Red fluorescent pyrazoline-BODIPY nanoparticles for ultrafast and long-term bioimaging

Novel near-infrared BODIPY-cyclodextrin complexes for photodynamic therapy

To meet the requirements of diagnosis and treatment, photodynamic therapy (PDT) is a promising cancer treatment with less side-effect. A series of novel BODIPY complexes (BODIPY-CDs) served as PDT agents were first reported to enhance the biocompatibility and water solubility of BODIPY matrix through the click reaction of alkynyl-containing BODIPY and azide-modified cyclodextrin (CD). BODIPY-CDs possessed superior water solubility due to the introduction of CD and their fluorescence emission apparently redshifted (>90 nm) on account of triazole units as the linkers compared to alkynyl-containing BODIPY. Moreover, all the BODIPY-CDs were no cytotoxicity toward NIH 3T3 in different drug concentrations from 12.5 to 200 μg/mL, and had a certain inhibitory effect on tumor HeLa cells. Particularly, BODIPY-β-CD exhibited high reactive oxygen species generation and excellent photodynamic therapy activity against HeLa cells compared to other complexes. The cell viability of BODIPY-β-CD was dramatically reduced up to 20% in the concentration of 100 μg/mL upon 808 nm laser irradiation. This architecture might provide a new opportunity to develop valuable photodynamic therapy agents for tumor cells.

Self-Assembled BODIPY Nanoparticles for Near-Infrared Fluorescence Bioimaging

In vivo optical imaging is an important application value in disease diagnosis. However, near-infrared nanoprobes with excellent luminescent properties are still scarce. Herein, two boron–dipyrromethene (BODIPY) molecules (BDP-A and BDP-B) were designed and synthesized. The BODIPY emission was tuned to the near-infrared (NIR) region by regulating the electron-donating ability of the substituents on its core structure. In addition, the introduction of polyethylene glycol (PEG) chains on BODIPY enabled the formation of self-assembled nanoparticles (NPs) to form optical nanoprobes. The self-assembled BODIPY NPs present several advantages, including NIR emission, large Stokes shifts, and high fluorescence quantum efficiency, which can increase water dispersibility and signal-to-noise ratio to decrease the interference by the biological background fluorescence. The in vitro studies revealed that these NPs can enter tumor cells and illuminate the cytoplasm through fluorescence imaging. Then, BDP-B NPs were selected for use in vivo imaging due to their unique NIR emission. BDP-B was enriched in the tumor and effectively illuminated it via an enhanced penetrability and retention effect (EPR) after being injected into the tail vein of mice. The organic nanoparticles were metabolized through the liver and kidney. Thus, the BODIPY-based nanomicelles with NIR fluorescence emission provide an effective research basis for the development of optical nanoprobes in vivo.

On the Use of Polymer-Based Composites for the Creation of Optical Sensors: A Review

Polymers are widely used in many areas, but often their individual properties are not sufficient for use in certain applications. One of the solutions is the creation of polymer-based composites and nanocomposites. In such materials, in order to improve their properties, nanoscale particles (at least in one dimension) are dispersed in the polymer matrix. These properties include increased mechanical strength and durability, the ability to create a developed inner surface, adjustable thermal and electrical conductivity, and many others. The materials created can have a wide range of applications, such as biomimetic materials and technologies, smart materials, renewable energy sources, packaging, etc. This article reviews the usage of composites as a matrix for the optical sensors and biosensors. It highlights several methods that have been used to enhance performance and properties by optimizing the filler. It shows the main methods of combining indicator dyes with the material of the sensor matrix. Furthermore, the role of co-fillers or a hybrid filler in a polymer composite system is discussed, revealing the great potential and prospect of such matrixes in the field of fine properties tuning for advanced applications.

