A Sensitive and Selective Ratiometric Near IR Fluorescent Probe for Zinc Ions Based on the Distyryl−Bodipy Fluorophore

A Sensitive Probe of Meso-Cyanophenyl Substituted BODIPY Derivative as Fluorescent Chemosensor for the Detection of Multiple Heavy Metal Ions

A fluorescent turn-on chemosensor (BA) was constructed by attaching bis(pyridin-2-ylmethyl)-amine (DPA) unit to the BODIPY scaffold. It can give a prominent green/yellow fluorescent response selectivity with each of Zn2+/Hg2+/Cd2+/Ca2+/Mn2+/Pb2+/Al3+. The 1:1 stoichiometry of BA and metal ions was drawn from the analysis of Job's plot. The limit detection of BA in recognition of Zn2+/Hg2+/Cd2+/Ca2+/Mn2+/Pb2+/Al3+ is ranged in 50.8-146.6 nM. There exists a linear relationship between the fluorescence intensity and concentration of metal ions (Zn2+: 4-15 µM). The mechanism of fluorescence signal "turn-on" is based on the photo induced transfer (PET) in the excited state of BA. The coordinated metal ions significantly weakened the electron-donating ability nitrogen atom in DPA, thus recovering the emission character of BODIPY. The substituted group at the phenyl ring in meso-position of BODIPY scaffold determines the recognizable list of metal ions.

Pyrogallol-based dipodal optical probe as new smart analytical tool for sustainable detection of cobalt in biosystem

The present research focuses on the micro-level detection of cobalt ions in biological and environmental samples using a new probe. The probe is a multifunctional symmetrical dipodal molecule with two pyrogallol binding units attached to the malonate scaffold through a propylene spacer. It was synthesized and characterized by 1H NMR, 13C NMR, IR, electronic spectroscopy, and mass spectrometry. The molecule's binding, thermodynamic, and photophysical properties are also described. The designed probe demonstrates an excellent sensing ability for Co(II) based on the ESIPT "OFF-ON" fluorescence mechanism. The experiments explore the high selectivity of the ligand for cobalt sensing over a wide range of metal ions of biological and environmental importance. The fluorescence intensity shows a linear response to Co(II) in 5-100 μM concentration with a detection limit of 8.75 x 10-5 and a 2.65-fold enhancement in the intensity. These results establish its potential application as a fluorescence sensor. The probe is also employed as a colorimetric sensor for the qualitative determination of cobalt ions in DMSO solution. The interesting behavior of the probe motivated us further to study its coordination properties with divalent cobalt in solution. The pre-organized assembly with an appropriate cavity size favors the ligand for an efficient Co(II) encapsulation by coordinating through imine-Ns and aromatic ring-Os donors, giving high formation constants.

BODIPY as a Multifunctional Theranostic Reagent in Biomedicine: Self-Assembly, Properties, and Applications

The use of boron dipyrromethene (BODIPY) in biomedicine is reviewed. To open, its synthesis and regulatory strategies are summarized, and inspiring cutting-edge work in post-functionalization strategies is highlighted. A brief overview of assembly model of BODIPY is then provided: BODIPY is introduced as a promising building block for the formation of single- and multicomponent self-assembled systems, including nanostructures suitable for aqueous environments, thereby showing the great development potential of supramolecular assembly in biomedicine applications. The frontier progress of BODIPY in biomedical application is thereafter described, supported by examples of the frontiers of biomedical applications of BODIPY-containing smart materials: it mainly involves the application of materials based on BODIPY building blocks and their assemblies in fluorescence bioimaging, photoacoustic imaging, disease treatment including photodynamic therapy, photothermal therapy, and immunotherapy. Lastly, not only the current status of the BODIPY family in the biomedical field but also the challenges worth considering are summarized. At the same time, insights into the future development prospects of biomedically applicable BODIPY are provided.

