Application of microreactor constructed with micro-mixing channel featuring 3D lateral secondary flow structure for ultra-small particle size preparation of magnetic chitosan nanodrug carriers

Magnetic chitosan nanoparticles serve as reliable carriers for drug delivery, but conventional macroscopic synthesis methods are associated with a number of disadvantages. Efficient micromixing is a crucial aspect of the controlled synthesis of nanoparticles. The addition of lateral structures to the microchannel sidewalls has been demonstrated to be an effective method for enhancing mixing performance at low Re. A high-efficiency microreactor (3D(S)-SWM) was constructed by combining the spherical (S) 3D lateral structure with the square wave (SW) channel. The introduction of the 3D lateral structure enables the rapid preparation of magnetic chitosan nanoparticles at low Re. The production of a product with a particle size as low as 18–26 nm, while maintaining superparamagnetic. This has significant implications for the targeted transport of drug carriers and their metabolism in vivo. It is anticipated that 3D(S)-SWM will expand the scope of drug delivery applications and facilitate the treatment of diseases. [Display omitted] •Four 3D lateral structures were proposed to enhance micromixing at low Re.•The effect of multi-dimensional secondary flow effect on mixing efficiency was studied in detail.•The screened 3D(S)-SWM had the best mixing performance.•Magnetic chitosan nanoparticles with ultra-small particle size were prepared at low Re using 3D(S)-SWM. Magnetic chitosan nanoparticles serve as reliable carriers for drug delivery, but conventional macroscopic synthesis methods are associated with a number of disadvantages. Efficient micromixing is a crucial aspect of the controlled synthesis of nanoparticles. However, enhancing the mixing efficiency of micromixers at low Reynolds numbers (Re) remains a significant challenge. Fortunately, the addition of lateral structures to the microchannel sidewalls has been demonstrated to be an effective method for enhancing mixing performance at low Re. In this work, the secondary flow effect of 3D lateral structure was numerically studied, and the reason why the multi-dimensional secondary flow effect can effectively promote mixing was analyzed. A high-efficiency microreactor (3D(S)-SWM) was constructed by combining the spherical (S) 3D lateral structure with the square wave (SW) channel. In comparison to other microreactors, 3D(S)-SWM exhibits a shorter full mixing cycle and a smaller pressure drop. Magnetic chitosan nanoparticles were prepared in one step by using the 3D(S)-SWM. The introduction of the 3D lateral s