Polymer nanoparticles (NPs) represent one of the most innovative non-invasive approaches for drug delivery applications. NPs main objective is to convey the therapeutic molecule be they drugs, proteins, or nucleic acids directly into the target organ or tissue. Many polymers are used for the synthesis of NPs and among the currently most employed materials several biocompatible synthetic polymers, namely polylactic acid (PLA), poly lactic-co-glycolic acid (PLGA), and polyethylene glycol (PEG), can be cited. These molecules are made of simple monomers which are naturally present in the body and therefore easily excreted without being toxic. The present review addresses the different approaches that are most commonly adopted to synthetize biocompatible NPs to date, as well as the experimental strategies designed to load them with therapeutic agents. In fact, drugs may be internalized in the NPs or physically dispersed therein. In this paper the various types of biodegradable polymer NPs will be discussed with emphasis on their applications in drug delivery. Close attention will be devoted to the treatment of cancer, where both active and passive targeting is used to enhance efficacy and reduce systemic toxicity, and to diseases affecting the central nervous system, inasmuch as NPs can be modified to target specific cells or cross membrane barriers.

Diseases affecting the central nervous system (CNS) are among the most disabling and the most difficult to cure due to the presence of the blood–brain barrier (BBB) which represents an impediment from a therapeutic and diagnostic point of view as it limits the entry of most drugs. The use of biocompatible polymer nanoparticles (NPs) as vehicles for targeted drug delivery to the brain arouses increasing interest. However, the route of administration of these vectors remains critical as the drug must be delivered without being degraded to achieve a therapeutic effect. An innovative approach for the administration of drugs to the brain using polymeric carriers is represented by the nose-to-brain (NtB) route which involves the administration of the therapeutic molecule through the neuro-olfactory epithelium of the nasal mucosa. Nasal administration is a non-invasive approach that allows the rapid transport of the drug directly to the brain and minimizes its systemic exposure. To date, many studies involve the use of polymer NPs for the NtB transport of drugs to the brain for the treatment of a whole series of disabling neurological diseases for which, as of today, there is no cure. In this review, various types of biodegradable polymer NPs for drug delivery to the brain through the NtB route are discussed and particular attention is devoted to the treatment of neurological diseases such as Glioblastoma and neurodegenerative diseases.

A strong impact of fluorophores’ charge and length on the binding mode, intracellular distribution and antiproliferative activity; intriguing theragnostic potential.

The growing interest in plant-origin active molecules with medicinal properties has led to a revaluation of plants in the pharmaceutical field. Plant-derived extracellular vesicles (PDEVs) have emerged as promising candidates for next-generation drug delivery systems due to their ability to concentrate and deliver a plethora of bioactive molecules. These bilayer membranous vesicles, whose diameter ranges from 30 to 1000 nm, are released by different cell types and play a crucial role in cross-kingdom communication between plants and humans. Notably, PDEVs have demonstrated efficacy in treating various diseases, including cancer, alcoholic liver disease, and inflammatory bowel disease. However, further research on plant vesicles is necessary to fully understand their traits and purposes. This study investigates the phototoxic effects of extracellular vesicles (EVs) from Aloe arborescens, Aloe barbadensis, and Aloe chinensis on the human melanoma cell line SK-MEL-5, focusing on their anthraquinone content, recognized as natural photosensitizers. The phototoxic impact of Aloe EVs is associated with ROS production, leading to significant oxidative stress in melanoma cells, as validated by a metabolome analysis. These findings suggest that EVs from Aloe arborescens, Aloe barbadensis, and Aloe chinensis hold promise as potential photosensitizers, thus highlighting their potential for future application in photodynamic cancer therapy and providing valuable insights into the possible utilization of PDEVs for therapeutic purposes.