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Nowadays, brain natriuretic peptide (BNP-32) is fundamental to early cardiovascular clinical diagnosis, whose accurate assay is of significance by photoelectrochemistry (PEC) for the low background and high precision. Herein, a novel enhanced PEC platform was built by successive deposition of N-doped ZnO nanopolyhedra (N-ZnO NP) and protoporphyrin IX (PPIX). Specifically, the N-ZnO NP with a narrow bandgap of 2.60 eV was synthesized by direct calcination of zeolitic imidazole framework-8 (ZIF-8), and performed as the substrate to enhance the photocurrents of PPIX (as photosensitizer) whose photoelectron transfer pathway and enhanced PEC mechanism were studied in detail. Under such foundation, a label-free PEC aptasensor was developed by deposition of DNA aptamer onto the PEC platform and then ultrasensitive assay of BNP-32 based on a "signal off" model. The biosensor showed a wide linear range (1 pg mL -1 - 0.1 μg mL -1 ) with a limit of detection (LOD) as low as 0.14 pg mL -1 . This doping technique of ZnO nanomaterials provides some valuable guidelines for synthesis of advanced PEC probes in bioanalysis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier B.V. All rights reserved.)

The interaction of a water-soluble cationic porphyrin, meso-tetrakis (4-N,N,N-trimethylanilinium) porphyrin (TMAP), with two proteins, bovine serum albumin (BSA) and human serum albumin (HSA), was studied by UV-vis absorption spectroscopy, fluorescence spectroscopy, fluorescence anisotropy and synchronous fluorescence spectroscopy at neutral aqueous solutions. Free base TMAP bound to proteins as monomers and no aggregation was observed. The binding of TMAP quenched the fluorescence of the protein. On the contrary, the fluorescence of TMAP was enhanced and the fluorescence anisotropy increased due to the binding. The direct static binding mechanism could account for the quenching by TMAP and the binding constants were calculated. TMAP showed a higher quenching efficiency and binding constant of HSA than BSA. The binding of TMAP had no obvious effect on the molecular conformation of the protein. There was only one binding site for TMAP and it was located on the surface of the protein molecule. Electrostatic force played an important role in the binding due to the opposite charges on porphyrin and the proteins.

Porphyrin and metalloporphyrin distribute widely in nature and they play an important role in the life. Synthesis of porphyrin compounds with special function has been the focus of attention. In the present paper, porphyrin and metalloporphyrin compound were synthesized by the following method: by one-step synthesis, tetra-(dimethylaminophenyl) porphyrin (T(DMAP) P) was synthesized with propionic acid, acetic acid and nitrobenzene as solvent and 4-dimethylaminobenzaldehyde and pyrrole as raw material. The yield was 24.24%. The complexes of T(DMAP)P with Zn2+, Mn2+ and Tb3+ were synthesized by solvent of chloroform-N, N dimethylformamide (1 : 1). The effects of solvent, temperature and reaction time on the reaction were discussed. Optimum proportion between porphyrin and metallic salts was studied also and the molar ratios of T(DMAP)P to Zn (CH3COO)2 x 2H2O, T(DMAP)P to MnCl2 x 4H2O, and T(DMAP)P to TbCl3 were 1 : 1.2, 1 : 1.4, 1 : 1.5, respectively. The synthesis of metalloporphyrins under mild conditions is simper with high yield (94.2%, 91.7% and 90.5% for T(DMAP) P combined with Zn2+ , Mn2+ and Tb3+ respectively) and the unstability of metalloporphyrin could be avoided. The constitution and structures of these compounds were studied by elemental analyses, infrared spectrum (IR), and ultraviolet-visible spectrum (UV-Vis). The conductivity of porphyrin compound with different concentration and temperature was studied. It was found that the molar conductivity of T(DMAP)P-TbCl(74.6 s x cm(-2) mol(-1)) was greater than that of T(DMAP)P-Zn (8. 8 s x cm(-2) x mol(-1)) and T(DMAP)P-Mn (25.8 s X cm(-2) mol(-1)). So T(DMAP) P-TbCl could be regarded as the 1 : 1 electrolyte compound while T(DMAP)P-Zn and T(DMAP)P-Mn were non-electrolyte compounds. The influences of different metal ions on the reaction were investigated. The discussion was concentrated on the molecular spectra of porphyrin and metalloporphyrin. Compared with tetraphenyl porphyrin, the absorption of T(DMAP) P and its metal complexes had red-shifts due to the substituent groups and metal ions. When the porphyrin rings were occupied by metal ions, the number of Q band decreased and the absorption peak intensity decreased. Among these metalloporphyrin compounds, the maximum absorption of T(DMAP)P-TbCl had the biggest red-shifts and could be used as ideal photosensitizer.

Abstract: High rate Li3V2(PO4)3/C composite with excellent electrochemical performance has been successfully synthesized via a sample carbon thermal method using meso-tetraphenyl porphyrin (TPP) as carbon source. The as prepared Li3V2(PO4)3/C composite delivers a reversible capacity of 103.71mAhg−1 at 20C charge/discharge rate. The Li+ diffusion coefficient ranges from 10−9 to 10−10 cm2 s−1 based on different scanning rates. The excellent high rate performance may attribute to the small particle size of the LVP/C and the carbon derived from thermal decomposition of TPP. In addition, its application in the full-cell, Li3V2(PO4)3‖Li4Ti5O12, is also presented and discussed. [Copyright &y& Elsevier]

In this study, a sensor for the sensitive determination of ascorbic acid (AA) has been fabricated based on meso-tetra-(3,5-dibromo-4-hydroxydroxyphenyl) porphyrin copper (II) (T(DBHP)P-Cu) modified Au electrode through l-cysteine ( l-cys). Firstly, l-cys modified Au electrode was prepared through self-assembled technology. Then T(DBHP)P-Cu was adsorbed on l-cys/Au through covalent binding. The fabrication process and electrochemical behavior of T(DBHP)P-Cu/ l-cys/Au were studied by cyclic voltammetry and differential pulse voltammetry. The results showed that AA exhibited good electrochemical activity at T(DBHP)P-Cu/ l-cys/Au. The oxidation peak current increased linearly with AA concentration in the range of 1.00 × 10-1.02 × 10 mol L with a detection limit of 5.41 × 10 mol L. Additionally, the modified electrode could be applied to the detect AA in practical samples. [ABSTRACT FROM AUTHOR]

The aggregation behavior of cationic meso-tetra-(4-trimethylaminophenyl)porphyrin (TAPP) was investigated in two reverse micelles (RM) of ionic surfactants, cetyltrimethylammonium bromide (CTAB) and bis(2-ethylhexyl)sulfosuccinate (AOT) using absorption spectroscopy, fluorescence spectroscopy, and resonance light scattering spectroscopy. TAPP showed different types of aggregation upon varying the ratio of water concentration to CTAB concentration, ω0. The charge on the surfactant used to form reverse micelles determines the aggregation of porphyrin. The addition of hydrochloric acid can transform the H-aggregates of TAPP into monomers, while the addition of sodium hydroxide led to J-aggregation. Ionic strength had no significant influence on the aggregation of TAPP. [ABSTRACT FROM AUTHOR]