Lipid nanoparticles: state of the art, new preparation methods andchallenges in drug delivery

Introduction: Nanoparticles are rapidly developing as drug carriers because of their size-dependent properties. Lipid nanoparticles (LNPs) are widely employed in drug delivery because of the biocompatibility of the lipid matrix. Areas covered: Many different types of LNPs have been engineered in the last 20 years, the most important being solid lipid nanoparticles (SLNs), nanostrucured lipid carriers (NLCs), lipid--drug conjugates (LDCs) and lipid nanocapsules (LNCs). This review gives an overview of LNPs, including their physico-chemical properties and pharmacological uses. Moreover, it highlights the most important innovations in the preparation techniques of LNPs, aimed to encapsulate different molecules within the lipid matrix. Finally, it gives a short perspective on the challenges of drug delivery, which are a potential field of application for LNPs: cancer therapy, overcoming the blood--brain barrier and gene and protein delivery. Expert opinion: LNPs are a safe and versatile vehicles for drug and active delivery, suitable for different administration routes. New technologies have been developed for LNP preparation and studies are currently underway in order to obtain the incapsulation of different drugs and to deliver the active molecule to the site of action.