Engineering of Reversible Luminescent Probes for Real-Time Intravital Imaging of Liver Injury and Repair

As the major organ for drug metabolism and detoxification,the liver is prone to damage and severely impaired functionality.The treatment of liver diseases is based on a clear understanding of the process underlying liver injury and repair.However,intravital real-time imaging of liver injury and repair is still limited due to the lack of in vivo reversible visualization methods.To this end,we proposed a rational design strategy for the development of a reversible upconversion luminescence nanoprobe that allows real-time and in vivo imaging of liver injury and repair processes.As a proof of concept,we first developed a small molecule probe NB3 which can reversibly respond to related analytes of early liver injury[peroxynitrite(ONOO−)]and liver repair[glutathione(GSH)].The small molecule probe was then integrated with a core–shell upconversion nanoparticle to form a sophisticated nanoprobe.Compared with traditional small molecule probes,this nanoprobe exhibited a higher selectivity to ONOO−,longer retention time in liver,and wider dynamic response range to GSH after oxidation by ONOO−.The novel nanoprobe facilitated the successful monitoring and discrimination among the different degrees of liver injury and repair in a mouse model.

HEDP-capped Terbium Orthophosphate Nanoparticles as Sensitive Luminescent Probes for the Detection of Pb2＋ Ions

Terbium orthophosphate nanoparticles were synthesized using 1-hydroxy ethylidene-l,l-diphosphonic acid（HEDP） as a capping ligand under hydrothermal conditions at 80 ℃. These HEDP-capped TbPO4 nanoparticles owned a hexagonal phase structure according to the powder X-ray diffraction（XRD） results and were spherical monodispersed particles with a diameter of about 10 nm confirmed by transimission electron microscope（TEM） images. Interestingly, the luminescent intensities of the HEDP-capped TbPO4 nanoparticles decreased obviously in the presence of Pb2＋ ions and such a quenching behavior of luminescence was well fitted by the Stern-Volmer equation.

Synthesis and Structural Investigation of （LaO）_3BO_3 with Eu^（3＋） as Luminescent Probe

Europium (Eu￣(3+)) doped polycrystalline (LaO)_3BO_3 has been synthesized by solid state reaction with Li_2CO_3 as flux at 1200℃ for 10 h in air. X- ray powder diffraction shows that ( LaO)_3BO_3 crystallizes in a monoclinic cell [a= 0. 69214 (9)nm , b=1. 2929(3) nm , c=1. 4590 (3 ) nm . β= 99. 35 (2)°,V= 1. 2882(4 ) nm￣3 and Z= 8] with a possible space group of P2_1/m or P2_1. The predominance of electric-dipole transition ￣5D_0→ ￣7F_2 in the fluorescence spectrum , as well as the splitting of the￣7F_j ground states of Eu￣(3+) reveals that the lanthanum atoms distribute in the sites with C_1 or C_s symmetry in this structure.

Luminescent probes for luminescence lifetime sensing and imaging in live cells:a narrative review

Luminescence(mostly fluorescence and phosphorescence)probes are a powerful tool widely used in the life sciences research.They can be used,for example,in the quantitative analysis of physiological parameters,visualization of different cell organelles,and measurement of drug transportation.The luminescence intensity and lifetime of these probes are among the main signals recorded and evaluated in these applications.Other reviews have discussed optical probes from the perspective of their luminescence intensity.However,the luminescence lifetime,which depends on the molecular microenvironment but not the probe concentration,is another promising metric for biological sensing and imaging applications.In this review,we aim to introduce the basic strategies of FLIM probe design.We also present applications of these probes,including sensing of intracellular pH,cation/anion concentrations,oxygen levels,biomolecule contents,and physiological parameters,as well as live-cell imaging based on luminescence lifetime.Studies based on FLIM imaging of cells or tissues with endogenous organic molecules are not included in this mini review.With the rapid development of microscopy technology for fluorescence lifetime imaging,fluorescence lifetime-based probes have shown great potential in a variety of biological applications.

Studies on Plant Calmodulin and Its Interaction with Antagonist W_7 by Ln^(3+) Luminescence Probes

Plant calmodulin(CaM) has been extracted from cauliflower, and the purified CaM has been identified with the activation of NAD kinase(NADK) and the inhibition effect of CaM antagonist W 7. CaM′s intrinsic fluorescence and Tb 3+ fluorescence showed that there was one tyrosine residue and four metal binding sites in cauliflower CaM. Based on Frster type nonradiative energy theory, the distances of Tyr→site Ⅲ, Ⅳ have been determined , and these are 1 23 nm(Tyr→site Ⅲ) and 1 18 nm(Tyr→site Ⅳ). The Eu 3+ and Tb 3+ fluorescence probes showed that the combination of CaM with W 7 resulted in significant change on CaM′s conformation, but did not affect coordination environment of metal binding sites.

