The improvement of biocompatibility by incorporating porphyrins into carbon dots with photodynamic effects and pH sensitivities

Photodynamic therapy (PDT) is a promising new treatment for cancer; however, the hydrophobic interactions and poor solubility in water of photosensitizers limit the use in clinic. Nanoparticles especially carbon dots have attracted the attention of the world^'s scientists because of their unique properties such as good solubility and biocompatibility. In this paper, we integrated carbon dots with different porphyrins to improve the properties of porphyrins and evaluated their efficacy as PDT drugs. The spectroscopic characteristics of porphyrins nano-conjugates were studied. Singlet oxygen generation rate and the light- and dark-induced toxicity of the conjugates were studied. Our results showed that the covalent interaction between CDs and porphyrins has improved the biocompatibility. The synthesized conjugates also inherit the pH sensitivity of the carbon dots, while the conjugation also decreases the hemolysis ratio making them a promising candidate for PDT. The incorporation of carbon dots into porphyrins improved their biocompatibility by reducing toxicity.

Kinetics and mechanism of formation of nickel(II)porphyrin and its interaction with DNA in aqueous medium

Kinetics between 5,10,15,20-tetrakis(N-methylpyridium-4-yl)porphyrin and Ni²⁺ species were investigated in aqueous solution at 25 ±1 °C in I = 0.10 M (NaNO₃). Speciation of Ni²⁺ was done in I = 0.10 M (NaNO₃) for knowing distribution of Ni²⁺ species with solution pH. Experimental data were compared with speciation diagram constructed from the values of hydrolysis constants of Ni²⁺ ion. Speciation data showed that hexaaquanickel(II) ions took place in hydrolysis reactions through formation of [Ni(OH₂)_6-n(OH)_n]^2-n species with solution pH. According to speciation of Ni²⁺ and pH dependent rate constants, rate expression can be written as: d[Ni(TMPyP)⁴⁺]/dt = (k₁[Ni²⁺_(aq)] + k₂[Ni(OH)⁺_(aq)] + k₃[Ni(OH)₂^o_(aq)] + k₄[Ni(OH)₃^-_(aq)])[H₂TMPyP⁴⁺], where k₁, k₂, k₃ and k₄ were found to be k₁ = (0.62 ± 0.22) × 10^-2; k₂ = (3.60 ± 0.40) × 10^-2; k₃ = (2.09 ± 0.52) × 10^-2, k₄ = (0.53 ± 0.04) × 10^-2 M^-1s^-1 at 25 ±1 °C, respectively. Formation of hydrogen bonding between [Ni(H₂O)₅(OH)]⁺ and [H₂TMPyP]⁴⁺ causes enhanced reactivity. Rate of formation of [Ni(II)TMPyP]⁴⁺ complex was to be 3.99 × 10^-2 M^-1s^-1 in I = 0.10 M, NaNO₃ (25 ± 1 °C). UV-Vis and fluorescence data suggested that [Ni(II)TMPyP]⁴⁺ and [H₂(TMPyP)]⁴⁺ interact with DNA via outside binding with self-stacking and intercalation, respectively.

SYNOPSIS

A folate-conjugated platinum porphyrin complex as a new cancer-targeting photosensitizer for photodynamic therapy

A new folate-conjugated platinum porphyrin complex (Por 4) was synthesized and characterized. The singlet oxygen production of the conjugates was evaluated through a 1,3-diphenylisobenzofuran method. The targeting ability and subcellular localization of Por 4 were confirmed by confocal laser scanning microscopy in HeLa cells (overexpression of FR) as well as in A549 cells (low expression of FR). The results suggested that the modification of the carboxyl group with a porphyrin compound did not decrease the binding affinity of folic acid to FR positive cancer cells. Moreover, the MTT assay using HeLa cells and A549 cells verified the low cytotoxicity of Por 4 in the dark. Upon irradiation, Por 4 showed noticeable improvement in toxicity against cancer cells with the overexpression of FR. Upon the treatment of Por 4 at the concentration of 20 μM, the cell viability was determined as 22% and 75% for HeLa and A549 cells, respectively, indicating that the folate-conjugated platinum porphyrin complex could be a promising PDT agent for cancer with overexpression of the folate receptor.