Lysosome directed red light photodynamic therapy using glycosylated iron-(III) conjugates of boron-dipyrromethene

To overcome the drawbacks associated with chemotherapeutic and porphyrin-based photodynamic therapy (PDT) agents, the use of BODIPY (boron-dipyrromethene) scaffold has gained prominence in designing a new generation of photosensitizers-cum-cellular imaging agents. However, their poor cell permeability and limited solubility in aqueous medium inhibits the in-vitro application of their organic form. This necessitates the development of metal-BODIPY conjugates with improved physiological stability and enhanced therapeutic efficacy. We have designed two iron(III)-BODIPY conjugates, [Fe(L^1/2)(L³)Cl] derived from benzyl-dipicolylamine and its glycosylated analogue along with a BODIPY-tagged catecholate. The complexes showed intense absorption bands (ε ∼ 55,000 M^-1 cm^-1) and demonstrated apoptotic PDT activity upon red-light irradiation (30 J/cm², 600-720 nm). The complex with singlet oxygen quantum yield value of ∼0.34 gave sub-micromolar IC₅₀ (half-maximal inhibitory concentration) value (∼0.08 μM) in both HeLa and H1299 cancer cells with a photocytotoxicity index value of >1200. Both the complexes were found to have significantly lower cytotoxic effects in non-cancerous HPL1D (human peripheral lung epithelial) cells. Singlet oxygen was determined to be the prime reactive oxygen species (ROS) responsible for cell damage from pUC19 DNA photo-cleavage studies, 1,3-diphenylisobenzofuran and SOSG (Singlet Oxygen Sensor Green) assays. Cellular imaging studies showed excellent fluorescence from complex 2 within 4 h, with localization in lysosomes. Significant drug accumulation into the core of 3D multicellular tumor spheroids was observed within 8 h from intense in-vitro emission. The complexes exemplify iron-based targeted PDT agents and show promising results as potential transition metal-based drugs for ROS mediated red light photocytotoxicity with low dosage requirement.

BODIPY-GO nanocomposites decorated with a biocompatible branched ethylene glycol moiety for targeted PDT

The properties of graphene oxide (GO) have received much attention and been applied to the exploration of potential applications in disease-related diagnostics and non-invasive therapy. One application, photodynamic therapy (PDT), involves the killing of cancer cells where singlet oxygen is generated with light irradiation of the appropriate wavelength. In this work, three new BODIPY derivatives (13-15), decorated with carbohydrate moieties for active targeting and branched ethylene glycol for biocompatibility, and their GO based nanocarriers were designed to study the singlet oxygen production and PDT efficiency. First, BODIPYs were prepared, followed by the fabrication of GO layers with BODIPY dyes via a non-covalent method. Detailed characterizations of the materials were carried out with mass spectrometry, FT-IR spectroscopy, ¹H NMR, ¹³C NMR, elemental analysis, Raman spectroscopies, EDX analysis and TEM and AFM microscopies. The efficiency of singlet oxygen generation in organic and water-based solutions was determined by photobleaching with 1,3-diphenylisobenzofuran (DPBF) and 9,10-anthracenediyl-bis(methylene)dimalonic acid (ABDA), respectively. The results in in vitro PDT analysis against K562 human cancer cells indicate the prepared materials are highly promising in PDT anticancer therapy and the IC₅₀ values of GO loaded BODIPY derivatives bearing heavy atoms, GO-14 and GO-15, were calculated as 40.59 nM and 39.21 nM, respectively.

A Fluorescent Turn-On Sensor Toward Multiple Heavy Metal Ions Based on Meso-anisole Modified BODIPY Scaffold

