Monodisperse and Water-Soluble Quantum Dots for SWIR Imaging via Carboxylic Acid Copolymer Ligands

Abstract

Compared to the visible and near-infrared, the short-wave infrared region (SWIR; 1000–2000 nm) has excellent properties for in vivo imaging: low autofluorescence, reduced scattering, and a low-absorption cross-section of blood or tissue. However, the general adoption of SWIR imaging in biomedical research will be enhanced by a broader availability of versatile and bright contrast materials. Quantum dots (QDs) are bright and compact SWIR emitters with narrow size distributions and emission spectra, but their use is limited by the shortcomings of established ligand systems for SWIR QDs. Established ligands often result in SWIR probes with either limited colloidal stability, large size, or broad size distribution or a combination of all three. We present a polymeric QD ligand designed to be compatible with oleate-coated QDs. Our polymeric acid ligand is a copolymer bearing carboxylic acid anchoring groups and PEG-550 chains to solubilize the QD-ligand construct. After a mild and rapid ligand exchange, the resulting constructs are compact (<11 nm hydrodynamic diameter) and have narrow size distribution. Both qualities are preserved for several months in isotonic saline. The constructs are bright in vivo, and to demonstrate their suitability for imaging, we perform whole-body imaging and lymphatic imaging, including visualization of lymphatic flow.

Nanoengineering with RAFT polymers: from nanocomposite design to applications

“…One way of circumventing this issue is to use macromolecular ligands, which can be easily prepared via RAFT polymerization. Here, a multiply-binding copolymer design has been proven to be very effective: one type of monomer contains an anchoring group for QD binding, such as thiol, 164 carboxyl, 146,147 imidazole 112,188,189 and 8-hydroxyquinoline 241 moieties. Another part of the polymer adjusts dispersibility and provides additional properties.…”

“…Again, RAFT polymerization provides a very straightforward synthesis of functional polymers containing PEG derivatives with suitable anchoring groups for diverse nanomaterials. 111,146,181,188,189,238 Zwitterionic polymers possess equal cationic and anionic moieties on the chain: the polymer maintains charge neutrality while carrying high ion density. This unique property makes them highly resistant to nonspecific protein adsorption due to their strong hydration ability resulting from the high charge density.…”

Carbon Dot Therapeutic Platforms: Administration, Distribution, Metabolism, Excretion, Toxicity, and Therapeutic Potential

“…[16] 9) They possess high and stable monodispersity. [17,18] 10) They can be tuned to act as an antioxidant or pro-oxidant depending on final intended use. [19,20] 11) Can be synthesized to be highly hydrophilic or hydrophobic.…”

Hitchhiking Nanoparticles: Mesenchymal Stem Cell-Mediated Delivery of Theranostic Nanoparticles

“…Quantum dots (QDs) are semiconductor nanoparticles with exceptional optical characteristics, ultrasmall size, and a high surface area to volume ratio. These properties make QDs appealing for applications in optoelectronics (e.g., for light emitting diodes and display applications 6,7 ) and biomedicine (e.g., bioimaging, 8,9 cancer targeting and therapy, 10,11 and biosensing 12 ); they are superior to traditionally used dyes due to their brightness and longer fluorescence (FL) lifetime, photostability, high two-photon absorption cross-section, and uncomplicated functionalization with biologically active molecules, which allows selective targeting to certain tissues. 13 QDs can also serve as energy donorsa characteristic, which can be exploited in PDT.…”