Indocyanine green-loaded gold nanostars for sensitive SERS imaging and subcellular monitoring of photothermal therapy

Abstract

We have demonstrated that a typical nanothermometer was incorporated in a bovine serum albumin stabilized gold nanostar-indocyanine green (denoted as GNS-ICG-BSA) nanoprobe to realize surface-enhanced Raman scattering (SERS) imaging-based real-time sensitive monitoring of intracellular temperature in photothermal therapy (PTT), which significantly improved the spatial resolution compared to infrared thermal imaging. Herein, an exogenous thermosensitive molecule, ICG, acting as a tri-functional agent, was selected as the Raman reporter instead of direct cellular biochemical changes. The triggering of the obtained probe was unaffected by the cellular microenvironment, so it can act as a monitor of PTT in various cell types. High-resolution mass spectrometry (HRMS) was used to investigate the thermosensitive mechanism of ICG. The actively targeted GNS-ICG-BSA nanotags were used to induce SERS mapping-guided in vitro PTT of U87 glioma cells. Meanwhile, small temperature variations within a cell during PTT can be precisely monitored through the SERS fingerprint information, with a spatial resolution at the subcellular level and a sensitivity of 0.37 °C. Thus, the integrated GNS-ICG-BSA nanotags can be treated as a theranostic probe, a SERS imaging probe and an intracellular thermometer. Moreover, the good biocompatibility and the low cytotoxicity of GNS-ICG-BSA nanotags, together with their superior photothermal ablation effect on U87 glioma cells have been confirmed. This suggested that the implanted nanothermometry approach would be promising for a better understanding of the biological processes at subcellular level and provide new insights into the fabrication of a multifunctional nanoplatform. Furthermore, this study revealed that the SERS-based monitoring technique can offer great potential for theranostics as an emerging strategy.

Mutual impact of clinically translatable near-infrared dyes on photoacoustic image contrast and in vitro photodynamic therapy efficacy

“…J-aggregated ICG molecules or conjugation to plasmonic nanoparticles are shown to enhance ICG photostability. [51][52][53] The photodegradation properties of ICG are also cleverly utilized for drug delivery strategies as reviewed recently by Gorka and Schnermann. 51 Furthermore, ICG was shown to have enhanced photostability via encapsulation in lipids or association with plasmonic gold colloids.…”

Förster Resonance Energy Transfer-Based Dual-Modal Theranostic Nanoprobe for In Situ Visualization of Cancer Photothermal Therapy

“…This demonstrates that HSA-ICG-MB NPs are efficient photothermal transducers to produce significant hyperthermia (>42 o C). 52 During photothermal heating, the ICG molecules in NPs gradually decompose 53 , 54 , and their FRET efficiency accordingly decreases, resulting in changes in the fluorescence and PA signals of the donor-acceptor pair. It was observed that with increasing temperature, the fluorescence intensity of ICG (centered at 810 nm) decreased, while MB emission (centered at 685 nm) enhanced correspondingly (Figure 2 c).…”

“…During the process, the fluorescence signal from MB gradually rose, and the fluorescence emission from ICG decreased monotonically with prolonged irradiation time from 0 to 5 min (Figure 3 b). These changes stem from photothermal decomposition of ICG in NPs, 54 decreasing the FRET efficiency. Therefore, FRET-based dual-channel fluorescence imaging can be applied for clear visualization of the cellular therapeutic responses.…”

Advances in surface‐enhanced Raman spectroscopy for cancer diagnosis and staging

“…Nucleic acid sequences extracted from clinical samples were amplified before SERS detection. For instance, RNA was extracted from the urine of prostate cancer patients and amplified using multiplex reverse transcription recombinase polymerase amplification . Discrimination among healthy and cancer patients was attained using principal component analysis linear discriminant analysis (PCA‐LDA) analysis with sensitivity and specificity of 89.1% and 95.6% for colorectal cancer and 100% and 94.1% for gastric cancer.…”