Plasmonic enhancement of cyanine dyes for near-infrared light-triggered photodynamic/photothermal therapy and fluorescent imaging

Abstract

Near-infrared (NIR) triggered cyanine dyes have attracted considerable attention in multimodal tumor theranostics. However, NIR cyanine dyes used in tumor treatment often suffer from low fluorescence intensity and weak singlet oxygen generation efficiency, resulting in inadequate diagnostic and therapy efficacy for tumors. It is still a great challenge to improve both the photodynamic therapy (PDT) and fluorescent imaging (FLI) efficacy of cyanine dyes in tumor applications. Herein, a novel multifunctional nanoagent AuNRs@SiO-IR795 was developed to realize the integrated photothermal/photodynamic therapy (PTT/PDT) and FLI at a very low dosage of IR795 (0.4 μM) based on metal-enhanced fluorescence (MEF) effects. In our design, both the fluorescence intensity and reactive oxygen species of AuNRs@SiO-IR795 nanocomposites were significantly enhanced up to 51.7 and 6.3 folds compared with free IR795, owing to the localized surface plasmon resonance band of AuNRs overlapping with the absorption or fluorescence emission band of the IR795 dye. Under NIR laser irradiation, the cancer cell inhibition efficiency in vitro with synergetic PDT/PTT was up to 82.3%, compared with 10.3% for free IR795. Moreover, the enhanced fluorescence intensity of our designed nanocomposites was helpful to track their behavior in tumor cells. Therefore, our designed nanoagents highlight the applications of multimodal diagnostics and therapy in tumors based on MEF.

Light Scattering versus Plasmon Effects: Optical Transitions in Molecular Oxygen near a Metal Nanoparticle

“…If we limit ourselves to experiments that investigate possible plasmonic effects on the production and removal of O 2 (a 1 Δ g ), the list is still remarkably long. 16,[18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35]38 (The references cited represent only a fraction of the published literature.) In looking at many of these latter studies, we find reported enhancement factors that fall in the range of ∼0.5−2.0.…”

Heptamethine Cyanine–Based Application for Cancer Theranostics

“…Although the PTT and PDT of heptamethine and the derivatives as photosensitizers have potential for cancer therapy, any single phototherapy modality has limitations in large and deep vivo tumor therapy according to clinical observation due to the significant therapeutic effects decreasing over time (Luo et al, 2016;Lu et al, 2017;Cao et al, 2019;Xue et al, 2019). Compared with conventional single therapy, multimodal therapies integrating PDT and PTT, have been more widely applied in tumor treatment because they hybrid the merits of light-guided therapy, exhibiting relatively low toxicity, negligible metastasis, recurrence of tumor, and significantly improving the therapeutic effect (Luo et al, 2016;Lu et al, 2017;Xue et al, 2019). In vivo and in vitro safety assessment showed the low cytotoxicity of CyI.…”

Cyanine conjugates in cancer theranostics

“…Such complexity was best exemplified by Au-based nanomaterials with various morphology, e.g., Au nanorods, Au nanostars, Au nanoclusters. In these conjugates, cyanine fluorophores could be covalently conjugated to Au nanomaterials via Au–S bond [ 61 , 62 ], or indirectly modified through polymer coating [ 63 ], complementary base pairing [ 64 ] etc. ; and many conjugates also exhibited off-on fluorescence/PDT response towards internal stimuli such as pH, GSH, cathepsin E and matrix metalloproteinases (MMPs).…”