Rapid screening of the hydrogen bonding strength of radicals by electrochemiluminescent probes

Photoinduced Clusteroluminescence Redshift of Poly(methyl acrylate) via Radicals

One-step photopolymerization and photochromism of clusteroluminescence (CL) polymers mean that the polymer materials can be prepared on a large scale and applied widely. Herein, we reported unique photochromic CL polymers prepared by one-step radical photopolymerization. Seven copolymerized films (PMA_xBA) with methyl acrylate and butyl acrylate as monomers, a cross-linked PMA (PMA-CL) film, a double-network PMAPBA film based on the first network PMA-CL, and four PMA films with increasing content of photoinitiator ethoxy benzoin (BEE) were prepared to study CL formation and transition. Experimental results prove that increasing the ratio of the PMA chains in PMA_xBA enhances the photochromic effect, which verifies the main role of PMA chains with the shorter branched alkanes. Surprisingly, cross-linking in PMA-CL strengthens interchain packing and interchain through-space interactions (TSIs), leading to the formation of larger clusters and further CL redshift from 410 to 491 nm, whereas the PBA chains filled in the cross-linked network weakens interchain TSIs among PMA chains and makes CL red shift from 410 to 472 nm. In addition, as the BEE content increases in the PMA films, a higher radical concentration also promotes the formation of TSIs and clusters, which benefits the photochromism. For applications, colorless, dissolvable, and thermoplastic PMA featuring photochromism in this case can be widely used in information loading, rewriting, and multifunctional coating. This work provides a new strategy to enrich the properties of CL polymers toward diverse applications.

Chaotropic Effect Stabilized Radical-Containing Supramolecular Organic Frameworks for Photothermal Therapy

Radical-containing frameworks (RCFs) have emerged as promising functional materials in various fields due to the combination of the highly ordered frame structure and the fascinating property of organic radicals. Here, the first example of radical-containing supramolecular organic frameworks (SOFs) fabricated by the chaotropic effect between closo-dodecaborate cluster (B₁₂ H₁₂^2- ) and 2,4,6-tri(4-pyridyl)-1,3,5-triazine (TPT³⁺ ) is presented. The SOFs can be easily synthesized by stirring the B₁₂ H₁₂^2- and the TPT³⁺ in aqueous solution through self-assembly. Upon 435 nm light irradiation, the SOFs exhibits photochromic behavior from slight yellow (SOF-1) to dark purple (SOF-2). Electron paramagnetic resonance spectroscopy also reveals that stable radicals are generated in situ after light irradiation. Powder X-ray diffraction demonstrates the SOFs maintain their structural stabilities upon light irradiation. More interestingly, the radical-containing SOFs exhibit efficient photothermal effect under 660 nm light irradiation, which can be applied as photothermal agent for antibacterial application both in vitro and in vivo. This work highlights the construction of RCFs through supramolecular self-assembly, which may arouse applications in energy, catalysis, photoluminescence, and biomedical fields.

Sensitive immunosensor based on high effective resonance energy transfer of lucigenin to the cathodic electrochemiluminescence of tris(bipyridine) Ru(II) complex

Electrochemiluminescence resonance energy transfer (ECL-RET) has been attracting much focus as an effective approach for great ECL enhancement. Here, we found that lucigenin (Luc) could serve as a new energy transfer donor and greatly improve the cathodic ECL of bis(2,2'-bipyridyl)(4'-methyl-[2,2']bipyridinyl-4-carboxylicacid) ruthenium(II) (Ru(Bpy)₂(Mcbpy)²⁺, acceptor). Then, both Luc and Ru(Bpy)₂(Mcbpy)²⁺ were largely co-immobilized onto the PdCu nanocrystals and polyethyleneimine (PEI) modified single-walled carbon nanohorns (SWCNHs-PdCuNCs-PEI) through π-π stacking and crosslinking reaction, respectively. By this way, the excellent electrocatalytic behavior and high loading capability for both Luc and Ru(Bpy)₂(Mcbpy)²⁺ of SWCNHs-PdCuNCs-PEI effectively facilitated the ECL reaction. Particularly, the co-immobilization strategy making the donor (Luc)/acceptor (Ru(Bpy)₂(Mcbpy)²⁺) pairs co-exist in the same nano-composite could obviously increase the ECL-RET efficiency by shortening the electron-transfer path and reducing energy loss, further significantly improving the ECL signal. Combining the obtained nano-composite (Luc-SWCNHs-PdCuNCs-PEI-Ru(Bpy)₂(Mcbpy)²⁺) with sandwiched immunoreaction, an ECL immunosensor was constructed for β2-microglobulin (β2-M) measurement. And as a result, it exhibited excellent performance in sensitivity, stability and selectivity. The establishment of the new effective donor/acceptor pairs for ECL-RET and the co-immobilization strategy of making those donor/acceptor pairs largely co-exist in the same nano-composite would greatly improve the ECL efficiency and motivate the wider application of ECL technology.

MnOx MFs as a coreaction accelerator for the construction of a novel ternary electrochemiluminescence system: ultrasensitive detection of microRNA

By using multivalent manganese oxides microflowers (MnOx MFs) as prominent a coreaction accelerator in luminol/dissolved oxygen system, and by combining these with DNA nanostructures for efficient immobilization of the electrochemiluminescence (ECL) quencher doxorubicin-ferrocenecarboxylic acid (Dox-FcCOOH), an ultrasensitive biosensing platform was constructed to conduct a microRNA assay in tumour cells.