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.

Clostridium botulinum is a bacterium commonly found in soil, sediments, and sometimes in the intestines of animals. Under certain conditions, such as low-oxygen environments, it produces botulinum toxin—one of the most potent toxins known to science. Botulism is the illness caused by this toxin. It affects the nervous system, leading to muscle weakness, paralysis, and in severe cases, death if untreated.

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.

(A) Utilizing Boronic Acid-Decorated Polymers for Intracellular Protein Delivery with Polyphenols. Polyphenols play a critical role in enhancing the interaction between polymers containing boronic acid and proteins. In an acidic environment, the pH-responsive catechol–boronate bonds form between the boronic acid-conjugated polymers and polyphenols, enabling the controlled release of RNase. This release can induce cell death by selectively targeting and degrading specific RNA molecules [1]. (B) Enhancing Chemodynamic Therapy (CDT) through the DOX−Den Complex with TA−Fe3+ MPN. The DOX−Den complex efficiently transports doxorubicin (DOX) into cancer cells while evading drug efflux transporters on the cell membrane. Within the cells, DOX is transported to the cell nuclei through the Fenton reaction-mediated CDT. This process leads to the generation of an excess of reactive oxygen species (ROS), ultimately resulting in the elimination of drug-resistant cancer cells [1]. (C) Combining Immune Checkpoint Blockade and Photodynamic Therapy using MMP-2-Sensitive PEGylated EGCG Dimers. PEGylated EGCG dimers and EGCG dimers are utilized to facilitate a novel approach that combines immune checkpoint blockade with photodynamic therapy. Upon activation by MMP-2, the nanoparticles release αPD-L1/ICG, with the antibody effectively blocking the PD-L1 checkpoint. Simultaneously, illumination of the photosensitizer induces multiple effects, including the generation of reactive oxygen species (ROS) and cell death. This innovative approach holds promise for cancer treatment [1].