Facile Preparation of Fluorescent Nanoparticles with Tunable Exciplex Emission and Their Application to Targeted Cellular Imaging

Abstract

Fluorescent nanoparticles with a tunable emission show a good potential for usage in biological imaging. Exciplex emission usually appears with a large red shift from the normal emission peak. The integration of exciplex emission into nanoparticles offers a rational strategy to designing fluorescent nanoparticles with a tunable emission. In this work, we doped electron acceptors into the electron donor poly­(N-vinylcarbazole) (PVK) to develop novel fluorescent nanoparticles with a conveniently modulated PVK emission. Through careful design of the molecular structures of the electron acceptors, we demonstrated that controlled donor–acceptor spatial stacking and electron transitions could regulate the exciplex emission of the PVK/acceptor nanoparticles. Thus, the structurally controlled exciplex formation allowed for the preparation of multicolored fluorescent nanoparticles. Moreover, further modifications with the cyclic peptide RGD showed little disruption to the structure of the PVK/acceptor nanoparticles and the corresponding exciplex emission. Hence, the nanoparticles showed the ability to be used for targeted cellular imaging. On the basis of the RGD-integrin αvβ3 (ligand–receptor) interaction, the nanoparticles were effectively endocytosed by target cancer cells. We anticipate that this research could provide a new strategy for the fabrication of fluorescent nanoparticles with a tunable emission, leading to useful materials for fluorescent imaging.

Controllable Targeted Accumulation of Fluorescent Conjugated Polymers on Bacteria Mediated by a Saccharide Bridge

“…After the solution on the slices naturally dried, the bacteria were fixed with 0.1% glutaraldehyde overnight. Then, the specimens were dehydrated with a series of ethanol (20,30,40,50,60,80,90, and 100%, for 15 min each). The specimens were air-dried and platinum-coated for the SEM measurements.…”

Fluorescent Platforms Based on Organic Molecules for Chemical and Biological Detection

“…These exciplex nanoparticles had a long lifetime of 321 ns, making them good candidates for cell imaging. Furthermore, our group has controlled exciplex formation and corresponding exciplex emission in nanoparticles by careful design and fine tuning of the electron acceptor molecular structure . As shown in Figure a, we synthesized three electron acceptors TPOTZ, BPOTZ, and BPOTZ‐OR with electron‐withdrawing groups, which we then doped into the electron donor poly( N ‐vinylcarbazole) to tune the exciplex formation.…”

“…d) Cell imaging of the exciplex nanoparticles. Reproduced with permission . Copyright 2018, American Chemical Society.…”

Different Surface Interactions between Fluorescent Conjugated Polymers and Biological Targets

“…As the outer surfaces of cells bear recognition molecules, the ligand functionalities modified on CPs can act as mediators for CPs’ selective binding via ligand–receptor recognition. As shown in Figure c, the ligand–receptor recognition is a noncovalent and complex interaction, including antigen–antibody, biotin–avidin, peptide RGD–integrin, lectin–saccharide, folic acid–receptors, and so on. − After CPs are coprecipitated with poly­(styreneco-maleic anhydride) (PSMA) forming nanoparticles, surficial carboxyl groups originated from PSMA can be conjugated with antibody through a classical amidation reaction . Selective cell imaging is achieved on the basis of specific antigen–antibody interaction.…”