High Molar Absorption Coefficient Research Articles

Enhanced Singlet Oxygen Generation in Aggregates of Naphthalene-Fused BODIPY and Its Application in Photodynamic Therapy.

Several reports are available on aggregation-induced emission and its applications in biomedical imaging and other material sciences. However, enhancement of singlet oxygen generation in nanoaggregates is rarely reported. Here, we report the synthesis of Naph-BODIPY Br2, which absorbs at 661 nm (monomer) with a high molar absorption coefficient. The presence of bromine promotes intersystem crossing, thereby enhancing the singlet oxygen quantum yield (ΦΔ ∼ 0.50 in methanol). In order to increase hydrophilicity, we developed Naph-BODIPY Br2 nanoaggregates (∼100 nm), which demonstrated aggregation-induced properties and exhibited a bathochromic shift with an absorption maximum at 757 nm. The bathochromic shift in the UV-vis spectra due to aggregation is corroborated by TD-DFT analysis. The computational data also confirm the presence of a low-lying triplet state, which enhances the generation of singlet oxygen, making it effective for photodynamic therapy. These aggregates showed excellent singlet oxygen generation in aqueous media, compared to their monomeric form and standard methylene blue. Their hydrophilic nature and high singlet oxygen generation enabled significant phototoxicity against human carcinoma cells with IC50 values of 4.06 ± 0.01 and 4.09 ± 0.1 μM, respectively, for MCF-7 and A549 cells upon 5 min exposure to light. Moreover, their phototoxicity further increases with an increasing exposure time of light for both cell lines. Notably, Naph-BODIPY Br2 nanoaggregates exhibited nearly zero dark cell toxicity and effectively induced apoptosis in cancer cells upon light activation, highlighting their potential as powerful photosensitizers for photodynamic cancer therapy.

RNA-Activatable Near-Infrared Photosensitizer for Cancer Therapy.

Photodynamic therapy (PDT) has recently come to the forefront as an exceptionally powerful and promising method for the treatment of cancer. Existing photosensitizers are predominantly engineered to target diverse biomolecules, including proteins, DNA, lipids, and carbohydrates, and have proven to greatly enhance the efficacy or specificity of PDT. However, it is noteworthy that there exists a conspicuous scarcity of photosensitizers specifically designed to target RNAs. Recognizing the crucial and multifaceted roles played by RNAs in various cellular processes and disease states, we have ventured into the development of a novel RNA-targeting photosensitizer, named Se-718, designed specifically for PDT-based cancer therapy. Se-718 has been engineered to exhibit a high molar absorption coefficient in the NIR region, which is crucial for effective PDT. More importantly, Se-718 has demonstrated a distinct RNA-targeting capability, as evidenced through rigorous testing in both circular dichroism and fluorescence experiments. Furthermore, Se-718 has been shown to display both type I and type II photodynamic properties. This unique characteristic enables the efficient killing of cancer cells under a wide range of oxygen conditions, both normoxic (21% O2) and hypoxic (2% O2). The IC50 of Se-718 can be as low as 100 nM, and its light-to-dark toxicity ratio is an impressive 215 times higher, outperforming most photosensitizers currently available. Moreover, in vivo studies conducted with tumor-bearing mice have demonstrated the excellent antitumor effects and high safety profile of Se-718. Considering the outstanding PDT efficacy of Se-718, we are optimistic that the development of RNA-targeting photosensitizers may provide an innovative and highly effective option for cancer therapeutics in the near future.

Photocytotoxic and cellular metabolism studies of curcuminoid-BF2 nanoaggregates in human carcinoma cells

