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1.
J Photochem Photobiol B ; 201: 111640, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31734545

RESUMO

Fluorescence image guided surgical resection (FIGR) of high grade gliomas (HGGs) takes advantage of the accumulation of the tracer protoporphyrin IX (PpIX) in glioma cells following administration of 5-aminolevulinic acid (5-ALA). Occasionally, PpIX fluorescence intensity may be insufficient, thus compromising the efficacy and precision of the surgical intervention. The cause for the signal variation is unclear and strategies to improve the intensity of PpIX fluorescence are considered necessary. We have previously shown that differential expression of the epidermal growth factor receptor in glioblastoma cells affects PpIX fluorescence. Herein, we investigated other factors impairing PpIX accumulation and pharmacological treatments able to enhance PpIX fluorescence in glioblastoma cells displaying lower signal. In the present study we demonstrate that presence of serum in cell culture medium and differences in cellular confluence can negatively influence PpIX accumulation in U87 cell lines. We hypothesized that PpIX fluorescence intensity results from the interplay between the metabolic clearance of PpIX mediated by ferrochelatase and heme oxygenase-1 and the cellular efflux of PpIX through the ATP-binding cassette subfamily G member 2 (ABCG2). Based on the availability of compounds targeting these proteins and inhibiting them, in this study we used modulators such as genistein, an isoflavone able to inhibit ABCG2; deferoxamine, which chelate iron ions impairing FECH activity and tin protoporphyrin IX (SnPP), the specific HO-1 inhibitor. Finally, we showed the efficacy of a precisely tuned pharmacological treatment in increasing PpIX accumulation and consequently fluorescence in glioblastoma cells. This strategy may translate in more sensitive tracing of tumor cells in-vivo and improved FIGR of HGGs and possibly low grade gliomas (LGGs).


Assuntos
Corantes Fluorescentes/química , Microscopia Confocal , Protoporfirinas/química , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/antagonistas & inibidores , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP/metabolismo , Ácido Aminolevulínico/química , Ácido Aminolevulínico/metabolismo , Ácido Aminolevulínico/farmacologia , Neoplasias Encefálicas/patologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Receptores ErbB/metabolismo , Corantes Fluorescentes/metabolismo , Genisteína/metabolismo , Genisteína/farmacologia , Glioblastoma/patologia , Heme Oxigenase-1/antagonistas & inibidores , Heme Oxigenase-1/metabolismo , Humanos , Metaloporfirinas/química , Metaloporfirinas/metabolismo , Metaloporfirinas/farmacologia , Proteínas de Neoplasias/antagonistas & inibidores , Proteínas de Neoplasias/metabolismo , Protoporfirinas/metabolismo , Protoporfirinas/farmacologia
2.
Chem Commun (Camb) ; 55(65): 9590-9605, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31334709

RESUMO

The study of artificial receptor molecules with the intention to mimic enzyme-substrate binding processes and catalysis in nature has always been a traditional area of research in supramolecular chemistry. Along this line, our group has developed a family of porphyrin cage compounds based on glycoluril and employed these in host-guest binding studies, as components of allosterically controlled self-assembled processes, in which structural changes in the cage upon complexation of a guest or a ligand change binding equilibria, and as enzyme mimics in supramolecular catalysis. In a recently started research program aimed at developing a new molecular approach to long-term data storage, porphyrin cage compounds are studied as molecular machines to encode information into synthetic polymer chains. In this Feature Article we will give an overview of the above aspects of our porphyrin cage compounds and place them in the context of related systems reported in the literature.


Assuntos
Alquinos/química , Materiais Biomiméticos/química , Imidazóis/química , Porfirinas/química , Receptores Artificiais/química , Materiais Biomiméticos/síntese química , Catálise , Imidazóis/síntese química , Ligantes , Metaloporfirinas/síntese química , Metaloporfirinas/química , Nanotecnologia/métodos , Porfirinas/síntese química , Receptores Artificiais/síntese química , Estereoisomerismo , Termodinâmica
3.
ACS Appl Mater Interfaces ; 11(31): 27574-27587, 2019 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-31310503

