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With difficulty in early diagnosis, inaccessibility for the surgical approach, and high resistance to radio and chemotherapies, the resulting low treatment success rates are calling for new approaches in treating pancreatic cancer [1]. Photodynamic therapy (PDT), with the use of light or X-rays, is a method that has the potential to help overcome the problems that existing approaches meet [2,3]. Through activation of photo-sensitive particles with irradiation, PDT helps the production of reactive oxygen species, consequently stimulating cell death. We have synthesized and characterized Gadolinium-doped titanium dioxide nanoparticles (Gd-TiO2 NPs) and tested them as photosensitizers on two pancreatic cancer cell lines, MIA PaCa-2 and PANC-1. Different concentrations of NP treatment, irradiation powers, and times of irradiation were trialed as parameters of activation. Cell viability was measured 48h after treatments, and although some results implied a slight decrease in the viability of treated cells, we have met difficulties in obtaining consistency in results. Statistical significance in the decrease of the viability of treated cells in most cases was not attained, suggesting that higher concentrations or irradiation power and longer illumination time might be needed to achieve a positive PDT effect with this NP system.

Carbon Dots (CDs) are biocompatible, fluorescent, water-soluble, and stable nanoparticles with a high potential to be used for vast biomedical applications [1,2]. We explore the application of CDs produced from natural sources, black carrots, as anti-cancer and imaging agents. These nanoparticles suppress cell growth of three different cancer cell lines, cervical (HeLa), pancreatic (PANC-1), and melanoma (A375) cell lines in vitro. However, the cytotoxic effect against A375 cells stands out, with only 20% of viable cells left after treatment (Fig.1(a)), antimetastatic potential, and a selectivity index higher than two, which indicates that the efficacy against melanoma cells is significantly greater than the toxicity against non-malignant cells (MRC-5). Furthermore, after the cellular uptake, green fluorescence was visible in the cytosol of A375 cells (Fig. 1 (b)). On the other hand, the DAPI stain for DNA was visible as a blue light in the cell nucleus. Moreover, cells with a higher intensity of green fluorescence in the nucleus, Fig. 1 (c) indicated with arrows, were the cells with condensed chromatin in the mitotic phase of the cell cycle (Fig. 1 (d) and (e)), which indicates that CDs interact with chromatin and that they could be used as a marker of cells mitosis and proliferation. In summary, we have demonstrated the great anti-cancer potential of black carrot CDs, for image-guided anti-cancer therapy of melanoma that can be used to recognize cell proliferation.

The promising strategy for targeted cancer treatment is to employ light as an external activator of a drug accumulated in tumor tissue. This approach is so-called photodynamic therapy (PDT) and can be used for diagnostic purposes. A photosensitizer, molecular oxygen, and laser light are the three significant components of Type II PDT, and the mechanism is the catalysis of the production of reactive oxygen species that lead to the oxidative damage of cellular molecules inducing cancer cell death [1]. Fluorescent carbon dots (CDs), spherical nanoparticles with size < 10 nm that can function as bioimaging agents and photosensitizers, have demonstrated significant potential in cancer theranostics [2]. Here, we have created Nitrogen co-doped carbon dots (N-CDs) surface decorated with organometallics compound, based on the Ru complex (Ru@N-CDs) [3,4] that were active in inducing biomolecular changes in ovarian cancer cell line upon illumination. Upon illumination, the most significant structural changes occurred in ovarian cancer cells and were detected in the protein region; we postulate interference with signaling pathways involved in regulating cancer cell growth and tumor progression. However, the limitation of light is the depth of penetration through the tissues, which prevents significant therapeutic effects on deep tumors. A strategy to overcome this is to use optical fibers that have coatings fabricated from the N-CDs, thus developing a so-called lab-on fiber system. The light propagating through the fiber [4] can activate the overall coating on the optical fiber surface with the presence of Ru@N-CDs. We hypothesize that the activation by the light results in the locally increased ROS production combined with enhanced release of the Ru complex from the surface, similar to the Ru@TiO2 NCS [5]. Our preliminary results demonstrate a high potential of the lab-on-fiber system in therapy against ovarian cancer that can resist traditional chemotherapeutic approaches.

Treating cancer remains a major challenge, despite the development of many therapies and advances in general knowledge about the disease. The treatments commonly used are invasive and non-selective, leading to severe side effects and unsatisfactory long-term outcomes. Nevertheless, external stimuli activating therapeutic agents in the affected area can be more beneficial than these aggressive therapies. Photodynamic therapy (PDT) is a minimally invasive, selective treatment that uses photosensitizer (PS) to damage cancer cells. The PS is activated by light, triggering a series of processes that produce reactive oxygen species (ROS), ultimately leading to cancer cell death. Numerous types of nanomaterial possess the capability to act as PS, one of which is TiO2 [1]. Although nanostructured TiO2 is biocompatible in the absence of light, its valence band electrons can be stimulated only by ultraviolet (UV) light irradiation. Since the penetration of UV light into tissue is limited, for application in PDT, nanostructured TiO2 can be doped with heteroatoms like N or C to allow visible light responsiveness [2,3]. This work evaluated the PS properties of unmodified nanostructured TiO2 (spherical nanoparticles TiO2 NPs and prolate nanospheroids, TiO2 PNSs) and doped TiO2 (N- and C-TiO2 NPs). After the synthesis, the size of TiO2 was confirmed to be in the nanoscale range (5-104 nm) by transmission electron microscopy [3,4]. The doped TiO2 was found to absorb visible light, as demonstrated by UV-Vis spectroscopy and bandgap calculations. Additionally, hydroxyl radicals were detected in water suspensions of TiO2 PNSs by electron paramagnetic resonance (EPR) spectroscopy, both with and without UV light illumination [4]. However, this radical was observed only with blue light stimulation of the water suspensions of N- and C-TiO2 NPs [3]. Cell experiments further revealed the internalization process of nanostructured TiO2 within cells, their cytotoxicity profiles, and the differ