Tissue-mimicking phantom materials with tunable optical properties suitable for assessment of diffuse reflectance spectroscopy during electrosurgery

Gelatin-containing porous polycaprolactone PolyHIPEs as substrates for 3D breast cancer cell culture and vascular infiltration

Tumour survival and growth are reliant on angiogenesis, the formation of new blood vessels, to facilitate nutrient and waste exchange and, importantly, provide a route for metastasis from a primary to a secondary site. Whilst current models can ensure the transport and exchange of nutrients and waste via diffusion over distances greater than 200 μm, many lack sufficient vasculature capable of recapitulating the tumour microenvironment and, thus, metastasis. In this study, we utilise gelatin-containing polymerised high internal phase emulsion (polyHIPE) templated polycaprolactone-methacrylate (PCL-M) scaffolds to fabricate a composite material to support the 3D culture of MDA-MB-231 breast cancer cells and vascular ingrowth. Firstly, we investigated the effect of gelatin within the scaffolds on the mechanical and chemical properties using compression testing and FTIR spectroscopy, respectively. Initial in vitro assessment of cell metabolic activity and vascular endothelial growth factor expression demonstrated that gelatin-containing PCL-M polyHIPEs are capable of supporting 3D breast cancer cell growth. We then utilised the chick chorioallantoic membrane (CAM) assay to assess the angiogenic potential of cell-seeded gelatin-containing PCL-M polyHIPEs, and vascular ingrowth within cell-seeded, surfactant and gelatin-containing scaffolds was investigated via histological staining. Overall, our study proposes a promising composite material to fabricate a substrate to support the 3D culture of cancer cells and vascular ingrowth.

Diffuse reflectance spectroscopy of the spine: improved breach detection with angulated fibers

Accuracy in spinal fusion varies greatly depending on the experience of the physician. Real-time tissue feedback with diffuse reflectance spectroscopy has been shown to provide cortical breach detection using a conventional probe with two parallel fibers. In this study, Monte Carlo simulations and optical phantom experiments were conducted to investigate how angulation of the emitting fiber affects the probed volume to allow for the detection of acute breaches. Difference in intensity magnitude between cancellous and cortical spectra increased with the fiber angle, suggesting that outward angulated fibers are beneficial in acute breach scenarios. Proximity to the cortical bone could be detected best with fibers angulated at θ f = 45 ∘ for impending breaches between θ p = 0 ∘ and θ p = 45 ∘ . An orthopedic surgical device comprising a third fiber perpendicular to the device axis could thus cover the full impending breach range from θ p = 0 ∘ to θ p = 90 ∘ .