RESUMO

A novel biscarbazol triphenylamine end-capped dendrimeric zinc(II) porphyrin (DP 5) was synthesized by click chemistry. This compound is a cruciform dendrimer that bears a nucleus of zinc(II) tetrapyrrolic macrocycle substituted at the meso positions by four identical substituents. These are formed by a tetrafluorophenyl group that possesses a triazole unit in the para position. This nitrogenous heterocyclic is connected to a 4,4'-di(N-carbazolyl)triphenylamine group by means of a phenylenevinylene bridge, which allows the conjugation between the nucleus and this external electropolymerizable carbazoyl group. In this structure, dendrimeric arms act as light-harvesting antennas, increasing the absorption of blue light, and as electroactive moieties. The electrochemical oxidation of the carbazole groups contained in the terminal arms of the DP 5 was used to obtain novel, stable, and reproducible fully π-conjugated photoactive polymeric films (FDP 5). First, the spectroscopic characteristics and photodynamic properties of DP 5 were compared with its constitutional components derived of porphyrin P 6 and carbazole D 7 moieties in solution. The fluorescence emissions of the dendrimeric units in DP 5 were more strongly quenched by the tetrapyrrolic macrocycle, indicating photoinduced energy transfer. In addition, FDP 5 film showed the Soret and Q absorption bands and red fluorescence emission of the corresponding zinc(II) porphyrin. Also, FDP 5 film was highly stable to photobleaching, and it was able to produce singlet molecular oxygen in both N,N-dimethylformamide (DMF) and water. Therefore, the porphyrin units embedded in the polymeric matrix of FDP 5 film mainly retain the photochemical properties. Photodynamic inactivation mediated by FDP 5 film was investigated in Staphylococcus aureus and Escherichia coli. When a cell suspension was deposited on the surface, complete eradication of S. aureus and a 99% reduction in E. coli survival were found after 15 and 30 min of irradiation, respectively. Also, FDP 5 film was highly effective to eliminate individual bacteria attached to the surface. In addition, photodynamic inactivation (PDI) sensitized by FDP 5 film produced >99.99% bacterial killing in biofilms formed on the surface after 60 min irradiation. The results indicate that FDP 5 film represents an interesting and versatile photodynamic active material to eradicate bacteria as planktonic cells, individual attached microbes, or biofilms.


Assuntos
Anti-Infecciosos/química , Carbazóis/química , Dendrímeros/química , Escherichia coli/crescimento & desenvolvimento , Membranas Artificiais , Metaloporfirinas/química , Staphylococcus aureus Resistente à Meticilina/crescimento & desenvolvimento
4.
Top Curr Chem (Cham) ; 377(3): 18, 2019 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-31161309

RESUMO

Manganese(III) porphyrin complexes with various metal-containing/non-metal bridges reported during the past two decades, including their structural characteristics and magnetic properties, are summarized. As the porphyrin ligands usually adopt a planar chelate form, it is possible that the porphyrin-based complexes, being a coordination-acceptor building block, have two coordination labile sites in trans positions. In particular, the coordination labile sites in an octahedral field face the direction of the Jahn-Teller elongated axis occupying the dz2 orbital. As a result of this characteristic orbital arrangement, the activity and magnetic-electronic properties of the manganese complexes can be tuned by modulating the porphyrin ligand, which is equatorially located around the manganese ion and coupled with the dx2-y2 orbital. The high-spin Mn(III) porphyrin complexes (S = 2) display strong magnetic uniaxial anisotropy with the Jahn-Teller axis as the magnetic easy axis. So far, various manganese(III) porphyrin magnetism systems, including multinuclear clusters, one-dimensional chains, and two- or three-dimensional networks, have been designed and structurally and magnetically characterized. This review shows that the manganese(III) porphyrin complexes have potential as versatile sources for the design of unique magnetic materials as well as other molecular functional materials with various structures.


