Biodegradable Fluorescent SiO₂@MnO₂-Based Sequence Strategy for Glutathione Sensing in a Biological System and Synergistic Theragnostics to Cancer Cells

Abstract

Herein, we report an activatable multifunctional nanocomposite (denoted as FSMP) for glutathione (GSH) sensing and synergistic theragnostics to cancer cells. This novel core–shell architecture orderly consists of a fluorescein isothiocyanate-doped SiO2 core, a methylene blue (MB)-encapsulated porous MnO2 shell, and poly­(ethylene glycol) for shielding the MB from premature leaking. The fluorescence of the core will be effectively quenched by MnO2 due to the Förster resonance energy transfer, and the quenched signals could be recovered in the presence of GSH, as a result of the reduction of MnO2 to Mn2+. The constructed GSH sensing nanoplatform shows stable response to GSH in a linear range of 10–300 μM with the limit of detection of 2.1 μM. Besides acting as a fluorescence quencher and a GSH recognizer, MnO2 also serves as a sequence self-reinforcing Fenton nanoagent based on the GSH sensing to form Mn2+, which exerts the activity to generate •OH from H2O2. Further, combined with the MB-mediated photodynamic 1O2 generation, the multifunctional nanocomposite jointly produces an enhanced therapeutic effect. In addition, FSMP will be degraded within 48 h, thus significantly reducing the potential nanotoxicity. We believe the MnO2-nanomaterial-based sequence strategy could potentially improve biochemical analysis and cancer cell theragnostics applications.

MnOx In Situ Growth-Induced Luminescence and Oxidase-Like Feature Bimodulation of CePO4:Tb Nanorods: Toward Ascorbic Acid-Related Bioanalysis in a “One-Stone-Two-Birds” Manner

“…Taking the in situ formed MnO x layer on the surface of CePO 4 :Tb into consideration, we deemed fluorescence resonance energy transfer (FRET) to be the most likely quenching mechanism. Subsequently, according to the three requirements for FRET (changed fluorescence lifetime, overlap of the donor absorption and recipient fluorescence spectra, and less than a 10 nm donor–acceptor distance), this conjecture was gradually tested . As shown in Figure S8B,D, the UV–vis absorption of MnO 2 nanoparticles shows a significant spectral overlap with the emission of CePO 4 :Tb, and the PL lifetime of CePO 4 :Tb is also shortened greatly after reacting with 0.4 mM KMnO 4 (2.838 ms for CePO 4 :Tb and 0.251 ms for CePO 4 :Tb@MnO x -0.4).…”

“…Subsequently, according to the three requirements for FRET (changed fluorescence lifetime, overlap of the donor absorption and recipient fluorescence spectra, and less than a 10 nm donor−acceptor distance), this conjecture was gradually tested. 42 As shown in Figure S8B,D, the UV−vis absorption of MnO 2 nanoparticles S1). Therefore, PL of CePO 4 :Tb@MnO x can also be suppressed by the MnO x layer on the surface of CePO 4 :Tb via a FRET process.…”

Integration of Manganese Dioxide‐Based Nanomaterials for Biomedical Applications

“…The fluorescence of CQDs could be effectively quenched by MnO 2 due to the fluorescence resonance energy transfer (FRET) process, and the quenched fluorescence signals were recovered in the presence of GSH with the detection limit of 15 μM. In addition, other MnO 2 -based fluorescence biosensors were established, such as gold nanoclusters-MnO 2 nanocomposite for detecting AA, [74] GSH [42] and H 2 O 2 , [75] dye-doped SiO 2 @MnO 2 core-shell nanocomposite for detecting GSH, [76] and semiconductor quantum dots@MnO2 nanoplatform for fluorescence imaging. [77] In addition to the fluorescence detection method based on the redox reaction between the substrates and MnO 2 , the high loading capacity of MnO 2 nanomaterials for the adsorption of nucleic acids makes MnO 2 nanomaterials an ideal DNA nanocarrier for tumor marker detection.…”

“…The fluorescence of CQDs could be effectively quenched by MnO 2 due to the fluorescence resonance energy transfer (FRET) process, and the quenched fluorescence signals were recovered in the presence of GSH with the detection limit of 15 μ m . In addition, other MnO 2 ‐based fluorescence biosensors were established, such as gold nanoclusters‐MnO 2 nanocomposite for detecting AA, [ 74 ] GSH [ 42 ] and H 2 O 2 , [ 75 ] dye‐doped SiO 2 @MnO 2 core–shell nanocomposite for detecting GSH, [ 76 ] and semiconductor quantum dots@MnO2 nanoplatform for fluorescence imaging. [ 77 ]…”

Two near-infrared phosphorescent iridium(iii) complexes for the detection of GSH and photodynamic therapy

“…Some nanomaterial-based probes also attract significant attention because of their excellent biocompatibility and spatial resolving power, but most of them need strict nanomaterial control in sizes and charges and handling complexity. [21][22][23][24] Compared to these probes, transition metal complexes, especially cyclometalated iridium(III) complexes, exhibit more advantages such as phosphorescence, large Stokes shifts, long luminescence lifetimes, high photostability and tunable emission wavelengths. [25][26][27] These advantageous properties are beneficial for the design of iridium(III) complex probes for photodynamic therapy (PDT), detecting the target and imaging in vivo by variation of the ligand.…”