Titanium-Based Nanoscale Metal–Organic Framework for Type I Photodynamic Therapy

Abstract

Nanoscale metal−organic frameworks (nMOFs) have shown great potential as nanophotosensitizers for photodynamic therapy (PDT) owing to their high photosensitizer loadings, facile diffusion of reactive oxygen species (ROSs) through their porous structures, and intrinsic biodegradability. The exploration of nMOFs in PDT, however, remains limited to an oxygen-dependent type II mechanism. Here we report the design of a new nMOF, Ti-TBP, composed of Ti-oxo chain secondary building units (SBUs) and photosensitizing 5,10,15,20-tetra(p-benzoato)porphyrin (TBP) ligands, for hypoxia-tolerant type I PDT. Upon light irradiation, Ti-TBP not only sensitizes singlet oxygen production, but also transfers electrons from excited TBP* species to Ti 4+based SBUs to afford TBP •+ ligands and Ti 3+ centers, thus propagating the generation of superoxide, hydrogen peroxide, and hydroxyl radicals. By generating four distinct ROSs, Ti-TBP-mediated PDT elicits superb anticancer efficacy with >98% tumor regression and 60% cure rate. Communication pubs.acs.org/JACS

Nanoscale Metal‐Organic Frameworks: Synthesis, Biocompatibility, Imaging Applications, and Thermal and Dynamic Therapy of Tumors

“…Recently, another new idea was put forward by them once again to overcome this tumor hypoxia. They designed a Ti‐TBP NMOFs, which was composed of TiCl 4 ·2THF and TBP ligands, to achieve the type I PDT with high hypoxia tolerance . The synthesized NMOFs could not only produce singlet oxygen, but also generate other three tumor killing ROS for getting a more effective treatment.…”

Synthesis of an Interrupted AST‐Type Zeolitic Imidazolate Framework

“…As the subclass of metal‐organic frameworks (MOFs), zeolitic imdazolate frameworks (ZIFs) with high surface area and exceptional stability have exhibited widely potential applications in gas storage, separation, catalysis, electrocatalysis, and so on . In their structures, metal ions ( e.g ., Zn 2+ , Co 2+ , Cd 2+ , etc .)…”

A Titanium(IV)‐Based Metal–Organic Framework Featuring Defect‐Rich Ti‐O Sheets as an Oxidative Desulfurization Catalyst

“…[1][2][3][4] However,d eveloping chemically and thermally robust materials remains challenging.This has fueled interest in using oxophilic Group 4e lements such as Zr IV and Ti IV , which tend to form stable structures based on their strong metal-carboxylate bonds.Inthis context, numerous Zr MOFs have been reported, [5] but only 15 Ti IV MOFs have been described to date,ofwhich 5inthe past year, even though Ti precursors are cheap,n on-toxic,a nd Ti MOFs tend to show good redox activity and photoactivity. [6][7][8] Them uch higher tendency of Ti IV to form ill-defined oxyhydroxides lies at the basis of this discrepancyand makes the synthesis of Ti MOFs extremely challenging. [9,10] Themajority of the Ti MOFs reported to date contain Ti À Oclusters as secondary building unit (SBU), but very recently afew chain-based Ti MOFs were reported:DGIST-1, Ti-TBP, and MIL-177-HT.…”

“…[9,10] Themajority of the Ti MOFs reported to date contain Ti À Oclusters as secondary building unit (SBU), but very recently afew chain-based Ti MOFs were reported:DGIST-1, Ti-TBP, and MIL-177-HT. [7,11,12] Thed imensionality of the SBU greatly influences MOF properties,a swas exemplified by photoconductivity measurements on the chain-based MIL-177-HT and its cluster-based counterpart, MIL-177-LT. The latter showed negligible conductivity whereas MIL-177-HT features similar conductivity as nano-sized TiO 2 ,w hich demonstrates the benefit of increasing the SBU dimensionality to achieve bulk oxide properties.Herein, we report an ew,p hotoactive,T i IV 4,4'-biphenyldicarboxylate (bpdc 2À )M OF,t ermed COK-47, featuring ac omplex layer of TiO 6 octahedra as 2D SBU.I nterestingly, acareful choice of synthetic conditions allows for control over particle morphology and defect content, making COK-47 S (S = small particle) ah ighly active catalyst, for example towards the oxidation of dibenzothiophene.S everal isoreticular analogues with for instance terephthalate or 2,2'-bipyridine-5,5'-dicarboxylate linkers were also synthesized (Supporting Information, Figure S1).…”

“…[9,10] Themajority of the Ti MOFs reported to date contain Ti À Oclusters as secondary building unit (SBU), but very recently afew chain-based Ti MOFs were reported:DGIST-1, Ti-TBP, and MIL-177-HT. [7,11,12] Thed imensionality of the SBU greatly influences MOF properties,a swas exemplified by photoconductivity measurements on the chain-based MIL-177-HT and its cluster-based counterpart, MIL-177-LT. The latter showed negligible conductivity whereas MIL-177-HT features similar conductivity as nano-sized TiO 2 ,w hich demonstrates the benefit of increasing the SBU dimensionality to achieve bulk oxide properties.…”