Dual-emission carbonized polymer dots for ratiometric sensing and imaging of L-lysine and pH in live cell and zebrafish

It is highly desired to accurately and selectively detect and image intracellular L-lysine and pH in biological systems because they could act as the biomarkers in certain abnormal conditions and may give us a warning of the occurrence of diseases.It has been attracted more focuses to design new ratiometric fluorescent probe for monitoring L-lysine and pH to improve detection accuracy.Carbonized polymer dots(CPDs),which possess carbon/polymer hybrid structure rather than pure carbon structure and constitute of a carbon core and large amounts of functional groups/polymer chains on the surface,rise up as a new type of fluorescent nanomaterials and especially display many advantages for bioanalysis.In this study,o-phenylenediamine(o-PD)and poly(styrene-co-maleic anhydride)(PSMA)are used as the precursors to synthesize the desired CPDs through one-step hydrothermal amide method.The prepared CPDs display two well-resolved fluorescence emission bands,i.e.,a very weak emission centered at 470 nm in blue region and a strong emission centered at 558 nm in yellow region.It is found that the two emissions are both responsive to L-lysine based on the surface passivation mechanism,whereas,only the yellow emission is responsive to pH due to the protonation/deprotonation process of the amino groups.Based on the different responsive behaviors,ratiometric detection and imaging of L-lysine and pH are achieved.The prepared ratiometric CPDs probe is successfully applied for L-lysine and pH sensing and imaging at two emission channels in live cell and zebrafish with satisfactory results.

Dual-Emission Carbonized Polymer Dots Combined with Metal Ions as a Single-Component Fluorescence Sensor Array for Pattern Recognition of Glycosaminoglycans

Herein,a novel dual-emission fluorescence sensor array of carbonized polymer dots(CPDs)-Cu^(2+)has been proposed,in which CPDs were prepared by one-pot hydrothermal method and Cu^(2+)acting as a quencher was combined with CPDs by electrostatic interaction.Four negatively charged glycosaminoglycans(GAGs)bearing different hydrophilic groups showed variable binding affinities towards CPDs-Cu^(2+).Upon reacting with these GAGs,the different fluorescence response signals of CPDs-Cu^(2+)can be further differentiated by principal component analysis(PCA).The CPDs-Cu^(2+)sensor array,not only allows the identification of four similarly structured GAGs,but also realizes the discrimination of different concentrations of the same GAGs and their mixtures.Remarkably,the identification of GAGs in biological fluids can also be achieved using our proposed single-component sensor array,validating its application potential.This new strategy avoids multiple sensing probes,broadens the application of tongue-mimic sensor arrays and provides a viable idea for the development of single component sensing platforms.

Small-molecule based thermally activated delayed fluorescence materials with dual-emission characteristics

Organic thermally activated delayed fluorescence(TADF)emitters have attracted increasing concerns,owing to their atypical photophysical features that can pave the way to the innovative engineering applications.As cutting-edge type of luminescent molecules,however,most of them only exert a single-wavelength emission from the lowest excited state,according to Kasha’s rule.To develop their potential applications in multicolor luminescence and multi-functional luminescent probes for biological imaging,researchers have begun to turn their attention to design organic TADF molecules with dual-emission characteristics,by employing an additional fluorescence,phosphorescence,or TADF signal within a single-component system.We herein summarized the design principles as well as the luminescence mechanism of organic donor-acceptor TADF compounds with dual-emission characteristics,the superiority of which can cover unique material applications in modern luminescencerelated fields.

Development of photoluminescence metal-organic framework sensors consisting of dual-emission centers

Incorporation of luminescent moieties into metal-organic frameworks（MOFs） has resulted in numerous photoluminescence（PL） sensors based on chromophore-analyte interactions. However, most of them are only highly sensitive to few analytes limited by the single luminescent centers in MOFs. To improve the application scopes, dual-emission MOFs were therefore emerged, which can significantly improve the sensitivity by monitoring the relative emission intensity of two luminescent centers. This short review will highlight the recent progress on dual-emission MOFs as highly sensitive sensors for probing of volatile organic molecules（VOMs）, picric acid and peroxynitrite, and as self-calibration PL thermometer.

Red/orange dual-emissive carbon dots for pH sensing and cell imaging

The dual-emissive N,S co-doped carbon dots (N,S-CDs) with a long emission wavelength were synthesized via solvothermal method.The N,S-CDs possess relatively high photoluminescence (PL) quantum yield (QY) (35.7%) towards near-infrared fluorescent peak up to 648 nm.With the advanced characterization techniques including X-ray photoelectron spectroscopy (XPS),Fourier transform infrared spectroscopy (FTIR),etc.It is found that the doped N,S elements play an important role in the formation of high QY CDs.The N,S-CDs exist distinct pH-sensitive feature with reversible fluorescence in a good linear relationship with pH values in the range of 1.0-13.0.What is more,N,S-CDs can be used as an ultrasensitive Ag+ probe sensor with the resolution up to 0.4 μM.This finding will expand the application of as prepared N,S-CDs in sensing and environmental fields.