Bioinspired urease-powered micromotor as an active oral drug delivery carrier in stomach

Self-propelling micro-and nano-motors(MNMs)have been extensively investigated as an emerging oral drug delivery carrier for gastrointestinal(GI)tract diseases.However,the propulsion of current MNMs reported so far is mostly based on the redox reaction of metals(such as Zn and Mg)with severe propulsion gas generation,remaining non-degradable residue in the GI tract.Here,we develop a bioinspired enzyme-powered biopolymer micromotor mimicking the mucin penetrating behavior of Helicobacter pylori in the stomach.It converts urea to ammonia and the subsequent increase of pH induces local gel-sol transition of the mucin layer facilitating the penetration into the stomach tissue layer.The successful fabrication of micromotors is confirmed by high-resolution transmission electron microscopy,electron energy loss spectroscopy,dynamic light scattering analysis,zeta-potential analysis.In acidic condition,the immobilized urease can efficiently converted urea to ammonia,comparable with that of neutral condition because of the increase of surrounding pH during propulsion.After administration into the stomach,the micromotors show enhanced penetration and prolonged retention in the stomach for 24 h.Furthermore,histological analysis shows that the micromotors are cleared within 3 days without causing any toxicity in the GI tract.The enhanced penetration and retention of the micromotors as an active oral delivery carrier in the stomach would be successfully harnessed for the treatment of various GI tract diseases.

Controlled afterglow luminescent particles for photochemical tissue bonding

Upconversion materials(UCMs)have been developed to convert tissue-penetrating near-infrared(NIR)light into visible light.However,the low energy conversion effciency of UCMs has limited their further biophotonic applications.Here,we developed controlled afterglow luminescent particles(ALPs)of ZnS:Ag,Co with strong and persistent green luminescence for photochemical tissue bonding(PTB).The co-doping of Ag^(+) and Co^(2+) ions into ZnS:Ag,Co particles with the proper vacancy formation of host ions resulted in high luminescence intensity and long-term afterglow.In addition,the ALPs of ZnS:Ag,Co could be recharged rapidly under short ultraviolet(UV)irradiation,which effectively activated rose bengal(RB)in hyaluronate-RB(HA-RB)conjugates for the crosslinking of dissected collagen layers without additional light irradiation.The remarkable PTB of ZnS:Ag,Co particles with HA-RB conjugates was confirmed by in vitro collagen fibrillogenesis assay,in vivo animal wound closure rate analysis,and in vivo tensile strength evaluation of incised skin tissues.Taken together,we could confirm the feasibility of controlled ALPs for various biophotonic applications.