A fluorescent turn-on sensor (BOPA) was configured by anchoring bis(pyridin-2-ylmethyl)-amine (DPA) unit to the BODIPY scaffold. It exhibits highly sensitivity and selectivity towards Pb²⁺, Ba²⁺, Cr³⁺, Cd²⁺, Hg²⁺, Zn²⁺ against the competent metal ions. Job's plot analysis supports the 1:1 stoichiometry of BOPA and metal ions. And linear relationship between fluorescence intensity and concentration of Zn²⁺ (representative metal ion) was observed over the range 0 ~ 20 μM Zn²⁺. The limit detection of BOPA in recognition of Pb²⁺, Ba²⁺, Cr³⁺, Cd²⁺, Hg²⁺, Zn²⁺ was ranged from 15.99 to 43.57 nM. Photo induced transfer (PET) in the excited state of BOPA determines the emission "off/on". Coordination of metal ions by DPA significantly weakened the electron-donating ability of nitrogen atom and inhibits the PET, recovering emission of BODIPY. In addition, the attachment of anisole at meso-position of BODIPY finely modulated the recognition of metal ions category.

Tetracyanobutadiene Bridged Push-Pull Chromophores: Development of New Generation Optoelectronic Materials

This review describes the design strategies used for the synthesis of various tetracyanobutadiene bridged donor-acceptor molecular architectures by a click type [2+2] cycloaddition-retroelectrocyclization (CA-RE) reaction sequence. The photophysical and electrochemical properties of the tetracyanobutadiene bridged molecular architectures based on various moieties including diketopyrrolopyrrole, isoindigo, benzothiadiazole, pyrene, pyrazabole, truxene, boron dipyrromethene (BODIPY), phenothiazine, triphenylamine, thiazole and bisthiazole are summarized. Further, we discuss some important applications of the tetracyanobutadiene bridged derivatives in dye sensitized solar cells, bulk heterojunction solar cells and photothermal cancer therapy.

Aggregation behavior and spectroscopic properties of red-emitting distyryl-BODIPY in aqueous solution, Langmuir-Schaefer films and Pluoronic® F127 micelles

Red-emitting distyryl substituted BODIPY dyes are among the most promising luminophors for bioimaging and optics applications. However, the practical application of BODIPYs is limited due to their high hydrophobicity and tendency to aggregate in aqueous organic solutions and solid phase. In this article, we propose an elegant solution to this problem. To this end, we carried out the detailed experimental and quantum-chemical study of the structural and spectral features of BF₂-ms-phenyl-5,5'-bis(4-dimethylaminostyryl)-3,3'-dimethyl-2,2'-dipyrromethene (distyryl-BDP). The particular attention was paid to analysis of high sensitivity of the distyryl-BDP spectral characteristics to the solvent properties, and also the aggregation behavior features both in water-organic media and in mono- and multilayer Langmuir-Schaefer films. We selected the best conditions to obtain the hydrophilic micellar structures of distyryl-BDP with Pluronic® F127 having a high efficiency of dye solubilization. This method increasing the solubility improves the distyryl-BDP transport efficiency in physiological aqueous media. The aqueous solutions of distyryl-BDP-Pl micelles show the intense fluorescence in the phototherapy window region (λ_fl = 739 nm).

Activity-based NIR fluorescent probes based on the versatile hemicyanine scaffold: design strategy, biomedical applications, and outlook

The discovery of a near-infrared (NIR, 650-900 nm) fluorescent chromophore hemicyanine dye with high structural tailorability is of great significance in the field of detection, bioimaging, and medical therapeutic applications. It exhibits many outstanding advantages including absorption and emission in the NIR region, tunable spectral properties, high photostability as well as a large Stokes shift. These properties are superior to those of conventional fluorogens, such as coumarin, fluorescein, naphthalimides, rhodamine, and cyanine. Researchers have made remarkable progress in developing activity-based multifunctional fluorescent probes based on hemicyanine skeletons for monitoring vital biomolecules in living systems through the output of fluorescence/photoacoustic signals, and integration of diagnosis and treatment of diseases using chemotherapy or photothermal/photodynamic therapy or combination therapy. These achievements prompted researchers to develop more smart fluorescent probes using a hemicyanine fluorogen as a template. In this review, we begin by describing the brief history of the discovery of hemicyanine dyes, synthetic approaches, and design strategies for activity-based functional fluorescent probes. Then, many selected hemicyanine-based probes that can detect ions, small biomolecules, overexpressed enzymes and diagnostic reagents for diseases are systematically highlighted. Finally, potential drawbacks and the outlook for future investigation and clinical medicine transformation of hemicyanine-based activatable functional probes are also discussed.