Assuntos
Imãs/química , Metaloporfirinas/química , Complexos de Coordenação/química , Cristalografia por Raios X , Cianetos/química , Dimerização , Magnetismo/métodos , Modelos Moleculares
5.
Talanta ; 200: 472-479, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31036211

RESUMO

A new kind of nanoscale MOFs probe for nitric oxide (NO) sensing has been successfully constructed by a one-pot strategy, in which the chemically stable UiO-66 crystal structure was achieved using platinum meso-tetra(4-carboxyphenyl)porphyrin (Pt-TCPP), 1,1,2,2-Tetra(4-carboxylphenyl)ethylene (H4TCPE) and 1,4-dicarboxybenzene (BDC) as co-linkers (Pt-TCPP/H4TCPE@UiO-66). Pt-TCPP was verified to serve as a signal reporter in NO sensing fields for the first time while H4TCPE worked as a luminescence reference to build a ratiometric sensor. The integration of luminescent dyes in nanoscale MOFs effectively avoided their aggregation-caused quenching effect and poor aqueous dispersibility to rationalize NO detection in the aqueous phase. The obtained Pt-TCPP/H4TCPE@UiO-66 nanoparticles (NPs) exhibited an excellent sensing property toward NO with an ultrahigh linear correlation of the Stern-Volmer equation and a rapid response time as short as 2 min. Moreover, the elaborated sensor could work under a wide pH window (7.4, 5.6 and 0) and the limit of detection (LOD) reached as low as 0.1420 µg mL-1. The specificity of the obtained Pt-TCPP/H4TCPE@UiO-66 NPs toward NO sensing was scarcely affected by other possibly coexistent species in biological system. The in vitro monitoring for NO in living cells was also testified with these Pt-TCPP/H4TCPE@UiO-66 NPs.


Assuntos
Sobrevivência Celular , Substâncias Luminescentes/química , Estruturas Metalorgânicas/química , Metaloporfirinas/química , Óxido Nítrico/análise , Platina/química , Zircônio/química , Citometria de Fluxo , Células HeLa , Humanos , Medições Luminescentes , Imagem Óptica , Tamanho da Partícula , Propriedades de Superfície
6.
Int J Biol Macromol ; 134: 445-457, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31078597

RESUMO

The evidence that Human Serum Albumin (HSA) binds metal ions and organometallic compounds has generated interest in its physiological role as a metalloprotein and as a vehicle for synthetic biology applications (e.g., synthetic blood and solar energy conversion). HSA has been shown to bind metallo-porphyrins, however, the structural details of such interactions are available only for the HSA:heme complex. A typical challenge for studying the interaction of proteins with metalloporphyrins is the poor solubility of the ligands that affect the characterization the complexes. The manuscript shows that a combination of dialysis and centrifugation yields aqueous solutions that contain >90% HSA:porphyrin complexes and virtually eliminate aggregated ligands. The removal of aggregates increases the quality of the optical spectroscopy data which, in turn, yield more accurate binding constants (~0.1 and 2.1 × 106 M-1) and reveal FRET between Trp214 and the porphyrins. The Trp-porphyrin distance was estimated to be within the 28-34 Šrange and was used to guide the search of binding sites through a novel feedback approach with docking simulations. Results suggest while some protoporphyrins (metal-free, Fe(III)PPIX and Mg(II)PPIX) bind HSA at the heme site, others (Zn(II)PPIX, Mn(III)PPIX and Sn(IV)PPIX) are more likely to bind the Cys34.


Assuntos
Metaloporfirinas/química , Modelos Moleculares , Protoporfirinas/química , Albumina Sérica Humana/química , Albumina Sérica Humana/metabolismo , Sítios de Ligação , Complexos de Coordenação/química , Complexos de Coordenação/isolamento & purificação , Humanos , Ligantes , Metaloporfirinas/metabolismo , Conformação Molecular , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Ligação Proteica , Protoporfirinas/metabolismo , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral , Relação Estrutura-Atividade
7.
Nanoscale ; 11(21): 10178-10182, 2019 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-31111845

RESUMO

Manganese(iii)-chelated porphyrin microbubbles (MnP-MBs) were fabricated by self-assembly from a Mn-chelated porphyrin lipid followed by encapsulating perfluoropropane-an inert gas. The obtained MnP-MBs exhibited enhanced ultrasound imaging ability after intravenous injection. Under the guidance of ultrasound imaging, MnP-MBs could be converted into nanoparticles in situ with local tumor ultrasound disruption, achieving rapid tumor MRI contrast enhancement within 30 min at a very low Mn injection dose of 0.09 mg (1.65 µmol) per kg.


