Engineering ultrafine hyaluronic acid functionalized carrier-free nanoparticles by microfluidic precisely co-assembly for chemo/ photodynamic therapy

Nano drug delivery systems are a promising candidate for cancer treatment. However, its practical application is largely hindered by uncontrollable co-assembly, single function, low drug loading and lack of targeting ability. In this paper, the hyaluronic acid (HA) functionalized hydroxycamptothecine (HCPT) and photosensitizer TCPP (HA@H-T) carrier-free nanoparticles (NPs) are precisely prepared to obtain ultrafine nanostructure. The co-assembly process is explored with different microfluidic processes, NMR, FTIR and fluorescence quenching experiments. A possible two-step co-assembly mechanism is proposed to control the nucleation and growth process of HA@H-T. The HA is used as a structure-directing agent to manipulate the co-assembly at the liquid-solid interface between H-T NPs and HA solution. The confined interfacial co-assembly of HA would induce the heterogeneous growth to form the NPs with ultrafine particle size (76.6 +/- 0.4 nm) and small PDI (0.15 +/- 0.01). The HA@H-T exhibits enhanced tumor suppressive ability when tested with 4T1, A549 and HCT116 cells. HA@H-T has a high cellular uptake rate (87.4 %) and high ROS production levels (90.5 %). When exposed to near-infrared irradiation, the enhanced combined chemo/photodynamic therapy of HA@H-T is obtained in vivo animal experiments. This work paves a new avenue for the preparation of carrier-free NPs by microfluidic controllable co-assembly for chemo/photodynamic therapy.