Heavy atom-free photosensitizers represent a paradigm shift in the field of photodynamic therapy (PDT), offering a safer and more versatile alternative to traditional photosensitizers. As research progresses, the development of novel heavy-atom free compounds holds the potential to enhance the effectiveness and broaden the application of PDT, enabling the way for more targeted and less toxic cancer treatments. In this article, we report the application of heavy atom free curcuminoid BF2 (Diethylamine-CUR-BF2) containing acid sensitive amine group. Diethylamine-CUR-BF2 absorbs in deep red region at ∼618 nm and has high molar absorption coefficient. Nanoaggregates of Diethylamine-CUR-BF2 dispersed in aqueous medium showed high singlet oxygen production efficiency. The release kinetics of Diethylamine-CUR-BF2 showed efficient release of photosensitizer in slight acidic medium (at pH=5.0). Further, applications of Diethylamine-CUR-BF2 nanoaggregates in photocytotoxic studies using MCF-7 and A549 cells showed IC50 values 5.15 ± 1.4 μM and 8.05 ± 0.4 μM respectively. Cell death mechanism explored for photocytotoxicity studies utilizing Diethylamine-CUR-BF2 nanoaggregates is found to be apoptosis which is considered as normal programmed cell death pathway. Additionally, NADH FLIM studies revealed that the compound had an impact on cellular metabolism, prompting a shift from OXPHOS to glycolysis.

Efficacy of 222 nm radiation on degradation of organic micropollutants in water

In this work, a dielectric barrier discharge (DBD) based exciplex lamp emitting radiation at far UV-C wavelength 222 nm has been reported. The developed UV source has been used for the degradation of organic micropollutants (OMPs), i.e., brilliant red 5B (BR-5B) and sulfamethoxazole (SMX) in a batch-scale reactor. The degradation of OMPs has been performed using an advanced oxidation process by loading hydrogen peroxide (H2O2) as a radical promotor. The degradation efficiency and energy yield in the case of BR-5B have been found twofold as compared to SMX at similar experimental conditions, because of its high molar absorption coefficient at 222 nm radiation.

Triphenylamine based oxime ester photoinitiator for LED-induced free radical photopolymerization and 3D printing

With the development of light-emitting diode (LED), it is increasingly important to design and prepare photoinitiators that can be used for LED excitation. We designed and synthesized four new LED oxime ester photoinitiators (TOXEs) based on the triphenylamine group. Among them, the maximum absorption wavelengths of TOXE-3 and TOXE-4 are red-shifted to 402 nm and 397 nm, and have high molar absorption coefficients (ε) of 24315 M-1cm−1 and 29915 M-1cm−1, respectively, which are higher than that of ethenone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl] ethanone 1-(O-acetyloxime) (OXE02, 342 nm, 21836 M-1cm−1), indicating that it can be used in LED polymerization. Investigating the photopolymerization properties of the TOXEs/α, ω-diacryloyl poly(ethylene glycol) (PEGDA) system, under LED@365 nm irradiation, the double bond conversion rate (DC) of TOXE-1 and TOXE-2 were 83 % and 92 %, which were higher than OXE02 (80 %). Under LED@405 nm irradiation, the DC of TOXE-3 and TOXE-4 are 80 % and 78 % respectively, which is higher than that of OXE02 (52 %). To improve the photoinitiation ability of TOXEs, a two-component photoinitiation system using bis(4-tert-butylphenyl) iodonium (Iod) as an additive was tested. The DC of TOXEs has been improved under different light sources. Under LED@480 nm irradiation, the final DC of TOXE-4/Iod/PEGDA is 83 %. In addition, TOXE-3 and TOXE-4 can be applied to the laser cladding deposition (LCD) 3D printers. At the same time, we conduct research and verification on the polymerization mechanism of TOXEs through steady-state photolysis and electron spin resonance spin trapping experiments (ESR-ST). In addition, cytotoxicity assay and thermal stability testing showed that TOXEs exhibited excellent biocompatibility and thermal stability.

Matching periodate peak absorbance by far UVC at 222 nm promotes the degradation of micropollutants and energy efficiency

Periodate (PI)-based advanced oxidation processes have gained increasing interest. This study for the first time elevates the light-activation capacity of PI by using far UVC at 222 nm (UV222/PI) without extra chemical inputs. The effectiveness and the underlying mechanisms of UV222/PI for the remediation of micropollutants were studied by selecting atenolol (ATL) as a representative. PI possessed a high molar absorption coefficient of 9480–6120 M−1 cm−1 at 222 nm in the pH range of 5.0–9.0, and it was rapidly decomposed by UV222 with first-order rate constants of 0.0055 to 0.002 s−1. ATL and the six other organic compounds were effectively degraded by the UV222/PI process under different conditions with the fluence-based rate constants generally two to hundred times higher than by UVA photolysis. Hydroxyl radical and ozone were confirmed as the major contributors to ATL degradation, while direct photolysis also played a role at higher pH or lower PI dosages. Degradation pathways of ATL were proposed including hydroxylation, demethylation, and oxidation. The high energy efficiency of the UV222/PI process was also confirmed. This study provides a cost-effective and convenient approach to enhance PI light-response activity for the treatment of micropollutants.

