A Review of the Structure, Preparation, and Application of NLCs, PNPs, and PLNs

Abstract

Nanostructured lipid carriers (NLCs) are modified solid lipid nanoparticles (SLNs) that retain the characteristics of the SLN, improve drug stability and loading capacity, and prevent drug leakage. Polymer nanoparticles (PNPs) are an important component of drug delivery. These nanoparticles can effectively direct drug delivery to specific targets and improve drug stability and controlled drug release. Lipid-polymer nanoparticles (PLNs), a new type of carrier that combines liposomes and polymers, have been employed in recent years. These nanoparticles possess the complementary advantages of PNPs and liposomes. A PLN is composed of a core-shell structure; the polymer core provides a stable structure, and the phospholipid shell offers good biocompatibility. As such, the two components increase the drug encapsulation efficiency rate, facilitate surface modification, and prevent leakage of water-soluble drugs. Hence, we have reviewed the current state of development for the NLCs', PNPs', and PLNs' structures, preparation, and applications over the past five years, to provide the basis for further study on a controlled release drug delivery system.

Keywords: applications; lipid–polymer hybrid nanoparticles; nanostructured lipid carriers; polymeric nanoparticles; preparation; structure.

Figure 1

Schematic diagram illustrating structures of NLCs (1, 2, and 3 are disorder structure, amorphous structure and multiple structure, respectively).

Figure 2

Schematic diagram illustrating structures of two types of PNPs. 1 and 2 are polymer nanospheres and polymer nanocapsules, respectively.

Figure 3

Schematic diagram illustrating the structure of PLNs. 1, monolithic matrix structure; 2, core–shell structure. (A) Monolithic matrix PLN with polymer–drug complex; (B) monolithic matrix PLN with siRNA–polymer complex; (C,D) core–shell PLN with drug in the core; (E) core–shell PLN with siRNA at the core–shell interface.