BODIPY derivatives as fluorescent reporters of molecular activities in living cells

Fluorescent compounds have become indispensable tools for imaging molecular activities in the living cell. 4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) is currently one of the most popular fluorescent reporters due to its unique photophysical properties. This review provides a general survey and presents a summary of recent advances in the development of new BODIPY-based cellular biomarkers and biosensors. The review starts with the consideration of the properties of BODIPY derivatives required for their application as cellular reporters. Then review provides examples of the design of sensors for different biologically important molecules, ions, membrane potential, temperature and viscosity defining the live cell status. Special attention is payed to BODPY-based phototransformable reporters.

The bibliography includes 339 references.

Research Progress of Small Molecule Fluorescent Probes for Detecting Hypochlorite

Hypochlorous acid (HOCl) generates from the reaction between hydrogen peroxide and chloride ions via myeloperoxidase (MPO)-mediated in vivo. As very important reactive oxygen species (ROS), hypochlorous acid (HOCl)/hypochlorite (OCl⁻) play a crucial role in a variety of physiological and pathological processes. However, excessive or misplaced production of HOCl/OCl⁻ can cause variety of tissue damage and human diseases. Therefore, rapid, sensitive, and selective detection of OCl⁻ is very important. In recent years, the fluorescent probe method for detecting hypochlorous acid has been developed rapidly due to its simple operation, low toxicity, high sensitivity, and high selectivity. In this review, the progress of recently discovered fluorescent probes for the detection of hypochlorous acid was summarized with the aim to provide useful information for further design of better fluorescent probes.

A Fluorinated Carbanionic Substituent for Improving Water Solubility and Lipophilicity of Fluorescent Dyes

Installation of a carbanionic substituent, that is strongly stabilized by two (trifluoromethyl)sulfonyl (Tf=SO₂ CF₃ ) groups, into several fluorescence dyes including boron-dipyrromethenes (BODIPYs), fluoresceins, and aminocoumarins has been achieved by the 2,2-bis(triflyl)ethylation reaction of the dye frameworks with highly electrophilic Tf₂ C=CH₂ , followed by neutralization with NaHCO₃ . Despite the contradiction between water solubility and lipophilicity, the carbanion-decorated dyes thus obtained showed significant enhancement of not only water solubility but also lipophilicity. This work clearly demonstrates that the fluorinated, highly stabilized carbanionic substituent is a new option for controlling the macroscopic property of chemical materials.

A DCM-based NIR sensor for selective and sensitive detection of Zn2+ in living cells

Zinc ion is the 2nd abundant transition metal element in human's body. It is responsible for many physiological and biological functioning in the body, such as growth of people, immunity, endocrine, etc. The deficiency of zinc could result in an increasing risk for growth retardation, neurological disorder and infectious disease. Thus, developing a nondestructive method for detecting Zn²⁺ in living systems is important. Here we reported a 2-(2-methyl-4H-ylidene)- malononitrile (DCM)-based NIR probe DF-Zn for selective and sensitive detection of Zn²⁺. The probe DF-Zn is cell-permeable and stable at broad pH range. DF-Zn showed a fast response to Zn²⁺, big stock's shift, and "nude-eye" recognition for Zn²⁺. Moreover, the selective binding of probe DF-Zn to Zn²⁺ was reversible. With the addition of EDTA in buffer solution, reversible response of probe to Zn²⁺ could be observed in MCF-7 cells imaging.

