A pan-cancer dye for solid-tumour screening, resection and wound monitoring via short-wave and near-infrared fluorescence imaging.

The efficacy of fluorescence-guided surgery in facilitating the real-time delineation of tumours depends on the optical contrast of tumour tissue over healthy tissue. Here we show that CJ215-a commercially available, renally cleared carbocyanine dye sensitive to apoptosis, and with an absorption and emission spectra suitable for near-infrared fluorescence imaging (wavelengths of 650-900 nm) and shortwave infrared (SWIR) fluorescence imaging (900-1,700 nm)-can facilitate fluorescence-guided tumour screening, tumour resection and the assessment of wound healing. In tumour models of either murine or human-derived breast, prostate and colon cancers and of fibrosarcoma, and in a model of intraperitoneal carcinomatosis, imaging of CJ215 with ambient light allowed for the delineation of nearly all tumours within 24 h after intravenous injection of the dye, which was minimally taken up by healthy organs. At later timepoints, CJ215 provided tumour-to-muscle contrast ratios up to 100 and tumour-to-liver contrast ratios up to 18. SWIR fluorescence imaging with the dye also allowed for quantifiable non-contact wound monitoring through commercial bandages. CJ215 may be compatible with existing and emerging clinical solutions.

Synthesis and Functionalization of Biodegradable Second Harmonic Generation Nanoprobes for Cell Targeting.

Optical imaging technologies and cell targeting have played a major role in detecting and treating diseases such as cancer. Bioharmonophores are optical imaging nanoprobes composed of biodegradable polymer-encapsulated, self-assembling triphenylalanine peptides. They produce a strong second harmonic generation (SHG) signal, a non-linear optical process in which two photons directed at a non-centrosymmetric medium combine to form a new photon with twice the energy. Bioharmonophores demonstrate superior optical properties compared to fluorescent probes and, unlike previously developed inorganic SHG nanoprobes, are both biocompatible and biodegradable. Here, we present a protocol providing five detailed procedures that describe (1) synthesis of bioharmonophores; (2) embedding and imaging of the synthesized SHG nanoprobes in polyacrylamide gel; (3) functionalization of bioharmonophores with thiol-containing polyethyleneglycol; (4) subsequent click chemistry to target cancer cells; and (5) imaging of functionalized bioharmonophores endocytosed by cancer cells using two-photon microscopy. Bioharmonophores hold great potential as clinical contrast agents due to their optical features and could be used in the future as an innovative approach to cancer treatment using targeted high-resolution optical imaging. © 2024 The Author(s). Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Synthesis of bioharmonophores Basic Protocol 2: Imaging of bioharmonophores in polyacrylamide gel Basic Protocol 3: Functionalization of bioharmonophores with thiol-PEG Basic Protocol 4: Functionalization of thiol-PEGylated bioharmonophores with peptides Basic Protocol 5: Targeting of cancer cells with functionalized bioharmonophores.

Biodegradable Harmonophores for Targeted High-Resolution In Vivo Tumor Imaging.

Optical imaging probes have played a major role in detecting and monitoring a variety of diseases. In particular, nonlinear optical imaging probes, such as second harmonic generating (SHG) nanoprobes, hold great promise as clinical contrast agents, as they can be imaged with little background signal and unmatched long-term photostability. As their chemical composition often includes transition metals, the use of inorganic SHG nanoprobes can raise long-term health concerns. Ideally, contrast agents for biomedical applications should be degraded in vivo without any long-term toxicological consequences to the organism. Here, we developed biodegradable harmonophores (bioharmonophores) that consist of polymer-encapsulated, self-assembling peptides that generate a strong SHG signal. When functionalized with tumor cell surface markers, these reporters can target single cancer cells with high detection sensitivity in zebrafish embryos in vivo. Thus, bioharmonophores will enable an innovative approach to cancer treatment using targeted high-resolution optical imaging for diagnostics and therapy.

Image Correlation Spectroscopy with Second Harmonic Generating Nanoparticles in Suspension and in Cells.

The absence of photobleaching, blinking, and saturation combined with a high contrast provides unique advantages of higher-harmonic generating nanoparticles over fluorescent probes, allowing for prolonged correlation spectroscopy studies. We apply the coherent intensity fluctuation model to study the mobility of second harmonic generating nanoparticles. A concise protocol is presented for quantifying the diffusion coefficient from a single spectroscopy measurement without the need for separate point-spread-function calibrations. The technique's applicability is illustrated on nominally 56 nm LiNbO3 nanoparticles. We perform label-free raster image correlation spectroscopy imaging in aqueous suspension and spatiotemporal image correlation spectroscopy in A549 human lung carcinoma cells. In good agreement with the expected theoretical result, the measured diffusion coefficient in water at room temperature is (7.5 ± 0.3) µm2/s. The diffusion coefficient in the cells is more than 103 times lower and heterogeneous, with an average of (3.7 ± 1.5) × 10-3 µm2/s.