Engineered extracellular vesicles: A new approach for targeted therapy of tumors and overcoming drug resistance

Targeted delivery of anti-tumor drugs and overcoming drug resistance in malig-nant tumor cells remain significant clinical challenges.However,there are only few effective methods to address these issues.Extracellular vesicles(EVs),actively secreted by cells,play a crucial role in intercellular information transmis-sion and cargo transportation.Recent studies have demonstrated that engineered EVs can serve as drug delivery carriers and showed promising application prospects.Nevertheless,there is an urgent need for further improvements in the isolation and purification of EVs,surface modification techniques,drug assem-bly processes,and precise recognition of tumor cells for targeted drug delivery purposes.In this review,we summarize the applications of engineered EVs in cancer treatment and overcoming drug resistance,and current challenges asso-ciated with engineered EVs are also discussed.This review aims to provide new insights and potential directions for utilizing engineered EVs as targeted delivery systems for anti-tumor drugs and overcoming drug resistance in the near future.

Synthesis,Crystal Structure and Luminescent/magnetic Properties of Two Metal-organic Frameworks Based on Multi-N/O-donor Mixed Ligands

Two new complexes,namely[Cd_(2)(L)(pycy)(Cl)]·2H_(2)O(1)and[Cu(HL)(H_(2)btac)]·2 H_(2)O,have been synthesized by the reaction of the corresponding metal salts with mixed ligands including 1-(1 H-imidazol-4-yl)-4-(4 H-tetrazol-5-yl)benzene(HL),2,6-pyridinedicarboxylic acid(H_(2)pycy)and 1,2,4,5-benzenetetracarboxylic acid(H4 btac),and characterized by single-crystal X-ray diffraction,IR spectroscopy,elemental analysis and powder X-ray diffraction(PXRD).Complex 1 crystallizes in triclinic,space group P1 with a=9.8938(7),b=10.1662(7),c=12.4520(8)A,α=92.7070(10),β=108.1310(10),γ=105.3230(10)°,V=1136.44(13)A^(3),Z=2,C_(17)H_(12)N_(7)O_(6)Cl Cd_(2),M_(r)=670.59,D_(c)=1.960 g/cm^(3),μ=2.037 mm^(-1),S=1.062,F(000)=648,the final R=0.0532 and w R=0.1651 for 12156 observed reflections(I>2σ(I)).Complex 2 crystallizes in triclinic,space group P1 with a=7.3058(8),b=7.4890(8),c=10.8937(12)?,α=71.3810(10),β=84.134(2),γ=65.745(2)°,V=514.68(10)A^(3),Z=1,C_(20)H_(16)Cu N_(6)O_(10),M_(r)=563.94,D_(c)=1.819 g/cm^(3),μ=1.139 mm^(-1),S=1.187,F(000)=287,the final R=0.0314 and w R=0.0807 for 3564 observed reflections(I>2σ(I)).Single-crystal X-ray structural analysis reveals that complex 1 features a trinodal(3,3,4)-connected two-dimensional(2 D)net layer with Schlafli symbol(4·6·8)(4·6^(2)·8^(3))(6^(2)·8)while 2 has a 2 D network with 4^(4)sql topology.Moreover,the photoluminescent property of 1 and magnetic property of 2 were also discussed.

Size engineering of 2D MOF nanosheets for enhanced photodynamic antimicrobial therapy

Although porphyrin-based metal-organic frameworks(MOFs)have been widely explored as photosensitizers for photodynamic therapy,how the size will affect the light-induced catalytic activity for generation of reactive oxygen species(ROS)still remain unclear.Herein,we first report the size-controlled synthesis of two-dimensional(2D)porphyrin-based PCN-134 MOF nanosheets by a two-step solvothermal method to explore the size effect on its PDT performance,thus yielding enhanced photodynamic antimicrobial therapy.By simply controlling the reaction temperature in the synthesis process,the bulk PCN-134 crystal,large PCN-134(L-PCN-134)nanosheets with a lateral size of 2–3μm and thickness of 33.2–37.5 nm and small PCN-134 nanosheets(S-PCN-134)with a lateral size of 160–180 nm and thickness of 9.1–9.7 nm were successfully prepared.Interestingly,the S-PCN-134 nanosheets exhibit much higher photodynamic activity for ROS generation than that of the bulk 3D PCN-134 crystal and L-PCN-134 nanosheets under a660 nm laser irradiation,suggesting that the photodynamic activity of PCN-134 MOF increases when the size reduces.Therefore,the S-PCN-134 nanosheets show much enhanced performance when used as a photosensitizer for photodynamic antimicrobial activity and wound healing.

Membrane-targeting amphiphilic AIE photosensitizer for broad-spectrum bacteria imaging and photodynamic killing of bacteria

An amphiphilic AIE photosensitizer has been successfully developed,which allows for easily inserting into the bacterial membranes.Binding experiments with phospholipid preliminary demonstrates its membrane specificity.As expected,it is proved to possess a broad-spectrum bacterial staining performance and photodynamic antibacterial activity toward S.aureus and E.coli.

Efficient blue light-responsed dithienylethenes with exceptional photochromic performance

Three novel dithienylethenes modified by bifluoroboron β-diketonate fragments have been successfully developed. Upon blue light irradiation, they reached photostationary state within 2-5 s, as well as 100% conversion ratio and photocyclization quantum yield of > 0.70. Such fascinating photochromism were endowed by collaborative role of electron-withdrawing effect of BF_(2)bdk group to reduce HOMO-LUMO electronic gap for the open isomer, together with intramolecular hydrogen bonds and CH-π interactions favoring antiparallel conformation fixation. Moreover, they displayed specific discrimination and photoswitchable bacterial imaging for S. aureus.