Plasma membrane-anchored fluorescent tracker based on boron-dipyrromethene

The construction of a stable membrane tracker has significant implications for the visualization of the membrane in live cells. However, most current plasma trackers are not suitable for tracking plasma membranes for a long time due to their limited retention time. Herein, Mem580-F-Sulfo is designed to target and anchor cell membranes, and therefore track cell membranes for a longer time. This tracker is composed of a lipophilic BODIPY derivative and a hydrophilic zwitterion to form an amphiphilic structure, which enables its targeting ability toward cell membranes. Moreover, a reactive ester group is included to bind with proteins through covalent bonds in cell membranes non-specifically, which extends retention time in cell membranes. Mem580-F-Sulfo shows intense brightness (94600) with a high molar absorption coefficient of up to about 100000 L·mol-1·cm-1 and a fluorescence quantum yield of up to 0.97. It shows fast cell membrane targeting ability and long retention up to 90 min. In brief, this work has not only developed a tracker with good cell membrane targetability but also provided a new strategy for improving the targeting stability of cell membranes.

Towards sustainable solar cells: unveiling the latest developments in bio-nano materials for enhanced DSSC efficiency

Abstract Fossil fuels—instrumental in powering the nineteenth-century Industrial Revolution—are now under heightened scrutiny due to environmental concerns and carbon emissions. Consequently, there is a global impetus towards achieving carbon-neutral energy production, with solar energy emerging as a cornerstone in this transition. Over the past three decades, dye-sensitized solar cells (DSSCs) have gained increasing prominence due to their unique advantages. This review elucidates several crucial elements essential to DSSC construction, notably bio-nano materials, prized for their structural flexibility, cost-effectiveness and high molar absorption coefficient. It delves into the intricate relationship between molecular structure and DSSC performance, showcasing significant advancements with light-to-power conversion efficiencies reaching 11%. A comprehensive analysis of the photovoltaic performance of DSSCs utilizing bio-nano-based dyes offers invaluable insights into the state of this rapidly evolving industry. Key components under scrutiny include transparent conductive oxide (TCO) layers, physical techniques for metal oxide deposition onto TCO thin films, diverse dye variants and foundational knowledge of components ripe for growth and enhancement. Moreover, the review outlines the latest breakthroughs in the field, providing glimpses into the current status of prototype DSSCs.

Synthesis and characterization of α-(4-(2,3-hydroxylpropoxy)phenylimino)-o-cresol Schiff base as an effective UV-absorber for ink systems

Schiff base is a diverse group of organic compounds and has potential as a UV absorber for ink systems due to its high UV protection, simple synthesis, and high dispersion in organic matrices. In this work, a novel Schiff base α-(4-(2,3-dihydroxylpropoxy)phenylimino)-o-cresol (named GMA-I) was synthesized and investigated as a UV absorber for ink system. The UV-protection of GMA-I was evaluated on ink-coated duplex substrate samples via color measurement using an accelerated UV test chamber. The results showed that the GMA-I exhibited strong absorption in both UVA and UVB regions with an extra high molar absorption coefficient of 43,554 M−1 cm−1, and high thermal stability of 271.4 °C. Interestingly, the GMA-I showed high UV protection for ink platform at low content of 2 wt% thank to the intramolecular proton transfer mechanism and therefore potential as a UV absorber additive for ink systems.

