Carrageenan, a polysaccharide derived from red seaweeds, is commonly used to induce inflammation in animal models for studying inflammatory diseases. Its pro-inflammatory effects involve several key mechanisms: Activation of the Immune System: Carrageenan stimulates local immune cells, particularly macrophages, leading to an increased release of pro-inflammatory cytokines such as TNF-α, IL-1β, and IL-6. Disruption of Epithelial Barrier: It causes damage to the intestinal epithelial barrier, increasing intestinal permeability and facilitating the entry of pathogens and toxins, which exacerbates inflammation. Production of Inflammatory Mediators: Carrageenan enhances the production of inflammatory mediators like prostaglandins and leukotrienes, contributing to inflammation and pain. Modulation of Signaling Pathways: It affects important signaling pathways, including NF-κB and MAPK, which are crucial in regulating the inflammatory response. These mechanisms make carrageenan a valuable tool for studying inflammatory processes and evaluating the efficacy of anti-inflammatory treatments in animal models.

In prostate cancer treatment, Photodynamic Therapy (PDT) is being explored in combination with various modalities [1]. PDT coupled with surgery, particularly salvage radical prostatectomy after vascular-targeted PDT (VTP), shows promise for treating recurrent or persistent cancer. While PDT alongside Sonodynamic Therapy (SDT) is a developing area, preclinical studies suggest its potential in damaging cancer cell membranes through sensitizers. PDT with Photoimmunotherapy (PIT) induces antitumor immune responses and selectively destroys cancer cells, especially when targeting specific markers like prostate-specific membrane antigen (PSMA). Innovative Photochemotherapy, merging PDT and chemotherapy, offers selective drug delivery to tumor cells, supported by in vivo studies [2][3][4]. Photothermal Therapy (PTT), a heat-based phototherapy, complements PDT by improving local blood flow and oxygen levels in tumor tissues, albeit with challenges in material efficiency. These diverse PDT combinations signify evolving prospects in prostate cancer treatment.

Technologically useful functionalities can be found in a number of nature-made 2D nanostructures coming from the worlds of minerals, fossils, meteorites, plants, etc. For example, some layered natural 2D-nanomaterials have mirror-like capability. In particular, when a bi-layered material is made of sheets characterized by very different refractive index values, it behaves like a mirror capable to effectively reflect visible light. A number of mineral substances have a layered structure made of two or more layers of different refractive indices and White-Kaolin could be considered as the most representative example of such special bi-layered nanostructures. Owing to the very good ‘white point’ (i.e., achromatic reflectance) and planar shape, White-Kaolin is a two-dimensional natural nanostructure characterized by exceptional mattifying properties. The high visible reflectance of White-Kaolin platelets is due to its crystalline structure with layers made of silica and aluminium hydroxide (the refractive indices are 1.5 and 1.8, respectively). Since single White-Kaolin lamellas specularly reflect photons of the full visible spectral region, a coating layer made of variously oriented Kaolin sheets (i.e., a non-coplanar distribution of these natural ‘nano-mirrors’) is capable to effectively scatter the visible light (that is, to produce a diffuse light reflection). This unique property of White-Kaolin-based coatings has been exploited for different optical applications like, for example, the light-diffusing layer placed inside the white incandescent light bulbs (White-Kaolin is a refractory material capable to withstand the high temperatures generated by the tungsten filament) and gas-discharge lamps [1]. However, the high achromatic reflectance of this 2D nanostructures are also exploited in white plasters for construction, paints, varnishes, and many other industrial applications. A further interesting potentiality of the White-Kaolin mineral is its unique capability of producing stable colloidal suspensions by simply dispersing the mineral in water (the water molecules permeate the crystal and break the hydrogen bond bridges among the silica and aluminium hydroxide layers in the crystal).

Dark matter is a form of matter that does not emit, absorb or reflect light, so we cannot see it directly; we infer its existence via gravitational effects. It makes up about 27% of the universe’s total mass–energy content, while ordinary (visible) matter is only ~5%. In galaxies, stars orbit at speeds that cannot be explained by visible matter alone; the extra gravitational pull implies unseen mass (dark matter). It doesn’t behave like light-emitting or interacting matter: it’s “electromagnetically neutral” (no strong interaction with light), and probably moves slowly (“cold”) in cosmological terms.

Colored polymers are quite a rarity; indeed, there are a few families of linear polymers showing coloration usually ranging from pale-yellow to dark brown (most polymers are amber colored). These polymers belong to the high performance thermoplastics class (e.g., polyarylsulfones, polyimides, polyamideimides, etc.). The visible coloration is frequently associated with a high optical transparency (i.e., absence of light-scattering phenomena), which occurs for the amorphous nature of these solids. These solids are characterized by a sharp transparency change at a special wavelength, named cut-off. Precisely, they are very transparent at wavelengths higher than the cut-off wavelength and completely opaque at wavelengths below the cut-off wavelength. Since optical absorption of inherently colored polymers extends up to the visible spectral region, these solids are capable to completely absorb ultraviolet photons (that is, UV-C sub-band, like most of plastics do, but also the UV-B and UV-A sub-bands). The absorption coefficient of these polymers is very high and, consequently, they can completely block the ultraviolet radiation unless they are processed in form of thin films or coatings. It must be pointed out that common dyed plastics are obtained by dissolving an organic colorant into a plastic material and consequently the resulting optical absorption comes from the chromophores present in this organic molecule. Intrinsic/inherent coloration has a completely different nature, it is due to a huge bell-shaped absorption band, extending over a wide spectral range, which is generated by photoexcitation of electrons contained in the valence band states to the empty conduction band states. These inherently colored polymeric optical media constitute a niche class of polymeric materials potentially useful in the optical fields for technological applications like optical limiters, UV-shielding optical windows, color filters, etc.