Mobile multi-configuration clinical translational Raman system for oral cancer application.

Early diagnosis of oral cancer is critical to improve the survival rate of patients. Raman spectroscopy, a non-invasive spectroscopic technique, has shown potential in identifying early-stage oral cancer biomarkers in the oral cavity environment. However, inherently weak signals necessitate highly sensitive detectors, which restricts widespread usage due to high setup costs. In this research, the fabrication and assembly of a customised Raman system that can adapt three different configurations for the in vivo and ex vivo analysis is reported. This novel design will help in reducing the cost required to have multiple Raman instruments specific for a given application. First, we demonstrated the capability of a customized microscope for acquiring Raman signals from a single cell with high signal-to-noise ratio. Generally, when working with liquid samples with low concentration of analytes (such as saliva) under a microscope, excitation light interacts with a small sample volume, which may not be representative of whole sample. To address this issue, we have designed a novel long-path transmission set-up, which was found to be sensitive towards low concentration of analytes in aqueous solution. We further demonstrated that the same Raman system can be incorporated with the multimodal fibre optical probe to collect in vivo data from oral tissues. In summary, this flexible, portable, multi-configuration Raman system has the potential to provide a cost-effective solution for complete screening of precancer oral lesions.

Photodynamic-induced vascular damage of the chick chorioallantoic membrane model using perylenequinones.

The chorioallantoic membrane (CAM) assay is a widely used bioassay in early in vivo cancer research. The CAM allows non-invasive study of in vivo microvasculature and blood circulation. This report describes the first topical application investigation of photodynamic response in the CAM model using Hypericin (HY) and Hypocrellin B (HB) that belongs to the perylenequinone family. Briefly, cultivated carcinoma of the human bladder cell line (MGH), were inoculated on the CAM of fertilized eggs of embryo age (EA) 9. Tumor growth was evaluated by digital stereomicroscopy. Photodynamic therapy (PDT) was performed following topical application of the photosensitizers. We were able to demonstrate that these perylenequinones localized selectively in the xenografted bladder tumor and in the vasculature of the CAM. Photodynamic treatments were performed using a custom-made non-laser light source coupled into a flexible fiber bundle to selectively excite the photosensitizers in order to induce photodamage to the tumor and vasculature. The vascular damage induced was quantitatively measured following topical application of the photosensitizers. Both photosensitizers exhibited very similar degrees of photodamage to the CAM. The CAM model offers an exciting avenue for the study of PDT induced effect on the vasculature. Our preliminary results support that the CAM model could potentially serve as a customized model to study photodynamic therapy effects of various photosensitizers on specific tumor models.