Small-molecule Organic Dyes Research Articles

Fluorogenic and Cell-Permeable Rhodamine Dyes for High-Contrast Live-Cell Protein Labeling in Bioimaging and Biosensing.

The advancement of fluorescence microscopy techniques has opened up new opportunities for visualizing proteins and unraveling their functions in living biological systems. Small-molecule organic dyes, which possess exceptional photophysical properties, small size, and high photostability, serve as powerful fluorescent reporters in protein imaging. However, achieving high-contrast live-cell labeling of target proteins with conventional organic dyes remains a considerable challenge in bioimaging and biosensing due to their inadequate cell permeability and high background signal. Over the past decade, a novel generation of fluorogenic and cell-permeable dyes has been developed, which have substantially improved live-cell protein labeling by fine-tuning the reversible equilibrium between a cell-permeable, nonfluorescent spirocyclic state (unbound) and a fluorescent zwitterion (protein-bound) of rhodamines. In this review, we present the mechanism and design strategies of these fluorogenic and cell-permeable rhodamines, as well as their applications in bioimaging and biosensing.

High permeability sub-nanometre sieve composite MoS2 membranes

Two-dimensional membranes have gained enormous interest due to their potential to deliver precision filtration of species with performance that can challenge current desalination membrane platforms. Molybdenum disulfide (MoS2) laminar membranes have recently demonstrated superior stability in aqueous environment to their extensively-studied analogs graphene-based membranes; however, challenges such as low ion rejection for high salinity water, low water flux, and low stability over time delay their potential adoption as a viable technology. Here, we report composite laminate multilayer MoS2 membranes with stacked heterodimensional one- to two-layer-thick porous nanosheets and nanodisks. These membranes have a multimodal porous network structure with tunable surface charge, pore size, and interlayer spacing. In forward osmosis, our membranes reject more than 99% of salts at high salinities and, in reverse osmosis, small-molecule organic dyes and salts are efficiently filtered. Finally, our membranes stably operate for over a month, implying their potential for use in commercial water purification applications.

Organic Fluorescent Dye-based Nanomaterials: Advances in the Rational Design for Imaging and Sensing Applications.

Self-assembled fluorescent nanomaterials based on small-molecule organic dyes are gaining increasing popularity in imaging and sensing applications over the past decade. This is primarily due to their ability to combine spectral properties tunability and biocompatibility of small molecule organic fluorophores with brightness, chemical and colloidal stability of inorganic materials. Such a unique combination of features comes with rich versatility of dye-based nanomaterials: from aggregates of small molecules to sophisticated core-shell nanoarchitectures involving hyperbranched polymers. Along with the ongoing discovery of new materials and better ways of their synthesis, it is very important to continue systematic studies of fundamental factors that regulate the key properties of fluorescent nanomaterials: their size, polydispersity, colloidal stability, chemical stability, absorption and emission maxima, biocompatibility, and interactions with biological interfaces. In this review, we focus on the systematic description of various types of organic fluorescent nanomaterials, approaches to their synthesis, and ways to optimize and control their characteristics. The discussion is built on examples from reports on recent advances in the design and applications of such materials. Conclusions made from this analysis allow a perspective on future development of fluorescent nanomaterials design for biomedical and related applications.

Two-dimensional MXene incorporated graphene oxide composite membrane with enhanced water purification performance

The limitations of instability and low permeability of graphene oxide (GO) membranes in aqueous applications, such as water treatment, represent significant obstacles to their wider application. In this paper, we describe the development and testing of a novel composite membrane based on GO and MXene. The unique heterogeneous structure of the GO/MXene membrane demonstrated a synergistic effect, in terms of substrate rejection and permeability, which varied according to the relative proportions of GO and MXene. Due to its advantageous two-dimensional (2D) interlayer channels and hydrophilicity, a composite membrane (~550 nm) with a GO/MXene mass ratio of 1/4 exhibited much greater water flux (71.9 L m−2 h−1.bar−1) compared to a reference GO membrane (6.5 L m−2 h−1.bar−1) under the same experimental conditions. Moreover, the composite membrane showed excellent stability in water over one month. The rejection of common small molecule organic dyes (NR, MB, CV, BB) was found to exceed 99.5%, and similar excellent removal efficiencies were found for two representative types of natural organic matter in raw waters (HA and BSA). The superior water flux of the GO/MXene composite membrane compared to the reference GO membrane was mainly attributed to the moderate increase of interlayer spacing of the membrane and the decrease of oxygen-containing functional groups.