Assuntos
Meios de Contraste , Hematoporfirinas , Imagem por Ressonância Magnética , Metaloporfirinas , Microbolhas , Neoplasias Experimentais/diagnóstico por imagem , Ondas Ultrassônicas , Animais , Linhagem Celular Tumoral , Quelantes/química , Quelantes/farmacologia , Meios de Contraste/química , Meios de Contraste/farmacologia , Hematoporfirinas/química , Hematoporfirinas/farmacologia , Humanos , Metaloporfirinas/química , Metaloporfirinas/farmacologia , Camundongos , Camundongos Nus , Neoplasias Experimentais/metabolismo , Neoplasias Experimentais/patologia , Ultrassonografia
8.
Nanoscale ; 11(21): 10429-10438, 2019 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-31112176

RESUMO

Fluorescent dyes, as a key factor in fluorescence imaging, usually exhibit a low signal-to-noise ratio (SNR) due to the limited loading capacities of delivery systems (usually less than 10.0 wt%) and their uncontrolled release. Herein, we developed a type of pH-responsive nanoplatform (MnO2/ZnCOF@Au&BSA) based on a zinc porphyrin covalent organic framework (COF), in which the zinc porphyrin (ZnPor) loading rate is 22.5 wt%. At pH = 7.4, the interlinked ZnPor in the assembly state did not show a fluorescence signal ("off" state). Together with the pH-triggered disintegration of ZnCOF in tumor cells (pH = 5.5), the scattered ZnPor displayed an obvious fluorescence signal recovery ("on" state). Simultaneously, the shed BSA-coated gold nanoparticles ingeniously caused the fluorescence signal to be further amplified through the metal-enhanced fluorescence effect, which was about 3.0-fold higher in vivo than in the free ZnPor group. Combined with the excellent photothermal therapy effect by the nanoplatform itself with the tumor inhibition rate of 79.5%, this nanosystem effectively solves the problem of low loading capacities and imaging SNR by traditional delivery systems, and successfully develops the potential of COFs for fluorescence imaging, achieving the purpose of integration of diagnosis and treatment.


Assuntos
Sistemas de Liberação de Medicamentos , Ouro , Hipertermia Induzida , Compostos de Manganês , Metaloporfirinas , Nanoestruturas/química , Neoplasias Experimentais/terapia , Óxidos , Fotoquimioterapia , Animais , Feminino , Ouro/química , Ouro/farmacologia , Células Hep G2 , Humanos , Compostos de Manganês/química , Compostos de Manganês/farmacologia , Metaloporfirinas/química , Metaloporfirinas/farmacologia , Camundongos , Óxidos/química , Óxidos/farmacologia
9.
Biomed Res Int ; 2019: 7689183, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31011578

RESUMO

The self-assembly approach has been widely adopted in the effort to design and prepare functional materials. Herein, we report the synthesis and optical properties of metalloporphyrin nanoparticles. Nanoscaled particles of 5,10,15,20-tetraphenylporphyrin manganese (MnTPP) and 5,10,15,20-tetraphenylporphyrin indium (InTPP) were produced in the water/dimethylsulfoxide (DMSO) mixed solution by self-assembly approach. The absorbance intensity at the characteristic peak of the monomeric and nanoscaled metalloporphyrins decreased when they interact with dimethylmethylphosphonate (DMMP). Detection limits of MnTPP and InTPP nanoparticles to DMMP were 10-9 and 10-10 L/L, respectively, and detection limits of monomeric MnTPP and InTPP to DMMP were 10-6 and 10-7 L/L, respectively. Density functional theory (DFT) calculations on MnTPP and InTPP with DMMP as axial ligands had been performed in the B3LYP/6-31g (d) approximation. Their optimized geometries and binding energies were found to depend very strongly on the central metal ion, and InTPP was more sensitive for DMMP detection in contract to MnTPP. All the experimental and theoretical results demonstrated that nanoscaled metalloporphyrin have potential prospects in determination for public safety.


