Glycosyl-Modified Diporphyrins for in Vitro and in Vivo Fluorescence Imaging

Photoinduced charge transfer in Zn(II) and Au(III)-ligated symmetric and asymmetric bacteriochlorin dyads: A computational study

The excited-state properties and photoinduced charge-transfer (CT) kinetics in a series of symmetrical and asymmetrical Zn- and Au-ligated meso-meso-connected bacteriochlorin (BChl) complexes are studied computationally. BChl derivatives, which are excellent near-IR absorbing chromophores, are found to play a central role in bacterial photosynthetic reaction centers but are rarely used in artificial solar energy harvesting systems. The optical properties of chemically linked BChl complexes can be tuned by varying the linking group and involving different ligated metal ions. We investigate charge transfer in BChl dyads that are either directly linked or through a phenylene ring (1,4-phenylene) and which are ligating Zn or Au ions. The directly linked dyads with a nearly perpendicular arrangement of the BChl units bear markedly different properties than phenylene linked dyads. In addition, we find that the dielectric dependence of the intramolecular CT rate is very strong in neutral Zn-ligated dyads, whereas cationic Au-ligated dyads show negligible dielectric dependence of the CT rate. Rate constants of the photo induced CT process are calculated at the semiclassical Marcus level and are compared to fully quantum mechanical Fermi's golden rule based values. The rates are calculated using a screened range separated hybrid functional that offers a consistent framework for addressing environment polarization. We study solvated systems in two solvents of a low and a high scalar dielectric constant.

Novel hydrophilic galactose-conjugated chlorin e6 derivatives for photodynamic therapy and fluorescence imaging

We synthesized new hydrophilic chlorin e₆ derivatives with two and four galactose fragments conjugated to the macrocycle via carbon atom in position 6 of the galactose fragment. Galactose fragments were inserted by alkylation of the amino groups of chlorin e₆ amides with one and two ethylene diamine fragments on the macrocycle periphery with triflate of diacetone galactose, followed by removal of diisopropylidene protection by 70% aqueous trifluoroacetic acid. The synthesized compounds were shown to be capable of penetrating the membrane of HeLa cells; they have intense red fluorescence inside the cell and have phototoxic properties towards HeLa cells (upon LED irradiation at 660 nm and light exposure value of 12 J/cm²). These properties, along with water solubility, allow us to consider the synthesized compounds to be promising as potential antitumor PSs and diagnostic compounds for visualizing malignant tumors and creating on their basis preparations for simultaneous diagnostics and therapy of oncological diseases.

Symmetrical and Nonsymmetrical Meso-Meso Directly Linked Hydroporphyrin Dyads: Synthesis and Photochemical Properties

A series of a rigid meso-meso directly linked chlorin-chlorin, chlorin-bacteriochlorin, and bacteriochlorin-bacteriochlorin dyads, including free bases as well as Zn(II), Pd(II), and Cu(II) complexes, has been synthesized, and their absorption, emission, singlet oxygen (¹O₂) photosensitization, and electronic properties have been examined. Marked bathochromic shifts of the long-wavelength Q _y absorption band and increase in fluorescence quantum yields in dyads, in comparison to the corresponding monomers, are observed. Nonsymmetrical dyads (except bacteriochlorin-bacteriochlorin) show two distinctive Q _y bands, corresponding to the absorption of each dyad component. A nearly quantitative S₁-S₁ energy transfer between hydroporphyrins in dyads, leading to an almost exclusive emission of hydroporphyrin with a lower S₁ energy, has been determined. Several symmetrical and all nonsymmetrical dyads exhibit a significant reduction in fluorescence quantum yields in solvents of high dielectric constants; this is attributed to the photoinduced electron transfer. The complexation of one macrocycle by Cu(II) or Pd(II) enhances intersystem crossing in the adjacent, free base dyad component, which is manifested by a significant reduction in fluorescence and increase in quantum yield of ¹O₂ photosensitization.

Fluorescent Nanoparticles with Tissue-Dependent Affinity for Live Zebrafish Imaging

Carbon quantum dots (CDs) are widely investigated because of their low toxicity, outstanding water solubility, and high biocompatibility. Specifically, fluorescent CDs have attracted ever-increasing interest. However, so far, only a few studies have focused on assessing the fluorescence of nitrogen-doped CDs (N@CDs) during in vivo exposure. Here, we describe a strategy for low-cost, one-pot synthesis of N@CDs. The low toxicity and suitability of the N@CDs for fluorescence imaging are validated using zebrafish (ZF) as a model. Strong fluorescence emission from ZF embryos and larvae confirms the distribution of N@CDs in ZF. The retention of N@CDs is very stable, long lasting, and with no detectable toxicity. The presence of a strong fluorescence at the yolk sac, especially in the vicinity of the intestine, suggests that a high content of N@CDs entered the digestive system. This indicates that N@CDs may have potential imaging applications in elucidating different aspects of lipoprotein and nutritional biology, in a ZF yolk lipid transport and metabolism model. On the other hand, the presence of a strong selective fluorescence at the eyes and melanophore strips at the trunk and tail region of ZF larvae suggests that N@CDs has a high melanin-binding affinity. These observations support a novel and revolutionary use of N@CDs as highly specific bioagents for eye and skin imaging and diagnosis of defects in them. N@CDs are known for their multifunctional applications as highly specific bioagents for various biomedical applications because of their exceptional biocompatibility, photostability, and selective affinity. These characteristics were validated in the developmental ZF model.

Decoration of porphyrin with tetraphenylethene: converting a fluorophore with aggregation-caused quenching to aggregation-induced emission enhancement

A new porphyrin derivative with aggregation-induced emission enhancement was synthesized via tetraphenylethene decoration and it demonstrates bright imaging ability in vitro.

Carbon Quantum Dots for Zebrafish Fluorescence Imaging

Carbon quantum dots (C-QDs) are becoming a desirable alternative to metal-based QDs and dye probes owing to their high biocompatibility, low toxicity, ease of preparation, and unique photophysical properties. Herein, we describe fluorescence bioimaging of zebrafish using C-QDs as probe in terms of the preparation of C-QDs, zebrafish husbandry, embryo harvesting, and introduction of C-QDs into embryos and larvae by soaking and microinjection. The multicolor of C-QDs was validated with their imaging for zebrafish embryo. The distribution of C-QDs in zebrafish embryos and larvae were successfully observed from their fluorescence emission. the bio-toxicity of C-QDs was tested with zebrafish as model and C-QDs do not interfere to the development of zebrafish embryo. All of the results confirmed the high biocompatibility and low toxicity of C-QDs as imaging probe. The absorption, distribution, metabolism and excretion route (ADME) of C-QDs in zebrafish was revealed by their distribution. Our work provides the useful information for the researchers interested in studying with zebrafish as a model and the applications of C-QDs. The operations related zebrafish are suitable for the study of the toxicity, adverse effects, transport, and biocompatibility of nanomaterials as well as for drug screening with zebrafish as model.

Protoporphyrin incorporated alginate hydrogel: preparation, characterization and fluorescence imaging in vivo

A protoporphyrin incorporated alginate hydrogel exhibits the fluorescence ability to locate a drug and carrier with multispectral fluorescence imaging in vivo.

Ultrafast synthesis of nitrogen-doped carbon dots via neutralization heat for bioimaging and sensing applications

Ultrafast synthesis (within 2 min) of nitrogen-doped carbon dots was achieved using neutralization heat with glucose as a precursor. The hydroxyl groups on the dots' surface make them easy to conjugate with boronic acid. The dots were used for zebrafish embryo imaging and ovalbumin sensing.