Synthesis and DSSC application of BODIPY decorated triazole bridged and benzene nucleus cored conjugated dendrimers

Conjugated dendrimers decorated with 5,5-difluoro-10-(4-(prop-2-ynyloxy)phenyl)-5H-dipyrrolo[1,2-c:1',2'-f][1,3,2]diazaborinin-4-ium-5-uide, usually known as boron dipyrromethene (BODIPY), have been synthesized and their application as photosensitizer in dye sensitized solar cells (DSSCs) has been evaluated. Third generation triazole bridged BODIPY dendrimers show higher light energy harvesting efficiency of 2.5% better than the first and second generation dendrimers, when used as a dye material in solar cells. The current intensity increases with an increase in the generation of the dendrimer as revealed by cyclic voltammetry. Fluorescence decay analysis shows that the relaxation times τ ₁ and τ ₂ increase as the dendrimer generation increases, however τ ₂ for the third generation dendrimer decreases because of fluorescence quenching due to molecular crowding.

A large-Stokes-shift fluorescent probe for Zn2+ based on AIE, and application in live cell imaging

A fluorescence-enhanced sensor based on aggregation-induced emission (AIE) was synthesized using a di(2-picolyl)amine (DPA) group as a highly selective metal chelating agent for Zn²⁺. The combination of the probe and Zn²⁺ was achieved in an environment where the volume fraction of water was 90%, giving the probe good biocompatibility, and a large Stokes shift (100 nm) occurred after Zn²⁺ was combined with the probe. The obvious color change makes the probe visible to the naked eye, and gives it a high signal-to-noise ratio, and high contrast, and minimizes self-absorption. Because of the high selectivity of the DPA group to Zn²⁺, the sensitivity of the probe to detect Zn²⁺ has been improved. The mechanism of the formation of complexes between the probe and Zn²⁺ was confirmed by nuclear magnetic resonance spectroscopy (NMR), high-resolution mass spectrometry (HRMS), and particle size distribution. Under the optimal experimental conditions, the linear fluorescence reaction of Zn²⁺ was good, between 0.2 and 18 μM, and the detection limit was 1.3 × 10^-7 M. The low toxicity and excellent membrane permeability of the probe in living cells enable it to be efficiently applied for Zn²⁺ imaging in cells. Graphical abstract.

Multi-state amine sensing by electron transfers in a BODIPY probe

Photoinduced electron transfer sets up the BODIPY probe for multi-state amine sensing by single-electron transfer then collisional quenching.

Simultaneous dual-colour tracking lipid droplets and lysosomes dynamics using a fluorescent probe

After entering a cell, most small molecule fluorescent probes are dispersed in the cytoplasm before they then accumulate in a specific organelle or subcellular zone. Molecules that can enter two or more organelles with high selectivity are all but unknown. In this work, we report a naphthalimide-based fluorescent probe, NIM-7, that allows lipid droplets and lysosomes to be labelled simultaneously and with high specificity. These subcellular entities can then be visualized readily through yellow and red fluorescence, using different excitation and detection channels. NIM-7 allows 3D imaging and quantitative visualizing of lipid droplets and lysosomes. It is also able to track simultaneously the movement of lipid droplets and lysosomes in real-time. We also report here that NIM-7 can be used to image both different cell lines and zebrafish embryos.

A unique benzimidazole-naphthalene hybrid molecule for independent detection of Zn2+ and N3- ions: Experimental and theoretical investigations

Single crystal X-ray structurally characterized benzimidazole-naphthalene hybrid (NABI) functions as a unique dual analyte sensor that can detect Zn²⁺ cation and N₃^- anion independently. The NABI forms chelate with Zn²⁺ to inhibit internal charge transfer (ICT) and CHN isomerisation resulting chelation enhanced fluorescence (CHEF). On the other hand, the sensing of N₃^- is based on formation of supramolecular H-bonded rigid assembly. The association constant of NABI for Zn²⁺ and N₃^- ions are 19 × 10⁴ M^-1 and 11 × 10² M^-1, respectively. Corresponding limit of detections (LOD) are 6.85 × 10^-8 and 1.82 × 10^-7 M, respectively. NABI efficiently detects intracellular Zn²⁺ and N₃^- ions with no cytotoxicity on J774A.1cells under fluorescence microscope. DFT studies unlock underlying spectroscopic properties of free NABI and Zn²⁺/N₃^- bound forms.