Assuntos
Metaloporfirinas/química , Nanopartículas/química , Compostos Organofosforados/química , Ligantes , Limite de Detecção , Metais/química
10.
Anal Bioanal Chem ; 411(13): 2905-2914, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31011780

RESUMO

Acetylcholinesterase (AChE) biosensor technology is widely applied in the detection of organophosphate pesticides in agricultural production via the inhibition of AChE activity by organophosphates. However, the AChE electrode has some drawbacks, such as low stability and high overpotential. Combining the advantages of multiwalled carbon nanotubes (MWCNTs) and ionic liquids, we constructed a novel bienzyme electrode [Cl/iron porphyrin (FePP)-modified MWCNTs/AChE/glassy carbon electrode], which included AChE and mimetic oxidase FePP. In this electrode, FePP is covalently bound to the AChE carrier via ionic liquid for increased electrode sensitivity and stability. Under optimal conditions, this novel biosensor has a monocrotophos detection limit of 3.2 × 10-11 mol/L and good recovery of 89-104%. After 5 weeks of storage at 4 °C, the oxidation current was 97.8% of its original value. The biosensor has high stability and sensitivity for monocrotophos detection and is a promising device for monitoring food safety. Graphical abstract The complete synthesis process of Cl/FePP-MWCNTs/AChE/GCE.


Assuntos
Acetilcolinesterase/química , Técnicas Biossensoriais/métodos , Enzimas Imobilizadas/química , Metaloporfirinas/química , Monocrotofós/análise , Nanotubos de Carbono/química , Praguicidas/análise , Materiais Biomiméticos/química , Brassica/química , Líquidos Iônicos/química , Compostos de Ferro/química , Alface/química , Limite de Detecção , Nanotubos de Carbono/ultraestrutura , Cebolas/química
11.
Molecules ; 24(6)2019 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-30901824

RESUMO

Zinc porphyrin-functionalized fullerene [C60] derivatives have been synthesized and used to prepare titania-based composites. The electrochemical properties and HOMO and LUMO levels of the photosensitizers were determined by electrochemical measurements. Raman and IR techniques were used to study chemical groups present on the titania surface. Absorption properties of the composites were measured in the solid state by diffuse reflectance UV-Vis spectra (DRS). The zeta potential and aggregate sizes were determined using dynamic light scattering (DLS) and electrophoretic light scattering (ELS) techniques. Surface areas were estimated based on Brunauer⁻Emmett⁻Teller (BET) isotherms. The photocatalytic activity of the photocatalysts was tested using two model pollutants, phenol and methylene blue. The composite with the highest photocatalytic potential (1/TiO2) was used for river and wastewater remediation. The photodegradation intermediates were identified by LC-UV/Vis-MS/MS techniques.


Assuntos
Fulerenos , Luz , Metaloporfirinas , Titânio , Catálise , Recuperação e Remediação Ambiental , Água Doce , Fulerenos/química , Metaloporfirinas/química , Processos Fotoquímicos , Reprodutibilidade dos Testes , Rios , Espectroscopia de Infravermelho com Transformada de Fourier , Titânio/química , Águas Residuárias , Poluentes Químicos da Água/química
12.
Colloids Surf B Biointerfaces ; 178: 137-145, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30852265

RESUMO

Nanozymes, nanomaterial-based artificial enzymes, have attracted researchers' enormous interest due to their unique properties compared with natural enzymes. To mimic the catalytic function of natural enzymes, designing high-efficient, novel nanozymes is crucial yet challenging task. In this article, we described the synthesis and functions of a metalloporphyrin-based porous organic polymer, namely FePPOPs-SO3H. FePPOPs-SO3H was synthesized effortlessly via an extensive aromatic electrophilic substitution and the following sulfonation reactions. This strategy was cost-efficient without the participation of precious metal catalysts. The resultant FePPOPs-SO3H is intriguing since the framework itself is constructed by covalently linked porphyrin units, which could serve as a built-in catalyst and strengthen the stability of polymer. With sulfonic acid side groups, FePPOPs-SO3H is well water-dispersive. Owing to these unique characteristics, FePPOPs-SO3H exhibited excellent peroxidase-like activity toward a classical peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) to produce a blue product only within 20 s. The peroxidase-mimicking performance of FePPOPs-SO3H outperforms the ferric porphyrin monomer and normal Fe3O4 nanoparticles. Based on the excellent catalytic activity of FePPOPs-SO3H, two visual colorimetric sensors for ultrafast detecting H2O2 and glucose, respectively, were constructed with a wide linear range of 50-1800 µM (for H2O2) and 200-1500 µM (for glucose), as well as a relative lower limit of detection (LOD) [26.70 µM (for H2O2) and 16.38 µM (for glucose)]. Our strategy highlights opportunities for the design of new metalloporphyrin-based porous organic polymers with built-in catalytic skeletons and inherently excellent peroxidase-mimicking performance.