Molecular design and application of novel small molecule organic dyes featuring bis(arylvinyl)phenyl amino group for dye-sensitized solar cells

Small molecule organic dyes (SMODs) FWD7 and FWD8 featuring novel donor bis(arylvinyl)phenyl amino (BAPA) were designed for dye-sensitized solar cells (DSSCs). Absorption spectra of FWD7 featuring furanyl groups and FWD8 featuring thiophenyl groups showed about 20 nm bathochromic shifts and obviously bigger molar extinction coefficients (ε) compared with FWD5 featuring phenyl groups. The DSSCs sensitized by FWD7 and FWD8 exhibited good photovoltaic parameters: short-circuit current density (Jsc) 9.88 and 11.59 mA cm−2, open-circuit voltage (Voc) 0.69 and 0.75 V, and power conversion efficiency (η) 4.89% and 6.01%, respectively. The bigger Rrec and τe values of FWD8 (Rrec = 88.53 Ω cm−2 and τe = 10.76 ms) compared with FWD7 (Rrec = 59.06 Ω cm−2 and τe = 6.80 ms) gave a good explanation of the former’s bigger Voc. The results showed that both bis(furanylvinyl)phenyl amino and bis(thiophenylvinyl)phenyl amino groups are good donor groups, while the latter is more efficient.

Low‐Cost, High‐Efficiency, and Efficiency Predictable Small Molecule Organic Dyes with Bis(4‐styryl)phenyl Amino Donor for Dye‐Sensitized Solar Cells (Solar RRL 6∕2019)

Low‐Cost, High‐Efficiency, and Efficiency Predictable Small Molecule Organic Dyes with Bis(4‐styryl)phenyl Amino Donor for Dye‐Sensitized Solar Cells (Solar RRL 6∕2019)

Low‐Cost, High‐Efficiency, and Efficiency Predictable Small Molecule Organic Dyes with Bis(4‐styryl)phenyl Amino Donor for Dye‐Sensitized Solar Cells

Three small molecule organic dyes (SMODs) with bis(4‐styryl)phenyl amino (BSPA) donor FWD4∼FWD6 are synthesized easily and applied as sensitizers for dye‐sensitized solar cells (DSSCs). The dipole moments (µ) of FWD4∼FWD6 are calculated by using density functional theory (DFT) to be 7.49, 9.64, and 9.22 D, respectively. The DSSCs based on FWD4∼FWD6 exhibit high power conversion efficiencies (η) of 5.83%, 7.62%, and 7.39%, respectively. The linear regression equation η = 0.817 µ–0.370 is created with R2 = 0.999 that reveals the equation owned high accuracy. Highly reliable linear equations are also obtained under different fabrication conditions, which indicates that the power conversion efficiency tendency is influenced only by these dyes’ intrinsic property, the dipole moment. The excellent linear correlation between the dipole moment and power conversion efficiency indicates that it is very likely to predict the power conversion efficiency precisely by calculating the dipole moment, which gives a convenient way to connect the experimental results with theoretical calculations for dyes with similar molecular structures.

Near-Infrared-II (NIR-II) Bioimaging via Off-Peak NIR-I Fluorescence Emission.

Significantly reduced photon scattering and minimal tissue autofluorescence levels in the second biological transparency window (NIR-II; 1000-1700 nm) facilitate higher resolution in vivo biological imaging compared to tradition NIR fluorophores (~700-900 nm). However, the existing palette of NIR-II fluorescent agents including semiconducting inorganic nanomaterials and recently introduced small-molecule organic dyes face significant technical and regulatory hurdles prior to clinical translation. Fortunately, recent spectroscopic characterization of NIR-I dyes (e.g., indocyanine green (ICG), IRDye800CW and IR-12N3) revealed long non-negligible emission tails reaching past 1500 nm. Repurposing the most widely used NIR dye in medicine, in addition to those in the midst of clinical trials creates an accelerated pathway for NIR-II clinical translation. This review focuses on the significant advantage of imaging past 1000 nm with NIR-I fluorophores from both a basic and clinical viewpoint. We further discuss optimizing NIR-I dyes around their NIR-II/shortwave infrared (SWIR) emission, NIR-II emission tail characteristics and prospects of NIR-II imaging with clinically available and commercially available dyes.

