Microfluidic channel engineering for mRNA–LNPs: a systematic review of mixing strategies, nanostructures, and biological performance

mRNA-lipid nanoparticles (mRNA-LNPs) have revolutionized nucleic acid therapeutics, yet their clinical success relies heavily on precise manufacturing processes. This review comprehensively explores the critical intersection between microfluidic channel design, lipid self-assembly biophysics, and the subsequent biological performance of mRNA-LNPs. First, we analyze the fundamental fluid mechanics driving representative microfluidic mixers, elucidating how different channel architectures dictate solvent exchange rates and nanoparticle assembly kinetics. We then systematically examine how these specific mixing regimes modulate essential physicochemical characteristics, including lipid distribution, internal nanostructure, particle morphology, size distribution, and overall colloidal stability. Crucially, we bridge the gap between manufacturing and pharmacology by evaluating how mixing-induced physicochemical differences directly translate into distinct biological outcomes, such as cellular uptake mechanisms, endosomal escape efficiency, and systemic pharmacokinetics. By integrating microfluidic engineering principles with biological evaluation, this review provides a mechanistic framework for understanding how continuous-flow assembly processes program the functional behavior of mRNA-LNP systems. Ultimately, we highlight emerging design principles essential for developing the next generation of robust, highly efficient nucleic acid delivery platforms.