Recent progress on lanthanide complexes/clay minerals hybrid luminescent materials

The unique luminescent performance of lanthanide complexes/clay minerals hybrid materials has been fascinating many researchers for recent decades.It not only retains the excellent luminescent characteristics of lanthanide complexes but also improves the poor stability of the complexes.In this article,we introduce the luminescence mechanism of lanthanide complexes and point out the necessity of their combination with clay minerals.After the analysis of the structure and interlayer environment differences of 1:1-type and 2:1-type clay minerals,the intercalation methods(covalent grafting and ion exchange)appropriate for different clay minerals are summarized with examples.Based on the luminescence characteristics of the hybrid materials,the applications of these materials as luminescent probes in recognition of specific metal cations and molecules,detection of pH value,and temperature are reviewed.Finally,the current problems in the preparation of lanthanide complexes/clay minerals hybrid luminescent materials and shortcomings that need improvement in their performance are analyzed,and the application prospect is forecast.

Positive Luminescent Sensor for Aerobic Conditions Based on Polyhedral Oligomeric Silsesquioxane Networks

There are numerous numbers of hypoxia-selective luminescent probes based on oxygen quenching of phosphorescence.We show a unique design for luminescent probes to detect hyperoxia utilizing hybrid networks consisting of aggregation-induced emission(AIE)-active dyes and disulfide linkers.At the initial state,emission from the AIE-active dyes is inducible by suppressing energy-consumable intramolecular motions in the hybrid matrices,while the decrease in intensity was detected by releasing molecular motions corresponded to bond scission at the disulfide linkers.Particularly,it was shown that this process selectively proceeds in hypoxia.As a result,positive luminescent signals were obtained in hyperoxia.

Observing antimicrobial process with traceable gold nanodusters

Understanding the interaction of nanomaterials with biological systems has always been of high concern and interest.An emerging type of nanomaterials,ultrasmall metal nanoclusters(NCs,<2 nm in size),are promising in this aspect due to their well-defined molecular formulae and structures,as well as unique physical and chemical properties that are distinctly different from their larger counterparts(metal nanoparticles).For example,metal NCs possess intrinsic strong luminescence,which can be used for real-time tracking of their interactions with biological systems.Herein,luminescent gold(Au)NCs were used as traceable antimicrobial agents to study their interactions with the bacteria and tofurther understand their underlining antimicrobial mechanism.It is shown for the first time that the Au NCs would first attach on the bacterial membrane,penetrate,and subsequently accumulate inside the bacteria.Thereafter,the internalized Au NCs would induce reactive oxygen species(ROS)generation and damage the bacterial membrane,resulting in the leakage of bacterial contents,which can finally kill the bacteria.Traceable Au NCs(or other metal NCs)provide a promising platform to study the antimicrobial mechanisms as well as other fundamentals on the interfacing of functional nanomaterials with the biological systems,further increasing their acceptance in various biomedical applications.

Synthesis of a di(2-picolyl)amino-b-diketone dual-functional ligand that can coordinate to europium(Ⅲ) for responding to copper(Ⅱ) and sulfide ions

Lanthanide complex-based luminescent probes/chemosensors have shown great utilities in various biological and environmental assays with time-resolved detection mode to eliminate background noises.In this work,by conjugating di（2-picolyl）amine（DPA）with a tetradentateβ-diketone 1,2-bis[4＇-（1＂,1＂,1＂,2＂,2＂-pentafluoro-3＂,5＂-pentanedion-5＂-yl）benzyl]-4-chlorosulfo-benzene（BPPBCB）,a novel dual-functional ligand that can coordinate to Eu^（3＋）for responding to Cu^（2＋）and S^2 ions in aqueous media,DPA-BPPBCB,has been designed and synthesized.Theβ-diketone moiety of DPA-BPPBCB can form a strongly luminescent complex with Eu^（3＋）.Upon reaction with Cu^（2＋）,accompanied by the formation of heterobimetallic complex Cu^（2＋）-DPA-BPPBCB-Eu^（3＋）,the Eu^（3＋）luminescence was quenched.While in the presence of S^2,owing to the high affinity of S^2 to Cu^（2＋）,stable CuS was formed,which resulted in the release of Cu^（2＋）from Cu^（2＋）-DPA-BPPBCB-Eu^（3＋）,to restore the luminescence of the Eu^（3＋）complex.This unique＂on-off-on＂luminescence response of the Eu3＋complex enabled Cu^（2＋）and S^2 ions in aqueous media to be detected with time-resolved luminescence detection mode.