Chemical biology: Organic dyes for deep bioimaging.

Small-molecule organic dyes that fluoresce in the short-wave infrared region of the spectrum could improve the resolution of in vivo bioimaging methods. Such dyes have now been made by adapting those that fluoresce visible light.

Efficient Small Molecule Organic Dyes Containing Different Bridges in Donor Moieties for Dye-Sensitized Solar Cells

Small molecule (molecular weight is around 500Da) organic dyes were synthesized and used as sensitizers for the dye-sensitized solar cells (DSSCs). The optical and electrochemical properties, theoretical studies and photovoltaic parameters of DSSCs baseed on these dyes were systematically investigated. In order to extend the conjugation extent, two extra phenyl units were attached to triphenylamine (TPA) units bridged with single bonds, double bonds or triple bonds, respectively. The DSSCs based on FWDS exhibited well performances: the short-circuit current density (Jsc) of 10.04, 10.91 and 9.12mAcm−2, respectively; the open circuit voltage (Voc) of 0.77, 0.75 and 0.78V, respectively; the power conversion efficiency (η) of 5.65%, 6.04% and 5.19%, respectively. Two extra phenyl units attached via double or triple bonds increase the planar nature of these molecules, increasing the loading amount, which ultimately can correlate into the received efficiency. The results indicated that it is an effective way to get efficient dyes by introducing extra phenyl rings into donor moiety especially adopting double bonds as the bridge. Finally, efficient DSSCs were achieved by using small molecule TPA-type dyes FWD1, FWD2 and FWD3 as the sensitizers.

Impacts of Salt, Buffer, and Lipid Nature on Molecular Adsorption and Transport in Liposomes As Observed by Second Harmonic Generation

It is of great importance to interrogate the impact of local environment on the transport of small molecules across lipid bilayers, as they are key to the function and capabilities of eukaryotic cells and liposome-based delivery systems. Herein are described real-time studies of the molecular adsorption and transport kinetics of positively charged small-molecule organic dyes at the surface of liposomes under different buffer and salt conditions, made possible by application of second harmonic generation (SHG). The molecular transport of malachite green (MG) within the liposome bilayer is more rapid in 1,2-dioleoyl-sn-glycero-3-phospho-(1′-rac-glycerol) and 1,2-dioleoyl-sn-glycero-3-phospho-l-serine (DOPG and DOPS, respectively) liposomes in citrate buffer without added salts, whereas no adsorption or transport of MG is observed in trimethyl quinone-1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (QPADOPE) and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) liposomes. While the transport rate constant increa...

Small-molecule costimulatory blockade: organic dye inhibitors of the CD40–CD154 interaction

Costimulatory blockade is one of the most promising therapeutic targets in autoimmune diseases as well as in transplant recipients, and inhibition of the cluster of differentiation (CD)40-CD154 interaction, which is required for T cell activation and development of an effective immune response, is particularly promising in islet transplant recipients. Here, we report the ability of several small-molecule organic dyes to concentration dependently inhibit this interaction with IC(50) values in the low-micromolar range. They were found to be considerably more active in inhibiting this interaction than the tumor necrosis factor (TNF)-R1-TNF-alpha or B cell-activating factor (BAFF)-R-BAFF interaction, which are members of the same family. They specifically inhibited CD154-induced cell responses in human B cells as well as in THP-1 myeloid cells, which can serve as surrogate dendritic cells, at concentrations well below their cytotoxic concentrations determined in the same cells. Flow cytometry experiments confirmed their ability to inhibit the CD154-induced, but not the Staphylococcus aureus Cowan I- or phorbol 12-myristate 13-acetate-induced increase in the surface expression of CD54, CD40, and major histocompatibility complex class II. Accordingly, these compounds can be useful not only for experimental investigations involving the inhibition of the CD40-CD154 costimulatory interaction but can also provide important structure-activity relationship information and can serve as the starting point of a targeted drug discovery program.