Exploration research on synthesis and application of a new dye containing di-2-picolyamine

A newly designed fluorescence dye L based on di-2-picolyamine (DPA) moiety as a chelator was obtained under the protection of N₂ at 120°C, and KI as catalyst with relatively better yield. More interestingly, L not only could selectively and sensitively detect Cu²⁺ ions in aqueous medium but also examine the Cu²⁺ ions of the actual water samples. Nevertheless, L could be visual in Hela cells with excellent cell permeability, viz, monitoring exogenous Cu²⁺ ions as well as realizing an "on-off-on" process.

Varied Length Stokes Shift BODIPY-Based Fluorophores for Multicolor Microscopy

Multicolor microscopy tools necessary to localize and visualize the complexity of subcellular systems are limited by current fluorophore technology. While commercial fluorophores cover spectral space from the ultraviolet to the near infrared region and are optimized for conventional bandpass based fluorescence microscopy, they are not ideal for highly multiplexed fluorescence microscopy as they tend to have short Stokes shifts, restricting the number of fluorophores that can be detected in a single sample to four to five. Herein, we synthesized a library of 95 novel boron-dipyrromethene (BODIPY)-based fluorophores and screened their photophysical, optical and spectral properties for their utility in multicolor microscopy. A subset of our BODIPY-based fluorophores yielded varied length Stokes shifts probes, which were used to create a five-color image using a single excitation with confocal laser scanning microscopy for the first time. Combining these novel fluorophores with conventional fluorophores could facilitate imaging in up to nine to ten colors using linear unmixing based microscopy approaches.

Selective and Sensitive Fluorescein-Benzothiazole Based Fluorescent Sensor for Zn2+ Ion in Aqueous Media

An efficient fluorescent sensor based on fluorescein-benzothiazole (FB) for Zn²⁺ ion was synthesized and characterized systematically. FB exhibited selective and sensitive recognition toward Zn²⁺ in MeCN-H₂O (v/v = 2/1) over other cations due to the spirolactam ring-opening power of Zn²⁺. The complexation property of FB with Zn²⁺ ion was examined by ¹H NMR, ¹³C NMR and FTIR experiments. The stoichiometric ratio of the FB-Zn²⁺ complex was determined from a Job plot to be 1:1. The binding constant (K _a) of Zn²⁺ binding to FB was found to be 4.22 × 10⁴ M^- 1, with a detection limit of 5.64 μM. In addition, the practical utility of FB was explored in the form of test strips. Graphical Abstract.

PyrrolylBODIPYs: Syntheses, Properties, and Application as Environment-Sensitive Fluorescence Probes

Four pyrrole B-ring-functionalized pyrrolylBODIPYs and their B-ring unsubstituted analogues were synthesized from easily accessible starting 5-halo-2-formylpyrroles and were characterized by nuclear magnetic resonance, high-resolution mass spectrometry, X-ray analysis, and optical/electronic properties. In great contrast to the substitution(s) at the other two pyrrolic units, electron-donating substituent(s) at pyrrole B-ring bring significant blue shift of the absorption and emission bands. Cyclic voltammetry and density functional theory calculations indicate that this blue shift may be attributed to the increased highest occupied molecular orbital and the lowest unoccupied molecular orbital energy levels and the overall increase in the energy band gaps. These pyrrolylBODIPYs generally show intense absorption (centered at 570-624 nm) and fluorescence emission (582-654 nm) in nonpolar solvents. A gradual decrease in the fluorescence intensity was observed for these dyes with the increase in solvent dipolar moment, which combines with the red to far-red absorption/emission, rendering these pyrrolylBODIPYs potential applications as environment-sensitive fluorescence probes as demonstrated in this work for bovine serum albumin.

