Rational Design of Emissive NIR-Absorbing Chromophores: Rh(III) Porphyrin-Aza-BODIPY Conjugates with Orthogonal Metal-Carbon Bonds

Near-Infrared Absorbing Aza-BODIPY Dyes for Optoelectronic Applications

Organic dyes that absorb light in the visible to near-infrared region have garnered significant interest, owing to their extensive utility in organic photovoltaics and various biomedical applications. Aza-boron-dipyrromethene (Aza-BODIPY) dyes are a class of chromophores with impressive photophysical properties such as tunable absorption from the visible region towards near infrared (NIR) region, high molar absorptivity, and fluorescence quantum yield. In this review, we discuss the developments in the aza-BODIPYs, related to their synthetic routes, photophysical properties and their applications. Their design strategies, modifications in chemical structures, mode/position of attachment, and their impact on photo-physical properties are reviewed. The potential applications of aza-BODIPY derivatives such as organic solar cells, photodynamic therapy, boron-neutron capture therapy, fluorescence sensors, photo-redox catalysis, photoacoustic probes and optoelectronic devices are explained.

Smart and Multi-Functional Magnetic Nanoparticles for Cancer Treatment Applications: Clinical Challenges and Future Prospects

Iron oxide nanoparticle (IONPs) have become a subject of interest in various biomedical fields due to their magnetism and biocompatibility. They can be utilized as heat mediators in magnetic hyperthermia (MHT) or as contrast media in magnetic resonance imaging (MRI), and ultrasound (US). In addition, their high drug-loading capacity enabled them to be therapeutic agent transporters for malignancy treatment. Hence, smartening them allows for an intelligent controlled drug release (CDR) and targeted drug delivery (TDD). Smart magnetic nanoparticles (SMNPs) can overcome the impediments faced by classical chemo-treatment strategies, since they can be navigated and release drug via external or internal stimuli. Recently, they have been synchronized with other modalities, e.g., MRI, MHT, US, and for dual/multimodal theranostic applications in a single platform. Herein, we provide an overview of the attributes of MNPs for cancer theranostic application, fabrication procedures, surface coatings, targeting approaches, and recent advancement of SMNPs. Even though MNPs feature numerous privileges over chemotherapy agents, obstacles remain in clinical usage. This review in particular covers the clinical predicaments faced by SMNPs and future research scopes in the field of SMNPs for cancer theranostics.

BODIPY Conjugates as Functional Compounds for Medical Diagnostics and Treatment

Fluorescent dyes absorbing and emitting in the visible and near-IR regions are promising for the development of fluorescent probes for labeling and bio-visualization of body cells. The ability to absorb and emit in the long-wavelength region increases the efficiency of recording the spectral signals of the probes due to the higher permeability of the skin layers. Compared to other fluorescent dyes, BODIPYs are attractive due to their excellent photophysical properties-narrow absorption and emission, intense fluorescence, simple signal modulation for the practical applications. As part of conjugates with biomolecules, BODIPY could act as a biomarker, but as therapeutic agent, which allows solving several problems at once-labeling or bioimaging and treatment based on the suppression of pathogenic microflora and cancer cells, which provides a huge potential for practical application of BODIPY conjugates in medicine. The review is devoted to the discussion of the recent, promising directions of BODIPY application in the field of conjugation with biomolecules. The first direction is associated with the development of BODIPY conjugates with drugs, including compounds of platinum, paclitaxel, chlorambucil, isoxazole, capsaicin, etc. The second direction is devoted to the labeling of vitamins, hormones, lipids, and other biomolecules to control the processes of their transport, localization in target cells, and metabolism. Within the framework of the third direction, the problem of obtaining functional optically active materials by conjugating BODIPY with other colored and fluorescent particles, in particular, phthalocyanines, is being solved.