Assuntos
Glucose/química , Peróxido de Hidrogênio/química , Metaloporfirinas/química , Polímeros/química , Colorimetria , Interações Hidrofóbicas e Hidrofílicas , Peroxidase/metabolismo
13.
Macromol Biosci ; 19(5): e1800407, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30721575

RESUMO

The development of plant viral nanoparticles (VNP) loaded with different molecular versions of a photodynamic drug is described. Specifically, tobacco mosaic virus (TMV) and tobacco mild green mosaic virus (TMGMV) are developed as drug carriers that encapsulate the monocationic, dicationic, tricationic, and tetracationic versions of a porphyrin-based photosensitizer drug (Zn-Por). While TMV has been extensively explored for various nanotechnology applications, this is the first study investigating TMGMV for medical applications. Light-activated cancer cell killing of Zn-Por-loaded VNPs is studied in vitro using melanoma and cervical cancer models. Native and nucleolin-targeted VNP drug carriers are developed and their efficacy assessed. A fivefold increase in cancer cell killing is observed using nucleolin-targeted TMV loaded with tricationic Zn-Por and displaying the nucleolin-specific F3 peptide.


Assuntos
Melanoma Experimental/tratamento farmacológico , Metaloporfirinas , Nanopartículas , Fotoquimioterapia , Vírus do Mosaico do Tabaco/química , Animais , Linhagem Celular Tumoral , Portadores de Fármacos/química , Portadores de Fármacos/farmacologia , Melanoma Experimental/metabolismo , Melanoma Experimental/patologia , Metaloporfirinas/química , Metaloporfirinas/farmacologia , Camundongos , Nanopartículas/química , Nanopartículas/uso terapêutico
14.
Inorg Chem ; 58(5): 2954-2964, 2019 Mar 04.
Artigo em Inglês | MEDLINE | ID: mdl-30735039

RESUMO

Emulating enzymatic reactivity using small molecules has been a long-time challenging pursuit of the scientific community. Peroxidases, ubiquitous heme enzymes that are involved in hormone synthesis and the immune system, have been a prime target of such efforts due to their tremendous potential in the chemical industry as well as in wastewater treatment. Here it is demonstrated that inclusion of a second sphere guanidine moiety in an iron porphyrin not only makes this small molecule a veritable peroxidase catalyst but also offers an auxiliary binding site for organic substrates, facilitating their rapid oxidation with a green oxidant like H2O2. This small molecule analogue exhibits a "ping-pong" mechanism and Michaelis-Menten type kinetics, which is generally typical of metallo-enzymes and follows a mechanism of the natural enzyme in its entirety, including the formation of compound I as the primary oxidant.


Assuntos
Ferro/metabolismo , Metaloporfirinas/metabolismo , Peroxidases/metabolismo , Sítios de Ligação , Biocatálise , Cristalografia por Raios X , Guanidina/química , Guanidina/metabolismo , Peróxido de Hidrogênio/química , Peróxido de Hidrogênio/metabolismo , Ferro/química , Cinética , Metaloporfirinas/síntese química , Metaloporfirinas/química , Modelos Moleculares , Estrutura Molecular , Oxirredução , Peroxidases/química
15.
Int J Mol Sci ; 20(3)2019 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-30736413

RESUMO

The development of UV⁻vis spectrophotometric methods based on metalloporphyrins for fast, highly sensitive and selective anion detection, which avoids several of the practical challenges associated with other detection methods, is of tremendous importance in analytical chemistry. In this study, we focused on achieving a selective optical sensor for triiodide ion detection in traces based on a novel hybrid material comprised of Pt(II) 5,10,15,20-tetra(4-methoxy-phenyl)-porphyrin (PtTMeOPP) and gold nanoparticles (AuNPs). This sensor has high relevance in medical physiological tests. The structure of PtTMeOPP was investigated by single crystal X-ray diffraction in order to understand the metal surroundings and the molecule conformation and to assess if it qualifies as a potential sensitive material. It was proven that the Pt-porphyrin generated 1D H-bond supramolecular chains due to the weak C-H···O intermolecular hydrogen bonding. The presence of ordered voids in the crystal encouraged us to use PtTMeOPP as the sensing material for triiodide ion and to enhance its potential in a novel AuNPs/PtTMeOPP hybrid by the synergistic effects provided by the plasmonic gold nanoparticles. The spectrophotometric sensor is characterized by a detection limit of 1.5 × 10-9 M triiodide ion concentration and a remarkable confidence coefficient of 99.98%.


