Targeted Photodynamic Therapy with a Folate/Sensitizer Assembly Produced from Mesoporous Silica

Abstract

A mesoporous silica material prepared by using folic acid (FA) as a template enables the effective encapsulation of meso-tetrakis(4-carboxyphenyl)porphyrin (TCPP) in its interior. Combination of steady-state and time-resolved absorption and emission spectroscopy demonstrate that FA and TCPP are released from the silica material to the aqueous phase in the form of a non-covalent assembly. This assembly does not form by simple mixing of the two components in the absence of silica, suggesting the key role of the material in the assembling process. The FA/TCPP assembly exhibits dual color fluorescence in the visible region, good photosensitization capability of singlet oxygen, and enhanced photo-induced mortality in KB cancer cells overexpressing folate receptor, if compared with the free components.

Photochemistry and Photophysics in Silica-Based Materials: Ultrafast and Single Molecule Spectroscopy Observation

“…Finally, mesoporous SBMs can be used both as drug nanocarriers and as “reactors” for the noncovalent assembly of synergetic entities (Figure ). The first such example of noncovalent assembly between FA and a porphyrin [tetrakis­(4-carboxyphenyl)­porphyrin, TCPP] in mesoporous silica particles has been reported recently . The assembly process does not occur in aqueous solutions but occurs exclusively in the interior of the mesoporous silica material that entraps both components.…”

“…The assembly shows enhanced and preserved fluorescence in the FA and TCPP spectral regions, respectively, along with the ability to photosensitize the formation of singlet oxygen slightly better than the free photosystem can. The assembly has demonstrated high potential for the photoinactivation of KB cancer cells over expressing the folate receptors, compared with the potential of free TCPP, most likely because of the FA targeting effect …”

“…Schematic representation showing the concept of PDT using FA/TCPP assembly released from mesoporous silica material to kill cancer cells. Reprinted with permission from ref . Copyright 2017 Wiley-VCH.…”

Alkane Chain‐extended Pterin Through a Pendent Carboxylic Acid Acts as Triple Functioning Fluorophore, 1O2 Sensitizer and Membrane Binder

“…Over the past 6–8 years, “smart” compounds that possess dual fluorescence sensing and singlet oxygen sensitizing properties have become a hot topic , with success reported in dual function image‐guided and photodynamic therapy applications (PDT) . Indeed, our previous O ‐ and N ‐decyl‐pterins possessed good singlet oxygen quantum yields (Φ ∆ ), but had poor fluorescence quantum yields (Φ F ) some 4–30 fold less compared to native pterin, thereby fulfilling only two of three facets, even though a minor fluorescence increase was observed when intercalated in the membrane .…”

Assessing Photosensitizer Targeting Using Meso-Tetra(Carboxyphenyl) Porphyrin

“…As such, functionalization immediately provides multivalency, which has been demonstrated to improve targeting specificity [ 30 ]. mTCPP has been used in numerous applications including porphyrin metal organic frameworks [ 31 ], mesoporous silica [ 32 ], polymeric injectable theranostic probes [ 33 , 34 , 35 ], and polymeric implantable biosensors [ 36 , 37 , 38 ]. A structurally similar meso-tetra(4-hydoxylphenyl) porphyrin was used for functionalization and attachment of gadolinium chelates to produce a theranostic agent [ 39 ].…”