emphasized that the equilibrium governing the loading of acceptors is not between droplets, but rather between the acceptor droplets and the dyes partially solubilized in the continuous phase [117].