Assuntos
Ânions/análise , Ouro , Iodetos/análise , Nanopartículas Metálicas , Metaloporfirinas/química , Modelos Moleculares , Compostos Organoplatínicos/química , Ouro/química , Nanopartículas Metálicas/química , Nanopartículas Metálicas/ultraestrutura , Microscopia de Força Atômica , Conformação Molecular , Termogravimetria
16.
Chem Commun (Camb) ; 55(21): 3081-3084, 2019 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-30785463

RESUMO

Hydrogen as a renewable fuel is viable when produced sustainably via proton reduction catalysis (PRC). Many homogeneous electrocatalysts perform PRC with high rates, but they all require a large overpotential to drive the reaction. Natural hydrogenase enzymes achieve reversible PRC with potentials close to the thermodynamic equilibrium through confinement of the active site in a well-defined protein pocket. Inspired by nature, we report a strategy that relies on the selective encapsulation of a synthetic hydrogenase mimic in a novel supramolecular cage. Catalyst confinement decreases the PRC overpotential by 150 mV, and is proposed to originate from the cationic cage stabilizing anionic reaction intermediates within the catalytic cycle.


Assuntos
Materiais Biomiméticos/química , Hidrogenase/química , Compostos de Ferro/química , Metaloporfirinas/química , Prótons , Catálise , Domínio Catalítico , Modelos Moleculares , Oxirredução , Termodinâmica
17.
Proc Natl Acad Sci U S A ; 116(8): 2854-2859, 2019 02 19.
Artigo em Inglês | MEDLINE | ID: mdl-30718404

RESUMO

Hemoglobin and myoglobin are oxygen-binding proteins with S = 0 heme {FeO2}8 active sites. The electronic structure of these sites has been the subject of much debate. This study utilizes Fe K-edge X-ray absorption spectroscopy (XAS) and 1s2p resonant inelastic X-ray scattering (RIXS) to study oxyhemoglobin and a related heme {FeO2}8 model compound, [(pfp)Fe(1-MeIm)(O2)] (pfp = meso-tetra(α,α,α,α-o-pivalamido-phenyl)porphyrin, or TpivPP, 1-MeIm = 1-methylimidazole) (pfpO2), which was previously analyzed using L-edge XAS. The K-edge XAS and RIXS data of pfpO2 and oxyhemoglobin are compared with the data for low-spin FeII and FeIII [Fe(tpp)(Im)2]0/+ (tpp = tetra-phenyl porphyrin) compounds, which serve as heme references. The X-ray data show that pfpO2 is similar to FeII, while oxyhemoglobin is qualitatively similar to FeIII, but with significant quantitative differences. Density-functional theory (DFT) calculations show that the difference between pfpO2 and oxyhemoglobin is due to a distal histidine H bond to O2 and the less hydrophobic environment in the protein, which lead to more backbonding into the O2 A valence bond configuration interaction multiplet model is used to analyze the RIXS data and show that pfpO2 is dominantly FeII with 6-8% FeIII character, while oxyhemoglobin has a very mixed wave function that has 50-77% FeIII character and a partially polarized Fe-O2 π-bond.


Assuntos
Ferro/química , Oxigênio/química , Oxiemoglobinas/química , Porfirinas/química , Domínio Catalítico , Compostos Férricos/química , Heme/química , Metaloporfirinas/química , Modelos Moleculares , Mioglobina/química , Espalhamento de Radiação , Espectroscopia por Absorção de Raios X , Raios X
18.
J Appl Oral Sci ; 27: e20180051, 2019 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-30673027