Synthesis, singlet oxygen generation and DNA photocleavage of β,β′-conjugated polycationic porphyrins

In this paper, three [Formula: see text],[Formula: see text]-conjugated cationic porphyrin compounds were designed and synthesized. The structure of the intermediates and desired porphyrins were confirmed by UV, IR, 1H NMR, MS and elemental analysis. The interaction modes between these porphyrins and ct-DNA were studied by UV-vis spectroscopy and fluorescence emission spectroscopy. The results showed that PCP 1 had an external binding mode with DNA at low DNA concentration and could intercalate DNA with the increase of concentration. PCP 2 interacted with DNA through an external binding mode, and PCP 3 could insert into DNA. The binding constants ([Formula: see text] between PCP1[Formula: see text]PCP3 and ct-DNA were calculated to be 8.41 × 104, 7.33 × 104 and 4.14 × 104 M[Formula: see text], respectively. The singlet oxygen (1O[Formula: see text] generation of PCP1[Formula: see text]PCP3 was determined by the 1,3-diphenylisobenzofuran (DPBF) method using tetrapyridylporphyrin (H2TMPyP) as a reference. The 1O2 generation rate of PCP1[Formula: see text]PCP3 followed the order of PCP2 >PCP1>H2TMPyP >PCP3. Subsequently, the photocleavage effect of porphyrins on pBR322 plasmid DNA was studied by gel electrophoresis. At 10.0 [Formula: see text]M, PCP1 and PCP2 could cleave DNA completely. At 2.0 [Formula: see text]M, the cleavage rate of DNA by PCP3 was 57.5%, which was significantly higher than that of H2TMPyP (38.8%). These results verified that the amount of cationic ions in the porphyrin structure could affect the binding modes of porphyrins with DNA and their cleavage ability of DNA.

Carbon Dots @ Platinum Porphyrin Composite as Theranostic Nanoagent for Efficient Photodynamic Cancer Therapy

Photosensitizers are light-sensitive molecules that are highly hydrophobic, which poses a challenge to their use for photodynamic therapy. Hence, considerable efforts have been made to develop carriers for the delivery of PSs. Herein, we synthesized a new theranostic nanoagent (CQDs@PtPor) through the electrostatic interaction between the tetraplatinated porphyrin complex (PtPor) and the negatively charged CQDs. The size and morphology of as-prepared CQDs and CQDs@PtPor were characterized by a series of methods, such as XRD, TEM, XPS, and FTIR spectroscopy. The CQDs@PtPor composite integrates the optical properties of CQDs and the anticancer function of porphyrin into a single unit. The spectral results suggested the effective resonance energy transfer from CQDs to PtPor in the CQDs@PtPor composite. Impressively, the CQDs@PtPor composite showed the stronger PDT effect than that of organic molecular PtPor, suggesting that CQDs@PtPor is advantageous over the conventional formulation, attributable to the enhanced efficiency of 1O2 production of PtPor by CQDs. Thus, this CQDs-based drug nanocarrier exhibited enhanced tumor-inhibition efficacy as well as low side effects in vitro, showing significant application potential in the cancer therapy.

Methylene violet 3RAX-conjugated porphyrin for photodynamic therapy: synthesis, DNA photocleavage, and cell study

A novel PDT photosensitizer which features great biomedical properties can be simply prepared.

Platinated porphyrin as a new organelle and nucleus dual-targeted photosensitizer for photodynamic therapy

Organelle and nucleus dual-targeted anticancer drugs are being increasingly used for efficient cancer therapy as they can attack the double vital sites of tumor cells. In this work, we synthesized and characterized two new porphyrin compounds Pt-Por-RB and Me-Por-RB. The spectral titration results suggest that both Pt-Por-RB and Me-Por-RB bind to DNA efficiently in an intercalation binding mode. Upon irradiation, Pt-Por-RB with low dark-cytotoxicity can rapidly generate singlet oxygen to damage the tumor cells through the process of photodynamic therapy. Compared with Me-Por-RB, Pt-Por-RB was not only internalized in the organelles, but also in the nuclei of HeLa cells, probably due to the presence of platinum complexes, as analyzed using the confocal laser scanning microscope. Thus, with the combination of organelle and nucleus dual-targeting property and high efficiency of singlet oxygen generation, Pt-Por-RB showed a significant therapeutic activity against tumor cells.

DNA Photocleavage and Binding Modes of Methylene Violet 3RAX and its Derivatives: Effect of Functional Groups

With 4′-amino-N,N-diethylaniline and aniline as starting materials, methylene violet 3RAX 1 and its derivatives 2–5 were synthesised. The five compounds were characterised by IR, UV-vis, and 1H NMR spectroscopy and mass spectrometry. The binding mode between the synthesised compounds and DNA were investigated. The results show that both compounds 1 and 5 bind to DNA by an intercalative mode, while compounds 2–4 interact with DNA through a mixed binding mode involving groove binding and electrostatic interactions. The photocleavage ability of the five compounds to DNA were calculated to be 38, 40, 30, 20, and 13 %, respectively, when their concentration was adjusted to 400 μM. The singlet oxygen production of compounds measured by the 1,3-diphenylisobenzofuran method was consistent with the trend of DNA photocleavage ability. The DNA studies suggest that the binding mode between methylene violet 3RAX and DNA, the ability of methylene violet 3RAX to generate singlet oxygen, and the DNA photocleavage activity could be adjusted through modification of the amino group on methylene violet 3RAX.