Penetration depth tunable BODIPY derivatives for pH triggered enhanced photothermal/photodynamic synergistic therapy

Improving the deep-tissue phototherapy (PDT) efficiency in the near-infrared (NIR) region has become one of the major challenges in clinics for cancer treatment. Developing intelligent photosensitizers (PSs) responding to tumor-specific signals sensitively to minimize side effects is another major challenge for tumor phototherapy. Herein, three phenyl-based boron dipyrromethene (BODIPY) compounds with different numbers of diethylaminophenyl groups introduced onto the BODIPY core have been designed and synthesized by the Knoevenagel condensation reaction. The absorbance of these compounds (BDPmPh, BDPbiPh, and BDPtriPh) can be controlled easily for realizing the tunable penetration depth. Moreover, the diethylamino groups in these designed PSs can serve as proton acceptors triggered by the low pH in lysosomes which can enhance the efficacy of photodynamic and photothermal therapy. The corresponding nanoparticles (NPs) of the compounds are prepared through a nanoprecipitation method and in vitro studies demonstrate that the ultra-low drug dosage of BDPtriPh NPs (half-maximal inhibitory concentration, IC50 = 4.16 μM) is much lower than that of BDPmPh NPs (50.09 μM) and BDPbiPh NPs (22.4 μM). In vivo fluorescence imaging shows that these NPs can be passively targeted to tumors by the enhanced permeability and retention (EPR) effect, and BDPtriPh NPs exhibit the fastest accumulation (about 4 hours). In vivo phototherapy indicates that BDPtriPh NPs with the longest NIR absorbance (813 nm) and highest photothermal conversion efficiency (60.5%) can effectively inhibit tumor growth and reduce side effects to normal tissues. This study provides a strategy to modulate the photoconversion characteristics of PSs for both penetration-depth-tunable and pH-dependent PDT/PTT synergistic cancer therapy in clinics.

A heavy atom-free copolymer for light triggered photodynamic and photothermal therapy of human prostate cancer cells

In this paper, a heavy-atom free co-polymer (NDTT) with high singlet oxygen quantum yield (48.2%) has been designed and prepared.

Photosensitizer synergistic effects: D-A-D structured organic molecule with enhanced fluorescence and singlet oxygen quantum yield for photodynamic therapy

Novel photosensitizers have been developed with high ¹O₂ quantum yields and strong fluorescence for cancer diagnosis and PDT.

The development of photosensitizers with high fluorescence intensity and singlet oxygen (¹O₂) quantum yields (QYs) is of great importance for cancer diagnosis and photodynamic therapy (PDT). Diketopyrrolopyrrole (DPP) and boron dipyrromethene (BODIPY) are two kinds of building block with great potential for PDT. Herein, a novel donor–acceptor–donor (D–A–D) structured organic photosensitizer DPPBDPI with a benzene ring as a π bridge linking DPP and BODIPY has been designed and synthesized. The results indicate that the combination of DPP with BODIPY can simultaneously increase the fluorescence QY (5.0%) and the ¹O₂ QY (up to 80%) significantly by the synergistic effect of the two photosensitizers. By nanoprecipitation, DPPBDPI can form uniform nanoparticles (NPs) with a diameter of less than 100 nm. The obtained NPs not only exhibit high photo-toxicity, but also present negligible dark toxicity towards HeLa cells, demonstrating their excellent photodynamic therapeutic efficacy. In vivo fluorescence imaging shows that DPPBDPI NPs can target the tumor site quickly with the enhanced permeability and retention (EPR) effect and can effectively inhibit tumor growth using photodynamic therapy even with low doses (0.5 mg kg^–1). The enhanced imaging and photodynamic performance of DPPBDPI suggest that the synergistic effect of DPP and BODIPY provides a novel theranostic platform for cancer diagnosis and photodynamic therapy.

Photochemical property of a Ru(ii) compound based on 3-(2-pyridyl)pyrazole and 2,2′-bipyridine for ablation of cancer cells

Ru(ii) compounds are potential candidates for photodynamic therapy (PDT).