3-(4-Formylphenyl)-triazole functionalized coumarins as violet-blue luminophores and n-type semiconductors: synthesis, photophysical, electrochemical and thermal properties

3-(4-Formylphenyl)-triazole-coumarin hybrid chromophores (FPhTCs) were synthesized in good yields, using a click chemistry protocol, and were also structurally characterized. Their photophysical, electrochemical and thermal properties were measured demonstrating that FPhTCs are luminescent in the blue-violet region of the electromagnetic spectrum, both in solution and the solid state. They showed an electrochemical band-gap values of 2.79 ± 0.08 eV, resistivity values between 10⁴ and 10⁵ Ω cm and are thermally stable up to 225 °C, properties that promise FPhTCs as good candidates for optoelectronic or imaging applications. Their solution and solid state photoluminescent properties are discussed and supported by theoretical calculations.

Engineering BODIPY-based near-infrared nanoparticles with large Stokes shifts and aggregation-induced emission characteristics for organelle specific bioimaging

Lipid droplets (LDs) and lysosomes, as two important subcellular organelles, play specific and indispensable roles in various cellular processes. The development of efficient LD- and lysosome-specific fluorescent bio-probes is of great importance. However, current commercial lipid droplet- (LD) and lysosome-specific fluorescent specific bio-probes often suffer from the aggregation-caused quenching (ACQ) effect, short absorption and emission wavelengths, poor photostability and low specificity. Herein, a typical ACQ luminogen BODIPY was directly conjugated to strong electron donating triarylamine units at its α-positions, giving near-infrared (NIR) fluorescent materials TPAB and 2TPAB with aggregation-induced emission (AIE). Both TPAB and 2TPAB nanoparticles were obtained by self-assembly, and showed NIR emissions, large Stokes shifts, good photostability and two-photon absorption. These nanoparticles presented remarkable bioimaging performances and were shown to specifically localize in LDs or lysosomes, respectively, depending on the number of triarylamine units attached. They have been successfully used to detect endogenous LD overproduction, and monitor abnormal activities of LDs/lysosomes, as well as real-time track the lipophagy process in cells. Their far NIR emission and two-photon excitation further supported their promising bioimaging application for lipid droplet tracking in liver tissue and live zebrafish larvae. Our work here enriches BODIPY based NIR AIE dyes and provides organelle specific bio-probes which are superior to currently used commercial ones.

Molecular engineering of fluorescent bichromophore 1,3,5-triaryl-Δ2-pyrazoline and 4-amino-1,8-naphthalimide molecular logic gates

Emissive bichromophoric solvatochromatic molecules are introduced as a new platform for the development of fluorescent molecular logic gates.

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.

Two-Photon Excitation-Based Imaging Postprocessing Algorithm Model for Background-Free Bioimaging

Bioimaging is a powerful strategy for studying biological activities, which is still limited by the difficulty of distinguishing obscured signals from high background. Despite the development of various new imaging materials and methods, target signals are still likely to be submerged in spontaneous fluorescence or scattering signals. Herein, a novel two-photon excitation-process-based imaging postprocessing algorithm model (2PIA) is introduced to minimize background noise, and triplet-triplet annihilation upconversion metal-organic frameworks (UCMOFs) are chosen as demonstration. Through the collection of several image stacks, the related polynomial of the luminescence intensity and excitation power was established, following splitting the desired signals from noise and obtaining the background-free images definitely. Both in vitro and in vivo experiments show that improved signal visibility is achieved through 2PIA and UCMOFs by removing the interference of scattering, bioluminescence, and other fluorescence materials. The imaging spatial resolution and tissue penetration depth were greatly enhanced. Benefiting from 2PIA, as low as 100 UCMOFs labeled cells can be identified from obscuring background easily after intravenous injection. This image postprocessing method combined with special two-photon excited luminescent materials can conduct biological imaging from complex background interference without using expensive instruments or delicate materials, which holds great promise for accurate biological imaging.

Highly efficient near-infrared BODIPY phototherapeutic nanoparticles for cancer treatment

A highly efficient NIR BODIPY nano-photosensitizer constructed by multi-intersection effects provides beneficial guidance for photodynamic and photothermal therapy.