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Fluorescent Quantum Dots for Biomedical Applications
Published in Vladimir Torchilin, Mansoor M Amiji, Handbook of Materials for Nanomedicine, 2011
Kelly Kenniff, Keith Payton, Swadeshmukul Santra
The first but simplest approach is the “cap exchange” with bifunctional molecules. A typical bifunctional molecule presents a surface-anchoring moiety to bind to the hydrophobic inorganic Qdot surface (for example, thiol) and an opposing hydrophilic end group (for example, hydroxyl or carboxyl) to achieve water-dispersibility. These include an array of thiol and phosphine mono and multidentate ligands.8,16,57–59 The compact monomercapto ligands although simple to synthesize, have short shelf lives (less than one week) due to dynamic thiol-ZnS interactions.60 Substitution from mono to dithiol dihydrolipoic acid ligands improves the long-term stability from 1 week to 1 to 2 years, suggesting that polydentate thiolated ligands could be even more effective.16,58,60
Activatable Fluorescent Quantum Dots
Published in Vladimir Torchilin, Handbook of Materials for Nanomedicine, 2020
Tyler Maxwell, Ziyang Huang, Stephen Smith, Morgan Schaff, Swadeshmukul Santra
Dendrimers have also been used in the fabrication of activatable Qdot probes. Nocera et al. coupled poly(amido amine) (PAMAM) dendrimers to CdSe/ZnS Qdots though EDC cross-linking to the carboxyl group of dihydrolipoic acid (dithiol biomolecule) [36]. The abundance of amine groups of the dendrimer allowed for the coupling of 26 acceptor dyes (SNARF-5F) to each Qdot. The sensor was sensitive to pH values ranging from 6.0–8.0 with increased SNARF emission at higher pH due to better FRET overlap. The sensitivity of the probe was assessed in the presence of bovine serum albumin (BSA) and it was found that the SNARF emission intensity decreased due to hydrophobic interactions with the BSA.
Overview of the application of inorganic nanomaterials in breast cancer diagnosis
Published in Inorganic and Nano-Metal Chemistry, 2022
Asghar Ashrafi Hafez, Ahmad Salimi, Zhaleh Jamali, Mohammad Shabani, Hiva Sheikhghaderi
Due to the existence of a highlight challenge regarding QDs water solubility, so there is a remarkable necessity for overcoming such this obstacle via some modification approaches. By addressing this reason, various strategies were applied to achieve this aim as one approach can demonstrate to ligand the exchange of the original hydrophobic surfactant ligands by hydrophilic molecules.[132] For this purpose, a variety of thiol-containing compound molecules were applied such as sophisticated compounds (e.g., alkylthiol terminated DNA),[140] mercaptoacetic acid,[141] D,L-cysteine[142] and poly(ethylene glycol [PEG])-terminated dihydrolipoic acid.[143] In the same fashion, for both rising water solubility and improving biocompatibility aspects it could be encapsulated into a layer of phospholipid micelles, amphiphilic polysaccharides, polymer shells, oligomeric phosphine coating and amphiphilic diblock or triblock copolymers.[132] Consequently, CdTe QDs were synthesized successfully by glutathione as the capping agent and used for cell-imaging purposes, in which quantum yield in this system was up to 50% with fluorescence emissions tunable between 360 and 700 nm.[144]
The individual and combined effects of spaceflight radiation and microgravity on biologic systems and functional outcomes
Published in Journal of Environmental Science and Health, Part C, 2021
Jeffrey S. Willey, Richard A. Britten, Elizabeth Blaber, Candice G.T. Tahimic, Jeffrey Chancellor, Marie Mortreux, Larry D. Sanford, Angela J. Kubik, Michael D. Delp, Xiao Wen Mao
Countermeasures in place to prevent osteopenia during ISS missions include load-bearing exercises. Strides also have been made in identifying other promising candidate countermeasures for mitigating spaceflight-induced bone loss. Antioxidants are often considered as candidate countermeasures to protect against radiation and/or HLU-induced bone loss: as previously noted altered NO concentration (and expanded upon in Section 5; Cardiovascular Response) is associated with radiation and HLU,83 and biomarkers for oxidative stress in the marrow in another study has been identified to increase after radiation but not HLU,78 highlighting some inconsistencies in the literature. In a rodent model, pre-feeding with an antioxidant-rich dietary supplement (dried plum) prevented bone loss and decrements in bone strength resulting from HLU, ionizing radiation and in combination.94 These results suggest some shared mechanisms underlying microgravity and radiation-induced bone loss. However, while antioxidants such as dihydrolipoic acid (DHLA) or an antioxidant cocktail have been shown to be less efficacious at reducing bone loss in mice early after 2 Gy gamma ray exposure, 97 alpha-lipoic acid 78 has been shown to reduce early bone loss after 2 Gy gamma rays. Collectively, these findings suggest that antioxidants have varying efficacies in preventing the negative effects of spaceflight stressors on bone. Future studies are needed to better understand the underlying mechanisms for the protective effects of promising antioxidant-based countermeasures for spaceflight.