Emission or scattering?Discriminating the origin of responsiveness in AIEgen-doped smart polymers using the TPE dye

Aggregation-induced emission(AIE)luminogens are attractive dyes to probe poly-mer properties that depend on changes in chain mobility and free volume.When embedded in polymers the restriction of intramolecular motion(RIM)can lead to their photoluminescence quantum yield(PLQY)strong enhancement if local microviscosity increases(lowering of chain mobility and free volume).Nonethe-less,measuring PLQY during stimuli,i.e.heat or mechanical stress,is technically challenging;thus,emission intensity is commonly used instead,assuming its direct correlation with the PLQY.Here,by usingfluorescence lifetime as an absolutefluorescence parameter,it is demonstrated that this assumption can be invalid in many commonly encountered conditions.To this aim,different poly-mers are loaded with tetraphenylenethylene(TPE)and characterized during the application of thermal and mechanical stress and physical aging.Under these con-ditions,polymer matrix transparency variation is observed,possibly due to local changes in refractive index and to the formation of microfractures.By combin-ing different characterization techniques,it is proved that scattering can affect the apparent emission intensity,while lifetime measurements can be used to ascertain whether the observed phenomenon is due to modifications of the photophysi-cal properties of AIE dyes(RIM effect)or to alterations in the matrix optical properties.

An overview on AIEgen-decorated porphyrins:Current status and applications

One of the major obstacles of porphyrins is the aggregation-caused quenching(ACQ)of photoluminescence due to the strong intermolecularπ–πinteraction of the planar porphyrin core in the solid state.However,ACQ leads to the nonradiative deactivation of the photoexcited states which results in short-lived charge-separated states and thus low photoluminescence and singlet quantum yields.This phenomenon would limit the utilization of porphyrins in near-infrared fluorescent bioimaging,photodynamic therapy,photocatalytic hydrogen evolution,electrochemiluminescence,and chiroptical applications.Hence,to address the ACQ property of porphyrins and enhance the performance of the above applications,a limited number of AIEgen-decorated porphyrins have been designed,synthesized,and tested for their applications.It has been found that the introduction of AIEgens,such as tetraphenylethylene,diphenylacrylonitrile,(3,6-bis-(1-methyl-4-vinylpyridinium)-carbazole diiodide,and iridium motif into the porphyrin core,transformed the porphyrins from ACQ to aggregation-induced emission(AIE)in their solid state due to the reduced strong intermolecularπ–πstacking of porphyrins.Consequently,such porphyrins containing AIE features are employed as potential candidates in the above-mentioned applications.In this review,we summarize the AIEgen-decorated porphyrins which have been published to date,and also discuss the benefits of converting porphyrins from ACQ to AIE for enhanced performance within each application.As far as we know,there is no review that summarizes the structures and applications of AIEgen-decorated porphyrins to date.Therefore,we presume that this review would be helpful to design more efficient AIEgen-decorated porphyrins for a wide range of applications in the future.

基于近红外聚集诱导发光分子的磁性纳米材料用于光增强杀菌

近红外光敏剂由于荧光成像具有光损伤小、穿透力强和空间分辨率高等优点,能显著提高光动力治疗效果。我们合成了近红外聚集诱导探针5,6-2(4′-(二苯氨酚)-[1,1′-联苯]-4-yl)吡嗪-2,3-二甲腈(DCDPP-2TPA)用于光增强杀菌。利用聚集态/固态下荧光增强的优势,DCDPP-2TPA与磁性Fe_(3)O_(4)纳米材料复合,产生更高活性氧(ROS)用于杀菌。利用SEM、TEM、XRD和荧光光谱研究了该复合材料的结构和性质,并用于大肠杆菌和金黄色葡萄球菌杀菌实验。结果表明,在光照下两种细菌的存活率为7.5%与9.0%,优于DCDPP-2TPA(10%与14%)。同时该复合材料可以方便地实现磁性分离,在光照下产生ROS后循环杀菌。

An AIEgen/graphene oxide nanocomposite(AIEgen@GO)-based two-stage“turn-on”nucleic acid biosensor for rapid detection of SARS-CoV-2 viral sequence

The ongoing outbreak of Severe Acute Respiratory Syndrome Coronavirus 2(SARS-CoV-2)pandemic has posed significant challenges in early viral diagnosis.Hence,it is urgently desirable to develop a rapid,inexpensive,and sensitive method to aid point-of-care SARS-CoV-2 detection.In this work,we report a highly sequence-specific biosensor based on nanocomposites with aggregationinduced emission luminogens(AIEgen)-labeled oligonucleotide probes on graphene oxide nanosheets(AIEgen@GO)for one step-detection of SARS-CoV-2-specific nucleic acid sequences(Orf1ab or N genes).A dual“turn-on”mechanism based on AIEgen@GO was established for viral nucleic acids detection.Here,the first-stage fluorescence recovery was due to dissociation of the AIEgen from GO surface in the presence of target viral nucleic acid,and the second-stage enhancement of AIEbased fluorescent signal was due to the formation of a nucleic acid duplex to restrict the intramolecular rotation of the AIEgen.Furthermore,the feasibility of our platform for diagnostic application was demonstrated by detecting SARS-CoV-2 virus plasmids containing both Orf1ab and N genes with rapid detection around 1 h and good sensitivity at pM level without amplification.Our platform shows great promise in assisting the initial rapid detection of the SARS-CoV-2 nucleic acid sequence before utilizing quantitative reverse transcription-polymerase chain reaction for second confirmation.