Multifunctional hybrid nanoparticles for biomedical applications

Nanomedicine has proven to be a promising avenue for the diagnosis and treatment of various diseases, offering customised solutions that are more specific and effective compared to conventional methods. The main components of nanomedicine are engineered nanoparticles (NPs), which can be produced from a variety of materials. Organic, inorganic, metallic, and polymeric NPs, including dendrimers, micelles, and liposomes, are examples of NPs that are widely explored in nanomedicine. Among them, inorganic NPs offer several advantages, such as tunable size and surface chemistry, high surface-to-volume ratio, chemical stability, biocompatibility, and unique optical, magnetic and electrical properties.

In this work, the use of porous biosilica-based NPs is described for biomedical applications. The NPs are derived from diatomite, a material of sedimentary origin formed from the remains of diatom skeletons. Diatomite-based NPs (DNPs) can be produced in a size range between 100 and 400 nm by a mechanical process based on ultrasound application and filtering. DNPs are characterized by a porous morphology, which is useful for the efficient loading of drugs. Moreover, they can be made photoluminescent for imaging purposes. The biocompatibility and cellular uptake of DNPs are demonstrated using different cancer cell lines, including human epidermoid, breast, cervical, and colorectal cancer cells. The silica surface can be chemically modified by various functionalization strategies to increase the drug uptake capacity of DNPs and improve the pharmacokinetic and pharmacodynamic profiles of the delivered drugs.

A hybrid nanosystem constituted by DNPs covered by gold NPs acting as SERS substrates is proposed for simultaneous intracellular drug sensing and delivery. This nanosystem constitutes the first example of a multifunctional platform realized from diatomite. Active targeting strategies, performed by immobilizing ligands on NPs, are also explored to enhance drug delivery efficiency^.