Highly Efficient Photoanodic Material: Utilizing Dihydrolipoic Acid‐Functionalized CuInS2 Quantum Dots in Photoelectrochemical Cells

AbstractCopper indium sulfide quantum dots (CIS QDs) possess the desired optical properties to act as photoanodic material in photoelectrochemical cells, like a high molar absorption coefficient over the entire visible spectrum and long exciton lifetimes. The already reported procedures that utilize photoanodes based on such nanoparticles, however, exploit harsh conditions or utilize non‐scalable, expensive, and low‐yield syntheses. Here, the construction of CIS QDs adsorbed onto TiO2/FTO photoanodes (FTO = fluorine‐doped tin oxide) with a process aimed at avoiding these issues is proposed. In particular, the employment of dihydrolipoic acid as the ligand allows an easy and cost‐effective functionalization. CdS layers are deposited onto the nanoparticles to enhance the photoelectrochemical properties. Full characterization of the steady–state and transient photoelectrochemical properties of the electrodes is performed to gain information on the interfacial dynamics among the different components of the electrode. Maximum IPCEs of the order of 50% and a spectral sensitization extended up to 700 nm are obtained in the optimized conditions.

Synthesis, molecular dynamics, antimicrobial activity and wound healing application of new methylidene dyes based on pyrrolinone esters

A new methylidene dye based on the direct condensation of an aldehyde derivative with a pyrrolinone ester derivative was successfully prepared as well as its quaternary ammonium salt analogue. The structures of all synthesized dyes were confirmed using NMR, Mass and IR spectra. The absorption and emission spectra of the synthesized dyes were investigated. The synthesized methylidene dye and its cationic form showed high molar absorption coefficients and a significant emission of the cationic dye analogue solution was observed. The antibacterial affinity using the disk diffusion method was investigated for six potential skin infection causing microbial pathogens, including two Gram-negative species (Pseudomonas aeruginosa and Proteus mirabilis), two Gram-positive species (Staphylococcus aureus and Staphylococcus epidermidis), and two fungal species (Candida albicans and Rhizomucor miehei) by recording the inhibition zone as well as studying the killing time effect for the prepared dyes. The in vitro wound healing application and the effect of cationized Dye 2 on the healing progress showed very effective and faster healing at a concentration of 100 µg/mL (IC50). Molecular dynamics simulation studies of Dye 1 and Dye 2 were carried out to compute binding free energies using Generalized Born Surface Area (MM/GBSA) in molecular mechanics. Furthermore, computational studies revealed that Dye 2 showed high affinity toward the active site of DNA gyrase B, which provides a solid framework for new structure-based design initiatives.

Design and Synthesis of Difluoroboronite Curcuminoid derivatives for application in photodynamic therapy

This research paper describes the synthesis of two derivatives, 1 and 2, using aldehydes containing acid-sensitive groups. Both derivatives are of the donor-acceptor-donor type and exhibit absorption and emission in the red region. Derivative 1 has an absorption peak at 647 nm and an emission peak at approximately 713 nm. These molecules possess intramolecular charge transfer properties, allowing them to populate a triplet state that produces singlet oxygen, which plays a crucial role in cell death. Furthermore, the acid-sensitive groups on these derivatives enable selective accumulation in slightly acidic cancer cells. The cellular uptake of these derivatives can be enhanced through the formation of nanoaggregates, with average particle sizes of 112 nm and 81 nm for 1 and 2, respectively. While derivative 2 has a higher capacity for singlet oxygen production (φΔ∼0.40) and better fluorescence quantum yield than derivative 1, both molecules have high molar absorption coefficients and can serve as potential photosensitizers for cancer treatment.

Crucial Breakthrough of BODIPY‐Based NIR‐II Fluorescent Emitters for Advanced Biomedical Theranostics

AbstractFluorescence imaging in the second near‐infrared window (NIR‐II, 1000–1700 nm) has aroused immense attention for biomedical applications, offering exceptional advantages such as ultra‐low photon scattering and increased tissue penetration. Among the NIR‐II‐emitted organic dyes, Boron dipyrromethene (BODIPY), has emerged as a noteworthy candidate. BODIPY, distinguished by its controllable molecular structure and optical properties, outstanding fluorescence quantum yields, high molar absorption coefficients, and remarkable chemical stability, has undergone comprehensive investigation and extensive exploration within the realm of biological theranostics. This work aims to provide a comprehensive summary of the advancements in the development and design strategies of NIR‐II BODIPY fluorophores tailored for advanced biological phototheranostics. Initially, the work elucidates several representative and controllable strategies, concluding the electron‐programming strategy, extension of the conjugated backbone, J‐aggregation strategy, and strategic establishment of activatable fluorophores, which enhance the NIR‐II fluorescence of BODIPY skeletons. Subsequently, developments in NIR‐II fluorescent BODIPY‐based nanoplatforms for biological applications are intricately elaborated. In conclusion, this work outlines future efforts and directions for refining NIR‐II BODIPY to meet evolving clinical demands. It is anticipated that this contribution may provide a feasible reference for the strategic design of organic NIR‐II fluorophores, thereby advancing their potential in future clinical practices.

