research on developing nanoparticles with high drug loading (> 10 wt%) from the perspective of synthesis strategies, including post-loading, co-loading, and pre-loading. Based on these three different strategies, various nanoparticle systems with different materials and drugs are summarized and discussed in terms of their synthesis methods, drug loadings, encapsulation efficiencies, release profiles, stabilities, and their applications in drug delivery. The advantages and disadvantages of these strategies are presented with an objective of providing useful design rules for future development of high-drug-loading nanoparticles.

Lipid nanoparticles have attracted significant interests in the last two decades, and have achieved tremendous clinical success since the first clinical approval of Doxil in 1995. At the same time, lipid nanoparticles have also demonstrated enormous potential in delivering nucleic acid drugs as evidenced by the approval of two RNA therapies and mRNA COVID‐19 vaccines. In this review, an overview on different classes of lipid nanoparticles, including liposomes, solid lipid nanoparticles, and nanostructured lipid carriers, is first provided, followed by the introduction of their preparation methods. Then the characterizations of lipid nanoparticles are briefly reviewed and their applications in encapsulating and delivering hydrophobic drugs, hydrophilic drugs, and RNAs are highlighted. Finally, various applications of lipid nanoparticles for overcoming different delivery challenges, including crossing the blood–brain barrier, targeted delivery, and various routes of administration, are summarized. Lipid nanoparticles as drug delivery systems offer many attractive benefits such as great biocompatibility, ease of preparation, feasibility of scale‐up, nontoxicity, and targeted delivery, while current challenges in drug delivery warrant future studies about structure–function correlations, large‐scale production, and targeted delivery to realize the full potential of lipid nanoparticles for wider clinical and pharmaceutical applications in future.

Increasing drug loading remains a critical challenge in the development and translation of nanomedicine. High drug‐loading nanoparticles have demonstrated unique advantages such as less carrier material used, better‐controlled drug release, and improved efficacy and safety. Herein, we report a simple and efficient salt concentration screening method for making polymer nanoparticles with exceptionally high drug loading (up to 66.5 wt%) based on phase separation‐induced nanoprecipitation. Upon addition of salt, phase separation occurs in a miscible solvent‐water solution delaying the precipitation time of drugs and polymers to different extents, facilitating their co‐precipitation thus the formation of high drug‐loading nanoparticles with high encapsulation efficiency (>90%) and excellent stability (>1 month). This technology is versatile and easy to be adapted to various hydrophobic drugs, different polymers, and solvents. This salt‐induced nanoprecipitation strategy offers a novel approach to fabricating polymer nanoparticles with tunable drug loading, and opens great potentials for future nanomedicines.

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