Amphiphilic BODIPY-Hydroporphyrin Energy Transfer Arrays with Broadly Tunable Absorption and Deep Red/Near-Infrared Emission in Aqueous Micelles

BODIPY-hydroporphyrin energy transfer arrays allow for development of a family of fluorophores featuring a common excitation band at 500 nm, tunable excitation band in the deep red/near-infrared window, and tunable emission. Their biomedical applications are contingent upon retaining their optical properties in an aqueous environment. Amphiphilic arrays containing PEG-substituted BODIPY and chlorins or bacteriochlorins were prepared and their optical and fluorescence properties were determined in organic solvents and aqueous surfactants. The first series of arrays contains BODIPYs with PEG substituents attached to the boron, whereas in the second series, PEG substituents are attached to the aryl at the meso positions of BODIPY. For both series of arrays, excitation of BODIPY at 500 nm results in efficient energy transfer to and bright emission of hydroporphyrin in the deep-red (640-660 nm) or near-infrared (740-760 nm) spectral windows. In aqueous solution of nonionic surfactants (Triton X-100 and Tween 20) arrays from the second series exhibit significant quenching of fluorescence, whereas properties of arrays from the first series are comparable to those observed in polar organic solvents. Reported arrays possess large effective Stokes shift (115-260 nm), multiple excitation wavelengths, and narrow, tunable deep-red/near-IR fluorescence in aqueous surfactants, and are promising candidates for a variety of biomedical-related applications.

Zinc(II)-Tetradentate-Coordinated Probe with Aggregation-Induced Emission Characteristics for Selective Imaging and Photoinactivation of Bacteria

The emergence of drug-resistant bacterial pathogens highlights an urgent need for new therapeutic options. Photodynamic therapy (PDT) has emerged as a potential alternative to antibiotics to kill bacteria, which has been used in clinical settings. PDT employs photosensitizers (PSs), light, and oxygen to kill bacteria by generating highly reactive oxygen species (ROS). PDT can target both external and internal structures of bacteria, which does not really require the PSs to enter bacteria. Therefore, bacteria can hardly develop resistance to PDT. However, most of the PSs reported so far are hydrophobic and tend to form aggregates when they interact with bacteria. The aggregation could cause fluorescence quenching and reduce ROS generation, which generally compromises the effects of both imaging and therapy. In this contribution, we report on a Zn(II)-tetradentate-coordinated red-emissive probe with aggregation-induced emission characterization. The probe could selectively image bacteria over mammalian cells. Moreover, the probe shows potent phototoxicity to both Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Bacillus subtilis).

Water-soluble, neutral 3,5-diformyl-BODIPY with extended fluorescence lifetime in a self-healable chitosan hydrogel

3,5-Diformyl-BODIPY cross-linked chitosan-based hydrogels exhibit fluorescence resonance energy transfer (FRET) dynamics, water solubility, self-healing ability and good values of BODIPY fluorescence lifetimes.

A Simple and Selective Fluorescent Sensor for Zn(2+) and H(+) Ions in Aqueous Solution with OR Logic Gate Function

The synthesis and properties of a new compound, viz., (N,N'-[1,10-phenanthroline-4,7-diyldi((E)methylylidene)]bis(1,10-phenanthrolin-5-amine) (1), is described. Compound 1 can be used as a selective fluorescent Zn(2+) sensor in buffered solution. Furthermore, 1 induces turn on fluorogenic response to H(+) ions. Finally, it is shown that an OR logic gate can be constructed with 1 by using Zn(2+) and H(+) as two-inputs. Graphical Abstract In this paper, the design, synthesis and physicochemical properties of a new compound 1 based on 1,10-phenanthroline scaffold, is reported. It is noted that 1 can be used as a selective fluorescent Zn(2+) sensor in 0.01 M HEPES buffer containing DMF (2 % v/v, pH = 7.4) at room temperature. Furthermore, the spectrophotometric results suggest that compound 1 can be used as a pH reporter in highly acidic conditions (pH < 5). Finally, it was also shown that an OR logic gate can be constructed with 1 by using Zn(2+) and H(+) as two-inputs.