The Advent of Bodipy-based Chemosensors for Sensing Fluoride Ions: A Literature Review.

The detection of fluoride ions in water and other sources is crucial because they can harm human health if they exceed the safe limit of 1-1.5 ppm. BODIPY (boron dipyrromethene) dyes are promising fluorophores for chemosensors, and their design and modification have attracted a lot of attention. Their advantages include visible light excitation and emission, high molar absorption coefficients (ε) and fluorescence quantum yields [ϕ (λ)], and flexible scaffold manipulation for various applications. In this article, we review the progress of BODIPY-based sensors for fluoride ions from the early 2000s to the present. We focus on the different scaffold modifications of the sensors and their corresponding responses, as well as the underlying photophysical mechanisms and potential uses of each sensor.

Intercalating of AIEgens into MoS2 nanosheets to induce crystal phase transform for enhanced photothermal and photodynamic synergetic anti-tumor therapy

A MoS2-based nanotherapeutic platform was developed for synergetic photothermal and photodynamic anti-tumor therapy. AIEgens TFPy-SH molecules were intercalated into MoS2 nanosheets (MoS2 NSs) with S-deficiencies to give the nanocomposite MoS2-TFPy. The AIEgens intercalation expanded the interlayer spacing of MoS2 NSs and induced the transform of MoS2 crystal phase from 2H to 1T, offering MoS2-TFPy nanocomposite high molar absorption coefficient (5.65 L g−1 cm−1), excellent photothermal conversion efficiency under near-infrared (NIR) laser irradiation (38.3%), and favorable intracellular reactive oxygen species (ROS) generation capacity. The positively charged MoS2-TFPy were mainly distributed in mitochondria after cell up-taking, and achieved 1+1>2 anti-tumor effect attributed to its favorable photothermal and photodynamic properties. The high structure and physiological stability, favorable biocompatibility, excellent photothermal and photodynamic therapy effect make the MoS2-TFPy nanoplatform an promising candidate in biomedical clinical applications.

Design of donor-acceptor conjugated polymers based on diketopyrrolopyrrole for NIR-II multifunctional imaging.

Diketopyrrolopyrrole (DPP) is an excellent photosensitizer and photothermal agent with the advantages of good planarity, strong electron affinity, high electron mobility, easy purification, easy structural modification and high molar absorption coefficient. It is regarded as one of the ideal choices for the design and synthesis of efficient organic photovoltaic materials. Therefore, two kinds of donor-acceptor (D-A) conjugated polymers were designed and synthesized with DPP as the acceptor, and their optical properties and applications in the near-infrared region were studied. The quantum yield (QY) of PBDT-DPP is 0.46%, and the highest temperature reached within 10 minutes after irradiation with a 660 nm laser is 60 °C. Another polymer, EDOT-DPP, has a QY of 0.48%, and its semiconductor polymer nanoparticle aqueous solution can reach 60 °C within 12 minutes under laser irradiation, achieving photothermal treatment of nude mice tumors. Both polymer NPs have good biocompatibility and promising applications in bioimaging and photothermal therapy.

Potentiating light-harvesting tactics through an A-D-A structure: repolarization of tumor-associated macrophages through phototherapy.