RESUMO

The efficacy of whitening toothpastes is questionable and controversial. Clinicians, patients and researchers have expressed concern with whitening toothpastes due to the risk of wearing the dental structure and the potential for disappointment if the advertised cosmetic results are not achieved. OBJECTIVE: This study compared the whitening performance of toothpastes with different whitening technologies after initial and continued use. MATERIAL AND METHODS: Ninety bovine incisors were stained using a concentrated solution of black tea. They were randomly distributed into 6 groups, according to the toothpaste whitening technology: activated charcoal (B&W), blue covarine (WAD), hydrogen peroxide (LWA), microbeads (Oral B 3D White Perfection - 3DW) and optimized abrasives (XW4D). They were compared to a traditional toothpaste without a whitening agent (TA - control). Specimens underwent a brushing machine with controlled pressure, time and temperature. A calibrated examiner measured the color using a VITA-Classical scale before the first brushing cycle (T0), after the first brushing cycle (TI), and after a brushing cycle that simulates continuous use (TCU). Whitening performance was evaluated by the difference of shades (ΔSGU) between T0-TI and T0-TCU timepoints, using the Kruskal-Wallis and Dunn's non-parametric test. The Wilcoxon test was used to evaluate the cumulative effect (α=0.05). RESULTS: Statistically significant differences were observed between toothpastes in both TI and TCU (p<0.05). The time of use also had a significant effect (p<0.05). CONCLUSION: Only WAD and 3DW showed whitening performance after the first use (TI). The greatest whitening performance after continuous use was obtained by WAD, followed by LWA and 3DW. The use of conventional toothpaste (TA) promotes no tooth whitening. CLINICAL RELEVANCE: Microbead abrasives (3DW) and blue covarine (WAD) were the active technology tested that presented the best global tooth whitening performance.


Assuntos
Carvão Vegetal/química , Peróxido de Hidrogênio/química , Isoindóis/química , Metaloporfirinas/química , Microesferas , Clareadores Dentários/química , Clareamento Dental/métodos , Cremes Dentais/química , Animais , Bovinos , Distribuição Aleatória , Valores de Referência , Reprodutibilidade dos Testes , Propriedades de Superfície , Fatores de Tempo , Dente/efeitos dos fármacos , Escovação Dentária/métodos
19.
Inorg Chem ; 58(4): 2627-2636, 2019 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-30694043

RESUMO

A heme oxygen binding behavior was described through a unique geometric and electronic comparison of zinc porphyrin complexes. In this work, a charge transfer model for saddled metalloporphyrin complexes outlined the push effects of the ring nonplanarity and axial imidazole, and the pull effect of the axial dioxygen. The origin and role of the horizontal (ring nonplanarity) push effect and its relationship to the vertical (axial ligand) push/pull effect and its contribution to dioxygen binding were considered from the perspectives of crystal structures, theoretical calculations, and bathochromic shifts. Single-point energy and molecular orbital calculations starting from crystal structures were used to obtain the electronic structures of zinc porphyrin complexes. This study not only revealed that the electronic behavior of metalloporphyrins is driven by ring nonplanarity and axial ligation but also afforded new insight into the oxygen carrier mechanism in heme.


Assuntos
Heme/química , Metaloporfirinas/química , Transporte de Elétrons , Modelos Moleculares , Conformação Molecular
20.
Phys Chem Chem Phys ; 21(5): 2378-2381, 2019 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-30649113

RESUMO

One of the fundamental challenges in molecular-scale sensors is the junction to junction variability leading to variations in their electrical conductance by up to a few orders of magnitude. In contrast, thermal voltage measurements of single and many molecule junctions show that this variation in the Seebeck coefficient is smaller. Particularly, the sign of the Seebeck coefficient is often resilient against conformational changes. In this paper, we demonstrate that this robust molecular feature can be utilised in an entirely new direction of discriminating molecular sensing of gas and bio-molecules. We show that the positive sign of the Seebeck coefficient in the presence of cytosine nucleobases changes to a negative one when cancerous cytosine nucleobases were absorbed on the molecular wire formed by metalloporphyrins. Furthermore, the sign of the Seebeck coefficient changes when chlorine gas interacts with the Mn-porphyrin molecular wire. The change in the sign of Seebeck coefficient is due to the formation of spin driven bound states with energies close to the Fermi energy of electrodes. Seebeck sensing is a generic concept and opens new avenues for molecular sensing with huge potential applications in the years ahead.


Assuntos
Condutividade Elétrica , Técnicas Eletroquímicas/métodos , Metaloporfirinas/química , Cloro/análise , Cloro/química , Citosina/análogos & derivados , Citosina/análise , Teoria da Densidade Funcional , Eletrodos , Grafite/química , Calefação , Manganês/química , Níquel/química , Teoria Quântica
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