Hollow Spherical Covalent Organic Frameworks from Nonplanar or Planar Monomers for the Fluorescence Detection of Telomere DNA: Role of the 2-(2-Azidoethoxy)ethoxy Group

Abstract

Construction of covalent organic frameworks (COFs) with a hollow and uniform morphologyregardless of whether planar or nonplanar building blocks are employedis still challenging. Herein, we report a facile strategy for the self-assembly and template-free synthesis of hollow spherical COFs by increasing the percentage content of 2-(2-azidoethoxy)ethoxy groups in the pore skeleton of a COF. Moreover, the morphological diversity dependent on the percentage content of 2-(2-azidoethoxy)ethoxy groups in the COF structure is observed. COF-100%N3, which is formed by the polycondensation of the nonplanar 1,3,5-tris(4-aminophenyl)benzene monomer, having the highest percentage content of the 2-(2-azidoethoxy)ethoxy group (100%), is self-assembled into homogeneous hollow spheres. For the first time, our strategy effectively explores the self-assembly of the planar monomer into a hollow spherical COF. Hollow spherical TPP-COF-100%N3 is formed via the polycondensation of the planar 2,4,6-tris(4-aminophenyl)pyridine monomer and 2-(2-azidoethoxy)ethoxy group (100%). Due to the favorable characteristics of its specific surface area and hollow mesoporous nature, spherical COF-100%N3 functions as an enticing sensing platform for the fluorescence-selective and -sensitive detection of telomere DNA. Consequently, this research study documents a facile strategy for constructing a unique hollow spherical COF and expands the application of COFs as fluorescent platforms for DNA detection.

Side-Chain-Assisted Transition of Conjugated Polymers from a Semiconductor to Conductor and Comparison of Their NO2 Sensing Characteristics

“…Interestingly, although both CPs exhibited bimodal-shaped absorption spectra commonly seen in D-A type CPs [ 43 , 44 ], the absorption in the film state was found to be more red-shifted than that in the solution state, only in the longer wavelength region. This can be attributed to facile intramolecular CT interactions between D-A moieties via partial chain planarization or enhanced non-covalent interactions of CP chains in the film state [ 45 ]. When the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of each CP were identified using AC2 and the absorption edge, both CPs were confirmed to have similar molecular energy levels with an extremely narrow band-gap of 0.9 eV ( Figure 1 c).…”

Nanoarchitectonics of Hollow Covalent Organic Frameworks: Synthesis and Applications

“…For example, by integrating various imaging agents and delivery cargoes, it is possible to achieve multiple functions, such as the combination of optical imaging and drug delivery . In another example, EL-Mahdy et al investigated the self-assembly of planar organic monomers to form a hollow spherical COF that served as a promising sensing platform for the fluorescence detection of telomere DNA with high selectivity and sensitivity . To further enhance the ability of these materials in the medical field, efforts should be made to develop more controllable drug release systems that can be activated by various external or internal stimuli, such as pH, temperature, light, etc.…”

“…Attributed to their high chemical stability, absence of metal ions, large specific surface area, and well-confined hollow structure, hollow COFs have incomparable advantages, including high loading ability, controllable release, and good biocompatibility. , Hollow COFs are a kind of valuable alternative material in biomedical applications. To date, several hollow COF materials have been fabricated and utilized for biomedical applications, such as drug delivery, ,, therapy, ,, in vivo imaging, and fluorescence sensing …”

“…To date, several hollow COF materials have been fabricated and utilized for biomedical applications, such as drug delivery, 20,31,73 therapy, 34,42,112 in vivo imaging, 40 and fluorescence sensing. 113 In a study conducted by Banerjee et al, hollow spherical COFs were synthesized, and their potential as drug delivery vehicles were evaluated. 20 The results revealed that the resulting hollow COFs exhibited a high drug loading capacity (0.35 mg g −1 ) for the anticancer drug doxorubicin.…”

π-Electron-Extended Triazine-Based Covalent Organic Framework as Photocatalyst for Organic Pollution Degradation and H2 Production from Water

“…The majority of these COFs demonstrated significant characteristics. Then, they excelled in a variety of uses in gas uptaking, energy storage, poisonous metal ion sensing and removing, detecting, photocatalysis, optical devices, and solar energy [ 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 ]. Additionally, COFs are desirable substances for the adsorptive and photocatalytic degradation of natural dyes in aqueous media due to their significant absorption activities and extensive conjugation [ 55 , 56 , 57 ].…”