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Theranostics: A New Holistic Approach in Nanomedicine
Published in D. Sakthi Kumar, Aswathy Ravindran Girija, Bionanotechnology in Cancer, 2023
Ankit Rochani, Sreejith Raveendran
Molecules like DOX and curcumin tend to fluoresce and can be visualized in the cellular system using confocal microscopy, and they are also an important anticancer molecule. DOX has been explored by developing various hybrid (Fe or AuNPs) or non-hybrid polymeric NPs systems with synthetic and natural polymers for targeted and untargeted anticancer theranostic applications [35]. One such simple design is anti-nucleolin (AS1411)-targeted DOX-loaded PLGA NPs for theranostic application. This was tested and proven effective against the C26 (colon) cancer cell line under in vitro and in vivo conditions (as shown in Figure 14.2) [36]. In recent past, it was shown that transferrin (Tf)-templated copper nanocluster (Tf-Cu) was also synthesized and formulated into spherical Tf-Cu DOX NPs due to electrostatic interaction between DOX and Tf-Cu. It acts as a theranostic system when analyzed using the FRET imaging technique [37]. Like DOX, curcumin is also extensively explored for its theranostic potential in the form of polymeric (PLGA, MPEG-PCL, ß-cyclodextrin, poly(butyl cyanoacrylate, polyethylene glycol (PEG)-cholesterol, and others) NP systems [9]. Curcumin is a generic material that has been extensively explored for its use in various infectious and non-infectious diseases. This natural molecule has been considered a model system in developing various types of interesting TNP designs by combining different types of metallic or organic drug molecules.
Molecular Imaging of Viable Cancer Cells
Published in Shoogo Ueno, Bioimaging, 2020
Förster resonance energy transfer (FRET) is energy transfer from the excited state of the fluorophore (donor) to an adjacent molecule (acceptor). In order to design FRET-based probes, it is important to select a fluorophore or chromophore pair so that the donor emission spectrum overlaps well with the acceptor absorbance spectrum. Since the energy transfer takes place only when donor and acceptor are in close vicinity to each other, most FRET-based probes are designed so that the distance between the two fluorophores changes before and after reaction with the target molecule. Combinations of fluorophore (donor) and quencher (acceptor) are used in the design of activatable probes targeted to cancer-related enzymes.
Noninvasive glucose monitoring
Published in Moshe Hod, Lois G. Jovanovic, Gian Carlo Di Renzo, Alberto de Leiva, Oded Langer, Textbook of Diabetes and Pregnancy, 2018
A different technology is fluorescence resonance energy transfer (FRET). First studied46 in 1988, this technique is based on the transfer of energy from donor molecules to acceptor molecules, thereby decreasing fluorescence levels allowing for miniscule changes in the level of molecules to be detected. Studied in preclinical models,47 generally a contact lens is used and boronic acid is usually the donor molecule. A few devices have been patented, but many problems still need to be addressed—the longer time it takes for tear collection, the more the need for an external light source and the lack of a predictable relationship between blood and tear glucose levels.
Discovery of RNA-targeted small molecules through the merging of experimental and computational technologies
Published in Expert Opinion on Drug Discovery, 2023
The three fluorescence-based assays that are often employed for screening of RNA binders are: (1) fluorescence resonance energy transfer (FRET)-based assay (Figure 3(a)), (2) time-resolved FRET (TR-FRET) assay, and fluorescent indicator displacement (FID). FRET refers to the transfer of energy from a donor fluorophore to an acceptor fluorophore conjugated to the target biomolecule. FRET-based assays are convenient and extremely sensitive and have become popular for screening small-molecule libraries against RNA targets. Simone et al. [92] used a FRET-based assay to screen for small-molecule stabilizers of the C9orf72 (G4C2)4 G-quadruplex RNA, which is a known cause of frontotemporal dementia and amyotrophic lateral sclerosis [116]. The authors monitored the changes in melting temperature of the 5’-FAM and 3’-TAMRA labeled (G4C2)4 RNA upon heating in the presence of small molecules and identified three structurally similar small molecules that stabilize the RNA. The small molecules were subsequently shown to reduce the frequency of RNA foci and the levels of dipeptide repeat protein in C9orf72 patient neurons. Furthermore, the most effective small molecule, DB1273, was found to improve survival and reduce levels of toxic poly-(glycine-arginine) in C9orf72 flies.
A combined “eat me/don’t eat me” strategy based on extracellular vesicles for anticancer nanomedicine
Published in Journal of Extracellular Vesicles, 2020
Zakia Belhadj, Bing He, Hailiang Deng, Siyang Song, Hua Zhang, Xueqing Wang, Wenbing Dai, Qiang Zhang
Lipid vesicles-exosomes fusion was monitored by FRET-based lipid exchange assay as described previously [44]. The FRET acceptor dye (DiI) and donor dye (DiO) were physically encapsulated into the lipid vesicles. A549 cells were then incubated with c(RGDm7)-LS and hybrid c(RGDm7)-LS for 4 h at 37°C. FRET images were visualized with a confocal laser scanning microscope (CLSM, TCS SP5, Leica, Germany). The FRET efficiency is defined as a difference of fluorescence intensity of the donor before and after photobleaching. The FRET efficiency is measured using this equation: FRETeff = (Dpost-Dpre)/Dpost, where Dpost and Dpre correspond to the fluorescence intensity of DiO after and before photobleaching, respectively. FRET occurs at DiO excitation wavelength (484 nm) and DiI emission wavelength (555–655 nm) [45].
Using bispecific antibodies in forced degradation studies to analyze the structure–function relationships of symmetrically and asymmetrically modified antibodies
Published in mAbs, 2019
Adam R. Evans, Michael T. Capaldi, Geetha Goparaju, David Colter, Frank F. Shi, Sarah Aubert, Lian-Chao Li, Jingjie Mo, Michael J. Lewis, Ping Hu, Pedro Alfonso, Promod Mehndiratta
Characterization of the binding of the Fc region of BsAb variants to Fc receptors FcγRI, FcγRIIa, FcγRIIIa, and FcRn was assessed by using a competitive TR-FRET assay. In these methods, binding was assessed by the ability of unlabeled BsAb to compete with a fixed concentration of europium-labeled antibody for binding to the relevant Cy5-labeled Fc receptor. Briefly, FcγRII, FcγRIIIa or FcRn receptor was added to varying concentrations of unlabeled BsAb sample and incubated at room temperature for 90 min in the dark. Following incubation, TR-FRET was measured using a spectrophotometer plate reader (Perkin Elmer, Victor3) with an excitation/emission wavelength of 615 nm and 665 nm. The relative binding activity was then calculated from the mean EC50 value of replicate dose-response curves generated with BsAb and expressed as a percentage of the mean EC50 value of dose-response curves generated with reference material. All TR-FRET binding methods have been validated in accordance with the International Council on Harmonization guidelines.