Investigation of Photoinduced Sensitized Chemiluminescence by Sulfonated Phthalocyanines Using Flow Injection Technology

High-throughput photo-chemiluminescence imaging for HIV DNA determination based on a sulfur-doped graphitic carbonitride photocatalyst

In this work, a novel photo-chemiluminescence (PCL) array imaging technique was developed to detect HIV DNA sequences using water-dispersed ultrathin sulfur-doped g-C₃N₄ porous nanosheets (SCNNSs) as photocatalysts, with complementary chains of HIV DNA as the biorecognition elements. The PCL response was enhanced when a suitable amount of SCNNSs was used. The large specific surface area and π-conjugated structure of the SCNNSs provided a good platform for immobilizing the complementary chains of HIV DNA. When DNA complementary chains were present, some of the catalytically active sites of SCNNSs were blocked, and the PCL of the platform was weakened. When the HIV DNA was added, the DNA double chain was far away from the surfaces of the SCNNSs because the stacking interactions between the formed dsDNA and SCNNSs were weak. Therefore, the addition of the target HIV DNA sequence noticeably restored the signal. In the range of 5.00 × 10^-8 M to 200 × 10^-8 M, the enhanced PCL response was linearly related to the concentration of the HIV DNA sequence, and the detection limit (3S/N) was 1.50 × 10^-8 mol L^-1. In addition, the combination of SCNNSs with complementary chains of HIV DNA successfully produced a high-performance PCL imaging sensor. In these proof-of-concept experiments, we demonstrated that our method was fast, portable, and ultra-sensitive, with high throughput.

Conjugation of Phthalocyanine Photosensitizer with Poly(amidoamine) Dendrimer: Improved Solubility, Disaggregation and Photoactivity Against HepG2 Cells

OBJECTIVE

To improve solubility and to reduce aggregation, ZnPcC4 was conjugated to a third-generation poly-amidoamine dendrimer with amino end group (G3-PAMAM-NH2), which acts as a novel photodynamic therapy (PDT) drug carrier system.

METHODS

The phthalocyanines were synthesized by construction reaction. The nano drug was obtained from the conjugation of ZnPcC4 to G3-PAMAM-NH2, using EDC and NHS as coupling agents. The ZnPcC4@G3-PAMAM-NH2 conjugation was characterized by UV-Vis and MS. The 1O2 quantum yield of ZnPcC4@G3-PAMAM-NH2 in water was measured by the chemiluminescence method. The in vitro PDT responses of the studied photosensitizers were studied in hepatocellular carcinoma cell line HepG2 by MTT assay.

RESULTS

At ZnPcC4/G3-PAMAM-NH2 raw ratio of 100/1, the ZnPcC4 conjugate had improved solubility and reduced aggregation tendency in aqueous solution. At this optimum molar ratio, ZnPcC4- G3-PAMAM-NH2 inhibited HepG2 cells, with a half-maximal inhibitory concentration of 1.67 µg/mL upon infrared light exposure. The controls, including dark conditions, or media as well as G3-PAMAM-NH2 exposure, exhibited no inhibitory response.

CONCLUSION

The conjugation of phthalocyanine photosensitizer ZnPcC4 to poly-amidoamine dendrimer G3-PAMAM-NH2 improved the PDT outcomes, in which the optimized binding ratio of ZnPcC4 to G3-PAMAM-NH2 was 6:1.

An aptamer-based biosensor for sensitive thrombin detection with phthalocyanine@SiO2 mesoporous nanoparticles

Silica nanoparticles, with entrapped hydrophobic photosensitizer tetra-α-(2, 4-di-tert-butylphenoxy)-phthalocyaninato zinc (ZnPc(OAr)4), were synthesized by hydrolyzing triethoxyvinylsilane (TEVS) and 3-amino propyl triethoxysilane (APTES). The as-prepared nanoparticles, which were highly monodispersed spheres (about 100 nm), exhibited strong Q-band absorption of ZnPc(OAr)4 centered at 701 nm. The aqueous solubility of ZnPc(OAr)4 encapsulated in silica nanoparticles was obviously improved. The nanoparticles efficiently generated singlet oxygen ((1)O2) both in organic and aqueous solutions after being irradiated at suitable wavelength. The resulting (1)O2 then initiated chemiluminescence (CL) by reacting with a methyl cypridina luciferin analog (MCLA). Based on the photoinduced CL, a sensitive aptamer-based sandwich-type sensor was presented to detect human thrombin. Thrombin was first attached to Pc@SiO2 via secondary aptamer, and then they were collected, for CL determination, by beads with primary aptamer. The proposed approach, which was highly selective with a low detection limit of 80 pmol/L, minimized the nonspecific adsorption. Such an aptamer-based biosensor is feasible in screening biomarkers in complex matrices at ultratrace levels.

Isomeric separation and identification of tetra-, tri-, and di-β-sulphonic phthalocyanine zinc complexes

The synthesis, isomeric separation, and identification of β-sulphonic phthalocyanine zinc complexes were reported. While the sulphonic phthalocyanines have been studied extensively, the development of separation technology may enable deeper insights into their isomeric constitution. An ion-pair reversed-phase high performance liquid chromatography (IP-RP-HPLC) method was developed to separate the sulphonic phthalocyanine isomers. The results showed that the product of the condensation reaction is a mixture of all possible isomers with statistical distribution. Several isomers were obtained and structural determination was undertaken by NMR. Based on the IP-RP-HPLC elution sequence of these well-identified isomers, a relationship between the structure and efficiency was deduced: closely spaced intervals of sulphonic groups lead to higher hydrophobicity and shorter retention times on HPLC. Based on this relationship, each HPLC peak was assigned to the corresponding isomeric structure.