Aiming to decrease the recurrence of tumors and achieve patient satisfaction, the elicitation of immunotherapy and its integrated synergistic employment is a bright new direction in oncotherapy, yet an emergently challenging task. In particular, tumor-associated macrophage (TAM) regulation though light-induced photodynamic and photothermal therapy (PDT and PTT) is regarded as a powerful approach, which focuses on the systemic immune system instead of the tumor itself. Herein, this study reports an acceptor-donor-acceptor (A-D-A) aggregation-induced emission luminogen (AIEgen), named TPA-2CN, which was applied as a photosensitizer (PS) and photothermal agent (PTA). Attributed to its A-D-A structure and AIE properties, TPA-2CN exhibits a high molar absorption coefficient and acts as a perfect template in regulating radiative and nonradiative transitions, which mainly utilize excited energy. The generation of type I reactive oxygen promoted its application in hypoxic tumor sites and the combination of hyperpyrexia forcefully induces macrophages to polarize towards the immune response M1 phenotype. In in vitro and in vivo, the successful reversion and reprogramming of the immune microenvironment was impressively proved. This method optimally concentrated immune therapy, PDT and PTT as one and exhibited excellent synergistic therapeutic effects with good biosafety.

BODIPY-based photocages: rational design and their biomedical application.

Photocages, also known as photoactivated protective groups (PPGs), have been utilized to achieve controlled release of target molecules in a non-invasive and spatiotemporal manner. In the past decade, BODIPY fluorophores, a well-established class of fluorescent dyes, have emerged as a novel type of photoactivated protective group capable of efficiently releasing cargo species upon irradiation. This is due to their exceptional properties, including high molar absorption coefficients, resistance to photochemical and thermal degradation, multiple modification sites, favorable uncaging quantum yields, and highly adjustable spectral properties. Compared to traditional photocages that mainly absorb UV light, BODIPY-based photocages that absorb visible/near-infrared (Vis/NIR) light offer advantages such as deeper tissue penetration and reduced bio-autofluorescence, making them highly suitable for various biomedical applications. Consequently, different types of photoactivated protective groups based on the BODIPY skeleton have been established. This highlight provides a comprehensive overview of the strategies employed to construct BODIPY photocages by substituting leaving groups at different positions within the BODIPY fluorophore, including the meso-methyl position, boron position, 2,6-position, and 3,5-position. Furthermore, the application of these BODIPY photocages in biomedical fields, such as fluorescence imaging and controlled release of active species, is discussed.

Luminescent Mono‐, Di‐ and Trisubstituted 2,4,6‐Triphenylpyridine‐Based Molecules: Synthesis and Properties

AbstractThe chromophores based on a pyridine central acceptor and one/two/three peripheral substituents of different electronic and spatial nature have been designed and synthesized. The structure‐property relationship was studied using differential scanning calorimetry, cyclic voltammetry, UV‐Vis and emission spectroscopy. A study of the thermal properties of the synthesized compounds showed that the presence of a 3,6‐bis(tert‐butyl)carbazole fragment leads to a significant increase in the glass transition temperature of the compounds. Photophysical studies have revealed that N,N‐diphenylamine‐containing pyridines are characterized by a high fluorescence quantum yield. In this regard, the expediency of the simultaneous presence in the structure of chromophores of electron‐donating groups of different natures has been proven, since this approach makes it possible to obtain compounds with high fluorescence quantum yield and molar absorption coefficient, as well as a narrow band gap and a deep level of the highest occupied molecular orbital.

Developing Bright Afterglow Materials via Manipulation of Higher Triplet Excited States and Relay Synthesis in Difluoroboron β‐Diketonate Systems

AbstractAfterglow brightness represents one of the most important characteristics in the application of afterglow materials. High molar absorption coefficient, high afterglow efficiency, and long afterglow lifetimes are required to achieve intense afterglow. However, current strategies cannot simultaneously fulfill these requirements due to specific intrinsic problems. Here, based on the understanding of difluoroboron β‐diketonate systems, the manipulation of higher triplet excited states is conceived to selectively enhance intersystem crossing with phosphorescence lifetimes remaining long. Aromatic substrates, which possess specific HOMO levels and T1 levels, are selected for relay synthesis to form difluoroboron β‐diketonate compounds with very close‐lying S1 and T2 levels; according to the energy gap law, such systems exhibit strong intersystem crossing. Upon doping into rigid matrices, the resultant difluoroboron β‐diketonate systems display the brightest ambient afterglow that has ever been observed.