Truly Multicolor Emissive Hyperbranched Polysiloxane: Synthesis, Mechanism Study, and Visualization of Controlled Drug Release

Abstract

Unconventional fluorescent polymers have attracted increasing attention due to their facile synthesis, excellent biocompatibility, and novel photophysical properties. In this work, a truly multicolor emissive hyperbranched polysiloxane (HBPSi-β-CD) is obtained through adjusting the distribution of electron-rich atoms and grafting β-cyclodextrin; the quantum yields of HBPSi-β-CD after being excited by 360, 420, 450, and 550 nm are 19.36, 31.46, 46.14 and 44.84%, respectively. The density functional theory calculations reveal that the truly multicolor emission is derived from the formed electron delocalization among the hydroxyl, amine, ether, and −Si­(O)3 groups due to the strong intermolecular interaction, high density of electron-rich atoms, and low steric hindrance among functional groups. The prepared polymers could serve as a multisensitivity sensor in detecting Fe3+, Cu2+, and Co2+. The HBPSi-β-CD shows low cytotoxicity and excellent cellular imaging capability. The self-assembly of HBPSi-β-CD also possesses high drug loading capacity and pH-controlled drug release, especially, the drug delivery system could be applied in the visualization of controlled drug delivery.

High-Efficiency Long-Wavelength Fluorescent Hyperbranched Polysiloxanes: Synthesis, Emission Mechanism, Information Encryption, and Film Preparation

“…Yan et al found that the electron cloud of carbonyl and CC bonds in polysiloxane will overlap and form multiple through-space conjugation rings, and blue, green, and red light will be generated under different excitations; hence, the emission mechanism named multiring-induced multicolor emission is proposed . We found that the electronic communication between electron-rich functional groups could be promoted through decreasing the distance and steric hindrance and then generate large spatial electronic delocalizations, and finally, bright blue, green, yellow, and red emissions are observed . These research studies show that the long-wavelength emission of polymers is closely related to the species of functional groups, density of electron-rich atoms, interactions between functional groups, morphologies of aggregates, and so on.…”

“…UV–vis absorbance was first studied to confirm the presence of heterogeneous special electronic delocalizations in the aggregates of polymers. In the UV–vis absorbance spectra of HBPSi (Figure a), a peak at 208 is observed, which is caused by the n−σ* electronic transitions of hydroxyl, −Si­(O) 3 , and amine groups. , Different with the UV–vis absorbance spectra of HBPSi, new absorbance peaks at about 269, 340, 400, 450, and 500 nm in the UV–vis absorbance spectra of HBPSi-Phe (Figure b), HBPSi-Tyr (Figure c), and HBPSi-Trp (Figure d) are also observed at concentrated solutions, and these new peaks are enhanced with increasing concentrations. The absorbance at 269 nm might come from the π–π* electronic transitions of the conjugated π bonds in the amino acids (Figure S3).…”

“…The absorbance at 269 nm might come from the π–π* electronic transitions of the conjugated π bonds in the amino acids (Figure S3). Moreover, the long-wavelength absorptions at 340, 400, 450, and 500 nm come from the large spatial electronic delocalizations. , With increasing the concentration, HBPSi-Phe, HBPSi-Tyr, and HBPSi-Trp gradually aggregate, and then, the conjugated π bonds and electron-rich functional groups are clustered, and the electronic communication is enhanced, forming large spatial electronic delocalizations. Larger spatial electronic delocalizations could generate longer wavelength emissions. − Thus, HBPSi-Phe, HBPSi-Tyr, and HBPSi-Trp might emit long-wavelength emissions.…”

Nonconventional Fluorescent Hyperbranched Polymer Dots as Skin Nanocarriers Constructed from an Olefinic Aliphatic AB2-Type Monomer

“…23−26 Yan et al synthesized a multicolor emissive hyperbranched polysiloxane (HBPSi) that they applied to detect metal ions and use as a nanocarrier; it exhibited multicolor fluorescence because of CIE and its cluster size. 27 Interestingly, Yang et al used thiolactone chemistry to synthesize aliphatic polyamides (PAs) that could produce strong fluorescence as a result of polymerization-induced emissions (PIEs); 28 these aliphatic PAs were applied to organelle-specific imaging.…”

“…The nonconventional fluorescence observed with nonconjugated moieties can lead to strong fluorescence emissions with excellent photostability because of resistance to photobleaching and nonquenching effects. , Furthermore, nonconjugated HBP nanomaterials featuring multiple hydrogen-bonding interactions can have chemical structures similar to those of biopolymers, with excellent water solubility, chain flexibility, and structural tunability as well as the potential for facile one-pot preparation, environmental friendliness, and use in biological fluorescence imaging. − Nonconventional fluorescent polymers have been applied in various applications, including the detection of metal ions, bioimaging, and nanodrug formulation. − Yan et al synthesized a multicolor emissive hyperbranched polysiloxane (HBPSi) that they applied to detect metal ions and use as a nanocarrier; it exhibited multicolor fluorescence because of CIE and its cluster size . Interestingly, Yang et al used thiolactone chemistry to synthesize aliphatic polyamides (PAs) that could produce strong fluorescence as a result of polymerization-induced emissions (PIEs); these aliphatic PAs were applied to organelle-specific imaging.…”